Abstract: A control mechanism for the lift cylinder of an electric lift truck. A first pump motor is energized by the closing of a first switch in response to movement of the lift valve spool toward the lift position. A second pump motor is energized when the lift valve spool is in its full lift position and a bending moment is applied to the control rod controlling the lift valve spool of sufficient magnitude to elastically deflect the control rod into closing engagement with the switch.

Abstract: A hydraulic pump unloading system having an engine driving two hydraulic pumps which are connected in parallel to a load-supporting member. An unloading valve is connected in the hydraulic line with one of the two pumps and is shiftable between positions for directing flow to the load and for directing flow to a reservoir, depending upon the pressure and or flow in the hydraulic line. Also, a pressure-compensated flow-control valve is connected in the line with the other pump and, under certain conditions, directs fluid pressure to the unloading valve for setting the unloading valve in either the operative or the unloading position, all depending upon the hydraulic condition at the load-supporting member. Further, either an additional valve or a spring can be effective on the unloading valve for controlling the operative and the unloading position of the unloading valve.

Abstract: A loader vehicle includes a loading implement movable to a dump and a rack-back position by means of actuation of cylinders. The movement of the cylinders is provided by fluid control valves in turn operated by means which provide for both a slow dump and a fast dump movement of the implement, with fast dump movement initially selected being automatically changed to slow dump movement dependent on the position of the implement.

Abstract: A vehicle includes first and second drive transmission assemblies, each having a control element and associated control valve for selectively establishing forward and reverse operation thereof. A control system therefore includes a plurality of master and slave cylinders for individually moving the control elements, a first manual control for operating the transmission assemblies at substantially the same speed and direction, and a second manual control for controllably altering or overriding the first manual control for steering purposes.

Abstract: A manually operable hydraulic actuator which utilizes a main pump and an auxiliary pump to quickly develop a relatively large useful hydraulic force, for example, in applying compression accessories to stranded conductors such as cables. The main pump develops a relatively high pressure from a low volume of hydraulic fluid to develop the primary hydraulic force. The auxiliary pump develops a relatively low pressure from a high volume of hydraulic fluid to produce rapid advancement of a force-applying piston relative to a work piece. Both the main and auxiliary pumps are operated by the opposed swinging movement of two manually operable handles. One of the handles is selectively movable between a first position for simultaneously actuating both the main and auxiliary pumps and a second position for actuating the main pump only. A pressure relief system is provided to ensure development of the maximum rated pressure of the force-applying piston before retraction thereof can be effected.

Abstract: An automatic change-speed transmission for vehicles with a drive connection between a transmission output shaft adapted to be coupled with vehicle wheels and a secondary servo-force generator for the emergency supply of aggregates of the transmission control and shifting system operating with a servo-pressure, which drive connection is adapted to be disconnected by a disengaging mechanism, and with a permanent drive connection between a transmission input shaft adapted to be driven by a driving engine and a primary servo-force generator for the normal supply of the aggregates; a servo-motor for the disengaging mechanism which is adapted to be displaced into a disengaging position disconnecting the secondary servo-force generator from the transmission output shaft is brought into its working position by a control device operating in dependence on the servo-force of the primary servo-force generator when the actual value of the servo-force lies below a necessary operating value.

Abstract: A hydraulic system including a pressure and flow compensated pump, a source of pilot fluid under pressure, a plurality of hydraulic circuits each including a work performing device, a plurality of controls, one for each circuit, each including a pilot operated flow valve for connecting the associated work performing device to the pump and an operator positioned valve connected to the pilot source for selectively directing pilot fluid to the corresponding flow valve, the work performing devices and the flow valves being connected in parallel.

Abstract: A reversible power transmission for transmitting input power supplied from either direction. The transmission comprises in combination a plurality of fluid power units for driving or receiving power from a first plurality of fluid actuators. The first plurality of fluid actuators are timed together for cooperating in a mutually complementary manner to substantially linearize a normally pulsating power transfer. The first plurality of actuators may be connected to additional actuators for providing or receiving rotary motion or to plungers operating within stuffing boxes for constant flow pumping or fluid power transfer.

Abstract: A first control valve of a fluid circuit connecting a first pump to a fluid motor has a signal port in communication with an inlet port when the first control valve is at a selected position at which substantially the total output of the first pump is directed to the motor. A valve device connects a second pump to the fluid circuit in response to a valve spool of the first control valve being moved to said selected position. The valve device has a valve member movable between a first position at which the second pump is in communication with a tank and a second position at which the output of the second pump is combined with the output of the first pump in the fluid circuit. A device moves the valve member to the second position in response to the valve spool of the first control valve being moved to said selected position. The device includes first and second actuation devices associated with the first and second ends of the valve member.

Abstract: A hydraulically operated driving and controlling unit includes a power plant--(prime mover)--with a fluid flow producing means for the supply of at least one pair of hydraulic flows of equal rate of flow. One separated fluid line is exclusively communicated to one outlet of the flow producing means and to one hydraulic motor. A further separated fluid line is exclusively communicated to another outlet of the flow producing means and to another hydraulic motor. The motors carry fluid stream creation means like propellers. The said flows flow through said fluid lines to drive the said motors and fluid stream creation means at all times with, relative to each other, equal rotary velocities for the creation of equal thrusts by said fluid stream creation means. The flow supply device may be variable for proportionate variation of the said rotary velocities and thrusts. In addition a further control means is provided for governing variation of rotary velocities and thrusts relative to each other.

Abstract: In a crawler having a rear housing or frame a pair of hydrostatic transmission pumps are mounted back-to-back and interconnected by a manifold which acts as a mounting for the pumps on to the rear housing. One pump is located within the rear housing and the other pump is outside.

Abstract: A pressure control valve is connected to selectively supply a control pressure signal to shift a relief valve from a first low pressure mode to a second higher pressure mode and for simultaneously supplying the control pressure signal to an associated variable displacement pump for reducing the relatively high output of the pump to a relatively lower output.

Abstract: A vehicle has elements providing a fluid pathway to the controlling system of spring actuated, normally locked brakes that are fluid releasable. The elements forming the fluid pathway are connectable to a fluid power assembly that is movable to and from the vehicle and releasably connected to the fluid pathway.

Abstract: A fluid circuit connects a first pump to a first motor and has a control valve for controlling fluid flow to the first motor. The control valve is movable between a first position at which the first pump is blocked from communication with the first motor, a second position at which fluid flow to the motor is controllably modulated and a third position at which substantially the full output of the first pump is directed to the first motor. A valve device connects a second pump to the fluid circuit and is movable between a first position at which the second pump is in communication with a tank and a second position at which the output of the second pump is combined with the output of the first pump. The valve device is moved to the second position in response to the control valve being moved from said second position toward said third position.

Abstract: A fluid control system for a mobile aerial tower which includes a plurality of positioning elements such as first and second interconnected booms and a turntable for rotating the booms about a vertical axis. The control system comprises first and second variable speed pumps and a bank of three double acting valves operatively connected between the pumps and the positioning elements so as to control the direction of fluid flow thereto, and a pneumatically linked remote control system for selectively controlling the speeds at which the pumps operate and for selectively operating the valves to direct fluid between either of the pumps and any one of the positioning elements, or alternatively between both of the pumps respectively and any two of the positioning elements, or alternatively between the pumps collectively and any one of the positioning elements.

Abstract: A fluid system has at least first and second circuits each having a plurality of work elements connected in interruptible series. Control elements are provided for selectively, automatically passing fluid from one circuit to preselected positions in the other circuit in response to operation of preselected work elements.

Abstract: A method and apparatus are disclosed for mechanically steering vehicles such as crawler tractors and the like or skid steer tractors, which include a pair of independently operable power sources. The apparatus includes a pair of independent first linkage systems interconnected between a single operator control lever and each respective power source to achieve equivalent power outputs from the sources upon movement of the lever. A pair of independent second linkage systems are interconnected between respective links in the first linkage system and respective throttling means. In the method, each throttling means may be operated independently of the other to achieve unequal power outputs from the two sources by virtue of the independent first and second linkage systems.

Abstract: Hydraulic brake and clutch apparatus includes a master cylinder for applying pressure to a brake past a sequence valve, such pressure also being applied to move another valve against a spring from a position wherein a pump applies fluid pressure to engage a transmission, to a position wherein fluid pressure is dumped from the transmission to provide disengagement thereof.

Abstract: A fluid drive assembly has a pump, a variable displacement motor, a fluid circuit connecting the pump to the motor, and an actuator device for controlling the displacement of the motor. The actuator device is movable between a first position at which the displacement of the motor is at a preselected maximum and a second position at which the displacement of the motor is at a preselected minimum. A control system for the fluid drive assembly includes a source of fluid at a first preselected pressure value. A valve device is connected to the source of fluid and to the actuator device for controlling the fluid flow therebetween and is movable between a first position at which the source of fluid is in communication with the actuator device and a second position at which the source of fluid is blocked from communication with the actuator device.

Abstract: A hydraulic power circuit for operating hydraulic motors at several speeds includes first and second fluid sources and a valve assembly for combining flow from the second source with flow from the first source as a faster motor speed is required. The valve assembly includes a first valve controlling the flow of fluid from the first source to the motors while a slow motor speed is required. The valve assembly also includes a fluid actuated valve controlling the flow of fluid from the second source to the motors as a faster motor speed is required. The fluid actuated valve is actuated by flow from the first source through metering ducts. Once the fluid actuated valve is actuated, fluid from the second source is mixed with fluid from the first source and the valve assembly communicates the increased flow to the motors thus obtaining a faster motor speed.

Abstract: A control system for plural circuits having motor-driven hydraulic pumps. As disclosed, a pair of pumps is connected in a hydraulic actuating circuit individual to that pair and the circuit includes an hydraulically operated actuator to be advanced and retracted by fluid under pressure delivered from the pair of pumps of that circuit. A single prime mover drives the pair of pumps and pumps in other circuits, and each circuit has a pressure-responsive control valve which provides for unloading a pump of the first circuit in response to increases in pressure in the various other circuits to a predetermined value at which, in the absence of such unloading, the input horsepower requirement has risen toward a value which would stall the prime mover.Pumps in several of the circuits may be sequentially and selectively unloaded.

Abstract: The invention is concerned with an improvement in a hydraulic fluid system of a vehicle which comprises a variable displacement pump; a first work element; and a device for receiving a first load signal from the first work element and controlling the pump discharge responsive thereto. The improvement includes a plurality of second work elements which receive fluid flow from the pump via a common supply line connected to the first work element, said fluid flow not passing via any independent load responsive delivery system, and a load responsive controller having flow restricting means in a signal line which communicates with the common supply line for sensing a load pressure in the common supply line, said load pressure being a maximum load pressure of any of the second work elements and delivering a second load signal representative of the load pressure to combine with the first load signal to control the discharge of the pump to be responsive to the larger of the first and second load signals.

Abstract: A hydraulic drive circuit for tracked vehicles is provided in the form of two hydrostatic transmissions, one for each track with a control system for one track acting as a master control and the other transmission control following as a slave unit, except as modified by the signal from a manual steering control.

Abstract: A hydraulically driving and controlling - unit comprises a power plant which drives a fluid flow producing device for the separate production and supply of pairs of flows of hydraulic fluid under pressure. The unit supplies at least one pair of flows to at least two fluid motors. Rates of flow in flows are proportionate to each other whereby motors of same pair of flow are actuated and maintained to act with to each other proportionate speed of motion. Unit may be transportable and adaptable to machines or vehicles. The drive unit may include a plurality of power plants and fluid flow producing devices. In such multiple unit one way valves are set into fluid lines which may combine partially after those one way valves for directing each one flow from a different power plant to the same motor. Thereby the unit can continue to operate, when one of the plurality of power plants fails.

Abstract: An actuator system for a dual path transmission usable with a vehicle, such as a crawler tractor or the like, wherein a pair of hydrostatic transmission units each have at least one power unit with variable displacement means therefor responsive to a control pressure for setting displacement, a control console mountable on the vehicle has a plurality of control valves including a ratio valve for setting a control pressure to establish the direction and speed of travel of the vehicle by uniform speed of both transmission units, and steer valves which may modify the speed of at least one transmission unit for steering of the vehicle, and a control station including a manually operable control member remote from the control console with motion-transmitting linkages whereby movement of the control member in one path may cause adjustment of the ratio valve for establishing the speed and direction of travel of the vehicle either forward or reverse and with movement of the control lever along an intersecting path ca

Abstract: Hydrostatic energy is converted to kinetic energy preferably for generating electricity by driving a fluid actuated motor connected to an electrical generator. Pumps are arranged in parallel for driving the motor, and are in turn actuated by engines driven themselves by a liquid contained in a reservoir in which the engines are disposed. The liquid in the reservoir is transferred to and from and also between the engines for actuating same.

Abstract: A hydrostatic drive system for connecting a prime mover and a hydraulically operable load such as a hydraulic motor connected to the vehicular wheel has a constant-displacement pump and a variable-displacement pump both connected to the prime mover. The variable-displacement pump is completely reversible and is of maximum displacement substantially greater than the constant displacement pump. This variable-displacement pump is permanently connected across the hydraulic motor of the load. A clutch connects the constant-displacement pump to the same shaft as the variable-displacement pump. The outputs of the constant-displacement pump may be connected by a valve either in parallel to the outputs of the variable-displacement pump, or may simply connect them together for operation of the load only by the variable-displacement pump.

Abstract: A fluid system has a plurality of pumps, left and right track motors and a plurality of work elements. First elements are provided for controllably delivering fluid from a first plurality of pumps to the left track motor and for controllably bypassing the left track motor and delivering fluid from at least one of the first plurality of pumps to a separate respective work element. Second elements are provided for controllably delivering fluid from a different plurality of said pumps to the right track motor and for controllably bypassing the right track motor and delivering fluid from at least one of the second plurality of pumps to a separate respective work element.

Abstract: A pressure system for driving the wheels of a vehicle in which the wheel driving motors are arranged in pairs on opposite sides of the vehicle comprising a duplex pump assembly composed of two pumps connected in parallel and coupled in open circuit with a respective pair of wheel driving motors. A flow divider is provided in each circuit for dividing the pressure fluid delivered by the respective pump to the wheel driving motors of the associated pair.

Abstract: A hydraulic system for controlling the displacement of a plurality of variable displacement pumps driven by a single prime mover including a source of pilot fluid under pressure including a fixed displacement pump adapted to be driven by the prime mover proportional to the speed thereof, a double-piloted, underspeed valve having an inlet and an outlet, the outlet being adapted to be connected to the variable displacement pumps for controlling displacement thereof, a conduit connecting one of the pilots to the source, an additional conduit, including a flow restricting device, connecting the other of the pilots to the source, and a summing valve having ports adapted to be connected to respective ones of the pumps, a port connected to the second conduit and a port connected to the inlet of the underspeed valve.

Abstract: A hydrostatic transmission has a pair of variable displacement overcenter hydraulic pumps and first and second rotary servo valves. Each servo valve has a housing connected to the respective pump and a valve spool rotatably positioned within the housing for controlling the output displacement of the respective pump. A mounting plate extends between and is releasably connected to the housings of the first and second servo valves. A first device is connected to the valve spool of the first servo valve for selectively rotating said first servo valve spool, said first device being mounted on said mounting plate adjacent said first servo valve spool. A second device is connected to the valve spool of the second servo valve for selectively rotating the second servo valve spool, said second device being mounted on said mounting plate adjacent said second servo valve spool.

Abstract: The hoist drum of a mobile crane employs a controllable kinetics torque converter for transmitting power from a prime mover to the hoist drum. Apparatus and method are provided for controllably varying the density of the working fluid in the torque converter to regulate the capacity thereof and for keeping the variable density working fluid above a predetermined pressure level so as to prevent unwanted cavitation. The apparatus comprises means for supplying to the torque converter a working fluid comprising a mixture of liquid and gas, means for maintaining the fluid above a predetermined pressure level to inhibit cavitation in the working fluid, and means for selectively varying the density of the working fluid to selectively vary the capacity of the torque converter by varying the volumetric proportions between the liquid and the gas.

Abstract: A control system has override for fluid operated work elements served by at least two variable displacement pumps each serving a separate circuit. At least two work elements are served by the first circuit and at least one work element is served by the second circuit. The discharge rate of the first pump is controlled by a signal delivered from a summing valve in response to the pressures of the first and second circuits during operation of a preselected one of the work elements of the first circuit and controlled by a modified pilot pressure signal in response to operation of only the other work element of the first circuit.

Abstract: A control device for a hydrostatic drive, especially for a fork lift truck, in which an engine drives a reversible variable delivery pump which supplies fluid to a fluid motor connected to the drive wheels of the lift truck. A reversible actuator is connected to a control element for the pump and is connected through a reversing valve with a further engine driven pump. The rate of movement of the actuator is controlled in the opposite directions of movement thereof. The truck includes a lift cylinder supplied by a still further engine driven pump, and when the lift cylinder is under pressure, the rate of movement of the actuator is controlled at a still slower speed of movement in at least one direction of movement.

Abstract: The shiftably supported, rotatable feed rolls on a forage harvester or other material processing machine are operably coupled to a control lever on the hydraulic pump regulating the feed roll drive motor such that the angular velocity of the rolls is increased in response to shifting movement of the rolls away from one another, thereby enabling the rolls to readily rid themselves of a larger-than-normal slug of material should the same be encountered during harvesting. An additional control lever of a second hydraulic pump regulating another drive motor for the standing crop cutter and gathering elements of the harvester is operably coupled to the first control lever by a lost motion connection that permits the control levers to be shifted simultaneously for in unison manual operation of the motors, yet the first lever may be actuated independently by the feed rolls to control the first drive motor in response to relative shifting movement between the rolls.

Abstract: Apparatus for imparting reciprocating motion to a double-acting hydraulic piston and cylinder motor assembly. Hydraulic fluid is supplied through pressure lines alternately to opposite ends of the cylinder by two pumps. The pumps are operated so that one is on its pressure stroke while the other is on its suction stroke. The valving is such that fluid flowing out of the cylinder is discharged to an unpressured reservoir and fluid flowing into the pumps on their suction strokes is drawn from the same reservoir.

Abstract: A hydrostatic transmission is disclosed which includes a pump assembly in which a main pump, a charge pump, and an auxiliary pump are commonly housed and are drivingly connected to a single shaft assembly. An external fluid connection is provided through which fluid is directed from the auxiliary pump to a power take off, and valving is provided to short circuit the auxiliary pump when power is not demanded. Means of controlling the rate of operation of the valve are also provided to prevent excessive pressure rise rates at the outlet of the auxiliary pump upon actuation of the valving.

Abstract: A hydraulic system for mobile industrial equipment wherein the wheels or tracks of the mobile equipment are driven by a hydraulic transmission system having an engine-driven pump assembly, and wherein the hydraulic accessories mounted on the equipment are powered by a separate engine-driven hydraulic pump which draws its fluid from the hydraulic transmission pump assembly, and particularly the charge pump component thereof.

Abstract: An hydraulic feed control system for feeding or retracting a rotary rock drill relative to the work in a selected one of four modes; namely, standard feed; regeneration feed; standard retract; and rapid retract. The system includes an hydraulic circuit controlling the feeding and retraction of feed cylinders connected to the drill; a pair of hydraulic pressure supply sources; and a pair of manipulative control valves. A primary one of the valves controls flow from one of the sources directly into the circuit; and the other control valve is selectively operable to direct flow from the other source through the primary valve into the circuit so as to combine the flow from both sources for the regeneration feed and rapid retract modes.

Abstract: A device for rotating a turbine, particularly during starting, comprises a positive displacement-type main oil pump which has a main pump suction which is connected to the discharge of a high pressure oil pump which also has a connection to supply oil to the bearings. An auxiliary oil pump is mechanically coupled to the high pressure pump and it is also hydraulically connected in series to the high pressure pump. When the pressure builds up between the high pressure pump and the main pump, the main pump may be driven as a motor by the high pressure pump to effect a turning of the turbine.

Abstract: A hydrostatic transmission is provided with a variable capacity pump and a variable capacity motor. A control is operable to operate sequentially the pump and motor. A second control is provided to operate on the pump to override the signal to the pump from the first control without altering the setting of the motor. The first control thus acts as a ratio selector and the second control as a clutch.

Abstract: A load sensitive hydraulic circuit for material handling equipment is energized by a prime mover. The hydraulic circuit includes variable displacement pumps coupled to the prime mover and having pressure and flow compensating control means for varying the volumetric output. Each pump is connected to a valve bank which controls various hydraulic actuators of the material handling equipment. Load pressure feedback is provided to the pump compensators for establishing pump flows to operate the actuators at a fixed pressure differential in excess of load pressure. The valve banks contain pressure compensated valves for providing desired fluid flow rates and speeds in the hydraulic actuators. Means are provided to sense reductions in the prime mover speed resulting from excessive hydraulic loads.

Abstract: Disclosed herein is a drive and swing control system for an excavator wherein the swing pump may selectively direct fluid to the drive motors of the vehicle when the swing motor of the vehicle is not in use.

Abstract: An injection molding machine wherein the ram in the injection cylinder can be moved at several speeds and can be subjected to different fluid pressures by an apparatus having a two-way valve whose inlet is connectable to one or more pumps by way of discrete check valves and whose outlet is connected with a chamber of the injection cylinder by a conduit containing an electrically adjustable pressure relief valve. The valve member of the two-way valve is movable between a first position in which it completely seals the inlet from the outlet and several second positions in which it acts as a flow regulating means to permit the fluid to flow from the inlet to the outlet at a selected rate. The valve member is movable by a solenoid-operated pilot valve which cooperates with a stop extending into the path of movement of the valve member and being movable axially by a reversible motor which is controlled by the programming system of the injection molding machine.

Abstract: A hydraulic control system for use with a vehicle having an earthworking implement for selecting the speed range and for locking the vehicle in a forward drive condition.

Abstract: An apparatus with a motor driven material removing tool for cutting, drilling, milling, sawing or grinding of concrete, stone or the like. The apparatus comprises three spaced apart operational groups, namely a working group, a vacuum source and control group, and a driving group. The groups are mobile and interconnectable and disconnectable by hoses and electrical cables. The working group comprises an interchangeable tool, such as a drill, drive motor means for driving and advancing the tool, and a tool holding device mounted on the outside of a rigid suction bell. The vacuum and control group includes vacuum producing means and electrical and fluid control units. The driving group has at least one hydraulic pressure pump with motor means for generating the hydraulic power for driving and advancing the tool.

Abstract: A fluid power system comprising a steam generator connected to a hydraulic pumping device for delivering steam under pressure to the device for driving the same, while steam is returned to the steam generator via a condenser. The hydraulic pumping device is connected by means of suitable conduits to a plurality of hydraulic motors for driving the same and the conduits include valving means for controlling the direction of fluid between the hydraulic pumping device and the hydraulic motors and returning fluid to a reservoir from which fluid is initially drawn by the hydraulic pumping device. The hydraulic motors provide a rotary output for driving the wheels of a vehicle on which the fluid power system is used. The system further comprises valve means for controlling the pressure at which the system operates.

Abstract: A synchronized vehicle fluid drive system includes a vehicle, a pair of hydraulic motors operative to drive the opposite sides of the vehicle, a dual source of fluid pressure, a pair of open loop circuits individually communicating with the sources of fluid pressure and individually having a distributor valve for selectively communicating its respective fluid pressure source with one of said motors for operation thereof, and an equalizing line disposed in fluid communication intermediate the open loop circuits for assuring that the input flow to each of the motors is substantially the same when straight line travel of the vehicle is desired. Advantageously, a blocking valve may be disposed in the equalizing line for deactivating it upon receiving a steering signal.

Abstract: A mechanism with only two dynamic components, in which rotating crank motion is converted to intermittent rotation of an elongate rotor within a generally triangular chamber and vice versa. When the rotor and chamber are enclosed, the mechanism becomes a positive displacement fluid pump or motor capable of converting rotational torque into fluid pressure and vice versa; a high volume of fluid moving through a small device at comparatively low shaft speed. Further modification of the mechanism permits the rotor to slide axially while rotating, resulting in a variable displacement rotary fluid pump or motor. Adaptations of the invention provide: shaft drives having continuously variable speed ratios; fluid energy transformers wherein flow and pressure may be continuously converted into variably different flow and pressure; and continuously variable, gearless automotive transmissions. Additional capabilities include efficient pneumatic motors, compressors, and external combustion engines.

Abstract: An energy conserving hydraulic system for a lift truck or the like including a hydraulic tilt cylinder and a hydraulic lift cylinder subject to varying load requirements, manually operable valves for controlling the cylinders, a first, high volume hydraulic pump, a second, low volume hydraulic pump, a reversible, bidirectional DC motor for simultaneously driving both the pumps, and a piping system connecting the pumps to the valves such that for one direction of drive of the motor, the first pump will deliver a high volume of hydraulic fluid to the valve for operation of the lift cylinder, and for the other direction of drive of the motor, the first pump will be unloaded. A conduit is also arranged such that for the other direction of drive, the second pump will deliver a low volume of hydraulic fluid to the valve for directing the same to the tilt cylinder. An electrical direction control for controlling the direction of drive is responsive to the valves.