Work Machine

Abstract

To provide a work machine that can be improved in work efficiency.SOLUTION: A work machine comprises: a plurality of booms that are expanded and contracted by power of an actuator; a first pin having a penetration-hole penetrating in an axial direction, which is moved by a spring to connect the booms to the actuator and is moved by power of a motor to release the connection; and a trunnion having a support part that supports the first pin movably and can be screwed with a screw member for manual operation inserted through the penetration hole from outside of the booms, where when the screw member for manual operation rotates with the screw member for manual operation screwed with the support part, the first pin moves together with the screw member for manual operation to release the connection.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a work machine equipped with a telescopic boom. [Background technology]

[0002] Patent Document 1 discloses a mobile crane equipped with a telescopic boom in which multiple booms are nested one inside the other, and a hydraulic actuator (telescopic cylinder) that extends the telescopic boom.

[0003] Adjacent booms are connected to each other by a connecting pin. A boom that is released from the connection by the connecting pin (hereinafter referred to as a movable boom) becomes movable in the telescopic direction relative to the other boom.

[0004] In addition, the actuator is connected to the movable boom via a connecting pin. When the actuator moves in the extension / retraction direction in this state, the movable boom moves together with the actuator, and the telescopic boom extends or retracts. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-96928 A Summary of the Invention [Problem to be solved by the invention]

[0006] In a crane such as that described above, if the mechanism connecting the actuator and the boom breaks down, it may become impossible to release the connection between the actuator and the boom, making it impossible to retract the telescopic boom.

[0007] An object of the present invention is to provide a work machine equipped with a mechanism that allows the connection between an actuator and a boom to be manually released. [Means for solving the problem]

[0008] One aspect of the working machine according to the present invention is A telescopic cylinder; Telescopic Cylinder A plurality of booms that are extended and retracted by the power of It has a through hole that runs through in the axial direction, and moves with a spring to become a boom. Telescopic Cylinder a first pin that connects the first and second electrodes to each other and moves by the power of a motor to release the connection; Provided on the telescopic cylinder, a trunnion that movably supports the first pin and has a support portion that can be screwed into a manually operated screw member that is inserted into the through hole from the outside of the boom, When the manually operable screw member is rotated in a state in which the manually operable screw member and the support portion are screwed together, the first pin moves together with the manually operable screw member, and the above-mentioned connection is released. Effect of the Invention

[0009] According to the present invention, a work machine equipped with a mechanism for manually releasing the connection between the actuator and the boom can be provided. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a mobile crane according to an embodiment. [Diagram 2] 2A to 2E are schematic diagrams for explaining the structure and telescopic operation of a telescopic boom. [Diagram 3] FIG. 3 is a schematic diagram for explaining the structure of the telescopic boom. [Figure 4] FIG. 4 is a cross-sectional view of the pin moving mechanism with the cylinder coupling mechanism in the expanded state. [Diagram 5] FIG. 5 is a cross-sectional view of the pin moving mechanism when the cylinder connecting mechanism is in a contracted state. [Figure 6A] FIG. 6A is a schematic diagram for explaining the operation of the cylinder connecting mechanism. [Figure 6B] FIG. 6B is a schematic diagram for explaining the operation of the cylinder connecting mechanism. [Figure 6C]FIG. 6C is a schematic diagram for explaining the operation of the cylinder connecting mechanism. [Figure 7A] FIG. 7A is a schematic diagram for explaining the operation of the boom connection mechanism. [Figure 7B] FIG. 7B is a schematic diagram for explaining the operation of the boom connection mechanism. [Figure 7C] FIG. 7C is a schematic diagram for explaining the operation of the boom connection mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. Note that a crane according to the embodiment described below is an example of a working machine according to the present invention, and the present invention is not limited to the embodiment described below.

[0012] [Embodiment] An overview of a mobile crane 1 according to this embodiment will be described with reference to Figs. 1 and 2A to 2E.

[0013] Examples of the mobile crane include a rough terrain crane, an all-terrain crane, a truck crane, and a loaded truck crane. However, the working machine is not limited to a mobile crane, and may be another working machine (e.g., an aerial work vehicle) equipped with a telescopic boom.

[0014] The mobile crane 1 has a telescopic boom 14 and an actuator 2. The telescopic boom 14 has a plurality of booms combined so as to be telescopic. Adjacent booms are connected to each other by boom connecting pins (boom connecting pins 144a, 144b).

[0015] When extending or retracting the telescopic boom 14, the actuator 2 moves the boom in the extension / retraction direction. At this time, the actuator 2 connects to the boom to be moved via the cylinder connecting pins 454A and 454B, and releases the connection between the boom to be moved and the boom adjacent to the boom to be moved.

[0016] During the telescopic operation of the telescopic boom 14, the cylinder connecting pins 454A, 454B move by the power of the electric motor 41 to release the connection between the actuator 2 and the boom. At this time, if a problem occurs in the electric motor 41, the cylinder connecting pins 454A, 454B cannot be moved, and the connection between the actuator 2 and the boom cannot be released. Therefore, the mobile crane 1 according to this embodiment is provided with a means for manually moving the cylinder connecting pins 454A, 454B to release the connection between the actuator 2 and the boom. The configuration of the mobile crane 1 according to this embodiment will be specifically described below.

[0017] As shown in FIG. 1 and FIGS. 2A to 2E, the mobile crane 1 includes a traveling body 10, a swivel base 12, a telescopic boom 14, an actuator 2, a wire rope 16, and a hook 17.

[0018] The swivel base 12 is rotatably provided on the upper part of the traveling body 10. The base end of the telescopic boom 14 is fixed to the swivel base 12, and is capable of raising and lowering and extending. The actuator 2 extends and retracts the telescopic boom 14. The wire rope 16 is supported by the telescopic boom 14, and hangs down from the tip of the telescopic boom 14. The hook 17 is provided at the tip of the wire rope 16.

[0019] Next, the telescopic boom 14 will be described with reference to Fig. 1 and Fig. 2A to Fig. 2E. The telescopic boom 14 has a plurality of booms combined in a telescopic manner. Specifically, the plurality of booms are, in order from the inside, a tip boom 141, a middle boom 142, and a base boom 143.

[0020] The telescopic boom 14 extends in sequence starting from the boom disposed inside, and transitions from the contracted state shown in Fig. 2A to the extended state shown in Fig. 1. Note that there may be multiple intermediate booms.

[0021] The tip boom 141 is cylindrical and has an internal space capable of accommodating the actuator 2. The tip boom 141 has, at its base end, a pair of cylinder pin receiving portions 141a and a pair of boom pin receiving portions 141b. Each of the pair of cylinder pin receiving portions 141a and the pair of boom pin receiving portions 141b is a through hole.

[0022] The pair of cylinder pin receiving portions 141a are coaxially provided at the base end of the tip boom 141. The pair of cylinder pin receiving portions 141a are engageable with and disengageable from a pair of cylinder connecting pins 454A, 454B provided on the cylinder member 32 of the telescopic cylinder 3, respectively.

[0023] The cylinder connecting pins 454A, 454B are each biased outward (in the direction from the base end to the tip end of the cylinder connecting pins 454A, 454B) by a first biasing mechanism 455 described below. The cylinder connecting pins 454A, 454B move inward (in the direction from the tip end to the base end of the cylinder connecting pins 454A, 454B) based on the operation of a cylinder connecting mechanism 45 described below.

[0024] With the pair of cylinder connecting pins 454A, 454B engaged with the pair of cylinder pin receiving portions 141a, the end boom 141 can move together with the cylinder member 32 in the extension / contraction direction.

[0025] The pair of boom pin receiving parts 141b are provided coaxially around the cylinder pin receiving part 141a. The boom pin receiving parts 141b can be engaged with and disengaged from the pair of boom connecting pins 144a, respectively. In the drawings, for the sake of convenience, the pair of boom pin receiving parts 141b and the pair of cylinder pin receiving parts 141a are shown in a state where they are offset in the axial direction of the telescopic boom 14. However, the pair of boom pin receiving parts 141b and the pair of cylinder pin receiving parts 141a are aligned in the axial direction of the telescopic boom 14 and are provided at positions offset in the circumferential direction of the telescopic boom 14.

[0026] Each of the pair of boom connecting pins 144a is biased outward (in the direction from the base end toward the tip end of the boom connecting pin 144a) by a second biasing mechanism 463 described below. Each of the pair of boom connecting pins 144a connects the tip boom 141 and the intermediate boom 142. The pair of boom connecting pins 144a move inward (in the direction from the tip toward the base end of the boom connecting pin 144a) based on the operation of the boom connecting mechanism 46 described below.

[0027] With the tip boom 141 and the intermediate boom 142 connected by a pair of boom connecting pins 144a, the boom connecting pin 144a is inserted so as to span between the boom pin receiving portion 141b of the tip boom 141 and the first boom pin receiving portion 142b or the second boom pin receiving portion 142c of the intermediate boom 142.

[0028] When the tip boom 141 and the intermediate boom 142 are connected to each other, the tip boom 141 is prohibited from moving relative to the intermediate boom 142. On the other hand, when the tip boom 141 and the intermediate boom 142 are not connected to each other, the tip boom 141 is movable relative to the intermediate boom 142.

[0029] The intermediate boom 142 is cylindrical and has an internal space capable of accommodating the tip boom 141. The intermediate boom 142 has a pair of cylinder pin receiving portions 142a, a pair of first boom pin receiving portions 142b, and a pair of third boom pin receiving portions 142d at its base end, and a pair of second boom pin receiving portions 142c at its tip. The pair of cylinder pin receiving portions 142a, the pair of first boom pin receiving portions 142b, the pair of third boom pin receiving portions 142d, and the pair of second boom pin receiving portions 142c are each a through hole.

[0030] The pair of cylinder pin receiving parts 142a and the pair of first boom pin receiving parts 142b are substantially similar to the pair of cylinder pin receiving parts 141a and the pair of boom pin receiving parts 141b of the tip boom 141, respectively. In the drawings, for the sake of convenience, the pair of boom pin receiving parts 142b and the pair of cylinder pin receiving parts 142a are shown in a state where they are offset in the axial direction of the telescopic boom 14. However, the pair of boom pin receiving parts 142b and the pair of cylinder pin receiving parts 142a are aligned in the axial direction of the telescopic boom 14 and are provided at positions offset in the circumferential direction of the telescopic boom 14.

[0031] The pair of third boom pin receiving portions 142d are provided coaxially with each other and closer to the base end than the pair of first boom pin receiving portions 142b. A pair of boom connecting pins 144b are inserted into the pair of third boom pin receiving portions 142d, respectively. The pair of boom connecting pins 144b connect the intermediate boom 142 and the base end boom 143.

[0032] The pair of second boom pin receiving portions 142c are provided coaxially with each other at the tip of the intermediate boom 142. A pair of boom connecting pins 144a are inserted into the pair of second boom pin receiving portions 142c, respectively.

[0033] 3, the intermediate boom 142 has a pair of emergency operation holes 142e for cylinder pins at positions coaxial with the pair of cylinder pin receiving parts 141a of the tip boom 141 when the telescopic boom 14 is in a contracted state. The base boom 143 has a pair of emergency operation holes 143a for cylinder pins at positions coaxial with the pair of cylinder pin receiving parts 141a of the tip boom 141 when the telescopic boom 14 is in a contracted state.

[0034] In addition, the base end boom 143 has a pair of emergency operation holes 143b for cylinder pins at positions coaxial with the pair of cylinder pin receiving portions 142a of the intermediate boom 142 when the telescopic boom 14 is in a contracted state. Each of the emergency operation holes 142e, 143a, 143b for cylinder pins corresponds to an example of a boom side through hole.

[0035] When there are multiple intermediate booms, each intermediate boom has an emergency operation hole for cylinder pins at a position coaxial with the cylinder pin receiving parts of all the booms arranged on the inside when the telescopic boom 14 is in the retracted state. When there are multiple intermediate booms, the base boom has an emergency operation hole for cylinder pins at a position coaxial with the cylinder pin receiving parts of all the booms arranged on the inside when the telescopic boom 14 is in the retracted state.

[0036] When manually moving the pair of cylinder connecting pins 454A, 454B, an operator can access the pair of cylinder connecting pins 454A, 454B engaged with the pair of cylinder pin receiving portions 141a of the tip boom 141 or the pair of cylinder pin receiving portions 142a of the intermediate boom 142 from the outside of the telescopic boom 14 through the emergency operation holes 142e, 143a, 143b for the cylinder pins.

[0037] The position of the emergency operation hole for the cylinder pin is not limited to the illustrated case. For example, when performing maintenance on the pin moving mechanism 4 described below, it is necessary to extend the booms (tip boom 141 and intermediate boom 142) other than the base end boom 143 to a predetermined position in order to access the pin moving mechanism 4 from a maintenance manhole (not shown) of the base end boom 143. The base end boom 143 and the intermediate boom 142 may have emergency operation holes for the cylinder pin at positions where the pair of cylinder connecting pins 454A, 454B can be manually operated from the outside of the telescopic boom 14 with the booms other than the base end boom 143 positioned at the predetermined positions.

[0038] Furthermore, the intermediate boom 142 and the base boom 143 have boom pin emergency operation holes 143c, 143d at positions that are coaxial with the boom pin receiving portions of all the booms arranged on the inside when the telescopic boom 14 is in a contracted state. In the case of the telescopic boom 14 shown in the figure, since there is one intermediate boom, the boom pin emergency operation holes 143c, 143d are provided only in the base boom 143. However, when there are multiple intermediate booms, the boom pin emergency operation holes may be provided in appropriate positions on the intermediate booms.

[0039] When performing manual operations to manually move the boom connecting pin (e.g., boom connecting pin 144a), an operator can access the boom connecting pin (e.g., boom connecting pin 144a) from the outside of the telescopic boom 14 through the boom pin emergency operation holes 143c, 143d.

[0040] In this embodiment, the cylinder pin emergency operation hole 143b and the boom pin emergency operation holes 143c and 143d are provided on the same surface of the boom, so that an operator can manually operate the cylinder connecting pin and the boom connecting pin from the same direction.

[0041] 3, for the sake of convenience, the cylinder pin emergency operation hole 143b and the boom pin emergency operation holes 143c, 143d are shown at positions shifted from each other in the extension and retraction direction of the telescopic boom 14. However, the positions of the cylinder pin emergency operation hole 143b and the boom pin emergency operation holes 143c, 143d may be appropriately determined depending on the positions of the cylinder pin receiving portion and the boom pin receiving portion.

[0042] The actuator 2 is an actuator that extends and retracts the telescopic boom 14. As shown in Fig. 2 and Fig. 4, the actuator 2 has a telescopic cylinder 3 and a pin moving mechanism 4. The actuator 2 is disposed in the internal space of the tip boom 141 when the telescopic boom 14 is in a retracted state (the state shown in Fig. 2A).

[0043] The telescopic cylinder 3 has a rod member 31 and a cylinder member 32. The telescopic cylinder 3 moves a boom connected to the cylinder member 32 via cylinder connecting pins 454A and 454B, which will be described later.

[0044] <Pin movement mechanism> The pin moving mechanism 4 has an electric motor 41 , a brake mechanism 42 , a transmission mechanism 43 , a position information detection device 44 , a cylinder connecting mechanism 45 , and a boom connecting mechanism 46 , all of which are supported by a trunnion 40 .

[0045] Hereinafter, each member constituting the actuator 2 will be described based on a state in which each member is assembled into the actuator 2. In addition, in describing the actuator 2, a Cartesian coordinate system (X, Y, Z) will be used.

[0046] In the Cartesian coordinate system, the X direction corresponds to the telescopic direction of the telescopic boom 14 when it is mounted on the mobile crane 1. The positive side of the X direction is the extension direction in the telescopic direction. The negative side of the X direction is the contraction direction in the telescopic direction. When the rotation angle of the telescopic boom 14 is 0° and the hoisting angle of the telescopic boom 14 is 0° (fully lowered state), the positive side of the X direction corresponds to the front side of the mobile crane 1. When the rotation angle of the telescopic boom 14 is 0° and the hoisting angle of the telescopic boom 14 is 0°, the negative side of the X direction corresponds to the rear side of the mobile crane 1.

[0047] Furthermore, for example, the Z direction corresponds to the up-down direction of the mobile crane 1 when the hoisting angle of the telescopic boom 14 is 0°. For example, the Y direction corresponds to the vehicle width direction (left-right direction) of the mobile crane 1 when the telescopic boom 14 faces forward. Hereinafter, when reference is made to the width direction or left-right direction without any particular mention, this refers to the Y direction in the Cartesian coordinate system (X, Y, Z).

[0048] The trunnion 40 will be described with reference to Figures 4 and 5. The trunnion 40 is fixed to the cylinder member 32 of the telescopic cylinder 3. The trunnion 40 supports a cylinder connecting mechanism 45 and a boom connecting mechanism 46. The trunnion 40 also supports an electric motor 41, a brake mechanism 42, and a transmission mechanism 43, which will be described later.

[0049] The trunnion 40 units the above-mentioned elements 41 to 46. Such a configuration contributes to a reduction in size of the pin moving mechanism 4, improvement in productivity, and improvement in the reliability of the system.

[0050] The trunnion 40 has a support hole 401. The rod member 31 of the telescopic cylinder 3 is inserted into the support hole 401 in the X direction. The trunnion 40 is fixed to the base end (the end on the negative side in the X direction) of the cylinder member 32 of the telescopic cylinder 3.

[0051] The trunnion 40 has a right recess 402 and a left recess 403 on both side walls in the left and right direction.

[0052] The right recess 402 is provided in the right wall of the trunnion 40. The right recess 402 is open at the right end and has a right bottom 402a at the left end.

[0053] The right side bottom portion 402a is provided with a right side support portion 402b. The right side support portion 402b corresponds to an example of a support portion, and is configured with a cylindrical convex portion extending rightward from the right side bottom portion 402a. The outer peripheral surface of the right side support portion 402b is cylindrical. The right side support portion 402b has a right side center hole 402c whose center axis is parallel to the left-right direction.

[0054] The right-side center hole 402c has an opening at its right end. The right-side support part 402b has a right-side threaded part 402d at the right end of the right-side center hole 402c. The right-side threaded part 402d is a female thread and is provided on the inner peripheral surface of a nut fixed (insert molded) to the right end of the right-side center hole 402c. The right-side threaded part 402d may be provided directly on the inner peripheral surface of the right-side center hole 402c.

[0055] The cylinder connecting pin 454A and the coil spring 455a of the first biasing mechanism 455 are disposed in the right recess 402. A specific arrangement of the cylinder connecting pin 454A and the coil spring 455a will be described later.

[0056] The left recess 403 is provided in the left wall of the trunnion 40. The left recess 403 is open at the left end and has a left bottom 403a at the right end.

[0057] The left side bottom portion 403a is provided with a left side support portion 403b. The left side support portion 403b corresponds to an example of a support portion, and is configured with a cylindrical convex portion extending leftward from the left side bottom portion 403a. The outer peripheral surface of the left side support portion 403b is cylindrical. The left side support portion 403b has a left side center hole 403c whose center axis is parallel to the left-right direction.

[0058] The central axis of the left central hole 403c coincides with the central axis of the right central hole 402c. The left central hole 403c has an opening at its left end. The left support part 403b has a left threaded part 403d at the left end of the left central hole 403c. The left threaded part 403d is a female thread and is provided on the inner peripheral surface of a nut fixed (insert molded) to the left end of the left central hole 403c. The left threaded part 403d may be provided directly on the inner peripheral surface of the left central hole 403c.

[0059] The cylinder connecting pin 454B and the coil spring 455b of the first biasing mechanism 455 are disposed in the left recess 403. A specific arrangement of the cylinder connecting pin 454B and the coil spring 455b will be described later.

[0060] In this embodiment, the right support portion 402b and the left support portion 403b are formed of a member that is integral with the trunnion 40. However, the right support portion and the left support portion may be formed of a member separate from the trunnion. In this case, the members that form the right support portion and the left support portion may be fixed to the trunnion by a fixing means.

[0061] The electric motor 41 is supported by the trunnion 40 (see FIG. 4). As shown in FIG. 6A, the electric motor 41 is connected to a reducer 431. The electric motor 41 is connected to, for example, a power supply device (not shown) provided on the swivel base 12 via a power supply cable.

[0062] The brake mechanism 42 applies a braking force to the electric motor 41. When the electric motor 41 is stopped, the brake mechanism 42 prevents the rotation of the output shaft of the electric motor 41. This maintains the state of the pin moving mechanism 4 when the electric motor 41 is stopped.

[0063] The brake mechanism 42 is connected to, for example, a power supply device (not shown) provided on the swivel base 12 via a power supply cable. The position information detection device 44 described below is also connected to, for example, a power supply device (not shown) provided on the swivel base 12 via a power supply cable. The position information detection device 44 is also connected to a control unit (not shown) provided on the swivel base 12 via a signal transmission cable. The power supply cable to the electric motor 41, the power supply cable to the brake mechanism 42, the power supply cable to the position information detection device 44, and the signal transmission cable of the position information detection device 44 are all integrated into one multi-core cable and arranged in the internal space of the telescopic boom 14. With this configuration, the internal space of the telescopic boom 14 can be efficiently utilized.

[0064] Specifically, the brake mechanism 42 operates when the cylinder connecting mechanism 45 or the boom connecting mechanism 46, which will be described later, is in a retracted state, to maintain the states of the cylinder connecting mechanism 45 and the boom connecting mechanism 46. The state of the brake mechanism 42 is switched by a control unit. Also, the state of the brake 42 may be switched based on an operation by an operator.

[0065] The transmission mechanism 43 transmits the power of the electric motor 41 to the cylinder connecting mechanism 45 and the boom connecting mechanism 46. The transmission mechanism 43 has a reducer 431 and a transmission shaft 432.

[0066] The reducer 431 reduces the rotation of the electric motor 41 and transmits it to the transmission shaft 432. The transmission shaft 432 transmits the rotation of the reducer 431 to a switch gear 450, which will be described later. In addition, a position information detection device 44 is provided on the tip of the transmission shaft 432, which detects information relating to the positions of the pair of cylinder connecting pins 454A, 454B and the pair of boom connecting pins 144a, 144b.

[0067] The information on the positions of the pair of cylinder connecting pins 454A, 454B and the pair of boom connecting pins 144a, 144b is, for example, the amount of movement of the pair of cylinder connecting pins 454A, 454B or the pair of boom connecting pins 144a from the reference position. The positions of the pair of cylinder connecting pins 454A, 454B shown in Fig. 6A are the reference positions of the cylinder connecting pins 454A, 454B. Also, the position of the pair of boom connecting pins 144a shown in Fig. 7A is the reference position of the boom connecting pin 144a.

[0068] <Cylinder connection mechanism> The cylinder connecting mechanism 45 operates based on the power of the electric motor 41, and transitions between an extended state (see FIG. 6A) and a contracted state (see FIG. 6C). FIGS. 6A to 6C are schematic diagrams of the pin moving mechanism 4 as viewed from the base end side (rear side) of the telescopic boom 14. The operation of the cylinder connecting mechanism 45 transitioning from the extended state to the contracted state is the extraction operation of the cylinder connecting mechanism 45. The operation of the cylinder connecting mechanism 45 transitioning from the contracted state to the extended state is the engagement operation of the cylinder connecting mechanism 45.

[0069] In the expanded state of the cylinder connecting mechanism 45, a pair of cylinder connecting pins 454A, 454B described below are engaged with a pair of cylinder pin receiving portions 141a of the boom (for example, the tip boom 141). In this engaged state, the boom and the cylinder member 32 are connected.

[0070] In addition, when the cylinder connecting mechanism 45 is in the contracted state, the pair of cylinder connecting pins 454A, 454B are disengaged from the pair of cylinder pin receiving portions 141a. In this disengaged state, the boom and the cylinder member 32 are disengaged.

[0071] Specifically, the cylinder connecting mechanism 45 has a switch gear 450, a first rack bar 451, a first gear mechanism 452, a second gear mechanism 453, a pair of cylinder connecting pins 454A, 454B, and a first biasing mechanism 455.

[0072] The switch gear 450 has teeth on a part of its outer circumferential surface. The switch gear 450 is fitted and fixed to the outside of the transmission shaft 432 and rotates together with the transmission shaft 432. The switch gear 450 selectively transmits the power of the electric motor 41 to either one of the cylinder connection mechanism 45 or the boom connection mechanism 46.

[0073] In the following description, the rotation direction of the switch gear 450 (the direction indicated by the arrow A1 in FIG. 6A) when the cylinder coupling mechanism 45 transitions from the expanded state to the contracted state is a first direction in the rotation direction of the switch gear 450. On the other hand, the rotation direction of the switch gear 450 (the direction indicated by the arrow A2 in FIG. 6A) when the cylinder coupling mechanism 45 transitions from the contracted state to the expanded state is a second direction in the rotation direction of the switch gear 450.

[0074] The first rack bar 451 moves in its own longitudinal direction (Y direction) in response to rotation of the switch gear 450. The first rack bar 451 is located at the most positive side in the Y direction when the cylinder coupling mechanism 45 is in the expanded state. On the other hand, the first rack bar 451 is located at the most negative side in the Y direction when the cylinder coupling mechanism 45 is in the contracted state.

[0075] The first rack bar 451 has a first rack tooth portion on an upper surface thereof. The first rack tooth portion meshes with the tooth portion of the switch gear 450 only during the above-mentioned state transition.

[0076] In the expanded state, when the switch gear 450 rotates a predetermined amount in the first direction, the teeth of the switch gear 450 mesh with the first rack teeth of the first rack bar 451. When the switch gear 450 further rotates in the first direction from this state, the first rack bar 451 moves to the left in response to the rotation of the switch gear 450.

[0077] When the switch gear 450 rotates in the second direction from the expanded state of the cylinder connecting mechanism 45, the first rack teeth portion of the first rack bar 451 and the teeth portion of the switch gear 450 do not mesh with each other.

[0078] Also, the first rack bar 451 has a second rack teeth portion and a third rack teeth portion on the lower surface. The second rack teeth portion meshes with a first gear mechanism 452, which will be described later. The third rack teeth portion meshes with a second gear mechanism 453, which will be described later.

[0079] The first gear mechanism 452 has a plurality of gear elements (see FIG. 6A), each of which is an external gear. The first gear mechanism 452 meshes with a second rack tooth portion of the first rack bar 451. The first gear mechanism 452 rotates in response to the movement of the first rack bar 451. The first gear mechanism 452 also meshes with a pin side rack tooth portion of a right cylinder connecting pin 454A, which will be described later.

[0080] The second gear mechanism 453 has a plurality of gear elements (see FIG. 6A), each of which is an external gear. The second gear mechanism 453 meshes with a third rack tooth portion of the first rack bar 451. The second gear mechanism 453 rotates in response to the movement of the first rack bar 451. The second gear mechanism 453 also meshes with a pin side rack tooth portion of the left cylinder connecting pin 454B, which will be described later.

[0081] 4 and 5, the pair of cylinder connecting pins 454A, 454B have respective central axes aligned in the left-right direction and are coaxial with each other. Each of the pair of cylinder connecting pins 454A, 454B corresponds to an example of a first pin, and has a through hole 454a, a countersunk portion 454d, and a pin-side rack teeth portion 454e.

[0082] The through hole 454a passes through the pair of cylinder connecting pins 454A, 454B in the axial direction. The through hole 454a has a tip side through hole 454b and a base side through hole 454c. The tip side through hole 454b and the base side through hole 454c are provided coaxially. The inner peripheral surfaces of the tip side through hole 454b and the base side through hole 454c are cylindrical surfaces. The inner diameter of the base side through hole 454c is larger than the inner diameter of the tip side through hole 454b.

[0083] In an emergency operation of the cylinder connecting mechanism 45, the shaft portion of the manual operation bolt 5 (see FIGS. 4 and 5) is inserted into the through hole 454a from the outside of the telescopic boom 14. The portion of the pair of cylinder connecting pins 454A, 454B where the base end side through hole 454c is provided is a cylindrical tube portion 454f.

[0084] The counterbore portion 454d is configured by a recess provided on the tip surfaces of the pair of cylinder connecting pins 454A and 454B. The head of the manual operation bolt 5 is placed in the counterbore portion 454d during emergency operation of the cylinder connecting mechanism 45. As shown in FIG. 5, the head of the manual operation bolt 5 placed in the counterbore portion 454d is located inside the tip surfaces of the pair of cylinder connecting pins 454A and 454B.

[0085] The pin-side rack teeth portion 454e is provided on the base end side half of the outer circumferential surface of the pair of cylinder connecting pins 454A, 454B.

[0086] The right cylinder connecting pin 454A having the above-mentioned configuration is disposed in the right recess 402 of the trunnion 40. The outer peripheral surface of the tubular portion 454f of the right cylinder connecting pin 454A closely faces the inner peripheral surface of the right recess 402. Therefore, the axial movement of the right cylinder connecting pin 454A is guided by the right recess 402. As a result, inclination of the right cylinder connecting pin 454A when it moves in the axial direction is suppressed.

[0087] The right support portion 402b of the trunnion 40 is inserted into the tubular portion 454f (base end side through hole 454c) of the right cylinder connecting pin 454A. The tubular portion 454f of the right cylinder connecting pin 454A covers the right support portion 402b of the trunnion 40 via a cylindrical space. In addition, the pin side rack teeth portion 454e of the right cylinder connecting pin 454A meshes with the first gear mechanism 452.

[0088] The left cylinder connecting pin 454B is disposed in the left recess 403 of the trunnion 40. The outer peripheral surface of the tube portion 454f of the left cylinder connecting pin 454B closely faces the inner peripheral surface of the left recess 403. Therefore, the axial movement of the left cylinder connecting pin 454B is guided by the left recess 403. As a result, inclination of the left cylinder connecting pin 454B when it moves in the axial direction is suppressed.

[0089] The left support portion 403b of the trunnion 40 is inserted into the tubular portion 454f (base end side through hole 454c) of the left cylinder connecting pin 454B. The tubular portion 454f of the left cylinder connecting pin 454B covers the left support portion 403b of the trunnion 40 via a cylindrical space. In addition, the pin side rack teeth portion 454e of the left cylinder connecting pin 454B meshes with the second gear mechanism 453.

[0090] The right cylinder connecting pin 454A moves in its axial direction in response to rotation of the first gear mechanism 452. Specifically, the right cylinder connecting pin 454A moves to the right (outside) when the cylinder connecting mechanism 45 transitions from the contracted state (see FIG. 5) to the expanded state (see FIG. 4). On the other hand, the right cylinder connecting pin 454A moves to the left (inside) when the cylinder connecting mechanism 45 transitions from the expanded state to the contracted state.

[0091] The left cylinder connecting pin 454B moves in its axial direction in response to rotation of the second gear mechanism 453. Specifically, the left cylinder connecting pin 454B moves to the left when the cylinder connecting mechanism 45 transitions from the contracted state to the expanded state. On the other hand, the left cylinder connecting pin 454B moves to the right when the cylinder connecting mechanism 45 transitions from the expanded state to the contracted state.

[0092] In addition, the tip end through hole 454b of the right cylinder connecting pin 454A and the right center hole 402c of the trunnion 40 are arranged coaxially. In addition, the tip end through hole 454b of the left cylinder connecting pin 454B and the left center hole 403c of the trunnion 40 are arranged coaxially.

[0093] When the cylinder connecting pins 454A, 454B are positioned at the deepest (inner) part of the right recess 402 and the left recess 403 (hereinafter referred to as the contracted state of the cylinder connecting pins 454A, 454B), the tip surfaces of the cylinder connecting pins 454A, 454B are positioned inner than both side surfaces of the trunnion 40 in the left-right direction.

[0094] When the cylinder connecting pins 454A, 454B move outward from their contracted state, the tips of the cylinder connecting pins 454A, 454B protrude outward beyond both side surfaces of the trunnion 40. The state in which the cylinder connecting pins 454A, 454B move to the outermost position is referred to as the expanded state of the cylinder connecting pins 454A, 454B. In the expanded state, the cylinder connecting pins 454A, 454B engage with the cylinder pin receiving portion of the boom.

[0095] The first biasing mechanism 455 returns the cylinder connecting mechanism 45 to the extended state when the electric motor 41 is de-energized with the cylinder connecting mechanism 45 in the contracted state. In other words, the first biasing mechanism 455 returns the pair of cylinder connecting pins 454A, 454B to the reference position when the electric motor 41 is de-energized (stopped) and the brake mechanism 42 is turned off with the cylinder connecting mechanism 45 in the contracted state.

[0096] Specifically, the first biasing mechanism 455 has a pair of coil springs 455a, 455b (see FIGS. 4 and 5). The right coil spring 455a is provided between the right support portion 402b of the trunnion 40 and the tube portion 454f of the right cylinder connecting pin 454A so as to cover the outer circumferential surface of the right support portion 402b.

[0097] The right coil spring 455a constantly biases the right cylinder connecting pin 454A. The direction in which the right coil spring 455a biases the cylinder connecting pin 454A coincides with the direction (right side) from the base end to the tip end of the cylinder connecting pin 454A.

[0098] The left coil spring 455b is provided between the left support portion 403b of the trunnion 40 and the tube portion 454f of the left cylinder connecting pin 454B so as to cover the outer circumferential surface of the left support portion 403b. The left coil spring 455b constantly biases the left cylinder connecting pin 454B. The direction in which the left coil spring 455b biases the left cylinder connecting pin 454B coincides with the direction (left side) from the base end toward the tip end of the cylinder connecting pin 454B.

[0099] The configuration of the first biasing mechanism 455 as described above contributes to the miniaturization of the pin moving mechanism 4. The arrangement of the coil springs 455a, 455b is not limited to that of this embodiment. The operation of the cylinder connecting mechanism 45 will be described later.

[0100] <Boom connection mechanism> The boom connection mechanism 46 transitions between an extended state (see FIG. 7A) and a retracted state (see FIG. 7C) based on the rotation of the electric motor 41. FIGS. 7A to 7C are schematic diagrams of the pin moving mechanism 4 as viewed from the base end side (rear side) of the telescopic boom 14. The operation of the boom connection mechanism 46 transitioning from the extended state to the retracted state is the extraction operation of the boom connection mechanism 46. The operation of the boom connection mechanism 46 transitioning from the retracted state to the extended state is the insertion operation of the boom connection mechanism 46.

[0101] In the extended state, the boom connection mechanism 46 can be in either an engaged state or a disengaged state with respect to a boom connection pin (e.g., a pair of boom connection pins 144a). The boom connection mechanism 46, in a state engaged with the boom connection pin, disengages the boom connection pin from the boom by transitioning from the extended state to the contracted state.

[0102] In addition, the boom connection mechanism 46, while engaged with the boom connecting pin, transitions from a contracted state to an extended state, thereby engaging the boom connecting pin with the boom.

[0103] 4 to 7C, the boom connecting mechanism 46 has a switch gear 450, a pair of second rack bars 461a, 461b, a synchronous gear 462 (see FIG. 7A), and a second biasing mechanism 463. The switch gear 450 is a gear shared with the cylinder connecting mechanism 45.

[0104] The pair of second rack bars 461a, 461b are, for example, shaft members that are long in the left-right direction and are arranged in parallel while being spaced apart in the front-rear direction. The pair of second rack bars 461a, 461b are each arranged above the first rack bar 451 of the cylinder connecting mechanism 45.

[0105] The pair of second rack bars 461a, 461b each have a synchronizing rack tooth portion on an opposing surface. The synchronizing rack tooth portion each meshes with a synchronizing gear 462 (see FIG. 7A). When the synchronizing gear 462 rotates, one (front) second rack bar 461a and the other (rear) second rack bar 461b move in opposite directions in the left-right direction.

[0106] The pair of second rack bars 461a, 461b have locking claws 461g, 461h (see FIG. 7A) at their tips, respectively. When moving a boom connecting pin (for example, boom connecting pins 144a, 144b), the locking claws 461g, 461h engage with pin side receiving portions 144c (see FIG. 7A) provided on the boom connecting pin.

[0107] One of the second rack bars 461a has a driving rack tooth portion 461c (see FIG. 7A) on a surface facing the switch gear 450. The driving rack tooth portion 461c meshes with the tooth portion of the switch gear 450 when the switch gear 450 rotates a predetermined amount in the second direction (the direction indicated by the arrow A2 in FIG. 7A).

[0108] When the switch gear 450 rotates a predetermined amount in the second direction from the expanded state of the boom connection mechanism 46, the driving rack tooth portion 461c meshes with the tooth portion of the switch gear 450. When the switch gear 450 rotates further in the second direction, one of the second rack bars 461a moves to the left based on the meshing between the driving rack tooth portion 461c and the tooth portion of the switch gear 450.

[0109] Moreover, when one second rack bar 461a moves to the left, the synchronous gear 462 rotates, and the other second rack bar 461b moves to the right.

[0110] When the electric motor 41 is de-energized and the brake mechanism 42 is turned off while the boom connection mechanism 46 is in the contracted state, the second biasing mechanism 463 returns the boom connection mechanism 46 to the extended state. The second biasing mechanism 463 biases the pair of second rack bars 461a, 461b in directions away from each other.

[0111] Specifically, the second biasing mechanism 463 is composed of a pair of coil springs 463a, 463b (see FIG. 7A). The pair of coil springs 463a, 463b bias the base ends of the pair of second rack bars 461a, 461b toward the tip side, respectively.

[0112] <Operation of the connecting mechanism> An example of the operation of the cylinder connecting mechanism 45 and the boom connecting mechanism 46 will now be described.

[0113] <Operation of cylinder connection mechanism> An example of the operation of the cylinder coupling mechanism 45 will be described with reference to Figures 2A to 2E and 6A to 6C. First, the normal operation of the cylinder coupling mechanism 45 will be described. The normal operation of the cylinder coupling mechanism 45 is the operation when the cylinder coupling mechanism 45 transitions from the expanded state to the contracted state based on the power of the electric motor 41, and the operation when the cylinder coupling mechanism 45 transitions from the contracted state to the expanded state based on the biasing force of the first biasing mechanism 455. Next, the operation of the cylinder coupling mechanism 45 in an emergency will be described. The emergency operation of the cylinder coupling mechanism 45 is the operation when the cylinder coupling mechanism 45 transitions from the expanded state to the contracted state or from the contracted state to the expanded state by manual operation by the operator.

[0114] Fig. 6A is a schematic diagram showing the expanded state of the cylinder connecting mechanism 45 and the engagement state between the pair of cylinder connecting pins 454A, 454B and the pair of cylinder pin receiving portions 141a of the tip boom 141. Fig. 6B is a schematic diagram showing the state in which the cylinder connecting mechanism 45 is in the middle of transitioning from the expanded state to the contracted state. Furthermore, Fig. 6C is a schematic diagram showing the contracted state of the cylinder connecting mechanism 45 and the disengagement state between the pair of cylinder connecting pins 454A, 454B and the pair of cylinder pin receiving portions 141a of the tip boom 141.

[0115] The expanded state of the cylinder connecting mechanism 45 shown in Fig. 6A corresponds to the state of the cylinder connecting mechanism 45 in Fig. 2A to Fig. 2D. The state of the cylinder connecting mechanism 45 shown in Fig. 6B corresponds to a state in the middle of transition from the state of the cylinder connecting mechanism 45 shown in Fig. 2D to the state of the cylinder connecting mechanism 45 shown in Fig. 2E. The contracted state of the cylinder connecting mechanism 45 shown in Fig. 6C corresponds to the state of the cylinder connecting mechanism 45 shown in Fig. 2E.

[0116] When the cylinder connecting mechanism 45 transitions from the expanded state to the contracted state, a control unit (not shown) drives the electric motor 41. The power of the electric motor 41 is transmitted to a pair of cylinder connecting pins 454A, 454B via the following first and second transmission paths.

[0117] The first transmission path is a path through which the power of the electric motor 41 is transmitted in the following order. (First transmission path) Switch gear 450 → First rack bar 451 → First gear mechanism 452 → Right cylinder connecting pin 454A

[0118] The second transmission path is a path through which the power of the electric motor 41 is transmitted in the following order. (Second transmission path) Switch gear 450 → First rack bar 451 → Second gear mechanism 453 → Left cylinder connecting pin 454B

[0119] Specifically, first, in the first transmission path and the second transmission path, the switch gear 450 rotates in a first direction (the direction indicated by the arrow A1 in FIG. 6A) based on the power of the electric motor 41.

[0120] In the first transmission path, when the switch gear 450 rotates in the first direction, the first rack bar 451 moves to the left in response to the rotation. Then, in the first transmission path, when the first rack bar 451 moves to the left, the right cylinder connecting pin 454A moves to the left via the first gear mechanism 452.

[0121] On the other hand, in the second transmission path, when the first rack bar 451 moves to the left, the left cylinder connecting pin 454 B moves to the right via the second gear mechanism 453 .

[0122] The position information detection device 44 detects that the pair of cylinder connecting pins 454A, 454B have been released from the pair of cylinder pin receiving portions 141a of the tip boom 141 and have moved to a predetermined position (for example, the position shown in FIG. 6C). Then, based on the detection result, the control unit (not shown) stops the operation of the electric motor 41.

[0123] In addition, the transition of the cylinder connecting mechanism 45 from the contracted state to the expanded state is automatically performed based on the biasing force of the first biasing mechanism 455 when the brake mechanism 42 is in the OFF state while the electric motor 41 is in the non-energized state.

[0124] Next, the operation of the cylinder coupling mechanism 45 in an emergency will be described. In the expanded state of the cylinder coupling mechanism 45 shown in Figs. 2A, 3, and 6A, if a trouble occurs that prevents the electric motor 41 from operating normally (hereinafter referred to as a "trouble related to the motor"; for example, a power loss), the cylinder coupling mechanism 45 cannot be transitioned from the expanded state to the contracted state. If a trouble related to the motor occurs when the tip boom and the intermediate boom are extended, the entire telescopic boom may not be able to be returned to the contracted state. In the case of this embodiment, the cylinder coupling mechanism 45 can be transitioned from the expanded state to the contracted state by manual operation by the operator, so that even if a trouble related to the motor occurs, the entire telescopic boom can be returned to the contracted state. The reason for this will be described below.

[0125] For example, if a problem occurs with the motor in the state shown in Figure 2C or Figure 2D, the connection between the cylinder connecting pins 454A, 454B and the boom tip 141 cannot be released, and the telescopic cylinder 3 cannot be returned alone to the position shown in Figures 2A and 2B. Therefore, the extension operation of the telescopic boom 14 cannot continue.

[0126] In this case, first, the operator returns the tip boom 141 together with the telescopic cylinder 3 (cylinder connecting mechanism 45) to the position shown in Figures 2A, 2B, and 3. In the state shown in Figures 2A, 2B, and 3, the cylinder connecting pins 454A, 454B, the cylinder pin emergency operation hole 143a of the base boom 143, and the cylinder pin emergency operation hole 142e of the intermediate boom 142 are coaxially positioned. When returning the tip boom 141 to the position shown in Figures 2A, 2B, and 3, the boom connecting mechanism 46 is manually operated to release the connection between the tip boom 141 and the intermediate boom 142 by the boom connecting pin 144a, if necessary.

[0127] In this state, the operator inserts the manual operation bolt 5 (see Figs. 3 to 5) into the through hole 454a of the right cylinder connecting pin 454A from the outside of the right side plate portion of the telescopic boom 14. In other words, the manual operation bolt 5 passes through the cylinder pin emergency operation hole 143a of the base end boom 143 and the cylinder pin emergency operation hole 142e of the intermediate boom 142, and is inserted into the through hole 454a of the cylinder connecting pin 454A. The manual operation bolt 5 is inserted into the through hole 454a of the cylinder connecting pin 454A in a state where it is engaged with a tool (not shown).

[0128] Then, the worker screws the male threaded portion provided on the outer circumferential surface of the shaft portion of the manual operation bolt 5 into the right-side threaded portion 402d of the right-side support portion 402b of the trunnion 40 (see FIG. 4). In this state, the head of the manual operation bolt 5 is disposed in the counterbore portion 454d of the right-side cylinder connecting pin 454A. With the male threaded portion of the manual operation bolt 5 and the right-side threaded portion 402d of the right-side support portion 402b screwed together by a predetermined amount, the head of the manual operation bolt 5 abuts against the counterbore portion 454d of the right-side cylinder connecting pin 454A.

[0129] The operator rotates the manual operation bolt 5 from the state shown in Fig. 4. Then, the manual operation bolt 5 moves inward (in the direction from the head to the tip of the manual operation bolt 5, to the left in Fig. 4) based on the engagement between the male thread of the manual operation bolt 5 and the right thread 402d of the right support part 402b.

[0130] As a result, the right cylinder connecting pin 454A is pushed by the head of the manual operation bolt 5 and moves inward (to the left in FIG. 4). At this time, the right cylinder connecting pin 454A moves against the elastic force of the right coil spring 455a of the first biasing mechanism 455. Therefore, the right coil spring 455a contracts in response to the inward movement of the right cylinder connecting pin 454A.

[0131] The right cylinder connecting pin 454A moves until its tip surface abuts against the right bottom portion 402a of the trunnion 40. In other words, the right bottom portion 402a functions as a stopper that restricts the inward movement of the right cylinder connecting pin 454A to a predetermined amount.

[0132] Furthermore, when the right cylinder connecting pin 454A moves inward, the left cylinder connecting pin 454B also moves inward in synchronization with the right cylinder connecting pin 454A.

[0133] Specifically, when the right cylinder connecting pin 454A moves inward, the first gear mechanism 452 rotates based on the meshing of the pin side rack teeth portion 454e of the right cylinder connecting pin 454A with the first gear mechanism 452. Next, when the first gear mechanism 452 rotates, the first rack bar 451 moves to the left, and the second gear mechanism 453 rotates.

[0134] When the second gear mechanism 453 rotates, the left pin side rack teeth portion 454e moves inward based on the meshing between the second gear mechanism 453 and the pin side rack teeth portion 454e of the left cylinder connecting pin 454B. At this time, the left cylinder connecting pin 454B moves inward against the elastic force of the left coil spring 455b of the first biasing mechanism 455. Therefore, the left coil spring 455b contracts in response to the inward movement of the left cylinder connecting pin 454B.

[0135] The position of the right cylinder connecting pin 454A (position shown in FIG. 5) is maintained in the position after movement by the manual operation bolt 5. In other words, even after the operator removes the tool from the manual operation bolt 5, the position of the right cylinder connecting pin 454A is maintained in the position after movement. In addition, the position of the left cylinder connecting pin 454B is also maintained in the position after movement by the manual operation bolt 5.

[0136] When the cylinder connecting pins 454A, 454B move to the position shown in FIG. 5, the cylinder connecting mechanism 45 enters a contracted state, and the connection between the telescopic cylinder 3 and the boom (the tip boom 141 in the illustrated case) is released.

[0137] In the above explanation, the case where the connection between the telescopic cylinder 3 and the boom tip 141 is released by manual operation has been described. The procedure for manually releasing the connection between the telescopic cylinder 3 and the intermediate boom 142 is almost the same as the above explanation. Also, in the above explanation, the procedure for moving the right cylinder connecting pin 454A by the manual operation bolt 5 has been described. However, the left cylinder connecting pin 454B may also be moved by the manual operation bolt 5.

[0138] In the telescopic boom 14 shown in Fig. 2, if a problem occurs with the motor while the tip boom 141 and the intermediate boom 142 are extended and the telescopic cylinder 3 and the intermediate boom 142 are connected, the operator can repeat the above-mentioned procedure as appropriate to retract the entire telescopic boom 14. Even if the number of booms constituting the telescopic boom is four or more, the operator can repeat the above-mentioned procedure as appropriate to retract the entire telescopic boom.

[0139] In some cases, the operator may need to manually release the connection between the booms. For this reason, in this embodiment, the boom connecting pin has a mechanism that can transition from the extended state to the retracted state based on the operator's manual operation. This mechanism is similar to a conventionally known mechanism, so a detailed description will be omitted.

[0140] The operation of releasing the connection between such booms is performed, for example, by manually operating the boom connection pin 144a with a tool (not shown) inserted into the boom pin emergency operation hole 143c from the outside of the telescopic boom 14.

[0141] In this embodiment, the cylinder pin emergency operation hole 143b and the boom pin emergency operation holes 143c, 143d are provided on the same surface of the boom, so the operator can perform the manual operation for releasing the connection between the telescopic cylinder 3 and the boom and the manual operation for releasing the connection between the booms from the same direction (i.e., the direction indicated by the arrow A3 in FIG. 3). This configuration contributes to improving the operability of manual operation.

[0142] In order to further improve the ease of manual operation, it is preferable that the tool used when manually releasing the connection between the booms be of the same standard as the tool used when manually releasing the connection between the telescopic cylinder 3 and the boom.

[0143] <Boom connection mechanism operation> Next, an example of the operation of the above-mentioned boom connecting mechanism 46 will be described with reference to FIGS. 2A to 2E and 7A to 7C.

[0144] Fig. 7A is a schematic diagram showing the boom connection mechanism 46 in an extended state, and an engaged state between the pair of boom connecting pins 144a and the pair of first boom pin receivers 142b of the intermediate boom 142. Fig. 7B is a schematic diagram showing the boom connection mechanism 46 in the middle of transitioning from the extended state to the contracted state. Furthermore, Fig. 7C is a schematic diagram showing the boom connection mechanism 46 in a contracted state, and a disengaged state between the pair of boom connecting pins 144a and the pair of first boom pin receivers 142b of the intermediate boom 142.

[0145] The expanded state of the boom connection mechanism 46 shown in Figure 7A corresponds to the state of the boom connection mechanism 46 in Figure 2A. The state of the boom connection mechanism 46 shown in Figure 7B corresponds to a state in the middle of transition from the state of the boom connection mechanism 46 shown in Figure 2A to the state of the boom connection mechanism 46 shown in Figure 2B. The contracted state of the boom connection mechanism 46 shown in Figure 7C corresponds to the state of the boom connection mechanism 46 shown in Figure 2B.

[0146] The boom connection mechanism 46 transitions between an extended state and a retracted state based on the power of the electric motor 41. Here, the position of the switch gear 450 shown in FIG.

[0147] When the boom connection mechanism 46 transitions from the extended state to the retracted state, a control unit (not shown) drives the electric motor 41 in a direction opposite to that in which the cylinder connection mechanism 45 is operated. The power of the electric motor 41 is transmitted through the following path. (Transmission path) Switch gear 450 → one second rack bar 461a → synchronous gear 462 → other second rack bar 461b

[0148] First, in the transmission path, the switch gear 450 rotates in a second direction (the direction indicated by the arrow A2 in FIG. 7A) in the rotational direction of the switch gear 450 based on the power of the electric motor 41. When the switch gear 450 rotates in the second direction, one of the second rack bars 461a moves to the right in response to the rotation.

[0149] Then, in response to the movement of one second rack bar 461a to the right, the synchronization gear 462 rotates. Then, in response to the rotation of the synchronization gear 462, the other second rack bar 461b moves to the left.

[0150] When the pair of second rack bars 461a, 461b are engaged with the pair of boom connecting pins 144a and transition from the extended state to the contracted state, the pair of boom connecting pins 144a disengage from the pair of first boom pin receiving portions 142b of the intermediate boom 142 (see Figure 7C).

[0151] The position information detection device 44 detects that the pair of boom connecting pins 144a have been released from the pair of first boom pin receiving portions 142b of the intermediate boom 142 and have moved to a predetermined position (for example, the position shown in FIG. 7C). Then, based on this detection result, the control unit stops the operation of the electric motor 41.

[0152] When the brake mechanism 42 is turned off while the electric motor 41 is in a non-energized state, the closing operation of the boom connecting mechanism 46 is automatically performed based on the biasing force of the second biasing mechanism 463. During this state transition, the pair of boom connecting pins 144a move in directions away from each other.

[0153] The position information detection device 44 detects that the pair of boom connecting pins 144a engage with the pair of first boom pin receiving portions 142b of the intermediate boom 142 and move to a predetermined position (for example, the position shown in FIG. 7C). The detection result is used to control the next operation of the actuator 2.

[0154] <Actions and Effects of This Embodiment> In the case of the mobile crane 1 of this embodiment having the above-mentioned configuration, even if a problem occurs with the motor, as described above, the cylinder connecting mechanism 45 can be transitioned from the extended state to the contracted state by manual operation, so that the connection between the cylinder connecting pins 454A, 454B and the boom can be released.

[0155] <Additional Notes> The technical ideas disclosed in the specification and drawings include inventions obtained by combining the various configurations described in the above embodiments in any desired manner. In particular, the technical ideas disclosed in the specification and drawings include inventions obtained by applying the various configurations disclosed in the specification and drawings in any desired combination to the above basic configuration. [Industrial Applicability]

[0156] The crane according to the present invention is not limited to a rough terrain crane, but may be, for example, various types of mobile cranes such as an all-terrain crane, a truck crane, or a loaded truck crane (also called a cargo crane). Furthermore, the crane according to the present invention is not limited to a mobile crane, but may be any other crane equipped with a telescopic boom. [Explanation of symbols]

[0157] 1 Mobile crane 10 Running body 12 Swivel table 14 Telescopic boom 141 Boom tip 141a Cylinder pin receiving part 141b Boom pin receiver 142 Intermediate boom 142a Cylinder pin receiving part 142b First boom pin receiver 142c Second boom pin receiver 142d Third boom pin receiver 142e Emergency operation hole for cylinder pin 143 Base boom 143a, 143b Emergency operation hole for cylinder pin 143c, 143d Emergency operation hole for boom pin 144a, 144b Boom connecting pin 144c Pin side receiving part 16 Wire Rope 17 Hook 2 Actuators 3 Telescopic cylinder 31 Rod member 32 Cylinder parts 4 Pin movement mechanism 40 Trunnion 401 Support hole 402 Right side recess 402a Bottom right side 402b Right side support part 402c Right center hole 402d Right Thread 403 Left recess 403a Bottom left side 403b Left side support 403c Left center hole 403d Left Thread 41 Electric motor 42 Brake mechanism 43 Transmission Mechanism 431 Reducer 432 Transmission shaft 44 Location information detection device 45 Cylinder connection mechanism 450 Switchgear 451 First Rack Bar 452 First Gear Mechanism 453 Second Gear Mechanism 454A, 454B Cylinder connecting pin 454a Through hole 454b Tip side through hole 454c Proximal through hole 454d Countersink 454e Pin side rack teeth 454f Cylinder part 455 First biasing mechanism 455a, 455b Coil spring 46 Boom connection mechanism 461a, 461b Second rack bar 461c Driving rack teeth 461g, 461h Locking claw part 462 Synchronous Gear 463 Second biasing mechanism 463a, 463b Coil spring 5 Manual operation bolt

Claims

1. A telescopic cylinder; A plurality of booms that are extended and retracted by the power of the telescopic cylinder; a first pin having a through hole penetrating in an axial direction, the first pin being moved by a spring to connect the boom and the telescopic cylinder and being moved by the power of a motor to release the connection; a trunnion provided on the telescopic cylinder, movably supporting the first pin, and having a support portion that can be screwed into a manually operated screw member inserted into the through hole from the outside of the boom, When the manually operated screw member is rotated in a state in which the manually operated screw member and the support portion are screwed together, the first pin moves together with the manually operated screw member, and the connection is released. Work machine.

2. the boom has a boom-side through-hole that is arranged coaxially with the through-hole when the boom and the telescopic cylinder are connected to each other and when the plurality of booms are contracted, The work machine according to claim 1 , wherein the manually operated screw member is inserted through the boom side through hole into the through hole.

3. The first pin has a cylindrical portion arranged to cover the support portion, The work machine according to claim 1 or 2, wherein the spring is disposed between the cylindrical portion and the support portion.

4. The support portion is configured by a protrusion having a cylindrical outer peripheral surface. The work machine according to claim 3 , wherein the spring is a coil spring arranged to cover the support portion.

5. The work machine according to any one of claims 1 to 4, wherein the first pin is constituted by a pair of pins that move synchronously based on the screw engagement.

6. The work machine according to any one of claims 1 to 5, wherein the first pin remains in a position after being moved based on rotation of the manually operated screw member by engaging with the manually operated screw member.

7. Further comprising a second pin connecting the two adjacent overlapping booms, The outer boom, which is the boom disposed outboard of the two booms, an emergency operation hole for a first pin through which the manual operation screw member is inserted from the outside of the outer boom when the first pin is manually operated to release the connection between the telescopic cylinder and the boom; and a second pin emergency operation hole through which a tool is inserted from the outside of the outer boom when the second pin is manually operated to release the connection between the two booms, The first pin emergency operation hole and the second pin emergency operation hole are provided on the same surface of the outer boom. The work machine according to claim 1.

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