Facilities & Services
Suspension Properties Tester
UMTRI's heavy-vehicle suspension properties tester is a permanently-installed laboratory device for measuring all of the compliance, kinematic, and coulomb friction properties of commercial vehicle suspensions germane to vehicle simulation. The system can be used to measure single or tandem axle, steering or nonsteering, and front or rear suspensions. Suspensions can be tested installed on the actual vehicle or on a frame "buck."
The facility is composed of an overhead static structure to which the vehicle chassis is rigidly fixed, a movable table that serves as the "ground" and whose vertical and roll motion exercises the suspension, and four "wheel pads," one for each wheel set of a tandem axle suspension, on which the tires of the suspension rest. Each wheel pad can either act as a frictionless surface or apply controlled shear force and moment to the tires in the ground plane. Each pad contains a load cell system for measuring the forces and moments applied to the suspension. Potentiometric transducers measure the resulting motions of each wheel and axle. The facility uses up to 48 individual transducers. Signals are gathered by a digital data acquisition system whose software allows for flexible calculation and display in real time for test monitoring or later for data reduction.
Parameters that can be determined include vertical rate, coulomb friction, roll rates (total and auxiliary), roll-center height, roll steer, lateral compliance, and lateral force and aligning moment compliance steer. Load leveling and the interaxle load transfer due to braking can be determined for tandem suspensions. For steering axles, jounce steer, wrap-up (caster) rate, and wrap-up steer may also be measured.
For more information, please see the Suspension Properties Tester Informational PDF