Axial piston pump with rocker cam counterbalance feed

Abstract

A rocker cam type, variable displacement, axial piston pump where working pressure fluid supplied to said housing is fed to a pair of counterbalance pockets formed in the rocker cam through fluid passages located within the rocker cam.

We claim:  
     
         1 . An axial piston pump for pumping fluid at a set working pressure which comprising a housing, a barrel rotatably mounted in the housing, a plurality of bores in the barrel, a piston mounted for reciprocation in each of said bores, a shoe mounted on the end of each piston, a rocker cam support in the housing, a rocker cam having a pair of spaced arcuate bearing surfaces pivotally mounted in complementary arcuate bearing surfaces formed in said rocker cam support, a thrust surface on said rocker cam, a holddown for clamping said piston shoes against said thrust surface wherein said shoes slide over said thrust surface when said barrel is rotated and the pistons reciprocated in their bores when the rocker cam thrust surface is angled to the axis of said barrel, a counterbalance fluid pocket formed in each of said rocker cam arcuate bearing surfaces, a first fluid passage for receiving a source of working pressure fluid formed in said housing, a second fluid passage formed in said housing and connected to said first fluid passage for conducting working pressure fluid to one of said counterbalance fluid pockets and a third fluid passage formed in said rocker cam connecting said one and the other of said counterbalance fluid pockets such that working pressure fluid from said first fluid passage supplied to said one counterbalance fluid pocket through said second fluid passage is supplied to said other counterbalance fluid pocket through said third fluid passage.  
     
     
         2 . The axial piston pump of  claim 1  further comprising a pressure compensator control.