John L Acheson

US Patent:

43481590, Sep 7, 1982

Filed:

Jan 7, 1980

Appl. No.:

6/110041

Inventors:

John L. Acheson - Franklin WI

Assignee:

Rexnord Inc. - Milwaukee WI

International Classification:

F04B 4908
F04C 1504

US Classification:

417220

Abstract:

A vane-type variable displacement pump is controlled by a first stage servo-valve. The servo-valve is controlled by a second stage which may optionally include devices which provide any of several desired control effects.

US Patent:

42928052, Oct 6, 1981

Filed:

Sep 24, 1979

Appl. No.:

6/078332

Inventors:

John L. Acheson - Franklin WI

Assignee:

Rexnord Inc. - Milwaukee WI

International Classification:

F04B 126
F04B 4908
F16H 3946

US Classification:

60450

Abstract:

A hydraulic system includes an actuator and a motor driven pump. A servo-control valve adjusts the displacement of the pump and provides a stable response to pump output pressure variations. The servo-valve is adapted for the addition of a control piston which operates against the spool of the servo-valve to modulate its operation in response to a moderate pressure drop across a restriction placed in the line from the pump to the actuator.