Hydraulic control system for governing steering and implement actuators

Claim 1

A hydraulic control system for governing steering and implement actuators comprising steering control means and implement control means having steering and implement pump means respectively for selectively operating the steering and implement actuators, pressure compensating means for delivering excess fluid pressure from the steering control means to the implement control means, and emergency fluid pressure supply means for the steering control means, wherein improved emergency fluid pressure supply means comprises; (a) steering control means for supplying fluid to the steering actuator from the steering pump wherein output of the steering pump is delivered successsively through a pressure sensing switch, a check valve, a pressure compensating valve for delivering excess fluid pressure from the steering control means to the implement control means and a direction control means, (b) emergency steering control means comprising; (1) accumulator means connected through a check valve to an output supply passage of the implement pump to give charging of the accumulator means preference over pressurization of the implement actuator, (2) emergency control valve means having a solenoid control subject to energization by the pressure switch when the pressure switch senses loss of pressure in the output of the steering pump, (3) emergency control means responsive to actuation of the emergency control valve means upon energization of the solenoid for connecting output of the accumulator to input of the pressure compensating means through a pressure compensated flow control valve for pressurizing the steering control means from the implement pump, and (4) the emergency control valve being effective to prevent flow from the pressure compensating means to the implement control means as long as the solenoid remains energized.