Apparatus and method for determining axial stability

Abstract

An apparatus and method for determining axial stability compares measured wheel runout and axial instability parameters with prescribed tolerances to determine if the wheel suffers from excessive wheel play. Axial stability and runout is determined and displayed on a monitor screen such that an alignment technician can quickly assess both the degree of present wheel misalignment and the feasibility of attempting to perform a realignment operation without first repairing worn or damaged suspension parts. The attitude and location of a wheel are measured with the wheel set in a first position to determine a first vector having a predetermined relation to the wheel. The wheel is rolled back a number of degrees to a second position and the attitude and location thereof are measured to determine a second vector also having the predetermined relation to the wheel. Rearward axis parameters including a rearward rotational axis vector and a rearward runout vector are determined based on the first and second vectors. The wheel is rolled forward to a third position which is substantially equal to the first position and the attitude and location of the wheel are measured to determine a third vector also having the predetermined relation to the wheel. Forward axis parameters, including a forward rotational axis vector and a forward runout vector, are determined based on the second and third vectors. Dynamic stability vectors including a rotational axis stability vector and a runout stability vector are determined based on the forward and rearward axis parameters.