GB2037678A

GB2037678A - Motor cycles

Info

Publication number: GB2037678A
Application number: GB7942509A
Authority: GB
Original assignee: Matthews R E
Current assignee: Matthews R E
Priority date: 1978-12-18
Filing date: 1979-12-10
Publication date: 1980-07-16

Abstract

A motor cycle has a box section frame beam 2 carrying a front wheel fork at one end and an engine mounting bracket 13 at the other end, a trailing arm 3 carrying the rear wheel being pivoted to the bracket 13 and resilient suspension means in the form of a rubber cone and a telescopic damper being provided between the trailing arm 3 and the bracket 13. An extension of the beam 2 carries a rider's seat overlying the rear wheel. The sub- assembly comprising the engine 7 and rear suspension is readily disconnectable from the beam 2, being attached thereto at locations 11, 12. The beam 2 may house both fuel and oil. <IMAGE>

Description

SPECIFICATION Improvements in or relating to motor cycles This invention relates to a motor cycle and a suspension system for same.

It is an object of this invention to provide a motor cycle or simplified construction which has high structural strength without reliance on a complex internal framework for load bearing.

A futher object of the invention is to provide a suspension system for a motor cycle utilizing both a single compression spring and separate damper unit in connection with the engine and transmission mounting structure.

According to a first aspect of this invention there is provided a motor cycle having a box section structure carrying front wheel forks at one end and including a trailing arm rear wheel connection at or near the other end with an integral resilient suspension means provided between the trailing arm and box section structure, an extension forming a seat for a rider being connecting with the box structure and lying over the rear wheel.

This construction provides an arrangement of light-weight with a monocoque beam forming the principle load bearing component.

The engine, transmission, rear suspension and rear drive wheel may be releasably secured as a combined primary sub-assembly to the remaining structure, that is the chassis, systems, seat and front suspension secondary sub assembly, in a plurality of locations. Preferably, three such mounting locations are provided in pairs on either side of the motor cycle. One is preferably in the region of the cylinder head and two on the engine to rear suspension or drive wheel mounting structure; all of which may correspond to three pairs of mounting points on one frame structure monocoque beam.

A rapid engine/transmission/rear wheel sub assembly release facility is thus provided which allows rapid initial assembly in addition to easier motor cycle maintenance and repairs.

According to a second aspect of this invention there is provided a suspension system for a motor cycle in which a rear wheel trailing arm is pivotally connected at a first location to an engine mounting structure and to a damper unit at a second location, said damper unit being pivotally connected at its other end to said engine mounting structure, a compression spring being located between a face of said engine mounting structure and a face of the trailing arm, the arrangement being such that upward displacement of the trailing arm compresses said spring and activates said damper unit.

The engine mounting structure is preferably one or more box section brackets securing the engine unit to the rear wheel in a motor cycle. The compression spring may be a rubber spring, the base of which bears upon a face of the engine mounting structure and is subject to compression exerted through a corresponding face of the trailing arm. Atelescopic damper unit is pivotally connected through the trailing arm to the engine mounting structure. Both first and second pivot locations of the trailing arm may be in the region of the motor cycle engine, displaced from the rear wheel axle.

This suspension system dispenses with the conventional pair of dampers between the rear wheel and motor cycle frame. Consequently it is a simple matter to remove the engine, suspension and rear wheel sub assembly from the remaining frame structure.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a side view of a motor cycle according to the first aspect of the invention, Figure 2 is a side view of a motor cycle according to the first aspect of the invention showing the mounting system, and Figure 3 is a side view of the suspension system in accordance with the second aspect of the invention.

Referring firstly to Figure 1, the motor cycle shown has a front wheel fork assembly 1 connected to one end of a pressed steel monocopue beam 2 which carries trailing arms 3 for supporting the rear wheel 4. Suspension is effected by rubber cones (not shown) between the beam 2 and each trailing arm 3.

The beam 2 also has a further beam 5 extending backwardly over the rear wheel and forming the rider's seat 6. The beam 5 is constructed as a fuel tank. The engine unit 7 is slung below beam 2 with appropriate integral gear box and drive to the rear wheel.

The beams may conveniently house a battery or other parts of the motor cycle.

The construction is inexpensive and easy to manufacture from sheet metal.

The beams may be totally sealed and directly house fuel and oil, the large area affording good cooling.

A luggage carrier may be included at 8.

Referring to Figure 2 the motor cycle engine 7 is secured to an engine mounting bracket 13 from which the trailing arm 3 extends. Mounting points 9 are provided at the top of this bracket 13 and co-operate with similar mounting points 12 on the same beam 2 of the frame structure. An engine mounting point 10 is located near the top of the engine 7 and co-operates with a similar mounting point 11 on the beam 2 of the frame structure.

As only three mounting points are provided, the engine and rear wheel sub-assembly is quickly releasable from the corresponding chassis, seat and front suspension sub-assembly.

Referring to Figure 3, an engine mounting bracket 13 is secured to the frame structure beam 2 at mounting points 9. The trailing arm 3 carrying the rear wheel 4 is pivotally secured at axle 19 to the bracket 13. A rubber compression spring 16 is secured to a face structure 20 of the mounting bracket 13. A resilient member within an extension 14 of the trailing arm 3 has a corresponding face structure 15 which bears against the compression spring. Between the trailing arm extension 14 and the mounting structure 13, a telescopic damper unit 17 is pivotally fastened at 18 and 21 respectively.

Upwards displacements of the rear wheel 4 causes the trailing arm 3 to pivot about axle 19, wherein the compression spring 16 is compressed by the face structure 15 within the trailing arm extension 14. The resulting motion is damped by extension or compression of the damper unit 17.

A compact and concealed suspension system is thus provided which enables an engine and rear wheel sub-assembly to be easily removed from the remaining frame structure.

Claims

1. A motor cycle having a box section structure carrying front wheel forks at one end and including a trailing arm rear wheel connection at or near the other end with an integral resilient suspension means provided between the trailing arm and box section structure, an extension forming a seat for a rider being connected with the box structure and lying over the rear wheel.

2. A motor cycle in accordance with Claim 1 wherein a front wheel fork assembly is connected to one end of a pressed steel monocoque beam which carries the or each trailing arm.

3. A motor cycle in accordance with Claim 2 wherein the monocoque beam has a secondary beam extending over the rear wheel and forming the rider's seat.

4. A motor cycle in accordance with Claim 2 or 3 wherein suspension is effected by rubber cones between the monocoque beam and the trailing arm.

5. A motor cycle in accordance with any preceding claim wherein at least part of the box section structure is constructed as a fuel tank.

6. A motor cycle in accordance with any preceding claim wherein the box section structure is totally sealed and directly houses both fuel and oil.

7. A motor cycle in accordance with any preceding claim wherein the engine, transmission, rear suspension and rear drive wheel are releasable secured as a combined primary sub-assembly to the chassis, systems, seat and front suspension secondary sub-assembly.

8. A motor cycle in accordance with Claim 7 wherein primary a-nd secondary respective subassemblies are releasably secured at three mounting locations.

9. A motor cycle in accordance with Claim 8 wherein each mounting location is on one box section or monocoque beam of the primary subassembly, whereas the secondary sub-assembly includes one mounting location at the top of the engine and two mounting locations on an engine mounting structure securing the power unit to the rear wheel.

10. A suspension system fora motor cycle in which a rearwheeltrailing arm is pivotallycon- nected at a first location to an engine mounting structure and to a damper unit at a second location, said damper unit being pivotally connected at its other end to said engine mounting structure, a compression spring being located between a face of said engine mounting structure and a face of the trailing arm, the arrangement being such that upward displacement of the trailing arm compresses said spring and actuates said damper unit.

11. A suspension system in accordance with Claim 10 wherein the engine mounting structure comprises one or more brackets of box section structure securing the engine unit to the rear wheel and a chassis sub assembly.

12. A suspension system in accordance with Claim 10 or 11 wherein the compression spring is a rubber spring, the base of which bears against a face of the engine mounting structure and is subject to compression exerted through a corresponding face of the trailing arm.

13. A suspension system in accordance with any one of Claims 10 to 12 wherein both first and second pivotal connection locations are in close proximity to the motor cycle engine.

14. A suspension system in accordance with any one of Claims 10 to 13 wherein an extended portion of the trailing arm houses a resilient member having a face structure which bears against the compression spring.

15. Asuspension system in accordance with Claim 14 wherein a telescopic damper unit is pivotally connected between the trailing arm extension and the engine mounting structure.

16. A motor cycle having a box section structure substantially as herein described with references to and as illustrated in any one of the accompanying drawings.

17. A suspension system for a motorcycle substantially as herein described with reference to and as illustrated in Figures 2 or 3 of the accompanying drawings.