A hydraulic pump for supplying pressurized fluid to a hydraulic system, said pump being of a type having a housing, a plurality of cylinders within said housing and forming pumping chambers, a reciprocable piston in each of said cylinders, a cam plate for reciprocating said pistons in the suction and discharge strokes, a fluid inlet chamber for admitting fluid in said pumping chambers during a suction stroke of their respective pistons, an outlet chamber for fluid in communication with a group of said pumping chambers, through which pressurized fluid can be discharged during a discharge stroke, wherein the improvement comprises first passage means extending between said fluid outlet chambers and said fluid inlet chamber, adjustable valve means through said first passage, means directing the fluid pumped by said pistons to said outlet chamber and control means responsive to the control pressures to locate said valve means during said discharge strokes. (Machine-translation by Google Translate, not legally binding)
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