Grover D Fraser

US Patent:

40764613, Feb 28, 1978

Filed:

Dec 9, 1974

Appl. No.:

5/531121

Inventors:

Harold W. Moody - Farmington CT
Clifford T. Bulkley - Glastonbury CT
Joseph A. L. N. Gagnon - Windsor Locks CT
Grover Fraser - Painted Post NY

Assignee:

Dunham-Bush, Inc. - West Hartford CT

International Classification:

F04B 4900

US Classification:

417310

Abstract:

An air motor, responsive to change in pressure of a compressed air supply line acts to control the flow of hydraulic motive fluid to a hydraulic motor which drives the capacity control slide valve of a helical screw, rotary compressor feeding the supply line. To eliminate hunting of the slide valve which shifts in response to change in compressor load, a mechanical feedback from the hydraulic motor modulates the flow of motive fluid to the hydraulic motor.