Abstract: An oil hydraulic cylinder configured to allow an object to be smoothly and continuously lifted without being clatteringly swayed and unnecessarily rotated by the oil hydraulic while supply of the oil hydraulic remains uninterrupted when an adjusting lever is manipulated for lifting and lowering operations, the cylinder comprising: a cap part protrusively formed thereon with a compression unit for forcibly generating oil pressure, an operation unit fixedly connected to an object for lifting, stopping and lowering the object and an adjusting unit for controlling the lifting, stopping and lowering of the object; a body part connected inside a body case to the compression unit, the operation unit and the adjusting unit and formed with a plurality of cylinders and pistons for carrying out an oil pressing operation; a base part coupled underneath the body part and formed therein with a predetermined flow route; an oil control part for controlling oil flowing in an oil route formed inside the base part; and a manipu

Abstract: A hydraulic tool including a frame having a hydraulic conduit system; a ram movably connected to the frame; and a multi-speed ram advancement system for advancing the ram in at least two different rates of movement on the frame. The multi-speed ram advancement system includes a hydraulic pump connected to the hydraulic conduit system of the frame; and a conduit tube extending into a hydraulic chamber inside the ram and fixedly connected to the frame. The conduit tube is adapted to conduit hydraulic fluid from the hydraulic conduit system into the hydraulic chamber inside the ram. The conduit tube is axially rotatably connected to the frame and longitudinally stationarily fixed to the frame.

Abstract: An electro-hydrostatic actuator having a sealed housing filled with a dielectric fluid. A motor driven pump and electronics for controlling the pump are all immersed in the fluid. The pump is arranged to deliver fluid from the housing to a hydraulic cylinder to control the positioning of the piston rod. A solenoid operated valve is integrated as a bypass or tip valve for quick fail safe position. The actuator is ideally suited to control various types of plunger valves. In one embodiment of the invention, the hydraulic cylinder is located outside of the housing and in another embodiment the cylinder is located inside of the housing.

Abstract: A battery powered hydraulic tool including a frame; a battery connected to the frame; a motor connected to the frame and adapted to be powered by the battery; and a hydraulic pump connected to the motor by a gear reduction transmission. The motor and gear reduction transmission are adapted to output a torque of the least about 160 oz-in with the gear reduction transmission being adapted to provide a gear reduction of between about 8:1 to about 15:1 or less, and the hydraulic pump being adapted to output at least about 6000 psi of pressure or more.

Abstract: An engine with an integral actuator for a vehicle having an implement needing control. The engine includes a crank shaft, and a pump in a housing and an actuator that extends from the housing. The pump is operably connected to the crank shaft to produce a flow of fluid, such as oil, from the pump to the actuator. A valve is operably connected to the pump or the actuator to selectively move the actuator.

Abstract: A multilevel speed regulation jack includes an input oil cylinder, an output oil cylinder, and a fluid conduit member between the cylinders. The output oil cylinder includes a cylinder body containing an annular space and a tube piston, which fits in the annular space. A sliding sleeve of the tube piston is movably positioned in the annular space. An annular in-flow oil chamber is formed between the end annular surface of the tube piston and the cylinder body, and a central in-flow oil chamber is formed between the inner central surface of the piston and the cylinder body. The fluid conduit member includes at least two parallel fluid channels connected to the central in-flow oil chamber and the annular in-flow oil chamber, respectively. A control valve in one of the fluid channels opens/closes the channel. The jack can automatically switch between different jacking speeds based on the load sensed by the system and therefore has a high jacking efficiency.

Abstract: The invention concerns a control system of a device for lifting a load placed on a carrying element displaceable between a low position and an elevated position.

Abstract: The invention relates to a control device for a working device (12) connected to a hydraulic circuit (10), especially for a load fork (16) which can be raised and lowered with a working cylinder (14) in a fork-lift truck, comprising a valve control unit which moves into an adjustment position when the load fork (16) is lowered even when carrying a load (18), a predefinable maximum volume flow being maintained in the hydraulic circuit (10). By providing the valve control unit with a pressure regulator (26) limiting a pilot control pressure for the control valve (28), once a predefinable regulating pressure differential is reached in the hydraulic circuit, said control valve moves into a regulating position in order to maintain the maximum volume flow and the known flow control valve is replaced in the main flow by a pressure regulator (26) disposed in the pilot control circuit (40) and which only needs to be dimensioned for low volume flows.

Abstract: A speed regulation jack comprises at least one input cylinder and one output cylinder, and parallel hydraulic lines between the input and output cylinders. A differential oil circuit is connected between the inlet cavity and the return cavity of the output cylinder, and a control valve is connected in series between the return cavity of the output cylinder and the oil tank, and this control valve controls the return oil of the return cavity. This speed regulation jack takes the magnitude of the load as its signal and transfers automatically between different lifting speeds, thus enhancing the lifting efficiency of the jack.

Abstract: An actuating device for a hydraulic lifting device has a body, a piston and a lever. The body has an inlet channel communicating with an oil tank and an outlet channel connected to a cylinder. The piston is moveably received in the body to divide a chamber into an upper chamber and a lower chamber that communicates with the inlet channel and the outlet channel in the body. Two check valves are respectively received in the inlet channel and the outlet channel in the body. A slight gap is defined between the periphery of the piston and the inner surface of the chamber in the body. Accordingly, some oil in the lower chamber is allowed to flow into the upper chamber when the pressure in the outlet channel is over a desired level, and the structure of the actuating device is simple.

Abstract: A manually operated zero-load rapid lifting hydraulic jack. The jack has a lifting arm and a lever which are connected properly together by contacting one another. A lifting arm is formed with an integral receiver portion, which could be in the form of a receiving hole, a receiving tube, a receiving block or any infinite variety of receiver configurations, such that one end of the lever can be inserted into or locate over those receivers as described above. In zero load, as the lever is being pressed downwards and the lifting arm axle serves as a fulcrum to drive the lifting arm to move upwards rapidly to a position of contacting with a lift point.

Abstract: A control device for hydraulically operated hoisting mechanisms used to raise and lower loads includes an electrically controllable throttle valve connected to a return line of the hoisting mechanism, and a pressure scale with at least one blocking position and one control position. The pressure scale operates in conjunction with an unblocking mechanism. When in its normal position, the pressure scale blocks the return line. The pressure scale assumes its control position in lowering of a load as a result of triggering of the unblocking mechanism. In the event of failure of the throttle valve, the pressure scale may be moved to its blocking position by the unblocking mechanism. In the event of failure of the pressure scale, the throttle valve assumes its blocking position. The load retention function is performed by two series-connected closed hydraulic actuators which can be electrically controlled individually.

Abstract: A hydraulic compression tool having a frame, a hydraulic fluid reservoir on the frame, a ram movably connected to the frame, a conduit system in the frame between the reservoir and the ram, a pump provided in the conduit system, a mechanical actuator provided in the conduit system for contacting the ram, and a bypass valve in the conduit system between a rear end of the ram and a channel of the conduit system to the rear end of the mechanical actuator. The conduit system is adapted to conduit fluid from, the pump against both the rear end of the ram and a rear end of the mechanical actuator. The bypass valve is located, at least partially, in a housing member of the mechanical actuator.

Abstract: A suspension system for motor vehicles includes level regulation for adjusting a predetermined height of the vehicle body. At least one piston-cylinder unit of the suspension system includes a work cylinder, a piston rod and a damping piston having damping valves. A pump is arranged between an oil reservoir and the piston-cylinder unit via corresponding inlet and outlet lines. The pump comprises a pump piston and a drive unit arranged so that a pressure of the piston-cylinder unit acts on a delivery side and on a driving side of the pump piston.

Abstract: A hydraulic rescue system comprises a fluid reservoir, a pump assembly having a plurality of pump modules, and a manifold assembly having a corresponding number of manifold modules. Each pump module includes an input port for drawing hydraulic fluid from the fluid reservoir and an output port for supplying hydraulic fluid under pressure to a hydraulic rescue tool. Each manifold module includes a fluid circuit that is adapted to fluidly connect the output port of one of the pump modules with a hydraulic rescue tool. A PTO adapter is connected to the pump assembly and is operably connectable to a PTO shaft of a vehicle transmission for operating the pump modules. In this manner, a number of different hydraulic rescue tools can be operated simultaneously with full pressure from the pump assembly.

Abstract: The present invention relates a jack assembly that may be lifted rapidly. A secondary shaft is mounted in a lifting column, and has a distal end screwed into an axial hole in the base. The main oil path is provided with a lower ball and an upper ball, and has a first oil hole connected to the oil hole of the secondary shaft, and a second oil hole connected to the inner oil chamber. The hydraulic oil pushes away the lower ball to flow through the first oil hole into the secondary shaft, so that the lifting column that has not worked may be lifted rapidly. The lifting column may work to increase the pressure of the hydraulic oil which flows through the second oil hole into the inner oil chamber, so that the lifting column may have a sufficient lifting force to lift an object.

Abstract: A pressing tool having an electric motor fed by a battery. The electric motor drives a gear pump with two rotor shafts which are accommodated in a hydraulic block. The rotor shafts are mounted in a gear housing on one side of the hydraulic block and in a cylinder housing of a piston cylinder unit which bears on an other side of the hydraulic block. This gear pump uses an extremely simple construction manner and simultaneously achieves a high delivery volume. The high delivery volume leads to an extremely low loading of the battery, by which its operational duration is increased.

Abstract: A hydraulically actuated tool comprising a frame; a hydraulic fluid pump connected to the frame; a ram movably connected to the frame and adapted to be moved relative to the frame by hydraulic fluid pumped by the pump; and a hydraulic fluid reservoir connected to the pump. The reservoir is located proximate an exterior portion of the frame along a path of at least about 180°0 relative to a longitudinal axis of the tool. The reservoir does not extend beyond a rear end of the frame.

Abstract: A hydraulic elevator system of an inverter control method directly controlling a flow amount of a pressed oil discharged from a hydraulic pump by a speed control of a motor driving the hydraulic pump, which can improve energy efficiency and stability. The hydraulic elevator system includes a reverse check valve connected between a hydraulic cylinder operated by the pressed oil to lift/lower an elevator car and a hydraulic pump driven to discharge the pressed oil, opened to pass the pressed oil by the pressure of the discharged pressed oil in a driving of the hydraulic pump, and closed to prevent the pressed oil from being reversed by using a pilot pressed oil of the hydraulic cylinder as a power source in a stopping of the hydraulic pump; and a pilot hydraulic cylinder operated by the pilot pressed oil from the hydraulic cylinder in order to apply an additional close force to the reverse check valve in the lifting/lowering or emergency stopping of the elevator car.

Abstract: A suspension system for motor vehicles includes level regulation for adjusting a predetermined height of the vehicle body. At least one piston-cylinder unit of the suspension system includes a work cylinder, a piston rod and a damping piston having damping valves. A pump is arranged between an oil reservoir and the piston-cylinder unit via corresponding inlet and outlet lines.

Abstract: A hydraulic cylinder in which the cylinder head contains a motor-driven fluid pump, fluid reservoir, and a main control valve for the cylinder. The cylinder includes a transfer tube that extends through the center of the cylinder's piston and terminates within a hollow ported section of a piston rod. The cylinder head can additionally include two electrically-actuated pilot valves and two pilot-operated check valves. The pilot-operated check valves include structure that, in combination with passages in the cylinder head, cause both pilot-operated check valves to open when pressurized fluid is being directed to one of the pilot-operated check valves by the main control valve.

Abstract: A hydraulic control circuit for a hydraulic actuator, including a high-low pilot valve having a sensing port for connection to a flow line. A single pressure line connects the high-low pilot to a hydraulic actuator. A second line connects the high-low pilot to a reservoir. A normally closed relief valve is connected to the single pressure line for relief of excessive pressure. A normally closed override valve is connected to the single pressure line for manual override of circuit controls. A pump is connected to the single pressure line for pressuring the single pressure line. The hydraulic control circuit has a normally open time out valve on the single pressure line, the time out valve being set to close a pre-set time interval after being manually activated, to isolate the high-low pilot, from the single pressure line to the hydraulic actuator, until the time out period has elapsed. The override valve is connected to the single pressure line between the time out valve and the hydraulic actuator.

Abstract: Herein is provided an improved proportional fluid control valve. The proportional valve includes a fluid valve that controls the flowrate of an output fluid. The fluid valve is coupled to a pressure chamber of the control valve. The position of the fluid valve, and the corresponding flowrate of the output fluid, can be varied by changing the pressure of a working fluid within the pressure chamber. The pressure within the pressure chamber can be increased by a piston that pumps working fluid from a reservoir to the chamber. The piston is coupled to a first solenoid and a spring that move the piston in a reciprocating pumping motion. The pressure of the working fluid within the pressure chamber can be decreased by opening a bleeder valve that allows working fluid to flow from the pressure chamber back to the reservoir. The bleeder valve is coupled to a second solenoid and a spring that open and close the valve.

Abstract: An operating arrangement for movable parts on motor vehicles, especially for trunk lids, folding tops and the like, consists of at least one hydraulic cylinder with a piston rod as the driving means which acts on the movable part either directly or indirectly, e.g., via a hinge, and at least one pump arrangement (7 through 11) mounted on the hydraulic cylinder with a tank, motor, and the like.

Abstract: A pump assembly comprises a hydraulic fluid pump having a housing assembled from a plurality of housing components that are pinned together rather than being clamped together by bolts. The pump is disposed in a cavity in a valve block so that the outlet fluid pressure from the pump is applied axially to the housing components to create a greater external axial force on the pump components than the internal axial force and thereby maintain the housing components in tight, sealing relation without the need for clamping bolts or other clamping means.

Abstract: Disclosed is an apparatus for a derrick, including hydraulic piston/cylinder arrangements for raising and lowering a yoke travelling on guide rails attached to the derrick. A hydraulic system having different modes of operation is provided for the operation of the piston/cylinder arrangements. The hydraulic system can operate in a normal mode for raising or lowering the yoke and in other modes by interconnecting upper and lower chambers of the piston/cylinder arrangements and utilizing a differential surface area of the piston exposed to the two chambers for rapidly raising or lowering the yoke.

Abstract: A hydraulic device includes a housing and a bulkhead disposed in the housing. A pump piston is provided in the housing and has first and second end surfaces with the second end surface of the pump piston and surfaces of the housing and of the bulkhead defining a pumping chamber. The pump piston is constructed and arranged to move within the housing to develop pressure on fluid in the pumping chamber. The first end surface of the pump piston and surfaces of the housing define a pump reservoir chamber. A ram piston is provided in the housing and has first and second end surfaces with the first end surface of the ram piston and surfaces of the housing and of the bulkhead defining a drive chamber. Connecting structure is associated with the bulkhead to communicate the pumping chamber with the drive chamber so that fluid pressure developed in the pumping chamber may be exerted on the first end surface of said ram piston. A barrier is provided in the housing between an end of the housing and the ram piston.

Abstract: A hydraulic power unit for an auto-hoist lift having improved noise characteristics and a more compact design. A motor and pump driving the power unit are located inside a hydraulic fluid reservoir to thereby reduce the amount of noise reaching the immediate vicinity of the power unit. The motor and pump are submerged in the hydraulic fluid to advantageously utilize the hydraulic fluid to cool the motor. The power unit may further incorporate a delay valve for reducing the start-up torque load on the motor, thereby allowing the motor to be sized for normal operating requirements rather than oversized for start-up requirements.

Abstract: The hydraulic device for raising and lowering seat of the barber's chair has a main housing section and a lower section. A sliding plunger is slidably mounted in a sleeve extending between the lower section and the top cover of the main housing section. An oil pump is operative to force the oil contained with the main housing section into a channel in the lower section to the bottom of the sleeve for raising or lowering the sliding plunger. The seat of the barber's chair is mounted to the top of the sliding plunger. The joint between the lower section and the main housing section is permanently sealed with a metal compound by welding, brazing or soldering.

Abstract: A firewood splitting machine is composed of a support frame, a cutter mounted on one end of the support frame, an oil pressure cylinder mounted on another end of the support frame, and an oil injecting device mounted in the support frame. The oil pressure cylinder consists of a cylindrical body, a piston, a rod member, a subsidiary piston, and a subsidiary rod member. The piston is located in the cylindrical body such that an oil pressure space is formed between the piston and a rear end cover of the cylindrical body. The rod member is fastened at one end thereof with the piston such that another end of the rod member is jutted out of a front end cover of the cylindrical body. A pivoting hole is extended along the direction of the longitudinal axis of the rod member such that the pivoting hole is in communication with the oil pressure space.

Abstract: A hydraulic system includes a hydraulic fluid pump, a hydraulic cylinder, and a pressure accumulator. A hydraulic fluid valve is movable between a first position and a second position. In the first position, the valve directs fluid from the pump outlet to the hydraulic cylinder and from the accumulator to the pump inlet. In the second position the valve directs fluid from the pump outlet to the accumulator and from the hydraulic cylinder to the pump inlet. In this way pressurized hydraulic fluid from the cylinder can be stored in the accumulator for reuse. The pump includes high pressure seals at both ends of the driven shaft in order to reduce or eliminate offset forces of the type that might increase friction and wear.

Abstract: An oil cylinder has a valve body, an oil pressure chamber, and an oil storage chamber. A shaft extends from the oil pressure chamber. The valve body has a piston chamber, an arc-shaped through hole, an enlarged hole receiving a rotating post, a first oil passage, a second oil passage, a third oil passage, a fourth oil passage, an oil hole, a first channel, and a second channel. A piston is disposed in the piston chamber. A trip lever passes through the arc-shaped through hole. The trip lever is connected to the rotating post. A big ball is placed in the third oil passage. A small ball is placed in the second oil passage. A compression spring is connected to the bolt and the big ball. A coiled spring is connected to the big ball and the small ball. A swivel rod is connected to the rotating post. A V-ring oil seal encloses the piston. An oil relief device is disposed on the valve body and inserted in the first channel.

Abstract: A portable one-hand-operable, hydraulic punching machine is disclosed which comprises at least two pumps driven by an electric motor, and a single-acting, spring-return cylinder driven by one of the pumps for a variety of punching operations such as cutting, perforating, and wrenching. The machine has a pump housing and a cylinder housing disposed end to end, with a partition therebetween in which there are formed a fluid supply passageway for supplying a hydraulic fluid under pressure from one pump to the cylinder fluid chamber, a fluid return passageway for returning the fluid from the cylinder fluid chamber to the pump fluid chamber, and a spool chamber open to the return passageway. In order to hold the return passageway closed during cylinder extension, and to open the same for cylinder contraction a return valve is provided which includes a spool reciprocably received in the spool chamber.

Abstract: In an electric lift truck, an asynchronous electric motor, a reversible sealed pump driven by the motor, communicating with the hydraulic actuators and also with a reservoir, a device which measures the angular position and the angular velocity of the motor, and a control and monitoring unit which causes the motor to be supplied according to the required speed of raising and lowering of the load support and on the basis of data supplied by the measuring device are used for raising and lowering the load support by means of one or more hydraulic actuators. There is a saving of energy in raising; there is also a recovery of energy in lowering, in which the motor acts as a generator to recharge the accumulator batteries of the lift truck.

Abstract: An electrohydraulic tilting device for a vehicle with a tilting cab has a pump, an electric pump drive motor connected by way of an electrical connecting line to a source for electrical energy, and a hydraulic piston/cylinder unit connected to the pump. The piston/cylinder unit is designed for exerting a force which is capable of tilting the cab forward and back. An overcurrent protection device is provided which is designed for automatic interruption and subsequently maintaining the interruption of the electrical power line of the pump motor when the electrical power taken up by the pump motor for a predetermined period exceeds a first threshold value which is higher than the maximum electrical power required during normal tilting of the cab. The overcurrent protection device is provided with manual reset means for ending the interruption of the power line.

Abstract: An actuating device for a coupling of an automatic transmission of a vehicle includes a housing and at least one piston slide positioned in the housing for pumping a pressure medium to a coupling element. At least one piezo element is positioned in the housing and acts on the at least one piston slide for displacing the piston slide from a neutral position in a reciprocating displacement direction within the housing.

Abstract: A rest portion is used to support a load at an adjustable height relative to a base which is connected to the rest portion by a pivotal linkage. A hydraulic ram coupled to a gas spring cylinder applies a spring force between the linkage and the base, the geometry of the linkage and ram being such that the upward component of spring force is invariant with respect to height adjustment. A control valve allows the ram to be locked at a selected height and the spring force provided by the gas spring is adjustable by movement of a second piston within the gas spring cylinder to vary the available volume of gas. A hydraulic pump is used to supply hydraulic fluid to the cylinder for adjusting movement of the second cylinder. The apparatus is suited for use in a chair-bed enabling a patient to be supported at an adjustable height during medical treatment.

Abstract: A portable punching machine is disclosed which has a hydraulic, single acting, spring return cylinder for linearly moving a punch toward and away from a die. The cylinder is driven in turn by a hydraulic pump disposed in a fluid chamber built into the machine. The pump fluid chamber is in constant communication with a fluid control chamber accommodating an elastic air bag capable of contraction and expansion for keeping constant the amount of hydraulic oil in the pump fluid chamber. Characteristically, a spacer of polyurethane foam or like elastic material is loosely inserted in the air bag in order to prevent the mutual contact of the inside surface of the bag, such contact being undesirable because the inside surface of the bag is customarily covered with a sticky parting agent that has been used in molding the bag from rubber.

Abstract: A flow control valve that has a solenoid operated pump that moves a poppet between an open and a closed position. The valve has a housing with an inlet, an outlet and a housing chamber that can allow fluid to flow from the inlet to the outlet. The poppet is located within the housing chamber and is adapted to move from an open position to a closed position, to control the flow of fluid through the valve. Attached to the poppet is a pump that has a first pump chamber separated from a second pump chamber by a wall. The wall has a first one way valve that allows fluid to flow from the second chamber to the first chamber. The second chamber has a diaphragm attached to a solenoid. The solenoid is provided with a series of energizing pulses that move the diaphragm and cause the second chamber to expand and contract. The pumping action of the second chamber causes fluid to flow into the first chamber. The first chamber thereby expands and moves the poppet into the open position.

Abstract: An hydraulic system has an hydraulic cylinder connected to a reversible pump by a first fluid line. A check valve assembly is connected in the first line and in a second line extending from the pump to a tank. The check valve assembly has a ball that seats on a conical valve seat to enable flow of fluid from the pump to the cylinder but to prevent flow in the opposite direction. A shuttle member in the check valve assembly is displaced by fluid pressure in the second line when the pump is reversed to unseat the ball and allow flow from the cylinder in the opposite direction via the pump to the tank.

Abstract: A hydraulic lift apparatus for a battery driven lift truck includes a hydraulic lift cylinder. A hydraulic pump operates as a pump in a load raising mode, so as to feed pressure fluid to the lift cylinder. The hydraulic pump operates as a motor in a load lowering mode. The hydraulic pump is driven by the pressure fluid displaced by the lift cylinder. A direct current machine is coupled to the hydraulic pump, so as to operate as an electric motor in the load raising mode and to operate as a generator in the load lowering mode. A useful brake circuit is energized by the direct current machine in the load lowering mode. A valve assembly is disposed in the pressure fluid path between the lift cylinder and the hydraulic pump. Control apparatus are provided for controlling the valve assembly and including speed regulating apparatus for varying the speed of the direct current machine. At least one secondary hydraulic consumer is adapted to be connected to a hydraulic pressure source via an associated control valve.

Abstract: A driving device comprises a source of hydraulic fluid under pressure, a working arrangement (6) having a working chamber (7) intended for receiving hydraulic fluid and a working member (8) adapted to be put in motion on respective fluid supply to and fluid evacuation from the working chamber. Conduits (20, 29, 30) are provided for respective supply to and evacuation from the working chamber (7) of hydraulic fluid. A valve (16) is adapted to, in a first state, direct fluid to the working chamber and, in a second state, allow evacuation of fluid from the working chamber. An apparatus (17) are provided for returning the working member to a starting position. These apparatus comprise an ejector arrangement adapted to generate a negative pressure evacuating the working chamber as a consequence of flow of fluid through the ejector arrangement. The hydraulic fluid source is constituted by a high pressure washing unit known per se or of an arbitrary nature.

Abstract: A linear hydraulic actuator has a reciprocating pump which provides pressurized hydraulic fluid contained in a reservoir to a hydraulic cylinder in which slides a piston which supplies the actuator output. A diverter valve in flow communication with the pressurized hydraulic fluid has an adjustment shaft allowing manual adjustment of the rate of flow of pressurized hydraulic fluid to the cylinder. Preferably the pump is immersed in the hydraulic fluid held by the reservoir, and the adjustment shaft of the diverter valve penetrates a wall of the reservoir to allow external adjustment of the diverter valve.

Abstract: A hydraulic jack safety valve structure provided within the one-way valve body of the jack. The one-way valve has a cylindrical shape and is provided on the pump base of the jack. An annular slot is provided in the cylindrical body. The annular slot is provided with an oil inlet port and an L-shaped oil inlet passage which extends from the top surface of the one-way valve. An oil discharge port is provided so that the top of the one-way valve communicates with the bottom. The wall of the annular slot is provided with a safety oil discharge port which communicates with the oil discharge passage. Inside the safety oil discharge passage, a push pin and a safety spring are inserted in proper sequence. An adjustment screw is used to secure the pin and spring in place. The push pin, inside the safety oil discharge passage, provides flow guidance so that the flow of the hydraulic discharge fluid can be smooth.

Abstract: A filter arrangement for a single acting, telescopic, hydraulic cylinder, useful to raise and lower a dump truck bed, is configured for installation in one line of a two-line dump pump to filter only hydraulic fluid returning to sump. This is accomplished by a first one-way check valve which blocks fluid flow through a filter element toward the hydraulic cylinder but allows fluid flow from the hydraulic cylinder to sump and a second one-way check valve, disposed in parallel with the filter element, to block flow to the sump from the hydraulic cylinder while allowing flow from the sump to the hydraulic cylinder so that returning hydraulic fluid passes through the filter element. Preferably the filter element is disposed in a spin-on filter assembly which includes the one-way check valves integral therewith.

Abstract: A single rod three chamber fluid cylinder is driven in an initial rapid advance forward stroke by a main pump, pumping fluid through a proportional directional control valve to act against a first equal area at the head end of the piston. Fluid expelled from a second equal area at the rod side of the piston is returned to the reservoir through a proportional directional control valve which is in a first position while a two position valve is in its first position allowing an accumulator to fill a third chamber exposed to a third area of the head side. When shifting to the feed stroke, the two position valve switches to its second position disconnecting the accumulator to the third area and connecting the main pump to the third area while also connected to the first equal area. Upon the return stroke of the piston, the fluid from the first equal area is returned to the sump and the fluid from the third area is routed to the accumulator.

Abstract: A hydraulic lift device for battery operated industrial trucks comprising a hydraulic ram, a hydraulic machine operating as a pump in a load raising cycle and as a motor in a load lowering cycle, a separately excited DC machine operating as a motor in the load raising cycle and as a generator in the load lowering cycle, and energy recovering circuitry which is fed by the DC machine in the load lowering cycle. A load holding valve is disposed in the fluid path between the hydraulic ram and the hydraulic machine. Speed of the DC machine is set by a speed control. A separate field current control includes a desired value setting circuit for determining a desired value for the field current (I.sub.FSoll) from a predetermined relationship between the speed (n.sub.Ist) and the armature current (I.sub.ASoll). Power switches are associated with the field winding and the armature, and are actuated by the current control.

Abstract: A plastic reservoir adapted for use with a hydraulic power pack. The reservoir includes a plastic body and a substantially plastic mounting ring which is joined to the plastic body of the reservoir. The mounting ring includes a metal reinforcing ring which is encapsulated in the plastic portion of the mounting ring.

Abstract: A hydrostatic power steering system is provided of the type including a steering control unit (3) operated by an input such as a steering wheel (1) to control flow from a source (8) to a steering cylinder (7). The source is operated in response to an electrical signal from a controller (82), controlled by a sensed pressure at a pressure detection port (64). The pressure at the port (64) is communicated from the main fluid path of the steering control unit (3), downstream of the fluid meter (18) when the spool (21) and sleeve (22) are relatively displaced. In systems in which the system reservoir (R) is at an elevated ("regulated tank") pressure, the pressure detection circuit is drained through a variable orifice (70) to a drain port (66), which is in communication with a sump (S) maintained at substantially atmospheric pressure. As a result, the steering system responds at a lower steering pressure, and the initial steering is smoother.

Abstract: A tilt/trim device for an outboard engine mounted on a transom of a marine vessel includes a stern bracket adapted to be fixedly mounted on the transom, a swivel bracket pivotally supported on the stern bracket, the outboard engine being adapted to be mounted on the swivel bracket, a hydraulic cylinder/piston unit for vertically swinging the swivel bracket with respect to the stern bracket, the hydraulic cylinder/piston unit having one end pivotally coupled to the stern bracket and an opposite end pivotally coupled to the swivel bracket, and a hydraulic circuit hydraulically connected to the hydraulic cylinder/piston unit, for extending and contracting the hydraulic cylinder/piston unit.