Abstract: A hydraulically-actuated system includes a fix displacement variable delivery pump with a plurality of parallel disposed pistons that reciprocate in a pump housing the defines a high pressure portion and a low pressure area. A control device is attached to the pump housing and moveable between a first position in which the pistons displace fluid into the high pressure portion and a second position in which pistons spill fluid back to the low pressure area. The control device includes an electrically driven linear motion device, a linkage and a plurality of sleeves, one being disposed on each piston. Linear movement of the control device in turn causes linear movement of the sleeves. The position of the sleeves in turn determines the amount of output of the pump.

Abstract: A variable delivery fixed displacement pump is provided which has a rotating drive plate with a fixed angle. The drive plate has a fill passage extending between its radial outer surface and its drive surface, which allows fluid to be supplied to a fluid journal bearing. The drive plate also has a series of bearing supply passages which fluidly connect the drive surface of the drive plate with a base surface, allowing fluid to be supplied to a fluid thrust bearing. A method of pumping fluid is also provided which is comprised of the steps of reciprocating a plurality of pistons at least in part by rotating the drive plate, and by fluidly connecting a pumping chamber of the pistons to an annular groove that is part of the drive plate fill passage.

Abstract: A pump comprises a pump housing that defines an inlet and an outlet. Within the pump housing, there is a barrel that receives at least one reciprocating piston. A sleeve surrounds the annular outer surface of the piston and is movable. The temperature change within the pump is compensated for by comprising at least one of the sleeve and the barrel of a material with a lower coefficient of thermal expansion than the material comprising the piston. A clearance defined by an inner surface of the sleeve and the annular outer surface of the piston increases when the temperature is high and decreases when the temperature is low.

Abstract: A variable delivery fixed displacement pump is provided which has a rotating drive plate with a fixed angle. The drive plate has a fill passage extending between its radial outer surface and its drive surface, which allows fluid to be supplied to a fluid journal bearing. The drive plate also has a series of bearing supply passages which fluidly connect the drive surface of the drive plate with a base surface, allowing fluid to be supplied to a fluid thrust bearing. A method of pumping fluid is also provided which is comprised of the steps of reciprocating a plurality of pistons at least in part by rotating the drive plate, and by fluidly connecting a pumping chamber of the pistons to an annular groove that is part of the drive plate fill passage.