Steering control systems for C dollies and the like

摘要

In "C" dolly systems, it is conventional to provide a resistance to steer of approximately 0.3 G in order to improve the steering thereof particularly in an evasive action and to decrease the tendency of high speed off tracking. The higher this resistance to steer, the better the high speed off tracking characteristics are. However, high resistance although relatively satisfactory at high speeds, at relatively low speeds below approximately 30 miles an hour, results in the creation of severe and undue stresses and forces in the dolly and hitch structures particularly during relatively tight turning maneuvers. The present invention comprises a two phase control system. The speed of the vehicle is sensed continuously and when the speed is below approximately 30 mph (approximately 50 kph) the steering axle of the dolly is free to steer under the control of the axle steering dampening system but above 30 mph (50 kph), the axle is locked thus giving the maximum resistance to steer. It is desirable that a signal generated by the control system holds the locking mechanism out of engagement below approximately 30 mph and allows it to lock when the signal is removed at above approximately 30 mph thus providing a fail-safe feature. It is also desirable that the system does not reengage until the speed drops approximately 5 mph below the cut-out speed in order to prevent rapid cycling when travelling at approximately the cut-out speed.