GB2145673A

GB2145673A - Multiple axle suspension system

Info

Publication number: GB2145673A
Application number: GB08420085A
Authority: GB
Inventors: Gordon Andrew Morris
Original assignee: TRUNK TRAILER Co Ltd
Current assignee: TRUNK TRAILER Co Ltd
Priority date: 1983-08-12
Filing date: 1984-08-07
Publication date: 1985-04-03
Also published as: GB8321808D0; GB8420085D0

Abstract

Front and rear axes (1,3) e.g. of a trailer are rigidly attached to respective main beams (5,6) which are pivotable on cross shafts (10) which bear, via bolster springs (12), against opposite ends of common beams (14) which are mounted on the chassic (16) preferably at a single location by means of shaft (15). An equalising beam (7) is connected to the inner ends of the main beams (5,6) by pivotal links (89) and may carry, via resilient pivot (18), a middle axle (2) which is located by one or a pair of radius arms (20) so that it can float relative to the other axes. The suspension system permits relative twisting of the axes and ensures equal loading of each cross shaft (10). <IMAGE>

Description

SPECIFICATION Suspension System This invention relates to a suspension system.

Our Patent No. 2,004,235 relates to a tri-axle walking beam suspension having front and rear main beams each pivotally connected to the vehicle chassis and pivotally interconnected through an equalising beam. The three beams are mounted one on each axle of the vehicle.

While this arrangement has provided an excellent suspension system, for example for commercial trailers, it has not catered for twisting of the axles relative to one another, which can occur frequently in use. Further, this system is mounted directly on the vehicle chassis through spaced stools associated one with each of the front and rear beams, thus providing the possibility of unequal loading on each stool.

According to the present invention there is provided a suspension system for a vehicle and having front and rear parallel spaced axles having road wheels mounted thereon, each end portion of the front and rear axles being mounted on a respective main beam member, said main beam members being pivotally mounted on a common beam member which is mounted on the vehicle chassis at one or more locations intermediate the mountings of the main beam members on the common beam member.

Preferably the common beam member is mounted on the vehicle chassis at a single location.

Preferably the main beam members are mounted one at each end portion of the common beam member and the common beam member is mounted on the vehicle between them.

Preferably also the suspension system has a middle axle intermediate the front and rear axles and adapted to have road wheels mounted on it, and first and second connecting struts are provided, the first strut being pivotally mounted between one of the main beam members and an equalising member which is secured intermediate its ends to the middle axle, and the second strut being pivotally mounted between the other main beam member and the equalising member, the equalising member being connected to the vehicle chassis through a radius arm which allows the middle axle to move in an arc of a circle around the connection between the radius arm and the vehicle chassis.

Preferably also the main beam members are mounted on the common beam member through resilient connections, for example springs.

Further according to the present invention there is provided a walking beam suspension system for a vehicle and having front, middle and rear parallel spaced axles adapted to have wheels rotatably mounted thereon, in which each end of the front and rear axles is mounted on a respective main beam member at one end portion of the beam, first and second connecting struts each connected through pivot bearings to the other end of a respective main beam member and to a respective end of an equalising member which is secured intermediate its ends to the middle axle, the middle axle being connected to the vehicle through a radius arm which allows the middle axle to move in an arc of a circle around the connection between the radius arm and the vehicle, each of the main beam members being adapted to be pivotally connected intermediate its ends to the vehicle, and the equalising member being secured to the middle axle through a resilient mounting for absorbing twisting stresses between the equalising member and the middle axle.

Preferably the front and/or rear main beam members are resiliently connected with the vehicle.

The resilient mounting of the equalising member to the middle axle may be in the form of a bushing at a pivotal connection between the equalising member and a stool which is secured to the axle.

Thus the equalising member may pivot about an axis spaced from the middle axle.

The bushing may be of rubber such as Metalastik (Dunlop Trade Mark) or other resilient material.

Embodiments of this invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a side view of a suspension system of this invention on a 30 tonne commercial trailer; Figure 2 is a section on A-A of Figure 1; Figure 3 is a section on X-X of Figure 1; Figure 4 is a section on C-C of Figure 1; and Figure 5 is a side view of an alternative construction including a pair of radius arms.

Referring now to the drawings the suspension system of this embodiment of the invention is provided on a 30 tonne trailer and has front, middle and rear axles 1, 2 and 3, respectively. Wheels 4 are rotatably mounted on the axles on both sides of the trailer. The axles 1,2 and 3 are connected together by a walking beam arrangement of main beams 5 and 6 and an equalising beam 7, the main beams 5 and 6 being connected to the opposite ends, respectively, of the equalising beam 7 by means of pivotal links 8 and 9.

The front main beam 5 is welded at its front end portion to the axle 1 and the rear main beam 6 is welded at its rear end portion to the axle 3.

The main beams 5 and 6 are each pivotally connected intermediate their ends to a respective tubular cross-shaft 10 which is welded to a seat 11 against which bear a pair of bolster springs 12.

These springs 12 bear at their opposite ends against respective angled stools 13 bolted on the underside of a beam 14 through which a tubular shaft 15 passes. The shaft 15 also passes through a pair of I-beams 16 which form part of a load-bearing platform of the trailer. The suspension members and the platform are therefore interconnected through a single mounting location by means of the shaft 15.

A V-ring seal 25 is provided between each of the main beams 5, 6 and stepped portions of the cross-shaft 10.

The pivotal links 8 and 9 connecting the main beams 5, 6 and the equalising beam 7 are mounted on the beams 5, 6, 7 in similar manner to that described in our Patent No. 2,004,235.

The equalising beam 7 is apertured for passage of a bolt 18 within a sleeve 26 which is welded to a stool in the form of parallel plates 17. The stool 17 is welded to the middle axle 2. A Metalastik bush 19 fits around the sleeve 16 to provide a resilient bearing for the beam 7 on the stool 17.

In use, the middle axle 2 is maintained in its correct relative position to the other two axles by means of a radius arm 20 which is secured at one end to a lug 21 formed on a stool welded to the front axle 1 and at the other end to a bracket 22 welded to the axle 2. The connections at both ends are by means of Metalastik bearings, which allow the radius arm 20 to pivot at its connections while allowing limited twisting of the arm. The length of the radius arm may be adjusted by means of screw-threaded radius arm ends 24.

As the vehicle passes over bumps or undulations in the ground the load carrying capacity of each of the wheels is equalised by means of the interconnected beams, and the middle axle is allowed to float relative to the other axles in a path which is an arc of a circle having its centre at the point where the radius arm 20 is connected to the lug 21.

The broken lines in Figure 1 show the range of pivotal movement of the equalising beam 7 about the bolt 18 in response to upward movement of the rear axle 3.

Torsion and twisting of the middle axle 2 is absorbed in use by the Metalastik bush 19. The single-location mounting of the suspension to the vehicle through the shaft 15 ensures constant weight distribution on the suspension in that the loading on each cross-shaft remains equal at all times; this equal loading is thence transmitted equally to the axles.

Figure 5 shows an alternative arrangement for connecting the middle axle 2 to the vehicle chassis, in that a pair of parallel radius arms 20A and 20B are pivotally mounted at equally spaced intervals on the bracket 22 and on the lug 21 so as to form a parallelogram arrangement. This construction provides greater strength for the radius arm connection, this being especially important when the vehicle loads are heavy. The arrangement shown in Figure 5 operates in the same manner as that of Figures 1 to 4 and described above.

Modifications and improvements may be made without departing from the scope of the invention.

Claims

1. A suspension system for a vehicle and having front and rear parallel spaced axles having road wheels mounted thereon, each end portion of the axles being mounted on a respective main beam member, said main beam members being pivotally mounted on a common beam member which is mounted on the vehicle chassis at one or more locations intermediate the mountings of the main beam members on the common beam member.

2. A suspension system according to Claim 1, wherein the common beam member is mounted on the vehicle chassis at a single location.

3. A suspension system according to Claim 1 or 2, wherein the main beam members are mounted one at each end portion of the common beam member.

4. A suspension system according to any one of the preceding Claims, wherein the suspension system has a middle axle intermediate the front and rear axles and adapted to have road wheels mounted on it, and first and second connecting struts are provided, the first strut being pivotally mounted between one of the main beam members and an equalising member which is secured intermediate its ends to the middle axle, and the second strut being pivotally mounted between the other main beam member and the equalising member, the equalising member being connected to the vehicle chassis through a radius arm which allows the middle axle to move in an arc of a circle around the connection between the radius arm and the vehicle chassis.

5. A suspension system according to Claim 4, wherein a second radius arm is provided between the equalising member and the vehicle chassis and forming a parallelogram arrangement with the first radius arm.

6. A suspension system according to Claim 4 or 5, wherein the equalising member is secured to the middle axle through a resilient mounting for absorbing twisting stresses between the equalising member and the middle axle.

7. A suspension system according to any one of the preceding Claims, wherein the main beam members are mounted on the common beam member through resilient connections.

8. A suspension system according to Claim 7, wherein the resilient connections are provided by bolster springs.

9. A suspension system according to Claim 1, substantially as herein before described with reference to and as shown in Figures 1 to 4 of the accompanying drawings.

10. A suspension system according to Claim 1, substantially as herein before described with reference to Figure 5 of the accompanying drawings.

11. A walking beam suspension system for a vehicle and having front, middle and rear parallel spaced axles adapted to have wheels rotatably mounted thereon, in which each end of the front and rear axles is mounted on a respective main beam member at one end portion of the beam, first and second connecting struts each connected through pivot bearings to the other end of a respective main beam member and to a respective end of an equalising member which is secured intermediate its ends to the middle axle, the middle axle being connected to the vehicle through a radius arm which allows the middle axle to move in an arc of a circle around the connection between the radius arm and the vehicle, each of the main beam members being adapted to be pivotally connected intermediate its ends to the vehicle, and the equalising member being secured to the middle axle through a resilient mounting for absorbing twisting stresses between the equalising member and the middle axle.

12. A suspension system according to Claim 11, wherein the resilient mounting of the equalising member to the middle axle is in the form of a bushing at a pivotal connection between the equalising member and a stool which is secured to the axle.

13. A suspension system according to Claim 12, wherein the bushing is of resilient material.

14. A suspension system according to Claim 11, substantially as hereinbefore described with reference to and as shown in Figures 1 to 4 of the accompanying drawings.

15. A suspension system according to Claim 11, substantially as hereinbefore described with reference to Figure 5 of the accompanying drawings.

16. A vehicle having a suspension system according to any one of Claims 1 to 10.

17, A vehicle having a suspension system according to any one of Claims 11 to 15.