JP7612306B2 - dolly - Google Patents

Description

The present invention relates to a dolly that detachably connects a towing vehicle and a towed vehicle.

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), such dolly D comprises an arm A that is connected to the towing vehicle T1, and a body B equipped with a coupler C that is connected to the 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 that extends 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 comprises a coupler mount CM that is 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 that extends 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.

JP 2000-335440 A JP 2002-200989 A

In the dollies disclosed in Patent Documents 1 and 2, the main body B can bend relative to the arm A via the first support shaft S1, the coupler base CB can swing relative to the coupler mount CM via the second support shaft 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 Br of the upper surface of the main body B will interfere with the underside of the towed vehicle T2.

To eliminate the above concerns, it is conceivable to (a) fix the main body B to the arm A while leaving 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 leaving the main body B bendable relative to the arm A. In the case of (b) above, it is further conceivable to (b-1) integrate the coupler mount CM and the coupler base CB into a single 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, leave 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 around the second support shaft S2, as shown in Figure 9-2 (c), behind the second support shaft S2 on the top surface of the main body B.

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 by it may sway up and down and left and right due to external forces from unevenness of the road surface, wind, etc. while traveling. When the upper surface of the main body B of the dolly D rotates (swings) about the second support shaft S2 with respect 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 causes driving to be hindered. On the other hand, if the vehicle sways left and right, the rear edge Er of the sway limiting device E may come into line or point contact (uneven impact) with the underside of the towed vehicle T2, and may bite into it. If this occurs, an unbalanced load is applied to the underside of the towed vehicle T2, further promoting the above-mentioned sway. In other words, the external forces received by the dolly D or towed vehicle T2 while traveling may cause the rear edge Er of the sway limiting device E to come into line or point contact with the underside of the towed vehicle, which may degrade the driving performance of the vehicle.

The present invention was made in light of the above facts, and its main technical objective 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 or the structure of the coupler itself, and without impairing the driving performance of the vehicle.

After extensive research, the inventors have discovered that the above-mentioned main technical objective can be achieved by providing a swing limiting device that supports the underside of the towed vehicle and limits the swinging of the main body around the second support axle behind or in front of, or both behind and in front of, the second support axle on the top surface of the main body, and by having the underside of the towed vehicle follow the top surface of the base portion that supports the underside of the towed vehicle in the swing limiting device.

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 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 ,
Furthermore, there is provided a dolly characterized in that 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 arranged 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 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 .

Preferably , the third support shaft extends in the vehicle width direction . The common through hole is preferably in the shape of a truncated cone with an inner diameter gradually decreasing 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 with an inner diameter gradually increasing toward the outside of the sway limiting device along the third support shaft, and the rubber bush is preferably in the shape of a truncated cone. 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.

In the dolly of the present invention, a sway limiting device is provided behind or in front of the second support shaft on the upper surface of the main body, or both behind and in front of the second support shaft, which supports the underside of the towed vehicle and limits the swinging of the main body around the second support shaft. This makes it 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 while 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.

FIG. 2 is a side view of a dolly constructed in accordance with the present invention. FIG. 2 is a plan view of the dolly shown in FIG. 1 . FIG. 2 is a front view of a swing limiting device provided on the dolly shown in FIG. 1 . FIG. 4 is a side view of the swing limiting device shown in FIG. 3 . FIG. 4 is an exploded perspective view showing components of the swing limiting device shown in FIG. 3 . 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. 1 . FIG. 7 is an enlarged view of the vicinity of the coupler in FIG. 6 . 7 is an enlarged view of the vicinity of the coupler when the upper surface of the dolly body frame in FIG. 6 rotates about a second support shaft relative to the lower surface of the towed vehicle. FIG. FIG. 1 is a diagram for explaining problems that arise when a towing vehicle and a towed vehicle are connected using a conventional dolly. FIG. 1 is a diagram for explaining problems that arise when a towing vehicle and a towed vehicle are connected using a conventional dolly.

The following provides a more detailed explanation of a preferred embodiment of a dolly constructed according to the present invention, with reference to the attached drawings. In the following explanation, all directions, front-rear, left-right, and up-down, are based on the vehicle's 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 refers to the width in the left-right direction, and therefore the vehicle width direction is synonymous with the left-right direction.

Referring to Figures 1 and 2, the 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 be an appropriate 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 of 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 the towing vehicle, which will be described later, by inserting an appropriate pin (not shown) through the lunette eye 8.

The main body 6 is provided with 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, and the main body 6 can be bent with respect to the arm 4. The main body 6 further has a single axle 14 extending in the vehicle width direction at approximately the center of the main body frame 10 in the front-rear direction. 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 Figures 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 the kingpin of the towed vehicle is provided on the upper surface of the main body frame 10. The coupler 20 comprises 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 the coupler shown in 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 is omitted. A pillow 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 pillow 27 is a rod-shaped body 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.

In a 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, to support the underside of the towed vehicle and limit the swing of the main body 6 around the second support shaft 26. The swing limiting device 28 will be described mainly with reference to Figures 3 to 5. The swing limiting device 28 comprises 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 horizontally, and the base section 32 can swing (pitch) around 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).

The mount section 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 is 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 whose inner diameter gradually increases toward the outside of the swing limiting device 28 along the third support axis 36 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. In the illustrated embodiment, the guide tube wall 44 is truncated cone shape. Between the guide tube wall 44 and the mount bottom wall 38, a rib 46 is provided that extends 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.

The base portion 32 is a square tube shape that penetrates vertically to the third support shaft 36, and is equipped with 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 long 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 arranged on its upper surface. The plate material 52 is preferably an engineering plastic that has high hardness, good slipperiness, and excellent load resistance and wear resistance. The plate material 52 is fixed to the upper surface of the base top wall 48 by an appropriate 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 are both isosceles trapezoids with an upper side longer than a lower side, and are parallel to each other with a gap on the third support axis 36. Each of the pair of base side walls 50 has a base through hole 54 formed on the third support axis 36. Like the mount through hole 42, the base through hole 54 is also a truncated cone shape whose inner diameter gradually decreases toward the inside of the swing limiting device 28 along the third support axis 36.

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 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 common through holes 56 are formed on both axial sides of the third support shaft 36, and since the mount through holes 42 and the base through holes 54 are both truncated cones whose inner diameters gradually decrease toward the inside of the swing limiting device 28 along the third support shaft 36, the common through hole 56 also has a truncated cone shape whose inner diameter gradually decreases 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 the rubber bushings 58 are fitted into each of the two common through holes 56. The rubber bushings 58 have an axial hole 60 that extends linearly in the axial direction and penetrates the rubber bushings 58, and a shaft member 62 with a circular cross section that extends linearly along the third support shaft 36 is commonly inserted into each of the axial holes 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 penetrates 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.

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 is frustoconical 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.

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 shaft on the upper surface of the main body 6, and the third support shaft 36 provided on both sway limiting devices 28 both extend in the vehicle width direction.

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 axle 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 with only its own axle WS, and the front end drops and touches the ground. For this reason, the towed vehicle T2 is provided with auxiliary legs F which are extendable in the vertical direction, located forward of the axle WS and somewhat rearward of the kingpin, and when not connected to the dolly 2, the auxiliary legs F are extended to support the towed vehicle T2. 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 52 is disposed 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 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 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 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. FIG. 7 is an enlarged view of the vicinity of the coupler 20 of the dolly 2 in FIG. 6. 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. 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.

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 clockwise rotation (swing) of the coupler base 24 relative to the coupler mount 22 in FIG. 7 around the second support shaft 26. Therefore, in the dolly of the present invention, the swing of the main body 6 around 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 counterclockwise rotation (swing) of the coupler base relative to the coupler mount in FIG. 7 around the second support shaft 26 is limited by the pillow 27.

Meanwhile, the dolly 2 and the towing vehicle T1 and towed vehicle T2 connected by it may sway up and down and left and right while traveling due to external forces such as unevenness of the road surface and wind. When the top surface of the main frame 10 of the dolly 2 rotates (sways) counterclockwise in FIG. 7 about the second support shaft 26 relative to the bottom surface of the towed vehicle T2 due to the vertical sway, the distance between the top surface of the main frame 10 and the bottom surface of the towed vehicle T2 gradually decreases behind the second support shaft 26, so that the rear edge of the sway limiting device 28, i.e., the rear edge of the top surface of the plate material 52, comes into line contact with the bottom surface of the towed vehicle T2 and is likely to get caught in it. However, because the base portion 32 can swing around the third support shaft 36 relative to the mount portion 30, as shown in FIG. 8, the base portion 32 swings (pitches) around the third support shaft 36 relative to the mount portion 30, and the upper surface of the plate material 52 can maintain surface contact with the underside of the towed vehicle T2, which prevents 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) around the third support shaft 36 relative to the mount portion 30, but also roll and yaw, so the upper surface of the base portion 32 can follow the underside of the towed vehicle T2 and maintain surface contact, which prevents 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.

In other words, in the dolly 2 of the present invention, the upper surface of the base part 32 that supports 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 driving, 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 hitting the underside of the towed vehicle T2 unevenly, 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 part 32 of the sway limiting device 28 equipped 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 is in sufficiently reliable 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 mount portion 30 and the base portion 32 of the sway limiting device 28, absorbing the impact between the mount portion 30 and the base portion 32, allowing the base portion 32 to easily follow the underside of the towed vehicle T2.

The dolly constructed according to the present invention has been described above in detail with reference to the attached 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 arranged only rearward of the second support shaft 26 on the upper surface of the main body 6, but the same swing limiting device 28 may be arranged in place of the pillow 27, that is, in front of the second support shaft 26. By arranging the swing limiting device 28 both in front and behind 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 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 balanced manner, the number and position 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. In addition, the connecting means connecting the base portion and the mount portion of the sway limiting device does not necessarily have to be an axis, and the two parts can be connected with a relatively flexible material such as rubber.

2: Dolly 4: Arm 6: Main body 12: First support shaft 14: Axle 20: Coupler 22: Coupler mount 24: Coupler base 26: Second support shaft 28: Swing limiting device 30: Mount portion 32: Base portion 36: Third support shaft (connection means)
52: Plate material 58: Rubber bush T1: Towing vehicle T2: Towed vehicle

Claims (6)

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

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