Ascent / descent step for work vehicle

Abstract

To provide an ascent / descent step for a work vehicle capable of preventing damage.SOLUTION: An ascent / descent step comprises: a front side connection member and a rear side connection member which are arranged with a space to each other in a vehicle longitudinal direction at a side position of a vehicle body, and in which connection parts with the vehicle body are connected rotatably around a rotary shaft; and at least one step board in which both end parts in the vehicle longitudinal direction are connected rotatably around the rotary shaft with respective lower end parts of the front side connection member and the rear side connection member or portions located above the lower end parts, wherein the rotary shaft at the connection parts between the vehicle body and each of the front side connection member and the rear side connection member and the rotary shaft at both end parts of the step board are arranged in parallel with each other and are oblique in a vehicle width direction when viewed in the vehicle longitudinal direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a lifting step of a work vehicle.

Background Art

[0002] In a work vehicle such as a wheel loader, a configuration including a lifting step is disclosed for an operator to move back and forth between the ground and the engine room. One of the operations performed by a wheel loader is a scraping operation. This operation is to climb while excavating the natural ground in front of the vehicle. As the wheel loader climbs the natural ground during the scraping operation, the front side of the vehicle body inclines upward. In the lifting step of the wheel loader, a portion that hangs downward beyond the departure angle defining line connecting the ground contact portion of the rear wheel and the lower surface of the counterweight behind the vehicle may come into contact with the ground and be damaged during the scraping operation. Therefore, in the lifting steps of Patent Document 1 and Patent Document 2, both ends of the upper and lower treads in the vehicle front-rear direction are rotatably connected to each of the front-side connecting member and the rear-side connecting member that are arranged at intervals in the vehicle front-rear direction at the side position of the vehicle body. Thereby, even if the lower tread contacts the ground during the scraping operation, the lifting step is folded and escapes by rotation at each connecting portion, and it is said that damage to the lower tread or the like can be prevented.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the lifting steps of Patent Document 1 and Patent Document 2, when rotating at each connecting part during the scraping-up operation, the upper and lower tread plates may come into contact with each other. In this case, the tread plate itself may be crushed and damaged.

[0005] Therefore, an object of the present invention is to provide a lifting step of a work vehicle that can suppress damage.

Means for Solving the Problems

[0006] The lifting step of the work vehicle according to one aspect of the present invention includes a front-side connecting member and a rear-side connecting member that are arranged at intervals in the vehicle front-rear direction at a side position of the vehicle body and whose connecting parts with the vehicle body are rotatably connected about a rotation axis, and at least one tread plate whose both end parts in the vehicle front-rear direction are rotatably connected about a rotation axis to each of the lower end parts of the front-side connecting member and the rear-side connecting member or parts located above the lower end parts. When viewed from the vehicle front-rear direction, the rotation axes at the connecting parts of the front-side connecting member and the rear-side connecting member with the vehicle body and the rotation axes at both end parts of the tread plate are arranged parallel to each other and inclined with respect to the vehicle width direction.

Effects of the Invention

[0007] According to the above aspect, damage can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments, a wheel loader will be described as a work vehicle equipped with a lifting step.

[0010] In the following description, expressions indicating relative or absolute arrangements such as "parallel", "orthogonal", "center", "coaxial", etc. not only strictly mean such arrangements and states, but also include arrangements and states in which they are relatively displaced with tolerances and angles and distances that can obtain the same function. In the drawings used in the following description, in order to make each member recognizable in size, the scale of each member may be appropriately changed and shown.

[0011] <First Embodiment> Fig. 1 is a side view of a wheel loader 1 equipped with a lifting step 10 according to the first embodiment. As shown in Fig. 1, the wheel loader 1 includes a vehicle body 2, a working machine 3, a cab 4, a traveling device 5, and a power unit 6.

[0012] Hereinafter, the forward direction (front of the vehicle), reverse direction (rear of the vehicle), and vehicle width direction (left - right direction of the vehicle) of the wheel loader 1 (work vehicle) may be referred to as "front", "rear", and "left - right direction", respectively. The right hand with respect to the direction in which the vehicle moves forward is called the right side, and the left hand with respect to the direction in which the vehicle moves forward is called the left side. The vehicle vertical direction, the upper part of the vehicle, and the lower part of the vehicle may be simply referred to as "vertical direction", "upper part", and "lower part", respectively. In the example of the figure, the vehicle is arranged on a horizontal plane (horizontal ground GL). The vehicle vertical direction, the upper part of the vehicle, and the lower part of the vehicle respectively coincide with the vertical direction (vertical direction), vertically upward, and vertically downward when the vehicle is arranged on the horizontal plane.

[0013] The vehicle body 2 is composed of a frame body that supports the work implement 3, the cab 4, and the power unit 6. In front of the vehicle body 2, a structure 21 is provided rotatably in the left - right direction with respect to the vehicle body 2. In front of the structure 21, the work implement 3 is provided.

[0014] The work implement 3 is a machine for excavating or transporting work objects such as earth and sand. The work implement 3 includes a boom 31, a bucket 32, a bell crank 33, a lift cylinder (not shown), a tilt cylinder 34, etc.

[0015] A pair of booms 31 are provided in the vehicle width direction. The boom 31 is supported rotatably up and down with respect to the structure 21. The base end of the lift cylinder supported at the middle part of the boom 31 is supported by the structure 21. By expanding and contracting this lift cylinder hydraulically, the boom 31 rotates up and down.

[0016] The bucket 32 is a part for loading excavated soil, etc. The bucket 32 is supported at the lower end of the bell crank 33 via a link (not shown) supported above the support position with the boom 31. The bell crank 33 is provided between the pair of booms 31. The tip of the tilt cylinder 34 is supported at the upper end of the bell crank 33. The base end of the tilt cylinder 34 is supported by the structure 21.

[0017] For example, with the bucket 32 positioned near the ground level, the vehicle moves forward while extending the lift cylinder and inserting the bucket 32 into the object to be excavated such as earth and sand. Then, the boom 31 rotates upward with the excavated soil loaded in the bucket 32, enabling the excavation work. Further, when the tilt cylinder 34 is contracted with the bucket 32 positioned upward, the upper end portion of the bell crank 33 rotates toward the vehicle body 2 side, and the lower end portion of the bell crank 33 rotates forward. Then, the upper part of the bucket 32 is pushed forward by the link. As a result, the bucket 32 rotates, and the excavated soil loaded in the bucket 32 can be unloaded onto the loading platform of a dump truck or the like.

[0018] The traveling device 5 includes front wheels 5A and rear wheels 5B provided on the left and right side surfaces of the vehicle body 2, a front axle (not shown) that rotatably supports the front wheels 5A, a rear axle (not shown) that rotatably supports the rear wheels 5B, and a drive shaft (not shown) connected to each axle via a differential.

[0019] The power unit 6 is mounted on the rear part of the vehicle body 2. An engine (not shown) is provided inside the power unit 6. The drive shaft of the traveling device 5 is connected to the engine via a torque converter (not shown). When the engine rotates, the rotational speed is converted by a transmission (not shown) via the torque converter, and the drive shaft rotates. The rotation of the drive shaft is transmitted to the front wheels 5A and the rear wheels 5B via the differential and each axle. Thereby, the wheel loader 1 travels.

[0020] At the side position of the vehicle body 2 (side surface 2C in the figure), between the rear end 2A of the vehicle body 2 and the rear wheel 5B, there is an elevating step 10 for the operator and the maintenance man to move back and forth between the ground and the engine room. In such an elevating step 10, in recent years, it has been desired to lower the height from the ground GL so that access can be made easier, and the length of the hanging part from the vehicle body 2 has become longer than before. For example, the height of the elevating step 10 from the ground GL (the distance between the lower end of the elevating step 10 and the ground GL) is set to 600 mm or less. As a result, the lower end side of the elevating step 10 will hang down greatly exceeding the departure angle regulation line DL compared to the conventional case. The departure angle regulation line DL is a line connecting the lower surface (rear end 2A) of the counterweight 2B as the rear lower part of the vehicle body 2 and the grounding part of the rear wheel 5B, and is a line that defines the departure angle θ.

[0021] One of the operations by the wheel loader 1 is the scraping-up operation. This operation is an operation of climbing while excavating the natural ground in front of the vehicle with the bucket 32. The wheel loader 1 inclines so that the front side of the vehicle body 2 faces upward as it climbs the natural ground during the scraping-up operation. The maximum inclinable range at this time is determined by the departure angle θ. For this reason, during the scraping-up operation, the vehicle body 2 may be inclined to the maximum extent, and the part that hangs down beyond the departure angle regulation line DL of the elevating step 10 comes into contact with the ground GL. For this reason, generally, the elevating step 10 adopts a folding structure that folds and escapes when contacting the ground GL. Also in the elevating step 10 of the present embodiment, by adopting the folding structure, the problem that occurs when the part that hangs down beyond the departure angle regulation line DL becomes longer is solved. Hereinafter, the elevating step 10 will be described in detail.

[0022] <Elevating Step> FIG. 2 is a perspective view of the elevating step 10 according to the first embodiment. FIG. 3 is a top view of the elevating step 10 and is a view taken in the direction of arrow III in FIG. 2. FIG. 4 is a bottom view of the elevating step 10 and is a view taken in the direction of arrow IV in FIG. 2. FIG. 5 is an outer view of the elevating step 10 in the vehicle width direction and is a view taken in the direction of arrow V in FIG. 2. FIG. 6 is an inner view of the elevating step 10 in the vehicle width direction and is a view taken in the direction of arrow VI in FIG. 2. FIG. 7 is a front view of the elevating step 10 and is a view taken in the direction of arrow VII in FIG. 2. FIG. 8 is a rear view of the elevating step 10 and is a view taken in the direction of arrow VIII in FIG. 2.

[0023] Referring to FIGS. 2 to 8 together, the elevating step 10 includes a front connecting member 11 and a rear connecting member 12 which are arranged at lateral positions of the vehicle body 2 with a space therebetween in the vehicle longitudinal direction, and a first pedal 15 and a second pedal 16 which are rotatably connected to lower end portions of each of the front connecting member 11 and the rear connecting member 12 and portions (hereinafter also referred to as "intermediate portions") located above the lower end portions, with both ends in the vehicle longitudinal direction being rotatable about rotation axes R1 to R4.

[0024] In the elevating step 10, one step is formed by the first pedal 15 rotatably connected to the lower end portion of each of the front connecting member 11 and the rear connecting member 12, and one step is formed by the second pedal 16 rotatably connected to the intermediate portion of each of the front connecting member 11 and the rear connecting member 12, and the pedals 15, 16 (the first pedal 15 and the second pedal 16) are provided in two steps as a whole, forming a two-step configuration.

[0025] In this embodiment, a plurality of pedals 15, 16 are provided. The plurality of pedals 15, 16 include a first pedal 15 with both ends rotatably connected about rotation axes R1, R2 to the lower end portion of each of the front connecting member 11 and the rear connecting member 12, and a second pedal 16 with both ends rotatably connected about rotation axes R3, R4 to the intermediate portion of each of the front connecting member 11 and the rear connecting member 12.

[0026] When viewed from the vehicle longitudinal direction, the rotation axes R1 to R4 at both ends of each of the first pedal 15 and the second pedal 16 in the vehicle longitudinal direction are arranged parallel to each other and inclined with respect to the vehicle width direction. In the present embodiment, when viewed from the vehicle longitudinal direction, the rotation axes R1 to R4 are inclined so as to be positioned downward in the vehicle vertical direction as they go toward the outside in the vehicle width direction.

[0027] In the present embodiment, at least the portions connecting the first pedal 15 and the second pedal 16 in each of the front connecting member 11 and the rear connecting member 12 are made to be elastically deformable. Each of the front connecting member 11 and the rear connecting member 12 is formed including an elastic material. For example, each of the front connecting member 11 and the rear connecting member 12 may include a laminate in which a plurality of elastic plates formed of an elastic material such as synthetic rubber or natural rubber are laminated and integrated. By each of the front connecting member 11 and the rear connecting member 12 including an elastically deformable laminate, it is difficult to be damaged even when contacting a rock or the like on the ground.

[0028] Inner seat plates 40 are provided on the inner surfaces (the surfaces facing the pedals 15, 16) of each of the front connecting member 11 and the rear connecting member 12. Outer seat plates 41 are provided on the outer surfaces (the surfaces opposite to the surfaces facing the pedals 15, 16) of each of the front connecting member 11 and the rear connecting member 12. The inner seat plates 40 and the outer seat plates 41 are fixed to each other by bolts or the like passing through the connecting members 11, 12.

[0029] In the present embodiment, the outer seat plate 41 is formed in a rectangular plate shape extending parallel to the rotation axes R1 to R4 when viewed from the vehicle longitudinal direction. The lower edges of the connecting members 11, 12 are formed along the lower edge of the outer seat plate 41 when viewed from the vehicle longitudinal direction. The lower edges of the connecting members 11, 12 are linearly inclined so as to be positioned downward in the vehicle vertical direction as they go toward the outside in the vehicle width direction when viewed from the vehicle longitudinal direction. The outer seat plate 41 is not limited to being formed in a rectangular plate shape extending parallel to the rotation axes R1 to R4 when viewed from the vehicle longitudinal direction, and may be formed in a rectangular plate shape extending parallel to the vehicle width direction.

[0030] At both ends of the first pedal 15 and the second pedal 16 in the vehicle front-rear direction, cylindrical tube portions 42 are provided. At both ends of the tube portion 42, a pair of connecting plates 43 are provided. On each inner seat plate 40, a pair of mounting pieces 44 are provided. The pair of mounting pieces 44 are arranged between the upper ends of the pair of connecting plates 43. Both ends of the first pedal 15 and the second pedal 16 in the vehicle front-rear direction are arranged between the lower ends of the pair of connecting plates 43. Both ends of the first pedal 15 and the second pedal 16 in the vehicle front-rear direction are rotatable about bolts 45 passing through the lower ends of the connecting plates 43 and the tube portion 42 as rotation axes R1 to R4. The upper ends of the connecting plates 43 may be rotatable about a bolt 46 passing through the mounting piece 44 as a rotation axis.

[0031] Both ends of the first pedal 15 and the second pedal 16 in the vehicle front-rear direction may be rotatable about a pair of bolts 45 and 46 passing through each connecting plate 43 as rotation axes with respect to the lower ends and the middle portions of the front connecting member 11 and the rear connecting member 12. When viewed in the vehicle front-rear direction, the rotation axes of the bolts 45 and 46 passing through each connecting plate 43 may be arranged parallel to each other. Thereby, the folding operation of the lifting step 10 can be performed more smoothly during the scraping-up operation.

[0032] In the example of the figure, the first pedal 15 includes, but is not limited to, three metal plates 15A having a longitudinal direction in the vehicle front-rear direction and an intermediate plate 15B connecting the intermediate portions in the longitudinal direction of each plate 15A. For example, the first pedal 15 may be configured to include two or less or four or more plates 15A, or may be configured without including the intermediate plate 15B. The configuration mode of the first pedal 15 is not limited to the above and can be changed according to the design specifications.

[0033] In the example of the figure, the second step board 16 includes, but is not limited to, three metal plates 16A having a longitudinal direction in the vehicle front-rear direction and an intermediate plate 16B that connects the intermediate portions in the longitudinal direction of each plate 16A. For example, the second step board 16 may be configured to include two or less or four or more plates 16A, or may be configured without including the intermediate plate 16B. The configuration mode of the second step board 16 is not limited to the above and can be changed according to the design specifications.

[0034] In this embodiment, let the length in the vehicle width direction of each of the first step board 15 and the second step board 16 be W, the distance in the vehicle up-down direction of the rotation axes R1 to R4 of each of the first step board 15 and the second step board 16 be H, and the minimum angle among the angles at which the rotation axes R1 to R4 incline with respect to the vehicle width direction when viewed from the vehicle front-rear direction be A. At this time, the following formulas (1) and (2) are satisfied. A = sin -1 (2W / H) / 2 ···(1) H≧2W ···(2)

[0035] Hereinafter, the length W in the vehicle width direction of each of the first step board 15 and the second step board 16 is also referred to as "step width W", the distance H in the vehicle up-down direction of the rotation axes R1 to R4 of each of the first step board 15 and the second step board 16 is also referred to as "axial distance H", and the minimum angle A among the angles at which the rotation axes R1 to R4 incline with respect to the vehicle width direction when viewed from the vehicle front-rear direction is also referred to as "axial inclination angle A". The step width W means the maximum length of the step boards 15 and 16 in the vehicle width direction (the distance between the outer end and the inner end in the vehicle width direction of the upper ends of the plates 15A and 16A of each step board 15 and 16). The axial distance H means the distance between the axial centers of each of the rotation axes R1 and R2 of the first step board 15 and the rotation axes R3 and R4 of the second step board 16 (the distance between the centers of each cylindrical portion 42). The axial inclination angle A means an acute angle at which the rotation axes R1 to R4 incline with respect to the vehicle width direction.

[0036] For example, when the step width W is 100 mm and the axial distance H is 300 mm, the axial inclination angle A is approximately 21° according to the above formulas (1) and (2). Note that the step width W, the axial distance H, and the axial inclination angle A are not limited to the above and can be changed according to the design specifications.

[0037] In this embodiment, the lifting step 10 further includes skid plates 47 that curve outward and downward in the vehicle longitudinal direction at the lower ends of each of the front connecting member 11 and the rear connecting member 12. The skid plates 47 are provided on the outer surface (the surface opposite to the surface facing the pedals 15 and 16) of the portion of the inner seat plate 40 to which the first pedal 15 is connected and that extends below each of the connecting members 11 and 12. For example, the skid plates 47 may be fixed to the outer surface of the inner seat plate 40 by welding or the like.

[0038] The skid plate 47 provided at the lower end of the front connecting member 11 has a curved portion 47A that curves in an arc shape forward and downward. The skid plate 47 provided at the lower end of the rear connecting member 12 has a curved portion 47A that curves in an arc shape rearward and downward.

[0039] In the example of the figure, the skid plates 47 are configured to include three metal plate pieces at the lower ends of the respective connecting members 11 and 12, but are not limited thereto. For example, the skid plates 47 may be configured to include two or fewer or four or more plate pieces. The configuration mode of the skid plates 47 is not limited to the above and can be changed according to the design specifications.

[0040] In this embodiment, the front connecting member 11 and the rear connecting member 12 are connected between the rear end portion 2A of the vehicle body 2 and the rear wheel 5B. A vehicle body side connecting member 50 is provided on the side surface 2C of the vehicle body 2. The upper ends of each of the front connecting member 11 and the rear connecting member 12 are rotatably attached to the connecting brackets 53 and 54 via a pair of front and rear connecting members 51 and 52. The connecting brackets 53 and 54 are fixed to the outer surface in the vehicle width direction of the vehicle body side connecting member 50 by fastening members such as bolts. A pair of connecting brackets 53 and 54 are provided at intervals in the vehicle longitudinal direction when viewed from the longitudinal direction.

[0041] Each connecting member 51, 52 is formed in a shape that bends inward in the vehicle width direction when viewed from the vehicle longitudinal direction. The lower edge portions of each connecting member 51, 52 extend along the inner surfaces of the upper end portions of each of the front connecting member 11 and the rear connecting member 12. An outer seat plate 60 is provided on the outer surface of the upper end portion of each of the front connecting member 11 and the rear connecting member 12. The lower edge portions of each connecting member 51, 52 and the outer seat plate 60 are fixed to each other by bolts or the like that penetrate each connecting member 11, 12.

[0042] The outer seat plate 60 is formed in a rectangular plate shape that extends parallel to the vehicle width direction when viewed from the vehicle longitudinal direction. The upper edges of each connecting member 11, 12 are formed along the upper edge of the outer seat plate 60 when viewed from the vehicle longitudinal direction.

[0043] The upper edge portions of each connecting member 51, 52 are rotatably attached to each connecting bracket 53, 54. A cylindrical tube portion 61 is provided on the upper edge portion of each connecting member 51, 52. A pair of attachment pieces 62 are provided on each connecting bracket 53, 54. Each attachment piece 62 extends outward and downward in the vehicle longitudinal direction from each connecting bracket 53, 54. The tube portion 61 of each connecting member 51, 52 is disposed between the lower end portions of the pair of attachment pieces 62 of each connecting bracket 53, 54.

[0044] Each connecting member 51, 52 is made rotatable with respect to the lower end portion of the attachment piece 62 using bolts 63 that penetrate the tube portion 61 and the attachment piece 62 as rotation axes R5, R6. When viewed from the vehicle longitudinal direction, each rotation axis R5, R6 is arranged parallel to each other and further parallel to the rotation axes R1 to R4, and is inclined so as to be positioned downward in the vehicle vertical direction as it goes outward in the vehicle width direction.

[0045] In the present embodiment, the front and rear connecting brackets 53, 54 are connected via a plurality of metal plate materials 65A having a longitudinal direction in the vehicle longitudinal direction. The plurality of plate materials 65A constitute the uppermost step board 65. The uppermost step board 65 is fixed to an outer seat plate 66 provided outside each connecting bracket 53, 54 by fastening members such as bolts.

[0046] In the example of the figure, the uppermost step 65 is composed of three metal plates 65A and side plates 65B that connect both longitudinal ends of each plate 65A, but is not limited thereto. For example, the uppermost step 65 may be composed of two or less or four or more plates 65A, or may be configured without the side plates 65B. The configuration mode of the uppermost step 65 is not limited to the above and can be changed according to the design specifications.

[0047] In the present embodiment, the front connecting member 11 and the rear connecting member 12 are connected to the vehicle body 2 via connecting brackets 53, 54, etc. such that the connecting portions are rotatable about the rotation axes R5, R6. When viewed from the vehicle front-rear direction, the rotation axes R5, R6 at the connecting portions of the front connecting member 11 and the rear connecting member 12 with the vehicle body 2 and the rotation axes R1 to R4 at both front-rear ends of each step 15, 16 in the vehicle front-rear direction are arranged parallel to each other and are inclined with respect to the vehicle width direction.

[0048] In addition, a stopper 69 for restricting the rotation of the lifting step 10 toward the front side of the vehicle may be provided on the cylindrical portion 61 of the front connecting member 51. The stopper abuts against the outer seat plate of the front connecting bracket 53 when the lifting step 10 attempts to rotate toward the front side of the vehicle, thereby restricting the above rotation. In the example of the figure, the stopper 69 is composed of a plate piece protruding upward from the cylindrical portion 61 of the front connecting member 51, but is not limited thereto. The configuration mode of the stopper 69 can be changed according to the design specifications.

[0049] <Explanation during scraping operation> FIG. 9 is a side view showing the lifting step 10 during the scraping operation by the wheel loader 1. FIG. 10 is a top view showing the lifting step 10 during the scraping operation. FIG. 11 is an outer view in the vehicle width direction showing the lifting step 10 during the scraping operation. Referring to FIGS. 9 to 11 together, when the wheel loader 1 equipped with the lifting step 10 of the present embodiment performs a scraping operation, the wheel loader 1 inclines at most so that the front side of the vehicle body 2 faces upward until the back-off angle defining line DL coincides with the ground GL. During the inclination in this way, the lower end of the lifting step 10 gradually approaches the ground GL, and when it exceeds a predetermined inclination, as described above, the rotation axes R1 to R4 at both ends in the vehicle longitudinal direction of each of the pedals 15 and 16 are inclined with respect to the vehicle width direction, so that they rotate at each connecting portion and escape to the outside in the vehicle width direction.

[0050] When the portion of the lifting step 10 below the connecting brackets 53 and 54 rotates to the rear side of the vehicle, it is folded between the back-off angle defining line DL and the connection positions of the front connecting member 11 and the rear connecting member 12 to the vehicle body 2. In the present embodiment, with each of the front connecting member 11, the rear connecting member 12, the first pedal 15, and the second pedal 16 rotating and the lifting step 10 being in a folded state, the first pedal 15 and the second pedal 16 are separated from each other in the vehicle width direction. In the example of FIG. 10, with the lifting step 10 in a folded state, the pedals 15 and 16 are arranged at intervals in the vehicle width direction. Note that even when each of the connecting members 11 and 12 is elastically deformed with the lifting step 10 in a folded state, the pedals 15 and 16 are arranged at intervals in the vehicle width direction.

[0051] On the other hand, when the wheel loader 1 retreats after finishing the excavation of the natural ground, the back-off angle defining line DL (that is, the lower surface of the counterweight 2B) moves away from the ground GL. Therefore, the folded state of the lifting step 10 is gradually released, and the lifting step 10 returns to its original state.

[0052] <Function and Effect> As described above, the lifting step 10 of the present embodiment is arranged at lateral positions of the vehicle body 2 with a space therebetween in the vehicle longitudinal direction, and the connecting portions with the vehicle body 2 are rotatably connected about the rotation axes R5 and R6. The front connecting member 11 and the rear connecting member 12, and both ends in the vehicle longitudinal direction of each of the lower end portions and the portions located above the lower end portions of the front connecting member 11 and the rear connecting member 12 are rotatably connected about the rotation axes R1 to R4. The first pedal 15 and the second pedal 16 are provided. When viewed from the vehicle longitudinal direction, the rotation axes R5 and R6 at the connecting portions of the front connecting member 11 and the rear connecting member 12 with the vehicle body 2 and the rotation axes R1 to R4 at both ends in the vehicle longitudinal direction of the first pedal 15 and the second pedal 16 are arranged parallel to each other and inclined with respect to the vehicle width direction. For example, in a configuration where the rotation axes at the connecting portions of the front connecting member and the rear connecting member with the vehicle body and the rotation axes at both ends in the vehicle longitudinal direction of the first pedal and the second pedal are arranged parallel to the vehicle width direction when viewed from the vehicle longitudinal direction, the upper and lower pedals may contact each other when rotating at each connecting portion during the scooping-up operation. In this case, the pedals themselves may be crushed and damaged. On the other hand, according to this configuration, when viewed from the vehicle longitudinal direction, the rotation axes R5 and R6 at the connecting portions of the front connecting member 11 and the rear connecting member 12 with the vehicle body 2 and the rotation axes R1 to R4 at both ends in the vehicle longitudinal direction of the first pedal 15 and the second pedal 16 are inclined with respect to the vehicle width direction, so that when rotating at each connecting portion during the scooping-up operation, it has a structure that escapes to one side in the vehicle width direction. Therefore, contact between the upper and lower pedals 15 and 16 can be avoided, and crushing of the pedals 15 and 16 themselves can be suppressed. Therefore, damage can be suppressed.

[0053] In the present embodiment, when viewed from the vehicle longitudinal direction, the rotation axes R1 to R4 are inclined so as to be located downward in the vehicle vertical direction as they go outward in the vehicle width direction. For example, in a configuration where the rotation axis inclines downward in the vehicle vertical direction as it faces inward in the vehicle width direction when viewed from the vehicle longitudinal direction, it becomes a structure that escapes inward in the vehicle width direction when rotating at each connection part during the scraping-up operation. Therefore, the part that escapes inward in the vehicle width direction may contact the vehicle body 2. In this case, there is a possibility of damage due to contact with the vehicle body 2. On the other hand, according to this configuration, by inclining the rotation axes R1 to R4 downward in the vehicle vertical direction as they face outward in the vehicle width direction when viewed from the vehicle longitudinal direction, it becomes a structure that escapes outward in the vehicle width direction when rotating at each connection part during the scraping-up operation. Therefore, the possibility that the part that escapes outward in the vehicle width direction contacts the vehicle body 2 is low. Thus, damage due to contact with the vehicle body 2 can be suppressed. In addition, since it is not a structure that escapes inward in the vehicle width direction, when an operator or the like raises and lowers the lifting step 10 (for example, when stepping on each pedal 15, 16), it is easy to step on each pedal 15, 16 without wobbling in the vehicle longitudinal direction.

[0054] In the present embodiment, in a state where each of the front connection member 11, the rear connection member 12, the first pedal 15, and the second pedal 16 rotates and the lifting step 10 is folded, the first pedal 15 and the second pedal 16 are separated from each other in the vehicle width direction. According to this configuration, it is possible to prevent the upper and lower pedals 15, 16 from contacting each other when rotating at each connection part during the scraping-up operation, so that damage can be more effectively suppressed.

[0055] In the present embodiment, let the length of each of the first pedal 15 and the second pedal 16 in the vehicle width direction be W, the distance in the vehicle vertical direction of the rotation axis of each of the first pedal 15 and the second pedal 16 be H, and the minimum angle among the angles at which the rotation axes R1 to R4 incline with respect to the vehicle width direction when viewed from the vehicle longitudinal direction be A. At this time, the following formulas (1) and (2) are satisfied. A = sin -1 (2W / H) / 2 ···(1) H ≧ 2W ···(2) According to this configuration, in order to satisfy the condition that the upper and lower tread plates 15 and 16 do not come into contact with each other when rotating at each connecting portion during the scraping-up operation, damage can be more effectively suppressed.

[0056] In this embodiment, at least the portions connecting the first tread plate 15 and the second tread plate 16 in each of the front connecting member 11 and the rear connecting member 12 are made elastically deformable. According to this configuration, when rotating at each connecting portion during the scraping-up operation, at least the portions connecting the first tread plate 15 and the second tread plate 16 in each of the front connecting member 11 and the rear connecting member 12 can elastically deform, so that damage can be more effectively suppressed.

[0057] In this embodiment, the elevating step 10 further includes skid plates 47 that curve outward and downward in the vehicle front-rear direction at the lower end portions of the front connecting member 11 and the rear connecting member 12, respectively. According to this configuration, since the curved portion 47A of the skid plate 47 contacts the ground GL during the scraping-up operation, damage due to contact with the ground GL can be suppressed. Also, since the lower end portion of the front connecting member 11 is not caught by the ground GL due to the skid plate 47, damage due to contact with the ground GL can be suppressed.

[0058] In this embodiment, the front connecting member 11 and the rear connecting member 12 are connected between the rear end portion 2A of the vehicle body 2 and the rear wheel 5B. The elevating step 10 is folded between the departure angle defining line DL and the connection positions of the front connecting member 11 and the rear connecting member 12 to the vehicle body 2. According to this configuration, since the elevating step 10 is folded and escapes above the departure angle defining line DL at the same level as the ground GL, damage can be more effectively suppressed.

[0059] <Second Embodiment> FIG. 12 is a perspective view of the elevating step 210 according to the second embodiment. Hereinafter, the elevating step 210 according to the second embodiment will be described with reference to FIG. 12. In the configuration shown in FIG. 12, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the detailed description thereof will be omitted.

[0060] The elevating step 210 includes a front connecting member 211 and a rear connecting member 212 that are arranged at intervals in the vehicle longitudinal direction at a side position of the vehicle body 2, lower ends and upper ends (an example of a portion located above the lower end) of each of the front connecting member 211 and the rear connecting member 212, and first pedals 215 and second pedals 216 that are rotatably connected at both ends in the vehicle longitudinal direction about rotation axes R201 to R204, front connecting members 251 and rear connecting members 252 that are arranged at intervals in the vehicle longitudinal direction above each connecting member 211, 212 and whose lower ends are rotatably connected to both ends in the vehicle longitudinal direction of the second pedal 216, and a topmost pedal 265 that is rotatably connected at both ends in the vehicle longitudinal direction to upper ends of each of the front connecting member 251 and the rear connecting member 252.

[0061] Protruding pieces 271 that protrude upward are provided at both ends in the vehicle longitudinal direction of the first pedal 215. Each protruding piece 271 has a hypotenuse that inclines so as to be located downward in the vehicle vertical direction as it goes outward in the vehicle width direction when viewed from the vehicle longitudinal direction. Annular portions 272 are provided at both ends of the hypotenuse of each protruding piece 271. Columnar shaft portions 273 are provided at the lower edge portions of each of the connecting members 211, 212. Both ends of each shaft portion 273 are supported by each annular portion 272. Both ends in the vehicle longitudinal direction of the first pedal 215 are rotatable about the shaft portions 273 supported by the annular portions 272 as rotation axes R201, R202.

[0062] At both ends of the second pedal 216 in the vehicle front-rear direction, protruding pieces 275 that protrude downward are provided. Each protruding piece 275 has a hypotenuse that inclines so as to be positioned downward in the vehicle up-down direction as it goes toward the outside in the vehicle width direction when viewed from the vehicle front-rear direction. Annular portions 276 in an annular shape are provided at both ends of the hypotenuse of each protruding piece 275. Columnar shaft portions 277 are provided at the upper edge portions of each of the connecting members 211 and 212. Both ends of each shaft portion 277 are supported by each annular portion 276. Both ends of the second pedal 216 in the vehicle front-rear direction are made rotatable with the shaft portions 277 supported by the respective annular portions 276 as rotation axes R203 and R204.

[0063] Both ends of each of the first pedal 215 and the second pedal 216 in the vehicle front-rear direction are made rotatable with the shaft portions 273 and 277 supported by the respective annular portions 272 and 276 as rotation axes R201 to R204 with respect to the lower ends and the upper ends of each of the front connecting member 211 and the rear connecting member 212. When viewed from the vehicle front-rear direction, the respective rotation axes R201 to R204 are arranged parallel to each other and incline so as to be positioned downward in the vehicle up-down direction as they go toward the outside in the vehicle width direction.

[0064] Each of the connecting members 251 and 252 is formed in a rectangular shape having a length in the vehicle up-down direction when viewed from the vehicle front-rear direction. Annular portions 281 in an annular shape are provided at positions spaced apart in the vehicle width direction at both ends of the second pedal 216 in the vehicle front-rear direction. Columnar shaft portions 282 that extend in the vehicle width direction are provided at the lower edge portions of each of the connecting members 251 and 252. Both ends of each shaft portion 282 are supported by each annular portion 281. Both ends of the second pedal 216 in the vehicle front-rear direction are made rotatable with the shaft portions 282 supported by the respective annular portions 281 as rotation axes R205 and R206.

[0065] At both ends of the uppermost pedal 265 in the vehicle front-rear direction, annular portions 285 are provided at positions spaced apart in the vehicle width direction. On the upper edge portions of the respective connecting members 251, 252, columnar shaft portions 286 extending in the vehicle width direction are provided. Both ends of each shaft portion 286 are supported by the respective annular portions 285. Both ends of the uppermost pedal 265 in the vehicle front-rear direction are rotatable about the shaft portions 286 supported by the respective annular portions 285 as rotation axes R207, R208. When viewed from the vehicle front-rear direction, the respective rotation axes R207, R208 are arranged parallel to each other with respect to the vehicle width direction.

[0066] In the present embodiment, the rotation axes R201 to R204 of the first pedal 215 and the second pedal 216 with respect to the lower end portions and the upper end portions of the front connecting member 211 and the rear connecting member 212 are arranged parallel to each other and are inclined so as to be positioned downward in the vehicle vertical direction as they go outward in the vehicle width direction. On the other hand, the rotation axes R205 to R208 of the second pedal 216 and the uppermost pedal 265 with respect to the lower end portions and the upper end portions of the front connecting member 251 and the rear connecting member 252 are arranged parallel to each other with respect to the vehicle width direction.

[0067] Also in the present embodiment, by inclining the rotation axes R201 to R204 so as to be positioned downward in the vehicle vertical direction as they go outward in the vehicle width direction when viewed from the vehicle front-rear direction, a structure is formed in which, when rotating at each connecting portion during the scraping-up operation, it escapes outward in the vehicle width direction. Therefore, the possibility that the portion that has escaped outward in the vehicle width direction contacts the vehicle body 2 is low. Accordingly, damage due to contact with the vehicle body 2 can be suppressed. In addition, since it is not a structure that escapes inward in the vehicle width direction, when an operator or the like raises and lowers the lifting step 210 (for example, when stepping on the pedal 215), it is easy to step on the pedal 215 without wobbling in the vehicle front-rear direction.

[0068] <Third Embodiment> FIG. 13 is a perspective view of the elevating step 310 according to the third embodiment. Hereinafter, the elevating step 310 according to the third embodiment will be described with reference to FIG. 13. In the configuration shown in FIG. 13, the same components as those in the above-described embodiments are denoted by the same reference numerals, and the detailed description thereof will be omitted.

[0069] The elevating step 310 includes a front connecting structure 311 and a rear connecting structure 312 that are arranged at lateral positions of the vehicle body 2 with a space therebetween in the vehicle longitudinal direction, a first pedal 215 and a second pedal 316 whose respective longitudinal ends of the lower and upper ends of each of the front connecting structure 311 and the rear connecting structure 312 are rotatably connected about rotation axes R301 to R304, a front connecting structure 351 and a rear connecting structure 352 that are arranged above each of the connecting structures 311 and 312 with a space therebetween in the vehicle longitudinal direction and whose lower ends are rotatably connected to the respective longitudinal ends of the second pedal 316 in the vehicle longitudinal direction, and a topmost pedal 365 whose respective longitudinal ends of the upper ends of each of the front connecting structure 351 and the rear connecting structure 352 are rotatably connected.

[0070] Protruding pieces 378 that protrude upward are provided at both longitudinal ends of the second pedal 316 in the vehicle longitudinal direction. Each protruding piece 378 has a hypotenuse that inclines so as to be positioned downward in the vehicle vertical direction as it goes toward the outside in the vehicle width direction when viewed from the vehicle longitudinal direction. Annular portions 379 are provided at both ends of the hypotenuse of each protruding piece 378.

[0071] Protruding pieces 388 that protrude downward are provided at both longitudinal ends of the topmost pedal 365 in the vehicle longitudinal direction. Each protruding piece 388 has a hypotenuse that inclines so as to be positioned downward in the vehicle vertical direction as it goes toward the outside in the vehicle width direction when viewed from the vehicle longitudinal direction. Annular portions 389 are provided at both ends of the hypotenuse of each protruding piece 388.

[0072] Each of the front-side connection structure 311 and the rear-side connection structure 312 includes a plurality of connection members 311A, 312A, a plurality of annular portions 311B, 312B, and a plurality of shaft portions 311C, 312C. Each of the connection members 311A, 312A has a pair of inclined sides that incline so as to be positioned downward in the vehicle vertical direction as going toward the outside in the vehicle width direction when viewed from the vehicle front-rear direction. Annular portions 311B, 312B in an annular shape are provided at both ends of one of the inclined sides of each of the connection members 311A, 312A. Cylindrical shaft portions 311C, 312C are provided on the other inclined side of each of the connection members 311A, 312A. Both ends of each of the shaft portions 311C, 312C are supported by the respective annular portions 311B, 312B.

[0073] Both ends of the first pedal 215 in the vehicle front-rear direction are rotatable about shaft portions 311C, 312C supported by the respective annular portions 272 of the respective projecting pieces 271, with the shaft portions 311C, 312C serving as rotation axes R301, R302. Both ends of the second pedal 316 in the vehicle front-rear direction are rotatable about shaft portions 311C, 312C supported by the respective annular portions 276 of the respective projecting pieces 275, with the shaft portions 311C, 312C serving as rotation axes R303, R304. Further, the connection portions in each of the connection structures 311, 312 are rotatable about shaft portions 311C, 312C supported by the respective annular portions 311B, 312B of the respective connection members 311A, 312A, with the shaft portions 311C, 312C serving as rotation axes R305 to R308. When viewed from the vehicle front-rear direction, the respective rotation axes R301 to R308 are arranged parallel to each other and incline so as to be positioned downward in the vehicle vertical direction as going toward the outside in the vehicle width direction.

[0074] Each of the front connection structure 351 and the rear connection structure 352 includes a plurality of connection members 351A, 352A, a plurality of annular portions 351B, 352B, and a plurality of shaft portions 351C, 352C. Each of the connection members 351A, 352A has a pair of hypotenuses that incline so as to be positioned downward in the vehicle vertical direction as going outward in the vehicle width direction when viewed from the vehicle front-rear direction. Annular portions 351B, 352B in an annular shape are provided at both ends of one hypotenuse of each of the connection members 351A, 352A. Columnar shaft portions 351C, 352C are provided on the other hypotenuse of each of the connection members 351A, 352A. Both ends of each of the shaft portions 351C, 352C are supported by the respective annular portions 351B, 352B.

[0075] Both ends of the second pedal 316 in the vehicle front-rear direction are rotatable about shaft portions 351C, 352C supported by the respective annular portions 379 of the respective protruding pieces 378, with the shaft portions 351C, 352C serving as rotation axes R309, R310. Both ends of the uppermost pedal 365 in the vehicle front-rear direction are rotatable about shaft portions 351C, 352C supported by the respective annular portions 389 of the respective protruding pieces 388, with the shaft portions 351C, 352C serving as rotation axes R311, R312. Further, the connecting portions in each of the connection structures 351, 352 are rotatable about shaft portions 351C, 352C supported by the respective annular portions 351B, 352B of the respective connection members 351A, 352A, with the shaft portions 351C, 352C serving as rotation axes R313 to R316. When viewed from the vehicle front-rear direction, the respective rotation axes R309 to R316 are arranged parallel to each other and incline so as to be positioned downward in the vehicle vertical direction as going outward in the vehicle width direction.

[0076] In the present embodiment, the rotation axes R301 to R304 of each of the first pedal 215 and the second pedal 316 with respect to the lower end portions and the upper end portions of each of the front connection structure 311 and the rear connection structure 312 are arranged parallel to each other and incline so as to be positioned downward in the vehicle vertical direction as going outward in the vehicle width direction. Similarly, the rotation axes R309 to R312 of each of the second pedal 316 and the uppermost pedal 365 with respect to the lower end portions and the upper end portions of each of the front connection structure 351 and the rear connection structure 352 are also arranged parallel to each other and incline so as to be positioned downward in the vehicle vertical direction as going outward in the vehicle width direction.

[0077] Also in this embodiment, by inclining the rotation axes R301 to R304 so as to be positioned downward in the vehicle vertical direction as they go outward in the vehicle width direction when viewed from the vehicle front-rear direction, a structure is formed such that when rotating at each connection part during the scraping-up operation, it escapes outward in the vehicle width direction. Therefore, the possibility that the portion that has escaped outward in the vehicle width direction comes into contact with the vehicle body 2 is low. Thus, damage due to contact with the vehicle body 2 can be suppressed. In addition, since it is not a structure that escapes inward in the vehicle width direction, when an operator or the like raises and lowers the lifting step 310 (for example, when stepping on each pedal 215, 316), it is easy to step on each pedal 215, 316 without wobbling in the vehicle front-rear direction.

[0078] <Fourth Embodiment> FIG. 14 is a perspective view of the lifting step 410 according to the fourth embodiment. Hereinafter, the lifting step 410 according to the fourth embodiment will be described with reference to FIG. 14. In the configuration shown in FIG. 14, the same components as those in the above-described embodiments are denoted by the same reference numerals, and the detailed description thereof is omitted.

[0079] The lifting step 410 includes a front connection member 211 and a rear connection member 212 that are arranged at intervals in the vehicle front-rear direction at a side position of the vehicle body 2, a first pedal 215 and a second pedal 316 that are rotatably connected to both ends in the vehicle front-rear direction of each of the lower end portions and the upper end portions of the front connection member 211 and the rear connection member 212 about rotation axes R401 to R404, a front connection member 451 and a rear connection member 452 that are arranged at intervals in the vehicle front-rear direction above each connection member 211, 212 and whose lower ends are rotatably connected to both ends in the vehicle front-rear direction of the second pedal 316, and a topmost pedal 365 whose both ends in the vehicle front-rear direction are rotatably connected to the upper end portions of the front connection member 451 and the rear connection member 452.

[0080] At the lower edge portions of the connection members 451 and 452, cylindrical shaft portions 482 are provided. Both ends of each shaft portion 482 are supported by the annular portions 379 of the respective projecting pieces 378. Both ends of the second tread plate 316 in the vehicle longitudinal direction are rotatable about the shaft portions 482 supported by the annular portions 379 as rotation axes R405 and R406.

[0081] At the upper edge portions of the connection members 451 and 452, cylindrical shaft portions 486 are provided. Both ends of each shaft portion 486 are supported by the annular portions 389 of the respective projecting pieces 388. Both ends of the uppermost tread plate 365 in the vehicle longitudinal direction are rotatable about the shaft portions 486 supported by the annular portions 389 as rotation axes R407 and R408.

[0082] In the present embodiment, the rotation axes R401 and R404 of the first tread plate 215 and the second tread plate 316 with respect to the lower end portions and the upper end portions of the front connection member 211 and the rear connection member 212 are arranged parallel to each other and are inclined so as to be positioned downward in the vehicle vertical direction as going toward the outside in the vehicle width direction. Similarly, the rotation axes R405 to R408 of the second tread plate 316 and the uppermost tread plate 365 with respect to the lower end portions and the upper end portions of the front connection member 451 and the rear connection member 452 are also arranged parallel to each other and are inclined so as to be positioned downward in the vehicle vertical direction as going toward the outside in the vehicle width direction.

[0083] Also in the present embodiment, by inclining the rotation axes R401 to R404 so as to be positioned downward in the vehicle vertical direction as going toward the outside in the vehicle width direction when viewed from the vehicle longitudinal direction, it becomes a structure that escapes to the outside in the vehicle width direction when rotating at each connection portion during the scraping-up operation. Therefore, the possibility that the portion that has escaped to the outside in the vehicle width direction comes into contact with the vehicle body 2 is low. Accordingly, damage due to contact with the vehicle body 2 can be suppressed. In addition, since it is not a structure that escapes to the inside in the vehicle width direction, it is easy to step on the tread plates 215 and 316 without wobbling in the vehicle longitudinal direction when an operator or the like raises and lowers the lifting step 410 (for example, when stepping on each tread plate 215 and 316).

[0084] <Modification Example> In the above-described embodiments, an example has been described in which a plurality of tread plates are provided, and the plurality of tread plates include a first tread plate whose both ends are rotatably connected to the lower end portions of each of the front connecting member and the rear connecting member about a rotation axis, and a second tread plate whose both ends are rotatably connected to portions located above the lower end portions of each of the front connecting member and the rear connecting member about a rotation axis. However, the present invention is not limited to this. For example, only one tread plate may be provided. The installation mode of the tread plate can be changed according to the design specifications.

[0085] In the above-described embodiments, an example has been described in which, when viewed from the vehicle front-rear direction, the rotation axis is inclined so as to be located downward in the vehicle vertical direction as it goes toward the outside in the vehicle width direction. However, the present invention is not limited to this. For example, when viewed from the vehicle front-rear direction, the rotation axis may be inclined so as to be located downward in the vehicle vertical direction as it goes toward the inside in the vehicle width direction. The mode in which the rotation axis is inclined when viewed from the vehicle front-rear direction can be changed according to the design specifications.

[0086] In the above-described embodiments, an example has been described in which, in a state where the front connecting member, the rear connecting member, the first tread plate, and the second tread plate each rotate and the elevating step is folded, the first tread plate and the second tread plate are separated from each other in the vehicle width direction. However, the present invention is not limited to this. For example, in a state where the elevating step is folded, the first tread plate and the second tread plate may be in contact with each other in the vehicle width direction only at a part of each. The mode in which the first tread plate and the second tread plate are separated from each other in a state where the elevating step is folded can be changed according to the design specifications.

[0087] In the above-described embodiments, when the length of each of the first tread plate and the second tread plate in the vehicle width direction is W, the distance in the vehicle vertical direction between the rotation axes of each of the first tread plate and the second tread plate is H, and the minimum angle among the angles at which the rotation axis is inclined with respect to the vehicle width direction when viewed from the vehicle front-rear direction is A, an example has been described in which the following formulas (1) and (2) are satisfied. However, the present invention is not limited to this. A = sin -1 (2W / H) / 2 ···(1) H ≧ 2W ···(2) For example, it is not necessary to satisfy the above formulas (1) and (2). The values of W, H, and A can be changed according to the design specifications.

[0088] In the above-described embodiments, an example has been described in which at least the portions connecting the first tread plate and the second tread plate in each of the front connecting member and the rear connecting member are elastically deformable, but the present invention is not limited thereto. For example, each of the front connecting member and the rear connecting member may be composed only of a rigid member (for example, a metal material). For example, the elastically deformable member may be configured to include a single rubber plate material, or may be configured to include a composite member of a rubber plate material and a soft metal plate such as lead. The configuration mode of each of the front connecting member and the rear connecting member can be changed according to the design specifications.

[0089] In the above-described embodiments, an example has been described in which the elevating step further includes a skid plate that curves outward and downward in the vehicle front-rear direction at the lower end of each of the front connecting member and the rear connecting member, but the present invention is not limited thereto. For example, the skid plate may not curve outward and downward in the vehicle front-rear direction. For example, the elevating step may not further include a skid plate. The mode of the skid plate can be changed according to the design specifications.

[0090] In the above-described embodiments, an example has been described in which the front connecting member and the rear connecting member are connected between the end of the vehicle body and the wheel, and the elevating step is folded between the back-off angle defining line connecting the lower rear part of the vehicle body and the wheel and the connection positions of the front connecting member and the rear connecting member to the vehicle body, but the present invention is not limited thereto. For example, the front connecting member and the rear connecting member may not be connected between the end of the vehicle body and the wheel. For example, the elevating step may be folded outside the back-off angle defining line connecting the lower rear part of the vehicle body and the wheel and the connection positions of the front connecting member and the rear connecting member to the vehicle body. The connection mode of the front connecting member and the rear connecting member, and the mode in which the elevating step is folded can be changed according to the design specifications.

[0091] In the above-described embodiments, the lifting step was described by taking as an example the case where it is provided between the rear end of the vehicle body and the rear wheels, but it is not limited to this. For example, depending on the work vehicle other than the wheel loader, the lifting step may be provided between the front end of the vehicle body and the front wheels. The installation mode of the lifting step can be changed according to the design specifications.

[0092] In the above-described embodiments, the lifting step was described by taking as an example the case where it has a two-step configuration including the first tread board and the second tread board, but it is not limited to this. For example, the lifting step may have a configuration including a plurality of tread boards with three or more steps. The configuration mode of the lifting step can be changed according to the design specifications.

[0093] In the above-described embodiments, the front connecting member and the rear connecting member were described by taking as an example the case where the connecting portion with the vehicle body via a connecting bracket or the like is rotatably connected about the rotation axis, but it is not limited to this. For example, the front connecting member and the rear connecting member may be rotatably connected about the rotation axis with the connecting portion with the vehicle body without using a connecting bracket or the like. For example, the front connecting member and the rear connecting member may be directly or indirectly rotatably connected about the rotation axis with the connecting portion with the vehicle body. The connection mode of the front connecting member and the rear connecting member to the vehicle body can be changed according to the design specifications.

[0094] In the above-described embodiments, the wheel loader was described as an example of the work vehicle equipped with the lifting step, but it is not limited to this. For example, the lifting step may be applied to work vehicles such as off-road dump trucks. The application target of the lifting step can be changed according to the design specifications.

[0095] As described above, the embodiments of the present invention have been described, but the present invention is not limited thereto, and additions, omissions, substitutions, and other changes of the configuration are possible without departing from the spirit of the present invention, and it is also possible to appropriately combine the above-described embodiments.

[0096] (Appendix 1) A front connecting member and a rear connecting member that are arranged at intervals in the vehicle front-rear direction at a side position of the vehicle body, and the connecting portions with the vehicle body are rotatably connected around a rotation axis, and a tread plate in which both end portions in the vehicle front-rear direction are rotatably connected around a rotation axis to a lower end portion of each of the front connecting member and the rear connecting member or a portion located above the lower end portion, when viewed from the vehicle front-rear direction, the rotation axis at the connecting portion of each of the front connecting member and the rear connecting member with the vehicle body and the rotation axis at both end portions of the tread plate are arranged parallel to each other and inclined with respect to the vehicle width direction, a lifting step of a work vehicle.

[0097] (Appendix 2) a plurality of the tread plates are provided, the plurality of tread plates, a first tread plate in which both end portions are rotatably connected around the rotation axis to the lower end portion of each of the front connecting member and the rear connecting member, and a second tread plate in which both end portions are rotatably connected around the rotation axis to a portion located above each of the front connecting member and the rear connecting member, a lifting step of the work vehicle according to Appendix 1.

[0098] (Appendix 3) when viewed from the vehicle front-rear direction, the rotation axis is inclined so as to be located downward in the vehicle vertical direction as it goes toward the outside in the vehicle width direction, a lifting step of the work vehicle according to Appendix 1 or 2.

[0099] (Appendix 4) in a state where the front connecting member, the rear connecting member, the first tread plate, and the second tread plate each rotate and the lifting step is folded, the first tread plate and the second tread plate are separated from each other in the vehicle width direction, a lifting step of the work vehicle according to Appendix 2.

[0100] (Appendix 5) When the vehicle-width direction length of each of the first pedal and the second pedal is W, the distance in the vehicle up-and-down direction of the rotation axis of each of the first pedal and the second pedal is H, and the minimum angle among the angles at which the rotation axis inclines with respect to the vehicle-width direction as viewed from the vehicle front-rear direction is A, the following formulas (1) and (2) are satisfied: A = sin -1 (2W / H) / 2 ···(1) H ≥ 2W ···(2) The lifting step of the work vehicle according to Appendix 2 or 4.

[0101] (Appendix 6) In each of the front-side connecting member and the rear-side connecting member, at least the portion connecting the first pedal and the second pedal is made to be elastically deformable. The lifting step of the work vehicle according to Appendix 2, 4 or 5.

[0102] (Appendix 7) Each of the lower end portions of the front-side connecting member and the rear-side connecting member is further provided with a skid plate that curves outward and downward in the vehicle front-rear direction. The lifting step of the work vehicle according to any one of Appendices 1 to 6.

[0103] (Appendix 8) The front-side connecting member and the rear-side connecting member are connected between the end portion of the vehicle body and the wheel. The lifting step is folded between the departure angle defining line connecting the lower rear portion of the vehicle body and the wheel and the connection positions of the front-side connecting member and the rear-side connecting member to the vehicle body. The lifting step of the work vehicle according to any one of Appendices 1 to 7.

Explanation of Signs

[0104] 1... Wheel loader (work vehicle), 2... Vehicle body, 2A... Rear end (end of the vehicle body), 5B... Rear wheel (wheel), 10... Lifting step, 11... Front connecting member, 12... Rear connecting member, 15... First pedal, 16... Second pedal, 47... Skid plate, 210... Lifting step, 211... Front connecting member, 212... Rear connecting member, 215... First pedal, 216... Second pedal, 310... Lifting step, 311... Front connecting member, 312... Rear connecting member, 410... Lifting step, DL... Departure angle defining line, R1, R2, R3, R4... Rotation axis

Claims

1. A front connecting member and a rear connecting member that are arranged at intervals in the vehicle longitudinal direction at a side position of the vehicle body and whose connecting portions with the vehicle body are rotatably connected about a rotation axis, and at least one pedal whose both end portions in the vehicle longitudinal direction are rotatably connected about a rotation axis to each of the lower end portions of the front connecting member and the rear connecting member or portions located above the lower end portions, and when viewed from the vehicle longitudinal direction, the rotation axes at the connecting portions of the front connecting member and the rear connecting member with the vehicle body and the rotation axes at both end portions of the pedal are arranged parallel to each other and inclined with respect to the vehicle width direction, a lifting step of a work vehicle.

2. A plurality of the pedals are provided, The plurality of pedals, a first pedal whose both end portions are rotatably connected about the rotation axis to each of the lower end portions of the front connecting member and the rear connecting member, and a second pedal whose both end portions are rotatably connected about the rotation axis to portions located above each of the front connecting member and the rear connecting member, and The lifting step of the work vehicle according to Claim 1.

3. When viewed from the vehicle longitudinal direction, the rotation axis is inclined so as to be located downward in the vehicle vertical direction as it goes toward the outside in the vehicle width direction, The lifting step of the work vehicle according to Claim 1 or 2.

4. In a state where the front connecting member, the rear connecting member, the first pedal, and the second pedal each rotate and the lifting step is folded, the first pedal and the second pedal are separated from each other in the vehicle width direction, The lifting step of the work vehicle according to Claim 2.

5. When the length of each of the first pedal and the second pedal in the vehicle width direction is W, the distance in the vehicle vertical direction of the rotation axis of each of the first pedal and the second pedal is H, and the minimum angle among the angles at which the rotation axis is inclined with respect to the vehicle width direction when viewed from the vehicle longitudinal direction is A, the following formulas (1) and (2) are satisfied, A = sin －１ (2W / H) / 2...(1) H≧2W...(2) The lifting step of the work vehicle according to Claim 2 or 4.

6. In each of the front connecting member and the rear connecting member, at least the portions connecting the first pedal and the second pedal are made elastically deformable, The lifting step of the work vehicle according to Claim 2 or 4.

7. The lower end portions of each of the front connecting member and the rear connecting member are further provided with skid plates that curve outward and downward in the longitudinal direction of the vehicle. The lifting step of the work vehicle according to claim 1 or 2.

8. The front connecting member and the rear connecting member are connected between an end portion of the vehicle body and a wheel. The lifting step is folded between a line defining a departure angle connecting a lower rear portion of the vehicle body and a wheel, and a connection position of the front connecting member and the rear connecting member to the vehicle body. The lifting step of the work vehicle according to claim 1 or 2.

Images