Multi-axle vehicle suspension system

FIELD OF THE INVENTION

The present invention relates to a multi-axle vehicle suspension for a truck or trailer which provides for an even distribution of the vehicle load across the axles. BACKGROUND OF THE INVENTION

In vehicle suspension systems for large trucks and trailers, for example those used in multi-combination vehicles or road trains for the mining industry, it is common to mount a number of axles to the trailers) to support the vehicle load. One commonly employed suspension system 10 is shown in Figure 1 which includes three axles 12 supported by a combination of leaf springs 14. In this prior known vehicle axle suspension, there is a front hanger 16, two equaliser hangers 18 and 20, and a rear hanger 22, with axles 12 and spring assemblies 14 being fitted and connected to the hangers by way of the spring hooked sections being fitted to the equalisers and also through torque arms or rods 24.

When for example the front wheels encounter a condition in the road producing a vertical movement of the front axle, the resultant deflection in the front springs is transmitted in part by the equaliser to the rear springs. This results in an equalising effect in which any vertical displacement of either axle is distributed between the springs which minimises the weight differential between the axles.

A problem with these types of multi-axle load equalising suspension systems is that the load equalisation from one axle to another can be inadequate and abrupt. As one end of the equaliser rotates upwardly at the point at which the spring end contacts the leaf spring, the other end abruptly rotates downward. This action causes abrupt and unequal moments about the centre pivot point of the equaliser. Furthermore, such steel spring systems transmit lateral loads to the leaf spring to control lateral stiffness of the suspension, which places additional loads on the leaf springs.

The end results of improper load equalisation are numerous. If the axle which encounters bumps and overloads is unpowered, a loss of traction can occur on the powered axle. The suspension components, and springs in particular, are subjected to higher stresses and therefore their service life is shortened appreciably. As the leaf springs are subjected to overload they progressively lose capacity to absorb energy and therefore transmit more energy through the mounting brackets to the vehicle frame in some cases causing damage to the frame. Furthermore, wherever an unequal load distribution occurs within a suspension involving two or more axles, the axle which is overloaded transmits its load to the roadway in a manner that can be detrimental to the roadway. In summary, commonly used leaf-spring type suspensions and associated equalisation systems have a number of inherent problems, which most notably results in the need for regular maintenance, parts replacement and increased costs.

It is therefore an object of the present invention to overcome the aforementioned problems, or at least provide the public with a useful alternative.

SUMMARY OF THE INVENTION

Therefore in one form of the invention there is proposed A suspension system for a vehicle chassis comprising:

a platform assembly having associated therewith a support means for supporting at least one end of a wheel axle, said assembly further including an upper platform surface;

a hanger adapted to be fixed in a suspended configuration from said vehicle chassis, said hanger including a portion that is aligned vertically with a portion of said upper platform surface; and

a spring means located between the vertically aligned platform and hanger portions.

The use of an elastomer spring between the platform which supports the axle and the hanger associated with the vehicle frame ensures that the vehicle load is absorbed through the elastomer spring.

Preferably said vehicle chassis includes a longitudinal axis, and said platform assembly and hanger are connected via a longitudinal torque rod pivotably connected at both ends to said respective platform assembly and hanger.

In preference said suspension includes a second platform assembly and a second hanger at an opposed end of said wheel axle.

In preference said suspension includes a central vehicle frame mount disposed forwards of each of said platform assemblies, said central frame mount adapted to be fixed in a suspended configuration from said vehicle chassis, said first and second platform assemblies being connected by two pivolable transverse torque rods which extend forwardly and inwardly from each platform assembly to meet at said central frame mount.

Preferably said transverse torque rods are pivotably connected to said central frame mount and respective platform assemblies.

Preferably the spring means is an elastomer spring.

In preference each platform assembly is such that that each elastomer spring supported there above is disposed forwards and or rearwards of each axle. Preferably said elastomer spring is in the form of a cylindrical cushion manufactured from natural rubber, urethane, micro-cellular urethane or other suitable elastomeric material.

In preference each hanger assembly includes a suspended hollow housing for receiving said elastomer spring therein and compressing said spring by weight of the vehicle load. Preferably said vehicle is a multi-axle trailer adapted to support a trailer bin.

In a further form of the invention there is proposed a supension system for a vehicle including a front and a rear axle each having an opposed platform assembly and hanger coupled via transverse torque rods as defined above.

Preferably said front hanger is fixed and said rear hanger is an equalising hanger including an equaliser bar that is rockable about a pivot point, said equaliser bar extending longitudinally such that a portion thereof is vertically aligned with each of said front and rear platform assemblies for locating two elastomeric springs there between.

In preference said rear hanger includes a further fixed hanger disposed rearwardly thereof and including a portion that is vertically aligned with said rear platform for locating an elastomeric spring there between. In a still further form of the invention there is proposed a double axle vehicle including a vehicle chassis and a suspension system as defined above.

In an alternate form of the invention there is proposed a suspension system for a vehicle including a front axle, one or more middle axles, and a rear axle each having an opposed platform assembly and hanger coupled via transverse torque rods as defined above. Preferably said front hanger is fixed, said one or more middle hangers are equalising hangers each including an equaliser bar that is rockable about a pivot point, said equaliser bar extending longitudinally such that a portion thereof is vertically aligned with each of said front and middle platforms for locating two elastomeric springs there between.

In preference said rear hanger is an equalising hanger including an equaliser bar that is rockable about a pivot point, said equaliser bar extending longitudinally such that a portion thereof is vertically aligned with each of said middle and rear platforms for locating two elastomeric springs there between.

In preference said rear hanger includes a further fixed hanger disposed rearwardly thereof and including a portion that is vertically aligned with said rear platform for locating an elastomeric spring there between. In a further form of the invention there is proposed a vehicle including three or more wheel axles including a vehicle chassis and a suspension system as defined above.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations of the invention and, together with the description, serve to explain advantages and principles of the invention. In the drawings:

Figure 1 depicts a prior art leaf spring suspension system for a multi-axle trailer;

Figure 2 depicts a top perspective view of a multi-axle suspension system in accordance with the present invention;

Figure 3 depicts the top perspective view of Figure 2 with axles removed;

Figure 4 depicts a right hand side view of the suspension system of Figure 2;

Figure 5 depicts an underside view of the suspension system of Figure 2;

Figure 6 depicts a top view of the suspension system of Figure 2;

Figure 7 depicts a front end view of the suspension system of Figure 2;

Figure 8 depicts a left hand side view of the suspension system of Figure 2; and

Figure 9 depicts a rear end view of the suspension system of Figure 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. Wherever possible, the same reference numbers will be used throughout the embodiments and the following description to refer to the same and like parts.

The present invention relates to a multi-axle vehicle suspension system 30 for particular use in association with a trailer (not shown) to provide for even distribution of vehicle load across the axles. What is proposed is a non-torque reactive drive axle suspension system 30 adapted to equalise vertical and lateral loads through use of elastomer springs. It is to be understood that whilst the embodiment shown involves a trailer having three axles, the present invention could be equally useful in association with any other vehicle having two or greater than three axles.

Turning to Figures 2-9 there is shown a suspension system 30 above which is adapted to sit the chassis of a trailer bin (not shown). The suspension system 30 includes a number of mounts adapted to engage the trailer bin chassis (not shown) including three torque rod mounts 32 disposed along the central longitudinal axis of the suspension 30, mounts 34 associated with each of the eight hanger assemblies 36 forming part of the suspension system 30, and the six axle strap mounts 38 associated with each rebound tension strap 40 which are described in more detail below. The bin chassis (not shown) includes a plurality of receiving portions shaped and positioned to receive each of these mounts. The way in which the mounts engage with the bin chassis to secure the bin is considered known in the art and is not shown or described in further detail herein.

It is to be understood that the chassis being supported need not necessarily be that of a bin but any odier structure that may require support above a multi-axle suspension system.

In the embodiment shown, the suspension system 30 has associated therewith three spaced apart wheel axles 44. Again, the various components forming part of each axle and associated braking system will not be described herein for the purpose of brevity.

Figure 3 shows quite clearly that this embodiment utilises overslung bracket assemblies 46 to support the axles 44, however, underslung axles could equally well be used. The axles 44 are removed from the system depicted in Figure 3 to more clearly show how they are supported. Also removed from Figure 3 are the six axle platforms 48 located at opposed axle ends, from which the overslung axle bracket assemblies 46 are suspended. Each platform 48 includes a flat upper elongate surface which extends parallel with the suspension longitudinal axis, and at the centre of which is mounted a transverse torque rod support member 50 for pivotably supporting a transverse torque rod 52. There are thus three pairs of opposed, parallel platforms 48 along the length of the suspension and disposed between each platform 48, and at ends thereof, are the hanger assemblies 36.

Turning now to how the platforms 48, hanger assemblies 36 and the load chassis (not shown) interact, the system 30 employs a 4-bar (4 pivot points) linkage system per axle on each side of the suspension. In particular, each axle platform 48 is pivotably connected at its front side to a forwardly disposed hanger assembly 36 via a longitudinal torque rod 54. This longitudinal torque rod 54 defines two pivot points 56 and 58 of the linkage system. Similarly, each platform 48 is pivotably connected to a corresponding forwardly and inwardly disposed torque rod mount 32 via a transverse torque rod 52. This transverse torque rod 52 defines the second pair of pivot points 60 and 62 in the 4-bar linkage. The pivot points are most clearly viewable in the side view of Figure 4. Each of the hanger assemblies 36 includes at least one suspended cylindrical, hollow housing 64 which is open at the bottom and adapted to receive therein and compress by weight of the load an elastomer spring or, as per the embodiment shown, a cylindrical rubber cushion 66. The cushion 66 sits above either a front or rear end of each axle platform 48. The two inner hanger assembly pairs are equaliser hangers and each includes an equaliser beam 68 pivotable about a transverse pin 70 extending through the centre of the hanger. The beam 68 includes a cylindrical housing 64 suspended from a front and rear end thereof which aligns vertically with either a front or rear end of an adjacent axle platform such that an elastomer cushion 48 is supported therebetween.

The housing 64 is dimensioned such that even after the rubber cushion held therein is compressed, the housing will not contact the platform 48 there beneath. Instead, the cushion 66 will always extend a distance below the open bottom of the housing to absorb the load, as shown most clearly in the side view of Figure 4. Thus, the vertical load effectively rides on a full cushion of elastomeric material. The front and rear hanger assemblies 36 also include elastomer cushion housings 64 suspended therefrom, but these do not include equaliser beams and so are fixed rather than being pivotable. Figure 4 shows the housing associated with the front axle removed so that the reader can appreciate the extent to which the rubber cushion 66 is compressed.

The skilled addressee should now appreciate how the suspension 30 of the present invention is able to equalise load across all axles. Say the front axle encounters a condition in the road producing a vertical movement of the axle, the resultant deflection of the cushions associated with that axle is transmitted in part by the front opposed equaliser beams 68 to the cushions 66 associated with the rearward axles. The longitudinal torque rods 54 provide the required control in the longitudinal plane whilst the transverse torque rods provide control in the lateral plane.

The six rebound tension straps 40 mentioned earlier essentially prevent the suspension from falling apart by providing a direct connection between the load chassis (not shown) and each of the axle platforms 48. The straps 40 are also pivotably mounted to the platforms 48.

The suspension 30 is thus a compression suspension system, although there may be some occasions for example when the trailer is side tipping that the suspension will work in tension.

It has been found that use of the suspension system 30 of the present invention has a number of advantages over existing systems known to the Applicant, including but not limited to the following:

The suspension system has been found to be resistant to "wind up" during braking; • It is estimated that the load capacity on each axle using the suspension system of the present invention amounts to some 45 ton/axle, compared to around 25 ton axle using a leaf spring suspension as per the prior art system shown in Figure 1 ;

• Whilst more expensive to manufacture than leaf spring-type suspensions, the elastomer

suspension system of the present invention requires next to no ongoing maintenance and so the long term cost savings are significant. Leaf spring-type suspensions are typically maintained on a monthly basis are prone to leaf breakage; and

• The cost to manufacture the elastomer suspension system of the present invention is half the price of manufacturing a typical hydraulic suspension for use in the same application. Modification and variations to this particular embodiment will be obvious or apparent to those skilled in the art. Those modifications or variations are seen to be within the scope of this invention.

Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

In any claims that follow and in the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", i.e. the features specified may be associated with further features in various embodiments of the invention.