GB2030088A - Vehicle suspension - Google Patents

Abstract

A vehicle suspension for tandem axles in which the axles (6, 8) are sprung on leaf springs (2, 4) the ends of the springs being connected to the vehicle by rocker plates (14-19) so that the springs can move up and down relative to the vehicle and each rocker plate is connected to each other by a pair of links (32, 34), the axles each being connected to the vehicle by a radius rod (48, 50). The use of a pair of links eliminates asymetric loads in the suspension which result in twisting forces and bearing failures. <IMAGE>

Description

SPECIFiCATION Vehicle suspension This invention relates to road vehicle suspension and in particular to axle suspension for trailers, semi-trailers and tractor vehicles of the type in which a pair of wheels at each side of the vehicle are connected in tandom in such a way that as one wheel of a pair is subjected to load a part of the load is transmitted by the suspension to the axle of the other wheel of the pair so that the load is shared between the axles. Such suspensions will hereafter be referred to as a 'tandem suspension'.

In our Patent No. 1 503142 such a suspension is described. In this patent a construction is described in which the connection between the pairs of wheels is by means of a single link. In some cases it has been found that the use of only a single link causes asymmetric loads on the suspensions with resultant considerable twisting forces and bearing failures.

An object of the present invention is therefore to even out the suspension loading and to provide an improved tandem suspension.

A road vehicle in accordance with this invention has a 'tandem suspension' each axle being connected to a leaf spring and each of the two axles at each side of the vehicle having pivotally mounted rocker plates each rocker plate being inter-connected with each spring and the rocker plates being so located and arranged that each end of each of the two axle leaf springs can move vertically up and down relatively to the vehicle, the rocker plates and each axle being connected to the vehicle by a pivotally mounted radius rod, for each end of each spring being pivotally connected by a pair of connecting links.

Preferably the rocker plates are mounted in pivotally aligned pairs on each side of the vehicle, one link being pivotally connected on one of each pair of rocker plates and the other link being pivotally connected to the other of each pair of rocker plates, the pivotal connection between links and rocker plates being axially aligned. The connection between rocker plates and springs is preferably by means of slipper pads.

In the embodiment described three pairs of rocker plates are provided on each side of the vehicle each central rocker plate of each three pairs acting to interact with adjacent ends of each spring. However, four pairs of rocker plates may be provided on each side of the vehicle with a pair of rocker plates provided on each end of the springs.

The invention will now be further described by way of example with reference to the accompanying drawings in which: Figure 1 is a side view of a tandem suspension in accordance with the invention, Figure 2 is a part cross-section of a central rocker plate and the suspension taken along the line A-A of Fig. 1, and Figure 3 is a part cross-section of an end rocker plate and the suspension taken along the line B-B of Fig. 1.

Referring to Figs. 1, 2 and 3 the suspension comprises at each side of the vehicle, leaf springs 2, 4 for the relatively forward and rearward axles 6, 8 of a pair which work in tandem to carry a load, the axles being connected to the leaf springs by conventional Ubolts 10.

Both ends of both leaf springs are engaged by slipper pads which are not shown but which are similar to those shown in our Patent No. 1 503 1 42 and these are carried by three pairs of rocker plates 14 and one not shown but designated 1 5 at the front of the front axle, 1 6 and 1 7 at the rear of the front axle and front of the rear axle (see Fig. 2) and 18, 1 9 at the rear of the rear axle (see Fig. 3), rocker plates 16, 1 7 acting for both axles.

Each pair of rocker plates 14, 15, 16, 17, and 18, 1 9 is connected together by a common tubular member 20 (not shown) 22 and 24 respectively by welding. Each tubular member of respective plates is pivotally mounted in hanger brackets 26, 28 and 30 respectively by means of quadrant pins 31, the brackets being mounted to the vehicle.

The rocker plates are interconnected by a pair of straight links 32 and 34 of U-shaped cross-section so that plates 15, 1 7 and 1 9 are connected by link 32 and plates 14, 16 and 1 8 are connected by link 34. The interconnection between the links and rocker plates is in each case by means of a tubular member 36 welded at each linking position to each link 32, 34, a resilient bush 38 preferably of rubber, a tie rod bush 40 pivotally mounted in the case of the central rocker plates 1 6 and 1 7 on a common rocker pin 42 and in the case of end rocker plates 14, 1 5 and 18, 1 9 on pin assemblies 44, pin 42 being pivotally mounted in a cylindrical member 46 welded at each end to plates 1 6 and 1 7 and pin assemblies 44 welded separately to plates 14, 15, 18 and 19. Thus plates 14, 15 and T9, 1 8 which are similar are axially aligned by the axes of members 24 and 44 and plates 16, 1 7 are axially aligned by the axes of members 22 and 46.

As the slipper pads (not shown) only rest on the ends of the springs the axles are not located longitudinally and hence radius rods 48 and 50 are provided. Each rod is pivotally attached to the central bracket 28 by bushings 52 and to U-bolt members 10.

In order to allow free pivotal movement of the rocker pin 42 and the bushing members 32, 38 and 40 in the bracket 28 an arcuate slot 52 is provided in bracket members 54 and 56 of bracket 28 (see Figs. 1 and 2).

Rocker plates 14, 1 5 and 18, 1 9 are each provided at their end extremities with spring drop out studs 58 on which are mounted spacer tubes (not shown). Similar provision is made on the extremities of the central rocker plates 16, 1 7 but are not shown.

The provision of rocker plates and links either side of each spring substantially increases the resistance of the assembled tandem suspension to asymmetric forces.

In order to lift one of the two axles during use of the vehicle which term includes trailers and semi trailers provision may be made in a similar way to that shown in our Patent No.

1503142.

Claims (4)

1. A road vehicle suspension for trailers, semi-trailers and tractor vehicles of the type in which a pair of wheels at each side of the vehicle are connected in tandem in such a way that as one wheel of a pair is subjected to a load a part of the load is transmitted by the suspension to the axle of the other wheel of the pair so that the load is shared between the axles wherein each axle is connected to a leaf spring and each of the two axles at each side of the vehicle is so located and arranged that each end of each of the axle leaf springs can move vertically up and down relative to the vehicle, the rocker plates and each axle being connected to the vehicle by a pivotally mounted radius rod, each rocker plate being pivotally connected to each other by a pair of connecting links.

2. A suspension as claimed in Claim 1 wherein the rocker plates are pivotally aligned in pairs on each side of the vehicle, one link being pivotally connected on one of each pair of rocker plates and the other link being pivotally connected to the other of each pair of rocker plates the pivotal connection between links and rocker plates being axially aligned.

3. A suspension as claimed in claims 1 or 2 wherein the connection between rocker plates and springs is by means of slipper pads.

4. A road vehicle suspension substantially as described with reference to the accompanying drawings.