Tandem AXLE suspension assembly

Abstract

A tandem axle suspension assembly is disclosed, comprising a base configured to engage a chassis of a vehicle, and first and second suspension arms rotatably connected to the base about a common rotational axis. Each suspension arm includes a first end and a second end, with the rotatable connection positioned between the ends. The first end of the first suspension arm is located on an opposite side of the rotational axis from the first end of the second suspension arm. Each suspension arm includes axle engaging means at its first end and biasing means at its second end, the biasing means being positioned between the suspension arms and configured to bias them away from each other. Shock absorbing means are provided between each suspension arm and the base. A trailer comprising a pair of the tandem axle suspension assemblies is also disclosed.

Description

[0001] TANDEM AXLE SUSPENSION ASSEMBLY

[0002] 1. FIELD OF THE TECH NOLOGY

[0003] The present invention relates to a suspension system for a tandem axle vehicle, in particular, but not exclusively, a trailer.

[0004] 2. BACKGROUND TO THE TECHNOLOGY

[0005] Many heavy vehicles use groups of two or even three axles in order to reduce the load on any one of the axles.

[0006] Often, the suspension system to which the axles are mounted make some provision to "share" the load between the axles, so that no one axle carries the entire load which is intended to be distributed among all the axles in the group.

[0007] A common load sharing arrangement is a so-called "walking beam". In this arrangement, two axles are mounted to a pair of longitudinal beam members, one provided on each side of the vehicle. Each beam is connected to the vehicle chassis by a central pivotal connection, and the axles are mounted to the ends of the beam. When one of the axles is loaded more than the other, the beams pivot to increase the load on the lightly loaded axle.

[0008] In some prior art examples, the beam members may comprise leaf springs. In other examples, springing is provided between the pivot and the vehicle chassis. In still further examples, a springing element is provided between each axle and the beam.

[0009] A weakness of designs which rely on leaf springs is that these may provide a harsh ride, particularly at light loads. Some other tandem axle suspension systems may be overly complicated, and may have an excessive number of rotating joints, which can wear, leading to degraded suspension performance.

[0010] The term "vehicle" is used herein to refer to both powered vehicles (e.g. trucks) and to non-powered vehicles (e.g. trailers). 3. OBJECT OF THE TECHNOLOGY

[0011] It is an object of the technology to provide a tandem axle suspension assembly which is not reliant on leaf springs, and which has relatively few rotating connections. Alternatively, it is an object of the technology to provide a tandem axle suspension which overcomes or ameliorates problems with such suspensions at present.

[0012] Alternatively, it is an object of the technology to at least provide the public with a useful choice.

[0013] 4. SUMMARY OF THE TECHNOLOGY

[0014] According to one aspect of the technology there is provided a tandem axle suspension assembly comprising: a base for engaging a chassis of a vehicle, first and second suspension arms rotatably connected to the base, the first and second suspension arms configured to rotate about a common rotational axis, each suspension arm having a first end and a second end and the rotatable connection being between the first and second end of each suspension arm, wherein the first end of the first suspension arm is on an opposite side of the rotational axis to the first end of the second suspension arm, each suspension arm having axle engaging means at the first end of the arm and biasing means at the second end of the arm, the biasing means provided between each suspension arm and the other suspension arm and configured to bias each suspension arm away from the other suspension arm, and wherein shock absorbing means are provided between each suspension arm and the base.

[0015] Preferably, the first and second suspension arms are in a scissors configuration.

[0016] Preferably, the second suspension arm has an opening between the first and second ends, and the first suspension arm extends through the opening.

[0017] Preferably, each suspension arm has an opening between the first and second ends through which the shock absorbing means provided to the other suspension arm extends, and wherein the first suspension arm extends through the opening in the second suspension arm. Preferably, the base comprises a substantially rectangular main portion and two side portions extending downward from opposite sides of the main portion to form an inverted U shape, and the suspension arms are rotatably connected to the side portions by a pivot.

[0018] Preferably, the side portions are substantially triangular, and the pivot is connected to the side portions near an axis of the triangle.

[0019] Preferably, the base includes at least one mounting portion comprising a pair of brackets extending upward from the main portion.

[0020] Preferably, a first of the brackets extends longitudinally along the base and a second of the brackets extends transversely to the longitudinal axis of the base.

[0021] Preferably, each suspension arm is substantially rigid between its first and second ends.

[0022] Preferably, the axle engaging means comprises a plurality of U-bolts.

[0023] Preferably, the spacing between inner and outer U-bolts is at least 150 mm.

[0024] Preferably, the biasing means comprises a rubber block positioned between the second end of one suspension arm and the first end of the other suspension arm.

[0025] According to another aspect of the technology there is provided a trailer comprising a frame, a tandem axle suspension assembly of the first aspect provided to a first side of the frame and a second side of the frame, a first axle connected to the axle engaging means of the first suspension arms of each tandem axle suspension assembly, a second axle connected to the axle engaging means of the second suspension arms of each tandem axle suspension assembly, wherein each axle is provided with at least one wheel at each end of the axle.

[0026] Further aspects of the technology, which should be considered in all its novel aspects, will become apparent to those skilled in the art upon reading of the following description which provides at least one example of a practical application of the technology. 5. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] One or more embodiments of the technology will be described below by way of example only, and without intending to be limiting, with reference to the following drawings, in which:

[0028] Figure 1 is a perspective view of a tandem axle suspension assembly according to one form of the technology.

[0029] Figure 2 is a front view of the suspension assembly of Figure 1 .

[0030] Figure 3 is a top view of the suspension assembly of Figure 1 .

[0031] Figure 4 is a cross-section view through plane A-A.

[0032] Figure 5 is a cross-section view through plane B-B.

[0033] Figure 6 is a rear view of the suspension assembly of Figure 1 .

[0034] Figure 7 is a bottom view of the suspension assembly of Figure 1.

[0035] Figure 8 is a diagrammatic plan view of a trailer comprising two tandem axle assemblies of the present technology, with a bed of the trailer not shown for clarity.

[0036] Figure 9 is a perspective view of a tandem axle suspension assembly according to one form of the technology.

[0037] 6. BRIEF DESCRIPTION OF EXEMPLARY FORMS OF THE TECHNOLOGY

[0038] Referring to Figures 1 -7, a tandem axle suspension assembly according to one form of the technology is generally indicated by arrow 100.

[0039] The suspension assembly 100 comprises a base 1 for engaging a chassis of a vehicle (e.g. a trailer 200). In the example shown the base 1 comprises a substantially rectangular main portion 2 with two side portions 3 extending downward from the main portion 2, such that the main portion 2 has an inverted U shape in cross section (e.g. when viewed from one end). References herein to orientations such as "upward", "downward", "above", "below" and the like refer to the suspension assembly when in an in-use orientation.

[0040] The side portions 3 are provided to opposite sides of the main portion 2. In the example shown the side portions 3 are substantially triangular, although other configurations are possible.

[0041] The base 1 further comprises at least one mounting portion 4 for engaging the base 1 to the chassis. In the example shown, the at least one mounting portion 4 comprises a pair of brackets 5, 6, each bracket extending upward from the main portion 2. In the example shown a first bracket 5 extends longitudinally along the base 1, and a second bracket 6 extends transverse to the longitudinal axis of the base 1. Those skilled in the art will appreciate that the brackets 5, 6 shown are just one form of mounting portion 4, and suitable alternative means of mounting the base 1 to the vehicle chassis may be used. For example, in some forms of the technology the main portion 2 may be connected directly to the chassis by suitable fasteners.

[0042] The suspension assembly 100 comprises first and second suspension arms 10, 1 1 . The suspension arms 10, 11 are rotatably connected to the base 1, for example to the side portions 3. The suspension arms 10, 1 1 are connected to rotate around a common rotational axis.

[0043] The rotational connection 12 is between the first and second ends 13, 14 of each suspension arm 10, 1 1, preferably toward the middle of each suspension arm 10, 1 1, such that the first end 13 of the first suspension arm 10 is on the opposite side of the rotational connection 12 to the first end 13 of the second suspension arm 1 1 (that is, it is on the opposite side of a vertical plane which is coplanar with the rotational axis of the rotational connection 12). In examples, the suspension arms 10, 1 1 may form a "scissors" configuration. In one form of the technology, a pivot 15 (which may also be called an axle) extends between the side portions 3, for example adjacent the apex 16 of each side portion 3, and the suspension arms 10, 11 are rotatably connected to the pivot 15, for example via bearings. In the example shown, the first end 13 of each suspension arm 10, 1 1 is below the second end 14 of the other suspension arm 10, 11. In one form of the invention, each suspension arm comprises two substantially vertically orientated side members 20 and two substantially horizontally orientated end plates 21 connecting the side members 20 at the opposing ends of each suspension arm, as best seen in Figure 5. Each suspension arm 10 ,1 1 may therefore comprise an opening 22 between the side members 20 and end plates 21 , as best seen in Figures 1 and 4. In some examples the suspension arms 10, 1 1 may be configured such that one of the suspension arms (for example the first suspension arm 10) is slightly narrower than the other (e.g. the second suspension arm 1 1 ) and can extend through the opening 22 in the other suspension arm, between the side members 20. However, in other forms of the technology (not shown) the suspension arms 10, 11 may be side by side on the pivot 15. The suspension arms 10, 11 are substantially rigid between the first and second ends 13, 14.

[0044] Vehicle axle engaging means are provided at a first end 13 of each of the suspension arms 10, 11 . In the example shown, the vehicle axle engaging means comprise a plurality of 'U' bolts 23, but any other suitable other engaging means may be used. Preferably, the distance between the inner and outer U bolts may be at least 150 mm. This relatively large spacing may assist in bracing the axle, e.g. maintaining the orientation of the axle relative to the suspension arm it is attached to.

[0045] Spring or biasing means 24 may be provided between the second end 14 of each suspension arm and the first end 13 of each other suspension arm (e.g. between the second end 14 of the first suspension arm 10 in the first end 13 of the second suspension arm 1 1 ). In one form of the technology the spring or biasing means 24 comprise polymer (e.g. rubber) blocks, however traditional steel springs may also be used. This arrangement ensures that load is shared between the axles, since an unbalanced load on the first end of one of the suspension arms 10, 1 1 will force the first end of the other suspension arm 10, 11 downward, thereby increasing its share of the load.

[0046] Typically, shock absorbing means (for example telescopic hydraulic shock absorbers 25) are provided between each suspension arm 10, 11 and the base 1 . In examples, the shock absorbers 25 are mounted near the first end 13 of each suspension arm 10, 11 and extend through the openings 22 in the suspension arms 10, 11 to the base 1 . The shock absorbers 25 may be connected to the side members 20 of the suspension arms 10, 11 , adjacent the end plates 21 .

[0047] The main portion 2 of the base 1 may comprise two apertures 26 to allow the ends of the shock absorbers 25 to extend through the main portion 2. The main portion 2 may comprise shock absorber mounting brackets 27 provided to opposite sides of each aperture 26. In other examples the shock absorbers may be connected to brackets beneath the main portion 2 of the base 1 . In some forms of the technology rubber block / elastomer type shock absorbing means may be used rather than telescopic shock absorbers.

[0048] In one form of the technology, the suspension assembly 100 may be used with separate bump stops 30 (labelled in Fig, 1 ) which are attached directly to the vehicle chassis. In other examples, the lower surface of the base 1 may be provided with one or more resilient pads 31 (labelled in Fig. 2) which operate as bump stops.

[0049] Referring next to Figure 8, a trailer 200 is shown comprising a frame 201 , and a tandem axle suspension assembly 100 provided to the first side of the frame and the second side of the frame 201 . A first axle 202 is connected to the axle engaging means of the first suspension arms 10 of each tandem axle suspension assembly 100, and a second axle 203 is connected to the axle engaging means of the second suspension arms 11 of each tandem axle suspension assembly. At least one wheel 204 is provided at each end of each axle 202, 203.

[0050] Figure 9 shows a slightly different form of the tandem axle suspension assembly 100 according to the present technology. In the example shown in Figure 9, cutouts 28 are provided to the side members 20 of the suspension arms 10, 1 1 to assist in locating the axles 202, 203. U-bolts 23 (not shown in Figure 9) are used to connect the axles 202, 203 to the suspension arms 10, 11.

[0051] Those skilled in the art will appreciate that the present invention provides a load sharing suspension assembly which is compact, has a minimum of components and pivotal connections, but which still provides damping of all motion of the axles.

[0052] Other Remarks

[0053] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".

[0054] The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference. Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world.

[0055] The technology may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features. Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

[0056] It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the technology and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present technology.

Claims

Claims1 . A tandem axle suspension assembly comprising: a base for engaging a chassis of a vehicle, first and second suspension arms rotatably connected to the base, the first and second suspension arms configured to rotate about a common rotational axis, each suspension arm having a first end and a second end and the rotatable connection being between the first and second end of each suspension arm, wherein the first end of the first suspension arm is on an opposite side of the rotational axis to the first end of the second suspension arm, each suspension arm having axle engaging means at the first end of the arm and biasing means at the second end of the arm, the biasing means provided between each suspension arm and the other suspension arm and configured to bias each suspension arm away from the other suspension arm, and wherein shock absorbing means are provided between each suspension arm and the base.

2. The tandem axle suspension assembly of claim 1, wherein the first and second suspension arms are in a scissors configuration.

3. The tandem axle suspension assembly of claim 1 or 2, wherein the second suspension arm has an opening between the first and second ends, and the first suspension arm extends through the opening.

4. The tandem axle suspension assembly of any one of claims 1 to 3, wherein each suspension arm has an opening between the first and second ends through which the shock absorbing means provided to the other suspension arm extends.

5. The tandem axle suspension assembly of claim 4, wherein the first suspension arm extends through the opening in the second suspension arm.

6. The tandem axle suspension assembly of any one of claims 1 to 5, wherein the base comprises a substantially rectangular main portion and two side portions extending downward from opposite sides of the main portion to form an inverted U shape in cross section, wherein the suspension arms are rotatably connected to the side portions by a pivot which extends between the side portions.

7. The tandem axle suspension assembly of claim 6, wherein the side portions are substantially triangular and the pivot is connected to the side portions near an axis of the triangle.

8. The tandem axle suspension assembly of any one of claims 1 to 7, wherein the base comprises a pair of brackets extending upward from the main portion.

9. The tandem axle suspension assembly of claim 8, wherein a first of the brackets extends longitudinally along the base and a second of the brackets extends transversely to the longitudinal axis of the base.

10. The tandem axle suspension assembly of any one of claims 1 to 9, wherein each suspension arm is substantially rigid between its first and second ends.11 . The tandem axle suspension assembly of any one of claims 1 to 10, wherein the axle engaging means comprises a plurality of U-bolts.

12. The tandem axle suspension assembly of claim 1 1, wherein the spacing between inner and outer U-bolts is at least 150 mm.

13. The tandem axle suspension assembly of any one of claims 1 to 12, wherein the biasing means comprises a rubber block positioned between the second end of one suspension arm and the first end of the other suspension arm.

14. A trailer comprising a frame, a tandem axle suspension assembly according to any one of claims 1 to 13 provided to each of a first side of the frame and a second side of the frame, a first axle connected to the axle engaging means of the first suspension arms of each tandem axle suspension assembly, a second axle connected to the axle engaging means of the second suspension arms of each tandem axle suspension assembly, wherein each axle is provided with at least one wheel at each end thereof.

Images