INPUT CONTROL DEVICE FOR HYDRAULIC PUMP

摘要

PROBLEM TO BE SOLVED: To perform a horse power control without ussizing a spring to energize a spool by providing a first stepped part wherein a first piston forms a pressure receiving surface of a variable pump and a second stepped part wherein a second piston forms a pressure receiving surface for reducing a horse power. SOLUTION: A first stepped part is provided to have a first piston 32 forming a pressure receiving surface 34 for a variable pump and a second stepped part is provided to have a second piston 33 forming a pressure receiving surface 36 for reducing a horse power. Discharge pressure of an auxiliary pump 14 is exerted on a pressure receiving surface 36 for reducing a horse power of the second piston 33 and simultaneously the self pressure of a hydraulic pump 2 is exerted on the pressure receiving surface 34 for a variable pump of the first piston 32. The second piston 33 and the first piston 32 are moved against the force of a spring 26 to energize the spool 25 of a regulator 31. This constitution controls desired horse power reduction by shifting the spool 25 without increasing the size of the spring 26 and needing an proportional pressure reducing solenoid valve.