Pump having port plate pressure control

A pump, comprising:

• a housing;
• a body rotatably disposed within the housing and at least partially defining a plurality of barrels;
• a plurality of plungers associated with the plurality of barrels;
• a swashplate entirely tiltable by a swivel torque to vary a displacement of the plurality of plungers relative to the plurality of barrels;
• a port plate configured to engage an end of the body and having:
• an inlet port;
• a discharge port;
• and
• a tab protruding radially outward from a periphery of the port plate;
• a biasing piston disposed within the housing at side of the port plate closest to the discharge port and continuously supplied with pressurized fluid from the discharge port to engage the biasing piston to engage a first side of the tab and urge the port plate to rotate in a direction aligned with a rotational direction of the body, wherein the biasing piston is entirely hydraulically actuated;
• an actuator piston disposed within the housing, having a pressure area greater than a pressure area of the biasing piston, and being selectively fluidly communicated with fluid from the discharge port or a low-pressure source to engage a second side of the tab opposite the biasing piston and urge the port plate to rotate in a direction against the rotational direction of the body, wherein the actuator piston is entirely hydraulically actuated;
• and
• a 3-way valve disposed within the housing and having a pilot-operated element moveable in response to a fluid pressure at the discharge port from a first position at which fluid from the discharge port is fluidly communicated with the actuator piston, against a spring bias toward a second position at which the actuator piston is fluidly communicated with the low-pressure source.

A method of controlling a pump, comprising:

• rotating a plurality of plungers past an net port in a plate during extending strokes to draw fluid into a plurality of bores;
• rotating the plurality of plungers past a discharge port in the plate during retracting strokes to discharge fluid from the plurality of bores at an elevated pressure;
• and
• selectively moving at least one of an actuator piston and a biasing piston to engage and rotate the plate, the actuator piston and the biasing piston being entirely hydraulically actuated,
• wherein a swashplate of the pump is entirely tiltable by a rotation of the plate to change an effective displacement of the plurality of plungers within the plurality of bores.