JP6411575B1 - lift device - Google Patents

Abstract

A lifting device that can be easily handled is provided.
A lifting device includes a frame, a crawler, a turning unit, and a hydraulic damper. A drive unit 11 that drives the crawler 20 is incorporated in the frame 10. The turning unit 30 has wheels 31 that are movable between a protruding position and a storage position. The damper 60 is provided between the frame 10 and the turning unit 30 so as to be extendable and contractible. When moving the wheel 31 from the protruding position to the storage position and storing the wheel in order to travel by the crawler 20, the lifting device 1 moves the piston 62 of the damper 60 to the working liquid when moving from the protruding position to the intermediate position. Move through to generate damping force. When moving the wheel 31 from the intermediate position to the storage position, the piston 62 moves above the oil level FS of the hydraulic oil F and moves without applying a damping force due to the fluid resistance of the hydraulic fluid.
[Selection] Figure 5

Description

  The present invention relates to a lifting device.

  Patent document 1 is disclosing the conventional raising / lowering apparatus. This lifting device includes a pair of left and right crawler type endless tracks (hereinafter simply referred to as crawlers) and a vehicle body having a drive source for driving the crawlers. In addition, a pair of left and right casters protruding downward from the crawler are provided at the front and rear of the lifting device. The elevating device travels by a crawler when traveling on stairs, and travels by front and rear casters when traveling on flat ground. Further, switching between caster traveling and crawler traveling is performed by driving an electric cylinder.

Japanese Patent Laid-Open No. 10-129541

  By the way, in the raising / lowering apparatus like patent document 1, switching with caster driving | running | working and crawler driving | running | working manually is also considered. In this case, depending on the size and weight of the device body and the load, excessive force is required for switching, or a large impact is generated due to the action of gravity or the like, which is expected to be difficult to handle. .

  This invention is made | formed in view of the said conventional situation, Comprising: It aims at providing the raising / lowering apparatus which can be handled easily.

  The lifting device of the present invention includes a frame, a crawler, a turning unit, and a damper. A drive unit is incorporated in the frame. A pair of crawlers is provided on the left and right sides of the frame and is driven by a drive unit. The swivel unit has wheels. The wheel is supported so as to be rotatable around a rotation axis orthogonal to the front-rear direction of the lifting device. In addition, the wheel has a protruding position in a state where the wheel protrudes below the lower surface of the crawler in a state of traveling on a flat ground, an intermediate position located on the inner peripheral surface of the crawler in a side view, and a protruding position from the intermediate position is opposite to the protruding position. It moves to the side and is provided so as to be freely movable between the storage positions stored in the inner peripheral surface of the crawler. The damper is telescopically disposed between the frame and the swivel unit. The damper has a cylinder, a piston, and a rod. The cylinder is filled with working liquid. The piston is housed in the cylinder so as to be movable in the axial direction. The rod has a distal end protruding outside the cylinder and a proximal end connected to the piston. The damper moves the piston in the working liquid when the wheel moves between the protruding position and the intermediate position, and the piston moves above the liquid level of the working liquid when the wheel moves between the intermediate position and the storage position. To move.

  With such a configuration, when the wheel is moved from the protruding position to the stowed position in order to perform crawler travel, the lifting device of the present invention moves the piston in the working liquid when moving from the protruding position to the intermediate position. The damping force due to the fluid resistance of the working liquid can be applied. For this reason, the impact which generate | occur | produces by effects, such as gravity, with the movement of a wheel can be relieved. In addition, when moving the wheel from the intermediate position to the storage position, the piston moves above the liquid level of the working liquid, so that the wheel can be easily moved without applying a damping force due to the fluid resistance of the working liquid. Can be made.

  Therefore, the lifting device of the present invention can be easily handled.

  In the lifting device of the present invention, the damper can apply an elastic force when the wheel moves from the intermediate position toward the protruding position. In this case, since an elastic force is applied in the moving direction of the wheel, the wheel can be easily moved.

It is a side view which shows the raising / lowering apparatus of Embodiment 1. It is a top view which shows the raising / lowering apparatus of Embodiment 1. It is a rear view which shows the raising / lowering apparatus of Embodiment 1. It is a figure for demonstrating the state at the time of the stairs raising / lowering of the raising / lowering apparatus of Embodiment 1. FIG. It is a side view which shows the raising / lowering apparatus of Embodiment 1, and is a figure for demonstrating the effect | action of a turning unit. It is a side view which shows the raising / lowering apparatus of Embodiment 1, and shows the state which has a wheel in a protrusion position. It is a principal part enlarged view of FIG. It is a side view which shows the raising / lowering apparatus of Embodiment 1, and shows the state which has a wheel in an intermediate position. It is a principal part enlarged view of FIG. It is a side view which shows the raising / lowering apparatus of Embodiment 1, and shows the state which has a wheel in a storage position. It is a principal part enlarged view of FIG.

  A first embodiment of the lifting device of the present invention will be described with reference to the drawings. In the following description, for the front and rear directions, the traveling direction when moving down the stairs (left side in FIG. 1) is the forward direction when moving up and down (rightward in FIG. 1). ) Is defined as the rear of the lifting device. As for the vertical direction, the vertical direction shown in FIGS. 1 and 3 is defined as the vertical direction of the lifting device as it is.

<Embodiment 1>
The lifting device 1 according to the first embodiment is a device that lifts and lowers stairs. As shown in FIGS. 1 to 3, the lifting device 1 includes a frame 10, a crawler 20, a turning unit 30, and a damper 60. Further, the lifting device 1 includes a loading platform 40 and a handle 50.
As illustrated in FIGS. 1 to 3, the frame 10 includes a horizontal portion 10 </ b> A, an inclined portion 10 </ b> B, and a crawler guide portion 10 </ b> C. A drive unit 11 is incorporated in the frame 10.

  The horizontal portion 10A is provided with members extending in the front-rear direction arranged in parallel to the left and right. The inclined portion 10B is formed to extend rearward and obliquely upward from the rear end of the horizontal portion 10A. A pair of crawler guide portions 10C is provided on the left and right sides of the horizontal portion 10A and the inclined portion 10B. The crawler guide portion 10C has a groove that opens downward and extends in the front-rear direction. As shown in FIG. 1, the crawler guide portion 10 </ b> C is formed to extend along the direction in which the horizontal portion 10 </ b> A and the inclined portion 10 </ b> B extend in a side view. The frame 10 has a handle support portion 10D. The handle support portion 10D supports a handle 50 described later.

  As shown in FIG. 1, the drive unit 11 has a motor 11A, a drive shaft 11B, and a drive pulley 11C. The motor 11A is a drive source for the crawler 20 and is driven by a battery (not shown). The drive shaft 11B is rotatably supported on the frame 10. The drive shaft 11B rotates when the power of the motor 11A is transmitted by the sprocket and the chain. The drive pulley 11C is a toothed pulley around which the crawler 20 is wound. As shown in FIG. 1, a follower unit 12 is incorporated in the frame 10. The driven unit 12 has a driven shaft 12A and a driven pulley 12B. The driven shaft 12A is rotatably supported by the frame 10. The crawler 20 is wound around the driven pulley 12B.

  A pair of crawlers 20 is provided on the left and right sides of the frame 10. As shown in FIG. 1, the crawler 20 has a substantially triangular ring shape when viewed from the side, and is wound around the drive pulley 11C, the driven pulley 12B, and the crawler guide portion 10C. The crawler 20 is a rubber crawler. The crawler 20 is provided with a plurality of teeth at predetermined intervals on the back surface thereof, and these teeth mesh with the teeth of the drive pulley 11C to transmit the power of the drive unit. In addition, waved undulations are formed on the surface of the crawler 20 (the surface that contacts the stairs when the stairs are raised and lowered). As shown in FIG. 4, the crawler 20 abuts on the corner of the staircase S at the site (the lower side shown in FIG. 1) guided by the crawler guide portion 10 </ b> C when the staircase S is raised and lowered. By driving the crawler 20 in this state, the lifting device 1 moves up and down the stairs S by the crawler guide portion 10 </ b> C sliding on the back surface of the crawler 20. Each crawler 20 is wound around with a length that spans at least two or more corners of the staircase S so as to contact the ground when the stairs S are moved up and down.

  The turning unit 30 has wheels 31. The wheel 31 is supported rotatably around a rotation axis A1 extending in a direction perpendicular to the front-rear direction (the left-right direction in FIGS. 2 and 3). In the present embodiment, the turning unit 30 has two wheels 31. The wheels 31 are arranged side by side along the direction in which the rotation axis A1 extends. As shown in FIGS. 2 and 3, the distance between these two wheels 31 is about ３ of the device width. As shown in FIG. 5, the wheel 31 has a protruding position (a position indicated by a two-dot chain line in FIG. 5) in a state of protruding below the lower end of the crawler 20 in a state of traveling on a flat ground, and a side view of the crawler 20. An intermediate position (a position indicated by a one-dot chain line in FIG. 5) located inside the outer peripheral surface, and a storage position (FIG. 5) in a state of moving from the intermediate position to the opposite side to the protruding position and being stored inside the outer peripheral surface of the crawler 20 Between the positions indicated by the solid lines). In the present embodiment, this storage position is a position further inside than the intermediate position.

  In the present embodiment, the turning unit 30 is supported by the frame 10 so as to be rotatable around a rotation axis A2 shown in FIG. The rotation axis A2 is an axis extending in a direction orthogonal to the front-rear direction, and is an axis parallel to the rotation axis A1 of the wheel 31. The turning unit 30 is provided with a wheel 31 at the lower end and an operation lever 32 at the upper end with the rotation axis A2 in between.

  The operation lever 32 is a lever operated when changing the position of the wheel 31. The operation lever 32 is provided in front of the handle 50 so as to be movable in the front-rear direction. The operation lever 32 moves the wheel 31 in the direction from the protruding position to the storage position when moved forward, and moves the wheel 31 in the direction from the storage position toward the protruding position when moved backward. The swivel unit 30 is rotated about the rotation axis A2 by moving the operation lever 32 in the front-rear direction, so that the entire wheel unit 31 is rotated. The turning unit 30 moves the wheel 31 between the protruding position and the storage position by this rotation.

  As shown in FIG. 1, the turning unit 30 has a first lock mechanism 33 and a second lock mechanism 34. The first lock mechanism 33 locks the wheel 31 in a state where it is in the storage position. The second lock mechanism 34 locks the wheel 31 in the protruding position. Specifically, the first lock mechanism 33 locks the first locking portion 33A on the frame 10 side and the first locked portion 33B on the operation lever 32 side by operating the operation lever 32 forward. By doing so, it is locked. As a result, the operation lever 32 is held in a state where it is moved forward, and is locked while the wheel 31 is in the storage position.

  The second lock mechanism 34 locks the wheel 31 in the protruding position. Specifically, the second lock mechanism 34 operates the operation lever 32 backward to lock the second locking portion 34A on the frame 10 side and the second locked portion 34B on the operation lever 32 side. By doing so, it is locked. As a result, the operation lever 32 is held in a state where it is moved backward, and is locked while the wheel 31 is in the protruding position.

  The loading platform 40 is arranged on the upper part of the frame 10 and places the load B thereon. As shown in FIG. 1, the loading platform 40 is formed in a form in which two substantially L-shaped shelves in a side view are vertically stacked. The loading platform 40 is disposed such that a portion corresponding to the back plate of the L-shaped shelf is inclined rearward at an angle substantially parallel to the inclined portion 10 </ b> B of the frame 10. A poly tank is mounted as a load B on the loading platform of the lifting device 1 according to the present embodiment. A total of four 20-liter polytanks can be placed on the loading platform 40, two per shelf.

  The handle 50 is disposed at the rear part of the lifting device 1. In the present embodiment, the handle 50 is formed to extend rearward from the loading platform. Specifically, as shown in FIG. 1, the handle 50 is formed such that the lower end portion is supported by the handle support portion 10 </ b> D and extends rearward and obliquely upward. The handle 50 is supported by the handle support portion 10D so as to be rotatable about the extending direction as a central axis and movable in the extending direction. A pair of handles 50 are arranged side by side in the left-right direction at a predetermined interval. Each handle 50 includes a linear portion 50A that linearly extends rearward and obliquely upward along the extending direction of each handle support portion 10D, and a curved portion 50B that is curved outward from the upper end of the linear portion 50A in the left-right direction. And have. As shown in FIG. 2, the handle 50 is provided such that the width W1 of the left and right linear portions 50A is narrower than the width Wc of the pair of crawlers 20. On the other hand, the width W2 of the left and right curved portions 50B is wider than the width Wc of the crawler 20, but can be accommodated within the width W1 of the linear portion 50A by rotating.

  Each handle 50 has a grip 51 and a positioning part 52. The grip 51 is gripped by the operator of the lifting device 1 and is operated to change the direction of travel or to turn. The left and right grips 51 are provided with an interval (for example, 450 mm or more) that allows a person to enter. In addition, an operation switch 51 </ b> A for performing a driving operation of the crawler 20 is provided at the inner end of the grip 51. The operation switch 51A is provided on each of the two grip portions 51. The positioning portion 52 is provided at the lower end portion of the handle 50 with the handle support portion 10D interposed therebetween. The positioning unit 52 performs positioning when the handle 50 is rotated and moved in the extending direction.

  The damper 60 is disposed between the frame 10 and the turning unit 30 so as to be extendable and contractible. The damper 60 has a cylinder 61, a piston 62, and a rod 63. In the present embodiment, the damper 60 is a hydraulic damper. The cylinder 61 is filled with hydraulic oil F as a hydraulic fluid. The cylinder 61 is filled with a compressed gas G. The piston 62 is accommodated in the cylinder 61 so as to be movable in the axial direction. The rod 63 protrudes outside the cylinder 61 at the tip end side. The rod 63 is connected to the piston 62 at the base end. As shown in FIGS. 5 to 11, the damper 60 has an end portion on the cylinder 61 side connected to the operation lever 32 of the turning unit 30 and an end portion on the rod 63 side connected to the frame 10. The damper 60 expands while applying an urging force due to the gas pressure of the compressed gas G at the time of expansion, and a pressure that contracts against the urging force due to the gas pressure while applying a damping force due to the fluid resistance of the hydraulic oil F when contracting. It is an effective damper.

  In the damper 60, when the wheel 31 moves between the protruding position (position shown in FIG. 6) and the intermediate position (position shown in FIG. 8), the piston 62 moves in the hydraulic oil F that is the working liquid. In the damper 60, when the wheel 31 moves between the intermediate position and the storage position (position shown in FIG. 10), the piston 62 moves above the oil level FS of the hydraulic oil F. In the case of the present embodiment, the damper 60 moves in the hydraulic oil F until the damper 60 is contracted from the most extended state to a predetermined length in the lifting device 1 in a state where the damper 60 travels on a flat ground. In a state of contracting more than the length, the piston 62 moves above the oil level FS of the hydraulic oil F, that is, in the compressed gas G. Therefore, in a state where the wheel 31 is in the intermediate position, the piston 62 is located above the oil level FS of the hydraulic oil F. As described above, in the damper 60 of the first embodiment, the hydraulic oil F is sealed in the cylinder 61 with the amount of oil that moves the piston 62 in the cylinder 61 in such a form.

  Further, the damper 60 applies an elastic force when the wheel 31 moves from the storage position toward the protruding position. In the case of the present embodiment, an elastic force acts on the damper 60 in the extending direction by the action of the compressed gas G sealed in the cylinder 61. The damper 60 imparts such elastic force to the turning unit 30. And by this elastic force, the turning unit 30 is urged to turn around the turning axis A2. The elastic force of the damper 60 acts in the direction in which the wheel 31 moves from the storage position to the protruding position in the turning unit 30.

  Further, the damper 60 applies a damping force when the wheel 31 moves from the protruding position to the storage position. Specifically, the damper 60 contracts while moving the piston 62 in the hydraulic oil F when the operation lever 32 moves forward, thereby applying a damping force. Further, as shown in FIG. 5, the damper 60 tilts as the turning unit 30 rotates. The damper 60 tilts within an angle θ of 20 ° to 60 ° formed by an imaginary line connecting a connecting portion with the turning unit 30 and the rotation axis A2 of the turning unit 30 and the central axis of the damper 60. .

Next, the operation of the lifting device 1 having the above configuration will be described.
The lifting device 1 travels with a pair of crawlers 20 when moving up and down the stairs. In raising and lowering the stairs, first, the position of the wheel 31 of the turning unit 30 is switched from the protruding position to the storage position. Specifically, first, the lock of the second lock mechanism 34 is released in order to unlock the wheel 31 in the protruding position. Then, the operation lever 32 is moved forward, and the turning unit 30 in a state where the wheel 31 shown in FIG. 6 is in the protruding position is turned around the turning axis A2. At this time, gravity acting on the lifting device 1 acts as a force for urging the wheel 31 from the protruding position toward the storage position. However, in the damper 60, the piston 62 moves in the hydraulic oil F when the wheel 31 moves between the protruding position and the intermediate position.

  That is, as shown in FIGS. 6 and 7, when the wheel 31 is in the protruding position, the piston 62 is immersed in the hydraulic oil F, and the piston 60 is contracted in a direction in which the damper 60 contracts from this state. 62 moves in the hydraulic oil F. Accordingly, the damper 60 generates a damping force due to the fluid resistance of the hydraulic oil F. Further, the damper 60 applies an elastic force in the extending direction due to the gas pressure to the turning unit 30. On the other hand, the gravity of the entire lifting device 1 acts on the wheel 31. The damping force and elastic force of the damper 60 act against the gravity applied to the lifting device 1. Thereby, the rapid movement of the wheel 31 in the direction of the storage position, in other words, the sudden drop of the lifting device 1 is alleviated.

  If the wheel 31 is moved to the intermediate position which is a position inside the outer peripheral surface of the crawler 20 in a side view, the wheel 31 is moved to the storage position next. In the damper 60, when the wheel 31 moves between the intermediate position and the storage position, the piston 62 moves above the oil level FS of the hydraulic oil F. Specifically, as shown in FIGS. 8 and 9, in the state where the wheel 31 is in the intermediate position, the damper 60 is positioned in the compressed gas G with the piston 62 protruding upward from the oil level FS of the hydraulic oil F. doing. From this state, the operation lever 32 is moved further forward to rotate the turning unit 30, and the wheel 31 is further moved in the direction of the storage position shown in FIGS. In this case, the damper 60 contracts as the piston 62 moves in the compressed gas G above the oil level FS. Thus, since the piston 62 moves in the compressed gas G above the oil level FS, the damper 60 contracts without generating a damping force by the hydraulic oil F. For this reason, the operation lever 32 can be easily moved forward, and the turning unit 30 can be easily rotated to easily move the wheel 31 to the storage position. Finally, the first lock mechanism 33 is locked and the wheel 31 is fixed at the storage position.

  In this way, when the wheel 31 is stored in the storage position and the elevating device 1 is driven by the crawler 20, the wheel 31 is again moved to the projecting position when traveling on the flat ground or turning on the landing of the stairs S. Move to. Specifically, the lock of the first lock mechanism 33 is released. Then, the operation lever 32 is moved backward, the turning unit 30 is rotated, and the wheel 31 is moved. At this time, since the damper 60 applies an elastic force in the extending direction, the operation lever 32 can be easily moved. Finally, the second lock mechanism 34 is locked to fix the wheel 31 at the protruding position.

  In addition, when turning or running on a flat ground using the wheels 31, the grip portion 51 of the handle 50 is gripped and pushed downward, and the front portion of the lifting device 1 is lifted around the wheel 31 as an axis. As a result, only the projecting wheels 31 are grounded, and the wheels 31 can turn or run on a flat ground.

  As described above, the lifting device 1 includes the frame 10, the crawler 20, the turning unit 30, and the damper 60. A drive unit 11 is incorporated in the frame 10. A pair of crawlers 20 is provided on the left and right sides of the frame 10 and is driven by the drive unit 11. The turning unit 30 has wheels 31. The wheel 31 is supported so as to be rotatable around a rotation axis A1 orthogonal to the front-rear direction of the lifting device 1. Further, the wheel 31 has a projecting position in a state of projecting downward from the lower surface of the crawler 20 in a state of traveling on a flat ground, an intermediate position positioned inside the outer peripheral surface of the crawler 20 in a side view, and a projecting position from the intermediate position. It is provided so as to be movable between the storage position in a state of moving to the opposite side and stored inside the outer peripheral surface of the crawler 20. The damper 60 is disposed between the frame 10 and the turning unit 30 so as to be extendable and contractible. The damper 60 has a cylinder 61, a piston 62 and a rod 63. The cylinder 61 is filled with hydraulic oil F which is a working liquid. The piston 62 is accommodated in the cylinder 61 so as to be movable in the axial direction. The rod 63 has a distal end protruding outside the cylinder 61 and a proximal end connected to the piston 62. In the damper 60, when the wheel 31 moves between the protruding position and the intermediate position, the piston 62 moves in the hydraulic oil F, and when the wheel 31 moves between the intermediate position and the storage position, the piston 62 moves to the hydraulic oil. It moves above the oil level FS of F.

  With such a configuration, when the elevating device 1 moves the wheel 31 from the protruding position to the storage position in order to travel by the crawler 20, the piston 62 moves through the hydraulic oil F in the movement from the protruding position to the intermediate position. Since it moves, the damping force by the fluid resistance of the hydraulic oil F can be made to act. For this reason, the impact which generate | occur | produces by effects, such as gravity, with the movement of the wheel 31, can be relieved. Further, when moving the wheel 31 from the intermediate position to the storage position, the piston 62 moves above the oil level FS of the hydraulic oil F. Thereby, the wheel 31 can be easily moved without applying the damping force due to the fluid resistance of the hydraulic oil F.

  Therefore, the lifting device 1 can be easily handled.

  The damper 60 gives an elastic force when the wheel 31 moves from the intermediate position toward the protruding position. Thereby, since an elastic force is provided in the moving direction of the wheel 31, the wheel 31 can be easily moved.

The present invention is not limited to the first embodiment described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the first embodiment, the wheel is moved between the protruding position and the storage position by rotating around the predetermined rotation axis, but this is not essential. The form in which the wheel moves between the protruding position and the storage position is not particularly limited, and for example, a form in which the wheel linearly moves in the vertical direction may be used.
(2) In the first embodiment, the turning unit has an operation lever that switches the position of the wheel. However, this is not essential. The configuration for the turning unit to switch the position of the wheel is not particularly limited.
(3) In the first embodiment, the damper gives an elastic force when the wheel moves from the intermediate position toward the protruding position, but this is not essential. Further, when the damper imparts an elastic force, the elastic force is not limited to the elastic force due to the gas pressure of the compressed gas, and may be an elastic force by other means such as a compression coil spring or a combination thereof.
(4) In the first embodiment, the hydraulic oil is employed as the working liquid sealed in the cylinder. However, the present invention is not limited to this, and any other liquid (for example, water) may be used as long as it generates a predetermined damping force. May be adopted.
(5) In the first embodiment, the poly tank is exemplified as the load, but the load conveyed by the lifting device is not particularly limited.
(6) Although the number of wheels is two in the first embodiment, it may be one or three or more.
(7) Although the rubber crawler is exemplified as the crawler in the first embodiment, a crawler using another material such as a metal crawler or a combination of these materials may be used.
(8) In the first embodiment, the crawler is hung around the crawler guide portion in such a length that the portion serving as the ground contact surface straddles at least two corners of the staircase when the stairs are raised and lowered. From the viewpoint of stability during ascent and descent, it is preferable that the length spans three or more corners of the staircase.

  DESCRIPTION OF SYMBOLS 1 ... Lifting device, 10 ... Frame, 10A ... Horizontal part, 10B ... Inclination part, 10C ... Crawler guide part, 10D ... Handle support part, 11 ... Drive unit, 11A ... Motor, 11B ... Drive shaft, 11C ... Drive pulley, DESCRIPTION OF SYMBOLS 12 ... Drive unit, 12A ... Drive shaft, 12B ... Drive pulley, 20 ... Crawler, 30 ... Turning unit, 31 ... Wheel, 32 ... Operation lever, 33 ... 1st lock mechanism, 33A ... 1st latching | locking part, 33B ... 1st locked part, 34 ... 2nd locking mechanism, 34A ... 2nd locking part, 34B ... 2nd locked part, 40 ... loading platform, 50 ... handle, 50A ... linear part, 50B ... curved part, DESCRIPTION OF SYMBOLS 51 ... Holding part, 51A ... Operation switch, 52 ... Positioning part, 60 ... Damper, 61 ... Cylinder, 62 ... Piston, 63 ... Rod, A1 ... Wheel rotation axis, A2 ... Swing unit rotation axis, B ... Loading , S ... stairs, W1 ... width of the straight portion of the handle, W2 ... width of the curved portion of the handle, Wc ... width of the crawler, .theta .... the connecting portion of the damper with the turning unit and the turning shaft of the turning unit 30. The angle between the connected virtual line and the central axis of the damper

Claims (2)

A frame incorporating a drive unit;
A pair of crawlers provided on the left and right sides of the frame and driven by the drive unit;
A projecting position that is supported rotatably around a rotation axis that is orthogonal to the front-rear direction and projects below the lower surface of the crawler when traveling on flat ground, and an intermediate position that is located inside the outer peripheral surface of the crawler in a side view A swivel unit having a wheel provided so as to be movable between a position and a storage position in a state of being stored inside the outer peripheral surface of the crawler from the intermediate position to the opposite side of the protruding position;
A cylinder filled with a working liquid, a piston accommodated in the cylinder so as to be movable in the axial direction, and a rod having a distal end protruding outside the cylinder and a base end connected to the piston. The piston is moved in the working liquid when the wheel moves between the projecting position and the intermediate position, and the wheel is moved to the intermediate position. And a damper for moving the piston above the liquid level of the working liquid when moving between the storage position and the storage position;
A lifting device characterized by comprising:   The lifting device according to claim 1, wherein the damper applies an elastic force when the wheel moves from the intermediate position toward the protruding position.

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