Cart

Abstract

To readily solve a problem that a cart deviates from a travel route.SOLUTION: A cart 1 includes a cargo bed 2 on which a cargo is placed, a front travel machine 3 and rear travel machine 4 which are attached to an undersurface 2A of the cargo bed so that they can swivel, and a coupling bar 5 that diagonally couples the front travel machine and rear travel machine. The length of the coupling bar is adjustable with the coupling bar left attached.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a dolly. [Background technology]

[0002] Trucks are used to transport cargo in factories and other places. Multiple trucks are often connected together and towed by a towing vehicle to transport a large amount of cargo at once. Some trucks are equipped with four-wheel steering to enable them to navigate curved routes without straying from the road. These trucks include a platform for carrying cargo, front and rear running wheels rotatably attached to the underside of the platform, and a connecting rod that diagonally connects the front and rear running wheels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-77388 Summary of the Invention [Problem to be solved by the invention]

[0004] When a relatively large number of such four-wheel steering bogies are connected together and towed in a straight line, the rear bogies may deviate from the travel route. To solve this problem, the connecting rods of the rear bogies are replaced with ones of different lengths. However, replacing the connecting rods does not necessarily solve the problem, and further replacement may be necessary. Furthermore, the direction and amount of deviation varies depending on the usage conditions, making it difficult to determine a uniform length for the connecting rods. Of course, replacing the connecting rods on site is not easy and is complicated.

[0005] The present disclosure has been devised in light of the above circumstances, and its purpose is to provide a bogie that can easily solve the problem of the bogie deviating from its travel route. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, A loading platform for carrying luggage, a front running mechanism and a rear running mechanism rotatably attached to the underside of the loading platform; a connecting rod diagonally connecting the front running unit and the rear running unit; Equipped with The connecting rod is configured so that its length can be adjusted while it is attached. A carriage characterized by the above features is provided.

[0007] Preferably, the connecting rod is constituted by a turnbuckle.

[0008] Preferably, the connecting rod is a rod body extending linearly; a right-handed threaded shaft that is threadably attached to one end of the rod body; a left-handed threaded shaft that is threadably attached to the other end of the rod body; Equipped with.

[0009] Preferably, the rod body has A hollow pipe, a right-hand thread nut and a left-hand thread nut fixed to one end and the other end of the hollow pipe, respectively; It has.

[0010] Preferably, the rod body has a jig insertion hole into which a jig is inserted when the rod body is rotated.

[0011] Preferably, the connecting rod is lock nuts for fixing the right-hand threaded shaft and the left-hand threaded shaft to the rod main body, respectively; Coupling members fixed to the right-hand threaded shaft and the left-hand threaded shaft, respectively; Equipped with.

[0012] Preferably, the lock nuts are threadedly engaged with the right-hand threaded shaft and the left-hand threaded shaft, respectively.

[0013] Preferably, the joint member is formed by a joint plate that is sandwiched and fixed between the right-hand threaded shaft and the left-hand threaded shaft, The front traveling unit and the rear traveling unit have a pair of clamping plates that sandwich the joint plate, The joint plate and the clamping plate have a connecting shaft insertion hole, When a connecting shaft is inserted into the connecting shaft insertion hole, the joint plate is rotatably connected to the clamping plate.

[0014] Preferably, the front running mechanism has a front connection portion for connecting the connecting rod to one of the right and left sides of the rear end portion thereof, The rear running mechanism has a rear connecting portion at the other of the right and left sides at its front end portion for connecting the connecting rod.

[0015] Preferably, the loading platform has a front pivot shaft and a rear pivot shaft protruding from a lower surface thereof, The front and rear travellers have front and rear swivel holes into which the front and rear swivel shafts are rotatably inserted, respectively.

[0016] Preferably, the front running unit has a traction member extending forward, The loading platform has an engaging portion with which the towing member of a following carriage is engaged. [Effects of the Invention]

[0017] According to the present disclosure, the problem of the carriage deviating from the travel route can be easily solved. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a plan view showing the bogie according to the present embodiment. [Figure 2] FIG. 2 is a side view showing the bogie according to the present embodiment. [Figure 3] FIG. [Figure 4] FIG. [Figure 5]FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. 10 is a side view showing the connection between the connecting rod and the front running mechanism. [Figure 12] FIG. 10 is a plan view for explaining the operation of the carriage. [Figure 13] FIG. 10 is a plan view showing the coupled state of the carriages. [Figure 14] FIG. 10 is a plan view for explaining the cause of the problem. [Figure 15] FIG. 10 is a plan view showing how the length of the connecting rod is adjusted. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to the following embodiments.

[0020] 1 and 2 are a plan view and a side view showing the entire bogie according to this embodiment. The front, rear, left, right, top and bottom directions of the bogie 1 are as shown in the figures. A plurality of bogies 1 can be connected together and are capable of four-wheel steering (4WS).

[0021] The carriage 1 comprises a loading platform 2 for carrying luggage, a front running unit 3 and a rear running unit 4 rotatably attached to the underside 2A of the loading platform 2, and a connecting rod 5 that diagonally connects the front running unit 3 and the rear running unit 4. The connecting rod 5 of this embodiment is characterized in that its length can be adjusted while it is attached.

[0022] 3 and 4 are a plan view and a side view showing the loading platform 2 alone. The loading platform 2 is constructed by assembling ordinary steel materials (such as L-shaped steel beams), steel pipe materials (such as square pipes), steel plates, etc., by welding. The loading platform 2 is formed symmetrically from front to back and from left to right. The cargo that can be placed on the loading platform 2 is, for example, a plastic or metal pallet carrying products.

[0023] The loading platform 2 is formed in a quadrilateral, particularly a square, shape in a plan view (Fig. 3). The loading platform 2 has a loading platform frame 6 formed in a rectangular frame shape in a plan view, and support plates 7 provided on the upper surface of the four corners of the loading platform frame 6, front, rear, left, and right, on which cargo is placed. The loading platform 2 also has regulating plates 8 provided on the four corners of the loading platform frame 6, front, rear, left, and right. The regulating plates 8 protrude slightly upward from the support plates 7, and catch on cargo that attempts to slide off the support plates 7, preventing it from sliding off. The regulating plates 8 are formed in an L-shape in a plan view, and are attached to the front, rear, left, and right side surfaces of the loading platform frame 6.

[0024] The loading platform 2 has a front pivot shaft 9 and a rear pivot shaft 10 that protrude downward from its underside 2A. The front pivot shaft 9 and the rear pivot shaft 10 are formed by solid shafts with circular cross sections that extend in the vertical direction, and are fixed to the front fixed plate 9A and the rear fixed plate 10A of the loading platform frame 6, respectively, in a state in which they penetrate through them. The front pivot shaft 9 and the rear pivot shaft 10 are positioned in the center of the left-right width of the loading platform 2, and are spaced apart in the front-to-rear direction. The front pivot shaft 9 and the rear pivot shaft 10 are parts to which the front running unit 3 and the rear running unit 4 are respectively attached so that they can pivot. Note that "turning" refers to rotation around an axis that extends in the vertical direction (a vertical axis or a longitudinal axis).

[0025] A front rolling plate 11 and a rear rolling plate 12 are provided on the underside 2A of the loading platform 2, with which support bearings 34 (see FIGS. 5 to 8) of the front running unit 3 and the rear running unit 4, which will be described later, come into contact and roll. The front rolling plate 11 and the rear rolling plate 12 are affixed to the underside of the loading platform frame 6 at positions around the front pivot shaft 9 and the rear pivot shaft 10. The front pivot shaft 9 and the rear pivot shaft 10 protrude downward beyond the front rolling plate 11 and the rear rolling plate 12.

[0026] The loading platform 2 has an engagement portion 13 on its rear surface 2B with which a towing member (described later) of the following carriage 1 engages. The engagement portion 13 is attached to the rear surface of the loading platform frame 6 and has an engagement member 14 that is U-shaped in side view (Fig. 4), a pin insertion hole 15 that passes vertically through the engagement member 14, and an engagement pin 16 that is inserted into the pin insertion hole 15 from above. A cushioning material 17 made of an elastic material such as rubber is affixed to the inner surface of the engagement member 14 to prevent direct collision with the towing member. The engagement pin 16 has a circular cross section and is provided with a larger-diameter handle 18 at its upper end.

[0027] 5 and 6 are a plan view and a side view showing the front running unit 3 alone. Since the front running unit 3 and the rear running unit 4 are configured in almost the same way, only the front running unit 3 will be described in detail, and the rear running unit 4 will be described in a supplementary manner, focusing only on the differences.

[0028] The front running unit 3 has a frame 20 extending in the left-right direction, and left and right casters 21, 22 attached to the underside of the frame 20. The frame 20 is formed in the shape of a rectangular frame whose width in the left-right direction is greater than its length in the front-to-rear direction in a plan view (FIG. 5). The left and right casters 21, 22 are attached to the underside of the left and right ends of the frame 20. These casters 21, 22 are similar, so only the right caster 22 will be described in detail below.

[0029] The caster 22 has a rotatable wheel 23. The caster 22 of this embodiment is formed as a fixed caster in which the wheel 23 does not rotate (i.e., does not swivel) around a vertical axis or a longitudinal axis.

[0030] The caster 22 has a base plate 26 fixed to the underside of the frame 20 by multiple (four) bolts 24 and nuts 25, a support leg 27 fixed to the base plate 26 and extending downward in a bifurcated shape, a suspension arm 29 sandwiched between the support legs 27 and attached by bolts 28 so as to be rotatable around a left-right axis (an axis extending in the left-right direction), a wheel 23 attached to the rear end of the suspension arm 29 by bolts 30 so as to be rotatable around the left-right axis, and a suspension spring 31 that urges the front end of the suspension arm 29 upward so as to press the wheel 23 against the road surface.

[0031] The front running mechanism 3 has a front swivel hole 32 into which the front swivel shaft 9 is rotatably inserted. The front swivel hole 32 is formed by a central hole in a center bearing 33 provided at the center of the front-to-rear length and left-to-right width of the frame 20. The center bearing 33 is formed by a ball bearing. A front thrust surface 32A is formed around the center bearing 33 and receives the main downward thrust load from the front fixed plate 9A of the loading platform 2. After assembly, the front thrust surface 32A comes into slidable contact with the front fixed plate 9A.

[0032] The front running mechanism 3 also has a plurality of (six) support bearings 34 arranged around the front swivel hole 32 and therefore the front fixed plate 9A to auxiliarily support the load of the loading platform 2. The support bearings 34 are also formed of ball bearings. The support bearings 34 are rotatably mounted on the frame 20, one each in front and behind the center bearing 33, and two each on the left and right. The front and rear support bearings 34 are rotatable around a front-to-rear axis, and the left and right support bearings 34 are rotatable around a left-to-right axis. These support bearings 34 are arranged symmetrically in the front-to-rear and left-to-right directions with respect to the position of the front swivel hole 32. As can be seen in FIG. 6, these support bearings 34 protrude slightly upward from the frame 20.

[0033] To tow the bogie 1, the front running unit 3 has a towing member 35 extending forward. The towing member 35 has a towing frame 36 that is fixed to the front portion of the frame 20 and has a U-shape in plan view, and a towing hook 38 that is rotatably attached to the front end of the towing frame 36 by a towing shaft 37. The towing hook 38 is rotatable about its left and right axis and is formed in a triangular shape in plan view as shown in FIG. 5. A pin insertion hole 38A is provided at the front end of the towing hook 38. A handle 39 is provided on the towing hook 38 for manually raising and lowering or lowering the towing hook 38.

[0034] The front running mechanism 3 has a front connection part 40 on the right side of its rear end for connecting the front end of the aforementioned connecting rod 5. The front connection part 40 has a pair of upper and lower clamping plates 41 fixed to the right side of the rear surface of the frame 20, and a connecting shaft insertion hole 42 formed in the clamping plates 41 so as to penetrate vertically.

[0035] Next, the rear running unit 4 will be described in more detail with reference to Figures 7 and 8. Here, parts that are the same as those on the front running unit 3 will be given the same reference numerals in the figures, with some exceptions, and their description will be omitted. Furthermore, the "front side" included in the names of the parts on the front running unit 3 will be replaced with the "rear side" for the rear running unit 4.

[0036] The rear running mechanism 4 has a rear swivel hole 43 into which the rear swivel shaft 10 is rotatably inserted. This rear swivel hole 43 is also formed by the center bearing 33, which is a ball bearing. A rear thrust surface 43A is formed around this center bearing 33 and receives the main downward thrust load from the rear fixed plate 10A of the cargo bed 2. After assembly, the rear thrust surface 43A comes into slidable contact with the rear fixed plate 10A.

[0037] The rear running unit 4 has a rear connecting part 44 on the left side of its front end for connecting the rear end of the connecting rod 5. Similar to the front connecting part 40, the rear connecting part 44 also has a pair of clamping plates 41 and a connecting shaft insertion hole 42.

[0038] The rear running unit 4 is not provided with a traction member 35.

[0039] 9 and 10 are a plan view and a side view showing the connecting rod 5 alone. The symbol C represents the central axis of the connecting rod 5. Unless otherwise specified, the axial direction, radial direction, and circumferential direction based on the central axis C will be simply referred to as the axial direction, radial direction, and circumferential direction below.

[0040] For convenience, one axial end located on the right side in the drawing is referred to as the front side, and the other axial end located on the left side in the drawing is referred to as the rear side.

[0041] With some exceptions, the connecting rods 5 are configured symmetrically in the front and rear directions.

[0042] As described above, the connecting rod 5 is configured so that its length can be adjusted while it is in an attached state. More specifically, the connecting rod 5 is configured as a turnbuckle. The connecting rod 5 comprises a rod body 51 extending linearly in the axial direction, a right-handed threaded shaft 52 that is threadedly attached to the front end (one end) of the rod body 51, and a left-handed threaded shaft 53 that is threadedly attached to the rear end (other end) of the rod body 51. In other words, the connecting rod 5 has reverse threads at both ends of the rod body 51. The rod body 51, the right-handed threaded shaft 52, and the left-handed threaded shaft 53 are arranged coaxially with the central axis C.

[0043] As is well known, a right-hand thread is a thread that advances toward the mating thread when turned to the right, and a left-hand thread is a thread that advances toward the mating thread when turned to the left.

[0044] The rod body 51 has a hollow pipe 54 that forms its basic part, and a right-hand thread nut 55 and a left-hand thread nut 56 that are fixed to the front and rear ends of the hollow pipe 54, respectively. The hollow pipe 54 is formed from a steel pipe with a circular cross section. The right-hand thread nut 55 and the left-hand thread nut 56 are coaxially arranged on the front and rear end faces of the hollow pipe 54 with plate rings 55A and 56A sandwiched between them, and are fixed by welding.

[0045] As will be described in detail later, the rod body 51 is rotated when adjusting the length of the connecting rod 5. To facilitate this rotation of the rod body 51, jig insertion holes 57 into which a jig or tool is inserted are provided in the rod body 51. The jig insertion holes 57 are formed by circular holes provided on the front and rear sides of the hollow pipe 54 and passing radially through the hollow pipe 54.

[0046] In the axial direction of the connecting rod 5, the direction toward the longitudinal center C1 of the rod main body 51 is referred to as the axial inner side, and the direction away from the longitudinal center C1 of the connecting rod 5 is referred to as the axial outer side. The longitudinal center C1 of the rod main body 51 refers to the position that divides the length of the rod main body 51 into two equal parts.

[0047] The base ends of the right-hand threaded shaft 52 and the left-hand threaded shaft 53, which are located axially inside, are threadedly engaged with the right-hand threaded nut 55 and the left-hand threaded nut 56 and inserted into the hollow pipe 54. On the other hand, the remaining or tip-side portions of the right-hand threaded shaft 52 and the left-hand threaded shaft 53, which are located axially outside the right-hand threaded nut 55 and the left-hand threaded nut 56, are not inserted into the hollow pipe 54 and are exposed to the outside.

[0048] Lock nuts 58, 59 and coupling members 60, 61 are attached to this tip end portion. The lock nuts 58, 59 are used to secure the right-hand threaded shaft 52 and the left-hand threaded shaft 53 to the rod main body 51, and are threadedly engaged with the right-hand threaded shaft 52 and the left-hand threaded shaft 53, respectively. The coupling members 60, 61 are used to connect the connecting rod 5 to the front connecting part 40 and the rear connecting part 44, respectively, and are fixed to the right-hand threaded shaft 52 and the left-hand threaded shaft 53.

[0049] Naturally, the lock nut 58 threaded onto the right-handed screw shaft 52 has a right-handed internal thread, and the lock nut 59 threaded onto the left-handed screw shaft 53 has a left-handed internal thread.

[0050] In this embodiment, a flat washer 58A and a spring washer 58B are attached between the lock nut 58 and the right-hand thread nut 55. A flat washer 59A and a spring washer 59B are attached between the lock nut 59 and the left-hand thread nut 56. However, at least one of the flat washer and the spring washer may be omitted.

[0051] For example, when fixing the right-hand threaded shaft 52 to the rod body 51, the lock nut 58 on the right-hand threaded shaft 52 is rotated clockwise and tightened toward the right-hand threaded nut 55. This locks the rotation of the right-hand threaded shaft 52 relative to the rod body 51, and fixes the right-hand threaded shaft 52 so that it cannot move relative to the rod body 51. The same is true for the left-hand threaded shaft 53, except that the rotation direction of the lock nut 59 is reversed.

[0052] In this embodiment, the lock nut 58 is configured as a nut with a locking function, such as a U-nut or nylon nut. This prevents the lock nut 58 from loosening. On the other hand, the right-hand thread nut 55 and the left-hand thread nut 56 are configured as general-purpose nuts without a locking function. This means that the locking function does not provide resistance when adjusting the length, allowing the rod body 51 to rotate smoothly.

[0053] The joint members 60, 61 are formed by joint plates 62, 63 that are sandwiched and fixed between the right-handed threaded shaft 52 and the left-handed threaded shaft 53, respectively. The joint plates 62, 63 are formed in a rectangular shape with a front-to-rear length greater than a left-to-right width in a plan view ( FIG. 9 ). The axially inner base ends of the joint plates 62, 63 are inserted into slits 64, 65 formed in the axially outer tip surfaces of the right-handed threaded shaft 52 and the left-handed threaded shaft 53, and are welded to the right-handed threaded shaft 52 and the left-handed threaded shaft 53. Connecting shaft insertion holes 66, 67 are formed in the axially outer tip ends of the joint plates 62, 63.

[0054] Next, a method for assembling the carriage 1 will be described.

[0055] First, prepare a connecting rod 5 whose length has been adjusted to a predetermined reference length L0 (e.g., 1000 mm). At this time, as shown in Figure 9, the distance between the front and rear connecting shaft insertion holes 66, 67 is defined as the length L of the connecting rod 5, and this length L is set to the reference length L0. The length adjustment method will be described in detail later, but in this embodiment, the length can be adjusted very conveniently by simply rotating the rod body 51 while restricting the rotation of the right-hand threaded shaft 52 and the left-hand threaded shaft 53. The lock nuts 58, 59 are tightened, and the length of the connecting rod 5 is fixed to the reference length L0.

[0056] Next, the front and rear ends of the connecting rod 5 are connected to the front running unit 3 and the rear running unit 4, respectively. Taking the front side as an example, as shown in FIG. 11 , the front joint member 60 of the connecting rod 5, i.e., the joint plate 62, is inserted between the pair of clamping plates 41 at the front connection portion 40 of the front running unit 3. Then, a connecting bolt 68 forming a connecting shaft is inserted from above into the connecting shaft insertion holes 42, 66 of the clamping plate 41 and the joint plate 62. A lock nut 70 with an anti-loosening function is tightened onto the threaded portion 69 of the connecting bolt 68 protruding downward to prevent the connecting bolt 68 from coming loose. As a result, the joint plate 62 is connected to the clamping plate 41, i.e., the front end of the connecting rod 5 is connected to the front running unit 3, so that it can rotate or swing about the vertical axis.

[0057] The same is true for the rear side. Referring to Figures 7 to 10, the rear joint member 61 of the connecting rod 5, i.e., the joint plate 63, is inserted between the pair of clamping plates 41 at the rear connection portion 44 of the rear rung 4. Then, a connecting bolt 68 forming a connecting shaft is inserted from above into the connecting shaft insertion holes 42, 67 of the clamping plate 41 and the joint plate 63. A lock nut 70 with an anti-loosening function is tightened onto the threaded portion 69 of the connecting bolt 68 protruding downward to prevent the connecting bolt 68 from coming loose. In this way, the joint plate 63 is connected to the clamping plate 41, i.e., the rear end of the connecting rod 5 is connected to the rear rung 4 so as to be rotatable or pivotable about the vertical axis.

[0058] When the connecting rod 5 is connected to the front and rear running units 3 and 4 in this manner, the front and rear running units 3 and 4 are diagonally connected by the connecting rod 5 in a plan view, as shown in Fig. 1. Here, "diagonally connected" means that one of the right and left sides of the front running unit 3 is connected to the other of the right and left sides of the rear running unit 4, and the connecting rod 5 is arranged in a state inclined relative to the front-to-rear direction in a plan view. In this embodiment, the right side of the front running unit 3 is connected to the left side of the rear running unit 4, but this may be reversed.

[0059] Next, as shown in Figures 1 and 2, the loading platform 2 is placed on the front running unit 3 and the rear running unit 4. At this time, the front swivel shaft 9 and the rear swivel shaft 10 of the loading platform 2 are rotatably inserted from above into the front swivel hole 32 (center bearing 33) of the front running unit 3 and the rear swivel hole 43 (center bearing 33) of the rear running unit 4, respectively. As a result, the front fixing plate 9A of the loading platform 2 comes into slidable contact with the front thrust surface 32A of the front running unit 3, and the rear fixing plate 10A of the loading platform 2 comes into slidable contact with the rear thrust surface 43A of the rear running unit 4. The main downward load of the loading platform 2 is then supported by the front running unit 3 and the rear running unit 4.

[0060] At the same time, the front rolling plates 11 and rear rolling plates 12 of the loading platform 2 approach or come into contact with the support bearings 34 of the front running unit 3 and rear running unit 4. When the front pivot shafts 9 and rear pivot shafts 10 of the loading platform 2 are inserted into the front pivot holes 32 of the front running unit 3 and the rear pivot holes 43 of the rear running unit 4 and the loading platform 2 is placed on the platform, a small gap is formed between the front rolling plates 11 and rear rolling plates 12 and the support bearings 34, preventing the front rolling plates 11 and rear rolling plates 12 from coming into contact with the support bearings 34. However, in reality, the loading platform 2 tilts slightly relative to the horizontal when placed on the platform due to play, weight imbalance, and the like. At this time, the support bearings 34 located in the tilted direction come into contact with the front rolling plates 11 and / or rear rolling plates 12, thereby supplementarily supporting the weight of the loading platform 2.

[0061] Once the loading platform 2 is placed in this manner, the dolly 1 is completed. By pulling the towing hook 38 of the towing member 35 with a towing vehicle or by hand, the dolly 1 can be towed forward.

[0062] As shown in FIG. 2, when the bogies 1 are coupled, the towing member 35 of the trailing bogie on the left side (rear side) outside the illustration is engaged with the engagement portion 13 of the bogie 1 shown in the illustration. At this time, the front end of the towing hook 38 of the trailing bogie is inserted into the inside of the engagement member 14 of the bogie 1, and the engagement pin 16 is inserted from above into the pin insertion hole 15 of the engagement member 14 and the pin insertion hole 38A of the towing hook 38 (see FIGS. 3 to 6). As a result, the towing member 35 engages with the engagement portion 13, and the bogies 1 are coupled. A buffer material 17 is provided on the inner surface of the engagement member 14, so that damage due to a direct collision between the towing hook 38 and the engagement member 14 can be prevented. The engagement pin 16 is formed to be rather long, so that it is prevented from coming out by its own weight even after it is simply inserted.

[0063] Next, the operation of the cart 1 will be described with reference to Figure 12. For convenience, the platform 2 is omitted from the cart 1 shown in the figure.

[0064] Fig. 12(A) shows the bogie 1 traveling straight, with the bogie 1 being pulled from the front by a tractive force F1 and traveling straight forward. At this time, the direction D1 of the front running unit 3 and the direction D2 of the rear running unit 4 are both forward facing and are the same. The front running unit 3 traveling straight forward pulls the rear running unit 4 via the connecting rod 5, causing the rear running unit 4 to travel straight forward. This allows the bogie 1 to travel smoothly along the linear track R1 extending in the fore-and-aft direction.

[0065] Figure 12(B) shows the time of turning left. At this time, the bogie 1 is pulled from the front left by a tractive force F2, and turns toward the front left. At this time, the direction D1 of the front running unit 3 faces the front left. Then, the right side of the front running unit 3 pulls the left side of the rear running unit 4 via the connecting rod 5, so the direction D2 of the rear running unit 4 faces the front right. In other words, the front running unit 3 and the rear running unit 4 are steered so that they face in opposite directions, thereby achieving four-wheel steering in opposite phases. As a result, the front running unit 3 and the rear running unit 4 can turn smoothly along the curved trajectory R2 that curves to the left.

[0066] Figure 12(C) shows the state when turning right. At this time, the bogie 1 is pulled from the right front by a tractive force F3, causing it to turn toward the right front. At this time, the direction D1 of the front running unit 3 faces right front. Then, the right side of the front running unit 3 pushes the left side of the rear running unit 4 via the connecting rod 5, causing the direction D2 of the rear running unit 4 to face left front. The front running unit 3 and the rear running unit 4 are then steered so that they face in opposite directions, achieving four-wheel steering in opposite phases. This allows the front running unit 3 and the rear running unit 4 to turn smoothly along the curved track R3 that curves to the right.

[0067] When the carriage 1 turns, the front running unit 3 and the rear running unit 4 turn around the front turning shaft 9 and the rear turning shaft 10 relative to the loading platform 2. At this time, the front thrust surface 32A of the front running unit 3 slides in the turning direction on the front fixed plate 9A of the loading platform 2, and the rear thrust surface 43A of the rear running unit 4 slides in the turning direction on the rear fixed plate 10A of the loading platform 2.

[0068] Additionally, the support bearings 34 of the front and rear running units 3 and 4 roll in the turning direction along the undersides of the front and rear rolling plates 11 and 12 of the loading platform 2. This allows the front and rear running units 3 and 4 to turn smoothly while the load of the loading platform 2 is supported by the support bearings 34.

[0069] As mentioned above, when a relatively large number of four-wheel steering bogies are coupled together and towed in a straight line, the rear bogie may deviate from the travel route. To solve this problem, the connecting rods of the rear bogies are replaced with ones of different lengths. However, replacing the connecting rods does not necessarily solve the problem, and further replacement may be necessary. Furthermore, the direction and amount of deviation varies depending on the usage conditions, making it difficult to determine a uniform length for the connecting rods. Of course, replacing the connecting rods on site is not easy and is complicated.

[0070] This problem will be explained in detail below. Figure 13 shows a case where a relatively large number of bogies 1 of this embodiment are coupled together. In this embodiment, seven bogies 1 are coupled together, and the bogies 1 are numbered, from the front, as car No. 1 (#1), car No. 2 (#2), to car No. 7 (#7). A test was conducted in which the leading car No. 1 was pulled by a towing vehicle, and the seven coupled bogies 1 in total were driven straight ahead.

[0071] The test results showed that the rear bogie 1 (for example, cars 5 to 7) had a problem with deviating from the running route. In other words, there was no problem when the number of cars connected was small, but problems tended to occur when the number of cars connected was large.

[0072] Even if the deviation from the driving route of one vehicle is small, when two, three, etc. vehicles are connected, the deviation accumulates and becomes larger the further back the vehicle is. This is one of the causes of problems when many vehicles are connected.

[0073] 14 is a diagram for easily explaining the cause of the problem. Here again, for the sake of convenience, the loading platform 2 is omitted.

[0074] First, Figure 14(A) shows an ideal bogie 1 in which no misalignment occurs. When this bogie 1 travels straight, the direction D1 of the front running unit 3 and the direction D2 of the rear running unit 4 are both pointing straight ahead. Therefore, the bogie 1 travels forward accurately and straight along the linear track R1.

[0075] However, due to variations in dimensions between individual units, the carriage 1 is not always in an ideal state, and therefore deviations occur in the carriage 1.

[0076] Figure 14(B) shows a bogie 1 that has a problem of deviating to the right. When this bogie 1 travels straight, the direction D1 of the front running unit 3 faces straight ahead, but the direction D2 of the rear running unit 4 faces to the front right. Therefore, the rear running unit 4 tries to travel towards the front right, and as a result, the bogie as a whole travels straight while deviating to the right from the straight track R1.

[0077] Conversely, Figure 14(C) shows a bogie 1 that has the problem of deviating to the left. When this bogie 1 travels straight, the direction D1 of the front running unit 3 faces straight ahead, but the direction D2 of the rear running unit 4 faces to the front left. Therefore, the rear running unit 4 tries to travel towards the front left, and as a result, the bogie as a whole travels straight while deviating to the left from the straight track R1.

[0078] To solve this problem of misalignment, the connecting rod (shown by reference numeral 5 for convenience) of the bogie 1 is generally replaced with one of a different length. For example, in the case of a bogie 1 that is misaligned to the right as shown in FIG. 14(B), replacing the connecting rod 5 with a longer one will correct the direction D2 of the rear running unit 4 toward the left, making it closer to facing forward. Also, in the case of a bogie 1 that is misaligned to the left as shown in FIG. 14(C), replacing the connecting rod 5 with a shorter one will correct the direction D2 of the rear running unit 4 toward the right, making it closer to facing forward.

[0079] However, replacing the rods does not necessarily solve the problem, and further replacement may be necessary. Furthermore, the direction and amount of misalignment varies depending on the conditions of use, making it difficult to determine a uniform length for the connecting rods. Of course, on-site replacement is not easy and complicated.

[0080] Therefore, in this embodiment, the connecting rod 5 is configured so that its length can be adjusted while it is still attached. This allows the length of the connecting rod 5 to be adjusted while it is still attached, without having to be removed from the bogie 1. Therefore, by adjusting the length of the connecting rod 5, the direction D2 of the rear running unit 4 can be corrected, bringing it closer to facing forward, thereby improving the straightness of the bogie 1. This makes it easy to solve the problem of the bogie 1 deviating from its travel route.

[0081] In particular, as shown in Figure 13, when a relatively large number of bogies 1 are connected, by adjusting the length of the connecting rod 5 of the rear bogie 1 which is likely to deviate from the running route, it is possible to reliably keep all of the bogies 1 within the running route even when the number of connected bogies is large.

[0082] In particular, in this embodiment, the connecting rod 5 is configured by the turnbuckle as described above, which makes it extremely easy to adjust the length of the connecting rod 5.

[0083] As shown in Figures 9 and 10, when adjusting the length of the connecting rod 5, the lock nuts 58, 59 are loosened to allow the right-hand threaded shaft 52 and the left-hand threaded shaft 53 to rotate freely relative to the right-hand threaded nut 55 and the left-hand threaded nut 56. Then, the rod body 51 is rotated. This is very convenient because a rod-shaped jig such as a screwdriver can be inserted into the jig insertion hole 57 of the rod body 51 to rotate it. However, there is no problem with rotating it by hand.

[0084] 1, a rectangular (square) opening 71 is provided in the center of the loading platform 2, which exposes almost the entire connecting rod 5, particularly the lock nuts 58, 59 and the rod body 51. Therefore, the connecting rod 5 can be accessed from above through this opening 71, making it easy to adjust the length of the connecting rod 5.

[0085] As shown in Figure 11, coupling members 60, 61 fixed to the right-hand threaded shaft 52 and the left-hand threaded shaft 53 are connected to the front connecting portion 40 and the rear connecting portion 44 of the front running unit 3 and the rear running unit 4. Therefore, rotation of the right-hand threaded shaft 52 and the left-hand threaded shaft 53 is restricted, and the right-hand threaded shaft 52 and the left-hand threaded shaft 53 do not rotate even when the rod main body 51 is rotated. Therefore, when the rod main body 51 is rotated, the right-hand threaded shaft 52 and the left-hand threaded shaft 53 simultaneously move forward and backward relative to the right-hand threaded nut 55 and the left-hand threaded nut 56. Therefore, the length of the connecting rod 5 can be adjusted extremely easily just by rotating the rod main body 51.

[0086] As shown in Figure 9, for example, suppose rod body 51 is rotated left (counterclockwise) as shown by arrow a when viewed from the front. This results in right-handed (clockwise) rotation of front right-handed threaded shaft 52 into right-handed threaded nut 55 as shown by arrow b. On the other hand, left-handed threaded shaft 53 on the rear side also rotates right-handed (counterclockwise when viewed from the rear) into left-handed threaded nut 56 as shown by arrow c. This shortens the length of connecting rod 5.

[0087] Conversely, if the rod body 51 is rotated clockwise as viewed from the front, the front right-hand screw shaft 52 is rotated relatively counterclockwise, and the rear left-hand screw shaft 53 is also rotated relatively counterclockwise (clockwise as viewed from behind), and the length of the connecting rod 5 is increased.

[0088] Once the length of the connecting rod 5 has been adjusted in this way, the lock nuts 58, 59 are loosened to complete the adjustment. In short, the length of the connecting rod 5 can be adjusted in just three steps: loosening the lock nuts 58, 59, rotating the rod body 51, and loosening the lock nuts 58, 59. This is extremely convenient and ideal for adjustment on site. Even if the problem is not resolved after adjustment, it can be easily adjusted again, eliminating the need for complicated adjustments. In other words, each individual trolley 1 can be set up easily and quickly to suit the usage situation.

[0089] Figure 15 shows how the length of the connecting rod 5 of the bogie 1 of this embodiment is adjusted. Figures 15(A) to (C) all show the state when the bogie 1 is moving straight forward. The left and right boundary lines of the ideal traveling route are indicated by AL and AR. The distance between these boundary lines AL and AR is equal to the left and right width of the bogie 1.

[0090] 15(A) shows the state when the bogie 1 deviates to the left from the travel route. The amount of deviation is relatively large, B1, and it is considered that the length of the connecting rod 5 is too long. For example, the upper limit of the deviation, Bmax, is 50 mm, and the deviation B1 is 60 mm, exceeding the upper limit Bmax.

[0091] Based on this result, the length of the connecting rod 5 is adjusted to be shorter. The result at that time is shown in Figure 15(B). In Figure 15(B), the bogie 1 is deviated to the right from the travel route, but the amount of deviation is smaller, B2 = 30 mm, which is less than the upper limit value Bmax. Therefore, the length of the connecting rod 5 at this time is considered to be roughly appropriate.

[0092] On the other hand, Figure 15(C) shows the result when the length of the connecting rod 5 is shortened too much, based on the result of Figure 15(A). In Figure 15(C), the bogie 1 is relatively significantly deviated to the right from the travel route, and the deviation amount B3 is 75 mm, which exceeds the upper limit value Bmax. Therefore, in this case, it is appropriate to readjust the length of the connecting rod 5 to make it slightly longer, so that the deviation amount is within the upper limit value Bmax.

[0093] The length of the connecting rod 5 in this embodiment is adjustable within a range of ±ΔL (for example, 10 mm) from a reference length L0 (for example, 1000 mm), where ΔL is a predetermined adjustment range.

[0094] Incidentally, if the front-to-rear length of the loading platform 2 is changed and the distance between the front running unit 3 and the rear running unit 4 is changed, it is necessary to prepare a connecting rod 5 with a different reference length L0. Even in this case, in this embodiment, it is only necessary to change to a hollow pipe 54 with a different length, so connecting rods 5 with different dimensions can be easily produced at low cost, thereby increasing versatility.

[0095] Although the embodiments of the present disclosure have been described in detail above, various other embodiments and modifications of the present disclosure are possible.

[0096] (1) For example, the right-handed threaded shaft 52 and the left-handed threaded shaft 53 of the connecting rod 5 may be reversed in position. Accordingly, the right-handed threaded nut 55, the left-handed threaded nut 56, and the lock nuts 58 and 59 may be reversed in position.

[0097] (2) A jig engaging portion for engaging a jig or tool may be provided on the outer periphery of the rod body 51 of the connecting rod 5. For example, a hexagonal portion, a square portion, or a facing portion for engaging a wrench may be provided on the outer periphery of the rod body 51 as the jig engaging portion.

[0098] (3) The rod body 51 of the connecting rod 5 may be configured with a solid shaft and right-handed and left-handed female threads formed by female thread machining on both ends of the solid shaft.

[0099] (4) The arrangement of the front connection portion 40 and the rear connection portion 44 to which the connecting rod 5 is connected may be reversed.

[0100] (5) General-purpose nuts without a locking function may be used as the lock nuts 58, 59. If possible, the lock nuts 58, 59 may be omitted.

[0101] The embodiments of the present disclosure are not limited to the above-described embodiments, and all modifications, applications, and equivalents encompassed within the spirit of the present disclosure as defined by the claims are included in the present disclosure. Therefore, the present disclosure should not be interpreted as being limited, and can be applied to any other technology that falls within the spirit of the present disclosure. [Explanation of symbols]

[0102] 1 cart 2 Cargo bed 2A Bottom part 3 Front traveling device 4 Rear running gear 5 Connecting rod 9 Front pivot 10 Rear pivot 13 Engagement portion 32 Front swivel hole 35 Traction member 40 Front connection part 41 Holding plate 42,46 Connecting shaft insertion hole 43 Rear turning hole 44 Rear connection part 51 Stick body 52 Right-hand screw shaft 53 Left-hand screw shaft 54 Hollow Pipe 55 Right-hand thread nut 56 Left-handed nut 57 Jig insertion hole 58,59 Lock nut 60,61 Joint members 62,63 Joint plate 68 Connecting bolt

Claims

1. A platform for carrying luggage, A front running mechanism and a rear running mechanism rotatably attached to the underside of the platform; A connecting rod that diagonally connects the front running unit and the rear running unit; Equipped with The connecting rod is configured so that its length can be adjusted while it is in an attached state. A trolley characterized by:

2. The connecting rod is constituted by a turnbuckle. The dolly according to claim 1.

3. The connecting rod is A rod body extending linearly; A right-handed threaded shaft that is screwed into one end of the rod body; A left-handed screw shaft screwed to the other end of the rod body; Equipped The dolly according to claim 1.

4. The rod body is A hollow pipe; a right-handed nut and a left-handed nut fixed to one end and the other end of the hollow pipe, respectively; have 4. The trolley according to claim 3.

5. The rod body has a jig insertion hole into which a jig is inserted when the rod body is rotated.

4. The trolley according to claim 3.

6. The connecting rod is A lock nut for fixing the right-hand threaded shaft and the left-hand threaded shaft to the rod main body, A coupling member fixed to each of the right-hand threaded shaft and the left-hand threaded shaft; Equipped 4. The trolley according to claim 3.

7. The lock nuts are screwed onto the right-hand threaded shaft and the left-hand threaded shaft, respectively.

7. The trolley according to claim 6.

8. The joint member is formed by a joint plate that is sandwiched and fixed between the right-hand threaded shaft and the left-hand threaded shaft, The front traveling unit and the rear traveling unit have a pair of clamping plates that sandwich the joint plate, The joint plate and the clamping plate each have a connecting shaft insertion hole, When a connecting shaft is inserted into the connecting shaft insertion hole, the joint plate is rotatably connected to the clamping plate.

7. The trolley according to claim 6.

9. The front running mechanism has a front connection portion for connecting the connecting rod to one of the right side and the left side at a rear end thereof, The rear running mechanism has a rear connection portion for connecting the connecting rod to the other of the right and left sides at the front end portion. The dolly according to claim 1.

10. The platform has a front pivot shaft and a rear pivot shaft protruding from a bottom surface thereof, The front traveling unit and the rear traveling unit have a front swivel hole and a rear swivel hole into which the front swivel shaft and the rear swivel shaft are rotatably inserted, respectively. The dolly according to claim 1.

11. The front traveler has a traction member extending forward, The platform has an engagement portion with which the towing member of the following carriage is engaged. The dolly according to claim 1.

Images