Progressive Weight Mechanism for Baja SAE Traction Events

A feature of Baja SAE, and other off-road racing series, is a dynamic traction event. Usually some sort of pull-test device is towed in this event, and design of this device has a controlling influence on the performance capability of each vehicle in the field. Pull-test devices are usually designed to be progressive so that starting is easy, but the pulled load gets higher the further the tow proceeds. Pull-test devices must also be mechanically designed to suit the efficient operation of the traction event (hitching and resetting). This paper develops the operating and design theory of a new pull-test device, the log pull.