1. Field of the Invention
The present invention relates to cam mechanism to adjust a wheel assembly and more particularly to a cam member to adjust the caster of a steerable wheel assembly.
2. Background of the Related Art
Ball joints have long been used in automobiles to provide for rotatable motion between the spindle and control arms of a motor vehicle. Adjustments are often needed between the spindle and control arms to provide for the proper camber and caster. One of the more common ways of providing this adjustment is to provide an eccentric member which, when rotated, changes the relative position of the spindle with respect to the control arms. In another known construction, the ball joint has a ball stud with an eccentric shank which when rotated relatively moves the eccentric shank and its connected arm with respect to the ball and its connected arm.
In addition, another common way to provide adjustment is with a sleeve surrounding the ball stud having an eccentrically placed hole extending therethrough. When the sleeve is rotated, it adjustably positions the ball stud. Numerous other deficient ways to adjust caster are also known within the arts.
The problems with the prior art designs are that caster can not be adjusted without also affecting the camber, distance between upper and lower ball joints, or the pre-load of the ball joints. In addition the range of adjustment is limited and the assembly and method of adjustment is not simple. It is desirous to have an adjustment device that easily allows varied caster adjustment within a range without affecting camber and sets and holds the position of the ball joint forging while adjusting the caster angle of the wheel end.
The present invention alleviates the drawbacks of the related art. An adjustable mounting assembly for a steerable wheel assembly has a cam member rotatably disposed within a recess formed in the lower arm of a yoke assembly.
An eccentric cylinder of the cam member extends within a vertically oriented slot formed in a ball joint forging which is in turn adjustable secured to the lower arm of the yoke. By simply rotating the cam member, the eccentric cylinder engages the slot and moves the ball joint forging in a horizontal direction to adjust the caster of the wheel assembly. The vertical slot in the ball joint forging prevents vertical movement to facilitate adjustment of the caster without affecting a camber setting, the distance between the upper and lower ball joints, or ball joint pre-loading. Horizontal slots are formed in the lower arm to align with boltholes formed in the ball joint forging to allow the ball joint forging to be bolted to the lower arm over a range of horizontal positions. A method of adjusting the caster of the wheel assembly is also disclosed. The present arrangement and method allows varied caster adjustment within a range without affecting camber and maintains the position of the ball joint forging while adjusting the caster angle of the wheel end during assembly.
Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in light of the accompanying drawings.