Abstract: An electromagnetic actuator utilizing a fluid pressure obtained from an electromagnetic pump, wherein according to the present invention, there is provided a responsive member displaceable in response to the pressure of a fluid forced into a second chamber from a first chamber. The responsive member displaceable as described can operate a valve member or the like coupled thereto in an on-off control or a proportional control with a large stroke in a reliable manner.

Abstract: This invention is directed to a wobble-torque hydraulic transmission device which has variable forward and reverse speeds and is also provided with a straight-through drive feature. The device is provided with a coaster brake feature that prevents the device from running away when going downhill. Also, the device is provided with a brake assembly that prevents rotation of the piston-pump means during forward and reverse operation but permits rotation for straight-through drive.

Abstract: A hydraulic supply system of a pulsatory press has two pumps (4 and 5) supplying through non-return valves (8 and 9) and through overflow valves (10 and 11), two slide dividers (17 and 19). The divider (17) in the position I directs oil to the working space V.sub.n under the servo-motor piston, whereas the divider (19) directs oil to the rotary divider (20) wherefrom a pulsating stream of oil gets into the working space under the part of the piston of a smaller diameter and into the run-off. The divider (17) in the position II directs oil to the space V.sub.p over the servo-motor piston at a simultaneous connection of the space V.sub.w via a slide valve (24) with the run-off, whereby the value of pressure in the space V.sub.p over the servo-motor piston is limited by means of an overflow valve (15).The conduit supplying oil from the divider (19) to a rotary divider (20) is connected via a cut-off valve (22) and a throttle valve (23) with a conduit supplying oil from the divider (17) to the space V.sub.

Abstract: Power steering pump is employed to provide power for engine cooling fan drive. Bypass oil or bypass oil in addition to return oil is routed from the power steering gear through the fan drive motor for improved fan drive operation.

Abstract: The disclosure relates to improvements in a hydraulically-actuated control device used in an operation unit of treatment chair and the like in an interlocking relation with reciprocating movement of a hydraulic piston. The device is of the construction in which two control valves slow in closing and opening operation are disposed in the oil supply and discharge passages leading to a hydraulic cylinder having a hydraulic piston therein so as to prevent shock in starting and stopping of the operation unit by controlling opening and closing of the two control valves and operation of the hydraulic pump disposed in the oil supply passage.

Abstract: A lockable valve in a hydraulic system comprising a valve body, a cylinder, a piston in the cylinder, and an inlet port and two outlet ports, one of the outlet ports leading to a bypass line and the other of the outlet ports leading to an operational hydraulic cylinder; the piston being slidable in the cylinder to selectively close either of the outlet ports. The valve includes a manually lockable means to lock the piston in the position in which the outlet port to the hydraulic cylinder is closed and being spring biased to close the outlet port leading to the bypass line and simultaneously to open the outlet port leading to the hydraulic cylinder when the lockable means is unlocked. An additional safeguard against the theft of vehicles employing hydraulic systems to power auxiliary equipment is provided by using this valve in the hydraulic line between the pressure side of the pump and the control valve of the auxiliary equipment.

Abstract: A gear machine comprises two helical gears (1, 2) in mutual mesh for compressing or pumping a fluid. The suction side of the machine can be made conventionally. The outlet port (4) of the machine is made as a plurality of holes (14), extending in towards the meshing zone at one side of the gear pair. The plurality of holes opens at one end (14a) within a Y-shaped area comprising the union of the surfaces which are each defined by the respective gear top and bottom circles (K, L) between a plane (P) through the axes of the gears and a gear radius (R) forming an angle to the axis plane at most attaining B .times. (1/R) .times. tangent .beta., where B is the width of the gear pair, R is the outside circle radius of the respective gear, and .beta. is the helix angle of the gears. At their other ends (14b), said holes are connected to a duct (6) at axially separated places in the duct, in the same order as they in the peripheral direction of the gears, open out onto said end surface.

Abstract: A hydraulic drive is retrofitted with an on-off switching facility. To this end, a block is provided having a front portion fitting the drive at adjacent inlet and outlet openings and having a rear portion opposite the front portion. The block is provided with a first through-opening leading from the rear portion to the front portion for communication with the inlet opening, and with a second through-opening leading from the rear portion to the front portion for communication with the outlet opening. The first through-opening at the rear portion of the block is adapted for reception of a fitting or a hydraulic fluid delivery hose which ordinarily would have been received in the above mentioned inlet opening. Similarly, the second through-opening is adapted at the rear portion of the block for reception of a further fitting for a hydraulic fluid return hose which would otherwise have been received in the above mentioned outlet opening.

Abstract: A system for mechanically or hydraulically driving or powering equipment in underground mines off an advance flight of a belt conveyor, in which an assembly of a spaced and drivably connected drive roller and pump and a common base is releasably mountable on wire ropes or other supporting members at opposite sides of the conveyor for selective positioning longitudinally of the conveyor beneath the conveyor belt's advance flight and is vertically adjustable relative to the advance flight for adjusting the driving engagement of the drive roller with that flight for either continuous or intermittent drive of the drive roller and pump while the belt is running.

Abstract: A hydraulic power pack having a prime mover driving a plurality of hydraulic pumps, a hydraulic circuit including a reservoir connected to an inlet of said pumps, an outlet circuit from said pumps, one or more pressure relief valves in the outlet circuit and a plurality of external connectors on the outlet circuit. The connectors and the relief valves are arranged so that different hydraulic flow and pressure characteristics may be obtained from each connector. Each connector has a flow and a return line, the latter being connected to the reservoir. Valves provided in the hydraulic circuit are responsive to zero flow in the return line of each connector and are adapted to divert the hydraulic flow directly to the reservoir without restriction.

Abstract: Flow from a pressure source is bidirectionally conducted to a prime-mover driven, bidirectional, positive displacement pump and in-series flow restrictions; the pressure source and flow restrictions functioning to provide the reference flow rate; the pressure gradient across said pump bidirectionally signaling the error in prime-mover speed. Means responsive to said pressure gradient provide proportional plus integral control of the prime-mover speed.

Abstract: An agricultural tractor is provided with a hitch and draft control system hydraulically related to a plurality of other hydraulic functions. The hydraulic fluid distribution is preferenced by a priority valve including a variable orifice in series with the hitch and draft control system. The variable orifice acts as a raise rate control device and also as a controlling member for a load sensing variable displacement pump.

Abstract: A controller for fluid pressure operated devices such as vehicle power steering systems. The controller is of the type having a primary, rotatable valve member and a follow-up valve member and including a fluid meter having a metering member coupled to the follow-up valve member. The valving defines a central reference plane perpendicular to the axis of rotation of the valving and the various ports and passages defined by the primary and follow-up valve members are generally oppositely and equally disposed about the central reference plane. This valving symmetry reduces internal leakage and steering wheel precession. The controller includes a load signal circuit, including a pair of load sensing grooves oppositely and equally disposed about the central plane.

Abstract: A transmission control system (10) for a transmission including a torque converter (66) has fluid inlet and fluid outlet passages (64,80) connected to the torque converter (66), a pressure regulating valve (20) for relieving fluid from a pressure source (12,16) to the inlet passage (64) of the torque converter (66), and a flow limiting passage (96) directly connecting the inlet and outlet passages (64,80) for continually bypassing fluid past the torque converter (66) and controlling the pressure drop thereacross.

Abstract: A fluid system (10, 10A, 10B) which supplies two work systems (26, 38) with respective different fluid flow rates, including a pressure-flow compensated pump (12), a first control valve (18) for delivering the fluid to one of the work systems, a second control valve (28) for receiving the fluid from the first control valve and delivering the fluid to the other of the work systems (38), a first device ([20,42,50] or [20,56,58] or [20,90,96]) coupled between the pump output and the first control valve, for providing one control signal causing the pump to produce one flow rate of fluid for activating the one work system (26), and a second device ([20,40,44,46,50] or [22,58,66,72,78] or [22,88,92,96,102]) for overriding the first device for providing another control signal causing the pump to produce another flow rate of fluid for actuating the other work system.

Abstract: A pressurized fluid supply for an auxiliary power steering system includes a regulator valve assembly controlling the output pressure of a fluid supply pump under the opposing influences of the pump discharge pressure and a signal feedback pressure from a fluid operated servomotor. An adjustable bias applied to the regulator valve assembly establishes a low idling discharge pressure for the pump while no steering action is being performed by the servomotor to which the pump is connected by a control valve biased to a flow blocking position.

Abstract: A hydrodynamic control coupling having a toroidal working chamber defined by a primary bladed wheel connected with a driving motor and a secondary bladed wheel connected to the driven element; a draining device for draining working fluid from the working chamber; a filling pump supplies working fluid to the working chamber; a valve varies the filling flow to the working chamber; the valve is a flow divider comprised of two interconnected valves including respective valve elements mounted in tandem on a common shaft which is shiftable axially; each of the interconnected valves includes a respective valve seat; as one valve element is moved away from its valve seat; the other valve element is simultaneously moved toward its valve seat; at least one of the valve elements and its seat is tapered to an acute cone angle, with other conically tapered shapes also being disclosed for one or both of the valve element and/or valve seat; one valve chamber supplies working fluid to the working chamber; the other valve cha

Abstract: A system including a hydraulic pump unloaded by a first system relief valve which is piloted by a remotely controlled two position directional valve. A second system relief valve in a hydraulic cylinder exhaust line is also of the pilot operated type. A manually operable valve in the truck cab pilots the second system relief valve to provide the operator precise manual control of cylinder discharge and speed of dump body lowering. A modified system includes a solenoid actuated two position directional valve for zero back pressure pump unloading. A hydraulic lift cylinder exhausts fluid during dump body lowering past pilot controlled relief valve the pilot line of which is branched permitting separate or combined control of the pilot flow by a manual or a solenoid actuated valve. A further modified system for both truck and trailer dump body control includes a pilot operated relief valve controlled by a solenoid valve for dumping pump output at low pressure.

Abstract: A hydraulic control system is provided including a fluid reservoir, a variable displacement pump having a fluid input in fluid communication with the reservoir and having a fluid output, and a fluid actuated displacement control mechanism for controlling the displacement of the pump. A control valve is placed in fluid communication with the fluid output of the variable displacement pump and with the reservoir and is adapted to control the flow of fluid to a fluid actuated device. The control valve includes means for developing a control pressure signal.

Abstract: An arrangement for controlling the operation of a fluid-displacement machine, such as a hydraulic pump or motor, which is equipped with an adjuster that adjusts the machine toward higher and lower throughputs in dependence upon the pressure of a control fluid acting thereon, includes a control valve which communicates the adjuster either with a high-pressure zone or with a low-pressure zone of a control circuit in different ones of its terminal positions. In addition thereto, the arrangement includes a pressure-limiting valve interposed between the low-pressure and the high-pressure zones of the control circuit. Both the control and pressure limiting valves are acted upon by the control fluid, the pressure of which is controlled by a common regulating valve.

Abstract: A control system for stopping a hydraulic motor in a predetermined position comprises a valve connected in parallel across the motor, the valve having a closed position and an open position in which flow is via a throttle orifice. When the motor is being driven normally the valve is closed. When the main control regulator for the motor is moved to stop the motor, the valve is automatically opened to allow limited fluid flow through the motor during a slowing down phase. A detector senses when the motor is a predetermined distance from its desired stopping position, and moves the valve to its closed position. Overload valves are provided to prevent overpressures.

Abstract: The control system has an adjustable flow-rate pump and a fixed flow-rate pump which is supplied with hydraulic fluid via a supply conduit. A first throttle is interposed in this conduit and produces first signals in form of pressure differentials in dependence upon variations in the rotational speed of an ungoverned combustion engine which powers the hydraulic drive, which signals trigger flow-rate adjustments of the main pump. A second throttle is also interposed in the supply conduit and produces second signals in form of pressure differentials in dependence upon variations in the load upon the hydraulic motor of the hydraulic drive, which signals trigger movements of the throttle flap of the internal combustion engine towards the open or closed position thereof.

Abstract: Disclosed is a fluid coupling which includes: a housing being used as a rotary driving member; a rotor rotatably mounted in the housing and being used as a driven member, a fluid pump having a pump chamber defined between the housing and the rotor; a fluid inlet port and a fluid outlet port; and a fluid circulation passage between the chamber and the housing, such that fluid in the pump circulates from the fluid circulation passage into the pump chamber through the inlet port and from the pump chamber through the outlet port into the fluid passage.

Abstract: A hydrostatic transmission having a variable displacement pump whose control element varies the transmission ratio and output direction of the transmission is controlled by a hydraulic servomechanism including a direction-reversing valve and a cylinder connected to this valve. A direction selector acts upon the valve and a mechanical or hydraulic locking mechanism is provided to prevent shifting of the valve until the control element of the pump has been restored to its neutral position before direction change.

Abstract: A hydraulic engine having a fluid pump for pumping a fluid medium under pressure to a fluid motor connected to the pump for being actuated by the fluid medium under pressure received from the pump. A control system regulates operation of the pump and motor so as to permit appropriate variation of speed of an output shaft of the motor. The fluid motor is a reciprocating motor, the piston of which is connected directly to a mechanism for translating the reciprocating motion into rotary motion, while the reciprocating movement of the pistons simultaneously actuates valves for sequentially directing the fluid medium under pressure to opposite ends of the piston in order to obtain a double-acting piston and cylinder operation.

Abstract: In an hydraulic system in which an hydraulic accumulator is charged with hydraulic fluid under pressure by means of an hydraulic pump which draws hydraulic fluid from a tank, and an unloader valve disposed in a supply line between the pump and the accumulator is operative to prevent the accumulator from being overcharged and to allow the pump to re-charge the accumulator should the pressure stored therein fall below a desired minimum value, the unloader valve incorporates a control valve, and a pressure responsive slave which is operated by fluid pressure under the control of the control valve.

Abstract: An automatic control system for a hydrostatic transmission having a control circuit receiving a control flow from a control pump which represents a speed of a prime mover and valve components including a single adjustable valve which creates a delta pressure signal to control the transmission ratio which controls the speed of the prime mover.

Abstract: A system for controlling the acceleration and/or deceleration of a mechanical power drive having a rotatable power output element and a rotatable reaction element with a hydraulic or pneumatic brake mechanism connected thereto, in which a motor drive pump or other pressure creating device is connected by a fluid pressure line to the brake mechanism, and a bleed line with an electrically controlled valve therein is connected to the fluid pressure line for relieving the pressure delivered by the pump to the brake mechanism. An electrical system responsive to the rotational speed of the output element of the power drive controls the pressure creating means to control the acceleration and/or deceleration rate of the output element. An accumulator and a pressure responsive relief valve are preferably included in the system to assist in regulating the pressure delivered to the brake mechanism, and a dump valve and overload control device are normally included in the system.

Abstract: A fluid controller is disclosed of the type including a primary valve member, and a follow-up valve member. The controller includes a load signal port and a load signal chamber. Fluid is communicated from the inlet port to the load signal chamber, and the valve members define a neutral orifice communicating between the load signal chamber and the return port when the valving is in neutral. The valving defines operating orifices communicating fluid from the load signal chamber to the main fluid path, downstream of the main flow control orifice, when the valving is shifted away from neutral. The operating orifices have a smaller orifice area when the valving approaches maximum deflection. The result is a substantially higher differential operating pressure, and a higher flow rate than would otherwise be possible at that particular valve deflection.

Abstract: A fluid drive transmission in which a moving fluid is used to connect the drive and driven members together. The drive and driven members both comprise rollers having longitudinally mounted, spiral shaped vanes extending about their periphery. The rollers are mounted in end to end spaced relationship in a common housing with a greater radial spacing provided between the periphery of the driving member and the housing than between the periphery of the driven member and housing. The system further includes a combined apparatus for supplemental braking which includes a valve connected in a closed hydraulic path between the ends of the housing. The valve is effective to retard the pressurized flow of the fluid upon application of the brakes thus assisting in slowing down the speed of operation of the transmission and retarding the drive output.

Abstract: The control system for a hydraulic transmission comprises a throttle element which consists of a constant throttle and a spring charged adjustable throttle arranged in parallel or, alternatively, comprises a combination of a constant throttle with adjustable throttles. The adjustable throttle has a cross section varying in response to the operating pressure of the hydrostatic transmission. The moment of rotation of a hydrometer included in the transmission is determined by the fluid stream caused by an adjustable pump which is adjusted by a servomechanism controlled by the throttle element and thus forms a transmission control member.

Abstract: A valve assembly is provided in which a first poppet member and at least one subsequent poppet member each having a valve face engageable with a valve seat between first and second passages. A first and a subsequent pilot valve is operative for selectively establishing communication between a fluid reservoir and a space at one side of a piston portion of each poppet member and a pair of restricted flow passages are provided in each poppet member between such space and the first and second passages, such restricted flow passages being preferably formed in the poppet members with ball check valves provided therein. Such restricted flow passages operate upon closure of the pilot valve to develop a static pressure in the space corresponding to the pressure in the one of the first and second passage which has the higher pressure therein so as to move the poppet member to and hold it in its closed position in response to pressures applied from either of the first and second passages.

Abstract: A rotary hydraulic coupling of the type wherein the powered movement of a plurality of reciprocable pistons, which are carried and driven by a drive shaft, work in cylinders which are carried by a driven shaft, and wherein the varying backup pressure of incompressible fluid within the cylinders is relied upon to apply torque to and thus rotate the driven shaft. A sealed casing rotates in unison with the driven shaft and establishes an internal fluid reservoir, while the drive shaft projects into the casing and, by means of a crank arm, reciprocates the pistons. Inflow check valves leading from the reservoir allow fluid to be drawn into the cylinders while outflow check valves leading from the cylinders allow fluid to be forced directly into a manifold which is separated from the reservoir. The pressure attained in the manifold is reflected as backup pressure in the cylinders, such pressure varying the torque which is applied to the casing and driven shaft.

Abstract: A power brake valve and a related braking system are disclosed. The valve comprises a housing defining a first bore of large diameter and a second bore of smaller diameter, and annular pistons are slidably disposed within each bore. A biended rod, also slidable within the bores, carries reaction pistons which are radially extended to cover the annular flow space of the adjacent, associated annular pistons. When the rod is pulled in a power mode of operation, each annular piston moves toward the associated annular piston to restrict and halt the normal flow of fluid through the annular piston and create a movable end wall. As pressure rises within the chambers, pressurized fluid is discharged from the valve to brake units to cause braking action. In a manual mode of operation, pulling action on the rod causes a relatively large quantity of relatively low pressure fluid to be discharged from the first chamber so as to quickly and effectively take up systemic clearances within the brake system.

Abstract: A hydraulic follow-up for use with a hydraulic system placed between a rotating input member and a rotating output member. The hydraulic system is a hydrostatic transmission for driving a tractor, and comprises a hydrostatic pump and a hydrostatic motor driven by the pump. When the hydrostatic pump is angularly shifted with respect to the input member, the shifting is controlled by the hydraulic follow-up, which also shifts the motor in relation to the output 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: A control arrangement for a hydrostatic drive comprises a gear pump driven by an internal combustion engine and supplying fluid to a fluid motor. The control arrangement is constructed in such a manner that even at a high number of revolutions per time unit of the internal combustion engine, the fluid motor may be operated at a low number of revolutions.

Abstract: A hydraulic control device for use in a hydraulic system having a pump supplying fluid from a reservoir to a working circuit. The control device detects leaks in the working circuit by monitoring the level of hydraulic fluid in the reservoir. In the event of a drop in the level of hydraulic fluid beyond a predetermined low level, the control device automatically diverts the fluid output side of the pump to the fluid input side to prevent further loss of fluid in the working circuit and to safeguard against cavitation in the pump due to the low level of fluid in the reservoir. The control device also senses excessive pressure peaks in the working circuit and operates to relieve the excessive pressure peaks by automatically venting a portion of the fluid on the output side of the pump to the reservoir.

Abstract: A power steering device has a distribution valve inserted between a high pressure source formed by a pump and a reservoir for creating a pressure difference in a fluid motor connected to the steering linkage, in response to application of a torque to the steering shaft of the vehicle, thereby providing assistance to operation of the steering linkage. A by-pass passage connects the high pressure output from the pump with the reservoir and the cross section of the by-pass passage is controlled as a function of the pressure difference between the chambers of the fluid motor. The means for controlling the cross section of the by-pass passage comprise a slidable piston disposed substantially transverse in the path of the fluid flow. The piston comprises grooves and lands for respectively allowing and interrupting fluid flow in the by-pass passage. The axial position of the piston is a function of the pressure difference.

Abstract: The invention relates to a control valve of a hydraulic booster having an inlet orifice adapted to be connected to a hydraulic pump, an outlet orifice adapted to be connected to an open-center valve, a working orifice connected to the booster pressure chamber and an exhaust orifice connected to the reservoir. The control valve comprises mainly a first and a second valve members respectively controlling fluid connection between the working and the exhaust orifices. The first valve member is secured to a cylinder which partly covers the outlet orifice when this valve member is unseated.

Abstract: A hydraulic clutch-controlled transmission gear detent system including a gear shiftably mounted on a shift rail and a detent member interposed between the rail and the gear for holding the gear in a shifted position. A hydraulic system, including a valve and a valve controller, such as a clutch pedal, are associated with the detent member to hold the detent member in securing position relative to the shifted gear.

Abstract: A control arrangement for a hydraulic power transmission comprises a main valve slide, a precontrol valve slide for controlling the main valve slide, as well as an auxiliary valve slide for controlling flow of pressure fluid through a pressure channel leading from a pump to a hydraulic consumer, for instance to fluid operated cylinder and piston means. The arrangement includes further a control conduit branching off from the pressure channel and leading over a throttle, the precontrol valve slide and the auxiliary valve slide, in which the latter is movable between two end positions under the influence of a spring and the hydraulic pressure in a pressure chamber and arranged to control passage of fluid through the control conduit, and two adjustable throttles in the control conduit, respectively formed by the auxiliary valve slide and the precontrol valve slide.

Abstract: A hydraulic system is disclosed which combines hydrostatic and implement motors and includes a plurality of hydraulic motors with a variable displacement pump supplying fluid for the motors and a plurality of directional control valves for selectively directing fluid from the pump to the respective motors and includes pressure varying means connected to each of the directional control valves for varying a pilot pressure communicated to vary the displacement of the variable displacement pump in direct relationship to the shifting of the directional control valves.

Abstract: The rotary machine comprises: a stationary housing having an interior profile defining a monolobic configuration; a rotary cylindrical body arranged eccentrically in the housing and including a series of arc-shaped segments mounted in circular alignment in the housing and spaced to define therebetween a series of radial slots; interfitted double vanes slidably received in the slots; and counterweight means mounted in the body and disposed adjacent each blade portion of the double vanes; during rotation of the body, the counterweight means at one end of one double vane gradually opposes the movement of the said one double vane while, simultaneously, at the opposite end of the same double vane, the counterweight means are gradually removed from this opposite end of the blade portion whereby the centrifugal forces acting on the double vanes are balanced and vane pressure on the housing is minimized.

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 fluid circuit comprises an engine-driven pump for communicating pressurized fluid through a combined unloading and relief valve and to an implement control circuit of a construction vehicle. Actuating means are provided for selectively opening the valve during engine start-up to reduce fluid pressure in the valve and implement control circuit to a first predetermined level. An override means is operatively connected to the actuating means for preventing the valve from opening when the fluid pressure exceeds a second predetermined and operating level which is higher than the first predetermined level.

Abstract: A power device utilizing a housing and rotor assembly receiving pressurized, non-compressible liquid from a pump for driving an output shaft which may be employed for many purposes. The housing is communicated with and positioned on top of the tank or sump for the liquid and the pump includes an intake associated with the tank for circulating the liquid which may be in the form of an oil, such as that used as transmission fluid, or the like. A bypass control is provided for the pump for varying the output characteristics of the shaft and a DC electric motor drives the pump. The electric motor is associated with an electric power system for providing electrical energy to the pump motor which includes an alternator or equivalent charging device, battery assembly and an inverter and convertor, in one embodiment, associated in a manner to supply sufficient electrical energy to the pump motor for driving the pump.

Abstract: An overspeed protection control for an engine which drives at least one pump and having valve means selectively operable to cause an increase in pressure in a circuit supplied by said pump and a resulting increase in load torque on the engine. Means responsive to the engine speed exceeding a predetermined value causes operation of the valve means, and includes a control valve positionable either in response to a pressure differential across an orifice in the circuit supplied by the pump with the pressure differential being an indication of flow rate and, therefore, engine speed, or operable by a control circuit including means for detecting engine speed.

Abstract: A device for limiting in a contact-free manner the movement of hydraulically operable mechanical elements, especially for bucket wheel loaders. The device includes a front carriage and a rear carriage. One approaching initiator each is provided on that portion of the front carriage which faces the rear carriage, and the arrangement is such that when turning the steering wheel and when the front carriage angularly approaches the rear carriage, a pertaining thyristor is triggered so that a magnetic valve is energized which through hydraulic control conduits communicates with the tank.

Abstract: A fan drive system comprises a constant pressure ring main circuit from a motor driven pump to, for example, three variable capacity motors driving three fans. The motors are connected in parallel with each other and in series circuit with the pump and each has a piston and cylinder device supplied with pressure from the ring main. A variable restrictor controlled by a temperature probe sets the pressure acting on each piston and cylinder device so that each fan is speed controlled in accordance with temperature.