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The present invention is a stabilizer for steering priority flow divider valves. The present invention prevents the variable displacement pump of the steering hydraulic system from destroking to zero displacement when the steering hydraulic demand rapidly varies from a high level to a low level of d

The present invention is a stabilizer for steering priority flow divider valves. The present invention prevents the variable displacement pump of the steering hydraulic system from destroking to zero displacement when the steering hydraulic demand rapidly varies from a high level to a low level of demand. The use of the present invention is especially advantageous in hydraulic systems which are close centered with pressure and flow compensation.

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1. A priority flow divider valve for use with a primary demand control valve comprising: a housing means including a first inlet, a first outlet for fluid communication with the primary demand valve, a second outlet, a bypass passage having fluid communication with said first inlet, a first bore

1. A priority flow divider valve for use with a primary demand control valve comprising: a housing means including a first inlet, a first outlet for fluid communication with the primary demand valve, a second outlet, a bypass passage having fluid communication with said first inlet, a first bore and a second bore; a supply valve spool biased within said first bore providing selective fluid communication between said first inlet and said first and second outlets; means for fluid communication from the demand valve to said second bore; means for preventing fluid communication from said second bore to the demand valve; a bypass valve spool mounted within said second bore biased to prevent fluid commuication between said bypass passage and said second bore, said bypass valve spool allowing fluid communication between said bypass passage and said second bore during fluid communication from the demand valve to said second bore; and means for retarding displacement of said bypass valve spool from a position allowing fluid communication between said bypass passage and said second bore to a position preventing fluid communication between said bypass passage and said second bore. 2. An apparatus as recited in claim 1, wherein said priority valve includes an auxiliary signal inlet intersecting with said second bore and wherein said priority valve is provided with means to prevent fluid communication between said bypass passage and said second bore during the existence of a pressure signal in said auxiliary signal inlet. 3. An apparatus as recited in claim 1, wherein said supply valve spool has a first interior passage allowing fluid communication between said first inlet and said first outlet, and said supply valve spool having a second interior passage allowing fluid communication between the demand valve and said second bore. 4. An apparatus as recited in claim 1, wherein said means for retarding the displacement of said bypass spool comprises a flow channel allowing restricted fluid communication between the demand valve and said second bore. 5. An apparatus as recited in claim 3, wherein said means for preventing fluid communication includes a check valve which further comprises a ball valve mounted within said second interior passage. 6. A priority flow divider valve with a stabilizer, for use in connection with a primary demand control valve, said priority flow divider valve comprising: a housing with a plurality of bores and passages including a first bore, a second bore, said second bore having fluid communication with said first bore, a first inlet, a first outlet, a second outlet, a first signal passage, a third outlet, and said first, and second outlet passages intersecting with said first bore, and said first inlet and said first signal passages intersecting with said first bore, and said first outlet and said first signal inlet being capable of having fluid communication with the primary demand control valve and said housing also having a first and second seal within said first bore, and said first seal defining a first pressure chamber in said first bore and said second seal defining a second pressure chamber in said first bore, and said housing also having a bypass passage intersecting with said first inlet and said third outlet; a supply valve spool slideably mounted within said first bore between said first and second seals wherein movement of said supply valve spool allowing selective fluid communication between said first inlet and said first and second outlets, said first supply valve spool having a first interior spool passage allowing fluid communication between said first inlet and said first outlet and said supply valve spool having a third interior spool passage allowing fluid communication between said first inlet and said first pressure chamber, and said supply valve spool having a second interior passage allowing fluid communication between said second pressure chamber and said second bore, and said first valve spool being biased to a preselected position; means for biasing said supply valve spool to a preselected position; a check valve allowing fluid communication from said second chamber to said second bore and preventing fluid communication from said second bore to said second chamber; a bypass valve spool slideably mounted in said second bore said bypass valve spool being biased to a position within said second bore preventing fluid communication between said bypass passage and said third outlet and said bypass valve spool allowing fluid communication between said bypass passage and said third outlet when said check valve is allowing fluid communication between said second pressure chamber and said second bore, and said bypass valve spool having a flow channel allowing restricted fluid communication between said first bore and said third outlet; and means for biasing said bypass valve spool. 7. An apparatus as recited in claim 6, wherein said first bore has a plurality of diameters. 8. An apparatus as recited in claim 6, wherein said second bore has a plurality of diameters. 9. An apparatus as recited in claim 6, wherein said means for biasing said supply valve spool to a preselected position is a coil spring. 10. An apparatus as recited in claim 9, wherein said coil spring is captured within said second pressure chamber. 11. An apparatus as recited in claim 6, wherein said means for biasing said bypass valve spool is a coil spring. 12. An apparatus as recited in claim 6, wherein said supply valve spool first interior passage comprises a first axial bore in said supply valve spool, and said supply valve spool having a first radial bore intersecting with said supply valve spool first axial bore and said first inlet, and said supply valve spool having a generally radial metering orifice intersecting with said supply valve spool first axial bore, said metering orifice allowing fluid communication between said first supply valve spool axial bore and said first outlet when said supply valve spool is at a predetermined position. 13. An apparatus as recited in claim 12 wherein there are a plurality of radial metering orifices. 14. An apparatus as recited in claim 6 wherein said supply valve spool has metering notches allowing fluid communication between said first inlet and said second outlet when said supply valve spool is at a predetermined position. 15. An apparatus as recited in claim 6 wherein said supply valve spool second interior passage comprises a second axial bore, said supply valve spool second axial bore intersecting with said second chamber and said supply valve spool having a second radial bore intersecting with said supply valve spool second axial bore opposite said second chamber, and said supply valve spool second radial bore intersecting with said housing second bore. 16. An apparatus as recited in claim 15 wherein said supply valve spool second axial bore has a plurality of diameters, and said check valve comprises a ball valve biased by a spring captured within said supply valve spool second axial bore. 17. An apparatus as recited in claim 6 wherein said bypass valve spool flow channel comprises a helical groove in said piston circumferential surface and said bypass valve spool also having a first radial bore intersecting with said helical grooves and an axial bore intersecting with said first radial orifice and said third outlet. 18. An apparatus as recited in claim 6 wherein said bypass valve spool has an axial bore intersecting with said third outlet and a second radial bore intersecting with said bypass valve spool axial bore and said bypass valve spool second radial bore being aligned with said bypass passage when said bypass valve spool is in a predetermined position allowing fluid communication between said bypass passage and said third outlet. 19. An apparatus as recited in claim 6 wherein said housing has an auxiliary signal inlet passage, said auxiliary signal inlet intersecting with said second bore, and said bypass valve spool having an axial bore and said bypass valve spool also having a first radial bore intersecting with said bypass valve spool axial bore, said bypass valve spool having a first landing intersecting with said bypass valve spool first radial bore, and said bypass valve spool first landing and first radial bore allowing fluid communication between said auxiliary signal inlet and said bypass valve spool axial bore, and said bypass valve spool having a second radial bore, said bypass valve spool second radial bore allowing fluid communication between said bypass passage and said bypass valve spool axial bore when said bypass valve spool is in a predetermined position, and wherein there is an auxiliary piston slideably mounted within said bypass valve spool axial bore, said auxiliary piston being biased to a position allowing fluid communication between said housing bypass passage and said third outlet through said bypass valve spool second radial bore and said bypass valve spool axial bore, and wherein fluid pressure in said auxiliary signal inlet acts upon said auxiliary piston to position said auxiliary piston to a location to close off said bypass valve spool second radial bore from said bypass passage. 20. A priority flow divider valve with a stabilizer, for use in connection with a steering directional control valve, said priority flow divider valve comprising: a housing with a plurality of bores and passages including a first bore, a second bore intersecting with said first bore, and a first inlet, a first outlet, a second outlet, a signal inlet, a third outlet all intersecting with said first bore, and said first outlet passage and said first signal passage being capable of having fluid communication with the steering directional control valve, and said housing also having first and second seals within said first bore defining first and second pressure chambers in said first bore, and said housing also having a bypass passage intersecting with said first inlet and said third outlet; a supply valve spool slideably mounted within said first bore between said first and second seals wherein movement of said supply valve spool allowing selective fluid communication between said first inlet and said first and said second outlets, said supply valve spool having a first interior spool passage with a plurality of generally radial metering orifices allowing fluid communication between said first inlet and said first outlet when said supply valve spool is in a predetermined position, and said supply valve spool having a second interior passage allowing fluid communication between said second pressure chamber and said second bore, and said supply valve spool being biased by a coil spring captured within said second pressure chamber to a preselected position; a unidirectional valve mounted within said supply valve spool second interior passage allowing fluid communication from said second chamber to said second bore; and a bypass valve spool slideably mounted in said second bore said bypass valve spool being biased by a coil spring to a position within said second bore to prevent fluid communication between said bypass passage and said third outlet, and said bypass valve spool allowing fluid communication between said bypass passage and said third outlet when said unidirectional valve is allowing fluid communication between said second pressure chamber and said second bore, and said bypass valve spool having helical flow channels on its periphery and a first radial bore intersecting with said helical flow channels, said bypass valve spool also having an axial bore intersecting with said bypass valve spool first radial bore and said third outlet, and said helical flow channels, said first radial bore and said second radial bore allowing restricted fluid communication between said first bore and said third outlet. 21. A priority flow divider valve with a stabilizer, for use in connection with a steering directional control valve, said priority flow divider valve comprising: a housing with a plurality of bores and passages including a first bore, a second bore intersecting with said first bore, a first inlet, a first outlet, a second outlet, a first signal inlet, a third outlet all intersecting with said first bore, and said first outlet and said first signal passage being capable of having fluid communication with the steering directional control valve, and said housing also having first and second seals within said first bore, defining first and second pressure chambers in said first bore, and said housing also having a bypass passage intersecting with said first inlet and said third outlet, and said housing having an auxiliary signal inlet intersecting with said third outlet; a supply valve spool slideably mounted within said first bore between said first and second seals wherein movement of said supply valve spool allows for selective fluid communication between said first inlet and said first and second outlets, said supply valve spool having a first interior spool passage allowing fluid communication between said first inlet and said first outlet, and said supply valve spool having a second interior passage allowing fluid communication between said second pressure chamber and said second bore, and said supply valve spool being biased to a preselected position; a check valve allowing fluid communication from said second pressure chamber to said second bore and preventing fluid communication from said second bore to said second chamber; a biased bypass valve spool slideably mounted in said second bore, said bypass valve spool having a generally axial bore intersecting with said third outlet, and said bypass valve spool having a first radial bore intersecting with said bypass valve spool axial bore, and a second radial bore axially spaced from said bypass valve spool first radial bore, said bypass valve spool second radial bore intersecting with said bypass valve spool axial bore, and said bypass valve spool having an annulus intersecting with said bypass valve spool first radial bore, and said bypass valve spool annulus and said bypass valve spool first radial bore allowing fluid communication between said auxiliary signal inlet and said bypass valve spool axial bore, and said bypass valve spool allowing fluid communication between said bypass passage and said third outlet through said bypass spool second radial bore and said bypass spool axial bore when said check valve is allowing fluid communication between said second pressure chamber and said second bore, and said bypass valve spool having a flow channel allowing restricted fluid communication between said first bore and said auxiliary signal inlet; means for biasing said bypass valve spool to a predetermined position; an auxiliary piston slideably mounted within said bypass valve spool axial bore said auxiliary piston being biased in a position allowing fluid communication between said bypass passage and said third outlet through said bypass valve spool second radial bore and said bypass valve spool axial bore, and wherein fluid pressure in said auxiliary signal inlet acts upon said auxiliary piston to position said auxiliary piston to a location within said bypass valve spool axial bore to close off said bypass valve spool second radial bore thereby preventing fluid communication between said bypass passage and said third fluid outlet; and means for biasing said auxiliary piston.