GB2508085A

GB2508085A - A trailer chassis suspension arrangement

Info

Publication number: GB2508085A
Application number: GB1317065.9A
Authority: GB
Inventors: Richard Larrington
Original assignee: Richard Larrington Ltd
Current assignee: Richard Larrington Ltd
Priority date: 2012-09-25
Filing date: 2013-09-26
Publication date: 2014-05-21
Also published as: GB201317065D0

Abstract

Apparatus comprising a trailer vehicle chassis 22 to which is mounted a plurality of suspension arrangements (2, figure 1), including a coiled compression spring 10. Preferably the trailer is an agricultural trailer which may also comprise hydraulic shock absorbers 12 and where the coiled compression spring may be located immediately above a wheel axle 24. The apparatus may also include a mechanical actuator 26, such as a hydraulic cylinder and piston arrangement, which is mounted on the underside of the chassis, and a mechanical stop 30 which is mounted on the wheel axle. The end of the piston 28 of the mechanical actuator and the mechanical stop should be of complimentary shapes so that when the piston is engaged with the mechanical stop it fits and can be used to level the trailer chassis. The lifting action of the chassis levels the suspension across a wheel axle and may be useful when the trailer is being used across a slope or uneven ground.

Description

TRAILER SUSPENSION ARRANGEMENT

This invention relates to a suspension arrangement for trailer vehicles.

Presently, a variety of suspension systems are available for trailers, such as leaf spring suspension, air suspension and hydraulic suspension. All these have a mechanical connection to the chassis and the carrying axles. Trailers can be used for a variety of purposes; for example, for domestic use, for transporting heavy and/or bulky materials, for transporting other vehicles, for transporting livestock or for other agricultural use.

Considering agricultural trailer vehicles in particular, they are being increasingly towed at relatively high speeds carrying relatively larger loads and this has caused greater oscillation of the body of the trailer, rolling on top of the vehicle chassis which can result in dangerous overturning of the vehicle.

There are disadvantages to all these suspension systems in that leaf springs are prone to breakage, air bags are prone to bursting, and hydraulic systems are prone to leakage of oil onto, for instance, road surfaces or food crops.

Suspension systems are also connected to the braking system of the vehicle. The ideal suspension system has maximum up and down axle body movement, but little to no side-to-side body roll. The suspension system is directly connected to the braking load sensing system and is used to increase or decrease pressure onto the brakes according to the load on top of the suspension system. The greater the axle movement up or down, the better the system can control braking pressure, which then controls the skidding and stopping of the tyres on the road surface.

Presently, single leaf suspension systems for trailers have good solid side-to-side stiffness but have little variation in up and down axle body movement. Conversely, multi-leaf spring suspension systems have good variation in up and down axle body movement, but allow too much body roll, which could result in a vehicle overturning on slopes. Air suspension systems have excellent suspension characteristics, but they are relatively expensive and when in use on agricultural trailers, the nature of the environment in which they operate results in a risk that the exposed air bags, usually made of a rubber material, can burst. Hydraulic suspension systems are complicated and expensive; whilst they have good stiffness, they can be slow to respond to braking when the oil in the pistons is cold. In addition, if the hydraulic pistons leak, the result is oil on the road surface or contamination of food crops.

Overall, suspension systems of trailers are either leaf sprung or use an air suspension arrangement which can be connected to a compressed air supply of the towing vehicle for convenience.

According to the present invention, there is provided apparatus comprising a trailer vehicle chassis having an upper surface and an under surface to which is mounted a plurality of suspension arrangements, wherein each suspension arrangement includes a coiled compression spring.

Owing to this aspect, trailer vehicles can be supplied with cost effective reliable coiled spring suspension arrangements.

Agricultural trailers have, generally speaking, either leaf sprung suspension or air bag suspension systems and have not been provided before with coiled compression spring suspension systems, which offer advantageous characteristics is for the trailer in terms of performance requirements.

Advantageously, each of the suspension arrangements further comprises a mechanical actuator mounted between the under surface of the agricultural vehicle chassis and a mechanical stop. Preferably, the mechanical actuator is a hydraulic cylinder and piston arrangement and the mechanical stop is mounted upon an axle of the agricultural vehicle.

In order that the present invention be clearly and completely disclosed, reference will now be made, by way of example only, to the accompanying drawings, in which:-Figure 1 is a perspective view of a pair of agricultural suspension arrangements; Figures 2a-2d show various elevational views of an agricultural vehicle chassis frame with a plurality of the suspension arrangements of Figure 1; Figure 3 shows a perspective view from beneath of the chassis of the agricultural vehicle of Figure 2, but of a preferred version of the suspension arrangements; Figure 4 is a side view of the preferred version of Figure 3, with a piston rod of an hydraulic piston device in a raised position; Figure 5 is a view similar to Figure 4, but with the piston rod in a lowered position; and Figure 6 is a perspective view of another preferred version of the suspension arrangements.

Referring to Figure 1, a suspension arrangement 2 comprises a mounting bracket 4 at one end thereof for mounting the arrangement 2 to an agricultural vehicle chassis (see Figures 2a to 2d), an arm piece 6 pivotally mounted to the bracket 4 by way of a bolt 8, and a coiled compression spring 10 connected to an end region of the arm piece 6 at the opposite end of the arrangement 2 to the bracket 4. The coiled spring 10 has upper and lower bushings 10' and 10" respectively, the upper bushing 10' being attached to an under surface of an agricultural vehicle chassis and the lower bushing 10" being attached to the end region of the arm piece 6. Each suspension arrangement includes a shock absorbing device 12 in the form of hydraulic shock absorbers mounted between the bracket 4 and a wheel axle received in an inverted is substantially U-shaped channel 14 formed by a channel member 16 attached to the bottom surface of the arm 6 at the end region of the arm piece 6 proximal to the coiled spring 10.

On the top surface of the arm 6 substantially immediately above the channel member 16 there is attached thereto a pad or plate 18 upon which a movement limitation device 20 may bear during use. The limitation device 20 is substantially T-shaped in cross-section with the upper planar surface 20' being connectible to the underside of the agricultural vehicle chassis and a cylindrical element 20" extending downwardly from the planar surface 20'. During use, the limitation device 20 prevents over compression of the coiled spring 6 by limiting the substantially vertical movement of the arm piece 6 about an axis of the bolt 8.

Referring to Figures 2a to 2d, the suspension arrangements 2 are shown attached to an agricultural vehicle chassis 22 having an upper surface 22' and an under surface 22". The chassis 22 may be in the form of, as shown, a vehicle that is an agricultural trailer to be towed or pushed along by a separate vehicle. However, the chassis 22 could be in the form of a single vehicle which does not require to be towed or pushed along. Figures 2a to 2d also show a wheel axle 24 received into the channel 14 and the cylindrical portion 2" of the movement limitation device 20 attached to the underside of the chassis 22.

Referring to Figures 3 to 5, a preferred version of the suspension arrangements 2 further comprises a mechanical actuator 26 in the form of a piston and cylinder s device, for example, a hydraulic piston and cylinder device, the upper portion of which is attached, substantially directly above the axle 24, to the chassis 22. A lower end of the rod has attached thereto an abutment 28 and the wheel axle 24 has attached to it a mechanical stop 30 which is of a complimentary shape to the abutment 28. The shape shown is substantially triangular in cross-section, but could, of course, be of any complimentary form.

The piston and cylinder devices 26 are enable the agricultural vehicle to be levelled when operating on sloped ground surfaces when the abutment 28 is engaged with the complimentary shape of the mechanical stop 30. Figure 4 shows the abutment 28 in a first raised position, there being a gap between the abutment 28 and the is mechanical stop 30, whereas Figure 5 shows the abutment 28 in a second lowered position in which the abutment is engaged with the mechanical stop 30 in which force applied against the mechanical stop 30 causes a lifting action on the chassis 22.

Referring to Figure 6, the pair of suspension arrangements 2 are substantially the same as the pair shown in Figure 1 except that the coiled compression spring 10 in its bushings 10' and 10" is located immediately above the channel member 16 and thus an axle 32. Each suspension arrangement 2 is secured to the axle 32 by away of a plurality of U-shaped bolts 34, the free ends of which projects through a plate between the channel member 16 and the lower bushing 10".

The coiled spring is, preferably made of steel which is around 40mm in diameter. As an alternative arrangement, two coiled springs arranged co-axially, one inside the other could be used and each be of roughly 20mm diameter, which could reduce the cost of the coiled spring arrangement.

The coiled spring 10 acts just like presently used air bags of an air suspension system in that they show good side-to-side stiffness and also good up and down oscillation, but without the disadvantages of an air suspension system discussed above. Furthermore, in an agricultural situation, a compressed air supply might not be available on towing tractors. The conditions that agricultural trailers are used in means that stones, dirt and other debris can easily cause problems to the air bags in particular. Coiled spring suspension systems thus offer trailer vehicles with simple effective suspension, excellent smoothness of ride without any significant body roll and good braking at relatively low cost.

Claims

CLAIMS1. Apparatus comprising a trailer vehicle chassis having an upper surface and an under surface to which is mounted a plurality of suspension arrangements, wherein each suspension arrangement includes a coiled compression spring.
2. Apparatus according to claim 1, wherein said trailer vehicle chassis is an agricultural trailer vehicle chassis.
3. Apparatus according to claim 1 or 2, wherein each of the suspension arrangements further comprise a mechanical actuator mounted between the under surface of the vehicle chassis and a mechanical stop.
4. Apparatus according to claim 3, wherein the mechanical actuator is a hydraulic cylinder and piston arrangement and the mechanical stop is mounted upon a wheel axle of the vehicle.
5. Apparatus according to any preceding claim, wherein each suspension arrangement includes a shock absorbing device.
6. Apparatus according to claim 5, wherein the shock absorbing device is a hydraulic shock absorber.
7. Apparatus according to claim 5 or 6, wherein the shock absorbing device is mounted between a bracket of the suspension arrangement and the wheel axle.
8. Apparatus according to any preceding claim, wherein the suspension arrangements are mounted so that the coiled compression spring is located immediately above a wheel axle.
9. Apparatus substantially as hereinbefore described with reference to Figures 1 and 2.
10. Apparatus substantially as hereinbefore described with reference to Figures 3 tos.
11. Apparatus substantially as hereinbefore described with reference to Figure 6.