This paper presents a test rig adopted for a basic investigation on the shimmy phenomenon that, even if with some differences, characterizes the dynamic behavior of many mechanical systems such as aircraft landing gear, motorcycles, towed vehicles, etc..
The test rig is constituted of a castor derived from a scooter front assembly, joined to a rigid steel frame so that it can vertically translate and rotate around the steering axis; the castor wheel rolls on a flat track belt driven by an electric motor. The rake angle, the steer damping, the vertical load, the inertia proprieties and the wheel/tire characteristics can be adjusted to experimentally investigate their influence on the castor dynamic behavior.
The paper deals with the dynamic behavior of a castor characterized by a low lateral stiffness and a simple procedure to identify its vibrating modes is presented. It is also shown a numerical model adopted to test the sensitivity of the system to the parameters changes.
