Effect of Panhard Rod Cab Suspensions on Heavy Truck Ride Measurements

This study provides an experimental account of the effect of panhard rod suspensions on heavy truck ride, as evaluated by the B-post vertical and fore-aft accelerations. After describing the test setup, the paper will describe the details of two rear cab suspensions that are commonly used in North American trucks. Cab suspensions with dampers or similar elements that are used to provide lateral forces at the rear of the cab (called “baseline” cab suspension for the purpose of this study) and those that use a lateral link with a torsion spring at one end-commonly called “panhard rod”-are the two classes of rear cab suspensions that are considered in this study. The tests are performed on a class 8 truck that is setup in the laboratory for the purpose of providing good test repeatability and conducting an accurate design of experiment. The test results, which are analyzed in frequency domain, are compared for the two cab suspensions. They indicate that the panhard rod suspension performs better than the baseline suspension when the cab is subjected to heave inputs. When subjected to roll, however, the panhard rod cab suspension can significantly increase the B-post vertical and fore-aft accelerations, mainly due to the coupling that it causes between the roll and the heave and pitch motions of the cab.