Title: Priority control valve

Abstract: A priority control valve for the priority steering control and the auxiliary circuits of the hydraulic system of a fork lift truck or the like characterized in that the housing interchangeably accommodates different priority flow control spools according to the type of steering control valve which is used i.e. a closed center steering control valve with a variable meter-in orifice in the pressure feed circuit or a closed center steering control valve with a variable meter-out orifice in the steering cylinder return circuit or an open center steering control valve with an orifice in the priority flow divider spool to determine the priority circuit flow by controlling a variable displacement pump when the priority circuit itself is operated or when the priority circuit load pressure is greater than the load pressure of the auxiliary circuit.

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Inventors: Paul, John C. (Willoughby Hills, OH, US)

Application Number: 395970
Filing Date: 1973-09-10
Publication_date: 1976-09-14
Assignee: Parker-Hannifin Corporation (Cleveland, OH)
Primary Class(es): 60/422 60/484, 91/516, 137/101
Other Classes:
US Patent Ref:

2827768	Mar, 1958	Ziskal et al.	91/412.
2892311	Jun, 1959	Gerpen	60/450.
2892312	Jun, 1959	Allen et al.	60/450.
3334705	Aug, 1967	Lam	60/422.
3391537	Jul, 1968	Smith	60/422.
3410295	Nov, 1968	Malott	91/28.
3470694	Oct, 1969	Budzich	60/427.
3543516	Dec, 1970	Treichel	60/422.
3584538	Jun, 1971	Peterson	91/421.
3662548	May, 1972	Suzuki et al.	91/412.
3703186	Nov, 1972	Brewer	137/101.
3726093	Apr, 1973	Malott	60/445.
3760830	Sep, 1973	Fritzsche et al.	137/101.

Other Refs:
Primary Examiner: Croyle, Carlton R.
Assistant Examiner: Look, Edward
Attorney: Donnelly, Maky, Renner & Otto