dolly

Abstract

To provide a new dolly that prevents a main body from oscillating about a second support shaft as an axis without changing a frame structure of the main body and a structure of a coupler and deteriorating operability of a vehicle.SOLUTION: An oscillation restriction device 28 supporting a lower surface of a towed car T2 to restrict a main body 6 from oscillating about a second support shaft 26 is disposed rearward or forward of the second support shaft 26 on an upper surface of the main body 6 or the swing restriction devices are disposed rearward and forward of the second support shaft. The lower surface of the towed vehicle T2 is followed by an upper surface of a base portion 32 of the oscillation restriction device 28 supporting the lower surface of the towed vehicle T2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a dolly for detachably connecting a towing vehicle and a towed vehicle. [Background technology]

[0002] For example, the following Patent Documents 1 and 2 disclose a dolly D that detachably connects a towing vehicle T1 such as a full tractor and a towed vehicle T2 such as a semi-trailer. Explaining with reference to FIG. 9-1(a), the dolly D includes an arm A connected to the towing vehicle T1 and a body B equipped with a coupler C connected to a kingpin of the towed vehicle T2, and the front end of the body B is connected to the rear end of the arm A via a first support shaft S1 extending in the vehicle width direction, so that the body B can bend with respect to the arm A. The body B has a single axle WS. The coupler C includes a coupler mount CM fixed to the upper surface of the body B and a coupler base CB that supports the lower surface of the towed vehicle T2, and the coupler base CB is connected to the coupler mount CM via a second support shaft S2 extending in the vehicle width direction, so that the coupler base CB can swing around the second support shaft S2 relative to the coupler mount CM. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-335440 A [Patent Document 2] JP 2002-200989 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the dollies disclosed in Patent Documents 1 and 2 above, the main body B can be bent relative to the arm A by the first support axis S1, the coupler base CB can swing relative to the coupler mount CM by the second support axis S2, and the main body B has a single axle WS.As a result, when the towing vehicle T1 tows the towed vehicle T2 via the dolly D, as shown in Figure 9-1(b), the upper surface of the main body B is excessively inclined relative to the underside of the towed vehicle T2, and there is a risk that the rear end portion Br of the upper surface of the main body B will interfere with the underside of the towed vehicle T2.

[0005] In order to eliminate the above-mentioned concerns, it is conceivable to (a) fix the main body B to the arm A while keeping the coupler base CB swingable relative to the coupler mount CM, or (b) suppress or limit the swinging of the coupler base CB relative to the coupler mount CM while keeping the main body B bendable relative to the arm A. In the above (b), it is further conceivable to (b-1) integrate the coupler mount CM and the coupler base CB into an integral structure to completely suppress the swinging of the coupler base CB relative to the coupler mount CM, or (b-2) leave the structure of the coupler C as it is, that is, keep the coupler base CB swingable relative to the coupler mount CM, and provide a swing limiting device E such as a fixed pillow to limit the swinging of the main body B about the second support shaft S2, as shown in Fig. 9-2(c), behind the second support shaft S2 on the upper surface of the main body B.

[0006] However, in the above (a), it is necessary to enlarge the frame of the main body B from the viewpoint of ensuring the strength of the entire dolly D, which is not preferable. In the above (b-1), the structure of the coupler C itself is changed, which is not preferable from the viewpoint of quality assurance of the coupler C. In the above (b-2), it is not preferable for the following reasons. The dolly D and the towing vehicle T1 and towed vehicle T2 connected thereto may sway up and down and left and right due to external forces from unevenness of the road surface, wind, etc. during driving. When the upper surface of the main body B of the dolly D rotates (swings) about the second support shaft S2 relative to the lower surface of the towed vehicle T2 due to the vertical sway, and as shown in Figure 9-2 (d), when the rear end edge Er of the sway limiting device E abuts against the lower surface of the towed vehicle T2, such abutment becomes a line contact (uneven contact), and the rear end edge Er of the sway limiting device E may bite into the lower surface of the towed vehicle T2, which may cause driving to be hindered. On the other hand, if the vehicle sways left and right, the rear end edge Er of the sway limiting device E may come into line or point contact (uneven contact) with the underside of the towed vehicle T2 and bite into it, and if this occurs, an unbalanced load is applied to the underside of the towed vehicle T2, which further exacerbates the sway. In other words, there is a risk that the driving performance of the vehicle will deteriorate if the rear end edge Er of the sway limiting device E comes into line or point contact with the underside of the towed vehicle due to external forces received by the dolly D or the towed vehicle T2 while traveling.

[0007] The present invention has been made in consideration of the above-mentioned facts, and its main technical object is to provide a new and improved dolly in which the main body is prevented from swinging about the second support shaft without changing the frame structure of the main body and the structure of the coupler itself, and without impairing the driving performance of the vehicle. [Means for solving the problem]

[0008] After careful consideration, the inventors have discovered that the above-mentioned main technical objective can be achieved by providing a sway limiting device behind or in front of, or both behind and in front of, the second support axle on the upper surface of the main body, which supports the underside of the towed vehicle and limits the main body from swinging around the second support axle, and by having the underside of the towed vehicle follow the upper surface of a base portion that supports the underside of the towed vehicle in the sway limiting device.

[0009] That is, according to the present invention, as a dolly that achieves the above-mentioned main technical object, a dolly for detachably connecting a towing vehicle and a towed vehicle is provided, a main body including an arm connected to a towing vehicle and a coupler connected to a kingpin of a towed vehicle, a front end of the main body being connected to a rear end of the arm via a first support shaft extending in a vehicle width direction, and the main body being bendable relative to the arm, The body has a single axle; In a dolly, the coupler includes a coupler mount fixed to an upper surface of the main body and a coupler base supporting an underside of a towed vehicle, the coupler base being connected to the coupler mount via a second support shaft extending in a vehicle width direction, and the coupler base being swingable about the second support shaft relative to the coupler mount, a swing limiting device is provided on the upper surface of the main body behind or in front of the second support shaft, or both behind and in front of the second support shaft, for supporting the underside of the towed vehicle and limiting the swing of the main body around the second support shaft; The sway limiting device includes a mount portion fixed to the upper surface of the main body and a base portion supporting the lower surface of the towed vehicle, A third support shaft extending horizontally is connected to the mount portion via the base portion is pivotable about the third support shaft relative to the mount portion, The upper surface of the base portion follows the lower surface of the towed vehicle. death, Furthermore, the mount portion has a pair of mount side walls perpendicular to the upper surface of the main body, and the base portion has a pair of base side walls hanging downward from a base upper wall supporting the underside of the towed vehicle, the pair of mount side walls and the pair of base side walls are each disposed perpendicular to the third support shaft, the inner surface of each of the pair of mount side walls faces the outer surface of each of the pair of base side walls, a common through hole is formed on the third support shaft in each of the pair of mount side walls and the pair of base side walls, and a rubber bush is fitted into the common through hole. A dolly is provided, comprising:

[0010] Preferably ,before The third support shaft extends in the vehicle width direction. BeforeThe common through hole is preferably a truncated cone shape whose inner diameter gradually decreases toward the inside of the sway limiting device along the third support shaft. A guide tube wall is provided on the outer surface of each of the pair of mount side walls, surrounding the outer periphery of the common through hole and whose inner diameter gradually increases toward the outside of the sway limiting device along the third support shaft, and the rubber bush is preferably a truncated cone shape. Preferably, a synthetic resin plate is disposed on the upper surface of the base portion, and the base portion supports the underside of the towed vehicle via the plate. In this case, when the upper surface of the coupler base does not support the underside of the towed vehicle and is in a horizontal state, the upper surface of the plate is preferably located at the same height as or higher than the upper surface of the coupler base. Effect of the Invention

[0011] In the dolly of the present invention, a sway limiting device is provided on the upper surface of the main body behind or in front of the second support shaft, or both behind and in front of the second support shaft, for supporting the underside of the towed vehicle and limiting the swinging of the main body around the second support shaft, so that it is possible to limit the swinging of the main body around the second support shaft without changing the frame structure of the main body or the structure of the coupler itself.Furthermore, in the dolly of the present invention, the upper surface of the base part that supports the underside of the towed vehicle in the sway limiting device follows the underside of the towed vehicle, so that even if an external force is applied during traveling, the upper surface of the sway limiting device is prevented from hitting the underside of the towed vehicle unevenly, and as a result, the driving performance of the vehicle is not impaired. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a side view of a dolly constructed in accordance with the present invention. [Diagram 2] FIG. 2 is a plan view of the dolly shown in FIG. 1. [Diagram 3] FIG. 2 is a front view of a swing limiting device provided on the dolly shown in FIG. 1. [Figure 4] FIG. 4 is a side view of the swing limiting device shown in FIG. 3. [Diagram 5] FIG. 4 is an exploded perspective view showing components of the swing limiting device shown in FIG. 3. [Figure 6] FIG. 2 is a side view showing a state in which a towing vehicle and a towed vehicle are coupled together using the dolly shown in FIG. [Figure 7] FIG. 7 is an enlarged view of the vicinity of the coupler in FIG. 6. [Figure 8] 7 is an enlarged view of the vicinity of the coupler in FIG. 6 when the upper surface of the dolly body frame rotates about a second support shaft relative to the lower surface of the towed vehicle. FIG. [Figure 9-1] FIG. 1 is a diagram for explaining problems that arise when a towing vehicle and a towed vehicle are connected using a conventional dolly. [Figure 9-2] FIG. 1 is a diagram for explaining problems that arise when a towing vehicle and a towed vehicle are connected using a conventional dolly. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A more detailed description will be given below with reference to the attached drawings showing preferred embodiments of a dolly constructed according to the present invention. In the following description, the front-rear, left-right, and up-down directions are all based on the vehicle travel direction, unless otherwise specified, and the left side of the paper in Figures 1, 2, and 6 is the front. Furthermore, the vehicle width means the width in the left-right direction, and therefore the vehicle width direction is synonymous with the left-right direction.

[0014] Explaining with reference to Figures 1 and 2, a dolly generally designated by the numeral 2 includes an arm 4 and a main body 6. In the illustrated embodiment, the arm 4 is a so-called A-arm, and is generally A-shaped in plan view. If desired, the arm may have any other suitable shape, such as an I-shape extending linearly in the fore-aft direction. The front top of the arm 4 is located in the center in the vehicle width direction, and a well-known lunette eye 8 is provided at this position. The arm 4 is connected to the rear end of a towing vehicle (described later) by inserting an appropriate pin (not shown) through the lunette eye 8.

[0015] The main body 6 includes a main body frame 10 having a rectangular shape in a plan view. The length of the main body frame 10 in the vehicle width direction is approximately the same as the length of the rear end of the arm 4 in the vehicle width direction, and the front end of the main body frame 10 is connected to the rear end of the arm 4 via a first support shaft 12 extending in the vehicle width direction, so that the main body 6 can bend with respect to the arm 4. The main body 6 further includes a single axle 14 extending in the vehicle width direction at approximately the center in the front-rear direction of the main body frame 10. On the axle 14, tires 16 are arranged, one on each side of the main body frame 10. The upper surface of each tire 16 is covered by a cowl 18. In Figs. 1 and 2, the tires 16 and the cowl 18 are indicated by two-dot chain lines. The cowl 18 is supported and fixed to the main body frame 10 by a connecting piece 19. A coupler 20 that is connected to a kingpin of a towed vehicle is provided on the upper surface of the main body frame 10. The coupler 20 includes a coupler mount 22 fixed to the main frame 10 and a coupler base 24 that supports the underside of the towed vehicle, and the coupler base 24 is swingably connected to the coupler mount 22 via a second support shaft 26 extending in the vehicle width direction. As can be understood by referring to FIG. 2, the second support shaft 26 is located slightly rearward of the axle 14. Such a coupler 20 may be a conventionally known coupler (such as a coupler shown in Japanese Patent No. 4146931) that is used when a towing vehicle such as a semi-tractor tows a towed vehicle such as a semi-trailer without using a dolly, and therefore a detailed description of the coupler 20 will be omitted. A bolster 27 extending in the vehicle width direction is fixed to the top surface of the main frame 10 forward of the second support shaft 26. The bolster 27 is rod-shaped with a rectangular cross section, and a synthetic resin plate material 27a is fixed to the top surface of both ends in the vehicle width direction by an appropriate fastener such as a bolt.

[0016] In the dolly constructed according to the present invention, it is important that a swing limiting device 28 is provided on the upper surface of the main body 6, behind or in front of the second support shaft 26, or both behind and in front of the second support shaft 26, for supporting the underside of the towed vehicle and limiting the swing of the main body 6 about the second support shaft 26. The swing limiting device 28 will be described mainly with reference to Figs. 3 to 5. The swing limiting device 28 includes a mount section 30 fixed to the upper surface of the main body 6 and a base section 32 supporting the underside of the towed vehicle, and the base section 32 is connected to the mount section 30 via a connecting means. In the illustrated embodiment, the connecting means is a third support shaft 36 extending in the horizontal direction, and the base section 32 is capable of swinging (pitching) about the third support shaft 36 relative to the mount section 30 (as will be described later, in the illustrated embodiment, the third support shaft 36 extends in the vehicle width direction).

[0017] The mount portion 30 includes a mount bottom wall 38 fixed to the upper surface of the main body 6 by an appropriate fixing means, and a pair of mount side walls 40 extending vertically upward from the upper surface of the mount bottom wall 38 (and therefore perpendicular to the upper surface of the main body 6). Each of the pair of mount side walls 40 is perpendicular to the third support axis 36 and is parallel to each other at a distance on the third support axis 36. A mount through hole 42 is formed on each of the pair of mount side walls 40 on the third support axis 36. The mount through hole 42 has a truncated cone shape whose inner diameter gradually decreases toward the inside of the swing limiting device 28 along the third support axis 36. A guide tube wall 44 is provided on the outer surface of each of the pair of mount side walls 40, surrounding the outer periphery of the mount through hole 42 and whose inner diameter gradually increases toward the outside of the swing limiting device 28 along the third support axis 36. In the illustrated embodiment, the guide tube wall 44 has a truncated cone shape. A rib 46 is provided between the guide cylinder wall 44 and the mount bottom wall 38, extending from the outer surface of the mount side wall 40 along the third support axis 36 toward the outside of the swing limiting device 28.

[0018] The base portion 32 is a square tube shape that penetrates vertically to the third support shaft 36, and includes a base top wall 48 that supports the underside of the towed vehicle, and a pair of base side walls 50 that hang down from both side edges of the base top wall 48. The base top wall 48 is a rectangular shape that is elongated vertically to the third support shaft 36, and a synthetic resin plate material 52 of substantially the same shape as the base top wall 48 is disposed on its upper surface. The plate material 52 is preferably an engineering plastic that has high hardness, good sliding properties, and excellent load resistance and abrasion resistance. The plate material 52 is fixed to the upper surface of the base top wall 48 by a suitable fastener such as a bolt. Here, when the upper surface of the coupler base 24 does not support the underside of the towed vehicle and is in a horizontal state, the upper surface of the plate material 52 is preferably located at the same height as or higher than the upper surface of the coupler base 24. The reason for this will be described later. The pair of base side walls 50 each have an isosceles trapezoidal shape with an upper side longer than a lower side, and are parallel to each other at a distance on the third support axis 36. A base through hole 54 is formed in each of the pair of base side walls 50 on the third support axis 36. Like the mount through hole 42, the base through hole 54 also has a truncated cone shape with an inner diameter that gradually decreases toward the inside of the swing limiting device 28 along the third support axis 36.

[0019] The mount section 30 and the base section 32 are assembled by facing the inner surfaces of the pair of mount side walls 40 to the outer surfaces of the pair of base side walls 50, aligning the mount through holes 42 and the base through holes 54 to form a common through hole 56 on the third support shaft 36, and fitting a rubber bush 58 into the common through hole 56. It is preferable that a small gap exists between the inner surface of the mount side wall 40 and the outer surface of the base side wall 50. The common through holes 56 are formed on both sides of the third support shaft 36 in the axial direction, and since the mount through holes 42 and the base through holes 54 are both frustum conical in shape with the inner diameter gradually decreasing toward the inside of the swing limiting device 28 along the third support shaft 36, the common through hole 56 also has a frustum conical shape with the inner diameter gradually decreasing toward the inside of the swing limiting device 28 along the third support shaft 36. The rubber bushing 58 has a truncated cone shape corresponding to the common through hole 56, and is fitted from the outer surface side of the mount side wall 40. In other words, there are two rubber bushings 58, and each rubber bushing 58 is fitted into each of the two common through holes 56. A shaft hole 60 is formed in the rubber bushing 58, which extends linearly in the axial direction, and a shaft member 62 having a circular cross section and extending linearly along the third support shaft 36 is commonly inserted into each shaft hole 60 of the two rubber bushings 58. A flange 64 is fixed to one end of the shaft member 62, and the flange 64 supports the outer end surface of one of the rubber bushings 58. The other end of the shaft member 62 completely passes through the other rubber bushing 58, and a fastener 68 such as a nut is fastened to the other end of the shaft member 62 via a disk 66 (therefore, at least the other end of the shaft member 62 has a male thread formed thereon), and the disk 66 supports the outer end surface of the other rubber bushing 58.

[0020] In the illustrated embodiment, the rubber bush 58 is fitted into the common through hole 56, i.e., the mount section 30 and the base section 32 are connected by the rubber bush 58, which is a rubber bush having elasticity, so that the base section 32 can move somewhat in the direction perpendicular to the third support shaft 36 relative to the mount section 30. Furthermore, because the rubber bush 58 has a truncated cone shape and there is a small gap between the inner surface of the mount side wall 40 and the outer surface of the base side wall 50, the base section 32 can roll and yaw somewhat about the third support shaft 36 relative to the mount section 30. In other words, the base section 32 can not only oscillate (pitch) about the third support shaft 36 relative to the mount section 30, but also roll and yaw slightly.

[0021] As can be understood by referring to Figures 1 and 2, in the illustrated embodiment, one sway limiting device 28 is provided on each side end of the main body frame 10 in the vehicle width direction, rearward of the second support axis on the upper surface of the main body 6, and the third support axis 36 provided on the two sway limiting devices 28 both extend in the vehicle width direction.

[0022] In FIG. 6, the towing vehicle T1 and the towed vehicle T2 connected by the dolly 2 are also shown by two-dot chain lines. In the illustrated embodiment, the towing vehicle T1 is a full tractor, and the lunette eye 8 of the dolly 2 is connected to the rear end of the towing vehicle T1. On the other hand, the towed vehicle T2 is a semi-trailer, and the coupler 20 of the dolly 2 is connected to the kingpin (not shown) of the towed vehicle T2. As can be understood by referring to FIG. 6, the towed vehicle T2 has two axles WS, but both axles WS are located at the rear end of the vehicle, and there is no axle at the front end, and the front end of the towed vehicle T2 is supported by the axles 14 of the dolly 2. Therefore, when the towed vehicle T2 is not connected to the dolly 2 and is alone, it cannot maintain the posture shown in FIG. 6 using only its own axles WS, and the front end drops and touches the ground. For this reason, the towed vehicle T2 is provided with auxiliary legs F that are vertically extendable and contractible at a position forward of the axle WS and somewhat rearward of the kingpin, and supports itself by extending the auxiliary legs F when not connected to the dolly 2. When connecting the towed vehicle T2 to the dolly 2, after the dolly 2 is placed in the required position, the auxiliary legs F are contracted to lower the front end of the towed vehicle T2 and support it on the upper surface of the coupler 20 of the dolly 2. As described above, in the illustrated embodiment, a synthetic resin plate material 52 is arranged on the upper surface of the base portion 32 of the sway limiting device 28 equipped on the dolly 2, and when the upper surface of the coupler base 24 does not support the underside of the towed vehicle T2 and is in a horizontal state, the upper surface of the plate material 52 is located at the same height as or higher than the upper surface of the coupler base 24. Therefore, when the towed vehicle T2 is coupled to the dolly 2, the plate material 52 of the sway limiting device 28 abuts against the underside of the towed vehicle T2 before the upper surface of the coupler 20 of the dolly 2, i.e., the upper surface of the coupler base 24, abuts against the underside of the towed vehicle T2, and as the front end of the towed vehicle T2 descends, the rubber bushing 58 is compressed, and the upper surface of the plate material 52 is in surface contact with the underside of the towed vehicle T2 and the upper surface of the coupler base 24 supports the underside of the towed vehicle T2.Figure 7 is an enlarged view of the vicinity of the coupler 20 of the dolly 2 in Figure 6, and as can be understood by referring to this figure, the upper surface of the coupler base 24 of the coupler 20 and the upper surface of the base portion 32 of the sway limiting device 28 both support the underside of the towed vehicle T2, and in the illustrated embodiment, the base portion 32 of the sway limiting device 28 supports the underside of the towed vehicle T2 via a plate material 52.

[0023] In the state shown in Fig. 7, the upper surface of the main body frame 10 of the dolly 2 is substantially horizontal, which is substantially parallel to the lower surface of the towed vehicle T2, and the upper surface of the coupler base 24 and the upper surface of the plate material 52 provided on the base portion 32 of the swing limiting device 28 are both in surface contact with the lower surface of the towed vehicle T2. For this reason, the presence of the swing limiting device 28 limits the coupler base 24 from rotating (swinging) in the clockwise direction in Fig. 7 about the second support shaft 26 relative to the coupler mount 22. Therefore, in the dolly of the present invention, the swing of the main body 6 about the second support shaft 26 can be limited without changing the frame structure of the main body 6 and the structure of the coupler 20 itself, and this prevents the upper surface of the main body 6 from excessively inclining with respect to the lower surface of the towed vehicle T2 and interfering with it. The bolster 27 limits the coupler base from rotating (swinging) in the counterclockwise direction in Fig. 7 about the second support shaft 26 relative to the coupler mount.

[0024] Meanwhile, the dolly 2 and the towing vehicle T1 and towed vehicle T2 connected thereby may sway up and down and left and right while traveling due to external forces from unevenness of the road surface, wind, etc. When the upper surface of the main frame 10 of the dolly 2 rotates (sways) counterclockwise in Fig. 7 with respect to the underside of the towed vehicle T2 about the second support shaft 26 due to the vertical sway, the distance between the upper surface of the main frame 10 and the underside of the towed vehicle T2 gradually decreases behind the second support shaft 26, so that the rear end edge of the sway limiting device 28, i.e., the rear end edge of the upper surface of the plate material 52, comes into line contact with the underside of the towed vehicle T2 and is likely to get caught therein. However, because the base portion 32 can swing relative to the mount portion 30 around the third support shaft 36, as shown in Fig. 8, the base portion 32 swings (pitches) relative to the mount portion 30 around the third support shaft 36, and the upper surface of the plate material 52 can maintain surface contact with the underside of the towed vehicle T2, thereby preventing the upper surface of the plate material 52 from making line contact with the underside of the towed vehicle T2 and biting into it. On the other hand, as described above, in terms of lateral wobble, the base portion 32 can not only swing (pitch) relative to the mount portion 30 around the third support shaft 36, but also roll and yaw, so that the upper surface of the base portion 32 can follow the underside of the towed vehicle T2 and maintain surface contact, thereby preventing the upper surface of the plate material 52 from making line or surface contact with the underside of the towed vehicle T2 and biting into it.

[0025] That is, in the dolly 2 of the present invention, the upper surface of the base portion 32 supporting the underside of the towed vehicle T2 in the sway limiting device 28 follows the underside of the towed vehicle T2, so that even if an external force is applied during traveling, the upper surface of the sway limiting device 28, i.e., the upper surface of the plate material 52 arranged on the base upper wall 48, is prevented from unevenly contacting the underside of the towed vehicle T2, and thus the driving performance of the vehicle is not impaired. In the illustrated embodiment, a synthetic resin plate material 52 is further arranged on the upper surface of the base portion 32 of the sway limiting device 28 provided in the dolly 2, and when the upper surface of the coupler base 24 does not support the underside of the towed vehicle T2 and is in a horizontal state, the upper surface of the plate material 52 is located at the same height as or higher than the upper surface of the coupler base 24, so that as described above, when the dolly 2 and the towed vehicle T2 are connected, the plate material 52 is compressed and elastically deformed, so that the upper surface of the plate material 52 comes into sufficiently and reliably surface contact with the underside of the towed vehicle T2. Furthermore, a rubber bushing 58 is fitted into the common through hole 56 of the mounting portion 30 and the base portion 32 in the sway limiting device 28, thereby absorbing the impact between the mounting portion 30 and the base portion 32, allowing the base portion 32 to easily follow the underside of the towed vehicle T2.

[0026] The dolly constructed according to the present invention has been described above in detail with reference to the accompanying drawings, but the present invention is not limited to the above-mentioned embodiment, and appropriate modifications and changes are possible within the scope of the present invention. For example, in the illustrated embodiment, the swing limiting device 28 is disposed only behind the second support shaft 26 on the upper surface of the main body 6, but the same swing limiting device 28 may be disposed in place of the pillow 27, that is, disposed forward of the second support shaft 26. By disposing the swing limiting device 28 both forward and rearward of the second support shaft 26, even if the upper surface of the main body frame 10 of the dolly 2 rotates (swings) clockwise in FIG. 7 about the second support shaft 26 relative to the lower surface of the towed vehicle T2 due to vertical wobble, the swing of the coupler base 24 relative to the coupler mount 22 can be limited and the above-mentioned biting and galling can be prevented. In the illustrated embodiment, the sway limiting device 28 is provided on each side end of the main frame 10 in the vehicle width direction, but as long as the upper surface of the base portion 32 and the upper surface of the coupler base 24 can support the lower surface of the towed vehicle T2 in a well-balanced manner, the number and positions of the sway limiting devices 28 may be arbitrary. For example, a single sway limiting device 28 may be disposed in the center of the vehicle width direction behind or in front of the second support shaft 26. Furthermore, as described above, the sway limiting device 28 can not only pitch but also roll and yaw with respect to the third support shaft 36, so the third support shaft 36 does not necessarily have to be the same as the vehicle width direction. Also, the connecting means for connecting the base portion and the mount portion of the sway limiting device does not necessarily have to be an axis, and the two portions can be connected with a relatively flexible material such as rubber. [Explanation of symbols]

[0027] 2: Dolly 4: Arm 6: Main unit 12: First support axis 14: Axle 20: Coupler 22: Coupler mount 24: Coupler Base 26: Second support axis 28: Swing limiting device 30: Mounting section 32: Base section 36: Third support shaft (connection means) 52: Board material 58: Rubber bush T1: Towing vehicle T2: Towed vehicle

Claims

1. A dolly is provided for detachably connecting a towing vehicle and a towed vehicle, a main body including an arm connected to a towing vehicle and a coupler connected to a kingpin of a towed vehicle, a front end of the main body being connected to a rear end of the arm via a first support shaft extending in a vehicle width direction, and the main body being bendable relative to the arm, The body has a single axle; In a dolly, the coupler includes a coupler mount fixed to an upper surface of the main body and a coupler base supporting an underside of a towed vehicle, the coupler base being connected to the coupler mount via a second support shaft extending in a vehicle width direction, and the coupler base being swingable about the second support shaft relative to the coupler mount, a swing limiting device is provided on the upper surface of the main body behind or in front of the second support shaft, or both behind and in front of the second support shaft, for supporting the underside of the towed vehicle and limiting the swing of the main body around the second support shaft; The sway limiting device includes a mount portion fixed to an upper surface of the main body and a base portion supporting an underside of the towed vehicle, the base portion being connected to the mount portion via a third support shaft extending horizontally, the base portion being capable of swinging relative to the mount portion about the third support shaft, and the upper surface of the base portion following the underside of the towed vehicle, The dolly further comprises a pair of mount side walls perpendicular to the upper surface of the main body, and a pair of base side walls hanging downward from a base upper wall supporting the underside of the towed vehicle, the pair of mount side walls and the pair of base side walls are each arranged perpendicular to the third support shaft, an inner surface of each of the pair of mount side walls faces an outer surface of each of the pair of base side walls, a common through hole is formed in each of the pair of mount side walls and the pair of base side walls above the third support shaft, and a rubber bushing is fitted into the common through hole.

2. The dolly according to claim 1 , wherein the third support shaft extends in a vehicle width direction.

3. 3. The dolly according to claim 1 or 2, wherein the common through hole has a truncated cone shape with an inner diameter gradually decreasing toward the inside of the swing limiting device along the third support axis.

4. A dolly as described in any one of claims 1 to 3, wherein a guide tube wall is provided on the outer surface of each of the pair of mount side walls, surrounding the outer peripheral edge of the common through hole and having an inner diameter gradually increasing toward the outside of the swing limiting device along the third support axis, and the rubber bush is frustum shaped.

5. 5. The dolly according to claim 1, wherein a synthetic resin plate is disposed on an upper surface of said base portion, and said base portion supports an underside of a towed vehicle via said plate.

6. 6. The dolly according to claim 5, wherein when the upper surface of the coupler base does not support the underside of the towed vehicle and is in a horizontal state, the upper surface of the plate material is positioned at the same height as or higher than the upper surface of the coupler base.

Images