JP2800546B2 - Rear wheel steering device such as truck - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel steering device for a truck or the like.

[0002]

2. Description of the Related Art In recent years, various four-wheel steering systems and devices have been proposed in which the rear wheels are steered in conjunction with the steering of the front wheels in order to improve the steering stability during high-speed running. Conventionally, in a truck in which a rear wheel is supported at both ends in a vehicle width direction of a rigid axle tube or a rear axle housing, and the rear axle housing is suspended on a chassis frame through a leaf spring device, the rear axle housing itself is used. Is disclosed in Japanese Utility Model Laid-Open Publication No. 2-120284 in which the rear wheel steering device is rotated around a rotation center disposed on a center line in the vehicle longitudinal direction.

[0003] The above-mentioned proposed rear wheel steering device is a frame-shaped spring which is tightened by tie bolts to the leaf spring device in order to allow relative displacement between the rear axle housing and the leaf spring device during turning. An arcuate guide groove is provided in the seat, and an arcuately curved slider mounted on the rear axle housing is slidably fitted in the guide groove, and the rear axle housing is The rear axle housing is connected to one end of a bell crank rotatably supported by the spring seat, and the other end of the bell axle is connected to the rear axle housing in order to rotate around the center of rotation on the center line in the vehicle longitudinal direction. The piston shaft of the hydraulic cylinder device fixed to the differential case provided at the center in the vehicle width direction Linked structure is adopted.

However, in the above rear wheel steering device, the rear wheel steering actuator, that is, the hydraulic cylinder device is frequently supported during traveling, particularly in the rear axle housing which makes a shocking displacement in the vertical direction. And a frame-shaped spring seat fixed to the above-mentioned leaf spring device, and a rear axle housing side which slides inside the spring seat to perform an arc motion during steering. Is located at a low position near the ground surface, a large amount of muddy water, gravel, pebbles, etc. inevitably enter the circular sliding surface between the two, and the slider slides smoothly against the spring seat. Relative sliding is hindered, requiring a large-capacity hydraulic cylinder, hydraulic control valve, hydraulic source, and a spring seat and Wear of the arc sliding surface of the slider is significantly, there is a disadvantage that the durability and reliability may be impaired.

According to the present invention, a rear axle housing is supported at both ends in the vehicle width direction of a rear axle housing, and the rear axle housing has a simple, inexpensive and durable structure in a truck or the like mounted on a chassis frame via a leaf spring device. It is an object of the present invention to provide a rear wheel steering device excellent in reliability and reliability.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and comprises a chassis frame, a rear axle housing supporting rear wheels at both ends in a vehicle width direction,
A rear axle housing sandwiching the rear axle housing from above and below, and a rubber pad member sandwiching the rear axle housing from above and below are fastened to the rear axle housing by a tightening device such as a U bolt and shackle links are provided at both ends in the vehicle longitudinal direction. A leaf spring device pivotally attached to the chassis frame via a center line in the longitudinal direction of the vehicle body, one end of which is pivotally attached to a central portion of the rear axle housing in the vehicle width direction and the other end of which is An upper radius rod pivotally attached to the chassis frame, a pair of left and right lower radius rods disposed substantially symmetrically on both sides of the longitudinal centerline of the vehicle body and having one end pivotally attached to the rear axle housing, on the chassis frame. Left side pivotally supported and one end of each pivoted to the other end of the lower radius rod A pair of L-shaped levers, connecting rods extending in the vehicle width direction and having both ends pivotally connected to the other ends of the left and right L-shaped levers, respectively, and supported by the chassis frame; The left and right lower radius rods are connected to one of the L-shaped levers and rotate the other L-shaped lever through the L-shaped lever and the connecting rod in response to steering and steering of the vehicle during high-speed running. A single rear wheel steering actuator for driving the rear axle housing around the other end pivot point of the upper radius rod by driving the rear axle housing in opposite directions. Device and the rear wheel steering actuator are connected to the one L
A rear wheel steering device is proposed in which the L-shaped lever is connected to the L-shaped lever at a portion farther from the pivot point of the connecting rod with respect to the pivot axis of the L-shaped lever with respect to the chassis frame.

Further, the present invention provides a rear axle housing by a tightening device such as a U bolt via a chassis frame, a rear axle housing supporting rear wheels at both ends in a vehicle width direction, and a rubber pad member sandwiching the rear axle housing from above and below. The leaf spring device is attached to the chassis frame via shackle links at both ends in the vehicle longitudinal direction, and is disposed along the vehicle longitudinal direction center line and has one end thereof mounted on the rear axle housing. An upper radius rod pivotally connected to the center portion in the width direction and the other end pivotally connected to the chassis frame, respectively, is disposed substantially symmetrically on both sides of a longitudinal centerline of the vehicle body, and has one end connected to the rear axle housing. A pair of left and right lower radius rods pivotally mounted on the chassis frame, and one end of each of the lower radius rods A pair of left and right L-shaped levers pivotally attached to the other ends of the slods, and both ends are arranged to extend in the vehicle width direction and both ends are pivotally attached to the other ends of the left and right L-shaped levers, respectively. A hydraulic cylinder device comprising a piston rod having a piston at an intermediate portion and a cylinder supported by the chassis frame and containing the piston therein is provided, and the hydraulic cylinder device is used for steering the vehicle during high-speed traveling. In response to the steering, the left and right L-shaped levers are rotated to drive the left and right lower radius rods in opposite directions so as to rotate the rear axle housing around the other end pivot point of the upper radius rod. It is intended to provide a rear wheel steering device characterized in that it is configured.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. In the drawing, reference numeral 10 denotes a chassis frame of a vehicle such as a truck, which includes a pair of left and right side rails 12 extending in the vehicle longitudinal direction and a plurality of side rails extending in the vehicle width direction and having both ends fixed to the left and right side rails 12. And four cross members 14. Reference numeral 16 denotes a rear axle housing which supports a double tire 18 at both ends in the vehicle width direction, and reference numeral 20 denotes a first shackle link 2 at a front end thereof.
A main leaf spring (laminated leaf spring device) pivotally attached to the upper end of the second shackle link 26 by a pin 28 and pivotally attached to the lower end of the second shackle link 26 by a pin 24.

The first shackle link 22 is pivotally connected at its lower end to a front shackle bracket 32 by a pin 30, and the bracket 32 is fixed to the side rail 12 of the chassis frame 10. The upper end of the second shackle link 26 is pivotally attached to a rear shackle placket 36 by a pin 34, and the bracket 36 is fixed to the side rail 12 of the chassis frame 10. Therefore, the sprung load of the vehicle body acts on the front end of the main leaf spring 20 via the first shackle link 22 in the suspension direction, while the rear end of the main leaf spring 20 has the second shackle link. Via 26, it acts in such a way that the sprung load is supported. Reference numeral 38 denotes a helper leaf spring that is disposed above the main leaf spring 20 and that has front and rear ends thereof slidably in contact with a helper stopper 40 mounted on the side rail 12 when the load of the vehicle is equal to or greater than a set load. .

A rubber pad member 42, which is well shown in an enlarged side view of FIG. 3, is provided on the upper side surface and the lower side surface of the rear axle housing 16 near both ends in the vehicle width direction. An upper support member 44 having an inverted U-shaped side surface is mounted on the upper rubber pad member 42, and a lower rubber pad member 42 is mounted on a lower support member 46 having a U-shaped side surface. Have been. By inserting a pair of front and rear U-bolts 48 disposed in the front-rear direction intermediate portion of the main leaf spring 20 and the helper spring 38 through the upper and lower support members 44 and 46 and tightening a nut 50, the rear axle housing 16 Are connected to the main leaf spring 20 and the helper leaf spring 38 via rubber pad members 42, respectively.

The rubber pad member 42 has a pair of U-shaped steel back plates 52 and 54 each having a shallow U-shaped cross section in the longitudinal direction of the vehicle body. Shallow U-shaped rubber pad 5
6 is comprised. A pair of front and rear ear portions 58 project from the back metal 54 of the rubber pad member 42 on the side contacting the rear axle housing 16, and the ear portions 58 are fixed to the front and rear side surfaces of the rear axle housing 16 by welding or the like. It is fixed to the stop projection 60 by a bolt 62.

When the U bolt 48 is tightened as described above, the length of the leg portions of the upper and lower support members 44 and 46 that contact each other is set to a predetermined length in advance. Is applied with a predetermined compression force. (Note that, in the illustrated embodiment, the leaf spring device for rear wheel suspension includes the main leaf spring 20 and the helper leaf spring 38, but the helper leaf spring 38 may be omitted.)

The side rails 12 of the chassis frame 10
An upper radius rod 64 having a V-shaped plane is disposed along the center line in the front-rear direction of the vehicle body, and the apex of the radius rod is connected to a ball joint device 66 (or a rubber bush joint device having the same effect). The rear axle housing 16 is pivotally mounted on the upper side of a differential case 68 provided at a central portion of the rear axle housing 16, and the free ends of both legs of the rod are respectively connected to a ball joint device 70 (or a rubber bush type joint device having the same effect). It is pivotally attached to the side rail 12 (or the cross member 14) of the chassis frame 10 through the above.

As best shown in the side view of FIG.
A bracket 72 is fixed to a lower portion near both ends in the vehicle width direction of the rear axle housing 16 by welding or the like,
One end of a pair of left and right lower radius rods 76 is pivotally connected to the bracket 72 via a ball joint device 74 (or a rubber bush type joint device having the same effect).
The other end of each lower radius rod 76 is connected to one end of a pair of left and right L-shaped levers 82 whose bending portions are pivotally supported by pivots 80 on brackets 78 fixed to the web or side walls of the side rails 12, respectively, in the vehicle width direction. It is pivotally connected to the inner end of the extended lateral arm via a ball joint device 84 (or an equivalent rubber bush type joint device). A connecting rod 8 extending in the vehicle width direction is provided at the other end of the L-shaped lever 82, that is, at the rear end of a vertical arm extending in the vehicle longitudinal direction.
6 are respectively pivotally connected via ball joint devices 88 (or rubber bush type joint devices having the same effect).

One of the pair of L-shaped levers 82, for example, the left L-shaped lever 82 in the illustrated embodiment,
In a vertical arm extending in the front-rear direction of the vehicle body, a piston shaft 92 of a hydraulic cylinder device 90 forming a rear-wheel steering actuator is provided at an intermediate portion between the pivot 80 and the ball joint device 88 with a ball joint device 94 (or the same effect). Rubber bush type joint device). Further, a cylinder 96 of the hydraulic cylinder device 90 is supported by the bracket 78 on the chassis frame 10 via a ball joint device 98 (or a rubber bush type joint device having the same effect).

The ball joint devices 66, 70, 7
Examples of specific configurations of 4, 84, 88, 94 and 98 are illustrated in FIG. In the figure, reference numeral 100 denotes one member that causes relative rotation displacement, for example, the upper radius rod 6.
4, a lower radius rod 76, a bracket 72, a connecting rod 86, a piston shaft 92, and a shaft supporting portion formed on the hydraulic cylinder 96. Reference numeral 102 denotes the other member such as the chassis frame 10, the L-shaped lever 82, This is a ball seat supporting portion formed on the shear case 68. The shaft 106 having the spherical member 104 is supported by the one member 100, and the ball seat 108 slidably contacting the spherical member 104 is supported by the other member 102. With this configuration, one member 100 can freely rotate in the plane perpendicular to the axis of the shaft 106 and in the plane including the coaxial line within the angle ranges set respectively with respect to the other member 102.

FIG. 5 is a conceptual block diagram of a device for controlling the operation of the rear wheel steering actuator 90. Symbol 1 in the figure
Reference numeral 10 denotes a light pulse non-contact type steering angle sensor which is disposed on the steering shaft 112 to detect a steering angle.
14 is a vehicle speed sensor, 116 is a yaw rate sensor, 118
Is the steering angle signal of the steering angle sensor 110 and the vehicle speed sensor 114
Is a controller that receives the vehicle speed signal and the turning signal of the yaw rate sensor 116 to control the control valve 120 that operates the rear wheel steering actuator 90, and 122 is a hydraulic pump. When the steering wheel 124 is operated and the front wheels 126 are steered while the vehicle is running at high speed, the steering angle signal of the steering angle sensor 110, the vehicle speed signal of the vehicle speed sensor 114, and the turning signal of the yaw rate sensor 116 are received. The controller 118 issues a drive signal to the control valve 120 to operate the control valve. The high-pressure hydraulic oil discharged from the hydraulic pump 122 by the operation of the control valve 120 is supplied to the rear wheel steering actuator 90, and the actuator 90 expands or contracts according to the steering direction of the front wheel 126.

When the rear wheels are steered to improve the steering stability during high-speed running of the vehicle, the front wheels 12 are usually used.
The rear wheel 18 has a small steering angle, for example,
It is steered about 5 degrees. However, in relation to the steering of the front wheel 126, the rear wheel 18 is first steered by a slight angle in the direction opposite to the steering direction of the front wheel 126, and after a moment, the rear wheel 18 is moved to the front wheel 126.
It is also possible to employ another rear wheel steering system such as steering at a small angle in the same direction as the steering direction of the vehicle.

When the front wheels 126 are steered during high-speed running of the vehicle, the control valve 120 is operated by the command of the controller 118 as described above, and the rear wheel steering actuator 90 is extended or contracted. For example, when the actuator 90 extends, the left L-shaped lever 8 in FIG.
2 rotates clockwise around the pivot 80, and the left lower radius rod 76 connected to the lever is pulled to the rear of the vehicle body. At the same time, the left L-shaped lever 82
The right L-shaped lever 82 connected via a connecting rod 86 rotates clockwise around the pivot 80, and the lower right radius rod 7 connected to the lever is connected to the right L-shaped lever 82.
6 is driven forward of the vehicle body. As a result, the rear axle housing 16 is connected to the V-shaped upper radius rod 64.
Around the center of the ball joint device 66 at the apex of the front end, thereby improving the steering stability during high-speed running in a manner well known in the art.

When turning the rear axle housing 16 for steering, the shallow U-shape in the rubber pad member 42 interposed between the vicinity of both ends in the vehicle width direction of the rear axle housing 16 and the leaf spring devices 20 and 38. Since the rubber pad 56 having a shape is preliminarily given an appropriate pre-compression, the rubber pad 56 flexibly generates a shearing deformation so that the leaf spring device 20 can be used.
And 38, the rear axle housing 16 can rotate relatively smoothly.

According to the configuration of the present invention, the rear wheel steering actuator 90 is provided with the rear axle housing 1 having a large impact displacement and close to the ground surface as in the previously proposed device.
6 and is supported by the chassis frame 10 which is much less vibrated and at a sufficiently high position from the ground surface, so that damage to the actuator 90 due to impact or flying stones is prevented, and durability and reliability are improved. Be improved.

Further, the relative rotational displacement between the leaf spring devices 20 and 38 and the rear axle housing 16 during the rear wheel steering is smoothly permitted by the shear deformation of the rubber pad 56 in the rubber pad member 42. , The rear axle housing 16 and the leaf spring device 20 during traveling are different from those having a member such as a spring seat and a slider that slides and displaces along an arc sliding surface during rear wheel steering as in the above-mentioned proposed device. The muddy water, gravel, pebbles, etc., which inevitably come into contact with the connecting portion with the 38, do not hinder the smooth relative displacement between the two and cause no abrasion, so that durability and reliability are excellent, and rear wheel steering is performed. Since the capacity of the actuator and the capacity of the hydraulic control valve and the hydraulic power source attached thereto can be relatively reduced, the weight and the manufacturing cost are reduced. There is an advantage that can be reduced.

The vertical displacement of the rear axle housing 16 with respect to the chassis frame 10 during the straight running of the vehicle and the turning movement at the time of steering is of course performed in such a manner that the leaf spring devices 20 and 38 receive a load. The upper and lower radiator rods 16 perform a parallel linking motion by an upper radius rod 64 and a lower radius rod 76. Further, the upper radius rod 64 is connected to the ball joint device 6.
6 and 70 (or equivalent rubber bushing type joint device) are pivotally connected to the rear axle housing 16 and the chassis frame 10, and the lower radius rod 76 is similarly ball jointed device 74 and 84 (or equivalent rubber bush type joint device). ), The rear axle housing 16 is pivotally attached to the L-shaped lever 82 pivotally supported by the chassis frame 10, so that the rear axle housing 16 tilts to the left or right or rolls when running or turning on an uneven road. However, the displacement is not hindered.

Further, in the case of this embodiment, the sprung load of the vehicle is the first end of the main leaf spring 20 at the front end.
The rear shackle link 22 acts in the suspension direction, and the rear end of the rear shackle link 26 acts in the lower support direction. The jig 16 works to return to the neutral position, and there is an additional advantage that the rudder angle can be easily maintained.

Next, a second embodiment of the present invention will be described with reference to a schematic plan view of a main part of FIG. As shown, the piston shaft 92 of the rear wheel steering actuator 90 is connected via a ball joint device 94 to an extension 82 'of a vertical arm extending rearward of the vehicle body of one of the L-shaped levers 82. In other words, the pivot shaft 80 of the L-shaped lever 82 is different from the first embodiment in that the piston shaft 92 is pivotally attached to a portion farther than the pivot point of the connecting rod 86. The configuration is substantially the same as the first embodiment.

According to the configuration of the second embodiment, the capacity of the rear wheel steering actuator 90 can be made smaller than that of the actuator 90 of the first embodiment, and the capacity of the accompanying hydraulic control valve and the pressure oil source are of course smaller. Has the additional advantage that overall manufacturing costs and weight can be further reduced.

Further, a third embodiment of the present invention will be described with reference to a schematic plan view of a main part of FIG. As shown in the figure, both ends in the vehicle width direction of the piston shaft 92 of the rear wheel steering actuator 90 are attached to the vertical arms extending rearward of the vehicle body of the pair of left and right L-shaped levers 82 via the same ball joint device 128 as described above. And the piston shaft 92 also serves as the connecting rod 86 in the first embodiment. Further, a cylinder 96 for storing a piston 130 fixed or integrally formed at a substantially central portion of the piston shaft 92 in the vehicle width direction is provided on a cross member 132 of the chassis frame 10 with a ball joint device 98 (or the same effect). (A rubber bush type joint device). The configuration other than the above is substantially the same as the first embodiment.

According to the configuration of the third embodiment, the first
In addition to the various effects and advantages provided by the embodiments,
Since the connecting rod 86 in the first embodiment is omitted, there is an additional advantage that the structure is greatly simplified, thus further reducing manufacturing costs and weight.

In each of the above embodiments, a vehicle having a single rear axle is illustrated. However, in the case of a vehicle having two rear axles, the same rear wheels as described above are provided on both the rear front axle and the rear rear axle. A steering device is provided. Also, in a rear two-axle vehicle, one of the rear axles is often configured as a dead axle that does not transmit driving force, but the steering device itself is substantially equivalent to the illustrated drive shaft.

In all of the above embodiments,
Although a hydraulic cylinder device is illustrated as the rear wheel steering actuator 90, it is obvious that an appropriate actuator such as a rack and pinion type actuator and a screw / nut type actuator can be adopted.

[0031]

As described above, the rear wheel steering device such as a truck according to the present invention holds a chassis frame, a rear axle housing supporting rear wheels at both ends in a vehicle width direction, and the rear axle housing from above and below. A leaf spring device fastened to the rear axle housing by a tightening device such as a U-bolt via a rubber pad member, and both ends in the vehicle longitudinal direction pivotally attached to the chassis frame via shackle links, respectively, a center in the vehicle longitudinal direction. An upper radius rod, one end of which is pivotally connected to the center portion of the rear axle housing in the vehicle width direction and the other end of which is pivotally connected to the chassis frame, both sides of the front-rear center line of the vehicle body A pair of left and right lower radius rods, each of which is arranged substantially symmetrically with one end thereof and pivotally connected to the rear axle housing, A pair of left and right L-shaped levers pivotally supported on the arm and each having one end pivotally connected to the other end of the lower radius rod, extending in the vehicle width direction, and having both ends thereof connected to the left and right L-shapes. A connecting rod pivotally connected to the other end of the L-shaped lever, and an L-shaped lever supported by the chassis frame and connected to one of the L-shaped levers in response to steering and steering of the vehicle during high-speed running. By rotating the other L-shaped lever via the lever and the connecting rod, the left and right lower radius rods are driven in opposite directions, and the rear axle housing is rotated about the other end pivot point of the upper radius rod. Characterized by having one rear wheel steering actuator to
The rear wheel steering actuator and the member connecting the leaf spring device and the rear axle housing have the advantages of excellent durability and reliability and low manufacturing cost.

In the rear wheel steering apparatus, the rear wheel steering actuator may be configured such that the one L-shaped lever is pivotally connected to a chassis frame with respect to a pivot axis of the one L-shaped lever at a portion farther from a pivot point of the connecting rod. The configuration characterized in that the rear wheel steering actuator is connected to the rear wheel steering actuator has an advantage that the required capacity of the rear wheel steering actuator can be reduced and the manufacturing cost and weight thereof can be reduced.

Further, the present invention provides a vehicle frame, a rear axle housing supporting rear wheels at both ends in a vehicle width direction, and a tightening device such as a U bolt via a rubber pad member sandwiching the rear axle housing from above and below. A leaf spring device fastened to a rear axle housing and having both ends in the vehicle front-rear direction pivotally attached to the chassis frame via shackle links, one end of the rear axle housing disposed along a vehicle center line in the vehicle front-rear direction. An upper radius rod pivotally attached to a center portion in the vehicle width direction and having the other end pivotally attached to the chassis frame, and one end of each of the rear axles disposed substantially symmetrically on both sides of a longitudinal centerline of the vehicle body. A pair of left and right lower radius rods pivotally mounted on the housing, one end of each of which is pivotally supported on the chassis frame and has A pair of left and right L-shaped levers pivotally attached to the other ends of the radius rods, and both ends thereof are arranged to extend in the vehicle width direction and both ends are pivotally attached to the other ends of the left and right L-shaped levers, respectively. A hydraulic cylinder device comprising a piston rod provided with a piston in an intermediate portion and a cylinder supported by the chassis frame and containing the piston therein is provided. The hydraulic cylinder device is capable of steering the vehicle during high-speed traveling. In response to steering, the left and right L-shaped levers are rotated to drive the left and right lower radius rods in opposite directions so as to rotate the rear axle housing around the other end pivot point of the upper radius rod. A connecting rod for simultaneously driving the left and right L-shaped levers at the time of rear wheel steering constitutes a rear wheel steering actuator. Because it is also used by the piston rod of the hydraulic cylinder device that simplifies the structure is achieved. As a result, it is possible to provide an inexpensive and lightweight rear wheel steering device that is excellent in durability and reliability.

[Brief description of the drawings]

FIG. 1 is a main part plan view showing a first embodiment of the present invention.

FIG. 2 is a side view of the rear wheel steering device shown in FIG.

FIG. 3 is an enlarged side view showing, in an enlarged manner, a connecting portion between a leaf spring device and a rear axle housing shown in FIG. 2;

FIG. 4 is a sectional view showing a specific structure of the ball joint device in FIGS. 1 and 2;

FIG. 5 is a schematic configuration diagram of an operation control device for a rear wheel steering actuator in FIG. 1;

FIG. 6 is a main part plan view showing a second embodiment of the present invention.

FIG. 7 is a plan view of a main part showing a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 chassis frame 12 side rail 16 rear axle housing 20 main leaf spring (laminated leaf spring device) 42 rubber pad member 64 upper radius rod 76 lower radius rod 82 L-shaped lever 86 connecting rod 90 rear wheel steering actuator

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 2-125480 (JP, U) JP-A 4-22373 (JP, U) JP-A 62-15085 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) B62D 7/14

Claims (3)

(57) [Claims] 1. A rear axle housing supporting rear wheels at both ends in a vehicle width direction, a rubber pad member sandwiching the rear axle housing from above and below, and fastened to the rear axle housing by a tightening device such as a U-bolt. And a leaf spring device pivotally attached to the chassis frame via shackle links at both ends in the vehicle longitudinal direction, and disposed along a vehicle longitudinal centerline at one end thereof in the vehicle width direction center of the rear axle housing. An upper radius rod pivotally attached to the vehicle body portion and the other end pivotally attached to the chassis frame, and disposed approximately symmetrically on both sides of a longitudinal centerline of the vehicle body, and each end pivotally attached to the rear axle housing. A pair of left and right lower radius rods, each of which is pivotally supported on the chassis frame and has one end connected to the lower radius rod. A pair of left and right L-shaped levers pivotally attached to the ends, connecting rods extending in the vehicle width direction and having both ends pivotally attached to the other ends of the left and right L-shaped levers, respectively; The above L
The left and right lower radius rods are connected to one of the L-shaped levers by turning the other L-shaped lever through the same L-shaped lever and the connecting rod in response to the steering and steering of the vehicle during high-speed traveling. A rear wheel steering device, such as a truck, comprising one rear wheel steering actuator that drives the rear axle housing around the other end pivot point of the upper radius rod by driving in the opposite directions. . 2. The vehicle according to claim 1, wherein the rear wheel steering actuator is connected to the one of the L-shaped levers at a portion farther from a pivot point of the connecting rod with respect to a pivot axis of the one of the L-shaped levers with respect to a chassis frame. The rear wheel steering device according to claim 1, wherein the rear wheel steering device is a truck. 3. The rear axle housing is fastened to the rear axle housing by a tightening device such as a U bolt via a chassis frame, a rear axle housing supporting rear wheels at both ends in a vehicle width direction, and a rubber pad member sandwiching the rear axle housing from above and below. And a leaf spring device pivotally attached to the chassis frame via shackle links at both ends in the vehicle longitudinal direction, and disposed along a vehicle longitudinal centerline at one end thereof in the vehicle width direction center of the rear axle housing. An upper radius rod pivotally attached to the vehicle body portion and the other end pivotally attached to the chassis frame, and disposed approximately symmetrically on both sides of a longitudinal centerline of the vehicle body, and each end pivotally attached to the rear axle housing. A pair of left and right lower radius rods, each of which is pivotally supported on the chassis frame and has one end connected to the lower radius rod. A pair of left and right L-shaped levers pivotally attached to the ends, and both ends are arranged to extend in the vehicle width direction and both ends are pivotally attached to the other ends of the left and right L-shaped levers, respectively, and are provided at an intermediate portion. A hydraulic cylinder device including a piston rod having a piston and a cylinder supported by the chassis frame and containing the piston therein is provided. The hydraulic cylinder device responds to steering and steering of the vehicle during high-speed traveling. Then, the left and right L-shaped levers are rotated to drive the left and right lower radius rods in opposite directions so as to rotate the rear axle housing around the other end pivot point of the upper radius rod. A rear wheel steering device such as a truck.