GB2141677A

GB2141677A - Tapered leaf spring bus suspension

Info

Publication number: GB2141677A
Application number: GB08314057A
Authority: GB
Inventors: Bernard Ashton; James E Magleave; John H Abram
Original assignee: Leyland Vehicles Ltd
Current assignee: Leyland Vehicles Ltd
Priority date: 1983-05-20
Filing date: 1983-05-20
Publication date: 1985-01-03
Also published as: GB8314057D0

Abstract

A suspension for the axle (10) of a vehicle, especially useful where a low floor height is required, comprises a leaf spring; one end (13) of which is tapered and is joined rigidly to the vehicle body (12), and the other end (15) of which is of constant cross-sectional area and supports the vehicle body (12) through an air spring (16). <IMAGE>

Description

SPECIFICATION Tapered leaf spring bus suspension This invention relates to a suspension for a wheeled vehicle.

A low floor height is desirable in a vehicle, such as a city bus, to which access needs to be readily had from outside the vehicle.

The need for a low floor height can conflict with the use of previously known suspension which makes use of conventional springs which in a low floor arrangement would result in extensive intrusions through the floor and into the vehicle interior. A solution to the question of intrusion is to utilise air springs which can be made of relatively short length.

However sufficient length suspension travel can introduce further problems particularly if the vehicle has a wide range of load capacity.

A further requirement in the suspension is sufficient roll stiffness in order that the vehicle is well controlled in roll during cornering without the use of an anti roll bar.

A motor vehicle suspension is disclosed in UK Patent 1,350,057 in which an axle is located longitudinally of the vehicle by a pair of longitudinally extending arms; each arm comprises a spring steel leaf disposed in a substantially vertical plane; one end of each leaf is pivotably connected to the vehicle body structure and the leaf is fixed to the axle so that the twisting movement of the axle relative to the body structure is accommodated by twisting of the leaf but rotation of the axle is resisted by the leaf; and suspension springs are mounted between the body structure and the arms at the end of the arms remote from their pivotal mounting to the vehicle body structure and the axle is fixed to the arms between the suspension springs and the pivotal mountings.

With a suspension of this kind a considerable area is needed beneath the floor of the vehicle to accommodate components of sufficient size to provide the desired characteristic.

It is also difficult to use such a suspension for steerable vehicle wheels.

The present invention is intended to provide a suspension for a low floored vehicle which does not take up an excessive amount of underfloor space, whilst providing good ride and handling characteristics. However, the suspension should also be sufficiently versatile for use also in high floor coaches.

According to the present invention there is provided a vehicle having a rear suspension comprising a driving axle located on the vehicle body by way of a pair of longitudinal members each regidly attached to the axle and each extending on opposite sides of the axle; that first portion of each member extending on one, the first, side of the axle serving as a rigid connection between the axle and the vehicle and supporting the vehicle body at the end of the portion remote from the axle by resilient means; that second portion of each member extending on the opposide side of the axle to the first serving as extensions which are resilient in the vertical plane; each resilient extension having a cross section whose area reduces as the distance of the section from the axle increases.

The first or the second portions can extend forwardly of the axle in dependence on the particular requirements for the vehicle concerned.

Preferably the axle is powered by means of an engine disposed at the rear, or in the middle, of the vehicle.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawing which shows a suspension system for the rear wheels of a city bus or a coach.

Driving axle 10 has coupled to it drum brakes 11 adapted to receive road wheels for a vehicle part of whose lower body is shown in broken outline 1 2. The axle 10 is rigidly secured to a pair of longitudinal members 13, 1 4. Since both members 13, 1 4 are similar in form and function only member 1 3 is further described in detail. The forward end of the vehicle is indicated by arrow A. The rearwardly extending portion 1 5 of member 1 3 is a beam of constant cross sectional area which supports the vehicle body by way of an air spring 16. Rebound travel of the axle 10 is limited by shock absorber 1 7 pivotably coupled at one end to portion 1 5 and at the other to body 12.

The frontwardly extending portion 1 8 of member 1 3 is a single leaf spring which is an integral extension of portion 1 5. The leaf is tapered that is to say it has a cross section which reduces in area as the distance of the cross section from the axle 10 increases.

Leading end 1 9 of the spring is pivotably attached by a pin 20 to a mounting anchorage on the body 12.

A Panhard rod 21 is provided to locate the axle 10 laterally. Inboard end 22 of the rod 21 is coupled by a pivot pin 23 to the body 12.

The axle 10 incorporates a casing 24 for differential gearing whereby the axle is driven by way of an engine disposed to the rear of the axle and coupled to it by a conventional transmission system.

In the case of a vehicle having an engine mounted somewhat in front of the rear axle a similar arrangement to that described in connection with the specific embodiment can be used with the modification that a Panhard rod would be mounted in this case on the opposite side of the axle to that shown in the drawing; and with the differential coupled to the engine from the front, rather than the rear, of the axle.

Where the suspension is used for high floor coaches, the longitudinal members 1 3, 14 can be mounted above the axle 10 when required.

Claims

1. A wheeled vehicle having a rear suspension comprising a driving axle located on the vehicle body by way of a pair of longitudinal members each rigidly attached to the axle and each extending on opposite sides of the axle; that first portion of each member extending on one, the first, side of the axle serving as a rigid connection between the axle and the vehicle and supporting the vehicle body at the end of the portion remote from the axle directly by resilient means; the second portion of each member extending on the opposite side of the axle to the first as an extension resilient in the vertical plane; each resilient extension having a cross section whose area reduces as the distance of the section from the axle increases.

2. A vehicle as claimed in Claim 1 wherein the axle incorporates a differential gear driveable by an engine disposed behind the axle.

3. A vehicle as claimed in Claim 1 wherein the axle incorporates a differential gear driveable by an engine disposed in front of the axle.

4. A vehicle as claimed in any preceding claim wherein the longitudinal members pass beneath the axle.

5. A vehicle as claimed in any preceding claim wherein the longitudinal members are each controlled by a damper disposed between the member at or near the axle and the vehicle body or an extension thereof.

6. A vehicle as hereinbefore described with reference to and as illustrated by the accompanying drawing.