Land vehicles – Wheeled – Occupant propelled type
Reexamination Certificate
2003-04-03
2004-09-07
Hurley, Kevin (Department: 3611)
Land vehicles
Wheeled
Occupant propelled type
C180S219000
Reexamination Certificate
active
06786499
ABSTRACT:
FIELD OF THE INVENTION
The invention is directed generally to suspension systems, and more particularly, to motorcycle suspension systems.
BACKGROUND
A conventional motorcycle, which is commonly referred to as a bike, typically includes at least one shock absorber on both the front and rear wheels for absorbing forces caused by changes in terrain or obstacles often encountered during use. Most often, at least one shock absorber, if not two or more, is positioned between the frame and the front wheel. The shock absorbers are generally juxtaposed and positioned parallel to the support arms to which the front wheel is attached. This configuration enables the shock absorbers to absorb forces that are parallel and perpendicular to the ground on which the motorcycle rests.
Configuring shock absorbers in this manner works well with motorcycles having support arms, which are also referred to as legs, that are orientated between a position that is generally orthogonal to a ground surface and a position at or less than an angle of about 36 degrees relative to a vertical axis. This angle is commonly referred to as a castor angle or rake. As the rake is increased beyond 36 to 40 degrees, shock absorbers positioned generally parallel to the support arms function poorly. This poor function is attributable to excessive rake and lateral forces on the fork, which increase friction on the support arms. Excessive rake limits a shock absorber's ability to slide easily, thereby defeating a shock absorber's intended function and ability to absorb forces caused by terrain and braking. Motorcycles having support arms positioned at angles greater than about 36 degrees relative to a vertical axis are commonly referred to as choppers.
When a shock absorber is positioned at an angle that is less than about 36 degrees, the force vectors generated by a change in terrain or by an obstacle encountered by the front wheel are absorbed by the shock absorber of the motorcycle. However, when a shock absorber is positioned at an angle that is greater than about 36 degrees relative to a vertical axis, the shock absorber is not positioned to absorb the force vector that is produced in the generally vertical direction. As a result, such vertical vector forces causes friction in the shock absorbers that inhibits proper function.
Thus, a need exists for a suspension system configured for use with motorcycles having rake greater than about 36 degrees.
SUMMARY OF THE INVENTION
This invention is directed to a suspension system for a front wheel of a vehicle, such as a motorcycle. The suspension system may include a support arm assembly and one or more movement limiting devices, such as a shock absorber. The support arm assembly may include at least one support arm for supporting a front wheel, a support bracket, and a neck. The support arm may be coupled to the support bracket, and the support bracket may be pivotably coupled to the neck so that the support bracket can rotate about an axis that is generally parallel to a longitudinal axis of the support arm. The neck may be rotatably coupled to a frame at a pivot so that the support arm assembly may rotate around an axis generally orthogonal to a longitudinal axis of the motorcycle and generally orthogonal to the axis about which the support bracket may rotate. The support arm assembly may have a first end for supporting the front wheel and a second end that is generally opposite to the first end. The support arm may be pivotably coupled to the frame at the pivot that is proximate to the second end of the support arm so that the support arm can rotate around an axis that is generally orthogonal to a longitudinal axis of the frame and generally orthogonal to a longitudinal axis of the at least one support arm.
The suspension system may also include at least one movement limiting device having a first end configured to be attached to the frame and a second end coupled to the support arm assembly proximate to the second end. In one embodiment, the movement limiting device is coupled to the support arm assembly between the second end of the support arm assembly and the pivot. In another embodiment, the movement limiting device is coupled to the support arm assembly between the first end of the support arm assembly, which is configured to be coupled to a front wheel and the pivot.
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Akerman & Senterfitt
Dixon Michael K.
Hurley Kevin
Nelson Gregory A.
Tempest Cycles, Inc.
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