JPH0558331A - Rear wheel steering system for two-axle vehicles - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To reduce the turning radius of a large rear two-axle vehicle to make it easier to change direction in tight spaces and to make sharp turns on narrow roads. [Structure] A front rear axle housing 12 and a rear rear axle housing 14, which are arranged in parallel in the vehicle front-rear direction and support rear wheels at both ends of the chassis frame 10, and front and rear ends of the front rear axle housing and the rear rear axle housing. Left and right equalizer beams 38 pivotally attached to the rear axle housing, and a saddle member 2 for slidably supporting a substantially central portion of the equalizer beams in the vehicle longitudinal direction.
8 and one end thereof is pivotally attached to the chassis frame or the saddle member and the other end is pivotally attached to the front rear axle housing or the rear rear axle housing, and its expansion and contraction causes the rear axle housing to rotate and steer.
In the rear wheel steering system for a rear two-axle equipped with the No. 4, the turning radius can be effectively reduced by steering the front and rear rear axle housings in the direction opposite to the steering direction by the pressure response device.

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 system suitable for use in a heavy load rear two-axle vehicle, particularly a rear two-axle crane vehicle.

[0002]

2. Description of the Related Art Conventionally, in a heavy-duty truck, particularly a crane vehicle, a rear two-axle vehicle having rear front wheels and rear rear wheels has been widely adopted in a rear portion of a chassis frame. In the case of a normal rear two-axle mobile crane, a front rear axle housing that supports the rear front wheels at both ends in the vehicle width direction and a rear rear axle housing that supports the rear rear wheels at both ends in the vehicle width direction have a chassis frame. Are connected to each other by a pair of left and right equalizer beams arranged in the front-rear direction of the vehicle body, and the equalizer beams freely rotate around their respective central portions around a fixed axis extending in the vehicle width direction. It is movably supported by a saddle member. Further, the saddle member is directly attached to the chassis frame via a suspension spring or without using a suspension spring. In the normal rear two-axle mobile crane, the equalizer beam can be vertically rotated about an axis extending in the vehicle width direction, but the equalizer beam is not rotated about a vertical axis. The front rear axle housing and the rear rear axle housing, which are connected to each other by a pair of left and right equalizer beams, are steered because they are supported by the saddle member and do not move relative to the saddle member in the front-rear direction. It is configured not to be. On the other hand, the rear two-axle mobile crane has a large turning radius because the wheelbase between the front and rear wheels is large in order to ensure the stability of crane work.
There are problems that it is difficult to change the direction at a narrow construction site, and that it is not easy to turn left and right on narrow roads and run on hairpin curves.

[0003]

SUMMARY OF THE INVENTION The present invention was devised in view of the above circumstances. Steering of the rear wheels of a rear two-axle reduces the turning radius of the two-wheeled rear axle to change the direction at a narrow work site. The purpose is to facilitate left and right turns on narrow roads.

[0004]

In order to achieve the above-mentioned object, the present invention has a rear frame of a chassis frame and a rear wheel at both ends in the vehicle width direction, which are arranged side by side in the longitudinal direction of the vehicle body. A supported front rear axle housing and a rear rear axle housing, left and right equalizer beams which are arranged along the chassis frame in the vehicle front-rear direction and whose front and rear ends are pivotally attached to the front rear axle housing and the rear rear axle housing, respectively. A saddle member mounted on a chassis frame and supporting a substantially central portion of the equalizer beam so as to be freely slidable in a vehicle longitudinal direction; one end pivotally attached to the chassis frame or the saddle member and the other end It is pivotally attached to the front rear axle housing or the rear rear axle housing, and its expansion and contraction allows the rear axle housing to Proposes a rear wheel steering apparatus for biaxial wheel after characterized by comprising comprises a pressure responsive device for steering is Mawarido the ring.

[0005]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. In the drawings, reference numeral 10 is a chassis frame of a mobile crane, of which only a part is shown, and 12 and 14 are front parts that are juxtaposed in the rear part of the chassis frame 10 at appropriate intervals in the front-rear direction of the vehicle body. A rear axle housing and a rear rear axle housing, 16 is a rear front wheel of a double tire type supported at both ends of the front rear axle housing 12 in the vehicle width direction, and 18 is a double tire supported at both ends of the rear rear axle housing 14 in the vehicle width direction. Rear rear wheels of the mold, 20 is a pair of left and right leaf spring devices arranged on both sides of the chassis frame 10 at an intermediate portion of the front and rear rear axle housings 12 and 14, and 22 is a front portion of the leaf spring devices 20. A front spring support bracket for pivotally supporting the eyeball portion formed at the end portion (indicated by arrow F in FIGS. 1 and 2), 4 is a rear spring support bracket that supports a sliding pin 26 that abuts on the upper surface of the rear end portion of the leaf spring device 20, and 28 is a fastener such as a U-bolt 30 at a substantially central portion of the leaf spring device 20. A fixed saddle member having a thin cross section, 32 is a hollow hole 3 pivotally supported by the saddle member 28 via a trunnion 34 having an axis in the vehicle width direction and extending in the vehicle body front-rear direction.
6 is a beam supporting member, 38 is the beam supporting member 3
2 is a pair of left and right equalizer beams fitted so as to be freely slidable in the front-rear direction of the vehicle body in each of the two hollow holes 36, and each equalizer beam 38 has its front and rear end portions shown in FIG. Ball joints 40 and 4 as described
Front and rear rear axle housing 1 via 2
It is pivotally attached to the lower part of 2 and 14.

As shown in FIG. 2, a pressure responsive device 44 composed of a pair of left and right hydraulic cylinders is provided.
Each pressure responder 44 has its cylinder 46 pivotally attached to the saddle member 28 via a ball joint and the free end of a piston shaft 48 is pivotally attached to the lower portion of the front rear axle housing 12 via a ball joint. ing. Further, a front radius rod 50 and a rear radius rod 52 are arranged along the longitudinal centerline OO of the vehicle body. The front radius rod 50 is pivotally attached at its front end to the center of the lower portion of the front rear axle housing 12 via a ball joint 54 and at its rear end to the lower portion of the chassis frame 10 via a ball joint 56. ing. Further, the rear radius rod 52 has a front end portion thereof via a ball joint 58 so that the chassis frame 10 is
A ball joint 6 which is pivotally attached to the lower part of the
It is pivotally attached to the lower part of the rear rear axle housing 14 via 0. During normal operation of the vehicle, the left and right equalizer beams 38 are fixed to the beam support member 32 by lock pins 62, as shown in FIG. Further, the pair of hydraulic cylinders 44 are
Normally, both side chambers of the piston are in communication with the oil tank through a hydraulic pressure switching valve (not shown) and are in a rest state. However, when steering of the rear front wheels 16 and the rear rear wheels 18 is desired, the driver operates the hydraulic pressure switching valve. By communicating the pressure oil source
One hydraulic cylinder 44 extends in association with steering of a steering wheel (not shown), while the other hydraulic cylinder 44 contracts, that is, operates in opposite directions.

In the above structure, the equalizer beam 38 is normally fixed by the lock pin 62 so as not to be displaced relative to the beam support member 32 in the longitudinal direction of the vehicle body. At this time, the front and rear rear axle housings 12 and 14 are substantially orthogonal to the vehicle longitudinal direction center line OO as shown in the schematic plan view of FIG. Are both inactive and held in a neutral state. Therefore, the rear front wheel 16 and the rear rear wheel 18 are not steered even when the steering wheel (not shown) is steered in any of the left and right directions while the vehicle is traveling straight, and the turning radius is large. Next, when changing the direction at a narrow work site or making a sharp turn or a left turn or a right turn on a narrow road, first remove the lock pin 62 to release the fixing between the equalizer beam 38 and the beam support member 32. The equalizer beam 38 is adapted to be freely slidable in the front-rear direction of the vehicle body. For example, when the steered wheels are steered to the right in order to turn the vehicle to the right, the hydraulic switching valve operates in association with the steered steering, and as shown in FIG.
4 expands and the left hydraulic cylinder 44 contracts. Therefore, as illustrated, the front rear axle housing 12 and the rear rear axle housing 14 are respectively steered to the left. By steering the steering wheel to the right, the rear front wheel 16 and the rear rear wheel 18 supported by the front and rear rear axle housings are steered in the opposite phase, that is, to the left.
The turning radius is effectively reduced. Along with the steering rotation of the front and rear rear axle housings 12 and 14, the left and right equalizer beams 38 are respectively moved to the beam support members 32.
With respect to the front and rear directions of the vehicle body, and in opposite directions. Normally, when the steered wheels are fully steered, the steering angles of the rear front wheels 16 and the rear rear wheels 18 are set to about 3 ° to 5 °, and such a rear wheel steering angle provides a sufficient turning radius. Can be reduced.

The operating pressure oil supplied from the hydraulic switching valve to the left and right hydraulic cylinders 44 in relation to the steering operation of the steered wheels is reversed from that described above, so that the steering direction of the steered wheels and the rear direction can be changed. When the steering direction is in phase with the steering wheel, that is, when the steered wheels are steered to the left, the rear wheels can be steered to the left as well. By steering the rear wheels in-phase in this manner, the vehicle can be run in an oblique direction, that is, can be run to the diagonal direction, and there is an advantage that the vehicle can be easily moved in a narrow work site or the like. Further, as a concrete means for simultaneously realizing the rear-wheel reverse-phase steering for changing the direction of the vehicle and the rear-wheel in-phase steering for the oblique traveling, that is, the crab traveling, as an example, the operating pressure from the pressure oil source is used. In the hydraulic oil circuit between the hydraulic switching valve that supplies oil to the pair of left and right hydraulic cylinders 44 related to the steering operation of the steered wheels, and the hydraulic cylinder, the operating pressure oil is A known switching valve for reversing the flow may be provided.

Further, in the illustrated embodiment, the saddle member 28 for supporting the equalizer beam 38 via the beam supporting member 32 is connected to the chassis frame 10 via the leaf spring device 20, but the leaf plate is not shown. The spring device 20 can be omitted, and the saddle member 28 can be directly connected to the chassis frame 10. The hydraulic cylinder 44 has one end pivotally attached to the saddle member 28 and the other end pivotally attached to the front rear axle housing 12.
0 or a structural member integral therewith, and the other end can be pivotally connected to the rear rear axle housing 14.

[0010]

As described above, the rear wheel steering system for a rear two-axle vehicle according to the present invention is provided in the rear portion of the chassis frame side by side with a space in the longitudinal direction of the vehicle body. A front rear axle housing and a rear rear axle housing that support rear wheels at both ends, and left and right sides pivotally attached to the front rear axle housing and the rear rear axle housing with front and rear ends of the front rear axle and rear axle arranged along the chassis frame in the vehicle longitudinal direction. An equalizer beam, a saddle member mounted on the undercarriage frame and supporting a substantially central portion of the equalizer beam so as to be freely slidable in the vehicle longitudinal direction, and one end thereof is pivotally attached to the undercarriage frame or the saddle member. And the other end is pivotally attached to the front rear axle housing or the rear rear axle housing, and by expansion and contraction of the rear axle axle housing. A structure that is equipped with a pressure response device that rotates and steers the housing, and a structure that can easily change the direction at a narrow work site and turn left or right on a narrow road. Since it is possible to provide a two-wheeled vehicle, it is industrially beneficial.

[Brief description of drawings]

FIG. 1 is a perspective view of an essential part showing an embodiment of the present invention.

FIG. 2 is a plan view of a main part as viewed from below in FIG.

FIG. 3 is a partial cross-sectional view taken along the line III-III in FIG.

FIG. 4 is a schematic plan view showing aspects of front and rear rear axle housings during normal traveling.

FIG. 5 is a schematic plan view showing a rear wheel steering mode at the time of steering the vehicle to the right.

[Explanation of symbols]

 10 Chassis frame 12 Front rear axle housing 14 Rear rear axle housing 16 Rear front wheel 18 Rear rear wheel 20 Lap leaf spring device 28 Saddle member 32 Beam support member 38 Equalizer beam 44 Pressure response device

Claims (1)

[Claims] 1. A front rear axle housing and a rear rear axle housing, which are arranged side by side in the front-rear direction of the vehicle body at intervals in the vehicle front-rear direction and support rear wheels at both ends in the vehicle width direction, and along the vehicle body frame. The left and right equalizer beams, which are arranged in the front-rear direction of the vehicle body, and whose front and rear ends are pivotally attached to the front rear axle housing and the rear rear axle housing, and the substantially central portion of the equalizer beam mounted on the chassis frame, are attached to the vehicle body. A saddle member that is supported so as to be freely slidable in the front-rear direction, one end of which is pivotally attached to the chassis frame or the saddle member and the other end of which is pivotally attached to the front rear axle housing or the rear rear axle housing. And a pressure responsive device for rotating and steering the rear axle housing. A rear wheel steering device for a rear two-axle vehicle, characterized in that