On the Application of Straight-Line Linkages to Vehicle Suspension

Four-bar linkages which generate approximate straight-line motion are investigated for use in vehicle suspension. The particular suspension geometry studied is the beam-axle type, leading to systems with two degrees of freedom of body roll motion relative to the axle. Kinetostatic analyses of these spring-restrained systems are carried out for a number of cases involving different combinations of loads and linkage geometry. From the predicted orientation of the body relative to the axle various vehicle dynamics parameters can be calculated, including roll center location and roll stiffness. It is found that these parameters, which are normally considered constant, are functions of the suspension linkage, jounce/rebound, and roll angle. Conditions under which the linkage types produce comparable roll performance are established.