Abstract: In machines such as hauling units having electro-hydraulic transmission controls, it is desirable to ensure that in the event of an electrical malfunction or power failure the transmission remains in one of its gear ratios. In the subject invention, a dependent latching system is provided in a transmission which in the event of an electrical malfunction latches the transmission in the existing gear ratio or a gear ratio within at least two gears ratios. This is accomplished by providing a master latch valve mechanism, a logic valve arrangement, and a latching shuttle valve to act in cooperation with an electrically controlled proportional valve and a hydraulic proportional valve that controls engagement of a plurality of hydraulically actuated clutches. The master latch valve mechanism directs pressurized fluid from a source of pressurized fluid through the logic valve to urge the latching shuttle valve to an open position.

Abstract: Inching valves for providing controlled slow movement of a vehicle normally have a valve mechanism therein to control the pressure level of the fluid being directed to the driving clutch of the vehicle. Upon release of the pedal, a sudden jerk of the vehicle may occur. The modulating inching valve of the subject arrangement provides a housing having a valving mechanism slidably disposed therein and operative to selectively block communication between an inlet port and an outlet port. The modulating inching valve further includes an input actuator mechanism operative to selectively control the valve mechanism in response to the position of the operator's inching pedal. Through a portion of a predetermined travel distance of the input mechanism the operator controls the rate of pressure being supplied to the fluid actuated device and during the remaining portion of the predetermined travel distance the modulating relief valve automatically controls the rate of pressure rise.

Abstract: The present cooling system provides a limited flow rate to the clutches during disengagement and provides additional cooling flow to the clutches during partial engagement and controls the pressure level of the fluid from the source of cooling fluid by operation of a valve mechanism which is responsive to a control mechanism. Upon full engagement, the valve mechanism automatically reduces the volume of cooling fluid to the clutches and simultaneously reduces the pressure level of the cooling flow from the source of cooling fluid. This cooling system provides the needed volume of cooling fluid during partial engagement of the clutches and also reduces the volume of cooling fluid during disengagement to reduce drag forces while further reducing the volume of cooling fluid during full engagement to conserve horsepower.

Abstract: A control system (10) for a spring applied, pressure released brake (16) is provided to control the pressure level in the brake (16) in response to operation of a control valve (22) to stage the pressure levels relative to the operating mode of the control valve. The control system (10) also provides two different fluid pathways (58,60) that are individually operational to lubricate a winch and draw-works mechanism (18) in response to the operating position of the control valve (22). This system improves the response time needed to gradually release the brake (18).

Abstract: This invention relates to a brake control system (10) for controlling engagement and disengagement of a spring applied pressure released brake (11) of a winch and includes an orifice (39) and a relief valve (37) connected in series to the outlet port of a metering pump (23) to relieve pressure in the outlet port at a lower than normal pressure level when the fluid flow therethrough is below a predetermined flow rate. Relieving the pressure at the outlet port of the metering pump reduces the pressure differential between the inlet port (24) and outlet port (26) of the metering pump and thereby drastically reduces the internal leakage within the metering pump so that the metering pump is operative to pump fluid from the actuating chamber (14) at the slow rotational speeds of the rotatable member (12).

Abstract: A hydraulic latching valve mechanism (48) is provided integral with a control valve (14) to hydraulically hold an actuator (47) in an engaged position (E). This eliminates the need for mechanical detents and/or extra external lines. The valve mechanism (48) has first and second members (58, 66) which cooperate to selectively communicate a fluid chamber (59) with an exhaust port (52) or an inlet port (26) in response to the actuator (47) being moved from a first position (D) to the second position (E). This arrangement is used to maintain a valve spool (30) in a second position for extended periods of time by using the system pressure as the holding force.

Abstract: A selector valve (10) for providing a plurality of fluid signals has a plurality of signal ports (17-22) and a pair of drain ports (23,24) opening into a bore (14) of a body (11) and are angularly spaced one from another in a plane normal to the axis of the bore (14). A spool (12) is reciprocatable within the bore (14) between a plurality of positions. At each position at least one of a plurality of radial passages (48-57) in the spool (12) communicates an inlet passage (25) with a manifold (41), another of the radial passages communicates the manifold (41) with one of the signal ports (17-22) and one or more of a plurality of arcuate pockets (60-68) in the spool (12) communicate the other signal ports (17-22) with the drain ports (23,24).

Abstract: PCT No. PCT/US79/00293 Sec. 371 Date May 2, 1979 Sec. 102(e) Date May 2, 1979 PCT Filed May 2, 1979 PCT Pub. No. WO80/02446 PCT Pub. Date Nov. 13, 1980.In a control (28) for a hydraulically operated draw works or the like having a hydraulically disengaged brake (14), a transmission (10, 12) and a brake control valve (114, 122), the improvement including an accumulator (174) having a check valve (196) connected between the brake control valve outlet (152) and the brake (14) to modulate the application of the brake (14) after the brake (14) has been fully released and to provide no modulation of brake (14) application after the brake (14) has been only partially released to thereby minimize shock in the draw works components when a load is lowered rapidly and yet provide rapid action when operated slowly.

Abstract: A control for a hydraulically operated winch or the like having a hydraulically disengaged brake, a multi-speed, hydraulically controlled transmission, and a drum to be driven or braked. The control system includes means whereby the transmission is placed in neutral, automatically, whenever the brake is to be disengaged to lower a load and a control valve including a spool with small and large slots along with a drum-driven metering pump controls fast and slow lowering speeds. Emergency free fall of the load is accomplished in the valve by bypassing the small metering slot. An arrangement of an accumulator and check valves allow hydraulic disengagement of the brake even if the engine is dead and there is provided a recirculating hydraulic circuit to conserve oil in such an instance so that the accumulator volume can be minimized.

Abstract: A control valve pressurizes an outlet conduit when a variable fluid pressure signal rises above a first predetermined level and depressurizes the outlet conduit when the variable signal subsequently drops below a second level that is lower than the first level, the valve further functioning to maintain the outlet conduit unpressurized without regard to the variable fluid pressure signal level in the absence of a second fluid pressure signal. The control valve automatically controls a fluid pressure operated lock-up clutch of a torque converter in a vehicle transmission system. The variable fluid pressure signal source may be a governor producing a pressure proportional to vehicle speed while the second fluid pressure signal source is one or more of the transmission drive conditioning devices.

Abstract: A check valve comprises a spring biased poppet reciprocally mounted in a housing thereof to normally close an inlet to the valve. A set screw is threadably mounted in an exposed position on the housing to selectively vary the spring load on the poppet to thus vary the pressure setting thereof. An annular elastomeric locking member circumvents the set screw and is compressed radially inwardly thereagainst by a clamping member, releasably attached on the housing, to retain the set screw in its preset position.