Abstract:
Hydraulic control system for holding a work implement in a fixed position, said system including selectively operative shock absorbing means for negating any large force experienced by the implement on contact with an immovable object.
Abstract:
A fluid delivery system is provided having multiple hydraulic control circuits and a variable displacement pump controlled by a pressure compensated servo control which is responsive to circuit pressure for regulating pump displacement and thus provide pump output commensurate with demand from the load circuits. A control mechanism including a control valve has a pair of variable orifices in series which are created by the main control valve spool and a pressure compensated flow control spool in serial arrangement therewith precisely controls the fluid volume flow to a load system in proportion to the opening of the variable orifices. A pressure compensated servo control is adapted to move the swash plate of the pump to a minimum displacement position when all of the closed center control valves are in neutral position thereby minimizing engine horsepower loss while maintaining sufficient system pressure to provide immediate response when one of the control valves is opened.