Title: Hydraulic brake booster with shut-off means

Abstract: A motor vehicle fluid power circuit is disclosed in which a pump driven by the engine of the vehicle assists the operator in braking the vehicle and in steering the vehicle. The circuit includes a pump, a brake booster, and a steering valve. A valve spool throttles fluid flow from the pump to the steering valve to maintain the outlet pressure of the pump at least a predetermined pressure differential above the working pressure of the brake booster. The brake booster includes a shut-off means which hydraulically isolates the pressure side of the pump from the brake booster when the brake booster reaches a predetermined shut-off pressure which is less than the relief pressure of the pump relief valve so that operation of the brake booster cannot actuate the relief valve of the pump.

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Inventors: Baker, James P. (Portland, OR, US)
Silagy, Richard J. (Parma, OH, US)

Application Number: 438624
Filing Date: 1974-02-01
Publication_date: 1976-02-10
Assignee: The Weatherhead Company (Cleveland, OH)
Primary Class(es): 91/372 60/553, 91/433, 91/454, 137/627.5
Other Classes:
US Patent Ref:

2902829	Sep, 1959	Verbrugge	91/376.
3354788	Nov, 1967	Garrison et al.	91/373.
3532027	Oct, 1970	MacDuff et al.	91/371.
3583422	Jun, 1971	Dach et al.	91/433.
3628423	Dec, 1971	Dymond	91/376.
3677138	Jul, 1972	Goscenski	91/373.
3730226	May, 1973	Nelson	137/627.
3733966	May, 1973	Brow, Jr.	91/372.
3747473	Jul, 1973	Bach et al.	91/373.
3770019	Nov, 1973	Stelzer	137/627.
3834162	Sep, 1974	Keady	60/418.
3841095	Oct, 1974	Baker	60/404.

Other Refs:
Primary Examiner: Schwadron, Martin P.
Assistant Examiner: Hershkovitz, Abraham
Attorney: McNenny, Farrington, Pearne & Gordon