Ladder device for work vehicle

Abstract

To provide a ladder device for work vehicle that can reduce cost of manufacture with simple structure, and can achieve a high level of both damage prevention and ease of entry and exit.SOLUTION: A ladder 10, in which a plurality of steps 10b are arranged between a pair of left and right stringers 10a having flexibility, is hung from a platform 9 of a vehicle body 2, and is made so that users can get on and off by placing their feet on a front side of the ladder 10 in order. A frame-like support member 18 is provided on a rear side of the ladder 10, and the ladder is guided in a vertical direction by a pair of left and right guide pipes 19 provided on the platform 9. At a lower position of the support member 18, each step 10b of the ladder 10 is brought into contact with the support member 18 to suppress deflection to a depth side, and at an upper position thereof, deflection of the ladder 10 to the depth side is permitted.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a ladder device for a work vehicle. [Background technology]

[0002] For example, work vehicles such as dump trucks used in mines are equipped with large-diameter tires to ensure smooth travel on rough terrain and prevent interference between the vehicle body and the ground. This increases the vehicle's minimum ground clearance, making it difficult for operators to get on and off the vehicle. To prevent this, a ladder is attached to the bottom of the vehicle, extending from the ground to the ground. For example, the ladder is made by welding steel plates or the like, and has multiple steps arranged vertically between a pair of side beams. However, such ladders can collide with obstacles such as rocks scattered on the ground while the work vehicle is traveling, or with the ground due to the vehicle's up and down movement as it travels, resulting in damage.

[0003] As a conventional technique for addressing this issue, a ladder 10 has been put to practical use, in which left and right side girders 10a (only one of which is shown) connecting each step 10b are made of a flexible material such as rubber, as shown in Figure 16. Figure 11(c) shows a ladder device 11 according to an embodiment, and the ladder 10 has the same configuration, so the description will be based on this figure. For example, when the ladder 10 collides with an obstacle such as a rock on the ground, the side girders 10a of the ladder 10 bend backward to prevent damage. However, as shown in Figure 16, when an operator steps on the step 10b of the ladder 10 to get on or off, the side girders 10a and ultimately the entire ladder 10 bend backward under the weight of the operator, causing another problem in that it makes it difficult to get on or off.

[0004] Therefore, in order to achieve both the above-mentioned damage prevention and ease of getting on and off, a ladder has been proposed, as described in Patent Document 1, for example. In this ladder, left and right side beams are formed by vertically spaced and connected multiple block bodies with U-shaped claws, which gives the side beams flexibility and prevents damage to the ladder while in motion. Furthermore, when an operator's weight acts on the ladder when getting on or off, the claws of the upper and lower block bodies interlock with each other, restricting the bending of the side beams, thereby increasing the rigidity of the ladder and ensuring good ease of getting on and off. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 3-122939 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the ladder in Patent Document 1 has a problem in that the left and right side beams are made up of a large number of complexly shaped block bodies connected together, which makes the structure complicated and increases manufacturing costs. In addition, because the block bodies have a complex shape, the engagement of the claws can be uncertain. For example, if some of the claws remain engaged even when the operator's weight is not acting, the side beams may not bend sufficiently and may be damaged when the ladder collides with an obstacle while traveling.

[0007] The present invention has been made to solve these problems, and its purpose is to provide a ladder device for a work vehicle that has a simple structure that reduces manufacturing costs and achieves a high level of both damage prevention and ease of boarding and disembarking. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the ladder device for a work vehicle of the present invention comprises a ladder consisting of a pair of flexible side girders with multiple steps arranged vertically between them, suspended from a platform attached to the vehicle body, and allowing passengers to board and disembark between the platform and the ground from the front side of the ladder via the multiple steps.The ladder device for a work vehicle is characterized in that it is provided with a support member that moves vertically through the platform at the rear side of the ladder, and at a lower position, abuts against the multiple steps from the rear side to restrict bending of the ladder toward the rear, and at an upper position, allows bending of the ladder toward the rear. [Effects of the Invention]

[0009] According to the ladder device for a work vehicle of the present invention, the manufacturing cost can be reduced by the simple structure, and it is possible to achieve both damage prevention and ease of getting on and off at a high level. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view showing a dump truck to which a ladder device according to an embodiment is applied. [Figure 2] FIG. 1 is a front view showing a dump truck. [Figure 3] 10 is a perspective view showing the main ladder device when the support member is switched to the lower position. FIG. [Figure 4] A front view showing the main ladder device when the support member is switched to the lower position. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 4. [Figure 7] FIG. [Figure 8] 10 is a perspective view showing the main ladder device when the support member is switched to the upper position. FIG. [Figure 9] A front view showing the main ladder device when the support member is switched to the upper position. [Figure 10] 10 is a cross-sectional view taken along line XX in FIG. 9. [Figure 11] FIG. 10 is an explanatory diagram showing the sequence of operations when an operator gets on and off between the ground and the vehicle body via a ladder. [Figure 12] FIG. 2 is a side view corresponding to FIG. 1, showing another example in which a ladder device is provided on the left side of the vehicle body. [Figure 13] FIG. 7 is a cross-sectional view corresponding to FIG. 6, showing another example in which a pair of left and right notched surfaces are formed at the rear end of each step. [Figure 14] FIG. 7 is a cross-sectional view corresponding to FIG. 6, showing another example in which two pairs of left and right notched surfaces are formed at the rear end of each step. [Figure 15] 5A and 5B are cross-sectional views showing another example in which wires are used as stringers. [Figure 16] FIG. 1 is an explanatory diagram showing a state in which a conventional ladder bends backward under the weight of an operator, making it difficult to get on and off. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described, in which the present invention is embodied in a ladder device for an extra-large dump truck that operates in mines or the like. Fig. 1 is a side view of a dump truck to which the ladder device of this embodiment is applied, and Fig. 2 is a front view of the dump truck. The dump truck 1 is used to transport excavated materials such as crushed stone and earth and sand excavated in mines, etc. In the following description, the front-rear, left-right, and up-down directions are expressed from the perspective of an operator riding in the dump truck 1.

[0012] A body 2 of the dump truck 1 is provided with a pair of left and right front tires 3f and two pairs of left and right rear tires 3r, and these tires 3f, 3r are used to drive the dump truck 1. A loading platform 4 for loading excavated materials is disposed at the rear of the body 2, and the loading platform 4 tilts rearward in response to the extension of a hoist cylinder (not shown), allowing the loaded excavated materials to be discharged.

[0013] An engine space 5 is provided in the front of the vehicle body 2, and an engine (not shown) and auxiliary equipment such as a radiator for cooling the engine and a battery are mounted therein. The engine drives a generator, and the generated power is supplied to a traction motor (not shown), which drives and rotates rear tires 3r, causing the dump truck 1 to travel.

[0014] A flat deck 6 is formed directly above the engine space 5 on the vehicle body 2, and a driver's cab 7 in which an operator who drives the dump truck 1 boards is provided on the left side of the deck 6. A staircase 8 is provided at the front of the vehicle body 2, slanting diagonally downward to the left, and the upper end of the staircase 8 is connected to the deck 6. The lower end of the staircase 8 extends to the bottom of the vehicle body 2 and is connected to a flat platform 9 that functions as a standing position for the operator and workers who perform maintenance (hereinafter collectively referred to as the operator).

[0015] The front and rear tires 3f, 3r have large diameters to ensure travelability on rough terrain and to prevent interference between the vehicle body and the ground, and as a result, the position of the platform 9 is also raised along with the vehicle body 2. Therefore, a ladder 10 is provided on the platform 9 in consideration of ease of getting on and off the vehicle body 2, and details of the main ladder device 11, including this ladder 10, will be described below. In addition to the main ladder device 11, the front of the vehicle body 2 is provided with a maintenance ladder device 12 used when performing maintenance on the battery in the engine space 5, and an escape ladder device 13 for the operator to evacuate to the ground in the event of an emergency such as a vehicle fire, but these ladder devices 12, 13 have the same configuration as the main ladder device 11, so duplicated explanations will be omitted.

[0016] Figure 3 is an oblique view showing the main ladder device 11 when the support member is switched to the lower position, Figure 4 is a front view showing the main ladder device 11 when the support member is switched to the lower position, Figure 5 is a cross-sectional view taken along line VV in Figure 4, and Figure 6 is a cross-sectional view taken along line VI-VI in Figure 4. Overall, the platform 9 has a box-like shape made of welded steel plates. Specifically, the platform 9 is composed of an upper plate 9a that is rectangular in plan view, a front plate 9b, a left plate 9c, a right plate 9d, and a rear plate 9e that surround the upper plate 9a, and a lower plate 9g that is disposed below the front of the upper plate 9a and is connected to the platform 9 via the front plate 9b, the left plate 9c, the right plate 9d, and a middle plate 9f.

[0017] Handrails 15 are provided on the right and rear sides of the platform 9, and a handrail 16 is also provided on the stairs 8. A pair of left and right grips 17 that the operator holds when getting on and off the ladder 10 are provided on the front sides of the handrails 15 and 16, extending in the vertical direction.

[0018] A ladder 10 extends from the platform 9 toward the ground. The ladder 10 consists of a pair of flexible side girders 10a made of rubber or the like, and three grating steps 10b arranged in parallel in the vertical direction and connecting the left and right side girders 10a. The upper ends of the left and right side girders 10a are connected to the underside of the bottom plate 9g of the platform 9, and the lower ends are spaced from the ground so that an operator standing on the ground can place their feet on them.

[0019] The above configuration is similar to that of a dump truck of the prior art. As described with reference to FIG. 11(c), when the ladder collides with an obstacle such as a rock on the ground, the side girders 10a of the ladder bend backward to prevent damage. The operator can get on and off the ladder 10 between the ground and the platform 9 by stepping on each step 10b from the front side of the ladder 10 (corresponding to the "front side of the ladder" in this invention). For example, an operator on the ground can climb the ladder 10 to the platform 9 and then access the cab 7 on the deck 6 via the stairs 8, or can descend from the cab 7 to the ground by following the reverse route. However, as described with reference to FIG. 16, when getting on and off the ladder 10, the side girders 10a, and ultimately the entire ladder 10, bend backward under the weight of the operator, resulting in a problem of poor ease of getting on and off.

[0020] In consideration of these problems, in this embodiment, a support member 18 is arranged on the rear side of the ladder 10 (corresponding to the ``rear side of the ladder'' in the present invention) to take measures to prevent the ladder 10 from bending backward, and the configuration thereof is described below.

[0021] In this embodiment, a pair of left and right guide pipes 19 extending in the vertical direction are arranged between the upper plate 9a and the lower plate 9g of the platform 9. The upper end of each guide pipe 19 is welded while passing through the upper plate 9a, and the lower end is welded while passing through the lower plate 9g, so that the interior of each guide pipe 19 is open upward and downward via the upper plate 9a and the lower plate 9g. In the horizontal direction, each guide pipe 19 is located slightly inside the left and right stringers 10a of the ladder 10, and these guide pipes 19 function to guide the support member 18 in the vertical direction.

[0022] In this embodiment, the support member 18 as a whole has a frame shape made of welded steel pipes (corresponding to the "pipe material" of the present invention). More specifically, the support member 18 comprises a main body portion 18a having a generally U-shape that is long in the vertical direction, a horizontal connecting portion 18b connecting the left and right upper ends of the main body portion 18a to each other, and a locked portion 18c formed by extending the horizontal connecting portion 18b to the right. In the following description, a pair of left and right linear portions extending in the vertical direction of the main body portion 18a are referred to as sliding contact portions 18d, and these sliding contact portions 18d are inserted into each guide pipe 19 so as to be slidable in the vertical direction. As a result, the support member 18 is assembled to the platform 9, and the entire support member 18 is guided in the vertical direction while the sliding contact portions 18d slide within each guide pipe 19.

[0023] The support member 18, which is a frame made of steel pipe, has enough rigidity to restrict the bending of the ladder 10, and is inexpensive due to its simple shape. It is also light enough that its weight can be easily supported by hand. This allows an operator on the platform 9 to easily lift the support member 18 from a lower position, as will be described later.

[0024] When the support member 18 moves downward due to its own weight, its horizontal connecting portion 18b abuts on the upper plate 9a of the platform 9, restricting its movement, as shown in Figures 3 to 5. Hereinafter, this position will be referred to as the "lower position." At this time, the support member 18 is disposed correspondingly on the rear side of the ladder 10 in the vertical direction, with its left and right sliding contact portions 18d positioned on the rear side of each step 10b. At this time, the sliding contact portions 18d may be in contact with the steps 10b or may be slightly spaced apart.

[0025] As shown in Figure 6, a pair of left and right anti-lateral displacement brackets 21l, 21r (corresponding to the "anti-lateral displacement portion" of the present invention) are welded to the rear end of each step 10b of the ladder 10, corresponding to the support member 18 at the lower position. More specifically, the anti-lateral displacement brackets 21l, 21r are disposed on both sides of the left and right sliding contact portions 18d of the support member 18, with one side protruding rearward. Therefore, when the ladder 10 begins to bend left or right, the anti-lateral displacement brackets 21l, 21r abut against the sliding contact portions 18d of the support member 18, thereby restricting the ladder 10 from bending left or right. In addition, since the anti-lateral displacement brackets 21l, 21r are provided on all steps 10b and each of the anti-lateral displacement brackets 21l, 21r abuts against the sliding contact portions 18d, twisting of the ladder 10 is also restricted.

[0026] Figure 7 is an oblique view showing the locking device, Figure 8 is an oblique view showing the main ladder device 11 when the support member 18 is switched to the upper position, Figure 9 is a front view showing the main ladder device 11 when the support member 18 is switched to the upper position, and Figure 10 is a cross-sectional view along line XX in Figure 9. As shown in Figures 7 and 8, a locking device 22 is provided on the upper right side of the handrail 15 on the platform 9. The locking device 22 is welded to the handrail 15 and consists of a lock bracket 23 with a stepped horizontal holding portion 23a formed at the bottom, and a lock bar 24 rotatably connected to a shaft 23b erected on the lock bracket 23. The downward rotation of the lock bar 24 due to its own weight is restricted by the horizontal holding portion 23a, so that the lock bar 24 is maintained in a horizontal position and can rotate from this horizontal position to a position with its tip facing upward.

[0027] The tip of the locking bar 24 in the horizontal position is located directly above the locked portion 18c of the support member 18. Therefore, when the operator pulls the support member 18 from the lower position upward, the support member 18 moves upward while being guided by the guide pipe 19 and protrudes upward from the platform 9. The locked portion 18c of the support member 18 pushes up and rotates the locking bar 24, and after passing the locked portion 18c, the locking bar 24 returns to the horizontal position due to its own weight. When the operator stops pulling up, the support member 18 moves downward due to its own weight, but because the locked portion 18c is engaged with the locking bar 24, further downward movement is restricted, as shown in Figures 8 to 10. Hereinafter, this position will be referred to as the upper position. At this time, the support member 18 retracts upward from the lower position, in other words, from the rear side of the ladder 10, thereby opening the rear side of the ladder 10 and allowing it to bend backward.

[0028] From this state, when an operator standing on the platform 9 lifts the horizontal connecting portion 18b of the support member 18 and releases the lock bar 24, the support member 18 moves downward due to its own weight and is returned to the lower position again.

[0029] Next, the effects of the main ladder device 11 configured as above will be described. FIG. 11 is an explanatory diagram showing the sequence of operations when an operator gets on and off the ladder 10 between the ground and the vehicle body. When the dump truck 1 is parked after work is completed, the support member 18 of the main ladder device 11 is switched to the lower position. When the operator starts the next work, he climbs the ladder 10 from the ground to get into the cab 7 of the dump truck 1, and at that time, the operator's weight acts to bend the ladder 10 backward.

[0030] However, since the support member 18 is disposed on the rear side of the ladder 10, the left and right sliding contact portions 18d thereof come into contact with each step 10b of the ladder 10, restricting rearward displacement. Therefore, as shown in Figures 5 and 11(a), the backward bending of the ladder 10 is restricted, and the operator can easily climb up to the platform 9 via the ladder 10.

[0031] Furthermore, when an operator climbs the ladder 10, the ladder 10 may bend or twist left and right due to the operator's shifting of weight from side to side. However, the lateral displacement prevention brackets 21l and 21r of each step 10b abut against the sliding contact portion 18d of the support member 18, thereby restricting the ladder 10 from bending or twisting left and right. This factor also contributes to making it easier for the operator to climb the ladder 10.

[0032] 11(b), when the operator grasps the horizontal connecting portion 18b of the support member 18 and pulls it up after it has reached the platform 9, its locked portion 18c is hooked onto the lock bar 24 of the locking device 22. This keeps the support member 18 in an upper position, and the rear side of the ladder 10 is released, allowing it to bend backward. Therefore, when the dump truck 1 is traveling and has started work, as shown in FIG. 11(c), if the ladder 10 collides with an obstacle such as a rock on the ground, its side girder 10a will bend backward, reliably preventing damage.

[0033] When the work is completed, the operator descends from the cab 7 via the stairs 8 to the platform 9, and releases the lock bar 24 while lifting the horizontal connector 18b of the support member 18. As shown in Figure 11(d), the support member 18 moves downward by its own weight and returns to the lower position. Therefore, as shown in Figure 11(e), the bending and twisting of the ladder 10 in the rearward and left-right directions are again restricted by the support member 18, so the operator can easily descend to the ground via the ladder 10.

[0034] As described above, the main ladder device 11 of this embodiment reliably prevents damage to the ladder 10 due to collision with obstacles such as rocks on the ground while the dump truck 1 is traveling, and similarly prevents damage due to collision with the ground caused by the vertical movement of the vehicle body. Furthermore, when getting on or off the ladder 10, the support members 18 restrict bending or twisting of the ladder 10 in the rearward or left-right directions, making it easy to get on or off. As a result, it is possible to achieve both high levels of prevention of damage to the ladder 10 and ease of getting on or off. For example, preventing damage to the ladder 10 contributes to reducing the effort and cost of replacing parts. Furthermore, the good ease of getting on and off the ladder 10 improves convenience for operators who drive the dump truck 1 and workers who perform maintenance, ultimately enabling the dump truck 1 to operate efficiently.

[0035] Next, the main ladder device 11 of this embodiment will be compared with the technology described in Patent Document 1. The ladder of Patent Document 1 has left and right side beams formed by connecting a large number of complexly shaped blocks, resulting in a complex structure and high manufacturing costs. In contrast, the main ladder device 11 of this embodiment is configured by adding a support member 18 and a locking device 22 to a conventional existing ladder 10. The ladder 10 itself has a simple structure consisting of a pair of left and right side beams 10a and three steps 10b, the support member 18 has a simple structure made of welded steel pipes, and the locking device 22 has a simple structure consisting of a lock bracket 23 and a lock bar 24. Therefore, it can be manufactured more cheaply than the ladder of Patent Document 1, thereby reducing its manufacturing costs.

[0036] Furthermore, the ladder of Patent Document 1 has a complex block shape, which means that the claws do not mesh reliably, which can prevent the stringers from bending and resulting in damage in a collision with an obstacle. In contrast, the main ladder device 11 of this embodiment can reliably prevent damage to the ladder 10 by switching the support member 18 from the lower position to the upper position, and because the support member 18 is lightweight, this switching operation can be easily performed by the operator. As a result, the ladder can more reliably prevent damage in a collision with an obstacle than the ladder of Patent Document 1.

[0037] 9 and 11(b), the upper support member 18 protrudes upward from above the platform 9, and its horizontal connector 18b extends left and right in front of the operator and functions as part of a handrail. Although the platform 9 is quite high above the ground, the horizontal connector 18b located at the front gives the operator a sense of security when standing on the platform 9, and the operator can also hold on to the horizontal connector 18b to maintain stability. Furthermore, the horizontal connector 18b can prevent the operator from falling in the unlikely event that it happens.

[0038] The above has been explained about the main ladder device 11, but the maintenance ladder device 12 and the escape ladder device 13 have the same configuration. Therefore, although a duplicated explanation will not be given, the same operational effects as those described above can be achieved.

[0039] Also, unlike the dump truck 1 of this embodiment, there are cases where the main ladder device 11 is provided on either the left or right side of the vehicle body 2. Fig. 12 is a side view corresponding to Fig. 1, showing another example in which the main ladder device 11 is provided on the left side of the vehicle body 2. In this case, the main ladder device 11 is arranged in a position that differs by 90° in plan view, and the ladder 10 is arranged with a pair of side girders 10a arranged in front and behind, and a support member 18 is arranged on the right side of the ladder 10 (towards the vehicle body 2), but even with this arrangement, the same effects as those described above can be achieved.

[0040] That is, if the truck collides with an obstacle while traveling, the impact is input to the front stringer 10a, but the ladder 10 bends backward, preventing damage. Also, when the operator gets on or off the ladder 10, the support member prevents the ladder 10 from bending to the right, allowing the operator to get on or off easily. The same applies when the main ladder device 11 is provided at the rear of the vehicle body 2. As a result, the main ladder device 11 of this embodiment can achieve the desired effects without any problems regardless of its placement relative to the vehicle body 2, and can therefore be applied to various types of dump trucks 1.

[0041] Although the description of the embodiment has been completed above, the aspects of the present invention are not limited to this embodiment, and may be configured as follows, for example. (a) In the above embodiment, the ladder devices 11 to 13 are embodied in an extra-large dump truck 1 that operates in mines, etc. However, the type of work vehicle is not limited to this, and the device may also be applied to, for example, a wheel loader, as long as it is a work vehicle that is equipped with a ladder 10 for getting on and off the vehicle body.

[0042] (b) In the above embodiment, the lateral displacement prevention brackets 21l, 21r are welded to all steps 10b of the ladder 10 to prevent bending and twisting of the ladder 10 in the left-right direction, but this is not limited to this. For example, the lateral displacement prevention brackets 21l, 21r may be provided only on the lowest step 10b, or the lateral displacement prevention brackets 21l, 21r may be eliminated from all steps 10b. Furthermore, the shape of the steps 10b may be changed in place of the lateral displacement prevention brackets 21l, 21r. For example, as shown in FIG. 13, a pair of left and right notched surfaces 31l, 31r (corresponding to the "lateral displacement prevention portion" of the present invention) may be formed on the rear end of each step 10b, and these notched surfaces 31l, 31r may be abutted against the sliding contact portion 18d of the support member 18. 14, two pairs of left and right notched surfaces 31l, 31r (corresponding to the "lateral displacement prevention portion" of the present invention) may be formed at the rear end of each step 10b, and these notched surfaces 31l, 31r may be brought into contact with the sliding contact portion 18d of the support member 18. In either case, the same effects as those of the above embodiment can be achieved.

[0043] (c) In the above embodiment, the left and right side girders 10a of the ladder 10 are entirely made of rubber, but this is not limited to this. For example, the parts of the side girders 10a where the steps 10b are connected may be made of steel plate, or only the lower part of the side girders 10a, which are more likely to collide with obstacles, may be made of rubber, and the upper part of the side girders 10a may be made of steel plate.

[0044] (d) In the above embodiment, the left and right side girders 10a are made of rubber to give the ladder 10 flexibility, but wires or chains may be used instead. For example, as shown in FIG. 15, the left and right side girders may each be configured with a pair of wires 41 at the front and rear. Also, although not shown, the left and right side girders may each be configured with a pair of chains at the front and rear. Note that, since wires 41 and chains are more likely to bend and become unstable than rubber side girders 10a, it is desirable to provide anti-lateral slippage brackets 21l, 21r and notched surfaces 31l, 31r on the steps 10b.

[0045] (e) In the above embodiment, the ladder 10 is suspended from the vehicle body 2, but it is not limited to a completely vertical posture. For example, the ladder 10 may be maintained in a slightly oblique posture rather than vertical by providing a certain degree of rigidity to the left and right side beams 10a while maintaining flexibility to the extent that they can bend when colliding with an obstacle.

[0046] (f) In the above embodiment, the locking device 22 is configured to engage and release the locked portion 18c of the support member 18 in response to the rotation of the lock bar 24 pivotally supported by the lock bracket 23, but this is not limited to this. For example, the lock bar 24 may be slidably attached to the lock bracket 23, and the locked portion 18c of the support member 18 may be engaged and released in response to the slide.

[0047] (g) In the above embodiment, the locking device 22 was provided above the handrail 15 on the platform 9, so when the support member 18 was in the upper position, the operation to release the locking bar 24 was limited to being performed from above the platform 9 and could not be performed from the ground. Therefore, by providing the locking device 22 in a lower position and changing the position of the locked portion 18c of the support member 18 accordingly, it may be possible to make it possible to operate it from the ground.

[0048] For example, if the platform 9 is provided at a height within reach of an operator on the ground, the locking device 22 may be provided at a height near the platform 9, and the locked portion 18c may be provided on the lower part of the support member 18. When the operator on the ground pushes up the support member 18, the locked portion 18c is engaged with the lock bar 24 of the locking device 22, keeping the support member 18 in the upper position, and when the operator releases the engagement of the lock bar 24, the support member 18 can be switched to the lower position by its own weight. Of course, these operations can also be performed as desired on the platform 9.

[0049] In the above embodiment, the case where the vertical movement of the support member 18 is guided by the guide pipe 19 is described. However, it is sufficient that the support member 18 is provided on the ladder 10 so as to be vertically movable, and the guide pipe 19 does not have to be provided.

[0050] In the above embodiment, the support member 18 has the horizontal connecting portion 18b and the locked portion 18c. However, the support member 18 does not have to have the above configuration as long as it is configured to be fixed at a predetermined position, for example, at an upper position and a lower position.

[0051] For example, the support member 18 may be configured to penetrate the platform 9 at the rear of the ladder 10 and move in the vertical direction, and in the lower position, to abut against a plurality of steps 10b from the rear side to restrict bending of the ladder 10 toward the rear, and in the upper position, to allow bending of the ladder 10 toward the rear. [Explanation of symbols]

[0052] 1 Dump truck (work vehicle) 2. Body 9 Platform 10 ladder 10a stringer Step 10b 18 Support material 18d Sliding contact part 19 Guide pipe 21l, 21r Sideways movement prevention bracket (sideways movement prevention part) 31l, 31r Notched surface (sideways slip prevention part) 41 Wire

Claims

1. A ladder device for a work vehicle in which a ladder having a plurality of steps arranged vertically between a pair of flexible left and right side beams is suspended from a platform provided on a vehicle body, and in which people can get on and off between the platform and the ground via the plurality of steps from the front side of the ladder, A ladder device for a work vehicle, characterized in that the ladder is moved vertically through the platform at the rear side, and at a lower position, it abuts against the multiple steps from the rear side to restrict bending of the ladder toward the rear side, and at an upper position, it is provided with a support member that allows bending of the ladder toward the rear side.

2. At least one of the plurality of steps is provided with a lateral displacement prevention portion that abuts against the support member at the lower position and restricts bending of the ladder in the left-right direction.

2. The ladder device for a work vehicle according to claim 1.

3. The pair of stringers are each made of wire or chain.

2. The ladder device for a work vehicle according to claim 1.

4. The support member is formed in a frame shape by welding pipe materials and has a pair of left and right sliding contact portions, The ladder is provided with guide pipes that are provided on the vehicle body and through which the pair of left and right sliding contact portions of the support member are slidably inserted.

2. The ladder device for a work vehicle according to claim 1.

5. The support member has a horizontal connecting portion extending horizontally at its upper portion, and when in the upper position, the horizontal connecting portion protrudes upward from above the platform, allowing the horizontal connecting portion to function as a handrail.

2. The ladder device for a work vehicle according to claim 1.

6. The ladder device is provided at the front, rear, left or right side of the vehicle body.

2. The ladder device for a work vehicle according to claim 1.

Images