LOAD PRESSURE DUPLICATING CIRCUIT

摘要

2059658 9201162 PCTABS00010 Load sensing hydraulic systems are useful for distributing fluid from a variable displacement pump to the individual work circuits in accordance with the demand of each work circuit. Preventing load pressure from being drained from the motors of the work circuits during some operating functions heretofore required the use of a pair of pressure compensating valves and a pair of shuttle valves at each of the directional control valves. The subject load pressure duplicating circuit (49) includes a single load pressure duplicating valve (52) having an end (62) subjected to the load pressure in a signal network (51) and reduces pump pressure entering the valve to a pressure level at the output thereof equal to the load pressure. This duplicated pressure is then utilized as the control fluid for the pressure compensating valves and a displacement controller (19) of the pump. The system is greatly simplified by the use of only a single duplicating valve for a hydraulic system having a plurality of work circuits.