Abstract: The invention provides an improved manifold assembly and hydraulic system for use in connecting hydraulic lines according to a predetermined circuit design. The invention is especially useful in a pilot control circuit for operating heavy equipment that is multifunctional or has the ability to operate multiple attachments. The manifold assembly comprises a baseplate having a plurality of inlet and outlet ports that are connected to various components in the hydraulic circuit. Connecting elements are then used to connect the designated inlet and outlet ports. In a preferred embodiment, the connecting elements include one or more channel plates attached to the baseplate that have segregated flow channels or passageways and interconnect the designated inlet and outlet ports. In order to convert the system from operation of one type of attachment to another, it is only necessary to exchange one set of designated channel plates for another.

Abstract: A control system for the boom and bucket operation system on a front end loader that includes an unloader valve responsive to pilot valve pressure to bypass hydraulic fluid pumped by an auxiliary pump to the reservoir while maintaining the primary pump supply to a loader valve which supplies pressure to the boom and bucket cylinders in response to the operation of pilot valves. The unloader valve bypasses the auxiliary pump flow when the pressure is below a predetermined value and when the pressure is above a second higher predetermined value.

Abstract: A hydraulic circuit for pitch and tilt control of a dozer blade attached to push arms on a vehicle with a pitch ram connected between one push arm and the blade and a dual actuator consisting of a second pitch ram and a tilt ram connected at their head ends. A pitch valve directs hydraulic fluid to and from the pitch rams with a diverter/combiner valve interposed therebetween to assure a flow of fluid either to said rams or from said rams at equal rates. Pilot-operated check valves hydraulically lock the pitch rams until opened by pressure directed from said pitch valve. Tilt and lift valves directs fluid pressure to and from the tilt ram and a lift ram respectively with regeneration capability for both tilt and lift functions.

Abstract: A control means for a variable displacement pump (12) driven by an engine (10) and having a servo-cylinder (78) determining the displacement of the variable pump (12). A charge pump (14) is driven by the engine (10) and supplies charge pressure to the variable pump (12) through an orifice (40). Pilot conduits (42,44) on each side of the orifice (40) sense the pressure drop due to flow and relay the resulting signals to each end of a metering spool (52) in a speed control valve (46), which is arranged to control the pressure in the servo-cylinder (78). A spring (90) biases the servo-cylinder (78) toward an extreme position for the variable pump (12) and opposes the pressure directed to the servo-cylinder (78) by the speed valve (46) in order to provide a smooth transition between the extreme positions for pump displacement.

Abstract: A variable speed engine (10) drives a tractive effort drive train (12) and fixed and variable displacement pumps, (14 and 16) arranged to supply fluid pressure to a hydraulic work system (24). The displacement of the variable pump (16) is determined by a control ram (42) and a conduit (44, 53, 74) interconnects the variable pump output and the control ram (42). An engine speed control valve (60) and a system pressure compensator valve (46) interposed in series in said conduit (44, 53, 74). The two valves (60 and 46) maintain the variable pump (16) at full output except when low engine speed and high system pressure exists simultaneously.

Abstract: A hydraulic system for a vehicle having an engine (10) governed to run within a predetermined speed range; the engine (10) arranged to drive a motive power train (11), a charge pump (14), a variable displacement pump (12) and a fixed displacement pump (15). The variable and fixed pumps (12 and 15) are arranged to supply hydraulic fluid pressure to a work circuit (26). A flow signal is created by passing the output from the charge pump (14) through an orifice (40), which signal is routed to a speed valve (46) which directs fluid to a control ram (78) to reduce the displacement of the pump (15) during a predetermined intermediate portion of said speed range.