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A hydraulic drive and fluid control system for a mechanism having at least two fluid actuated cylinder includes a bi-directional motor/gear pump. A monolithic block manifold has intersecting bores formed therein in which valving and control mechanism for the fluid circuit is mounted. The fluid contr

A hydraulic drive and fluid control system for a mechanism having at least two fluid actuated cylinder includes a bi-directional motor/gear pump. A monolithic block manifold has intersecting bores formed therein in which valving and control mechanism for the fluid circuit is mounted. The fluid control system includes a variety of elements for providing smooth action of the cylinders at start, stop, and intermediate operations. These include piston-style accumulators, self-actuating fluid flow rate control valves and cushion valves.

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1. A fluid control system for use with a chair having an upper structure comprising a seat and a back rest, said upper structure adapted to be raised and lowered by means of a first fluid actuated cylinder and said back rest adapted to be tilted by means of a second fluid actuated cylinder, wherein

1. A fluid control system for use with a chair having an upper structure comprising a seat and a back rest, said upper structure adapted to be raised and lowered by means of a first fluid actuated cylinder and said back rest adapted to be tilted by means of a second fluid actuated cylinder, wherein greater fluid pressure is required to actuate the first cylinder to raise the upper structure than is required to tilt the back rest, the system comprising a first fluid supply circuit connected to said first cylinder and a second fluid supply circuit connected to said second cylinder, a bi-directional pump operatively connected to said first and second fluid supply circuits such that operation of the pump in a first direction supplies fluid under pressure to said first circuit and operation of the pump in an opposite second direction supplies fluid under pressure to said second circuit, and a reversible electric motor capable of supplying greater torque when operated in a first direction than in an opposite second direction, said motor being operatively connected to said pump to drive said pump in its first direction when said motor is operated in its first direction and to drive said pump in its second direction when said motor is operated in its second direction. 2. The system of claim 1, which further comprises a fluid holding reservoir from which said pump may draw fluid, and a series of check valves operable to open said first fluid supply circuit to permit fluid to be pumped from said reservoir to the first cylinder and to close the second fluid supply circuit when said pump is operated in said first direction. 3. The system of claim 2, wherein said series of check valves is operable to open said second fluid supply circuit to permit fluid to be pumped from said reservoir to the second cylinder and to close the first supply circuit when said pump is operated in said second direction. 4. The system of claim 1, wherein a fluid pressure accumulator is connected in a supply circuit between said pump and cylinder. 5. The system of claim 1, which further comprises a first fluid return circuit for said first cylinder and a second fluid return circuit for said second cylinder, a first selectively operable valve in said first return circuit operable in a closed position to close said circuit to the return of fluid from the first cylinder to the reservoir and in an open position to permit return of fluid to the reservoir, and a second selectively operable valve in said second return circuit operable in a closed position to close said circuit to the return of fluid from the second cylinder to the reservoir and in an open position to permit return of fluid to the reservoir. 6. A fluid control system for use with a chair having an upper structure comprising a seat and a back rest, said upper structure adapted to be raised and lowered by means of a first fluid actuated cylinder and said back rest adapted to be tilted by means of a second fluid actuated cylinder, wherein greater fluid pressure is required to actuate the first cylinder to raise the upper structure than is required to hit the back rest, the system comprising a first fluid supply circuit connected to said first cylinder and a second fluid supply circuit connected to said second cylinder, a bi-directional pump operatively connected to said first and second fluid supply circuits such that operation of the pump in a first direction supplies fluid under pressure to said first circuit and operation of the pump in an opposite second direction supplies fluid under pressure to said second circuit, and a reversible electric motor capable of supplying greater torque when operated in a first direction than in an opposite second direction, said motor being operatively connected to said pump to drive said pump in its first direction when said motor is operated in its first direction and to drive said pump in its second direction when said motor is operated in its second direction, wherein said pump is a gear pump including a crescent gear set comprising an inner pinion gear having a selected diameter and number of radially outwardly extending outer teeth, an outer ring gear having a greater diameter than said pinion gear and a greater number of radially inwardly extending inner teeth with only a minor portion of said inner teeth meshing with the outer teeth of the pinion gear at a given time, a crescent shaped member interposed between said pinion gear and ring gear, and said pinion gear being operatively connected to said motor for powered rotation by said motor with outer said ring gear being rotatably driven about said pinion gear. 7. A fluid control system for use with a chair having an upper structure comprising a seat and a back rest, said upper structure adapted to be raised and lowered by means of a first fluid actuated cylinder and said back rest adapted to be tilted by means of a second fluid actuated cylinder, wherein greater fluid pressure is required to actuate the first cylinder to raise the upper structure than is required to tilt the back rest, the system comprising a first fluid supply circuit connected to said first cylinder and a second fluid supply circuit connected to said second cylinder, a bi-directional pump operatively connected to said first and second fluid supply circuits such that operation of the pump in a first direction supplies fluid under pressure to said first circuit and operation of the pump in an opposite second direction supplies fluid under pressure to said second circuit, and a reversible electric motor capable of supplying greater torque when operated in a first direction than in an opposite second direction, paid motor being operatively connected to said pump to drive said pump in its first direction when said motor is operated in its first direction and to drive said pump in its second direction when said motor is operated in its second direction, wherein a fluid pressure accumulator is connected in a supply circuit between said pump and cylinder, and said accumulator comprises an elongate cylinder chamber, a pressure fluid inlet at one portion of said chamber, a piston sealingly located in said chamber for sliding movement axially of the chamber, with one face of the piston directed toward said pressure fluid inlet and an opposite face directed away from the pressure fluid inlet, biasing mechanism yieldably urging said piston in the direction of said fluid inlet, and a low pressure fluid outlet from the chamber on the side of the piston toward which said opposite face is directed. 8. The system of claim 7, wherein said low pressure fluid outlet comprises a restricted outlet orifice of selected size to control the flow of fluid from the chamber. 9. The system of claim 7, wherein said accumulator further comprises a pressure relief valve extending through said piston operable to release excess pressure from the pressure inlet side of said piston to the low pressure outlet side of the piston. 10. The system of claim 9, wherein said pressure relief valve comprises a relief valve bore extending through said piston from said one face to said opposite face, a valve member located in said relief valve bore for shifting between a first position closing said relief valve bore to fluid flow therethrough and a second position permitting fluid flow therethrough, and biasing mechanism urging said valve member toward said first position, said biasing mechanism being yieldable to permit movement of said valve member to its second position upon a pre-selected pressure being exerted against said valve member by fluid on the inlet side of said piston. 11. The system of claim 9, wherein said biasing mechanism comprises a spring. 12. A fluid control system for use with a chair having an upper structure comprising a seat and a back rest, said upper structure adapted to be raised and lowered by means of a first fluid actuated cylinder and said back rest adapted to be tilted by means of a second fluid actuated cylinder, wherein greater fluid pressure is required to actuate the first cylinder to raise the upper structure than is required to tilt the back rest, the system comprising a first fluid supply circuit connected to said first cylinder and a second fluid supply circuit connected to said second cylinder, a bi-directional pump operatively connected to said first and second fluid supply circuits such that operation of the pump in a first direction supplies fluid under pressure to said first circuit and operation of the pump in an opposite second direction supplies fluid under pressure to said second circuit, and a reversible electric motor capable of supplying greater torque when operated in a first direction than in an opposite second direction, said motor being operatively connected to said pump to drive said pump in its first direction when said motor is operated in its first direction and to drive said pump in its second direction when said motor operated in its second direction, a first fluid return circuit for said first cylinder and a second fluid return circuit for said second cylinder, a first selectively operable valve in said first return circuit operable in a closed position to close said circuit to the return of fluid from the first cylinder to the reservoir and in an open position to permit return of fluid to the reservoir, and a second selectively operable valve in said second return circuit operable in a closed position to close said circuit to the return of fluid from the second cylinder to the reservoir and in an open position permit return of fluid to the reservoir, wherein fluid returns from a cylinder under pressure and which further comprises a self-actuating fluid flow rate control valve comprising a chamber defined by a chamber wall with a fluid inlet opening at one region of the chamber and a fluid outlet port extending through the chamber wall spaced from the inlet opening, a plunger mounted for movement in the chamber between the inlet opening and outlet port, said plunger having a head portion facing in the direction of said inlet opening to be acted upon by fluid pressure to urge the plunger to move from a first position spaced from the outlet port toward a second position adjacent the port to inhibit outflow of fluid from the chamber through the outlet port, and biasing mechanism operable to yieldably urge the plunger toward its first position. 13. The system of claim 12, wherein said plunger is movable to multiple different positions between said first and second position adjacent the port to produce variation in out flow responsive to fluid inlet pressures. 14. The system of claim 12, wherein the head portion of said plunger has a flow rate orifice extending therethrough of a selected opening size to produce a selected rate of fluid flow. 15. The system of claim 14, wherein a selectively operable valve has a fluid flow port of a selected fluid flow size when opened and said flow rate orifice is smaller than said fluid flow port. 16. The system of claim 14, wherein said control valve further comprises an elongate hollow cylindrical sleeve defining said chamber wall, said inlet opening is provided adjacent one end of said sleeve, and said plunger is located for sliding movement axially within said sleeve. 17. The system of claim 16, which further comprises a stop for limiting the movement of said plunger in the direction of said inlet opening. 18. The system of claim 16, wherein said sleeve is substantially closed other than for said inlet opening and said outlet port. 19. The system of claim 18, wherein said inlet opening is defined at one end of said sleeve, the opposite end of said sleeve is closed, and said biasing mechanism comprises a spring interposed between said closed end of the sleeve and said plunger. 20. A fluid control system for use with a chair having an upper structure comprising a seat and a back rest, said upper structure adapted to be raised and lowered by me ans of a first fluid actuated cylinder and said back rest adapted to be tilted by means of a second fluid actuated cylinder, wherein greater fluid pressure is required to actuate the first cylinder to raise the upper structure than is required to tilt the back rest, the system comprising a first fluid supply circuit connected to said first cylinder and a second fluid supply circuit connected to said second cylinder, a bi-directional pump operatively connected to said first and second fluid supply circuits such that operation of the pump in a first direction supplies fluid under pressure to said first circuit and operation of the pump in an opposite second direction supplies fluid under pressure to said second circuit, and a reversible electric motor capable of supplying greater torque when operated in a first direction than in an opposite second direction, said motor being operatively connected to said pump to drive said pump in its first direction when said motor is operated in its first direction and to drive said pump in its second direction cylinder and a second fluid return circuit for said second cylinder, a first selectively operable valve in said first return circuit operable in a closed position to close said circuit to the return of fluid from the first cylinder to the reservoir and in an open position to permit return of fluid to the reservoir, and a second selectively operable valve in said second return circuit operable in a closed position to close said circuit to the return of fluid from the second cylinder to the reservoir and in an open position to permit return of fluid to the reservoir, wherein a fluid return circuit comprises a cushion valve assembly comprising a valve chamber defined by a chamber wall, a fluid pressure inlet region adjacent one portion of said chamber, a fluid outlet port extending through said chamber wall in a region spaced front said inlet region, and a plunger assembly located in said chamber for movement between a first position adjacent said outlet port to inhibit flow of fluid from said chamber through said port, and a second position permitting substantially free flow of fluid from said chamber through said port, and biasing mechanism urging said plunger assembly toward said first position and yieldable to permit movement of said plunger assembly to said second position upon a pressure above a selected pressure being exerted from said fluid inlet region on said plunger assembly. 21. The system of claim 20, wherein said plunger is movable to multiple different positions between said first and second positions. 22. The system of claim 20, wherein said plunger assembly comprises a plunger body having a substantially impermeable sidewall configuration substantially complementary to the chamber wail configuration to permit sliding movement of the plunger body within the chamber, a substantially closed head portion at one end of the plunger body facing in the direction of said inlet region, an internal bore opening toward the opposite end of said plunger body from said inlet region, a fluid flow control orifice formed adjacent said head portion permitting controlled flow of fluid into said internal bore, and a normally-closed check valve mounted in said internal bore which is urged to an open position to permit fluid flow through said orifice to said opposite end of said valve assembly. 23. A fluid control system for use with a chair having an upper structure comprising a seat and a back rest, said upper structure adapted to be raised and lowered by means of a first fluid actuated cylinder and said back rest adapted to be tilted by means of a second fluid actuated cylinder, wherein greater fluid pressure is required to actuate the first cylinder to raise the upper structure than is required to tilt the back rest the system comprising a first fluid supply circuit connected to said first cylinder and a second fluid supply circuit connected to said second cylinder, a bi-directional pump ope ratively connected to said first and second fluid supply circuits such that operation of the pump in a first direction supplies fluid under pressure to said first circuit and operation of the pump in an opposite second direction supplies fluid under pressure to said second circuit, and a reversible electric motor capable of supplying greater torque when operated in a first direction than in an opposite second direction, said motor being operatively connected to said pump to drive said pump in its first direction when said motor is operated in its first direction and to drive said pump in its second direction when said motor is operated in its second direction, a substantially monolithic body in which fluid routing circuits are formed and chambers are provided for receiving a plurality of valve assemblies for controlling fluid flow, said body having a plurality of bores formed therein which extend inwardly from external surface regions of the body, but do not extend fully through the body, with selected ones of said plurality of bores intersecting to produce desired fluid flow channels in the fluid supply and return circuits in the system. 24. The system of claim 23, which further comprises a plurality of valve assemblies for controlling fluid flow in the system, and a majority of said valve assemblies are operatively mounted in selected ones of said bores formed in said monolithic body. 25. The system of claim 23, wherein said pump comprises a gear pump comprising a pair of motor driven gear elements having meshing gear teeth and said monolithic body has a pump receiving cavity formed therein defining a housing for gear pump elements and having pump outlet openings machined in said body in communication with said cavity. 26. A fluid control system for use with a chair having an upper structure comprising a seat and a back rest, said upper structure adapted to be raised and lowered by means of a first fluid actuated cylinder and said back rest adapted to be tilted by means of a second fluid actuated cylinder, wherein greater fluid pressure is required to actuate the first cylinder to raise the upper structure than is required to tilt the back rest, the system comprising a first fluid supply circuit connected to said first cylinder and a second fluid supply circuit connected to said second cylinder, a bi-directional pump operatively connected to said first and second fluid supply circuits such that operation of the pump in a first direction supplies fluid under pressure to said first circuit and operation of the pump in an opposite second direction supplies fluid under pressure to said second circuit, and a reversible electric motor capable of supplying greater torque when operated in a first direction than in an opposite second direction, said motor being operatively connected to said pump to drive said pump in its first direction when said motor is operated in its first direction and to drive said pump in its second direction when said motor is operated in its second direction, and a manifold having at least three fluid flow bores opening in adjacent regions to a surface of said manifold, with a first bore opening being disposed between a second and a third bore opening, a selectively operable valve, and an adapter interposed between the manifold and the valve, the adapter comprising an adapter body having a lower portion sealingly coupled to said manifold, a central bore extending through said body positioned to communicate at one of its ends with said first bore and open at its opposite end at another region of said adapter body, a substantially continuous channel formed in the lower portion of the adapter body configured to overlie and provide fluid communication between the second and third bore openings while being segregated from said first bore opening a side bore extending through said adapter body from said channel to another region of said adapter body, and mounting means for mounting said valve on said adapter body to selectively control flow of fluid between said central bore and said side bore. 27. A fluid control system for raising and lowering a chair using pressurized fluid, said system comprising a self-actuating fluid flow rate control valve comprising a chamber defined by a chamber wall with a fluid inlet opening at one region of the chamber and a fluid outlet port extending through the chamber wall spaced from the inlet opening, a valve member located for movement in the chamber between the inlet opening and port, said valve member having a head portion facing in the direction of said inlet opening to be acted upon by fluid pressure to urge the valve member to move from a first position spaced from the port toward a second position adjacent the port to inhibit outflow of fluid from the chamber through the port, and biasing mechanism operable to yieldably urge the valve member toward its first position. 28. The system of claim 27, wherein the head portion of said valve member has an orifice extending therethrough of a selected opening size to produce a selected rate of fluid flow. 29. The system of claim 28, wherein said control valve further comprises an elongate cylindrical sleeve defining said chamber wall, said inlet opening is provided adjacent one end of said sleeve, and said valve member is located for sliding movement axially within said sleeve. 30. The system of claim 29, wherein the end of the sleeve opposite said one end is closed, and said outlet port is positioned between said one end and said opposite end. 31. The system of claim 29, which further comprises a stop for limiting the movement of said valve member in the direction of said inlet opening. 32. A fluid control system for raising and lowering a chair using pressurized fluid, said system comprising a cushion valve comprising a valve chamber defined by a chamber wall, a fluid pressure inlet adjacent one portion of said chamber, a fluid outlet port extending through said chamber wall in a region spaced from said inlet region and a valve assembly located in said chamber for movement between a first position adjacent said port to inhibit flow of fluid from said chamber through said port, and a second position permitting substantially free flow of fluid from said chamber through said port, and biasing mechanism urging said valve assembly toward said first position and yieldable to permit movement of said valve assembly to said second position upon a pressure above a selected pressure being exerted by fluid from said fluid inlet region on said valve assembly. 33. The system of claim 32, wherein said cushion valve assembly comprises a valve body having a sidewall configuration substantially complementary to the chamber wall configuration to permit sliding movement of the valve body within the chamber, a substantially closed head portion at one end of the valve body facing in the direction of said inlet region, an internal bore opening toward the opposite end of said valve body from said inlet region, a fluid flow control orifice formed adjacent said head portion permitting controlled flow of fluid into said internal bore, and a normally-closed check valve mounted in said internal bore which is urged to an open position to permit fluid flow through said orifice to said opposite end of said valve assembly. 34. The system of claim of claim 32, wherein said chamber has a closed end spaced from said inlet portion, and said fluid outlet port is positioned between said inlet portion and said closed end, and said valve assembly comprises a valve member having an outer configuration substantially complementary to an internal surface of said chamber wall and received in said chamber in close sliding contact with said chamber wall, and a retaining space defined between said valve member and said closed end of said chamber capable of retaining a quantity of impeding fluid to impede movement of said valve member to said second position, said valve member being mated to said cham ber wall such that a quantity of impeding fluid may be expressed slowly from said retaining space to said port to allow the valve member to move slowly toward said second position. 35. The system of claim 34, wherein said valve assembly further comprises a fluid flow orifice extending through a portion of the valve member directed toward said inlet portion, and a check valve permitting fluid flow from said orifice to said retaining space and inhibiting fluid flow in a reverse direction. 36. The system of claim 32, wherein said cushion valve assembly comprises a valve body having a substantially impermeable sidewall configuration substantially complementary to the chamber wall configuration to permit sliding movement of the valve body within the chamber, a substantially closed head portion at one end of the valve body facing in the direction of said inlet region, an internal bore opening toward the opposite end of said valve body from said inlet region, a fluid flow control orifice formed adjacent said head portion permitting controlled flow of fluid into said bore, and a normally-closed check valve mounted in said bore which is urged to an open position to permit fluid flow through said orifice to said opposite side of said valve assembly. 37. A control system for a chair comprisinga fluid pressure operated chair actuator,a reservoir for holding fluid,a pump,a fluid flow circuit operatively connecting said pump to said reservoir and actuator allowing the pump to draw fluid from the reservoir and to supply fluid under pressure to said chair actuator and for returning fluid from the actuator to the reservoir, said fluid flow circuit comprising a selectively operable valve to control return of fluid from the actuator to said reservoir, a fluid pressure accumulator connected in said circuit between said pump and chair actuator and between said chair actuator and said selectively operable valve to provide accumulator action upon supply of fluid under pressure to said chair actuator and upon return of fluid from the actuator to the reservoir, and a flow rate control valve connected in said circuit between the chair actuator and the accumulator. 38. The control system of claim 37, wherein said flow circuit comprises a fluid return circuit through which fluid is returned from said actuator to the reservoir and said accumulator and flow rate control valve are positioned in said fluid return circuit with said flow rate control valve disposed between said actuator and said accumulator. 39. The control system of claim 38, wherein said selectively operable valve is positioned in said fluid return circuit. 40. The control system of claim 38, wherein said fluid return circuit further comprises a cushion valve assembly disposed between said accumulator and the reservoir. 41. The control system of claim 40, wherein said cushion valve assembly comprises a valve chamber defined by a chamber wall, a fluid pressure inlet region adjacent one portion of said chamber, a fluid outlet port extending through said chamber wall in a region spaced from said inlet region, and a valve assembly comprising a plunger mounted in said chamber for movement between a first position adjacent said port to inhibit flow of fluid from said chamber through said port, and a second position permitting less inhibited flow of fluid from said chamber through said port, and biasing mechanism urging said plunger toward said first position and yieldable to permit movement of said plunger to said second position upon a pressure above a selected pressure being exerted from said fluid inlet region on said plunger assembly. 42. The control system of claim 37, wherein said fluid flow circuit comprises a fluid supply circuit through which fluid is provided from said motor to said chair actuator and said accumulator and flow rate control valve are positioned in said fluid supply circuit with said flow rate control valve disposed between said accumulator and said chair actuator. 43. A c ontrol system for a chair comprisinga fluid pressure operated chair actuator,a reservoir for holding fluid,a pump,a fluid flow circuit operatively connecting said pump to said reservoir and actuator allowing the pump to draw fluid from the reservoir and to supply fluid under pressure to said chair actuator and for returning fluid from the actuator to the reservoir, said fluid flow circuit comprising a selectively operable valve to control return of fluid from the actuator to said reservoir, a fluid pressure accumulator connected in said circuit between said pump and chair actuator and between said chair actuator and said selectively operable valve, and a flow rate control valve connected in said circuit between the chair actuator and the accumulator, wherein said accumulator comprises an elongate cylinder chamber, a pressure fluid inlet at one portion of said chamber, a piston sealingly mounted in said chamber for sliding movement axially of the chamber, with one face of the piston directed toward said pressure fluid inlet and an apposite face directed away from the pressure fluid inlet, biasing mechanism yieldably urging said piston in the direction of said fluid inlet, and a low pressure fluid outlet from the chamber on the side of the piston toward which said opposite face is directed. 44. The system of claim 43, wherein said low pressure fluid outlet comprises a restricted outlet orifice of selected size to control the flow of fluid from the chamber. 45. The system of claim 43, wherein said accumulator further comprises a pressure relief valve extending through said piston operable to release excess pressure from the pressure inlet side of said piston to the low pressure outlet side of the piston. 46. The system of claim 45, wherein said pressure relief valve comprises a bore extending through said piston from said one face to said opposite face, a valve member mounted for shifting between a first position closing said bore to fluid flow therethrough and a second position permitting fluid flow therethrough, and biasing mechanism urging said valve member toward said first position, said biasing mechanism being yieldable to permit movement of said valve member to its second position upon a pre-selected pressure being exerted against said valve member by fluid on the inlet side of said piston. 47. The system of claim 45, wherein said biasing mechanism comprises a spring. 48. A control system for a chair comprisinga fluid pressure operated chair actuator,a reservoir for holding fluid,a pump,a fluid flow circuit operatively connecting said pump to said reservoir and actuator allowing the pump to draw fluid from the reservoir and to supply fluid under pressure to said chair actuator and for returning fluid from the actuator to the reservoir, said fluid flow circuit comprising a selectively operable valve to control return of fluid from the actuator to said reservoir, a fluid pressure accumulator connected in said circuit between said pump and chair actuator and between said chair actuator and said selectively operable valve, and a flow rate control valve connected in said circuit between the chair actuator and the accumulator, wherein fluid returns from said chair actuator under pressure and said flow rate control valve comprises a self-actuating valve comprising a chamber defined by a chamber wall with a fluid inlet opening at one region of the chamber and a fluid outlet port extending through the chamber wall spaced from the inlet opening, a plunger mounted for movement in the chamber between the inlet opening and port, said plunger having a head portion facing in the direction of said inlet opening to be acted upon by fluid pressure to urge the plunger to move from a first position spaced from the port toward a second position adjacent the port to inhibit outflow of fluid from the chamber through the port, and biasing mechanism urging the plunger toward its first position. 49. The system of claim 48, wherein said plunger is m ovable to multiple different positions between said first and second positions adjacent the port to produce variation in fluid outflow responsive to fluid inlet pressures. 50. The system of claim 48, wherein the head portion of said plunger has an orifice extending therethrough of a selected opening size to produce a selected rate of fluid flow. 51. The system of claim 50, wherein said flow rate control valve further comprises an elongate hollow cylindrical sleeve defining said chamber wall, said inlet opening is provided adjacent one end of said sleeve, and said plunger is mounted for sliding movement axially within said sleeve. 52. The system of claim 51, wherein the end of the sleeve opposite said one end is closed, and said port is positioned between said one end and said opposite end. 53. The system of claim 51, which further comprises a stop for limiting the movement of said plunger in the direction of said inlet opening. 54. The system of claim 50, wherein said sleeve is substantially closed other than for said inlet opening and said port. 55. The system of claim 54, wherein said inlet opening is defined at one end of said sleeve, the opposite end of said sleeve is closed, and said biasing mechanism comprises a spring interposed between said closed end of the sleeve and said plunger. 56. A control system for a chair comprisinga fluid pressure operated chair actuator,a reservoir for holding fluid,a pump,a fluid flow circuit operatively connecting said pump to said reservoir and actuator allowing the pump to draw fluid from the reservoir and to supply fluid under pressure to said chair actuator and for returning fluid from the actuator to the reservoir, said fluid flow circuit comprising a selectively operable valve to control return of fluid from the actuator to said reservoir, a fluid pressure accumulator connected in said circuit between said pump and chair actuator and between said chair actuator and said selectively operable valve, and a flow rate control valve connected in said circuit between the chair actuator and the accumulator, wherein said fluid flow circuit further comprises a cushion valve assembly. 57. The system of claim 56, wherein said cushion valve assembly comprises a valve chamber defined by a chamber wall, a fluid pressure inlet region adjacent one portion of said chamber, a fluid outlet port extending through said chamber wall in a region spaced from said inlet region, and a valve assembly comprising a plunger mounted in said chamber for movement between a first position adjacent said port to inhibit flow of fluid from said chamber through said port, and a second position permitting less inhibited flow of fluid from said chamber through said port, and biasing mechanism urging said plunger toward said first position and yieldable to permit movement of said plunger said second position upon a pressure above a selected pressure being exerted from said fluid inlet region on said plunger assembly. 58. The system of claim 57, wherein said plunger is movable to multiple different positions between said first and second positions. 59. The system of claim 57, wherein said plunger comprises a plunger body having a substantially impermeable sidewall configuration substantially complementary to the chamber wall configuration to permit sliding movement of the plunger body within the chamber, a substantially closed head portion at one end of the plunger body facing in the direction of said inlet region, an internal bore opening toward the end of said plunger body opposite said inlet region, a fluid flow control orifice formed adjacent said head portion permitting controlled flow of fluid into said internal bore, and a normally-closed check valve mounted in said internal bore which is urged to an open position to permit fluid to flow through said orifice to said opposite end of said plunger body. 60. The system of claim of claim 57, wherein said valve chamber has a closed end spaced from said inlet portion, said f luid outlet port is positioned between said inlet portion and said closed end, and said plunger has an outer configuration substantially complementary to an internal surface of said chamber wall and is received in said chamber in close sliding contact with said chamber wall, and a retaining space defined between said plunger and said closed end of said chamber capable of retaining a quantity of impeding fluid to impede movement of said plunger to said second position, said plunger being mated to said chamber wall such that a quantity of impeding fluid may be expressed slowly from said retaining space to said port to allow the plunger to move slowly toward said second position. 61. The system of claim 60, wherein said valve assembly further comprises a fluid flow orifice extending through a portion of the plunger directed toward said inlet portion, and a check valve permitting fluid flow from said orifice to said retaining space and inhibiting fluid flow in a reverse direction. 62. A control system for a chair comprisinga first fluid pressure operated chair actuator,a second fluid pressure operated chair actuator,a reservoir for holding fluid,a bi-directional pump,a first fluid flow circuit operatively connecting said pump to said reservoir and to said first chair actuator allowing the pump when operated in one direction to draw fluid from the reservoir and to supply fluid under pressure to said first chair actuator and for returning fluid from the first chair actuator to the reservoir, said first fluid flow circuit comprising a first selectively operable valve to control return of fluid from the actuator to said reservoir, a first fluid pressure accumulator connected in said first circuit between said pump and first chair actuator and between said first chair actuator and said first selectively operable valve to provide accumulator action upon supply of fluid under pressure to said chair actuator and upon return of fluid from the actuator to the reservoir, and a first flow rate control valve connected in said first circuit between said first chair actuator and said first accumulator, anda second fluid flow circuit operatively connecting said pump to said reservoir and to said second chair actuator allowing the pump when operated in a direction opposite said one direction to draw fluid from the reservoir and to supply fluid under pressure to said second chair actuator and for returning fluid from the second chair actuator to the reservoir, said second fluid flow circuit comprising a second selectively operable valve to control return of fluid from the second chair actuator to said reservoir, a second fluid pressure accumulator connected in said second circuit between said pump and second chair actuator and between said second chair actuator and said second selectively operable valve to provide accumulator action upon supply of fluid under pressure to said chair actuator and upon return of fluid from the actuator to the reservoir, and a second flow rate control valve connected in said second circuit between said second chair actuator and said second accumulator. 63. A control system for a chair comprisinga first fluid pressure operated chair actuator,a second fluid pressure operated chair actuator,a reservoir for holding fluid,a bi-directional pump,a first fluid flow circuit operatively connecting said pump to said reservoir and to said first chair actuator allowing the pump when operated in one direction to draw fluid from the reservoir and to supply fluid under pressure to said first chair actuator and for returning fluid from the first chair actuator to the reservoir, said first fluid flow circuit comprising a first selectively operable valve to control return of fluid from the actuator to said reservoir, a first fluid pressure accumulator connected in said first circuit between said pump and first chair actuator and between said first chair actuator and said first selectively operable valve, and a first flow rate control val ve connected in said first circuit between said first chair actuator and said first accumulator, anda second fluid flow circuit operatively connecting said pump to said reservoir and to said second chair actuator allowing the pump when operated in a direction opposite said one direction to draw fluid from the reservoir and to supply fluid under pressure to said second chair actuator and for returning fluid from the second chair actuator to the reservoir, said second fluid flow circuit comprising a second selectively operable valve to control return of fluid from the second chair actuator to said reservoir, a second fluid pressure accumulator connected in said second circuit between said pump and second chair actuator and between said second chair actuator and said second selectively operable valve, and a second flow rate control valve connected in said second circuit between said second chair actuator and said second accumulator, wherein said first fluid flow circuit comprises a first cushion valve and said second fluid flow circuit comprises a second cushion valve. 64. The system of claim 62, wherein said first and second fluid flow circuits comprise check valves which inhibit flow of fluid under pressure from said pump to said second chair actuator when the pump is operated in said one direction and inhibit flow of fluid under pressure from said pump to said first chair actuator when said pump is operated in said opposite direction.