Abstract: A device for the power-assisted control of a hydraulic transmitter is disclosed which includes a transmitter cylinder having a first and second bore provided therein, a main piston with a bore hole, disposed in the cylinder, valve means disposed in the bore of the cylinder, a fluid source communicated with the cylinder, a control piston movably disposed in the second bore and having a control section and a second section formed thereon wherein the control section of the control piston is larger than the second section of the control piston.

Abstract: A device of the type wherein a gas pressure is converted into an oil pressure and the resulting oil pressure is exerted to drive an actuator. A pair of gas-oil reservoirs are coupled with each other via a conduit wherein an automatic oil level control valve is disposed to close the conduit when the actuator is in operation and the gas pressure in the reservoirs are not balanced and open the conduit when the actuator is not in operation.

Abstract: A control valve adapted for use in working machines for hydraulically controlling the lifting movements of the working machine such as a rotary blade or plow connected to a power machine, said control valve comprising essentially a change-over valve for connecting or shutting off a cylinder port to or from a pump port or tank port by a spool operation, and a compensator for guiding cylinder port pressure into an oil chamber of a plunger on the spring loaded side for bypassing the pump discharge oil opposedly to the pump pressure, and characterized by provision of a passage for connecting the oil chamber of the compensator on said spring loaded side into the tank port or cylinder port through said change-over valve, whereby when said change-over valve is at its neutral or dropping position, said oil chamber is communicated with the tank port, and when said valve is at its elevating position, said oil chamber is communicated with the cylinder port.

Abstract: An apparatus comprises a pair of tanks, a pair of pistons, coupling means interconnecting the pair of pistons in balance, a closed chamber and a reservoir provided within each of the tanks and partitioned from each other by the piston, a nozzle disposed at one end of the closed chamber, a valve provided on each of the pistons, rotatable means and liquid feed channels. The nozzle, the rotatable means and the liquid feed channels are positioned substantially at the same level as or above the upper end of the reservoir in the tank to circulate the liquid. The apparatus generates rotational power with greatly reduced energy losses.

Abstract: There is described a servo-control system incorporating a double-acting ram which is responsible for compensating electro-hydraulically for the imbalance in a servo-controlled load in order to achieve a high performance. To this end, a compensating loop is produced which slaves a balancing pressure P.sub.e to the variations in the imbalance. This pressure is exerted in one of the chambers of the ram, separately from the control pressure. It is governed by a pneumatic accumulator whose load is a function of the lack of balance between the pressure exerted by the imbalance and the balancing pressure.

Abstract: An apparatus for delivering power to a marine propulsion device comprises an engine, a propeller, and a transmission which operatively connects the engine with the propeller and which is operative between a neutral position and a drive position. The apparatus further includes a source of pressurized fluid, a cylinder and a differential piston movable within the cylinder in response to pressurized fluid. A first conduit continuously conducts pressurized fluid from the source to the cylinder to locate the piston in a first position in the cylinder, and a second conduit conducts pressurized fluid from the source to the cylinder to locate the piston in a second position in the cylinder which second position is spaced from the first position. A flow control device communicates with the second conduit for selectively permitting the flow of pressurized fluid through the second conduit to displace the piston from the first position to the second position.

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: 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: Hydraulic system for operation of winches which are associated with powered friction pulleys for hauling a wire, the winch winding the wire onto the drum being provided with valves permitting the friction pulleys to idle freely when it is convenient to use the winch drum proper also for hauling the wire.

Abstract: In an hydraulic power system for operating a vehicle levelling system and braking system, an accumulator supplies both the levelling system and the braking system. The accumulator is connected indirectly to the braking system through a pressure limiting device, which disconnects the braking system from the accumulator when a predetermined pressure is reached.

Abstract: A hydraulic power pack having a framework, a prime mover driving a hydraulic pump, a hydraulic circuit including a reservoir and flow and return connectors. The power pack also includes an oil cooling system comprising a thermostatically operated valve and an oil cooler in the hydraulic circuit. The valve diverts flow of fluid to the oil cooler when the temperature of the fluid rises above a predetermined limit, before returning the fluid to the reservoir. The oil cooler has a pair of heat exchangers mounted at the respective outlets of a double acting centrifugal fan directly coupled to and driven by the prime mover.

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: A hydraulic rotary distributor comprising two rotary members respectively connected to an input shaft and to an output shaft, said members controlling through their relative angular position the supply of pressurized fluid to a hydraulic power-assistance motor. According to the invention, there are provided, in addition to the usual working chambers, additional reaction chambers which are fed with the same fluid pressure as the corresponding working chambers, the pressure in said reaction chambers being however limited to a predetermined maximal value thanks to devices automatically controlling the communications between said working and reaction chambers. For use particularly in power steering mechanisms for automotive vehicles.

Abstract: This wave-operated power plant comprises a perforated caisson breakwater in which propellers, or turbines, are mounted in the perforations or openings and drives hydraulic pumps connected thereto, which in turn drives a hydraulic motor coupled to an electric generator. One-way flap valves are mounted in the openings. Some of said flap valves allow the rushing waves to enter the caisson, while the other flap valves allow the water to flow out of the caisson.

Abstract: A drive system has an engine that operates a control pump and a hydraulic variable-displacement drive pump having a control element and connected to a hydraulic motor. A servocylinder operates the control element of the drive pump and is pressurized through a control line connected to the control-pump output. A control valve is connected between the control line and the sump of the system and is connected to the hydraulic line between the motor and the drive pump to reduce pressure in the control line when the higher pressure of the line between the drive pump and the motor rises within a predetermined range. Thus it is possible with a substantially constant engine speed to produce a substantially constant output torque, with only the displacement of the pump and pressure in the lines between the pump and the motor varying by appropriate control of the control-line pressure.

Abstract: A method and apparatus for linear and nonlinear control of a hydraulic press is provided with a feedback loop allowing the operation of a variable displacement pump to be selectively controlled with respect to either hydraulic pressure moving a piston in a cylinder, or the velocity of the piston. During controlled movement of the piston, a directional valve blocks a pump compensator so that the pump operates as a fixed displacement pump to provide fast response to feedback signals. Simultaneously, the directional valve connects a proportional pressure controller to a relief valve. During a period when the piston is maintained in fixed position, the directional valve is switched so that the proportional pressure controller now controls the pump compensator and the relief valve is blocked, so that energy consumption is substantially reduced.

Abstract: A hydrostatic transmission control system including a variable displacement pump driving a constant displacement motor arranged in a hydraulic circuit having a controlled by-pass valve interconnected for positioning the pump swash plate in two established positions corresponding respectively to a stand still position or a full speed position of the motor. A thermosensitive element is coupled to the valve control spool for bypassing the flow of the pump in the event of motor jamming.

Abstract: This specification discloses an off-road type vehicle employing an improved hydrostatic drive system having a variable displacement pump having an actuating member for varying displacement in at least one direction, wheel motors representing actuatable devices operable by fluid from the pump, hydraulic reservoir, serially interconnecting supply and return lines and an improvement comprising an over control compensation that includes high pressure relief valves on the high pressure supply lines; a neutralizing means for moving the actuating member back toward its neutral position responsive to hydraulic pressure released by the relief valves, and a bleed-off means connected with the neutralizing means and adapted to bleed-off high pressure hydraulic fluid to allow restoring operation and a bleed-off return for returning the bleed-off hydraulic fluid to the reservoir.

Abstract: A hydraulic control circuit especially for use with multi-function hydraulic devices, such as for industrial lift truck attachments, in which a combination of valve means are adapted to operate two or more hydraulic systems, the valve system being designed such that a minimum number of hydraulic conduits are required to connect the main hydraulic system to the hydraulic devices, as from a lift truck to an attachment supporting carriage on a lift truck upright, and no electric lines are required to be connected to switching devices between the hydraulic devices, such as to solenoid operated valves.

Abstract: A motor vehicle engine is arranged to drive the vehicle wheels through a mechanical transmission, an hydraulic system including a variable-output, reversible, hydraulic pump, a variable-output hydraulic motor usable reversibly as a pump and a two-speed gear box. The outlet and inlet of the pump are reversibly connected by delivery and return conduits respectively, through a distributor, to the inlet and outlet of the motor and an hydraulic accumulator is connected through a closable valve to the delivery conduit, the operation of the system being controlled by a microcomputer so that when the vehicle decelerates at a rate greater than that due to natural resistance, kinetic energy which is normally lost in the engine is stored in the accumulator and can subsequently be reused to drive the vehicle wheels, the engine being cut out or maintained at minimum power.