Mobile crane undercarriage

Abstract

To provide an undercarriage of a mobile crane capable of suppressing displacement generated on the undercarriage when a suspended cargo is suspended from a revolving super structure in front of or behind of the undercarriage, while suppressing the deterioration of workability of disassembling work of the undercarriage and suppressing an increase in dimensions of components configuring the undercarriage.SOLUTION: In each of a plurality of coupling members 11R, 12R, 11L and 12L, one of a car body connecting portion and a crawler connecting portion is a rotary connecting portion, and the other is an attaching / detaching connecting portion. Each of the plurality of coupling members 11R, 12R, 11L and 12L is configured to be disposed at an approach position where the attaching / detaching connecting portion is located near a rotated member as compared with a bulging position, by rotating at the attaching / detaching connecting portion while the attaching / detaching connecting portion is removed from a detached / attached member.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an undercarriage of a mobile crane. [Background technology]

[0002] Conventionally, mobile cranes are known. For example, the mobile crane of Patent Document 1 includes a lower traveling body capable of traveling on the ground and an upper rotating body mounted on the lower traveling body. The upper rotating body includes a working device including a boom and a hoisting rope. The lower traveling body includes a car body that supports the upper rotating body so that it can rotate around a rotation center axis, a right crawler frame extending in the front-rear direction on the right side of the car body, a left crawler frame extending in the front-rear direction on the left side of the car body, a front axle extending parallel to the left-right direction from the car body, and a rear axle extending parallel to the left-right direction from the car body behind the front axle. The right crawler frame supports a right part of the front axle and a right part of the rear axle, and the left crawler frame supports a left part of the front axle and a left part of the rear axle. In this way, the front axle and the rear axle extending parallel to the left-right direction from the car body connect the car body to the left and right crawler frames. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-70339 A [Patent Document 2] JP 2017-171090 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a lower traveling body having a structure in which front and rear axles extending in parallel in the left-right direction from the car body connect the car body to the left and right crawler frames, the rigidity in the front-rear direction is lower than the rigidity in the left-right direction. Therefore, in a lifting operation (crane operation) of a mobile crane, when a load is suspended from an upper rotating body via the hoisting rope of the working device in front of or behind the lower traveling body, the amount of downward displacement of the front or rear part of the car body tends to be larger than the amount of downward displacement of the right or left part of the car body when a load is suspended from the upper rotating body to the side of the lower traveling body.

[0005] Specifically, when a load is suspended from the upper rotating body in front of or behind the lower running body, the load that the car body receives from the upper rotating body causes deformations such as torsional deformation and bending deformation in the front and rear axles, and deformations also occur in the car body, so that the front or rear part of the car body is likely to be displaced downward. In addition, deformations are likely to occur in the left and right crawler frames in response to the deformations of the front and rear axles. As a result, the degree of deformation occurring in the lower running body varies with the change in the rotation position of the upper rotating body, which causes the position of the suspended load to fluctuate up and down, which may reduce the workability of the lifting operation. Therefore, it is desirable to reduce the deformation occurring in the lower running body when a load is suspended from the upper rotating body in front of or behind the lower running body by improving the rigidity in the front-rear direction of the lower running body.

[0006] Patent Document 2 discloses a technique of providing a pair of reinforcing members at the front and rear of the trunk of the car body in order to improve the rigidity of the front and rear parts of the car body. However, since various components such as a rotation motor for rotating the upper rotating body, gears, hydraulic piping, and electric wiring are arranged around the trunk of the car body where the pair of reinforcing members are provided, there are cases where it is not possible to secure a sufficient space for arranging the pair of reinforcing members. In this case, the effect of suppressing the deformation of the car body by the pair of reinforcing members is limited.

[0007] In addition, when taking measures to improve the fore-and-aft rigidity of the lower running body, it is necessary to suppress any reduction in workability in the disassembly work of disassembling the lower running body in order to transport the mobile crane, and in the assembly work of assembling the lower running body after transporting the mobile crane, and further, it is necessary to suppress any increase in the dimensions of the parts that make up the lower running body so that their dimensions fall within the range of transportation limit dimensions during transport.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a lower running body of a mobile crane that can minimize deformation that occurs in the lower running body when a load is suspended from an upper rotating body in front of or behind the lower running body, while suppressing a decrease in the workability of disassembling and assembling the lower running body and suppressing an increase in the dimensions of the parts that make up the lower running body. [Means for solving the problem]

[0009] What is provided is a lower traveling body of a mobile crane, comprising: a carbody supporting an upper rotating body of the mobile crane so as to be rotatable about a central axis of rotation, a right crawler frame extending in a front-rear direction on the right side of the carbody, a left crawler frame extending in the front-rear direction on the left side of the carbody, and a plurality of connecting members, the plurality of connecting members including a right front connecting member having a carbody connection part connected to the carbody and a crawler connection part connected to the right crawler frame, the crawler connection part connecting the carbody and the right crawler frame at a protruding position located diagonally to the right front of the carbody connection part, a right rear connecting member having a carbody connection part connected to the carbody and a crawler connection part connected to the right crawler frame, the right rear connecting member connecting the carbody and the right crawler frame at a protruding position located diagonally to the right rear of the carbody connection part of the right rear connecting member, and a right front connecting member having a carbody connection part connected to the carbody and a crawler connection part connected to the right crawler frame, the right rear connecting member connecting the carbody and the right crawler frame at a protruding position located diagonally to the right rear of the carbody connection part of the right rear connecting member, a left front connecting member having a car body connection part connected to the car body and a crawler connection part connected to the left crawler frame, wherein the crawler connection part of the left front connecting member connects the car body and the left crawler frame at a protruding position located diagonally left front of the car body connection part of the left front connecting member, and a left rear connecting member having a car body connection part connected to the car body and a crawler connection part connected to the left crawler frame, wherein the crawler connection part of the left rear connecting member connects the car body and the left crawler frame at a protruding position located diagonally left rear of the car body connection part of the left rear connecting member. In each of the multiple connecting members, one of the car body connection part and the crawler connection part is a rotating connection part, and the other is a detachable connection part. The rotating connection part is rotatably connected to a rotated member which is a member of the car body, the right crawler frame, or the left crawler frame to which the rotating connection part is connected. The detachable connection portion is detachably connected to a receiving member which is a member to which the detachable connection portion is connected among the car body, the right crawler frame, and the left crawler frame.Each of the multiple connecting members is configured so that, when the detachable connection portion is detached from the detachable member, it can be rotated at the pivotal connection portion so that the detachable connection portion can be positioned in an approaching position that is closer to the rotatable member than the extended position.

[0010] In this lower traveling body, a structure is adopted in which one of the car body connection part and the crawler connection part of each of the multiple connecting members is the above-mentioned pivot connection part and the other is the above-mentioned detachable connection part, and each connecting member is configured to be disposed in the above-mentioned extended position during crane operation and to be disposed in the above-mentioned close position during transportation of the mobile crane. This makes it possible to simultaneously suppress a decrease in the workability of disassembling and assembling the lower traveling body, suppress an increase in the dimensions of the parts that constitute the lower traveling body, and reduce deformation that occurs in the lower traveling body when a load is suspended from the upper rotating body in front of or behind the lower traveling body. Specifically, it is as follows.

[0011] The right front connecting member arranged in the extended position during crane operation can receive the front load, which is the load that the car body receives from the upper rotating body when a load is suspended from the upper rotating body forward of the lower running body, at the car body connection part of the right front connecting member, and transmit it to the right crawler frame via the crawler connection part located diagonally forward to the right of the car body connection part. Similarly, the left front connecting member can receive the front load at the car body connection part of the left front connecting member, and transmit it to the left crawler frame via the crawler connection part located diagonally forward to the left of the car body connection part. In other words, the right front connecting member and the left front connecting member can support the car body forward of the car body connection part, which is the part that receives the front load from the car body. This suppresses the occurrence of torsional deformation in the right front connecting member and the left front connecting member, effectively suppressing the downward displacement of the front part of the car body. When the occurrence of torsional deformation in the right front connecting member and the left front connecting member is suppressed, the deformation of the left and right crawler frames is also suppressed. Therefore, it is possible to reduce deformation of the lower traveling body when a load is suspended from the upper rotating body forward of the lower traveling body. The reason why it is possible to reduce deformation of the lower traveling body when a load is suspended from the upper rotating body rearward of the lower traveling body is the same as above.

[0012] Moreover, in the disassembly work of the lower traveling body, the worker does not need to remove one of the connection parts (detachable connection part) of the car body connection part and the crawler connection part of each of the multiple connecting members from the detachable member while removing the other connection part (rotating connection part) of the car body connection part and the crawler connection part from the detachable member. That is, the worker can displace each of the multiple connecting members from the protruding position to the approaching position by rotating each of the multiple connecting members at the rotating connection part after removing the detachable connection part of each of the multiple connecting members from the detachable member. This prevents a decrease in the workability of the disassembly work and also prevents an increase in the dimensions of the parts that constitute the lower traveling body. In addition, in the assembly work of the lower traveling body, the worker can connect the car body to the left and right crawler frames by rotating each of the multiple connecting members at the rotating connection part to displace each of the multiple connecting members from the approaching position to the protruding position, and then attaching one of the connection parts (detachable connection part) of the car body connection part and the crawler connection part of each of the multiple connecting members to the detachable member. Therefore, the efficiency of the assembly work is prevented from being reduced.

[0013] In the lower running body of the mobile crane, it is preferable that at least one of the multiple connecting members is configured so that it can be positioned in the extended position and used as a lifting member for lifting the car body during at least one of an assembly operation for assembling the lower running body and a disassembly operation for disassembling the lower running body.

[0014] In this embodiment, the at least one connecting member also functions as a lifting member (translifter). That is, the connecting member functions as a load transmitting member that transmits a load to the crawler frame during crane operation, while also functioning as a lifting member during at least one of the assembly and disassembly operations of the lower traveling body. The connecting member is disposed at the extended position both when functioning as a load transmitting member and when functioning as a lifting member. Therefore, the assembly operation, disassembly operation, and crane operation can each be performed with the connecting member disposed at the same position (the extended position). This allows a smooth transition from assembly operation to crane operation, and also allows a smooth transition from crane operation to disassembly, and also suppresses an increase in the number of parts caused by providing a lifting member separately from the connecting member.

[0015] Specifically, it is preferable that the at least one connecting member further includes a connecting member main body connecting the car body connection portion and the crawler connection portion, and a leg portion supported by the connecting member main body, and that the leg portion is configured to be displaceable between a remote position away from the ground and a contact position extending downward from the connecting member main body and in contact with the ground.

[0016] In this aspect, by displacing the leg between the separated position and the contact position, it is possible to transition from assembly work to crane work and from crane work to disassembly work.

[0017] It is preferable that the lower running body of the mobile crane further includes a plurality of extension position fixing members for fixing the plurality of connecting members to the extension positions, respectively.

[0018] In this embodiment, in the assembly work of assembling the lower running body, the detachable parts of the connecting members are attached to the corresponding detachable target members in a state in which the connecting members are fixed to the protruding positions by the protruding position fixing members, respectively, thereby improving the workability of the assembly work of the lower running body.

[0019] It is preferable that the undercarriage of the mobile crane further includes a plurality of approach position fixing members for fixing the plurality of connecting members to the approach positions, respectively.

[0020] In this aspect, it is possible to prevent each of the multiple connecting members from being displaced relative to the target attachment / detachment members during transportation of the mobile crane.

[0021] It is preferable that the lower running body of the mobile crane has at least one right intermediate connection part connected to the right crawler frame rear of the right front connecting member and forward of the right rear connecting member, and at least one left intermediate connection part connected to the left crawler frame rear of the left front connecting member and forward of the left rear connecting member.

[0022] In this embodiment, the right front connecting member and the right rear connecting member not only connect the car body to the right crawler frame, but also connect the right intermediate connection part of the car body to the right crawler frame between these connecting members. This suppresses deformation of the intermediate part between the part of the right crawler frame to which the right front connecting member is connected and the part of the right rear connecting member is connected. Similarly, the left front connecting member and the left rear connecting member not only connect the car body to the left crawler frame, but also connect the left intermediate connection part of the car body to the left crawler frame between these connecting members. This suppresses deformation of the intermediate part between the part of the left crawler frame to which the left front connecting member is connected and the part of the left rear connecting member is connected. In addition, in this embodiment, the load of the upper rotating body and the suspended load is not only transmitted to the left and right crawler frames via the multiple connecting members, but is also distributed to the right intermediate connection part and the left intermediate connection part and transmitted to the left and right crawler frames, so that the multiple connecting members can be constructed from relatively simple members.

[0023] the lower running body of the mobile crane further comprises a pair of right wheels rotatably supported on a front end and a rear end of the right crawler frame, a pair of left wheels rotatably supported on a front end and a rear end of the left crawler frame, a plurality of right rollers arranged at intervals in the front-rear direction between the pair of right wheels and rotatably supported on a lower part of the right crawler frame, the plurality of right rollers including a front-most right front end roller and a rear-most right rear end roller, and a plurality of left rollers arranged at intervals in the front-rear direction between the pair of left wheels and rotatably supported on a lower part of the left crawler frame, the plurality of left rollers including a front-most left front end roller and a rear-most left rear end roller, the right front connecting member has a right front load receiving surface facing the car body and a right front load transfer surface facing the right crawler frame, the left front connecting member has a left front load receiving surface facing the car body and a left front load transfer surface facing the left crawler frame, and each of the right front load receiving surface of the right front connecting member and the left front load receiving surface of the left front connecting member is a surface that can receive, from the car body, a front load that is a load that the car body receives from the upper rotating body when a load is suspended from the upper rotating body forward of the lower running body, and the right front load transfer surface is a surface that can transfer the front load to the right crawler frame, and the left front load transfer surface is a surface that can transfer the front load to the left crawler frame. It is preferable that the right front connecting member is configured so that a right front straight line, which is a straight line passing through any point included in the right front load receiving surface and any point included in the right front load transfer surface in a plan view, passes forward of the right front end roller or the right front end roller, and the left front connecting member is configured so that a left front straight line, which is a straight line passing through any point included in the left front load receiving surface and any point included in the left front load transfer surface in a plan view, passes forward of the left front end roller or the left front end roller.

[0024] The right and left front connecting members of the lower traveling body are configured so that the right and left front straight lines and the right and left front end rollers have the above-mentioned positional relationship, so that it is possible to effectively reduce the front-to-rear distance between the portion of the right crawler frame to which the front load is transmitted via the right front connecting member and the front end of the right crawler frame, and it is possible to effectively reduce the front-to-rear distance between the portion of the left crawler frame to which the front load is transmitted via the left front connecting member and the front end of the left crawler frame. This makes it possible to reduce deflection that occurs in the front portions of the left and right crawler frames when a load is suspended from the upper rotating body forward of the lower traveling body.

[0025] Here, when the car body receives a relatively large front load from the upper rotating body, the right front end roller and the left front end roller become approximate tipping fulcrums (front tipping fulcrums), so it is preferable that the right front straight line is a straight line passing through the right front end roller in a planar view, and the left front straight line is a straight line passing through the left front end roller in a planar view.

[0026] In this aspect, the right front connecting member and the left front connecting member can directly transmit the front load to the portions of the left and right crawler frames that correspond to the front tipping fulcrum, making it possible to more effectively reduce the deflection that occurs in the front portions of the left and right crawler frames due to the front load.

[0027] It is also preferable that the right front straight line is a straight line that further passes through the central axis of rotation in a plan view, and the left front straight line is a straight line that further passes through the central axis of rotation in a plan view.

[0028] In this embodiment, any point on the right front load receiving surface of the right front connecting member and any point on the right front load transfer surface of the right front connecting member can be positioned on a right front straight line passing through the turning center axis and the right front end roller in a plan view, and any point on the left front load receiving surface of the left front connecting member and any point on the left front load transfer surface of the left front connecting member can be positioned on a left front straight line passing through the turning center axis and the left front end roller in a plan view. This makes it possible to approximate the path along which the front load is transferred to the right crawler frame by the right front connecting member to the direction from the turning center axis toward the right front end roller, and to approximate the path along which the front load is transferred to the left crawler frame by the left front connecting member to the direction from the turning center axis toward the left front end roller, so that the front load is efficiently transferred to portions of the left and right crawler frames that correspond to the front tipping fulcrums.

[0029] In the lower running body of the mobile crane, it is preferable that the right front connecting member has a right front continuing portion that continues from the right front load receiving surface to the right front load transfer surface along the right front straight line in a planar view, and the left front connecting member has a left front continuing portion that continues from the left front load receiving surface to the left front load transfer surface along the left front straight line in a planar view.

[0030] In this aspect, the right front continuing portion continues without interruption from the right front load receiving surface to the right front load transfer surface along the right front straight line in a plan view, and the left front continuing portion continues without interruption from the left front load receiving surface to the left front load transfer surface along the left front straight line in a plan view.Therefore, the front load received by the right front load receiving surface and the left front load receiving surface is transmitted continuously and efficiently along the right front continuing portion and the left front continuing portion to the right front load transfer surface and the left front load transfer surface, and from these load transfer surfaces to the left and right crawler frames.

[0031] In the lower running body of the mobile crane, the right rear connecting member has a right rear load receiving surface facing the car body and a right rear load transfer surface facing the right crawler frame, and the left rear connecting member has a left rear load receiving surface facing the car body and a left rear load transfer surface facing the left crawler frame, and each of the right rear load receiving surface of the right rear connecting member and the left rear load receiving surface of the left rear connecting member is a surface that can receive, from the car body, a rear load that is a load that the car body receives from the upper rotating body when a load is suspended from the upper rotating body rearward of the lower running body, and the right rear load transfer surface is a surface that can receive the rear load from the car body. the right crawler frame, the left rear load transfer surface is a surface that can transfer the rear load to the left crawler frame, the right rear connecting member is configured so that a right rear straight line, which is a straight line passing through any point included in the right rear load receiving surface and any point included in the right rear load transfer surface in a planar view, passes rear of the right rear end roller or the right rear end roller, and the left rear connecting member is more preferably configured so that a left rear straight line, which is a straight line passing through any point included in the left rear load receiving surface and any point included in the left rear load transfer surface in a planar view, passes rear of the left rear end roller or the left rear end roller.

[0032] The right and left rear connecting members of the lower traveling body are configured so that the right and left rear straight lines and the right and left rear end rollers have the above-mentioned positional relationship, so that the front-to-rear distance between the portion of the right crawler frame to which the rear load is transmitted via the right rear connecting member and the rear end of the right crawler frame can be effectively reduced, and the front-to-rear distance between the portion of the left crawler frame to which the rear load is transmitted via the left rear connecting member and the rear end of the left crawler frame can be effectively reduced. This makes it possible to reduce deflection that occurs in the rear portions of the left and right crawler frames when a load is suspended from the upper rotating body rearward of the lower traveling body.

[0033] In addition, when the car body receives a relatively large rear load from the upper rotating body, the right rear end roller and the left rear end roller become approximate tipping fulcrums (rear tipping fulcrums), so it is preferable that the right rear straight line is a straight line passing through the right rear end roller in a planar view, and the left rear straight line is a straight line passing through the left rear end roller in a planar view.

[0034] In this aspect, the right rear connecting member and the left rear connecting member can directly transmit the rear load to the portions of the left and right crawler frames that correspond to the rear tipping fulcrums, making it possible to more effectively reduce deflection that occurs in the rear portions of the left and right crawler frames due to the rear load.

[0035] It is also more preferable that the right rear straight line is a straight line that further passes through the turning central axis in a plan view, and the left rear straight line is a straight line that further passes through the turning central axis in a plan view.

[0036] In this embodiment, any point on the right rear load receiving surface of the right rear connecting member and any point on the right rear load transfer surface of the right rear connecting member can be positioned on a right rear straight line passing through the turning center axis and the right rear end roller in a plan view, and any point on the left rear load receiving surface of the left rear connecting member and any point on the left rear load transfer surface of the left rear connecting member can be positioned on a left rear straight line passing through the turning center axis and the left rear end roller in a plan view. This makes it possible to approximate the path along which the rear load is transferred to the right crawler frame by the right rear connecting member to a direction from the turning center axis toward the right rear end roller, and to approximate the path along which the rear load is transferred to the left crawler frame by the left rear connecting member to a direction from the turning center axis toward the left rear end roller, so that the rear load is efficiently transferred to portions of the left and right crawler frames that correspond to the rear tipping fulcrums.

[0037] In the lower running body of the mobile crane, it is preferable that the right rear connecting member has a right rear continuing portion that continues from the right rear load receiving surface to the right rear load transfer surface along the right rear straight line in a planar view, and the left rear connecting member has a left rear continuing portion that continues from the left rear load receiving surface to the left rear load transfer surface along the left rear straight line in a planar view.

[0038] In this aspect, the right rear continuing portion continues without interruption from the right rear load receiving surface to the right rear load transfer surface along the right rear straight line in a planar view, and the left rear continuing portion continues without interruption from the left rear load receiving surface to the left rear load transfer surface along the left rear straight line in a planar view.Therefore, the rear load received by the right rear load receiving surface and the left rear load receiving surface is transmitted continuously and efficiently along the right rear continuing portion and the left rear continuing portion to the right rear load transfer surface and the left rear load transfer surface, and from these load transfer surfaces to the left and right crawler frames. Effect of the Invention

[0039] According to the present invention, a lower running body of a mobile crane is provided that can minimize deformation that occurs in the lower running body when a load is suspended from an upper rotating body in front of or behind the lower running body, while suppressing an increase in the dimensions of the components that make up the lower running body during transportation of the mobile crane, and suppressing a decrease in the ease of disassembly and assembly of the lower running body. [Brief description of the drawings]

[0040] [Figure 1] FIG. 1 is a side view showing an example of a mobile crane equipped with a lower traveling body according to a first embodiment. [Diagram 2] FIG. 2 is a perspective view showing a lower traveling body according to the first embodiment. [Diagram 3] FIG. 2 is a plan view showing a lower traveling body according to the first embodiment. [Figure 4] FIG. 2 is a front view showing a lower traveling body according to the first embodiment. [Diagram 5] FIG. 2 is a perspective view showing a left crawler frame, a left front connecting member, and a left rear connecting member of a lower traveling body according to the first embodiment. [Figure 6] FIG. 2 is a perspective view showing a left crawler frame, a left front connecting member, and a left rear connecting member of a lower traveling body according to the first embodiment. [Figure 7] FIG. 4 is a perspective view showing a connection structure between a crawler connection portion of a left rear connecting member of a lower traveling body according to the first embodiment and a connected portion of a left crawler frame. [Figure 8] FIG. 4 is a perspective view showing a connection structure between a crawler connection portion of a left rear connecting member of a lower traveling body according to the first embodiment and a connected portion of a left crawler frame. [Figure 9] FIG. 4 is a rear view showing the connection structure between the car body connecting portion of the left rear connecting member of the lower traveling body according to the first embodiment and the connected portion of the car body. [Figure 10] FIG. 4 is a rear view showing the connection structure between the car body connecting portion of the left rear connecting member of the lower traveling body according to the first embodiment and the connected portion of the car body. [Figure 11] FIG. 4 is a perspective view showing a connection structure between a left intermediate connecting portion of a car body of a lower traveling body and a left intermediate connected portion of a left crawler frame according to the first embodiment. [Figure 12] FIG. 4 is a rear view showing the connection structure between the left intermediate connecting portion of the car body of the lower traveling body and the left intermediate connected portion of the left crawler frame according to the first embodiment. [Figure 13] FIG. 11 is a plan view showing a lower traveling body according to a modified example of the first embodiment. [Figure 14] FIG. 11 is a plan view showing a lower traveling body according to the second embodiment. [Figure 15] FIG. 11 is a plan view showing a carbody and a plurality of connecting members of an undercarriage according to the second embodiment. [Figure 16] FIG. 11 is a front view showing a car body, a right front connecting member, and a left front connecting member of a lower traveling body according to the second embodiment. [Figure 17] FIG. 11 is a left side view showing a car body, a left front connecting member, and a left rear connecting member of a lower traveling body according to the second embodiment. [Figure 18] FIG. 11 is a front view showing a car body and a plurality of connecting members of a lower traveling body according to the second embodiment. [Figure 19]FIG. 11 is a side view showing a carbody and a plurality of connecting members of an undercarriage according to the second embodiment. [Figure 20] FIG. 11 is an enlarged plan view of a car body and a left rear connecting member of a lower traveling body according to the second embodiment. [Figure 21] FIG. 11 is a cross-sectional view showing a lower traveling body according to a modified example of the second embodiment. [Figure 22] FIG. 11 is a perspective view showing a car body, a connecting member, and a crawler frame of a lower traveling body according to a modified example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Below, the lower traveling body of the mobile crane according to the embodiment will be described with reference to the drawings. Note that in the drawings, the characters "front", "rear", "right", "left", "up" and "down" are written, but these are based on the direction in which the lower traveling body moves forward and backward. In other words, the front-to-rear direction of the lower traveling body is the horizontal direction in which the crawler frame described below extends, and the left-to-right direction of the lower traveling body is a horizontal direction perpendicular to the front-to-rear direction. The up-down direction of the lower traveling body is a direction parallel to the central axis of rotation of the upper rotating body.

[0042] [Overall structure of mobile crane] As shown in Fig. 1, the mobile crane 100 according to this embodiment includes a lower traveling body 101 and an upper rotating body 102. The lower traveling body 101 supports the upper rotating body 102 from below so as to be able to rotate, and is configured to be able to travel on the ground.

[0043] The upper rotating body 102 is disposed on the lower traveling body 101. The upper rotating body 102 includes a rotating frame 103, a working device, a cab 104, and a counterweight 105. The working device, the cab 104, and the counterweight 105 are mounted on the rotating frame 103.

[0044] The working device is for performing work such as lifting a load (crane work). In this embodiment, the working device includes a boom 106, a lifting winch 107, a lifting rope 108, a hook device 109, a gantry 110, a hoisting winch 111, a lower spreader 112, a hoisting rope 113, an upper spreader 114, and a guy line 115. The working device is not limited to the specific example shown in FIG. 1, and may further include, for example, a jib (not shown) that can be attached to the tip of the boom. In the specific example shown in FIG. 1, the boom 106 is a lattice boom having a lattice structure, but is not limited thereto, and may be a telescopic boom that can change its length by extending and contracting.

[0045] The boom 106 is attached to the front of the revolving frame 103 so as to be able to be raised and lowered, and a hook device 109 for hoisting a load is suspended from the tip of the boom 106 via a hoisting rope 108. The hoisting winch 107 is mounted on the revolving frame 103, and hoists or lowers the hook device 109 by winding or unwinding the hoisting rope 108. The gantry 110 is erected on the rear of the revolving frame 103. One end of the guy line 115 is connected to the tip of the boom 106, and the other end is connected to the upper spreader 114. The lower spreader 112 is provided at the upper end of the gantry 110, and the lower spreader 112 and the upper spreader 114 are arranged at a distance from each other. A hoisting rope 113 is wound around the lower spreader 112 and the upper spreader 114. The hoisting winch 111 is mounted on the revolving frame 103, and winds or unwinds the hoisting rope 113 to reduce or increase the distance between the lower spreader 112 and the upper spreader 114. As the distance between the spreaders 112, 114 decreases or increases, the boom 106 is hoisted.

[0046] [Structure of the lower running body according to the first embodiment] FIG. 2 is a perspective view showing the lower traveling body 101 according to the first embodiment, and FIG. 3 is a plan view thereof. In this embodiment, as shown in FIG. 1 and FIG. 3, the front-rear direction of the lower traveling body 101 is the longitudinal direction of the crawler frames 2R, 2L described later, and the front of the front-rear direction is the direction from the wheel 24R (drive tumbler) to the wheel 23R (idler) of each crawler frame, and the rear is the opposite direction. However, the front-rear direction of the lower traveling body 101 may be defined as the opposite direction to the direction defined in FIG. 2 and FIG. 3. Note that the wheels 23R, 24R are not shown in FIG. 2.

[0047] The lower traveling body 101 includes the car body 10, a swivel bearing 19 supported on the upper part of the car body 10, a right traveling device, a left traveling device, and a plurality of connecting members.

[0048] The carbody 10 supports an upper rotating body 102 of the mobile crane 100 so as to be rotatable about a central axis of rotation C via a slewing bearing 19. The upper rotating body 102 is mounted on the slewing bearing 19. When the ground is horizontal, the central axis of rotation C is approximately parallel to the vertical direction.

[0049] In this embodiment, the car body 10 includes a car body main body 10A having a substantially rectangular parallelepiped shape, a right axle 13R, and a left axle 13L. The car body 10 has a plurality of connected parts. A swivel bearing 19 is attached to the car body main body 10A. The shape of the car body main body 10A is not limited to a substantially rectangular parallelepiped shape. The plurality of connected parts will be described later.

[0050] Each of the right and left traveling devices is a device for traveling on the ground while supporting the car body 10. The right traveling device includes a right crawler frame 2R, a pair of right wheels 23R, 24R, a right crawler belt 25R, a plurality of right rollers 26, and a traveling drive device 29 (see FIG. 1). Similarly, the left traveling device includes a left crawler frame 2L, a pair of left wheels 23L, 24L, a left crawler belt 25L, a plurality of left rollers 26, and a traveling drive device 29.

[0051] The right crawler frame 2R includes a right frame main body 20R and multiple connected parts, and the left crawler frame 2L includes a left frame main body 20L and multiple connected parts. The right frame main body 20R has a shape extending in the front-rear direction to the right of the turning center axis C. The left frame main body 20L has a shape extending in the front-rear direction to the left of the turning center axis C. The multiple connected parts will be described later.

[0052] A pair of right wheels 23R, 24R are rotatably supported at the front end and rear end of the right frame main body 20R, respectively. In this embodiment, the right wheel 23R located on the front side is constituted by an idler, and the right wheel 24R located on the rear side is constituted by a drive tumbler. This drive tumbler is connected to a traveling drive device 29 (see FIG. 1) supported at the rear end of the right frame main body 20R at a position adjacent to the drive tumbler. The traveling drive device 29 includes, for example, a traveling motor and a traveling reducer. Note that the traveling drive device 29 is omitted from illustrations other than FIG. 1.

[0053] The right crawler belt 25R is a belt that is looped around the pair of right wheels 23R, 24R and can move around. In other words, the right crawler belt 25R is supported endlessly by the pair of right wheels 23R, 24R. The right crawler belt 25R is configured by connecting a number of crawler shoes.

[0054] The right wheel 24R, which is made of a drive tumbler, has a plurality of protrusions formed on its outer periphery along the circumferential direction so as to be engageable with the inner periphery of the right crawler belt 25R. The right wheel 24R is given a driving force from the travel drive device 29, and this driving force is transmitted to the right crawler belt 25R. This causes the right crawler belt 25R to move in an orbit. The right wheel 23R, which is made of an idler, rotates following the rotation of the right crawler belt 25R.

[0055] The right rollers 26 are each rotatably supported at a lower portion of the right frame main body 20R of the right crawler frame 2R. The right rollers 26 are disposed at intervals in the front-rear direction between the pair of right wheels 23R, 24R. The right rollers 26 press the right crawler belt 25R against the ground and guide the circular movement of the right crawler belt 25R.

[0056] In the following, the right roller 26 located furthest from the multiple right rollers 26 (in this embodiment, the right roller 26 closest to wheel 23R) will be referred to as the right front end roller 261, and the right roller 26 located furthest from the multiple right rollers 26 (in this embodiment, the right roller 26 closest to wheel 24R) will be referred to as the right rear end roller 262.

[0057] The structure of the pair of left wheels 23L, 24L, left crawler belt 25L, and multiple left rollers 26 in the left traveling device is similar to the structure of the pair of right wheels 23R, 24R, right crawler belt 25R, and multiple right rollers 26 in the right traveling device described above, except for the fact that they are symmetrical, so detailed explanations will be omitted. In the following, the left roller 26 located furthest from the multiple left rollers 26 (in this embodiment, the left roller 26 closest to the wheel 23L) will be referred to as the left front end roller 261, and the left roller 26 located furthest from the multiple left rollers 26 (in this embodiment, the left roller 26 closest to the wheel 24L) will be referred to as the left rear end roller 262.

[0058] The right axle 13R extends from the right side of the car body 10A to the right, connecting the car body 10A to the right crawler frame 2R. The left axle 13L extends from the left side of the car body 10A to the left, connecting the car body 10A to the left crawler frame 2L.

[0059] In this embodiment, the location where the right axle 13R is connected to the right frame body 20R is near the center in the fore-aft direction of the right frame body 20R, and the location where the left axle 13L is connected to the left frame body 20L is near the center in the fore-aft direction of the left frame body 20L, but each of these locations may be shifted in the fore-aft direction from the center.

[0060] In this embodiment, the right axle 13R has a tapered shape in which the width in the front-rear direction decreases toward the right frame main body 20R, and the left axle 13L has a tapered shape in which the width in the front-rear direction decreases toward the left frame main body 20L, but the shapes of the right axle 13R and the left axle 13L are not limited to tapered shapes. For example, the right axle 13R may have a shape in which the width in the front-rear direction is almost constant from the base end connected to the car body main body 10A to the tip end connected to the right frame main body 20R, and the left axle 13L may have a shape in which the width in the front-rear direction is almost constant from the base end connected to the car body main body 10A to the tip end connected to the left frame main body 20L.

[0061] In addition, the car body 10 composed of the car body main body 10A, the right axle 13R, and the left axle 13L may be composed of a single member as shown in Figure 2, or the car body main body 10A, the right axle 13R, and the left axle 13L may be manufactured separately and then connected to each other.

[0062] The multiple connecting members include a right front connecting member 11R, a right rear connecting member 12R, a left front connecting member 11L, and a left rear connecting member 12L.

[0063] The right front coupling member 11R has a shape extending diagonally forward and to the right from the car body 10 in front of the turning center axis C, and couples the car body 10 to the right crawler frame 2R. The right rear coupling member 12R has a shape extending diagonally rear and to the right from the car body 10 in rear of the turning center axis C, and couples the car body 10 to the right crawler frame 2R. The right axle 13R is disposed rearward of the right front coupling member 11R and forward of the right rear coupling member 12R. That is, the right front coupling member 11R, the right axle 13R, and the right rear coupling member 12R are disposed in this order with a gap between them in the front-rear direction.

[0064] The left front connecting member 11L has a shape extending diagonally forward and left from the car body 10 forward of the turning center axis C, and connects the car body 10 and the left crawler frame 2L. The left rear connecting member 12L has a shape extending diagonally rear and left from the car body 10 rear of the turning center axis C, and connects the car body 10 and the left crawler frame 2L. The left axle 13L is disposed rearward of the left front connecting member 11L and forward of the left rear connecting member 12L. That is, the left front connecting member 11L, the left axle 13L, and the left rear connecting member 12L are disposed in this order with a gap between them in the front-rear direction.

[0065] [Connection structure] We will describe the connection structure for connecting each of the multiple connecting members 11R, 12R, 11L, 12L to the car body 10 and the crawler frame, the connection structure for connecting the right axle 13R to the right crawler frame 2R, and the connection structure for connecting the left axle 13L to the left crawler frame 2L.

[0066] As described above, the car body 10 includes a plurality of connected portions. The plurality of connected portions include the right front connected portion 51R, the right rear connected portion 52R, the left front connected portion 51L, and the left rear connected portion 52L.

[0067] The right front connected portion 51R is a portion to which the right front coupling member 11R is connected, and is provided in a portion of the car body main body 10A that is forward of the right axle 13R and to the right of the turning center axis C. In this embodiment, the right front connected portion 51R is provided in a front portion of the right side surface of the car body main body 10A, but may be provided, for example, in a right portion of the front surface of the car body main body 10A.

[0068] The right rear connected portion 52R is a portion to which the right rear coupling member 12R is connected, and is provided in a portion of the car body main body 10A rearward of the right axle 13R and to the right of the turning center axis C. In this embodiment, the right rear connected portion 52R is provided in a rear portion of the right side surface of the car body main body 10A, but may be provided, for example, in a right portion of the rear surface of the car body main body 10A.

[0069] The left front connected portion 51L is a portion to which the left front coupling member 11L is connected, and is provided in a portion of the car body main body 10A that is forward of the left axle 13L and to the left of the turning center axis C. In this embodiment, the left front connected portion 51L is provided in a front portion of the left side surface of the car body main body 10A, but may be provided, for example, in a left portion of the front surface of the car body main body 10A.

[0070] The left rear connected portion 52L is a portion to which the left rear coupling member 12L is connected, and is provided in a portion of the car body main body 10A rearward of the left axle 13L and to the left of the turning center axis C. In this embodiment, the left rear connected portion 52L is provided in a rear portion of the left side surface of the car body main body 10A, but may be provided, for example, in a left portion of the rear surface of the car body main body 10A.

[0071] As described above, the right crawler frame 2R includes a plurality of connected portions. The connected portions include a right front connected portion 61R, a right rear connected portion 62R, and a right intermediate connected portion 63R.

[0072] The right intermediate connected part 63R is a part to which the right axle 13R of the car body 10 is connected, and is provided in a portion of the right frame main body 20R whose position in the front-rear direction corresponds to the right axle 13R. In this embodiment, the right intermediate connected part 63R is provided near the center in the front-rear direction of the right frame main body 20R.

[0073] The right front connected portion 61R is a portion to which the right front coupling member 11R is connected, and is provided in a portion of the right frame main body 20R forward of the right intermediate connected portion 63R. As shown in Fig. 3, the right front connected portion 61R of the right crawler frame 2R is disposed diagonally to the right of the right front connected portion 51R of the car body 10.

[0074] The right rear connected part 62R is a portion to which the right rear coupling member 12R is connected, and is provided at a portion of the right frame main body 20R rearward of the right intermediate connected part 63R. As shown in Fig. 3, the right rear connected part 62R of the right crawler frame 2R is disposed diagonally to the right rear of the right rear connected part 52R of the car body 10.

[0075] As described above, the left crawler frame 2L includes a plurality of connected portions. The connected portions include a left front connected portion 61L, a left rear connected portion 62L, and a left middle connected portion 63L.

[0076] The left intermediate connected part 63L is a part to which the left axle 13L of the car body 10 is connected, and is provided in a portion of the left frame main body 20L whose position in the front-rear direction corresponds to the left axle 13L. In this embodiment, the left intermediate connected part 63L is provided near the center of the left frame main body 20L in the front-rear direction.

[0077] The left front connected part 61L is a part to which the left front coupling member 11L is connected, and is provided in a portion of the left frame main body 20L forward of the left intermediate connected part 63L. As shown in Fig. 3, the left front connected part 61L of the left crawler frame 2L is disposed diagonally to the right in front of the left front connected part 51L of the car body 10.

[0078] The left rear connected part 62L is a portion to which the left rear coupling member 12L is connected, and is provided at a position rearward of the left intermediate connected part 63L in the left frame main body 20L. As shown in Fig. 3, the left rear connected part 62L of the left crawler frame 2L is disposed diagonally left rear of the left rear connected part 52L of the car body 10.

[0079] The right axle 13R has a right intermediate connecting part 43R that is detachably connected to the right intermediate connected part 63R of the right crawler frame 2R, and an axle main body 73R that connects the right intermediate connecting part 43R and the car body main body 10A. The right intermediate connecting part 43R constitutes the tip part of the right axle 13R. The axle main body 73R is a part that has a shape that extends to the right side from the car body main body 10A, and occupies the majority of the right axle 13R.

[0080] The left axle 13L has a left intermediate connecting part 43L that is detachably connected to the left intermediate connected part 63L of the left crawler frame 2L, and an axle body 73L that connects the left intermediate connecting part 43L and the car body main body 10A. The left intermediate connecting part 43L forms the tip part of the left axle 13L. The axle body 73L is a part that has a shape that extends leftward from the car body main body 10A, and occupies the majority of the left axle 13L.

[0081] The right front connecting member 11R has a car body connecting part 31R connected to the right front connected part 51R of the car body 10, a crawler connecting part 41R connected to the right front connected part 61R of the right crawler frame 2R, and a connecting member main body 71R connecting the car body connecting part 31R and the crawler connecting part 41R. The right front connecting member 11R connects the car body 10 and the right crawler frame 2R at a protruding position where the crawler connecting part 41R is located diagonally forward to the right of the car body connecting part 31R. The car body connecting part 31R constitutes the base end part of the right front connecting member 11R, and the crawler connecting part 41R constitutes the tip part of the right front connecting member 11R. The connecting member main body 71R is a part that is arranged in a posture extending diagonally forward to the right when the right front connecting member 11R is arranged at the protruding position, and occupies the majority of the right front connecting member 11R.

[0082] The right rear coupling member 12R has a car body connection part 32R connected to the right rear connected part 52R of the car body 10, a crawler connection part 42R connected to the right rear connected part 62R of the right crawler frame 2R, and a coupling member main body 72R connecting the car body connection part 32R and the crawler connection part 42R. The right rear coupling member 12R couples the car body 10 and the right crawler frame 2R at a protruding position where the crawler connection part 42R is located diagonally to the right rear of the car body connection part 32R. The car body connection part 32R constitutes the base end part of the right rear coupling member 12R, and the crawler connection part 42R constitutes the tip part of the right rear coupling member 12R. The coupling member main body 72R is a part that is arranged in a posture that extends diagonally to the right rear when the right rear coupling member 12R is arranged at the protruding position, and occupies the majority of the right rear coupling member 12R.

[0083] The left front connecting member 11L has a car body connecting part 31L connected to the left front connected part 51L of the car body 10, a crawler connecting part 41L connected to the left front connected part 61L of the left crawler frame 2L, and a connecting member main body 71L connecting the car body connecting part 31L and the crawler connecting part 41L. The left front connecting member 11L connects the car body 10 and the left crawler frame 2L at a protruding position where the crawler connecting part 41L is located diagonally forward to the left of the car body connecting part 31L. The car body connecting part 31L constitutes the base end part of the left front connecting member 11L, and the crawler connecting part 41L constitutes the tip part of the left front connecting member 11L. The connecting member main body 71L is a part that is arranged in a posture that extends diagonally forward to the left when the left front connecting member 11L is arranged at the protruding position, and occupies the majority of the left front connecting member 11L.

[0084] The left rear connecting member 12L has a car body connecting part 32L connected to the left rear connected part 52L of the car body 10, a crawler connecting part 42L connected to the left rear connected part 62L of the left crawler frame 2L, and a connecting member main body 72L connecting the car body connecting part 32L and the crawler connecting part 42L. The left rear connecting member 12L connects the car body 10 and the left crawler frame 2L at a protruding position where the crawler connecting part 42L is located diagonally left rear of the car body connecting part 32L. The car body connecting part 32L constitutes the base end of the left rear connecting member 12L, and the crawler connecting part 42L constitutes the tip end of the left rear connecting member 12L. The connecting member main body 72L is a part that is arranged in a posture that extends diagonally left rear when the left rear connecting member 12L is arranged at the protruding position, and occupies the majority of the left rear connecting member 12L.

[0085] In this embodiment, in the multiple connecting members 11R, 12R, 11L, 12L, the car body connection parts 31R, 32R, 31L, 32L are detachable connection parts, the crawler connection parts 41R, 42R, 41L, 42L are rotating connection parts, the car body 10 is a detachable member, and each of the right crawler frame 2R and the left crawler frame 2L is a rotated member.

[0086] The car body connection portion 31R of the right front coupling member 11R is detachably connected to the right front connected portion 51R of the car body 10, and the crawler connection portion 41R of the right front coupling member 11R is rotatably connected to the right front connected portion 61R of the right crawler frame 2R.

[0087] The car body connecting portion 32R of the right rear coupling member 12R is detachably connected to the right rear connected portion 52R of the car body 10, and the crawler connecting portion 42R of the right rear coupling member 12R is rotatably connected to the right rear connected portion 62R of the right crawler frame 2R.

[0088] The car body connection portion 31L of the left front coupling member 11L is detachably connected to the left front connected portion 51L of the car body 10, and the crawler connection portion 41L of the left front coupling member 11L is rotatably connected to the left front connected portion 61L of the left crawler frame 2L.

[0089] The car body connecting portion 32L of the left rear coupling member 12L is detachably connected to the left rear connected portion 52L of the car body 10, and the crawler connecting portion 42L of the left rear coupling member 12L is rotatably connected to the left rear connected portion 62L of the left crawler frame 2L.

[0090] Each of the multiple connecting members 11R, 12R, 11L, and 12L having the above-mentioned connection structure is configured to be displaceable between an extended state in which the connecting members are disposed at the extended positions shown in Fig. 2, Fig. 3, and Fig. 5, and a close state in which the connecting members are disposed at the close position shown in Fig. 6. That is, each of the multiple connecting members 11R, 12R, 11L, and 12L is configured to be disposed at a close position in which the connecting members are located closer to the corresponding crawler frame (rotatable member) than the extended position by rotating at the crawler connecting portion (rotatable connecting portion) in a state in which the car body connecting portion (detachable connecting portion) is detached from the car body 10 (detachable member). A specific description will be given below using the left front connecting member 11L and the left rear connecting member 12L as an example.

[0091] 2 and 3 show a state in which the car body connecting part 31L of the left front coupling member 11L is connected to the left front connected part 51L of the car body 10, the car body connecting part 32L of the left rear coupling member 12L is connected to the left rear connected part 52L of the car body 10, and the left intermediate connecting part 43L of the left axle 13L is connected to the left intermediate connected part 63L of the left crawler frame 2L. In the state shown in Fig. 2 and Fig. 3, the left front coupling member 11L is disposed at a projecting position in which the crawler connecting part 41L is located diagonally left forward of the car body connecting part 31L, and the left rear coupling member 12L is disposed at a projecting position in which the crawler connecting part 42L is located diagonally left rear of the car body connecting part 32L.

[0092] 5 shows a state in which the car body connecting portion 31L of the left front coupling member 11L is removed from the left front connected portion 51L of the car body 10, the car body connecting portion 32L of the left rear coupling member 12L is removed from the left rear connected portion 52L of the car body 10, and the left intermediate connecting portion 43L of the left axle 13L is removed from the left intermediate connected portion 63L of the left crawler frame 2L. In the state shown in FIG. 5, the crawler connecting portion 41L of the left front coupling member 11L remains connected to the left front connected portion 61L of the left crawler frame 2L, the crawler connecting portion 42L of the left rear coupling member 12L remains connected to the left rear connected portion 62L of the left crawler frame 2L, and each of the left front coupling member 11L and the left rear coupling member 12L remains disposed in the protruding position.

[0093] Fig. 6 shows a state in which the left front connecting member 11L is disposed at the approaching position by rotating about the rotation center axis CA of the crawler connection part 41L from the extended position shown in Fig. 5, and the left rear connecting member 12L is disposed at the approaching position by rotating about the rotation center axis CA of the crawler connection part 42L from the extended position shown in Fig. 5. In this embodiment, the rotation center axes CA are parallel to the up-down direction. In the state shown in Fig. 6, the crawler connection part 41L of the left front connecting member 11L remains connected to the left front connected part 61L of the left crawler frame 2L, and the crawler connection part 42L of the left rear connecting member 12L remains connected to the left rear connected part 62L of the left crawler frame 2L.

[0094] 6, the car body connecting portion 31L of the left front connecting member 11L and the car body connecting portion 32L of the left rear connecting member 12L are located closer to the left frame main body 20L of the left crawler frame 2L than they are in the extended position.

[0095] As shown in Fig. 6, the left front connecting member 11L is arranged to extend rearward from the crawler connection part 41L along the left frame main body 20L at the approaching position, and the left rear connecting member 12L is arranged to extend forward from the crawler connection part 42L along the left frame main body 20L at the approaching position. In other words, the left front connecting member 11L is arranged so that the car body connection part 31L is adjacent to the left frame main body 20L at the approaching position, and the left rear connecting member 12L is arranged so that the car body connection part 32L is adjacent to the left frame main body 20L at the approaching position. This makes it possible to effectively prevent an increase in the dimensions (width in the left-right direction in Fig. 6) of the parts including the left crawler frame 2L, the left front connecting member 11L, and the left rear connecting member 12L during transportation of the mobile crane 100.

[0096] In this embodiment, the left front coupling member 11L is disposed at the approaching position shown in FIG. 6 by rotating clockwise in a plan view from the extended position shown in FIG. 5, and at this approaching position, the car body connection part 31L is located on the rear side of the crawler connection part 41L, and the left rear coupling member 12L is disposed at the approaching position shown in FIG. 6 by rotating counterclockwise in a plan view from the extended position shown in FIG. 5, and at this approaching position, the car body connection part 32L is located on the front side of the crawler connection part 42L. However, this is not limited to such an embodiment. The left front coupling member 11L is disposed at the approaching position by rotating counterclockwise in a plan view from the extended position, and at this approaching position, the car body connection part 31L may be located on the front side of the crawler connection part 41L. Similarly, the left rear coupling member 12L is disposed at the approaching position by rotating clockwise in a plan view from the extended position, and at this approaching position, the car body connection part 32L may be located on the rear side of the crawler connection part 42L.

[0097] In this embodiment, as shown in FIG. 6, at least a part of the car body connection part 31L of the left front connecting member 11L is stored in a storage space defined by the right side surface 20S of the left frame main body 20L, the lower surface of the upper part of the left crawler belt 25L, and the upper surface of the lower part of the left crawler belt 25L. In other words, at least a part of the car body connection part 31L of the left front connecting member 11L is arranged in a position overlapping the left crawler belt 25L in a plan view. Similarly, at least a part of the car body connection part 32L of the left rear connecting member 12L is stored in a storage space defined by the right side surface of the left frame main body 20L, the lower surface of the upper part of the left crawler belt 25L, and the upper surface of the lower part of the left crawler belt 25L. In other words, at least a part of the car body connection part 32L of the left rear connecting member 12L is arranged in a position overlapping the left crawler belt 25L in a plan view. This effectively prevents an increase in the dimensions (left-right width in Figure 6) of parts including the left crawler frame 2L, left crawler belt 25L, left front connecting member 11L, and left rear connecting member 12L when transporting the mobile crane 100.

[0098] The right front connecting member 11R and the right rear connecting member 12R are each configured to be displaceable between a projecting position and a close position. The structures for displacing the right front connecting member 11R and the right rear connecting member 12R between the projecting position and the close position are the same as those of the left front connecting member 11L and the left rear connecting member 12L described with reference to Figures 5 and 6, except that the orientation in the left-right direction is different, so a description thereof will be omitted.

[0099] The main features of the lower traveling body 101 according to the first embodiment have been described above, and a specific example of the connection structure will be described below. Note that the connection structure is not limited to the specific example described below, and various aspects can be adopted.

[0100] First, a connection structure between each of the crawler connecting parts of the multiple connecting members 11R, 12R, 11L, 12L and the crawler frame will be described. Each of Fig. 7 and Fig. 8 is a perspective view showing a connection structure between the crawler connecting part 42L of the left rear connecting member 12L of the lower traveling body 101 according to the first embodiment and the connected part 62L of the left crawler frame 2L.

[0101] 7 and 8, the crawler connection part 42L of the left rear connecting member 12L is formed by the tip part of the left rear connecting member 12L. The crawler connection part 42L has a pin insertion hole H11 that passes through the crawler connection part 42L in the up-down direction.

[0102] The connected portion 62L of the left crawler frame 2L has a pair of protruding pieces PL1 that protrude rightward from the right side surface 20S (inner surface) of the left frame main body 20L. These protruding pieces PL1 are arranged at a distance from each other in the vertical direction. The vertical distance (gap) between the pair of protruding pieces PL1 is set to a value slightly larger than the vertical dimension (thickness) of the crawler connecting portion 42L of the left rear coupling member 12L so that the crawler connecting portion 42L can fit between them.

[0103] Each of the pair of protruding pieces PL1 has a pin insertion hole H12 at a position corresponding to the pin insertion hole H11 of the crawler connection part 42L. When the crawler connection part 42L is fitted between the pair of protruding pieces PL1, the pin insertion hole H12 of each of the pair of protruding pieces PL1 is disposed at the same position as the pin insertion hole H11 of the crawler connection part 42L in a plan view. With the crawler connection part 42L of the left rear connecting member 12L fitted between the pair of protruding pieces PL1, the pin P11 is inserted into the pin insertion hole H11 of the crawler connection part 42L and the pin insertion hole H12 of each of the pair of protruding pieces PL1. As a result, the crawler connection part 42L of the left rear connecting member 12L is rotatably connected to the connected part 62L of the left crawler frame 2L. The left rear connecting member 12L can rotate around the rotation center axis CA, which is the center of the pin P11, relative to the connected part 62L of the left crawler frame 2L. The range in which the left rear connecting member 12L can rotate includes the extended position shown in FIGS. 2, 3, 5 and 7, and the close position shown in FIGS.

[0104] The connection structure between the crawler connection portion 41R of the right front connecting member 11R and the connected portion 61R of the right crawler frame 2R, the connection structure between the crawler connection portion 42R of the right rear connecting member 12R and the connected portion 62R of the right crawler frame 2R, and the connection structure between the crawler connection portion 41L of the left front connecting member 11L and the connected portion 61L of the left crawler frame 2L are similar to the connection structure between the crawler connection portion 42L of the left rear connecting member 12L and the connected portion 62L of the left crawler frame 2L described with reference to Figures 7 and 8, except for the orientation, so detailed explanations will be omitted.

[0105] Next, a fixing structure for temporarily fixing each of the plurality of connecting members 11R, 12R, 11L, and 12L to the extended position and the close position will be described.

[0106] The lower traveling body 101 according to this embodiment further includes a plurality of fixing members P21 for fixing each of the plurality of connecting members 11R, 12R, 11L, 12L to the extended position and the approaching position, respectively.

[0107] In this embodiment, the multiple fixing members P21 are multiple extension position fixing members and multiple approach position fixing members. That is, each fixing member P21 has both a function as an extension position fixing member and a function as an approach position fixing member. The extension position fixing member is a member for temporarily fixing the connecting member to the extension position, and the approach position fixing member is a member for temporarily fixing the connecting member to the approach position. However, the extension position fixing member and the approach position fixing member may be composed of different members.

[0108] Below, with reference to Figures 7 and 8, we will explain the fixing structures for fixing the left rear connecting member 12L to the extended position and the close position, respectively. However, the fixing structures of the right front connecting member 11R, the right rear connecting member 12R and the left front connecting member 11L are similar to the fixing structure of the left rear connecting member 12L except that the orientation is different.

[0109] As shown in FIG. 7, the tip of the left rear connecting member 12L constituting the crawler connection part 42L of the left rear connecting member 12L has two pin insertion holes H21, H22 drilled downward from the upper surface of the tip. In this embodiment, each of the two pin insertion holes H21, H22 is a hole having a bottom in the middle part in the height direction of the crawler connection part 42L, but may be a through hole that penetrates the crawler connection part 42L in the vertical direction. The two pin insertion holes H21, H22 are provided on the same arc centered on the rotation central axis CA in a plan view. One pin insertion hole H21 is provided in a position farther from the left frame main body 20L of the left crawler frame 2L than the other pin insertion hole H22.

[0110] Of the pair of protrusions PL1 constituting the connected part 62L of the left crawler frame 2L, the upper protrusion PL1 has a pin insertion hole H23 that passes through the protrusion PL1 in the vertical direction. In a plan view, the pin insertion hole H23 of the protrusion PL1 is provided on the same arc that is centered on the rotation central axis CA and on which the two pin insertion holes H21, H22 of the crawler connection part 42L are provided.

[0111] When the left rear connecting member 12L is positioned in the extended position shown in Figure 7, the pin insertion hole H23 of the protrusion piece PL1 is positioned in the same position as one of the pin insertion holes H21 of the crawler connection part 42L in a planar view, and when the left rear connecting member 12L is positioned in the close position shown in Figure 8, the pin insertion hole H23 of the protrusion piece PL1 is positioned in the same position as the other pin insertion hole H22 of the crawler connection part 42L in a planar view.

[0112] In this embodiment, the fixing member P21 is configured by a pin. With the left rear connecting member 12L disposed in the extended position shown in FIG. 7, the fixing member P21 is inserted into the pin insertion hole H23 of the protruding piece PL1 and one of the pin insertion holes H21 of the crawler connecting part 42L. This restricts the left rear connecting member 12L from rotating relative to the connected part 62L of the left crawler frame 2L, and the left rear connecting member 12L is fixed to the extended position. When the fixing member P21 is removed from the pin insertion hole H23 of the protruding piece PL1 and one of the pin insertion holes H21 of the crawler connecting part 42L, the left rear connecting member 12L becomes able to rotate relative to the connected part 62L of the left crawler frame 2L.

[0113] With the left rear connecting member 12L disposed in the close position shown in Fig. 8, the fixing member P21 is inserted into the pin insertion hole H23 of the protruding piece PL1 and the other pin insertion hole H22 of the crawler connecting part 42L. This restricts the left rear connecting member 12L from rotating relative to the connected part 62L of the left crawler frame 2L, and fixes the left rear connecting member 12L to the close position. When the fixing member P21 is removed from the pin insertion hole H23 of the protruding piece PL1 and one of the pin insertion holes H21 of the crawler connecting part 42L, the left rear connecting member 12L becomes able to rotate relative to the connected part 62L of the left crawler frame 2L.

[0114] In the lower traveling body 101 according to this embodiment having such a fixing structure, in the assembly work of assembling the lower traveling body 101, the multiple connecting members 11R, 12R, 11L, and 12L are fixed to the protruding position by the multiple fixing members P21, and then the car body connection part of each connecting member is attached to the connected part of the car body 10. This improves the workability of the assembly work of the lower traveling body 101. Also, during transportation of the mobile crane, the multiple connecting members 11R, 12R, 11L, and 12L are fixed to the close position by the multiple fixing members P21, and thus are prevented from being displaced with respect to the corresponding crawler frames of the left and right crawler frames 2R and 2L.

[0115] Next, a connection structure between each of the car body connecting parts of the multiple connecting members 11R, 12R, 11L, and 12L and the car body 10 will be described. Each of Figures 9 and 10 is a rear view showing the connection structure between the car body connecting part 32L of the left rear connecting member 12L of the lower running body 101 and the connected part 52L of the car body 10.

[0116] As shown in Figs. 9 and 10, the car body connecting portion 32L of the left rear connecting member 12L is formed by the base end portion of the left rear connecting member 12L. The car body connecting portion 32L has a pair of protruding pieces PL2 protruding from a wall portion W1 constituting the base end portion of the connecting member main body 72L of the left rear connecting member 12L, and a rod-shaped engaging portion E1 arranged to straddle between the protruding pieces PL2 and supported by the protruding pieces PL2. The direction in which the pair of protruding pieces PL2 protrude from the wall portion W1 is the right side, that is, the direction approaching the car body main body 10A when the left rear connecting member 12L is disposed in the extended position shown in Fig. 5. The pair of protruding pieces PL2 are disposed at an interval from each other in the front-rear direction. The distance (gap) between the pair of protruding pieces PL2 in the front-rear direction is set to a value slightly larger than the dimension (thickness) in the front-rear direction of the protruding pieces PL3 described later constituting the connected portion 52L of the car body 10 so that the protruding pieces PL3 can be fitted between them. Each of the pair of projections PL2 has a pin insertion hole H31. The engagement portion E1 is provided above the pin insertion hole H31.

[0117] The connected portion 52L of the car body 10 has a protruding piece PL3 protruding leftward from a wall W2 constituting the front portion of the right side of the car body main body 10A. The protruding piece PL3 has a pin insertion hole H32 provided at a position corresponding to the pin insertion hole H31, and an engaged portion E2 provided at a position corresponding to the engaging portion E1. The engaged portion E2 has a concave shape with an open upper portion.

[0118] The rod-shaped engaging portion E1 is arranged in the engaged portion E2 through an opening of the engaged portion E2, so that it can engage with the engaged portion E2. As shown in Fig. 10, in a state in which the engaging portion E1 of the car body connecting portion 32L of the left rear connecting member 12L is engaged with the engaged portion E2 of the connected portion 52L of the car body 10, the pin P31 is inserted into the pin insertion holes H31 and H32. In this way, the car body connecting portion 32L of the left rear connecting member 12L is detachably connected to the connected portion 52L of the car body 10. When the car body connecting portion 32L of the left rear connecting member 12L is removed from the connected portion 52L of the car body 10 to transport the mobile crane 100, the above-mentioned procedure is reversed.

[0119] The connection structure between the car body connecting portion 31R of the right front connecting member 11R and the connected portion 51R of the car body 10, the connection structure between the car body connecting portion 32R of the right rear connecting member 12R and the connected portion 52R of the car body 10, and the connection structure between the car body connecting portion 31L of the left front connecting member 11L and the connected portion 51L of the car body 10 are similar to the connection structure between the car body connecting portion 32L of the left rear connecting member 12L and the connected portion 52L of the car body 10 described with reference to Figures 9 and 10 except for the orientation, so detailed explanations will be omitted.

[0120] Next, a connection structure between the right intermediate connecting part 43R of the right axle 13R and the right intermediate connected part 63R of the right crawler frame 2R, and a connection structure between the left intermediate connecting part 43L of the left axle 13L and the left intermediate connected part 63L of the left crawler frame 2L will be described. Fig. 11 is a perspective view showing the connection structure between the left intermediate connecting part 43L of the left axle 13L and the left intermediate connected part 63L of the left crawler frame 2L in the car body 10, and Fig. 12 is a rear view thereof.

[0121] 5, 11 and 12, the left intermediate connected portion 63L of the left crawler frame 2L has a pair of protruding pieces PL5 that protrude rightward from the left frame main body 20L of the left crawler frame 2L, and a rod-shaped engaging portion E3 that is disposed between and supported by the protruding pieces PL5. Each of the pair of protruding pieces PL5 has a pin insertion hole H42. The engaging portion E3 is provided above the pin insertion hole H42.

[0122] The left intermediate connection part 43L of the left axle 13L has a protruding piece PL4 that protrudes leftward from a wall part W3 that constitutes the left end part of the axle body 73L of the left axle 13L. The protruding piece PL4 has a pin insertion hole H41 and an engaged part E4. The engaged part E4 has a concave shape that is open at the top.

[0123] The rod-shaped engaging portion E3 is configured to be able to engage with the engaged portion E4 by being disposed within the engaged portion E4 through an opening of the engaged portion E4. As shown in Fig. 12, with the engaging portion E3 of the left crawler frame 2L engaged with the engaged portion E4 of the left axle 13L, a pin P41 is inserted through the pin insertion holes H41, H42. This connects the left intermediate connecting portion 43L of the left axle 13L to the left intermediate connected portion 63L of the left crawler frame 2L. When the left crawler frame 2L is removed from the left axle 13L in order to transport the mobile crane 100, the above-mentioned procedures are reversed.

[0124] The connection structure between the right intermediate connecting portion 43R of the right axle 13R and the right intermediate connected portion 63R of the right crawler frame 2R is similar to the connection structure shown in Figures 11 and 12, so a description thereof will be omitted.

[0125] In addition, four translifters TL are shown by two-dot chain lines TL in Fig. 3. As shown in Fig. 3, the lower traveling body 101 is provided with first to fourth translifters TL that can hold the carbody 10 above the ground during the assembly and disassembly of the mobile crane 100.

[0126] In assembling the mobile crane 100, the carbody 10 is held above the ground by the first to fourth transformer lifters TL. In this state, multiple connecting members 11R, 12R, 11L, 12L are connected to the carbody 10. After that, the right crawler frame 2R is connected to the right front connecting member 11R, the right rear connecting member 12R, and the right axle 13R, and the left crawler frame 2L is connected to the left front connecting member 11L, the left rear connecting member 12L, and the left axle 13L. Disassembly of the mobile crane 100 is performed in the reverse order of the above assembly work.

[0127] [Load transfer structure] Next, a load transfer structure provided on the lower running body 101 will be described in detail.

[0128] 3, the car body 10 has a plurality of load transfer surfaces for transferring the load received from the upper rotating body 102 to the plurality of connecting members 11R, 12R, 11L, and 12L, respectively. Specifically, the plurality of load transfer surfaces include a right front load transfer surface 5FR for transferring the load to the right front connecting member 11R, a right rear load transfer surface 5BR for transferring the load to the right rear connecting member 12R, a left front load transfer surface 5FL for transferring the load to the left front connecting member 11L, and a left rear load transfer surface 5BL for transferring the load to the left rear connecting member 12L.

[0129] The right front load transfer surface 5FR is provided in a portion of the car body main body 10A forward of the right axle 13R and to the right of the turning center axis C. The right rear load transfer surface 5BR of the car body 10 is provided in a portion of the car body main body 10A rear of the right axle 13R and to the right of the turning center axis C. The left front load transfer surface 5FL of the car body 10 is provided in a portion of the car body main body 10A forward of the left axle 13L and to the left of the turning center axis C. The left rear load transfer surface 5BL of the car body 10 is provided in a portion of the car body main body 10A rear of the left axle 13L and to the left of the turning center axis C.

[0130] Each of the multiple connecting members 11R, 12R, 11L, 12L has a load receiving surface for receiving the load from the car body 10. Specifically, the right front connecting member 11R has a right front load receiving surface 3FR facing the right front load transfer surface 5FR of the car body 10. The right rear connecting member 12R has a right rear load receiving surface 3BR facing the right rear load transfer surface 5BR of the car body 10. The left front connecting member 11L has a left front load receiving surface 3FL facing the left front load transfer surface 5FL of the car body 10. The left rear connecting member 12L has a left rear load receiving surface 3BL facing the left rear load transfer surface 5BL of the car body 10.

[0131] The right front load receiving surface 3FR of the right front connecting member 11R and the left front load receiving surface 3FL of the left front connecting member 11L are surfaces that can receive a front load from the carbody 10, which is a load that the carbody 10 receives from the upper rotating body 102 when a load is suspended from the upper rotating body 102 forward of the lower running body 101. The front load that the right front load receiving surface 3FR and the left front load receiving surface 3FL receive from the carbody 10 is a portion of the total load that the carbody 10 receives from the upper rotating body 102 when a load is suspended from the upper rotating body 102 forward of the lower running body 101.

[0132] The right rear load receiving surface 3BR of the right rear connecting member 12R and the left rear load receiving surface 3BL of the left rear connecting member 12L are surfaces that can receive a rear load from the car body 10, which is a load that the car body 10 receives from the upper rotating body 102 when a load is suspended from the upper rotating body 102 rearward of the lower running body 101. The rear load that the right rear load receiving surface 3BR and the left rear load receiving surface 3BL receive from the car body 10 is a portion of the total load that the car body 10 receives from the upper rotating body 102 when a load is suspended from the upper rotating body 102 rearward of the lower running body 101.

[0133] In this embodiment, the load receiving surfaces 3FR, 3BR, 3FL, 3BL of the multiple connecting members 11R, 12R, 11L, 12L and the load transfer surfaces 5FR, 5BR, 5FL, 5BL of the car body 10 are each composed of surfaces perpendicular to the left-right direction, but are not limited to this form.

[0134] Each of the multiple connecting members 11R, 12R, 11L, 12L has a load transfer surface for transferring the load received from the car body 10 to the crawler frame. Specifically, the right front connecting member 11R has a right front load transfer surface 4FR facing the right frame main body 20R of the right crawler frame 2R. The right rear connecting member 12R has a right rear load transfer surface 4BR facing the right frame main body 20R of the right crawler frame 2R. The left front connecting member 11L has a left front load transfer surface 4FL facing the left frame main body 20L of the left crawler frame 2L. The left rear connecting member 12L has a left rear load transfer surface 4BL facing the left frame main body 20L of the left crawler frame 2L.

[0135] The right front load transfer surface 4FR is a surface that can transfer the front load to the right crawler frame 2R, the left front load transfer surface 4FL is a surface that can transfer the front load to the left crawler frame 2L, the right rear load transfer surface 4BR is a surface that can transfer the rear load to the right crawler frame 2R, and the left rear load transfer surface 4BL is a surface that can transfer the rear load to the left crawler frame 2L.

[0136] The right axle 13R has a right middle load transfer surface 4MR for transferring the load received by the right axle 13R from the car body main body 10A to the right crawler frame 2R. The left axle 13L has a left middle load transfer surface 4ML for transferring the load received by the left axle 13L from the car body main body 10A to the left crawler frame 2L.

[0137] The right crawler frame 2R has a right front load receiving surface 6FR for receiving the load from the right front connecting member 11R, a right rear load receiving surface 6BR for receiving the load from the right rear connecting member 12R, and a right intermediate load receiving surface 6MR for receiving the load from the right axle 13R. The left crawler frame 2L has a left front load receiving surface 6FL for receiving the load from the left front connecting member 11L, a left rear load receiving surface 6BL for receiving the load from the left rear connecting member 12L, and a left intermediate load receiving surface 6ML for receiving the load from the left axle 13L.

[0138] Specific examples of the multiple load transfer surfaces of the car body 10 are as follows. That is, as shown in Fig. 9, the left rear load transfer surface 5BL of the car body 10 may be formed by a side surface (the left side surface in Fig. 9) of a wall portion W4 that is a part of the car body 10. Although not shown, the other load transfer surfaces 5FR, 5BR, 5FL may also be formed in the same manner as the left rear load transfer surface 5BL shown in Fig. 9.

[0139] Specific examples of the load receiving surfaces of each of the multiple connecting members 11R, 12R, 11L, 12L are as follows. That is, as shown in Fig. 9, for example, the left rear load receiving surface 3BL of the left rear connecting member 12L may be formed by a side surface (the right side surface in Fig. 9) of a wall portion W5 that is a part of the left rear connecting member 12L. Although not shown, the other load receiving surfaces 3FR, 3BR, 3FL may also be configured similarly to the left rear load receiving surface 3BL shown in Fig. 9.

[0140] Specific examples of the load transfer surfaces of the multiple connecting members 11R, 12R, 11L, and 12L are as follows. That is, as shown in FIG. 7, for example, the left rear load transfer surface 4BL of the left rear connecting member 12L may be provided on the crawler connection part 42L of the left rear connecting member 12L. This left rear load transfer surface 4BL may be formed by an inner circumferential surface that defines the pin insertion hole H11 of the crawler connection part 42L. In this case, the load that the left rear connecting member 12L receives from the car body 10 is transferred to the crawler connection part 42L via the car body connection part 32L and the connecting member main body 72L, and is transferred from the left rear load transfer surface 4BL formed by the inner circumferential surface that defines the pin insertion hole H11 to a pair of protruding pieces PL1 of the left rear connected part 62L of the left crawler frame 2L via the pin P11.

[0141] In this case, as shown in Fig. 7, the left rear load receiving surface 6BL of the left crawler frame 2L may be provided on each of a pair of protruding pieces PL1 of the left rear connected portion 62L. The left rear load receiving surface 6BL may be formed by the inner circumferential surface that defines each of the pin insertion holes H12 of the pair of protruding pieces PL1. The load is transmitted from the crawler connection portion 42L of the left rear connecting member 12L via the pin P11 to the left rear load receiving surface 6BL, and is further transmitted to the left frame main body 20L of the left crawler frame 2L.

[0142] Although not shown in the figures, the other load transfer surfaces 4FR, 4BR, 4FL may also be configured similarly to the left rear load transfer surface 4BL shown in Figure 7, and the other load receiving surfaces 6FR, 6BR, 6FL may also be configured similarly to the left rear load receiving surface 6BL shown in Figure 7.

[0143] Specific examples of the right intermediate load transfer surface 4MR of the right axle 13R and the left intermediate load transfer surface 4ML of the left axle 13L are as follows: That is, as shown in Fig. 11, for example, the left intermediate load transfer surface 4ML of the left axle 13L may be formed by a side surface (left side surface in Fig. 11) of a wall portion W6 that is a part of the left axle 13L.

[0144] In this case, as shown in FIG. 11, the left middle load receiving surface 6ML of the left crawler frame 2L may be formed by a side surface (the right side surface in FIG. 11) of a wall W7 that is part of the left crawler frame 2L.

[0145] Although not shown in the figures, the right intermediate load transfer surface 4MR of the right axle 13R may also be configured similarly to the left intermediate load transfer surface 4ML shown in Figure 11, and the right intermediate load receiving surface 6MR of the right crawler frame 2R may also be configured similarly to the left intermediate load receiving surface 6ML shown in Figure 11.

[0146] 3, the right front connecting member 11R has a shape such that a right front straight line LA, which is a straight line passing through a point A1 included in the right front load receiving surface 3FR of the right front connecting member 11R and a point A2 included in the right front load transfer surface 4FR, passes through the right front end roller 261. The left front connecting member 11L has a shape such that a left front straight line LC, which is a straight line passing through a point C1 included in the left front load receiving surface 3FL of the left front connecting member 11L and a point C2 included in the left front load transfer surface 4FL, passes through the left front end roller 261. In this embodiment, the right front straight line LA is a straight line that further passes through the turning central axis C, and the left front straight line LC is a straight line that further passes through the turning central axis C.

[0147] However, point A1 on the right front load receiving surface 3FR and point A2 on the right front load transfer surface 4FR for defining the right front straight line LA are not limited to the above-mentioned positions. Point A1 may be another point included in the right front load receiving surface 3FR that can receive a front load from the right front load transfer surface 5FR of the car body 10, and point A2 may be another point included in the right front load transfer surface 4FR that can transfer a front load to the right front load receiving surface 6FR of the right crawler frame 2R. Specifically, the right front straight line LA may be a straight line passing through the rearmost point of the right front load receiving surface 3FR and the frontmost point of the right front load transfer surface 4FR in the plan view shown in FIG. 3, for example.

[0148] Similarly, point C1 on the left front load receiving surface 3FL and point C2 on the left front load transfer surface 4FL for defining the left front straight line LC are not limited to the above-mentioned positions. Point C1 may be another point included in the left front load receiving surface 3FL that can receive a front load from the left front load transfer surface 5FL of the car body 10, and point C2 may be another point included in the left front load transfer surface 4FL that can transfer a front load to the left front load receiving surface 6FL of the left crawler frame 2L. Specifically, the left front straight line LC may be, for example, a straight line passing through the rearmost point of the left front load receiving surface 3FL and the frontmost point of the left front load transfer surface 4FL in the plan view shown in FIG. 3.

[0149] The right front connecting member 11R has a right front continuing portion CX that continues from the right front load receiving surface 3FR to the right front load transfer surface 4FR along the right front straight line LA in a plan view, and the left front connecting member 11L has a left front continuing portion CX that continues from the left front load receiving surface 3FL to the left front load transfer surface 4FL along the left front straight line LC in a plan view. Specifically, the right front continuing portion CX continues from the right front load receiving surface 3FR to the right front load transfer surface 4FR while overlapping with the right front straight line LA in a plan view, and the left front continuing portion CX continues from the left front load receiving surface 3FL to the left front load transfer surface 4FL while overlapping with the left front straight line LC in a plan view.

[0150] The right rear connecting member 12R has a shape such that, in the plan view shown in Fig. 3, a right rear straight line LB, which is a straight line passing through a point B1 included in the right rear load receiving surface 3BR of the right rear connecting member 12R and a point B2 included in the right rear load transfer surface 4BR, passes through the right rear end roller 262. The left rear connecting member 12L has a shape such that, in the plan view shown in Fig. 3, a left rear straight line LD, which is a straight line passing through a point D1 included in the left rear load receiving surface 3BL of the left rear connecting member 12L and a point D2 included in the left rear load transfer surface 4BL, passes through the left rear end roller 262. In this embodiment, the right rear straight line LB is a straight line that further passes through the turning central axis C, and the left rear straight line LD is a straight line that further passes through the turning central axis C.

[0151] However, point B1 on the right rear load receiving surface 3BR and point B2 on the right rear load transfer surface 4BR for defining the right rear straight line LB are not limited to the above-mentioned positions. Point B1 may be another point included in the right rear load receiving surface 3BR that can receive the rear load from the right rear load transfer surface 5BR of the car body 10, and point B2 may be another point included in the right rear load transfer surface 4BR that can transfer the rear load to the right rear load receiving surface 6BR of the right crawler frame 2R. Specifically, the right rear straight line LB may be a straight line passing through the frontmost point of the right rear load receiving surface 3BR and the rearmost point of the right rear load transfer surface 4BR in the plan view shown in FIG. 3, for example.

[0152] Similarly, point D1 on the left rear load receiving surface 3BL and point D2 on the left rear load transfer surface 4BL for defining the left rear straight line LD are not limited to the above-mentioned positions. Point D1 may be another point included in the left rear load receiving surface 3BL that can receive a rear load from the left rear load transfer surface 5BL of the car body 10, and point D2 may be another point included in the left rear load transfer surface 4BL that can transfer a rear load to the left rear load receiving surface 6BL of the left crawler frame 2L. Specifically, the left rear straight line LD may be, for example, a straight line passing through the frontmost point of the left rear load receiving surface 3BL and the rearmost point of the left rear load transfer surface 4BL in the plan view shown in FIG. 3.

[0153] The right rear connecting member 12R has a right rear continuing portion CX that continues from the right rear load receiving surface 3BR to the right rear load transfer surface 4BR along the right rear straight line LB in a plan view, and the left rear connecting member 12L has a left rear continuing portion CX that continues from the left rear load receiving surface 3BL to the left rear load transfer surface 4BL along the left rear straight line LD in a plan view. Specifically, the right rear continuing portion CX continues from the right rear load receiving surface 3BR to the right rear load transfer surface 4BR while overlapping with the right rear straight line LB in a plan view, and the left rear continuing portion CX continues from the left rear load receiving surface 3BL to the left rear load transfer surface 4BL while overlapping with the left rear straight line LD in a plan view.

[0154] As described above, in the lower traveling body 101 according to this embodiment, each of the multiple connecting members 11R, 12R, 11L, 12L is disposed in the extended position during crane operation, and is disposed in the close position during transportation of the mobile crane 100. This makes it possible to reduce deformation that occurs in the lower traveling body 101 when a load is suspended from the upper rotating body 102 in front of or behind the lower traveling body 101, to suppress an increase in dimensions of the parts that constitute the lower traveling body 101 during transportation of the mobile crane 100, and to suppress a decrease in the workability of disassembling and assembling the lower traveling body 101. Specifically, this is as follows.

[0155] During crane operation, the right front connecting member 11R arranged in the extended position can receive a front load, which is a load that the carbody 10 receives from the upper rotating body 102 when a load is suspended from the upper rotating body 102 forward of the lower running body 101, at the carbody connection part 31R of the right front connecting member 11R, and transmit it to the right frame main body 20R of the right crawler frame 2R via the crawler connection part 41R located diagonally forward to the right of the carbody connection part 31R. Similarly, the left front connecting member 11L can receive the front load at the carbody connection part 31L of the left front connecting member 11L, and transmit it to the left frame main body 20L of the left crawler frame 2L via the crawler connection part 41L located diagonally forward to the left of the carbody connection part 31L.

[0156] That is, the right front connecting member 11R and the left front connecting member 11L can support the car body 10 in front of the portion receiving the front load from the car body 10, so that the deflection deformation of the car body 10 caused by the front load can be effectively suppressed, that is, the rigidity of the car body 10 against the front load can be improved. Moreover, in this lower traveling body 101, compared to a conventional lower traveling body in which a load is transmitted to the left and right crawler frames via axles extending in parallel in the left-right direction, the portion where the front load is transmitted to the left and right crawler frames 2R, 2L can be brought closer to the front end of the frame body of each crawler frame. This makes it possible to reduce the deformation generated in the front part of the frame body of each crawler frame, that is, the portion between the portion where the front load is transmitted to the frame body of each crawler frame and the front end of the frame body of each crawler frame. Therefore, it is possible to reduce the deformation generated in the lower traveling body 101 when a load is suspended from the upper rotating body 102 in front of the lower traveling body 101. The reason why deformation occurring in the lower traveling body 101 when a load is suspended from the upper rotating body 102 behind the lower traveling body 101 can be reduced is the same as that described above.

[0157] In addition, in this lower traveling body 101, when the mobile crane 100 is transported, each of the multiple connecting members 11R, 12R, 11L, 12L is placed at the close position by rotating about the rotation center axis CA of the crawler connecting part with the car body connecting part detached from the connected part of the car body 10. The car body connecting part of each of the multiple connecting members 11R, 12R, 11L, 12L placed at the close position is located closer to the frame body of the corresponding crawler frame than the extended position. Therefore, it is possible to suppress an increase in the dimensions of the parts constituting the lower traveling body 101 when the mobile crane 100 is transported.

[0158] Moreover, in disassembling the lower traveling body 101, the worker does not need to remove both the car body connecting portion and the crawler connecting portion of each of the multiple connecting members 11R, 12R, 11L, 12L from the car body and the crawler frame. That is, the worker removes only the car body connecting portion of each of the multiple connecting members 11R, 12R, 11L, 12L from the connected portion of the car body 10, and displaces each of the multiple connecting members 11R, 12R, 11L, 12L from the protruding position to the approaching position by rotating the corresponding crawler connecting portion. This allows the worker to separate the car body 10 from the left and right crawler frames 2R, 2L. Therefore, the workability of the disassembly work is prevented from decreasing.

[0159] In addition, in the disassembly work, the crawler connection parts of the multiple connecting members 11R, 12R, 11L, and 12L are not removed from the connected parts of the crawler frame. Therefore, in the assembly work of the lower traveling body 101, the worker can omit the work of attaching the crawler connection parts of the multiple connecting members 11R, 12R, 11L, and 12L to the connected parts of the crawler frame. That is, the worker rotates each of the multiple connecting members 11R, 12R, 11L, and 12L at the crawler connection parts to displace each of the multiple connecting members 11R, 12R, 11L, and 12L from the close position to the extended position, and attaches the car body connection parts to the connected parts of the car body 10. This allows the worker to connect the car body 10 and the left and right crawler frames 2R and 2L with the multiple connecting members 11R, 12R, 11L, and 12L. Therefore, the deterioration of the workability of the assembly work is suppressed.

[0160] [Modification of the first embodiment] Fig. 13 is a plan view showing a lower running body 101 according to a modified example of the first embodiment. The lower running body 101 according to this modified example differs from the lower running body 101 shown in Fig. 3 in the orientation of the load transfer surfaces 5FR, 5BR, 5FL, 5BL of the car body 10 and the orientation of the load receiving surfaces 3FR, 3BR, 3FL, 3BL of the multiple connecting members 11R, 12R, 11L, 12L, but the other basic structures are the same as those of the lower running body 101 shown in Fig. 3. Specifically, it is as follows.

[0161] As shown in Fig. 13, the right front load transfer surface 5FR of the car body 10 faces diagonally forward to the right, and the right front load receiving surface 3FR of the right front connecting member 11R facing the right front load transfer surface 5FR faces diagonally backward to the left. The right rear load transfer surface 5BR of the car body 10 faces diagonally backward to the right, and the right rear load receiving surface 3BR of the right rear connecting member 12R facing the right rear load transfer surface 5BR faces diagonally forward to the left. The left front load transfer surface 5FL of the car body 10 faces diagonally forward to the left, and the left front load receiving surface 3FL of the left front connecting member 11L facing the left front load transfer surface 5FL faces diagonally backward to the right. The left rear load transfer surface 5BL of the car body 10 faces diagonally backward to the left, and the left rear load receiving surface 3BL of the left rear connecting member 12L facing the left rear load transfer surface 5BL faces diagonally forward to the right.

[0162] In this modification, the orientations of the right front load transfer surface 5FR and the right front load receiving surface 3FR can be made closer to the direction in which the right front connecting member 11R extends from the car body 10 to the right crawler frame 2R, i.e., the direction in which the front load is transferred to the right crawler frame 2R via the right front connecting member 11R, so that the right front load transfer surface 5FR and the right front load receiving surface 3FR can efficiently transfer the front load from the car body 10 to the right front connecting member 11R. Similarly, the orientations of the left front load transfer surface 5FL and the left front load receiving surface 3FL can be made closer to the direction in which the left front connecting member 11L extends from the car body 10 to the left crawler frame 2L, i.e., the direction in which the front load is transferred to the left crawler frame 2L via the left front connecting member 11L, so that the left front load transfer surface 5FL and the left front load receiving surface 3FL can efficiently transfer the front load from the car body 10 to the left front connecting member 11L. For the same reasons as described above, the right rear load transfer surface 5BR and the right rear load receiving surface 3BR, as well as the left rear load transfer surface 5BL and the left rear load receiving surface 3BL, can efficiently transfer the rear load from the car body 10 to the right rear connecting member 12R and the left rear connecting member 12L, respectively.

[0163] In this modification, it is more preferable that the right front load transfer surface 5FR and the right front load receiving surface 3FR are surfaces perpendicular to the right front straight line LA, the right rear load transfer surface 5BR and the right rear load receiving surface 3BR are surfaces perpendicular to the right rear straight line LB, the left front load transfer surface 5FL and the left front load receiving surface 3FL are surfaces perpendicular to the left front straight line LC, and the left rear load transfer surface 5BL and the left rear load receiving surface 3BL are surfaces perpendicular to the left rear straight line LD. In this case, the front load and the rear load are more efficiently transferred from the car body 10 to each of the multiple connecting members 11R, 12R, 11L, and 12L.

[0164] In addition, in the lower running body 101 of the modified example shown in Figure 13, similar to the lower running body 101 of the embodiment shown in Figure 3 etc., each of the multiple connecting members 11R, 12R, 11L, 12L is configured so as to be able to be displaced between the extended state shown by the solid line in Figure 13 and the approach position shown by the dotted line in Figure 13.

[0165] [Structure of the lower running body according to the second embodiment] Fig. 14 is a plan view showing the lower running body 101 according to the second embodiment. Fig. 15 is a plan view showing the car body 10 and multiple connecting members 11R, 12R, 11L, 12L of the lower running body 101 according to the second embodiment. The lower running body 101 according to the second embodiment differs from the lower running body 101 according to the first embodiment mainly in the following three differences (1) and (2).

[0166] That is, (1) in this second embodiment, in the multiple connecting members 11R, 12R, 11L, 12L, the car body connection portions 31R, 32R, 31L, 32L are pivotal connection portions, the crawler connection portions 41R, 42R, 41L, 42L are detachable connection portions, the car body 10 is a pivoted member, and each of the right crawler frame 2R and the left crawler frame 2L is a detachable member.

[0167] (2) In addition, in this second embodiment, each of the multiple connecting members 11R, 12R, 11L, and 12L is configured to be positioned at the extended position and function as a lift member (translifter) for lifting the car body 10 during assembly work to assemble the lower running body 101 and disassembly work to disassemble the lower running body 101.

[0168] In addition, the configuration of the lower running body 101 of the second embodiment is similar to that of the lower running body 101 of the first embodiment other than the two differences (1) and (2) described above, so the same symbols as in the first embodiment are used and detailed descriptions are omitted.

[0169] First, the difference (1) will be explained.

[0170] In the lower traveling body 101 according to the second embodiment, each of the multiple connecting members 11R, 12R, 11L, 12L is configured to be displaceable between an extended state in which the connecting members are disposed at the extended position shown in Fig. 14 and a close state in which the connecting members are disposed at the close position shown in Fig. 15 by rotating around a rotation center axis CB at the car body connection portion. Specifically, the configuration is as follows.

[0171] The car body connection part 31R of the right front coupling member 11R is rotatably connected to the right front connected part 51R of the car body 10, and the crawler connection part 41R of the right front coupling member 11R is detachably connected to the right front connected part 61R of the right crawler frame 2R. The right front coupling member 11R is configured such that the crawler connection part 41R can be disposed at a close position closer to the car body 10 (rotatable member) than the extended position by rotating at the car body connection part 31R (rotatable connection part) in a state where the crawler connection part 41R (detachable connection part) is detached from the right crawler frame 2R (detachable member).

[0172] The car body connection part 32R of the right rear coupling member 12R is rotatably connected to the right rear connected part 52R of the car body 10, and the crawler connection part 42R of the right rear coupling member 12R is detachably connected to the right rear connected part 62R of the right crawler frame 2R. The right rear coupling member 12R is configured such that the crawler connection part 42R can be disposed at a close position closer to the car body 10 (rotatable member) than the extended position by rotating at the car body connection part 32R (rotatable connection part) in a state where the crawler connection part 42R (detachable connection part) is detached from the right crawler frame 2R (detachable member).

[0173] The car body connection part 31L of the left front coupling member 11L is rotatably connected to the left front connected part 51L of the car body 10, and the crawler connection part 41L of the left front coupling member 11L is detachably connected to the left front connected part 61L of the left crawler frame 2L. The left front coupling member 11L is configured such that the crawler connection part 41L can be disposed at a close position closer to the car body 10 (rotatable member) than the extended position by rotating at the car body connection part 31L (rotatable connection part) in a state where the crawler connection part 41L (detachable connection part) is detached from the left crawler frame 2L (detachable member).

[0174] The car body connection part 32L of the left rear coupling member 12L is rotatably connected to the left rear connected part 52L of the car body 10, and the crawler connection part 42L of the left rear coupling member 12L is detachably connected to the left rear connected part 62L of the left crawler frame 2L. The left rear coupling member 12L is configured such that the crawler connection part 42L can be disposed at a close position closer to the car body 10 (rotatable member) than the extended position by rotating at the car body connection part 32L (rotatable connection part) in a state where the crawler connection part 42L (detachable connection part) is detached from the left crawler frame 2L (detachable member).

[0175] Fig. 16 is a front view showing the car body 10, the right front connecting member 11R, and the left front connecting member 11L of the lower running body 101 according to the second embodiment. Fig. 17 is a left side view showing the car body 10, the left front connecting member 11L, and the left rear connecting member 12L of the lower running body 101 according to the second embodiment.

[0176] The connection structure between each of the car body connecting parts 31R, 32R, 31L, 32L of the multiple connecting members 11R, 12R, 11L, 12L and the car body 10 can be, for example, the same structure as the connection structure described with reference to Figures 7 and 8. That is, each of the car body connecting parts of the multiple connecting members 11R, 12R, 11L, 12L according to the second embodiment shown in Figures 14, 16, and 17 may have a structure similar to the crawler connecting part 42L according to the first embodiment shown in Figures 7 and 8, and each of the connected parts 51R, 52R, 51L, 52L of the car body 10 according to the second embodiment may have a structure similar to the connected part 62L according to the first embodiment shown in Figures 7 and 8. Specifically, as shown in Figures 16 and 17, each of the car body connection portions 31R, 32R, 31L, 32L of the multiple connecting members 11R, 12R, 11L, 12L in the second embodiment has a pin insertion hole H11 that penetrates the car body connection portion in the vertical direction, and each of the connected portions 51R, 52R, 51L, 52L of the car body 10 has a pair of protruding pieces PL1, and each of the pair of protruding pieces PL1 may have a pin insertion hole H12 at a position corresponding to the pin insertion hole H11 of the car body connection portion.

[0177] The connection structure between the crawler connection parts 41R, 42R of the right front connecting member 11R and the right rear connecting member 12R and the right crawler frame 2R, and the connection structure between the crawler connection parts 41L, 42L of the left front connecting member 11L and the left rear connecting member 12L and the left crawler frame 2L may be the same as the connection structure described with reference to Fig. 11 and Fig. 12. That is, the crawler connection parts of the multiple connecting members 11R, 12R, 11L, 12L according to the second embodiment shown in Fig. 14, Fig. 16, and Fig. 17 may have the same structure as the left intermediate connection part 43L according to the first embodiment shown in Fig. 11 and Fig. 12, and the connected parts 61R, 62R, 61L, 62L of the left and right crawler frames 2R, 2L according to the second embodiment may have the same structure as the connected part 63L according to the first embodiment shown in Fig. 11 and Fig. 12. Specifically, as shown in Figures 16 and 17, each of the crawler connection portions 41R, 42R, 41L, 42L of the multiple connecting members 11R, 12R, 11L, 12L according to the second embodiment has a protruding piece PL4, and the protruding piece PL4 may have a pin insertion hole H41 and an engaged portion E4. Although not shown, each of the connected portions 61R, 62R, 61L, 62L of the left and right crawler frames 2R, 2L according to the second embodiment may have a pair of protruding pieces PL5 as shown in Figures 11 and 12, and a rod-shaped engaging portion E3 that is disposed so as to straddle these protruding pieces PL5 and is supported by these protruding pieces PL5.

[0178] Next, the difference (2) will be explained.

[0179] Fig. 18 is a front view showing the car body 10, the right front connecting member 11R, and the left front connecting member 11L of the lower running body 101 according to the second embodiment. Fig. 19 is a left side view showing the car body 10, the left front connecting member 11L, and the left rear connecting member 12L of the lower running body 101 according to the second embodiment. Figs. 18 and 19 show the state when each of the multiple connecting members 11R, 12R, 11L, and 12L is placed at the protruding position and used as a lift member (translifter) for lifting the car body 10 during the assembly and disassembly of the lower running body 101. Specifically, it is as follows.

[0180] 18 and 19, the right front connecting member 11R includes a car body connecting portion 31R, a crawler connecting portion 41R, a connecting member main body 71R connecting these connecting portions 31R, 41R, and a leg portion 81 supported by the connecting member main body 71R. Similarly, the left front connecting member 11L includes a car body connecting portion 31L, a crawler connecting portion 41L, a connecting member main body 71L connecting these connecting portions 31L, 41L, and a leg portion 81 supported by the connecting member main body 71L, and the left rear connecting member 12L includes a car body connecting portion 32L, a crawler connecting portion 42L, a connecting member main body 72L connecting these connecting portions 32L, 42L, and a leg portion 81 supported by the connecting member main body 72L. Although detailed illustration is omitted, the right front connecting member 11R includes a car body connection portion 31R, a crawler connection portion 41R, a connecting member main body 71R connecting these connection portions 31R, 41R, and a leg portion 81 supported by the connecting member main body 71R.

[0181] Each leg 81 is configured to be displaceable between a remote position away from the ground as shown in Figures 16 and 17, and a contact position extending downward from the connecting member main body 71R and contacting the ground G as shown in Figures 18 and 19. Each leg 81 is configured by a hydraulic cylinder including a cylinder main body 82 fixed to the corresponding connecting member main body and extending in the vertical direction, a rod 83 that is slidable in the vertical direction relative to the cylinder main body 82, and a lower end portion 84 that is detachably connected to a lower end 83E of the rod 83 (see Figures 16 and 17).

[0182] The lower end 84 of the leg 81 has a lower surface with an outer diameter larger than that of the rod 83, and is provided to increase the contact area with the ground G. The lower end 84 is attached to the lower end 83E of the rod 83 when each of the multiple connecting members 11R, 12R, 11L, and 12L is used as a lifting member (translifter) in the assembly and disassembly work of the lower running body 101 as shown in Figures 18 and 19, and is detached from the lower end 83E of the rod 83 as shown in Figures 16 and 17 when each of the multiple connecting members 11R, 12R, 11L, and 12L is used as a load transmitting member in crane work and when the mobile crane 100 is transported.

[0183] In the second embodiment, the car body 10 has a plurality of right axles that connect the car body main body 10A and the right crawler frame 2R rear of the right front connecting member 11R and forward of the right rear connecting member 12R, and a plurality of left axles that connect the car body main body 10A and the left crawler frame 2L rear of the left front connecting member 11L and forward of the left rear connecting member 12L.

[0184] Specifically, as shown in Figures 14 and 15, the car body 10 has two right axles 13R and two left axles 13L. One of the two right axles 13R extends from the car body main body 10A to the right crawler frame 2R on the front side of the turning center axis C. The other of the two right axles 13R extends from the car body main body 10A to the right crawler frame 2R on the rear side of the turning center axis C. One of the two left axles 13L extends from the car body main body 10A to the left crawler frame 2L on the front side of the turning center axis C. The other of the two left axles 13L extends from the car body main body 10A to the left crawler frame 2L on the rear side of the turning center axis C.

[0185] The right crawler frame 2R has two right intermediate connected parts 63R, and the left crawler frame 2L has two left intermediate connected parts 63L.

[0186] Each of the two right axles 13R has a right intermediate connection part 43R that is detachably connected to the corresponding one of the two right intermediate connection parts 63R of the right crawler frame 2R, and an axle body 73R that connects the right intermediate connection part 43R to the car body main body 10A. The right intermediate connection part 43R constitutes the tip part of the right axle 13R. The axle body 73R is a part that has a shape that extends to the right side from the car body main body 10A, and occupies the majority of the right axle 13R.

[0187] Each of the two left axles 13L has a left intermediate connection part 43L that is detachably connected to a corresponding one of the two left intermediate connection parts 63L of the left crawler frame 2L, and an axle body 73L that connects the left intermediate connection part 43L to the car body main body 10A. The left intermediate connection part 43L forms the tip part of the left axle 13L. The axle body 73L is a part that has a shape that extends leftward from the car body main body 10A, and occupies the majority of the left axle 13L.

[0188] In the second embodiment, the connection structure between the right intermediate connection portion 43R of each right axle 13R and the right intermediate connected portion 63R of the right crawler frame 2R, and the connection structure between the left intermediate connection portion 43L of each left axle 13L and the left intermediate connected portion 63L of the left crawler frame 2L are similar to the connection structures according to the first embodiment described with reference to Figures 11 and 12, and therefore detailed description thereof will be omitted.

[0189] In the lower running body 101 of the second embodiment, the car body 10 has two right intermediate connection parts 43R and two left intermediate connection parts 43L, but may have only a single right intermediate connection part 43R and a single left intermediate connection part 43L.

[0190] The lower running body 101 according to the second embodiment further includes a plurality of fixing members P51 for fixing each of the plurality of connecting members 11R, 12R, 11L, 12L to the extended position and the approaching position, respectively. Fig. 20 is an enlarged plan view of the car body 10 and the left rear connecting member 12L of the lower running body 101 according to the second embodiment. Fig. 20 shows only the structure for fixing the left rear connecting member 12L to the extended position and the approaching position, respectively, but each of the other connecting members 11R, 12R, 11L has a similar structure.

[0191] In the second embodiment, each fixing member P51 has both a function as a protruding position fixing member and a function as a close position fixing member, similar to the fixing member P21 in the first embodiment. The protruding position fixing member is a member for temporarily fixing the connecting member to the protruding position, and the close position fixing member is a member for temporarily fixing the connecting member to the close position. However, the protruding position fixing member and the close position fixing member may be formed of different members.

[0192] In the second embodiment, the fixing member P21 is a pin. With the left rear connecting member 12L in the extended position shown by the solid line in Fig. 20, the fixing member P51 is inserted into the pin insertion hole H51 provided in the car body 10 and the pin insertion hole H52 provided in the left rear connecting member 12L. This restricts the left rear connecting member 12L from rotating relative to the car body 10, and fixes the left rear connecting member 12L to the extended position. When the fixing member P51 is removed from the pin insertion holes H51 and H52, the left rear connecting member 12L becomes able to rotate relative to the car body 10.

[0193] With the left rear connecting member 12L disposed at the approach position indicated by the two-dot chain line in Fig. 20, the fixing member P51 is inserted into the pin insertion hole H51 of the car body 10 and the pin insertion hole H53 provided in the left rear connecting member 12L. This restricts the left rear connecting member 12L from rotating relative to the car body 10, and fixes the left rear connecting member 12L at the approach position. When the fixing member P51 is removed from the pin insertion holes H51 and H53, the left rear connecting member 12L becomes capable of rotating relative to the car body 10. The two pin insertion holes H52 and H53 are provided on the same arc centered on the rotation central axis C2 in a plan view.

[0194] [Modification of the second embodiment] Fig. 21 is a cross-sectional view showing a lower traveling body 101 according to a modified example of the second embodiment. Fig. 22 is a perspective view showing a car body, a connecting member, and a crawler frame of a lower traveling body according to a modified example of the second embodiment. The cross-sectional view of Fig. 21 shows a cross section of the lower traveling body 101 cut by a vertical plane that includes the turning center axis C and is parallel to the front-rear direction.

[0195] In the modified example shown in Figures 21 and 22, the connection structure in which the right crawler connection parts 41R, 42R of the connecting members 11R, 12R are connected to the connected parts of the crawler frame 2R, and the connection structure in which the crawler connection parts 41L, 42L of the connecting members 11L, 12L are connected to the connected parts of the left crawler frame 2L are different from the connection structures in the second embodiment shown in Figures 16 and 17. Specifically, this is as follows.

[0196] 16 and 17 has a structure in which the crawler connection parts of each connecting member are connected to the connected parts of the crawler frame by pins, but in the modified example shown in Figures 21 and 22, the crawler connection parts of each connecting member are connected to the connected parts of the crawler frame without using pins. Note that the connection structures of the four connecting members 11R, 12R, 11L, 12L are the same, so Figures 21 and 22 show in schematic diagrams only the structure for connecting the crawler connection part 42L of the left rear connecting member 12L to the connected part 21 of the left crawler frame 2L.

[0197] In the modified example shown in FIG. 21 and FIG. 22, for example, the crawler connection part 42L of the left rear connecting member 12L and the connected part 21 of the left crawler frame 2L may be connected by fitting one of them into the other. Specifically, for example, the connected part 21 of the left crawler frame 2L may have a recess corresponding to the shape of the crawler connection part 42L of the left rear connecting member 12L, and the crawler connection part 42L may be fitted into this recess. Also, a structure may be such that a float (lower end of the leg) attached to the lower end of the rod of the leg 81 of the left rear connecting member 12L fits into a recess formed in the connected part 21 of the left crawler frame 2L. Also, a structure may be such that a lower end of the rod from which the float has been removed (for example, a lower end having a spherical surface) fits into a recess formed in the connected part 21 of the left crawler frame 2L. However, the structure in which the crawler connection part of each connecting member is connected to the connected part of the crawler frame without using a pin is not limited to the above specific example.

[0198] The present invention is not limited to the above-described embodiment. The present invention includes, for example, the following aspects.

[0199] (A) Rotating and detachable connections In the first embodiment, all four car body connection parts of the four connecting members are detachable connection parts, and all four crawler connection parts of the four connecting members are pivotal connection parts, and in the second embodiment, all four car body connection parts of the four connecting members are pivotal connection parts, and all four crawler connection parts of the four connecting members are detachable connection parts, but the present invention is not limited to these forms. For example, the four detachable connection parts may be a mixture of car body connection parts and crawler connection parts, and the four pivotal connection parts may be a mixture of car body connection parts and crawler connection parts.

[0200] (B) Right front line, right rear line, left front line and left rear line In the first and second embodiments, the multiple connecting members are configured such that, in a plan view, the right front straight line LA passes through the right front end roller 261, the right rear straight line LB passes through the right rear end roller 262, the left front straight line LC passes through the left front end roller 261, and the left rear straight line LD passes through the left rear end roller 262, but are not limited to such an aspect. The right front straight line LA may pass in front of or behind the right front end roller 261, the right rear straight line LB may pass behind or in front of the right rear end roller 262, the left front straight line LC may pass in front of or behind the left front end roller 261, and the left rear straight line LD may pass behind or in front of the left rear end roller 262.

[0201] In the above embodiment, the right front straight line LA is a straight line that connects the central position of the right front end roller 261 in the width direction (left-right direction) on the rotation central axis of the right front end roller 261 and the turning central axis C in a plan view, and the right rear straight line LB, the left front straight line LC, and the left rear straight line LD are similarly defined, but are not limited to such an embodiment. The right front straight line LA may be, for example, a straight line that connects the turning central axis C and any part of the right front end roller 261 that has been selected in advance in a plan view. The any part may be, for example, the rearmost and rightmost part of the right front end roller 261 in a plan view. Similarly, the right rear straight line LB may be, in a planar view, a straight line connecting the pivot axis C and any pre-selected portion of the right rear end roller 262, the left front straight line LC may be, for example, in a planar view, a straight line connecting the pivot axis C and any pre-selected portion of the left front end roller 261, and the left rear straight line LD may be, in a planar view, a straight line connecting the pivot axis C and any pre-selected portion of the left rear end roller 262.

[0202] (C) Right and left axles The car body 10 in the first embodiment has a right axle 13R and a left axle 13L, but if the multiple connecting members 11R, 12R, 11L, and 12L have the rigidity to support the car body 10, the right axle 13R and the left axle 13L may be omitted.

[0203] Similarly, the car body 10 of the second embodiment has a pair of right axles 13R and a pair of left axles 13L, but if the multiple connecting members 11R, 12R, 11L, 12L have the rigidity to support the car body 10, at least one of the pair of right axles 13R and at least one of the pair of left axles 13L may be omitted.

[0204] (D) Orientation of the load suspended from the upper rotating body The present invention can suppress deformation of each crawler frame when a load is suspended from the upper rotating body with the load positioned in front of or behind the lower running body, but does not exclude the application of the present invention to a case where the load is suspended from the upper rotating body with the load positioned to the side of the lower running body.

[0205] (E) Crane specifications The crane according to the embodiment shown in Fig. 1 does not include a jib and a strut, but the specifications of the crane are not limited to those shown in Fig. 1. The crane according to the present disclosure may be a luffing crane including a jib, a front strut, and a rear strut, or may be a fixed jib crane including a jib and one strut. In addition, the crane according to the present disclosure may be a crane including a mast instead of a gantry (e.g., a large crane). [Explanation of symbols]

[0206] 2L: Left crawler frame 2R: Right crawler frame 10: Car body 11L: Left front connecting member 11R: Right front connecting member 12L: Left rear connecting member 12R: Right rear connecting member 13L: Left axle 13R: Right axle 26: Right roller, left roller 261: Left front roller, right front roller 262: Right rear roller, left rear roller 100: Mobile crane 101: Lower running body 102: Upper rotating body C: Rotation center axis C1: Rotation center axis CX: Right front continuous part, left front continuous part LA: Right front straight line LB:Right rear straight line LC: Front left straight line LD: Left rear straight line

Claims

1. A lower running body of a mobile crane, a car body that supports an upper rotating body of the mobile crane so as to be rotatable around a central axis of rotation; a right crawler frame extending in a front-rear direction on a right side of the car body; a left crawler frame extending in the front-rear direction on a left side of the car body; A plurality of connecting members, The plurality of connecting members include a right front connecting member having a car body connection portion connected to the car body and a crawler connection portion connected to the right crawler frame, the crawler connection portion connecting the car body and the right crawler frame at a protruding position located diagonally forward and to the right of the car body connection portion; a right rear connecting member having a car body connection portion connected to the car body and a crawler connection portion connected to the right crawler frame, the crawler connection portion of the right rear connecting member connecting the car body and the right crawler frame at a protruding position located diagonally rear to the right of the car body connection portion of the right rear connecting member; a left front connecting member having a car body connection portion connected to the car body and a crawler connection portion connected to the left crawler frame, the crawler connection portion of the left front connecting member connecting the car body and the left crawler frame at a protruding position located diagonally forward and to the left of the car body connection portion of the left front connecting member; a left rear connecting member having a car body connection portion connected to the car body and a crawler connection portion connected to the left crawler frame, wherein the crawler connection portion of the left rear connecting member connects the car body and the left crawler frame at a protruding position located diagonally left rear of the car body connection portion of the left rear connecting member, In each of the plurality of coupling members, the crawler connection portion is rotatably connected to a rotated member which is a member of the right crawler frame or the left crawler frame to which the crawler connection portion is connected, and the carbody connection portion is detachably connected to the carbody; A lower running body of a mobile crane, wherein each of the multiple connecting members is configured so that, when the carbody connection portion is detached from the carbody, it can be rotated at the crawler connection portion so that the carbody connection portion can be positioned at an approaching position that is closer to the rotated member than the extended position.

2. A lower running body of a mobile crane, a car body that supports an upper rotating body of the mobile crane so as to be rotatable around a central axis of rotation; a right crawler frame extending in a front-rear direction on a right side of the car body; a left crawler frame extending in the front-rear direction on a left side of the car body; A plurality of connecting members, The plurality of connecting members include a right front connecting member having a car body connection portion connected to the car body and a crawler connection portion connected to the right crawler frame, the crawler connection portion connecting the car body and the right crawler frame at a protruding position located diagonally forward and to the right of the car body connection portion; a right rear connecting member having a car body connection portion connected to the car body and a crawler connection portion connected to the right crawler frame, the crawler connection portion of the right rear connecting member connecting the car body and the right crawler frame at a protruding position located diagonally rear to the right of the car body connection portion of the right rear connecting member; a left front connecting member having a car body connection portion connected to the car body and a crawler connection portion connected to the left crawler frame, the crawler connection portion of the left front connecting member connecting the car body and the left crawler frame at a protruding position located diagonally forward and to the left of the car body connection portion of the left front connecting member; a left rear connecting member having a car body connection portion connected to the car body and a crawler connection portion connected to the left crawler frame, wherein the crawler connection portion of the left rear connecting member connects the car body and the left crawler frame at a protruding position located diagonally left rear of the car body connection portion of the left rear connecting member, In each of the plurality of coupling members, one of the car body connection portion and the crawler connection portion is a pivotal connection portion and the other is a detachable connection portion, the pivotal connection portion is pivotally connected to a pivoted member which is a member among the car body, the right crawler frame, and the left crawler frame to which the pivotal connection portion is connected, and the detachable connection portion is detachably connected to a detachable member which is a member among the car body, the right crawler frame, and the left crawler frame to which the detachable connection portion is connected, each of the plurality of connecting members is configured such that, when the detachable connection portion is detached from the detachable member, the detachable connection portion can be rotated at the pivot connection portion to be disposed at a close position closer to the rotatable member than the extended position; A lower running body of a mobile crane, wherein at least one of the multiple connecting members is configured to be positioned in the extended position and used as a lifting member for lifting the car body during at least one of an assembly operation for assembling the lower running body and a disassembly operation for disassembling the lower running body.

3. A lower traveling body of the mobile crane according to claim 2, The at least one connecting member is A connecting member main body that connects the car body connecting portion and the crawler connecting portion; A leg portion supported by the connecting member body, The leg portion is configured so as to be displaceable between a remote position away from the ground and a contact position in which the leg portion extends downward from the connecting member body and contacts the ground.

4. A lower traveling body of a mobile crane according to any one of claims 1 to 3, The undercarriage of the mobile crane further comprises a plurality of extension position fixing members for fixing the plurality of connecting members to the extension positions, respectively.

5. A lower traveling body of a mobile crane according to any one of claims 1 to 4, The undercarriage of the mobile crane further comprises a plurality of close position fixing members for fixing the plurality of connecting members at the close positions, respectively.

6. A lower traveling body of a mobile crane according to any one of claims 1 to 5, The car body is at least one right intermediate connection portion connected to the right crawler frame rearward of the right front connecting member and forward of the right rear connecting member; at least one left intermediate connection portion connected to the left crawler frame rearward of the left front connecting member and forward of the left rear connecting member.

7. A lower traveling body of a mobile crane according to any one of claims 1 to 6, a pair of right wheels rotatably supported on front and rear ends of the right crawler frame; a pair of left wheels rotatably supported on front and rear ends of the left crawler frame; a plurality of right rollers disposed at intervals in the front-rear direction between the pair of right wheels and rotatably supported on a lower portion of the right crawler frame, the plurality of right rollers including a right front end roller located at the forefront and a right rear end roller located at the rearmost; a plurality of left rollers disposed at intervals in the front-rear direction between the pair of left wheels and rotatably supported on a lower portion of the left crawler frame, the plurality of left rollers including a left front end roller located at the frontmost position and a left rear end roller located at the rearmost position, the right front connecting member has a right front load receiving surface facing the car body and a right front load transmitting surface facing the right crawler frame, the left front connecting member has a left front load receiving surface facing the car body and a left front load transmitting surface facing the left crawler frame, each of the right front load receiving surface of the right front connecting member and the left front load receiving surface of the left front connecting member is a surface that can receive, from the car body, a front load that is a load that the car body receives from the upper rotating body when a load is suspended from the upper rotating body forward of the lower running body, the right front load transfer surface is a surface that can transfer the front load to the right crawler frame, and the left front load transfer surface is a surface that can transfer the front load to the left crawler frame, the right front connecting member is configured such that a right front straight line, which is a straight line passing through any point included in the right front load receiving surface and any point included in the right front load transfer surface in a plan view, passes through the right front end roller or a side forward of the right front end roller, The left front connecting member is a lower running body of a mobile crane, and is configured so that a left front straight line, which is a straight line passing through any point included in the left front load receiving surface and any point included in the left front load transfer surface in a planar view, passes through the left front end roller or forward of the left front end roller.

8. A lower body of a mobile crane according to claim 7, A lower running body of a mobile crane, wherein the right front straight line is a straight line passing through the right front end roller in a plan view, and the left front straight line is a straight line passing through the left front end roller in a plan view.

9. The undercarriage of the mobile crane according to claim 8, A lower running body of a mobile crane, wherein the right front straight line is a straight line that further passes through the central axis of rotation in a plan view, and the left front straight line is a straight line that further passes through the central axis of rotation in a plan view.

10. A lower traveling body of a mobile crane according to any one of claims 7 to 9, the right front connecting member has a right front continuing portion that continues from the right front load receiving surface to the right front load transmitting surface along the right front straight line in a plan view, The left front connecting member has a left front continuing portion that continues from the left front load receiving surface to the left front load transfer surface along the left front straight line in a plan view, the lower running body of a mobile crane.

11. A lower traveling body of a mobile crane according to any one of claims 7 to 10, the right rear connecting member has a right rear load receiving surface facing the car body and a right rear load transmitting surface facing the right crawler frame, the left rear connecting member has a left rear load receiving surface facing the car body and a left rear load transmitting surface facing the left crawler frame, each of the right rear load receiving surface of the right rear connecting member and the left rear load receiving surface of the left rear connecting member is a surface that can receive a rear load from the car body, which is a load that the car body receives from the upper rotating body when a load is suspended from the upper rotating body rearward of the lower running body, the right rear load transfer surface is a surface that can transfer the rear load to the right crawler frame, and the left rear load transfer surface is a surface that can transfer the rear load to the left crawler frame, the right rear connecting member is configured such that a right rear straight line, which is a straight line passing through any point included in the right rear load receiving surface and any point included in the right rear load transfer surface in a plan view, passes through the right rear end roller or a side rearward of the right rear end roller, The left rear connecting member is a lower running body of a mobile crane, configured so that a left rear straight line, which is a straight line passing through any point included in the left rear load receiving surface and any point included in the left rear load transfer surface in a planar view, passes through the left rear end roller or rear of the left rear end roller.

12. The undercarriage of the mobile crane according to claim 11, A lower running body of a mobile crane, wherein the right rear straight line is a straight line passing through the right rear end roller in a plan view, and the left rear straight line is a straight line passing through the left rear end roller in a plan view.

13. 13. The undercarriage of the mobile crane according to claim 12, A lower running body of a mobile crane, wherein the right rear straight line is a straight line that further passes through the central axis of rotation in a plan view, and the left rear straight line is a straight line that further passes through the central axis of rotation in a plan view.

14. A lower traveling body of a mobile crane according to any one of claims 11 to 13, the right rear connecting member has a right rear continuing portion that continues from the right rear load receiving surface to the right rear load transmitting surface along the right rear straight line in a plan view, The left rear connecting member has a left rear continuing portion that continues from the left rear load receiving surface to the left rear load transfer surface along the left rear straight line in a plan view, the lower running body of a mobile crane.

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