JPH0732832A - Rear suspension system - Google Patents

Abstract

PURPOSE:To provide a rear suspension system which enables the enhancement of the travel performance by simplification of the structure and reduction in the unsprung mass and makes it possible to prevent the occurrence of oversteering during travel on a curved road. CONSTITUTION:The rear suspension system comprises a dead axle 20 for supporting drive wheels 38, 40, a first pair of longitudinal beam members 42, 44 disposed at lateral side portions of differential gears in opposed and parallel relation to each other, a pair of second beam members 46, 48 adjacently secured to frontward ends of the pair of longitudinal beam members 42, 44 and extending from the longitudinal beam members in the frontward/inward direction and connected to each other at the forward ends and accordingly connected at the forward ends to a chassis in the form of a joint, a lateral beam member 54 connecting the longitudinal beam members at the back of the wheels, and a limiting mechanism for limiting their relative lateral movements which is disposed between the dead axle and the chassis. The differential gears are mounted to the chassis or vehicle body.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a rear suspension of a lightweight type suitable for use in light and medium-duty truck buses with a chassis. <Prior Art> Attempts have been made to reduce the unsprung mass to improve ground contact, and the prior art is well known by the applicant and the prior art on which the subject invention is based. In his own US Pat. No. 4,343,37
5 and 4,362,221. Further, prior to the above patents, the following early US patents 1,394,099 and Lanceden patents and 2,03
There is a patent No. 2,963 Narinja. These early patented suspensions were beam-type suspensions with articulated connections to the chassis, commonly referred to as dead axle types, in that the rear drive wheels and vehicle body were supported via appropriate spring members. It is a thing. <Problems to be Solved by the Invention> However, the conventional rear suspension illustrated in the above patent has succeeded in heavy-duty heavy vehicles, but has the drawback of being heavier and more expensive in light and medium-duty vehicles. . In view of the above, the present invention not only lowers the floor level of a vehicle to be applied to facilitate access (proximity) to the ground, but also has a simple structure and reduces the unsprung mass of the suspension to reduce vehicle fuel consumption and other traveling conditions. In addition to improving performance and reducing vehicle vibration, the dead axle type beam suspension is articulated to the chassis for linking the oversteering that tends to occur in vehicles on curved roads. It is an object of the present invention to provide a rear suspension that can be prevented by using the. Incidentally, US Patent No. 2,
No. 234,025 Delat Patent, No. 4,589,67
No. 7, Machinski and 4,802,689 Hoffmann patents show a so-called Watts type link structure, but all of them are dead axle type (especially one joint connection point). ), And the link structure itself is different, and does not mention anything about the problem of over-steering. <Means for Solving Problems> A first aspect of the rear suspension of the present invention for achieving the above-mentioned object is to connect a dead axle supporting a drive wheel and a front end of the axle to each other so that a vehicle body is mounted. A chassis for supporting, a differential mounted on the chassis, having one input shaft and a pair of output shafts, and drivingly connecting the output shaft and the wheels by the pair of shafts, and a chassis on the dead axle. A rear suspension comprising a spring device supporting the first and second longitudinal beam members, wherein the dead axles are arranged parallel to each other on the lateral sides of the differential and face each other; Fixed adjacent to the front end of the, extending inward from the longitudinal beam member, and having its tip end connected and articulated to the chassis at the tip end. A pair of beam members and a transverse beam member which is connected to the first pair of longitudinal beam members at the rear of the wheel, and a second rear suspension of the present invention is the first suspension described above. In the rear suspension of the invention described above, a wheel support sleeve is provided which is mounted on each of the longitudinal beam members and is coaxial with the output shaft of the differential in the lateral direction, and the drive shaft is extended through the sleeve, A wheel support shaft structure adapted to move in the vertical direction is added, and the third rear suspension of the present invention is the same as the rear suspension of the first invention, and is disposed between the dead axle and the chassis. The rear suspension of the fourth aspect of the present invention is the same as the rear suspension of the third aspect of the present invention. A mechanism for limiting the relative lateral movement of the first beam member and a first link member pivotally supported in the vehicle center direction at an intermediate point of the lateral beam member; A second and a third link member, which are articulated to the link member, whose outer ends are respectively articulated to the chassis, and whose outer ends are respectively articulated to the chassis;
In the rear suspension of the invention, the relative lateral movement limiting mechanism in the rear suspension of the third invention is equidistant from the first link member pivotally supported at the midpoint of the lateral beam member and the midpoint. It has second and third link members each having an inner end articulated to the first link member and an outer end articulated to the chassis, and has a pivot point of the first link and a dead axle tip. The dead axle roll axis extending between the lateral axes of the articulation points of
The horizontal axis is aligned with the horizontal line or is positioned above the horizontal line at an upward angle, and the sixth rear suspension of the present invention is the same as the rear suspension of the first invention. A wheel support sleeve mounted on the directional beam member and provided with a wheel support sleeve coaxially with the output shaft of the differential in a lateral direction, the drive shaft extending through the sleeve, and moving in a direction perpendicular to the sleeve. A shaft structure and a relative lateral movement restricting mechanism for them arranged between the dead axle and the chassis are added. <Operation> Since the differential having the above-described structure is attached to the chassis or the vehicle body, the unsprung mass of the rear suspension is reduced. In addition, the dead axle having the above-described structure has a lightweight and sturdy structure, and is free from bending and twisting in the vertical direction, thereby increasing the rigidity of the suspension. In addition, the lightweight and highly rigid wheel support shaft structure having the above configuration is installed on the dead axle, and as a result, the height of the dead axle is reduced and the height of the vehicle body is reduced.
Further, the relative lateral movement restricting mechanism having the above structure prevents the dead axle from moving laterally with respect to the chassis when the dead axle moves up and down. Further, the arrangement of the relative lateral movement limiting mechanism prevents the over-steering phenomenon while the vehicle is traveling on the curved road, which is caused by the relative vertical movement between the dead axle and the chassis. Embodiments With particular reference to FIGS. 1 and 2, the vehicle chassis is generally indicated at 10 and, although not shown in the drawings, the vehicle body is supported therein. The chassis 10 has a pair of vertical members 12 and 14, and has a C-shaped cross section as shown in FIG. The chassis 10 also has a front cross member 16 which is welded between the vertical members 12 and 14. Further, 18 is a rear cross member, which is on the chassis 10 and is arranged behind a rear suspension generally indicated by 20. As best seen in FIGS. 1 and 3, the differential is generally indicated at 22, and not shown in the drawings, but directly on the chassis 10 with a suitable bracket or on a vehicle body supported by the chassis 10. Installed in the structure. Therefore, the differential 22 is mounted so as to move vertically with respect to the rear suspension 20, together with the chassis 10 and the body. As with the prior art device, mounting the differential 22 on the chassis 10 or vehicle body reduces the unsprung mass of the rear suspension 20. The differential 22 has an input shaft 24 and a suitable universal joint 26.
Is connected to an engine-driven propeller shaft 28 via. Also, a pair of output shafts 30 and 32 on the differential 22 are connected to drive axles 34 and 36 via suitable universal joints, and then to rear wheels 38 and 40. Rear wheels 38 and 40 with drive axles 34 and 36 being the drive wheels
The means connected to will be described later in connection with FIG. An in-vehicle mounted disc brake is shown at 41 and the output shafts 30 and 3 of the differential 22 are shown.
2 or the drive axles 34 and 36 to properly brake the rear wheels 38, 40. It should be further noted that conventional outboard brakes can be mounted and used near the rear wheels 38 and 40. Rear suspension or dead axle 20
Is made up of several major synergistic components. In this case, the dead axle 20 can be said to be of the so-called cathedral shape, in which the first longitudinally extending pair of longitudinal beam members 42 and 44, outside the longitudinal members 12 and 14 of the chassis 10, It is arranged horizontally. The cross-sectional shapes of the longitudinal beam members 42 and 44 and other related members are of particular importance in making the suspension lightweight and robust. In particular, as clearly shown in FIGS. 3 and 4, each beam member has a hollow cross section, which is rectangular or ideally square. These shapes are in particular contrast to the tubular members used in the suspensions of the Lansden and Narinja patents previously mentioned, where they are subject to longitudinal bending and twisting, resulting in The rigidity is reduced, but there is no such fear. A second pair of beam members 46 and 48 are connected by butt welding to the front ends of the longitudinal beam members 42, 44, from which they extend forward, inwardly and through trunnion members 52 to the side of chassis 10. Concentrated in an apex joint 50 that is articulated to the material 16. Upper plate 4
The apex joint 50 is reinforced by properly fixing the lower plate 9 and the lower plate 51 to the beam members 46 and 48. The trunnion member 52 includes the beam member 4
Hard rubber bush 53 if possible between the ends of 6, 48
Install. The cross-sectional shape of the beam members 46 and 48 angled inward is such that the longitudinal beam member 4
Similar to cases 2 and 44. Lateral beam member 5
4 is attached to each of the longitudinal beam members 42-44 and is located forward of the rear ends of the longitudinal beam members. The cross-sectional shape of the transverse beam members 54 is generally similar to that of the longitudinal beam members 42 and 44. In order to lower the height of the rear suspension or dead axle and lower the floor of the vehicle body supported by the chassis 10, the dead axle 20 has a pair of eyelids of the same shape. Wheel support shaft structures 56 and 58 are provided and supported by individual longitudinal beam members 42 and 44. Since these wheel support shaft structures 56 and 58 have exactly the same shape, only one will be described. As clearly shown in FIG. 4, the support shaft structure 58 has a hollow structure, and the constituent members thereof include a pair of plate members 60 and 62, and the longitudinal beam member 44.
It is fixed by welding to the vertical inner and outer walls. The plate members 60 and 62 project vertically adjacent to each other and vertically above the longitudinal beam member 44, the upper end of which consists of a horizontal portion 64 and a forwardly inclined portion 66, the inclined portion 66 being the longitudinal beam. It terminates in an adjacent portion of member 44. As described above, the end portions 6 of the plate members 60 and 62 are
Inclining the 6 will remove unnecessary parts and reduce the weight of the dead axle.
Wheel support shaft structures 56 and 58, as clearly shown in FIG.
The uppermost end of the is higher than the bottom of the chassis 10 and extends upward. The pair of openings 68 arranged concentrically in the lateral direction is the first
Although only one can be seen, the wheel holding sleeve 70 enters the opening in the plate members 60 and 62, respectively, and welds around the joint between the sleeve 70 and the plate members 60 and 62 to form a plate. Properly fixed. To strengthen the wheel support axle structure 58 and other axle structures, the rear end of the inner plate member 60 is bent at a right angle to form a triangular portion 72 and welded to the front vertical surface of the transverse beam member 54. Fix it. Similarly, the rear end of the outer plate member 62 is also bent vertically and welded to the inner plate member 60. The two plate members 6
The front end of 0-62 is welded to the vertical inner wall of beam member 48 when angled inward at the juncture of longitudinal beam members 42-44 and beam members 46-48.
To further strengthen and enclose the wheel support shaft structure 58, an angled top plate 74 is provided on the plate member 60.
Are welded to the upper end portions 64 and 66 of 62 and 62. In addition, various stiffening plates are attached to strengthen the lightweight dead axle. That is, the joint between the longitudinal beam members 42-44 and the angled beam members 46-48 joined to the members 42-44 is spanned and further attached to the transverse beam member 54. Above all, as can be seen in FIG.
Lower stiffening plates 76, 78 angle beam members 46-48 with adjacent longitudinal beam members 42-44.
Is attached to the lower surface of and is connected to the joint between the members. Additional stiffening plates 80 and 82 are attached to the undersides of longitudinal beam members 42-44 and transverse beam member 54, respectively, spanning the juncture between these members. Note that the upper stiffening plate 80 extends posterior to the longitudinal beam members 42-44, while the lower stiffening plate 82 extends forward and is located immediately adjacent the wheel support axle structure 58. As is apparent from FIGS. 1 and 2, the longitudinal members 12 and 14 of the chassis 10 extend rearwardly beyond the rear suspension or dead axle 20. Suitable bracket 8
4 and 86 are attached to the longitudinal members 12, 14 so as to project laterally above the rear ends of the longitudinal beam members 42-44. A support member 88 is also mounted on the upper surface near the rear ends of the longitudinal beam members 42-44, and a suitable spring member, such as an air bag 90, is supported on the support member 88. The upper end of the air bag or spring member 90 is attached to the brackets 84 and 8
6, the chassis 10 and the vehicle body are supported on their dead axle 20 by means of their spring members. The mechanism for limiting the relative lateral movement between the dead axle 20 and the chassis 10 shown in the embodiments of FIGS. 1 to 3 and 6 is of the three linkage type. A mechanism of the above type is shown generally at 92, with the first link 94 attached to a laterally centered bracket 96 as a pivot with a spindle 98 oriented in the longitudinal longitudinal axis of the vehicle at its midpoint. And the bracket 96 is attached to the transverse beam member 54. The second and third links 100 and 102 have the same length, and their respective inner ends 104 and 106 allow the first link 94 to reach the midpoint of the spindle 9
Articulated at points equidistant from 8. FIG. 6 shows a state in which the linkage mechanism 92 is in a normal position when the chassis 10 and the dead axle 20 are laterally coaxial with each other and there is no relative movement between them. . At this time, the middle point of the first link 94 and the second and third points
The inner ends 104 and 106 of the links 100 and 102 are aligned along a perpendicular line 120 passing through the center. This array relationship changes when there is relative movement between the chassis and the dead axle. The second and third links 100 and 102
The outer ends 108 and 110 of the spindles 112 and 1
By 14 the spring is articulated so that this becomes the axis.
The bracket 8 is attached to the brackets 84 and 86.
4 and 86 are fixed to the chassis 10. Thus, the outer ends 108 and 110 are articulated to move with the chassis 10, while the first link 94 is articulated to move with the dead axle 20. As is apparent from FIG. 6, when the inner ends 104 and 106 of the second and third links 100 and 102 are aligned along the perpendicular 120, the second and third links 100 and 10 are aligned.
2 is almost horizontal. When the dead axle 20 moves vertically with respect to the chassis 10, the second and third links 1
The inner ends 104 and 106 of 00 and 102 are arcs 116 and 118 about the centers of spindles 112 and 114.
Draw and move. The runout or lateral movement of the inner ends 104 and 106 of the second and third links 100 and 102 is equal on the opposite side of the perpendicular 120, so that the first link 94 is represented by the spindle 98 while rotating. First to be
The midpoint of the link 94 in FIG. 1 prevents it from deviating from the normal 120 during the relative vertical movement between the chassis 10 and the dead axle 20. Therefore, the three linkage mechanism 92
This prevents any relative lateral movement between the chassis 10 and the dead axle 20. 2 and 7
As can be seen in the figure, the spindle 98 of the first link 94 of the three-linkage mechanism 92, which is a mechanism for limiting the relative lateral movement, is oriented in the longitudinal central axis direction of the vehicle.
The apex joint 50 is positioned at a right angle to the lateral axis 170 passing through the articulation connection point with the cross member 16.
Further, the roll shaft 171 in the dead axle 20 extending through the lateral shaft 170 and the spindle 98 is
As shown in FIG. 7, it is aligned with a horizontal line passing through the transverse axis 170 or above the horizontal line at an angle of (0
The position should be such that ~ 5 ° is good). This can be created by lifting the spindle 98 above the lateral axis 170 or by placing the lateral axis 170 below the spindle 98, which causes the roll of the dead axle 20 to roll. Axis 1
It is possible to prevent rotation around 71 and prevent oversteering caused by harmful steering force. Further, by mounting the spindle 98 on the dead axle 20 as described above, the inclination of the roll shaft 171 increases as the load on the vehicle increases, and the amount of understeer also increases. This property is beneficial in that the steering operation becomes discreet. 8 The mechanism for limiting relative lateral movement in the embodiment shown below is of the panhard rod linkage type and is generally indicated at 130. This includes a suitable panhard rod 132 articulated at its opposite ends to a transverse beam member 54 and to a bracket 134 mounted to the chassis 10 to provide the chassis 10
Lateral movement of dead axle 20 with respect to is prevented. Similarly, a suitable shock absorber 136 is mounted between dead axle 20 and chassis 10 to dampen its relative vertical movement. See FIG. 5 for details of how the wheels 38-40 are attached to the dead axle 20. As shown in FIG. 5, the wheel support sleeve 70 has a ring 138,
The flange 142 of the journal sleeve 140 is welded within the outer end of the sleeve 70 so that the appropriate stud member 14
It is attached to this by four. Hub 146 is supported and rotated by journal sleeve 140 via suitable bearing members 148 and 150. stud·
The shaft 154 is connected at its inner end to the drive axle via a suitable connection 156. The outer end of the stud shaft 154 is suitably secured to the outer journal 158, which in turn drives the drive axle. Stud member 160 is radial flange 1
62, and wheels 38-40 are also attached thereto using suitable nuts 164. <Effects of the Invention> Since the rear suspension of the present invention is configured as described above, it has the following effects. (1) Since the differential is attached to the chassis or the vehicle body, the unsprung mass of the rear suspension is reduced and the vehicle performance is improved. (2) The dead axle has a lightweight and sturdy structure, and is free from bending and twisting in the vertical direction, and the rigidity of the suspension can be enhanced. (3) The lightweight and highly rigid wheel support shaft structure is installed on the dead axle, and as a result, the height of the dead axle can be lowered and the height of the vehicle body can be reduced, thereby improving the vehicle stability. Contribute to. (4) The relative lateral movement limiting mechanism prevents the dead axle from moving laterally with respect to the chassis when the dead axle moves up and down. Further, by disposing the relative lateral movement limiting mechanism, it is possible to prevent the over-steering phenomenon while the vehicle is traveling on the curved road, which is caused by the relative vertical movement between the dead axle and the chassis, which contributes to the stable running of the vehicle. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 8 are plan views of an embodiment of the rear suspension of the present invention that is articulated to a vehicle chassis, and FIGS. 2 and 9 are front views thereof. 3 and 10 are rear views of the same, FIGS. 4 to 6 are views showing the main part, and FIG. 5 is a view showing the internal structure of A of FIGS. 1 and 8. FIG. 7 shows a layout of the roll shafts. 10: chassis, 12, 14; vertical members, 16, 18; horizontal members,
20; Rear suspension (dead axle) 2
2; differential, 24; input shaft, 26; universal joint, 28; propeller shaft, 3
0, 32; output shaft, 34, 36; drive axle, 38, 4
0; rear wheels, 42, 44; first pair of longitudinal beam members, 46, 48; second pair of beam members, 50; apex joints, 52; trunnion members, 54; transverse beam members, 56 , 58; Wheel support shaft structure, 60, 6
2; a set of plate members, 70; wheel support sleeve, 7
4; top plate, 76, 78, 80, 82; reinforcing plate, 84, 86; bracket, 88; support member,
90; Spring member, 92; Relative lateral movement restricting member (three linkage type), 94; First link, 98; Spindle, 100; Second link, 10
2; third link, 120; perpendicular, 112 ;, 114;
Spindle, 130; Relative lateral movement restriction member (panhard rod linkage type) 132; Panhard rod, 134; Bracket, 136; Shock
Absorber, 138; Ring, 140; Journal sleeve, 142; Flange, 146; Hub, 154; Stud shaft, 158; Outer journal, 16
0: Stud member, 162: Radial flange,
164; Nut. 170; lateral axis, 171; roll axis

Claims (1)

Claims: (1) A dead axle supporting a drive train, a chassis to which a front end of the axle is articulated to support a vehicle body, a chassis mounted on the chassis, and a pair of an input shaft and a pair. In the rear suspension, which has an output shaft of, a differential that drivably connects the output shaft and the wheel by a pair of shafts, and a spring device that supports the chassis on the dead axle, the dead axle is A first pair of longitudinal beam members arranged parallel to each other on the lateral sides of the differential, fixed adjacent to the front ends of the beam members, and inward from the longitudinal beam members. To the first pair of longitudinal beam portions extending rearwardly of the first pair of beam members connected to the chassis at their tips and articulated to the chassis at the tips. A rear suspension composed of a lateral beam member formed by joining materials. (2) A dead axle that supports the driving wheels, a chassis that supports the vehicle body by articulating the front ends of the axle, and a chassis that is mounted on the chassis and has one input shaft and a pair of output shafts. In a rear suspension including a differential that drivably connects the output shaft and the wheel by a pair of shafts and a spring device that supports a chassis on a dead axle, the dead axle may be a lateral side of the differential. A first pair of longitudinal beam members arranged parallel to each other in parallel to each other, fixed adjacent to the front end of the beam members, extending inward from the longitudinal beam member, and its tip. A second pair of beam members that are connected to each other and are articulated to the chassis at the tip, and a differential output shaft mounted on each of the longitudinal beam members. Direction wheel support sleeve is provided coaxially to, and stretching the drive shaft through the sleeve,
A wheel support shaft structure adapted to move in a direction perpendicular to the sleeve, and a lateral beam member connecting the first pair of longitudinal beam members at the rear of the wheel. Rear suspension. (3) A dead axle that supports the drive wheels, a chassis that is articulated at the front end of the axle and supports the vehicle body, and a chassis that is mounted on the chassis and that has one input shaft and a pair of output shafts. In a rear suspension including a differential that drivably connects the output shaft and the wheel by a pair of shafts and a spring device that supports a chassis on a dead axle, the dead axle may be a lateral side of the differential. A first pair of longitudinal beam members arranged parallel to each other in parallel to each other, fixed adjacent to the front end of the beam members, extending inward from the longitudinal beam member, and its tip. A second pair of beam members connected to each other and articulated to the chassis at the tip and a first pair of longitudinal beam members behind the wheel. Rear characterized and the beam member, that it has been composed with the dead axle and the mechanism for limiting the relative lateral movement thereof disposed between chassis-
suspension. (4) A dead axle that supports the drive wheels, a chassis that is articulated at the front end of the axle to support the vehicle body, and a chassis that is mounted on the chassis and that has one input shaft and a pair of output shafts. In a rear suspension including a differential that drivably connects between the output shaft and the wheel by a pair of shafts and a spring device that supports a chassis on the dead axle, the dead axle has a lateral side of the differential. A first pair of longitudinal beam members arranged parallel to each other on the directional side, fixed adjacent to the front ends of the beam members, extending forward and inward from said longitudinal beam members, and A lateral side connecting a second pair of beam members, the tips of which are connected and articulated to the chassis at the tips, and the first pair of longitudinal beam members behind the wheel. A beam member, a first link member disposed between the dead axle and the chassis, and pivotally supported at an intermediate point of the lateral beam member, and the first link having inner ends at equidistant points from the intermediate point. A second member, which is articulated to the member and whose outer ends are respectively articulated to the chassis,
A rear suspension comprising a mechanism for limiting relative lateral movement having a third link member. (5) A dead axle that supports the drive wheels, a chassis that is articulated at the front end of the axle, supports the vehicle body, and is mounted on the chassis and has one input shaft and a pair of output shafts. In a rear suspension including a differential that drivably connects the output shaft and the wheel by a pair of shafts and a spring device that supports a chassis on a dead axle, the dead axle may be a lateral side of the differential. A first pair of longitudinal beam members arranged parallel to each other in parallel to each other, fixed adjacent to the front end of the beam members, extending inward from the longitudinal beam member, and its tip. A second pair of beam members connected to each other and articulated to the chassis at the tip and a first pair of longitudinal beam members behind the wheel. A beam member and a relative lateral movement limiting member disposed between the dead axle and the chassis, wherein the relative lateral movement limiting mechanism is pivotally supported at an intermediate point of the lateral beam member. One link member and second and third link members each having an inner end articulated to the first link member and an outer end articulated to the chassis at equidistant points from the intermediate point, And a dead axle roll axis extending between the lateral axis of the pivotal point of the first link and the articulation point of the dead axle tip coincides with a horizontal line passing through the lateral axis or an upward angle above the horizontal line. -Rear characterized by being positioned in
suspension. (6) A dead axle supporting the drive wheels, a chassis in which the front ends of the axles are jointly connected to support the vehicle body, and a chassis mounted on the chassis that has one input shaft and a pair of output shafts. In a rear suspension including a differential that drivably connects the output shaft and the wheel by a pair of shafts and a spring device that supports a chassis on a dead axle, the dead axle may be a lateral side of the differential. A first pair of longitudinal beam members arranged parallel to each other in parallel to each other, fixed adjacent to the front end of the beam members, extending inward from the longitudinal beam member, and its tip. A second pair of beam members that are connected to each other and are articulated to the chassis at the tip, and a differential output shaft mounted on each of the longitudinal beam members. Direction wheel support sleeve is provided coaxially to, and stretching the drive shaft through the sleeve,
A wheel support shaft structure adapted to move vertically with respect to the sleeve, a transverse beam member connecting the first pair of longitudinal beam members behind the wheel support shaft structure, and the dead axle. A rear suspension comprising a mechanism arranged between the chassis to limit the relative lateral movement of the chassis.