Rear suspension for two wheelers

Field of invention

The present invention relates to "Rear suspension for two wheelers" and more particularly to a shock absorber assembly used in rear suspension used in a motorcycle.

Background of the invention

Shock absorbers are generally used in the rear suspension assembly of a two-wheeled vehicle to dampen the vibrations and absorb jerks caused due to uneven road surfaces so that a smooth riding experience is achieved. Typically motorcycles are provided with a pair of shock absorber mounted on the rear part of the motorcycles. A typical shock absorber in particular for any two-wheeler comprises a damper body and a helical compression spring pre compressed to a predetermined load value and disposed over the hydraulic cylinder of the damper body between the lower spring seat and upper spring seat of the damper body. One end of the shock absorber is hinged to rear part of the chassis of the motorcycle and the other end which is part of the hydraulic cylinder is in turn hinged to a structure firmly attached to a wheel of the said rear wheel of the motorcycle. The said pair of shock absorbers used in motorcycles absorbs or dampen road induced vibrations due to uneven road surfaces and give comfort and safety to the rider(s). Besides they also bear the vehicle load. The lower spring seat is adjustable on the hydraulic cylinder so as to adjust marginally the length of the pre-compressed spring. The spring is always pre compressed or pre loaded to pre determined load value having regard to parameters like vehicle weight, load on the vehicle and desired capacity of the shock absorber. Provision is provided in the shock absorber to adjust the pre loading of the spring. The device for adjusting the pre loading (herein after called PLA device) of a shock absorber are generally formed by a die cast, produced from a tubular element fitted with an edge profiled in the shape of a cam, while the opposite edge is profiled in the shape of a circle. When the die-cast is mounted on a vehicle, the edge of the cam is associated with the projections, while the spring of the shock absorber is mounted against the opposite edge. The cam- shaped edge of the die cast is profiled so as to define various spring preloading positions, while engaging in the appropriate projections of the shock absorber body. The tubular element of the die-cast is provided with a locating hole capable of engaging with a screw driver or a rod generally supplied with the vehicle's set of on-board tools. By using this tool the die cast may be rotated by the motorcycle user so as to move it from one pre loading position to another depending upon the requirements. Inspite of the said provision of the PLA device provided, it is not possible for the motorcycle users to have comfortable driving to meet the different condition of usage and loading condition on the vehicle. This is so especially for traders having the motorcycle whose livelihood depends on transportation of goods from one place to another for trading. There is a limitation on the desired capacity of the shock absorber available in such motorcycle. Hence there is need to provide options to such motorcycle users to carry more than what is intended and at the same time without comprising on the ride comfort and safety of the motorcycle.

Hence the objective of the invention is to provide a rear suspension for a two wheeler especially for a motorcycle with better riding comfort under different condition of loading on the said motor cycle.

Another objective of the invention is to provide a rear suspension for a motorcycle, capable of carrying sufficient goods without comprising on ride comfort and safety in the event when the motorcycle is not fully loaded or when the motorcycle is driven solo.

Another objective of the invention is to provide a rear suspension for a motorcycle with user friendly PLA device in the shock absorber (s) to facilitate to carry additional load on the vehicle.

Brief description of the invention

The invention includes a set of at least two shock absorbers mounted parallel on either side of the rear wheel of the motorcycle. All the shock absorbers are provided with a piston rod cooperating with the respective hydraulic cylinder. Each of the shock absorber units comprises a compression coil spring loaded in the required arrangement with respect to the piston rod and the hydraulic cylinder.

Each of the shock absorber unit includes a retainer for retaining the compression spring at a required level, a slot in the outer periphery of the hydraulic cylinder for providing a sliding movement to the retainer such that the compression spring with the retainer will move along the axis of the shock absorber, and a hinged lever for allowing the retainer to slide as well as to rigidly hold the retainer and the compression spring at a required level.

The present invention is accomplished by selective manipulation and activation of the spring abutment by constantly engaging the spring with the respective retainer position in the required shock absorber in proportional relation to the heavy and light load conditions.

The retainer is associated with the projections, such that the spring of the shock absorber is mounted and locked against the opposite edge. The retainer includes various locking positions, such that the spring is engaged in an appropriate projection of the shock absorber with respect to the heavy and light load requirements.

Brief description of drawings

Figure 1 illustrates a side view of a motorcycle incorporating the shock absorber assembly of the present invention.

Figure 2 illustrates a rear view of a motorcycle having the shock absorber assembly of the present invention.

Figure 3 illustrates a front view of a shock absorber unit as part of the shock absorber assembly of the present invention;

Figure 4 illustrates a side view of a shock absorber unit as part of the shock absorber assembly of the present invention.

Figure 5 illustrates the various steps in engagement of the compression spring in the shock absorber unit embodying the present invention.

Detailed description of the invention

The main purpose of this invention is to eliminate the technical shortcomings of the present available devices, by producing a selective load adjustment of shock absorber spring in a substantially simple, quick and safe manner.

The present invention is a new and improved shock absorber assembly for a motorcycle which eliminates the aforesaid problems and provides appropriate level of suspension in relation to the load conditions. Figure 1 and Figure 2 shows the improved shock absorber assembly 3 provided with selective adjustment of the compression of coil springs mounted in the shock absorbers.

The shock absorber assembly 3 includes a pair of shock absorbers 4 arranged parallely on either side of the rear wheel 2 of the motorcycle 1. All the shock absorbers 4 are provided with a piston rod 5 cooperating with the respective hydraulic cylinder 6. Each of the shock absorber units comprises a compression coil spring 7 loaded in the required arrangement with respect to the piston rod and the hydraulic cylinder.

The shock absorber unit 4 individually includes an upper mounting member 8 firmly secured to the top end of piston rod by fastening means 9 for connection with the body frame 10 of the motorcycle 1. A lower mounting member 11 is secured to the bottom end of the hydraulic cylinder 6 by another fastening means 9 for connection with the wheel-supporting member, such as, the swing fork 12 of the motorcycle. The coiled suspension spring 7, which is also known as the compression spring is arranged vertically and adjustably mounted on the external periphery of the hydraulic cylinder in the shock absorber 4.

Figure 3 and 4 shows the internal construction of the shock absorber unit 3 which include a retainer 21 for retaining the compression spring 7 at a required level, a slot 22 in the outer periphery of the hydraulic cylinder 3 for providing a sliding movement to the retainer 21 such that the compression spring with the retainer will move along the axis of the shock absorber, and a hinged lever 23 for allowing the retainer to slide as well as to rigidly hold the retainer and the compression spring at a required level.

Figure 5 shows the various steps in engagement of the compression spring in the shock absorber unit embodying the present invention. By means of selective turning of the hinged lever 23 in the respective shock absorber, the compression spring 7 get engaged through the retainer 21.

Thus the present invention is accomplished by selective manipulation and activation of the spring abutment 24 by constantly engaging the compression spring 7 with the respective retainer 21 in the required shock absorber.

The retainer 21 is associated with some projections, such that the spring 7 is mounted against the opposite edge of the retainer. The retainer includes various positions so that the spring is engaged in an appropriate projection of the shock absorber with respect to the heavy and light load requirements.

This selective activation and utilization of the spring loaded shock absorbers, makes it possible to eliminate the weakening of the springs over a prolonged period of time. Moreover, the present invention provides adjustment for shock absorber assembly without any need for spring compression tools.

Part number involved:

Motorcycle (1) Body frame (10)
Rear wheel (2) Lower mounting member (11)
Shock absorber assembly (3) Swing rear fork (12) Shock absorber (4)
Piston rod (5) Retainer (21)
Hydraulic cylinder (6) Slot (22)
Compression coil spring (7) Hinged lever (23)
Upper mounting member (8) Abutment (24)
Fastening means (9)

Claims:
1. A shock absorber assembly 3 for two wheelers comprising a set of at least two shock absorber units 4 mounted parallel on either side of the rear wheel 2 wherein it includes a retainer 21 for retaining a compression spring 7 at a required level, a slot 22 in the outer periphery of the hydraulic cylinder 6 and a hinged lever 23 for allowing the retainer 21 to slide as well as to rigidly hold the retainer 21.

2. The retainer 21 as claimed in claim 1, wherein the retainer is associated with projections such that the spring 7 of the shock absorber 4 is mounted and locked against the opposite edge.

3. The retainer 21 as claimed in claim 1, wherein the retainer includes various locking positions, such that the spring 7 is engaged in an appropriate projection of the shock absorber 4 depending on the heavy and light load requirements.

4. The shock absorber unit 4 as claimed in claim 1, wherein by means of selective turning of the hinged lever 23 in the respective shock absorber 4, the compression spring 7 gets engaged through the retainer 21.

5. The shock absorber assembly for two wheelers as claimed in claim 1 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.