Movable gyration caster and cart having the same

Abstract

To provide a movable gyration caster capable of selectively exerting a rectilinear travel capability, and a cart having the same.SOLUTION: Between a first position where a cargo loading base 1 is supported with a gyration axis X2 extending in a vertical direction and a second position where the cargo loading base 1 is supported with the gyration axis X2 inclined, a movable gyration caster MC is turnable about a turning shaft X3. The gyration axis X2 at the second position is inclined at an angle of inclination α so that the lower part of the gyration axis X2 is located by the side of the turning shaft X3 beyond the gyration axis X2 at the first position. A distance D1 between a rotation shaft X1 of a wheel 11 and the gyration axis X2, a distance D2 between the turning shaft X3 and the gyration axis X2, and a distance 3 between the rotation shaft X1 in an axial direction of the gyration axis X2 and the turning shaft X3 satisfy D1≥D2>0 and D1+D2≥D3×tanα.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a movable swivel caster and a cart equipped with the same. [Background technology]

[0002] There is a cart that is provided with a pair of casters on the front and rear sides. Typically, the casters on either the front or rear side are swivel casters that allow the wheels to change direction, and the casters on the other side are fixed casters that do not allow the wheels to change direction. Patent Document 1 discloses a related technique. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6279850 Summary of the Invention [Problem to be solved by the invention]

[0004] Fixed casters have excellent directional stability (also called straight-line running ability) when moving straight in the direction the wheels are facing, but they are difficult to move or adjust to the side, which is the direction that intersects the fixed direction. On the other hand, swivel casters are easy to move and adjust to the side, but are inferior in straight-line running ability.

[0005] An object of the present invention is to provide a movable swivel caster that can selectively exhibit straight-line running performance, and a cart equipped with the same. [Means for solving the problem]

[0006] A movable swivel caster according to one aspect of the present invention is rotatable around a rotation axis between a first position where the rotation axis supports the load platform with the load platform extended in the vertical direction, and a second position where the rotation axis supports the load platform with the load platform tilted. The rotation axis in the second position is tilted at an inclination angle α so that a lower portion of the rotation axis is located closer to the rotation axis than the rotation axis in the first position. The distance D1 between the rotation axis of the wheel and the rotation axis, the distance D2 between the rotation axis and the rotation axis, and the distance D3 between the rotation axis and the rotation axis in the axial direction of the rotation axis satisfy D1≧D2>0 and D1+D2≧D3×tanα. Effect of the Invention

[0007] According to the present invention, it is possible to provide a movable swivel caster that can selectively exhibit straight-line running performance, and a cart equipped with the same. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view of a carriage according to the first embodiment. [Diagram 2] FIG. 2 is a side view showing a state in which the movable swivel caster according to the first embodiment is in a first position. [Diagram 3] FIG. 4 is a side view showing a state in which the movable swivel caster according to the first embodiment is in a second position. [Figure 4] FIG. 2 is a side view of the fixed swivel caster according to the first embodiment. [Diagram 5] FIG. 2 is a plan view of the dolly with the top plate removed according to the first embodiment. [Figure 6] FIG. 2 is a bottom view of the carriage according to the first embodiment. [Figure 7] FIG. 11 is a side view of the carriage according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A movable swivel caster and a cart equipped with the same according to some embodiments will be described with reference to the drawings. In the following description, components having the same functions as those already described will be denoted by the same reference numerals and will not be described.

[0010] First Embodiment The dolly T1 is mainly used for transporting luggage by human power, and is also called a hand truck. As shown in Fig. 1, the dolly T1 is of a single-arm type and includes a loading platform 1 and a sleeve 2 provided at the rear of the loading platform 1. The upper surface of the loading platform 1 is flat, and forms a loading surface 1a on which luggage is placed.

[0011] As shown in FIG. 1, the loading platform 1 has a frame 3 and a top plate 4 fixed on the frame 3. The frame 3 has a rectangular shape in a plan view and is made of shaped steel such as angle steel. The frame 3 includes a left member 3L, a right member 3R, and a center member 3C extending in the front-rear direction of the trolley T1, and a front member 3F and a rear member 3B extending in the width direction of the trolley T1. The left member 3L extends along the left edge of the loading platform 1, the right member 3R extends along the right edge of the loading platform 1, and the center member 3C extends along the width center of the loading platform 1 between the left member 3L and the right member 3R. The front member 3F extends along the front edge of the loading platform 1, and the left end, right end, and center of the front member 3F are connected to the front ends of the left member 3L, the right member 3R, and the center member 3C, respectively. The rear material 3B extends along the rear edge of the bed 1, and the left end, right end, and center of the rear material 3B are connected to the rear ends of the left material 3L, right material 3R, and center material 3C, respectively. The top plate 4 is a plate material that is rectangular in plan view and is made of, for example, a resin plate or a steel plate. At the front of the bed 1, one front cross material 5 extending in the width direction of the trolley T1 is fixed to the underside of the frame 3. At the rear of the bed 1, two rear cross materials 6 extending in the width direction of the trolley T1 are fixed to the underside of the frame 3.

[0012] The sleeve 2 has a gate-like shape and includes left and right pillar members 7 whose lower ends are fixed to the rear end of the frame 3, and a cross member 8 that connects the upper ends of the pillar members 7. The cross member 8 includes a handle portion 9 that a user holds when operating the trolley T1.

[0013] The dolly T1 is provided with one swivel caster at each of the four corners of the bottom of the loading platform 1. Specifically, a front caster MC which is a movable swivel caster MC is attached to the front of the loading platform 1, and a rear caster C which is a fixed swivel caster C is attached to the rear of the loading platform 1.

[0014] As shown in Figs. 2 to 4, each swivel caster, i.e., the front caster MC and the rear caster C, includes a wheel 11, a swivel fitting 12, a swivel unit 13, and a top plate 14. The wheel 11 is supported by a wheel axle 11a. The wheel 11 is rotatable around a rotation axis X1, which is the central axis of the wheel axle 11a. The swivel fitting 12 rotatably supports the wheel 11 via the wheel axle 11a. The swivel fitting 12 is attached to the top plate 14 via the swivel unit 13 so as to be rotatable around a rotation axis X2. The rotation axis X2 is perpendicular to a straight line parallel to the rotation axis X1, but does not intersect with the rotation axis X1. A bearing (not shown) is built into the swivel unit 13.

[0015] As shown in Fig. 4, the top plate 14 of the rear caster C is fastened to a base plate 15 fixed to the lower surface of the rear cross material 6 by bolts or the like (not shown). That is, the rear caster C is fixed to the platform 1 with the swivel axis X2 extending in the vertical direction. The front caster MC is rotatably supported by a shaft 17 provided below the platform 1 as shown in Figs. 2 and 3. Specifically, in the front caster MC, the top plate 14 is fastened to the lower surface of a base plate 18 rotatably supported by the shaft 17 by bolts or the like (not shown). The shaft 17 is inserted into a pillow-type bearing unit 19 attached to the upper surface of the base plate 18 to support the front caster MC.

[0016] The front caster MC is rotatable around a rotation axis X3, which is the central axis of the shaft 17, between a first position shown in Fig. 2 and a second position shown in Fig. 3. In other words, the shaft 17 constitutes the rotation axis X3 of the front caster MC. The front caster MC is attached to the platform 1 such that the rotation axis X2 is located forward of the rotation axis X3 when the front caster MC is in the first position. The rotation axis X3 is parallel to a straight line that intersects with the rotation axes X2 of the left and right rear casters C and is parallel to the top surface of the platform 1.

[0017] In the first position, the front caster MC supports the platform 1 with the pivot axis X2 extending in the vertical direction, and in the second position, the front caster MC supports the platform 1 with the pivot axis X2 tilted. The pivot axis X2 in the second position is tilted at an inclination angle α so that the lower portion of the pivot axis X2 is located closer to the pivot axis X3 side (rearward in this embodiment) than the pivot axis X2 in the first position.

[0018] In this embodiment, the inclination angle α of the rotation axis X2, i.e., the angle between the rotation axis X2 and the up-down direction, is set to 20°. The inclination angle α is desirably set within a range of 10° to 45°. If the inclination angle α is less than 10°, it is difficult to obtain sufficient straight-line running performance, which will be described later. If the inclination angle α is greater than 45°, an excessive moment is likely to be applied to the rotating part 13. The inclination angle α can be determined within the above range, taking into consideration, for example, the unevenness and degree of inclination of the road surface in the usage environment of the bogie T1, the maximum allowable load of the casters to be used, and the like.

[0019] In the first position, the front caster MC is in an omnidirectional travel mode, and is in a freely swivelable state that allows easy travel in any horizontal direction. In this state, for example, when the bogie T1 is moving forward, if the orientation of the wheel 11 shifts in a direction intersecting the front-rear direction, a lateral load (side force) acts on the wheel 11 from the road surface, and a turning moment is generated that causes the wheel 11 to turn backward around the turning axis X2. This turning moment always acts in a direction that restores the orientation of the wheel 11 when the orientation of the wheel 11 deviates in a direction intersecting the front-rear direction. Hereinafter, the turning moment that acts in a direction that restores the orientation of the wheel 11 is also referred to as a restoring moment.

[0020] In the second position, the front caster MC is in a straight-line running mode and exhibits straight-line running performance. In the second position, the pivot axis X2 is inclined, so that the reaction force from the road surface resulting from the weight of the luggage and the dolly T1 acts on the wheel 11 with a component in a direction non-parallel to the pivot axis X2. This component always acts in a direction to restore the wheel 11 when the orientation of the wheel 11 deviates in a direction intersecting the moving direction of the dolly T1. That is, in the second position, the restoring moment is strengthened by the above-mentioned component of the road surface reaction force, making it more difficult for the front caster MC to turn than in the first position. That is, when the front caster MC is in the second position, it can exhibit high straight-line running performance.

[0021] In the front caster MC, the distance D1 between the rotation axis X1 and the swivel axis X2, the distance D2 between the rotation axis X3 and the swivel axis X2, and the distance D3 between the rotation axis X1 and the swivel axis X3 in the axial direction of the swivel axis X2 satisfy the formulas (1) and (2). In other words, the distance D3 is the distance between the rotation axis X3 and a plane perpendicular to the swivel axis X2 that includes the rotation axis X1. D1 ≧ D2 > 0 (1) D1 + D2 ≧ D3 × tan α (2)

[0022] Moreover, the distance D1 and the distance D2 satisfy the formula (3). D2 ≧ 0.75 × D1 (3)

[0023] Since formula (1) is satisfied, when the front caster MC is in the first position and the bogie T1 moves forward (travels in the direction from the rotation axis X3 to the swivel axis X2), the rotation axis X1 of the wheel 11 is located directly below the rotation axis X3 or behind the rotation axis X3. At this time, the resultant force of the road surface reaction force and the rolling resistance input to the wheel 11 forms a first moment (counterclockwise moment when viewed from the left side) that rotates the front caster MC from the first position to the second position around the rotation axis X3. Then, the front caster MC receives this first moment and rotates from the first position to the second position. That is, the front caster MC is switched to the straight running mode and can exhibit straight running performance simply by moving the front caster MC in the direction from the rotation axis X3 to the swivel axis X2 (in this embodiment, moving the bogie T1 forward).

[0024] Furthermore, when the front caster MC is in the second position and the bogie T1 moves backward (travels in the direction from the pivot axis X2 toward the pivot axis X3), when the orientation of the wheel 11 shifts in a direction intersecting the front-to-rear direction, a lateral load acts on the wheel 11 in the forward direction, which is the opposite direction to the movement direction of the bogie T1. If the bogie T1 is then moved backward in this state, the rotation moment formed around the pivot axis X2 by the lateral load becomes larger than the above-mentioned restoring moment, and the front caster MC rotates so that the rotation axis X1 of the wheel 11 moves forward of the pivot axis X2 (see the two-dot chain line in FIG. 3). At this time, since formula (2) is satisfied, the resultant force of the road reaction force and the rolling resistance input to the wheel 11 forms a second moment (clockwise moment when viewed from the left side) that rotates the front caster MC from the second position to the first position around the pivot axis X3. Then, the front caster MC receives this second moment and rotates from the second position to the first position. That is, by simply moving the front caster MC in the direction from the pivot axis X2 toward the pivot axis X3 (in this embodiment, moving the cart T1 backward), the mode is switched to the omnidirectional traveling mode, and the cart can easily travel in any direction in the horizontal direction.

[0025] As shown in Figs. 2, 3, 5 and 6, the rotation axes X3 of the left and right front casters MC are on the same straight line, and one shaft 17 extending in the width direction of the dolly T1 constitutes the rotation axis X3 of the left and right front casters MC. The left and right front casters MC are connected to each other by a connecting member 20. The connecting member 20 is fixed to a portion of each front caster MC that is located on the same side (rear side) of the rotation axis X3 and on the opposite side (rear side) of the swivel axis X2 across the rotation axis X3. In this embodiment, the connecting member 20 is a plate-shaped member extending in the width direction of the dolly T1, and the front edge portions of both ends in the width direction are fastened to the rear ends of the base plates 18 of the left and right front casters MC by bolts 21. The shaft 17 is supported by the platform 1 at both ends located outside the width direction of the dolly T1 from the left and right front casters MC and at a portion located between the left and right front casters MC. Specifically, the shaft 17 is supported on the platform 1 via pillow-type bearing units 22 attached to the undersides of the left member 3L, the right member 3R, and the central member 3C of the frame 3.

[0026] 2 and 3, in this embodiment, an adjustment bolt 23 for adjusting the attitude of the swivel axis X2 in the first position is provided at the front end of each base plate 18 of the left and right front casters MC. When the front caster MC is in the first position, the head of the adjustment bolt 23 abuts against the underside of the front cross material 5. By increasing or decreasing the length of the adjustment bolt 23, the base plate 18 can be tilted forward or backward, thereby adjusting the inclination angle of the swivel axis X2 in the first position.

[0027] 1 and 6, the trolley T1 may include a rotation lock mechanism 30. The rotation lock mechanism 30 locks the rotation of the front caster MC at each of the first position and the second position. The rotation lock mechanism 30 includes an operation unit 31 provided on the handle unit 9 to which a user's operating force is input, a lock unit 32 provided in the vicinity of the connecting member 20, and a transmission unit 33 that transmits the operating force input to the operation unit 31 to the lock unit 32.

[0028] The operating unit 31 includes a lever 34. The lever 34 is rotatably supported by a bracket 35 provided in the vicinity of the handle unit 9. The lock unit 32 includes an engaging portion 36 that engages with the connecting member 20, a spring portion 37 that biases the engaging portion 36 toward the front caster MC, and a guide portion 38 that guides the movement of the engaging portion 36.

[0029] The engaging portion 36 is movable between a first engaging position, a second engaging position, and a retracted position farther from the rotation axis X3 than the first engaging position and the second engaging position, while being guided by the guide portion 38, in a direction approaching and moving away from the rotation axis X3 (front-rear direction in this embodiment). For example, the first engaging position of the engaging portion 36 is the position shown by the solid line in FIG. 2, the second engaging position is the position shown by the solid line in FIG. 3, and the retracted position is the position shown by the dashed line in FIG. 2. At the first engaging position, the engaging portion 36 engages with the rear end edge of the connecting member 20 when the left and right front casters MC are in the first position, and at the second engaging position, the engaging portion 36 engages with the rear end edge of the connecting member 20 when the left and right front casters MC are in the second position. When the engaging portion 36 is in the retracted position, interference between the connecting member 20 and the engaging portion 36 is avoided while the left and right front casters MC are rotating between the first position and the second position.

[0030] As shown in Figures 2 and 3, a recess 36a is formed at the tip of the engagement portion 36, which engages with the rear end edge of the connecting member 20 at the first engagement position and restricts the up and down movement of the rear end edge. A downward surface 36b is formed at the lower tip of the engagement portion 36, which abuts against the rear end edge of the connecting member 20 from above at the second engagement position and restricts the upward movement of the rear end edge. A protruding piece 36c protruding toward the rotation axis X3 is formed above the recess 36a. The protruding piece 36c abuts against the rear end edge of the connecting member 20 at the retracted position, thereby restricting the front caster MC from rotating beyond a preset inclination angle α.

[0031] 6, the spring portion 37 is composed of a coil spring 37a. In a compressed state, the coil spring 37a has an end portion on the rotation axis X3 side fixed to the engagement portion 36 and an opposite end portion fixed to the guide portion 38. Note that the spring portion 37 is not limited to the coil spring 37a, and other springs such as a leaf spring or a disc spring may be used.

[0032] In this embodiment, the guide portion 38 is fixed to the lower surface of the central member 3C of the frame 3, and includes a front guide portion 38a that guides the movement of the engagement portion 36, and a rear guide portion 38b that supports the rear end of the coil spring 37a. The front end of the coil spring 37a is engaged with a step portion (not shown) that is formed between the front portion of the engagement portion 36 and the shaft portion that extends rearward from the front portion.

[0033] The transmission unit 33 includes a cable 33a and a guide tube 33b through which the cable 33a is inserted. One end of the cable 33a is connected to the lever 34, and the other end of the cable 33a is connected to the engagement unit 36. A tension is always applied to the cable 33a by the biasing force of the coil spring 37a. One end of the guide tube 33b is fixed to a bracket 35 of the lever 34, and the other end is fixed to the central member 3C via a bracket 39.

[0034] In the rotation lock mechanism 30, when a user grips the lever 34, the operating force of the lever 34 is transmitted to the engagement portion 36 via the cable 33a, and the engagement portion 36 moves from the first engagement position or the second engagement position to the retracted position against the biasing force of the coil spring 37a. When the operating force of the lever 34 is released, the engagement portion 36 moves from the retracted position to the first engagement position or the second engagement position due to the biasing force of the coil spring 37a.

[0035] The operation for switching the front caster MC from the omnidirectional traveling mode to the straight traveling mode is as follows. First, the lever 34 of the rotation lock mechanism 30 is gripped, the engaging portion 36 is moved to the retracted position, and the engagement between the engaging portion 36 and the connecting member 20 of the front caster MC in the first position is released. In this state, the cart T1 is moved forward (the front caster MC is moved in the direction from the rotation axis X3 toward the swivel axis X2), and the road surface reaction force and rolling resistance input to the wheel 11 rotate the front caster MC from the first position to the second position. Next, the operating force of the lever 34 is released, and the engaging portion 36 is moved to the second engaging position to engage with the connecting member 20, and the front caster MC is held in the second position. This operation switches the traveling mode of the front caster MC from the omnidirectional traveling mode to the straight traveling mode.

[0036] The operation of switching the front caster MC from the straight running mode to the omnidirectional running mode is as follows. First, the lever 34 is gripped, and the engaging portion 36 is moved to the retracted position, and the engagement between the engaging portion 36 and the connecting member 20 of the front caster MC in the second position is released. In this state, the cart T1 is moved backward (the front caster MC is moved in the direction from the pivot axis X2 toward the pivot axis X3), and a lateral load having a forward component that occurs when the orientation of the wheel 11 is shifted in a direction intersecting the front-rear direction is applied to the wheel 11. Then, the front caster MC is rotated from the second position to the first position by the moment of this lateral load. Next, the operating force of the lever 34 is released, and the engaging portion 36 is moved to the first engaging position to engage with the connecting member 20, and the front caster MC is held in the first position. This operation allows the running mode of the front caster MC to be switched from the straight running mode to the omnidirectional running mode.

[0037] The following describes the effects of the front caster MC and the trolley T1.

[0038] (1) The front caster MC, which is a movable swivel caster MC, includes a wheel 11 and a swivel fitting 12 that supports the wheel 11 rotatably around a rotation axis X1 and that is rotatable around a rotation axis X2 that is perpendicular to a straight line parallel to the rotation axis X1 and does not intersect with the rotation axis X1. The front caster MC is rotatable around a rotation axis X3 between a first position where the loading platform 1 is supported with the rotation axis X2 extending in the vertical direction, and a second position where the loading platform 1 is supported with the rotation axis X2 tilted. The rotation axis X2 in the second position is tilted at an inclination angle α so that the lower part of the rotation axis X2 is located closer to the rotation axis X3 than the rotation axis X2 in the first position. The distance D1 between the rotation axis X1 and the pivot axis X2, the distance D2 between the rotation axis X3 and the pivot axis X2, and the distance D3 between the rotation axis X1 and the pivot axis X3 in the axial direction of the pivot axis X2 satisfy formulas (1) and (2). D1 ≧ D2 > 0 (1) D1 + D2 ≧ D3 × tan α (2)

[0039] The front caster MC satisfies formula (1), so as described above, by simply moving the front caster MC in the direction from the pivot axis X3 toward the swivel axis X2 (moving the trolley T1 forward), the travel mode switches to the straight-line travel mode, making it possible to achieve straight-line travel. Also, since formula (2) is satisfied, as described above, by simply moving the front caster MC in the direction from the pivot axis X2 toward the pivot axis X3 (moving the trolley T1 backward), the travel mode switches to the omnidirectional travel mode, making it possible to easily travel in any horizontal direction. In other words, the front caster MC can switch between the straight-line travel mode and the omnidirectional travel mode by simply moving the front caster MC in the direction from the pivot axis X3 toward the swivel axis X2 or in the opposite direction (moving the trolley T1 forward or backward).

[0040] (2) For the front caster MC, the distances D1 and D2 satisfy the formula (3). D2 ≧ 0.75 × D1 (3)

[0041] That is, according to the front caster MC, the distance D2 is 75% or more and 100% or less of the distance D1, so that the change in height of the loading platform 1 or the change in the posture of the loading surface 1a when the front caster MC rotates between the first position and the second position can be reduced. This makes it possible to switch the travel mode of the front caster MC while preventing the load from falling even when the load is placed on the loading platform 1. In addition, the force required for switching the travel mode (such as the lateral load acting on the wheel 11) can be reduced, so that the travel mode can be switched more reliably by moving the trolley T1 forward and backward. The distance D2 is more preferably 80% or more and 100% or less of the distance D1, and even more preferably 90% or more and 100% or less of the distance D1.

[0042] (3) The left and right front casters MC have their rotation axes X3 on the same straight line, and are connected to each other by the connecting member 20. The connecting member 20 is fixed to the rear part of each front caster MC, that is, to the part located on the opposite side of the rotation axis X2 with the rotation axis X3 in between. Therefore, the center of gravity of the part of the left and right front casters MC that rotates around the rotation axis X3 can be moved rearward (in a direction farther away from the rotation axis X2 on the rotation axis X3 side than the rotation axis X2) than when the connecting member 20 is not present. This makes it possible to more reliably rotate the front caster MC from the second position to the first position. In addition, the connecting member 20 can align the rotation phases of the left and right front casters MC, making it possible to more smoothly switch the running mode of the trolley T1.

[0043] (4) The shaft 17 constituting the rotation axis X3 of the left and right front casters MC is supported by the platform 1 at both ends and at a portion located between the left and right front casters MC. Therefore, the support rigidity of the shaft 17 is high, and the rotational movement of the front casters MC is stable.

[0044] (5) The trolley T1 has a front caster MC, which is a movable swivel caster MC, attached to the front of the platform 1, a rear caster C, which is a fixed swivel caster C, attached to the rear of the platform 1, and a sleeve 2 provided at the rear of the platform 1. For this reason, by setting the front caster MC to a straight running mode and moving the rear caster C provided on the sleeve 2 side in the lateral direction, the traveling direction of the trolley T1 can be changed with a smaller operating force. In addition, by tilting the sleeve 2 backward with the rear caster C as a fulcrum, and reducing the road reaction force input to the wheel 11 of the front caster MC, it is also possible to encourage the front caster MC to rotate from the second position to the first position.

[0045] <Other embodiments> Hereinafter, a cart according to another embodiment will be described with reference to the drawings. In the description of the other embodiment, only the configuration different from the preceding embodiment will be described, and elements having the same functions as elements already described in the preceding embodiment will be given the same reference numerals and their description will be omitted.

[0046] <Second embodiment> 7, in the trolley T2, front casters C which are fixed swivel casters C are attached to the front of the platform 1, rear casters MC which are movable swivel casters MC are attached to the rear of the platform 1, and sleeves 2 are provided at the rear of the platform 1. Each rear caster MC is attached to the platform 1 such that the swivel axis X2 is located forward of the rotation axis X3 when the rear caster MC is in the first position.

[0047] (6) In the case of the trolley T2, when the rear casters MC rotate from the first position to the second position, the platform 1 tilts slightly backward, and the loading surface 1a tilts so that the rear side is lower than the front side. Therefore, according to the trolley T2, by setting the rear casters MC to the second position, the luggage placed on the platform 1 can be supported from behind while being in contact with the front surface of the sleeve 2 and transported. In addition, at this time, the rear casters MC are in the straight-line travel mode, and the lateral movement of the rear part of the platform 1 is restricted, so that the application of lateral acceleration to the luggage in contact with the sleeve 2 is suppressed. This allows the luggage to be transported stably while preventing the luggage from collapsing.

[0048] <Third embodiment> Although not shown, in the dolly T3 according to the third embodiment, movable swivel casters MC are attached to the front and rear of the platform 1, and a sleeve 2 is provided at the rear of the platform 1. Each movable swivel caster MC is attached to the platform 1 such that the swivel axis X2 is located forward of the rotation axis X3 when the movable swivel caster MC is in the first position. The rotation axis X3 of the front movable swivel caster MC is parallel to the rotation axis X3 of the rear movable swivel caster MC. The rotation lock mechanism 30 includes a mechanism for locking the rotation of the front movable swivel caster MC and a mechanism for locking the rotation of the rear movable swivel caster MC.

[0049] In the bogie T3, the front movable swivel caster MC is rotated between the first and second positions while the rear movable swivel caster MC is set to the first position, thereby obtaining the same effect as the bogie T1 of the first embodiment. Also, the rear movable swivel caster MC is rotated between the first and second positions while the front movable swivel caster MC is set to the first position, thereby obtaining the same effect as the bogie T2 of the second embodiment. Furthermore, by setting all the movable swivel casters MC to the second position and entering the straight running mode, the bogie T3 can exhibit higher straight running performance than the bogies T1 and T2 of the first and second embodiments.

[0050] The above-mentioned embodiments are merely examples described to facilitate understanding of the invention. The technical scope of the invention is not limited to the specific technical matters disclosed in the above-mentioned embodiments, but also includes various modifications, changes, alternative techniques, etc. that can be easily derived therefrom.

[0051] In the above embodiment, the bottom of the loading platform 1 is provided with four swivel casters, but the number of swivel casters is not limited to this. The swivel casters may be composed of one or more movable swivel casters MC and two or more fixed swivel casters C. In this case, the two or more fixed swivel casters C are arranged so that the swivel axes X2 of the wheels 11 are aligned on a straight line in a plan view, and the rotation axes X3 of the one or more movable swivel casters MC are arranged so as to be parallel to the straight line. The fixed swivel caster C may also be replaced with a fixed caster. A fixed caster is a caster that does not swivel, and only the wheels rotate around the wheel axis. In this case, the two or more fixed casters are arranged so that the rotation axes of the wheels are aligned on the same straight line, and the rotation axes X3 of the one or more movable swivel casters MC are arranged parallel to the rotation axes of the wheels of the fixed casters.

[0052] The swivel caster may also be composed of two or more movable swivel casters MC and one fixed swivel caster C. The fixed swivel caster C may be replaced with a fixed caster. In this case, the rotation axis X3 of the two or more movable swivel casters MC may be arranged parallel to the rotation axis of the wheel of the fixed caster.

[0053] In the above embodiment, the sleeve 2 is provided at the rear of the loading platform 1, but the sleeve 2 may be provided at the front of the loading platform 1, or at both the front and rear. Alternatively or in addition, the sleeve 2 may be provided on either the left or right side or both of the loading platform 1. Furthermore, the loading platform 1 may be provided with a box, a shelf with multiple loading surfaces, etc., depending on the shape, weight, characteristics, etc. of the luggage. [Explanation of symbols]

[0054] T1, T2 trolley 1 Cargo platform MC Movable swivel casters: front casters and rear casters 11 wheels 12 Swivel bracket X1 Rotation Axis X2 Pivot Axis X3 Rotation Axis 20 Connecting members 17 Shaft 2 Sleeves C Fixed swivel casters: front casters and rear casters

Claims

1. A movable swivel caster attached to the platform of a cart, Wheels and a swivel fitting that supports the wheel rotatably around a rotation axis and is rotatable around a rotation axis that is perpendicular to a line parallel to the rotation axis and does not intersect with the rotation axis; Equipped with The platform is rotatable about a rotation axis between a first position in which the platform is supported with the rotation axis extending in a vertical direction and a second position in which the platform is supported with the rotation axis inclined, The pivot shaft in the second position is inclined at an inclination angle α so that a lower portion of the pivot shaft is located closer to the pivot shaft than the pivot shaft in the first position, A movable swivel caster, wherein a distance D1 between the rotation axis and the swivel axis, a distance D2 between the rotation axis and the swivel axis, and a distance D3 between the rotation axis and the swivel axis in the axial direction of the swivel axis satisfy formula (1) and formula (2). D1 ≧ D2 > 0 ... (1) D1+D2≧D3×tanα...(2)

2. The movable swivel caster according to claim 1 , wherein the distance D1 and the distance D2 satisfy formula (3). D2≧0.75×D1 (3)

3. 3. A movable swivel caster according to claim 1 or 2, wherein the rotation axes are on the same straight line and connected to each other by a connecting member, A movable swivel caster, wherein the connecting member is fixed to a portion of each of the movable swivel casters that is located on the opposite side of the swivel shaft across the swivel shaft.

4. A plurality of movable swivel casters according to claim 1 or 2; A shaft that constitutes the rotation axis of the plurality of movable swivel casters; Equipped with A cart in which the shaft is supported by the platform at both ends and at a portion located between the plurality of movable swivel casters.

5. A trolley comprising: a movable swivel caster as described in claim 1 or 2, attached to the front of the loading platform so that the swivel axis is located forward of the rotation axis when the movable swivel caster is in the first position; a fixed swivel caster is attached to the rear of the loading platform; and a sleeve is provided at the rear of the loading platform.

6. A trolley comprising: a fixed swivel caster attached to the front of the loading platform; a movable swivel caster as described in claim 1 or 2 attached to the rear of the loading platform so that the swivel axis is located forward of the rotation axis when the movable swivel caster is in the first position; and a sleeve provided at the rear of the loading platform.

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