Speed sensitive control system for slipping clutch

Claim 1

In a drive train including a prime mover, an input shaft coupled to the prime mover, a primary output shaft, a hydraulically actuated slipping clutch including an actuating chamber and providing a variable coupling between the input shaft and primary output shaft, and auxiliary motor means coupled for rotation with the input shaft and having variable power requirements which are at least momentarily substantial relative to available power from the prime mover, a control system for the slipping clutch comprising a source of fluid under pressure, means forming an annular fluid chamber adjacent a rotating member in the drive train on the input side of the slipping clutch, pitot means having an inlet opening arranged in circumferentially facing relation in the annular fluid chamber and an outlet passage wherein fluid pressure is proportional to rotating speed of the drive train member, valve means communicating the source with the actuating chamber for the slipping clutch, the valve means being in responsive communication with the outlet passage of the pitot means for regulating pressurization of the actuating chamber in the slipping clutch relative to operating speed of the prime mover, and a manually operable biasing means operatively coupled with the valve means for limiting response of the valve means to the pitot means.