Hydraulic radial piston pump intake porting arrangement

A hydraulic radial piston pump having a slider block mounted on an eccentric of a rotary shaft in a hydraulic fluid supplied cavity, a piston mounted in a cylinder disposed radially to the shaft, the piston having a flat working face at one end operating in the cylinder and a flat pad at an opposite end slidably engaged by a flat face of the slider block so as to force the piston outward on a compression stroke on shaft rotation, a yoke retaining the piston to the slider block so as to retract the piston inward on an intake stroke on shaft rotation characterized by intake porting means for communicating the cavity with the working end of the piston comprising an intake passage extending through the piston from the working end to the pad end, an elongated intake slot in the face of the slider block extending from a point continuously open to the cavity to a point that opens to the intake passage at the pad end on relative movement of the slider block during the intake stroke to just prior to the compression stroke, the annular faces at the working and pad ends of the piston having substantially equal areas to prevent hydraulic film from developing between the slider block and pad and thereby prevent their separation during compression, and the yoke being a one-piece four-sided part that fits over the slider block and has a slot through which the piston extends and is engaged on opposite sides by the piston pad to retract the piston.