GB2099380A - Improvements in or relating to vehicle suspension devices - Google Patents

Abstract

A vehicle suspension comprises two rigid parts 110, 116 in sliding engagement with interposed hollow rubber springs 122. Removable pins 123 limit the relative up and down movement. Additional spring 140 of different characteristic may be provided. Bosses 98, 99 may locate ends of the springs 122. An arrangement for a tandem axle is described. The axle may be rigid or driven. <IMAGE>

Description

SPECIFICATION Improvements in or relating to vehicle suspension devices This invention relates to vehicle suspension devices, and to vehicles incorporating such devices. The term vehicle is not limited to self-propelled vehicles and includes trailers, for example agricultural trailers.

According to this invention a suspension device for a vehicle comprises first and second parts arranged in use for relative up and down movement, and elastomeric spring means between the first and second parts, relative lateral movement between the first and second parts being resisted by engagement of these parts.

In one arrangement the first part is in sliding engagement with the second part. Preferably the first part can slide within the second part.

At least one of the first and second parts may have a projection for locating an end portion of the spring means.

The spring means may comprises a plurality of rubber springs. The spring means may comprise softer spring means and harder spring means.

Removable means may be provided for limiting the relative up and down movement between the first and second parts; said means may comprise removable pins.

The second part may be a box-section, the pins extending between opposed sides of the box-section and engageable by end portions of the first part.

The second part may have a top wall, opposed side walls and end walls. The side walls may have opposed cut-outs which slidably receive a crossmember of the first part, the spring means being located on both sides of the cross-member.

The device may comprise two such devices pivotally connected and respectively for mounting on the axles of a tandem axle.

A suspension for a tandem axle may comprise a second part, and two, spaced, said first parts cooperable with said second part for respectively operatively cooperating with the two axles.

The invention also includes a vehicle having such a suspension device.

In the case of a vehicle with a tandem axle, there may be means for raising one axle to lift the associated wheels.

The invention also includes a kit of parts comprising rubber springs, and first and second parts, for assembly into such a device.

The invention may be performed in various ways and some specific embodiments with possible mod ifications will now be described by way of example with reference to the accompanying drawings in which Figure 1 is an exploded perspective view of a suspension device; Figure 2 shows the device of Figure 1 installed in a trailer; Figure 3 is a vertical central section through a rubber spring; Figure 4 is a modified arrangement; Figure 5 is a view of an arrangement similar to Figure 4; and Figure 6 is a view of part of Figure 5 with part cut away.

Springs have long been a problem in off-highway vehicular suspension design because of the heavy loads and great variation between empty vehicle weight and loaded vehicle weight. Constant rate leaf springs must be designed with a high rate to handle maximum loads. This type of suspension, therefore, at empty load or less than full load, provides very little shock protection for the vehicle or comfort to the driver. Other types of heavy duty off-highway equipment springs, such as hydro-pneumatic, viscoelastic, and stacked pads, either consist of many moving parts, require continuous lubrication, require constant surveillance of high pressure fluids, have high pressure seals on moving parts, or are a combination of these elements, and all are subject to maintenance problems. Maintenance problems means substantial maintenance costs and reduced machine availability.

The vehicle suspension system illustrated may be used in trailers and self-propelled vehicles, for example bulk high-sided tippers, for example for grain, sugar beet or sand; drop-sided flat decks for heavy palletised materials, for example fertiliser, cement and bricks; long-body trailers for bulky baled materials, for example hay and straw; low loaders for heavy plant and machinery, for example crawlers and tractors.

The unit can accommodate a range of rubber cord bias, shape and size options and can be tailored to suit various load/suspensions specification, within a single size box.

The suspension system is shown in an agricultural trailer. The system comprises an upper box part 110 having aflattopwall 111,, flat side walls 112,113 each having a rectangular cut-out 114, and flat end walls 115. The part 110 is made from sheet steei pieces welded together.

The underface 111a of the top wall 111 is provided with two spaced circular-section bosses 99. The lower box part 116 is similarly of welded steel pieces and comprises a top having parts 117, 118 with depending walls 117a,118a; and top cross part 119 beneath the top and between walls 117a,118a having depending side walls 119a, and end walls 1 19a each providing concavely curved edge 120.

Upstanding from the upper surface of walls 117,118 are circular-section projections 98 confronting respective bosses 99. An aperture extends through each boss 98 and the top of part 116 for flow of air.

An aperture extends through each boss 99 and top wall 111 for flow of air.

The outer surfaces of walls 117a and 118a are a close sliding fit with the inner surfaces of walls 112, 113. Two rubber suspension pads 122 are respectively received on the projections 98 and 99. Each pad 122 is hollow and is better seen in Figure 3. Each pad 122 has a central passage which widens in the middle. The outer surface has outwardly extending end sections 122a, 122b and has an axial intermediate section 1 22c. The end surfaces 22d are flat. The end portions 122e, 122fin use are closely but removably received on bosses 98, 99 respectively. A typical pad is AEON rubber spring type 1525 made by Firestone Tyre and Rubber Co. Limited of Manchester, England. Otherforms and shapes of pad are possible.For example pads incorporating cord or fabric layers in their outer regions, for example those sold underthe name Marsh Mellow (trademark) by Firestone Tyre and Rubber Co. Limited.

The pads 122 are placed under initial axial compression and strong pins or bars 123 are placed through apertures 124 in walls 113, 114 and engage the underfaces of the marginal end regions 1 17c, 1 18e of walls 117, 118 to hold the assembly together.

Split pins (not shown) extend through diametral apertures in the end regions of bars 123 and engage the outer surfaces of walls 112, 113 to prevent axial movement of the bars 123.

It will be noted that the outer peripheries of the pads 122 are spaced from the inner surfaces of walls 112, 113 and 115. In use, generally speaking, they are intended to remain free of contact from these surfaces, but it will be understood that if the vehicle goes over a particularly large bump or a particularly deep pot-hole the pads 122 may briefly engage one or more of these surfaces.

Grease nipples 125 are provided for lubricating the sliding side surfaces of parts 110 and 116.

In use, for example as shown in a trailer of Figure 2, the top wall 111 is welded to a chassis girder 130 and the curved surfaces 120, and possibly also edges 131 of walls 11 9a, are welded to the axle casing 134 of wheel 132. Relative up and down sliding movement between parts 110, 116 is cushioned by rubber spring pads 122 to provide a resilient mounting for the wheel.

It will be understood that in some cases the suspension system could be located upside down from the position shown, and be located between an axle and a chassis girder beneath the axle.

Each axle is provided with two similar suspension systems.

Instead of being welded to the axle, the part 116 could be held by U-bolts extending through the cross-part 119 and secured around the axle.

The suspension unit can readily be inserted in an existing trailer which does not have a suspension and in which the axle is, for example, welded to the chassis, by separating these parts and interposing the suspension system and welding it in place.

It will be understood that relative sidways movement between the parts 110, 116 which might cause the rubber springs 122 to shear, is effectively prevented by the interengagementofthe parts 110, 116.

The parts can readily be dissassembled and re-assembled if it provides necessary to replace a pad 122.

The suspension device provides good anti-roll characteristics for soft and rough ground with high or low loads.

The spring 122 may comprise a cylindrical hollow body of elastic material such as natural or synthetic rubber, or synthetic plastics, in which the hollow body is formed to provide intermediate its length a constriction in at least one transverse plane, said constriction counteracting the free expansibility in the plane thereof on loading of the spring in its longitudinal direction and, due to the consequential partial restriction of the inner hollow space above and below the constriction plane, transverse expansion planes having a small transverse expansion are formed, whereby a large maximum deflection of the spring is possible without lateral displacement, together with a continuously progressively increasing load-deflection characteristic line.

In a modification the section 110 is incorporated in a structural member of the chassis.

It will be understood that the sections 110,116 may receive pairs of rubber springs of different characteristics depending on the requirements of the vehicle.

Instead of being made from welded pieces, the sections could be formed by bending sheet metal.

In a modification shown in Figure 1 an additional softer central rubber pad 140 is provided for acting as the suspension at no load and this is longer than the two outer pads 122 which are of harder rubber and provide a harder suspension for the load. At no load, the outer pads are not operative; on adding load the centre pad compresses until the plate 111 engages the outer pads as the load increases.

In a further arrangement the outer pads are longer and softer and the central pad is harder. Other arrangements of pads are possible to give a desired suspension characteristic.

The plate 117 may have a dimension such as to have a small tolerance, for example 1/16 inch (0.16 cm), all round with respect to the inner surface of the walls 112,113,115.

The end faces of walls 112,113 may have laterally outwardly extended flat additions for engaging the outerfaces of sides 119ato act as an anti-torque device during braking of the vehicle.

The walls 11 9a can be replaced by a square section device for use with a square section axle.

Bushes 99 and/or 98 cam be omitted.

In the case where the device is to be used with a dual or tandem axle, see Figure 4, two devices as in Figure 2 are respectively connected to the axles 134 by rigid members 141, 142 welded to respective plates 111 which are pivoted on transverse pivot 143 connected to bracket 144fixed to chassis member 130.

In a modification the plates 111 of the two devices are extended and pivoted together and the separate members 141,142 are omitted.

With these arrangements the loads on the axles are substantially equalised, and in the case of an agricultural implement or vehicle the axles can accommodate irregular ground and can articulate relative to each other.

Figure 5,6 illustrate a preferred two-wheel suspension for a trailer tandem axle. The wheels are rotatably carried on the ends of square section rigid axles 150 and box-section members 151 are pivoted at 152 to chassis girders 130. The two members 151 form a swinging unit. The box part 153 similar to part 110 has side extensions 154 providing flat surfaces engaging surfaces 155 similar to 119a. This provides good resistance to turning of the axle on braking.

Three resilient rubber pads or springs are provided at each end of each member 151, the two outer ones being slightly longer and softer than the middle pad so that initial movement of part 155 relative to part 153 is cushioned by the outer pads The wheels may be provided with air-operated brakes, a valve for each wheel being located on the axle.

Each member 151 has one anti-torque device 154, 155, the anti-torque devices being at opposite corners of the unit.

It will be appreciated that in the rocking beam arrangement of Figures 5, 6 each pair of wheels is connected by a common axle and when one of these wheels moves up or down in relation to the other the rubber springs in addition to accommodating the vertical shock loads also accommodate lateral loads so that the axle and box parts 151, 153 are not unduly stressed; the axle in effect rotates about a fore and aft axis. Both axles can articulate, possibly independently and in opposite senses.

With this arrangement, therefore, it is possible to use instead in Figures 5, 6 a driven axle in a casing on which is mounted the unit 151 and a central differential would be used.

A hydraulic ram may extend between one of the axles and the chassis to raise as desired one pair of wheels from the ground to reduce tyre scrub in turning, tyre wear when unladen, and to increase axle loading and thus give improved traction on driven axles as desired on slippery ground. The ram is pressurized only when lifting so that normal operation of the suspension is not affected.

In a modification the section 116 is transverse to the vehicle and the wheels are rotatable on its ends and the springs allow rocking of section 116 as well as accommodating vertical loads.

Claims (15)

1. A suspension device for a vehicle comprising first and second parts arranged in use for relative up and down movement, and elastomeric spring means between the first and second parts, relative lateral movement between the first and second parts being resisted by engagement of these parts.

2. A suspension device as claimed in Claim 1, in which the firstpart is in sliding engagement with the second part.

3. A suspension device as claimed in Claim 2, which the first part can slide with the second part.

4. A suspension device as claimed in any preceding claim, in which at least one of the first and second parts has a projection for locating an end portion of the spring means.

5. A suspension device as claimed in any preceding claim, in which the spring means comprises a plurality of rubber springs.

6. Asuspension device as claimed in any preceding claim, in which the spring means comprises softer spring means and harder spring means.

7. Asuspension device as claimed in any preceding claim, comprising removable means for limiting the relative up and down movement.

8. A suspension device as claimed in Claim 7, in which the second part is of box-section, the removable means extending between opposed sides of the box-section and engageable by end portions of the first part.

9. A suspension device as claimed in any preceding claim, in which the second part has a top wall, opposed side walls and end walls, and the side walls have opposed cut-outs which slidably receive a cross-member of the first part, the spring means being located on both sides of the cross-member.

10. A suspension device comprising two suspension devices as claimed in any preceding claim, pivotally connected and respectively for mounting on the axles of a tandem axle.

11. A suspension device as claimed in Claim 1, for a tandem axle, comprising a said second part, and two, spaced, said first parts cooperable with said second part for respectively operatively cooperating with the two axles.

12. Asuspension device as claimed in Claim 11, including anti-torque means for cooperating with one axle.

13. A suspension device substantially as hereinbefore described with reference to and as shown in Figures 1 to 4, or Figures 5 and 6, of the accompanying drawings.

14. Avehicle having a suspension device as claimed in any preceding claim.

15. Avehicle as claimed in Claim 14 and Claim 11 having a tandem axle and two said suspension devices for said tandem axle, and means for raising one axle to lift associated wheels.