Abstract: A proportional directional control valve in combination with a pressure compensator flow rate control valve opening towards a reservoir and a pressure unloading valve in the load- pressure- carrying control line for the compensator valve are provided to actuate the telescopic cylinder of a tipper truck. The valve device is connected to a pump of constant displacement. The operating speed of the telescopic cylinder is independent from the load to be lifted and the driving speed of the pump. Upon reaching a predetermined load pressure the pressure unloading valve is activated and the load pressure engaging the compensator valve towards closing direction is reduced via the reservoir such that the compensator valve opens and the pump displacement volume returns to the reservoir.

Abstract: A valve for use in a hydraulic compression tool. The valve has a frame with a central chamber, a first inlet, a second inlet and a discharged outlet. A first gate is located at the first inlet. A plunger assembly having a first plunger member and a second plunger member are movably mounted in the central chamber with a spring biasing the plunger member against the second plunger member. The second plunger member has a conduit between the second inlet and the first plunger member. The valve has a first home position that substantially prevents fluid from flowing therethrough. The valve has a second manual release position wherein fluid can flow into the first inlet and out the discharge outlet. The valve also has a third automatic relief position such that in the event a predetermined maximum fluid pressure is exceeded a gate will open between the first plunger and the second plunger member to allow fluid to flow from the second inlet through the valve and out the discharge outlet.

Abstract: A pump lever for a jack is disclosed which comprises a protrusion formed near a plunger of a fluid pump for the jack; a handle sleeve having a first end and a second end, the first end being adapted to receive a handle and the second end being pivotally joined at said protrusion by a first pin, and in addition, a certain position between the first and second ends of the handle sleeve being pivotally joined with the plunger by a second pin; and a torsion spring having a pair of counteraction portions and a loop portion shaped between said pair of counteraction portions, the loop portion being passed through and supported by the first pin, and the pair of counteraction portions being adapted to respectively make contact with the protrusion and the second pin so that the torsion spring will urge the handle sleeve to raise to its uppermost position when one frees the handle, the top end of which is received in the first end of the handle sleeve at a lowered position.

Abstract: An attachment and method to implement loading of a vehicle having a hinged storage compartment closure member such as a trunk lid or hatchback on an automobile by utilizing the closure member as a lifting lever. The conventional hinged trunk lid or hatchback is formed with one or more hook or other material engaging members at the free end of the lid or hatchback remote from the conventional hinge mounting edge of the lid or hatchback. A piston-cylinder assembly having fixed capacity energy storing means in the form of a fixed charge fluid chamber and a variable capacity energy storing means in the form of a variable charge fluid chamber is positioned between the vehicle body and the lid or hatchback, and fluid from a fluid system is selectively directed to the variable charge fluid chamber in the cylinder to displace the piston against the trunk or hatchback lid to lift same, whereby any material engaged by the hook can be lifted to a position over the vehicle storage compartment.

Abstract: A vehicle barricade comprises a frame to which a barrier plate is pivotally mounted for being moved between a passage and a blocking position. First and second hydraulic motors operably interconnect the plate and the frame. An hydraulic power supply is operably connected with the hydraulic motors and includes an uninterrupted line for assuring constant power supply to the first hydraulic motor for thereby biasing the first hydraulic motor into extension and control valve means for selectively supplying power to the second motor for thereby causing selective pivoting of the plate.

Abstract: Disclosed is a piston-stroke adjusting mechanism of a hydraulic tool comprising an oil tank, a ram for causing the forced feed of an oil, and a piston permitted to slide by the pressure of a working fluid. The piston is formed with a through bore into which an adjust pin is slidably inserted in a manner that an end thereof is directed toward the bottom of a cylinder. The piston is rotatably mounted with an adapter at its head section. The adapter has a small-diameter portion at one side thereof which is located in the through bore to be connected to the adjust pin.

Abstract: The present invention is a hydraulic hand-tool which includes an elongate piston having at least two sections of different transverse cross-sectional areas, a housing including a hollow front end portion having an interior surface defining a plurality of sections with different inner diameters corresponding in size, position and number to accommodate the sections of the piston in a manner which permits the piston to slide in a reciprocating manner within the hollow forward end of the housing and to define a main chamber and at least one auxiliary chamber for receiving hydraulic fluid as the piston slides in a forward direction; an hydraulic fluid conduit having a primary line with an end opening directly into the main chamber and at least one supplemental line communicating with at least one of the auxiliary chambers after the piston slides in a forward direction a predetermined distance; an hydraulic fluid or reservoir adapted to supply hydraulic fluid to another end of the primary line; and a pump in commun

Abstract: A system of hydraulic tools utilizing removably, replaceable and substantially interchangeable valve assemblies, fluid reservoirs and hydraulic driving mechanisms. The fluid reservoir maintains the hydraulic fluid under moderate pressure. The valve assembly can contain a hydraulic pump for powering the driving mechanism. The hydraulic pump preferably has displacement varying means for changing the power transfer ratio of the pump. The hydraulic assemblies are removably received in a variety of tool bodies.

Abstract: A hydraulic control system for an elevator or other similar reciprocating user is disclosed, which comprises an adjustable throttle valve and a control or bypass valve disposed in the fluid supply line between the pump and elevator. A pressure difference balance is provided for controlling the operation of the control valve, and the pressure difference balance has one end operatively connected to the pressure provided by the pump, and the other end operatively connected to the pressure in the user or load line. The control valve is thus adapted to maintain a desired pressure difference across the throttle valve which is independent of the load on the user. In addition, the zero setting of the pressure difference balance is adjustable, so as to permit the system to be equally operable in both the upward and downward movements of the elevator.

Abstract: A hydraulic intensifier having a hydraulic motor driven from a low pressure source and operable to drive a low pressure pump for sucking oil from a reservoir and for delivering the oil as charge oil to a high pressure pump. The latter also is driven by the hydraulic motor and pressurizes the charge oil so as to deliver oil at high pressure to a hydraulic actuator. The intensifier is of a self-contained and modular construction and includes a case which defines the oil reservoir and which is closed by detachable end caps permitting the motor and the low pressure pump to be pulled out of one end of the case and permitting the high pressure pump to be pulled out of the other end of the case.

Abstract: A hydraulic apparatus for converting hydraulic pressure into mechanical movement for operating a tool or other device, operated by a pump block having a bore therein and a moveable plunger disposed within said bore. A cylinder is disposed over the pump block. The cylinder is captively held over the pump block and is moveable with respect thereto along the common axis. A fluid reservoir is defined between the cylinder and the pump block, and contains the hydraulic fluid. The plunger is operated by a pair of moveable arms secured to the apparatus and causes pressure to build in the fluid in an inlet chamber which communicates between the pump block and the cylinder. A pressure control valve is mounted adjacent the pump block and limits the hydraulic pressure which may be applied in the system. A release valve and apparatus is provided for releasing the hydraulic pressure and returning it to the reservoir.

Abstract: A piston sealed by a rolling membrane is arranged in a cylindrical housing comprising two components and this piston translates against the force of a return spring. A vibrating armature pump driven via two wires by a variable alternating voltage serves for operating the positioning drive. The vibrating armature pump draws hydraulic fluid from a reservoir chamber through an inlet opening and transports the hydraulic fluid through a return valve and through a first orifice into a pressure chamber. The piston is displaced downwardly conjointly with a piston rod. The pressure generated by the vibrating armature pump is dependent upon the applied voltage. A state of equilibrium between this pressure and the counterpressure of the spring arises such that the positioning drive is suitable for continuous control or regulation operations.

Abstract: A hydraulic power source has a main body with a valve body and a valve assembly disposed in it. A reservoir and pump body assembly is connected to a top surface of the main body, and a hydraulic piston/cylinder assembly is connected to a bottom surface of the main body. A hydraulic circuit connects the various elements for fluid flow. The hydraulic power source is compact and can be located remotely on, for example a vehicle, at a point near an object or part to be moved.

Abstract: The jack comprises a fixed jaw, rigidly associated with the jack body, and a movable jaw facing said fixed jaw and being connected to a piston sealingly movable inside a cylindrical chamber. In the body, first and second chambers are provided, respectively in communication, through a first delivery conduit and first intake conduit, and through a second delivery conduit and second intake conduit, with the cylindrical chamber and a working fluid reservoir, in the first chamber there being sealingly movable a high pressure piston, whereto is connected a lug passed through the second chamber in sealed relationship therewith, wherein it acts by contact on an elastically biased low pressure piston, the high pressure piston being connected at the free end thereof to an actuating lever handle.

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: A hydraulic amplifier having a hydraulic motor adapted to drive a high pressure pump for boosting the pressure of low pressure fluid and for supplying high pressure fluid to a hydraulic actuator. The motor also drives a scavenging pump for overcoming high back pressure in the return side of the system. The amplifier is controlled by two valves which may be actuated by manually operating a single lever.

Abstract: Discussed herein is a rapid actuating device for a hydraulic actuator utilizing two or more relief valves to control the hydraulic flow of the actuator for various loading or no loading conditions in order to speed up the required operation time.

Abstract: A multipurpose, hydraulically actuated apparatus comprising a piston movable in response to fluid under pressure within walls defining a piston chamber. Actuating fluid is supplied to the piston chamber by a uniquely constructed hand operated fluid pump. The area of the fluid impinging surface of the piston is in multiples of one inch. Accordingly, when the apparatus is used as a hydraulic scale the weight being lifted by the piston can be read directly on a pressure gauge which is calibrated in pounds per square inch and which is connected to the piston chamber below the piston.The apparatus can readily be converted to function as a cutting device by connecting a U-shaped member to the walls of the unit and by connecting a cutting element to the outer face of the piston. The U-shaped member includes spaced apart arms and a bight portion defining a closed space adapted to encircle the nut which is to be cut.

Abstract: A hydraulic pump and valve unit is disclosed which is particularly useful in a system using a hydraulic cylinder for raising and lowering the cab of a truck. The unit includes a pump which is connected to a valve intake chamber which, in turn, opens axially into a flat end of a larger valve chamber. An annular thrust seal is slidably mounted in the valve intake chamber, and spring means biases the thrust seal against the flat end of a valve spool which is rotatably mounted in the valve chamber. The valve spool has a pair of flow passages therein which connect respective ports in the flat end of the valve spool with corresponding ports in the cylindrical surface of the valve spool. The ports in the cylindrical surface of the valve spool register with a second pair of cooperating flow passages which deliver hydraulic fluid under pressure from the unit to a system such as a hydraulic cylinder, and return hydraulic fluid from such system to the unit.

Abstract: A pressure-fluid supply system for use in a hydraulic loader device. Included in the device are a mast mountable on a truck, a platform rotatably mounted on the upper end of the mast, and hydraulic fluid-operated equipment carried on the platform for rotation therewith. The supply system includes a pump anchored on the platform, for supplying hydraulic fluid to the equipment carried thereon, and an engine mounted on the mast. The engine's power output is drivingly coupled to the pump about the platform's axis of rotation, wherein the platform may be rotated endlessly during pump operation.

Abstract: A slow-opening valve including a main valve, a chamber for receiving a control fluid other than that controlled by the main valve, and a member within the chamber responsive to the volume of control fluid in the chamber for opening and closing the main valve. A solenoid pump, including an armature and an electrical solenoid for vibrating the armature, produces fluid flow in small increments with respect to the chamber to effect opening of the valve. An auxiliary valve, which opens and closes in response to the position of the solenoid pump armature, controls flow of fluid with respect to the chamber for closing the main valve.

Abstract: An arrangement for modifying a plow blade power unit of the type positioned between the mounting frame on the front of a vehicle and a plow blade lift arm, to a unit for creating pressurized fluid from a remote location. Modification enables a basically similar power unit to be utilized in both remote and direct operational environments with only minor substitution of interchangable parts. A piston-cylinder unit which enables direct lifting of a plow blade is replaced by a modified, but similar, cylindrical element for use in indirect lifting of a plow blade by fluid under pressure.

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: A single hand held and operated tool comprising a housing; a hydraulic fluid reservoir located in the housing; a hydraulic pressure cylinder located in the housing; a hydraulic piston moving with respect to the pressure cylinder in response to hydraulic pressure produced therein; a hydraulic pump operable by a single hand while grasping the housing and coupled to the fluid reservoir and to the pressure cylinder for forcing hydraulic fluid received from the reservoir into the cylinder; and valve apparatus governing fluid communication between the hydraulic pump and the pressure cylinder and operative in response to hydraulic pressure in the cylinder for lowering the quantity of hydraulic fluid supplied to the cylinder by each pump stroke when the pressure in the cylinder exceeds a predetermined pressure, thus providing two-speed tool operation.

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 readily portable hydraulic power source for supplying hydraulic fluid pressure to emergency hydraulic tools is foot-operated such that the operator's hands are left free to use the hydraulic tools and both the tools and power source may be operated by a single person. The power source includes a generally planar base member, a hydraulic pump fixedly mounted at one end of the base member, a foot-engaging planar member in generally overlying relation to the base member, a hinge connecting ends of the base member and the planar member for movement of the planar member relative to the base, and a resilient spring between the base and planar members to urge the members pivotally apart upon release of pressure from the operator's foot. The operator's foot is retained by straps and a heel retaining portion attached to the planar member, with the heel portion having an arm operatively connected to a hydraulic piston of the pump.

Abstract: A servo controlled, proportional valve is connected in parallel with a forklift truck control valve to regulate the speed at which the fork is raised or lowered by shunting the forklift pump output to the hydraulic fluid reservoir during the raising of the fork and by restricting the return flow of fluid from the lift jack during lowering of the fork with the setting of the proportional control valve being servo controlled in response to a fork height sensor.

Abstract: A control circuit for a hydraulic cylinder and shaft assembly to regulate movement of the shaft relative to one end of the cylinder. The circuit has a fluid pressure supply and associated reservoir and a metering valve with interconnected normally closed passage means connected at one end to the one cylinder end and at an opposite end to the reservoir. The fluid pressure supply, in a first condition, supplies fluid under pressure to the one cylinder end, and, in a second condition supplies piloting fluid under pressure for actuating the metering valve to regulate the fluid flow from the one cylinder end to the reservoir through the normally closed passage means.

Abstract: The specification discloses a hydraulic pressure operated emergency hand tool of the type in which manual pressure exerted on an all position small-area pump piston creates a hydraulic pressure which is communicated to a power cylinder for activating a plural jaw tool member, such as a pair of cutter blades. The jaw members are pivoted together intermediate their ends and one end of each is pivotally connected one to the power cylinder opposite the free end of the piston and the other to the free end of the piston. A release valve provides instant return displacement of hydraulic medium via a by-pass communication from the cylinder to the reservoir to relieve the activating pressure on the cutter blade and restore it promptly to normal position. Interchangeable tool members are provided.

Abstract: A work vehicle having a work arm assembly mounted for horizontal oscillation on a swivel platform. The arm assembly and the swivel platform are actuated by separate hydraulic actuators. The two actuators are connected in parallel with one another to a control valve via a circuit selection valve. The arrangement enables the swivel platform and the arm assembly to move in the same direction by operating the control valve.

Abstract: A hydraulic valve system particularly adapted for controlling a hydraulically powered elevator. The system involves essentially a bypass valve which selectively bypasses hydraulic fluid from the pump directly back to the tank during the up mode operation, thereby controlling the up speed of the elevator; and a down valve which selectively controls the escape of fluid from the elevator jack back to the tank, thereby controlling the down speed of the elevator. The down valve also serves as a check valve for retaining fluid pressure in the jack. Both the bypass valve and the down/check valve are each controlled by closely integrated cylinder-and-piston arrangement, with pressure to the cylinder being controlled by a control valve structurally interlinked to the respective piston. The bypass valve also serves as a check valve between the jack and the tank during the down mode of operation. The cylinder-and-piston control for the bypass valve makes possible an initial limit opening of the bypass valve, i.e.

Abstract: A single-hand operated tool comprising: first and second relatively movable elements adapted to be associated with a head assembly for application of pressure to a workpiece; a housing; a hydraulic pump disposed within the housing; hydraulic fluid communication means associated with the pump for exerting hydraulic force on the relatively movable elements; articulated lever means associated with the pump and arranged such that reciprocal motion of the lever means provided by the action of a single hand, unassisted, operates the pump and produces a desired force on the workpiece; release valve means for releasing the force exerted by the hydraulic fluid in response to a manual actuation produced by the single hand and including a valve stem and seat wherein the force urging seating of the valve stem against the valve seat is smaller than the desired force.

Abstract: A power assembly for supplying power to a hydraulic piston and cylinder unit for raising and lowering an elevator car. The power assembly may comprise: a hydraulic fluid reservoir; a hydraulic pump assembly, the intake of which is connected to the reservoir and the outlet of which is connected to the piston and cylinder unit; and a control valve disposed above the hydraulic reservoir for controlling the flow of fluid to and from the piston and cylinder unit.

Abstract: For tractors or like machines which can be provided, upon assembly, with either a hydrostatic transmission or a mechanical stepped-speed transmission, a transmission housing having a removable cover is provided. The machine has a drive shaft and a driven shaft and, according to the invention, a hydrostatic transmission is mounted intact upon the cover for introduction into and removal from the housing with this cover. The hydrostatic transmission comprises an inclined-disk variable-displacement pump whose input shaft is connected to the drive shaft and a hydraulic pump of the drive-flange type hydraulically connected to the pump and having an output shaft which is, in turn, connected to the driven shaft.

Abstract: An improvement in patient lifting devices comprising an upright member, a boom pivotably mounted on the upright member, a fluid cylinder pivotably mounted between the upright member and the boom, and a manually operated pump for the fluid cylinder. The improvement comprises means actuated by the pump handle for transferring fluid from the fluid cylinder to a fluid reservoir, thereby permitting the boom to lower under the combined weight of the boom itself and anyone being carried by the boom.

Abstract: A windmill in which a propeller is directly fixed to the shaft of a rotary hydraulic pump mounted on a cylinder casing rotatably mounted about a vertical axis to the top of a tower. A piston in the cylinder is recicprocated by the hydraulic fluid expelled by the pump to power a reciprocal pump at the base of the tower to which the piston is attached by a lift rod. The piston is fitted with a valve which permits the piston and attached lift rod to freely move on the downstroke through the fluid in the cylinder, with the valve closed during the upstroke of the piston to permit the pressurized fluid below the piston to raise the piston and lift rod.

Abstract: The unit comprises outer and inner coaxial cylinders defining an hydraulic fluid reservoir between the inner walls of the outer cylinder and the outer walls of the inner cylinder. The opposite ends of the cylinders are closed off by a lower closure means and an upper cylinder head. A single piston within the inner cylinder has first and second piston rods extending from opposite sides through the cylinder head and lower closure. The cylinder head includes an hydraulic pump with passages placing the reservoir into communication with the interior of the inner cylinder above the piston together with appropriate check valves so that operation of the hydraulic pump will move the piston down the inner cylinder to exert a pulling force on the first piston rod and a pushing force on the second piston rod.

Abstract: An hydraulic pump comprising a plunger slidingly located within a housing. A first valve is adapted to allow fluid to be drawn from a reservoir into the housing during movement of the plunger in one direction, and a second valve is adapted to allow fluid to flow from the housing during the greater part of movement of the plunger in its other direction. A control apparatus is provided to control the second valve at or near the completion of the plunger's movement in the mentioned other direction to allow fluid to move back through the second valve and into the reservoir.

Abstract: Air operated hydraulic pump apparatus disclosed is particularly adaptable for use with tilting cab control systems. Reciprocation of a pump plunger to pump control liquid from a reservoir is achieved by a spring biased piston slidable within a cylinder bore and alternately moved in opposite directions by the spring bias and compressed air. A valve of the apparatus has a first position where it supplies compressed air to a first chamber of the cylinder bore so as to act against the spring bias and move the piston in one direction. The spring providing the bias is received within a second chamber of the cylinder bore and moves the piston in the opposite direction when the valve is moved to a second position that terminates the supply of compressed air to the first chamber and exhausts the first chamber to the environment.

Abstract: A swivel mounted pump apparatus for a mine crane is provided having an integral fluid-flow control valve incorporated in the swivel mounting structure. The pump mechanism is a hand operated fluid pump which is mounted on an upright supporting spindle for selective swiveling movement to a desired operating position. Fluid interconnection of the pump mechanism to a fluid reservoir and actuating ram of the associated apparatus is achieved through internal passageways formed in the supporting spindle to permit operator control of fluid flow through the system. This valve may be selectively operated to enable either actuation of the ram by the mechanism or a reverse fluid flow in the system and to also provide protection to the apparatus from excessive fluid pressures that may build up through incorrect or improper use of the associated ram mechanism.

Abstract: Brake apparatus, particularly one in which the brake may be both actuated and released by a hydraulic force, held engaged by a mechanical force and in which a strong spring force, tending to restore the brake, prevails while the brake is held engaged; brake applying pressure, after the brake is engaged, is at first slowly released, hydraulic pressure employed to release the brake is maintained at a minimum value even though the brake may be released and certain conditions are sensed for coincidence before generating a signal indicating that the brake release conditions are complied with.

Abstract: A hydraulic vehicle jack including a novel release valve is disclosed. The jack is of the type having a high pressure cylinder, a ram partially extensible from and retractable into the cylinder, and a high pressure pump for forcing fluid from a reservoir into the cylinder to extend the jack. When it is desired to lower the jack, the release valve needle is turned so as to withdraw a needle tip from fluid-flow-halting engagement with a valve seat. This needle tip is formed in the shape of a cone having an altitude of a dimension greater than the cone base radius. When the needle tip is withdrawn from its position against the valve seat, a small but precisely defined fluid-flow-permitting orifice is created. Valve lowering action then occurs over an extended time period which permits the jack operator to precisely control or halt valve lowering action as desired.

Abstract: Presented is a hydraulic jack structure having a pump assembly in connection with which is rotatably mounted a pump handle assembly which may be rotated in a horizontal plane through about 320.degree. to permit selective positioning of the handle during a pumping operation.

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 closed-loop hydrostatic drive unit having a variable displacement fluid pump driven by an electric motor for generating high-pressure fluid adapted to be communicated to a fluid motor and returned to the fluid pump via a high-pressure filter. The closed-loop hydrostatic drive unit is mounted to a rectangularly-shaped reservoir housing having upper and bottom surfaces connected by side walls and end walls to define therein a chamber for the storage of fluid at a low pressure which is communicated to the fluid pump via a charge pump and suitable conduits and check valves. In a first embodiment of the invention the interior of the reservoir housing is divided by means of a partition to define the fluid-holding chamber, while the remaining portion of the reservoir housing defines a separate chamber for the mounting and storage of the high-pressure filter and/or other selected fluid power components.

Abstract: A hydraulically operated tool in which the working elements are operated by a ram and cylinder chamber assembly with the pumping unit for the tool being concentrically located within the ram and the hydraulic fluid reservoir being collapsible and contained in one of the tool handles.

Abstract: A compressed air generating device for forklift trucks in which a main pipeline connected to the end of the lift cylinder air chamber branches into a high-pressure air pipe and a return pipe, selectively communicating with the main pipeline through a switching valve means. With the main pipeline switched to communication with the main pipeline high-pressure air pipe, during the descending phase of the piston, air is sucked through an air suction pipe attached to the main pipeline into the lift cylinder air chamber, and during the rising phase of the piston, the air in the air chamber is compressed and is sent into an air tank as compressed air.

Abstract: Tilting cab control apparatus including a horizontally extending hydraulic pump reservoir cover plate having upper and lower surfaces and edge surfaces extending between the upper and lower surfaces to define the periphery of the plate. A pump reservoir having an upper opening is sealed against the lower surface of the cover plate such that the upper and edge surfaces thereof are exposed. A pump opening of the cover plate, a pump in the opening, a valve bore communicated with the pump opening, and a control valve in the valve bore cooperate to provide pumped hydraulic fluid to a tilting cab control cylinder. One embodiment of the cover plate is specifically designed for use with single acting cylinders while a second embodiment is designed for use with double acting cylinders.

Abstract: The invention relates to improved jack-pump devices comprising a pump with a sliding piston forming first and second pump chambers, one on each side, a jack with a sliding piston forming first and second jack-chambers, one on each side, a first valve between the pump chambers, acting unidirectionally from the second to the first pump chambers, a second valve between the first chambers of the pump and the jack, and a communication device between the second chambers of the pump and the jack, the pump and jack pistons being slidably mounted and axially aligned in the same body filled with fluid, a fixed transverse partition disposed in the cylinder body between the two pistons, and a plunger for compensating variations of volume, slidably mounted in one of the two second chambers, close to the corresponding extremity of the body.The main application is as a lifting device for regulating the height of members or parts of moving machines, of seats for chairs, vehicles, building stays, etc.

Abstract: A hydraulic circuit comprises a first tank elevated above a second tank and openly communicating therewith by a conduit adapted to continuously maintain the second tank at full capacity with a hydraulic fluid. The hydraulic fluid is pumped out of the second tank and to a work system wherefrom it is recircuited back through a filtering system, retained in the first tank. Upon malfunctioning of the filtering system to prevent the egress of hydraulic fluid therethrough, the increased pressure level of the recircuited hydraulic fluid will function to open a directional control check valve in the second tank to by-pass the conduit normally communicating hydraulic fluid from the first tank to the second tank.