Abstract: Three tandem drive units are provided. Outward variable volume working chambers at one end of the drive units are connected via passageways in the piston rods with inward variable volume working chambers at the opposite end of the drive units. In similar fashion, inward variable volume working chambers at the first ends of the drive units are connected to outward variable volume working chambers at the second ends of the drive units, also via passageways in the piston rods. At each end of the assembly, the piston rods pass through piston rod receiving openings in a cylinder head forming member. Each cylinder head forming member includes a manifold passageway and spool valves for controlling a sequencing movement of the drive units. The piston rods provide the spools for the spool valves.

Abstract: Three tandem drive units are provided. Outward variable volume working chambers at one end of the drive units are connected via passageways in the piston rods with inward variable volume working chambers at the opposite end of the drive units. In similar fashion, inward variable volume working chambers at the first ends of the drive units are connected to outward variable volume working chambers at the second ends of the drive units, also via passageways in the piston rods. At each end of the assembly, the piston rods pass through piston rod receiving openings in a cylinder head forming member. Each cylinder head forming member includes a manifold passageway and spool valves for controlling a sequencing movement of the drive units. The piston rods provide the spools for the spool valves.

Abstract: A dual hydraulic oscillator for the reciprocating cutter of an agricultural machine is provided. The dual oscillator has two pistons reciprocating in opposite directions and a single pilot valve, with resynchronization performed twice per cycle of the oscillator. Also provided is a single or dual hydraulic oscillator comprising a cylinder having first and second opposed ends. A reversing pilot valve is provided for controlling flow of pressurized fluid to at least one of the first and second cylinder ends. The pilot valve includes first and second pilot passages for controlling the reversing operation of the pilot valve. A piston reciprocates between first and second positions in the cylinder. The piston has an inner bore. The bore has first and second circumferential logic grooves. An inner logic mechanism is slidably received in the bore.

Abstract: A pair of control valve assemblies for alternately actuating a pair of fluid-driven free-piston devices by using fluid pressure communication therebetween. Each control valve assembly is switched by a pressure signal depending on the state of its counterpart's piston. The communication logic is arranged to provide overlap of the forward strokes of the pistons, so that at least one of the pair will always be pressurized. Thus, uninterrupted pumping of liquid is made possible from a pair of free-piston pumps. In addition, the speed and frequency of piston stroking is entirely dependent on the mechanical power load applied. In the case of a pair of pumps, this enables liquid delivery at a substantially constant pressure over the full range of flow rates, from zero to maximum flow. Each of the valve assemblies uses an intake-exhaust valve and a signal valve with the signal valve of one pump being connected to be pressure responsive to the piston of the opposite cylinder or pump.

Abstract: In a mechanism for extending or retracting a telescopic unit, the plurality of interconnected cylinders includes an extension passage, a retraction passage and a flow-through passage interconnected to provide a flow path of a retraction signal from the first to the last cylinder and sequencing means for transmitting the retraction pressure signal sequentially from the last cylinder to the first cylinder to initiate retraction from an extended position beginning with the last cylinder. A poppet control check valve provides a position sensitive means to transmit the retraction signal to the next cylinder in the cycle. The sequence control valves and hold loading valves were formed integral to each of the cylinders. The load holding mechanism prevents unintentional extension and retraction movement under the action of the load for each of the cylinders.

Abstract: A loading vehicle has a boom pivotally mounted thereon for movement in a vertical plane, the boom supporting a loading unit at its distal end. A fluid control system includes a boom cylinder for raising and lowering the boom, a loading unit cylinder for tilting the loading unit relative to the boom, a tank for holding fluid and a pump for selectively pumping fluid to the cylinders through manually controlled selector valves. The loading unit attitude is controlled by a system including a bypass valve, a flow splitting valve and a boom position detector for actuating the bypass valve. Fluid forced from a lowering chamber of the boom cylinder as the boom is raised is applied to the bypass valve. As long as the boom is in a position falling within a lower range of positions the boom position detector does not actuate the bypass valve and all fluid from the lowering chamber is diverted to the tank.

Abstract: A control valve assembly for alternately actuating a pair of fluid-driven free-piston devices by using fluid pressure communication therebetween. Each control valve is switched by a pressure signal depending on the state of its counterpart's piston. The communication logic is arranged to provide overlap of the forward strokes of the pistons, so that at least one of the pair will always be pressurized. Thus, uninterrupted pumping of liquid is made possible from a pair of free-piston pumps. In addition, the speed and frequency of piston stroking is entirely dependent on the mechanical power load applied. In the case of a pair of pumps, this enables liquid delivery at a substantially constant pressure over the full range of flow rates, from zero to maximum flow.

Abstract: An infinitely variable differential hydrostatic transmission utilizing a fixed displacement pump/motor and a variable displacement pump/motor interconnected with appropriate valving, to provide a mechanical/hydraulic differential drive which is capable of achieving an overall efficiency in the 98.degree.-99.degree. range. In the preferred embodiment, which utilizes axial piston type pump motors, pistons in multiples of four are utilized in order that each piston will have a piston located 90.degree. from it to serve as its control valve. The fixed and variable displacement motor/pump are provided as an integral unit containing bearing mountings, cylinder barrels, valve ports, piston seal mountings, hydraulic flow passages, pressure reservoirs and manifolding by forming a series of individual segments and sealing them together into a single structural unit. A unique mounting arrangement is utilized to positively attach the pistons to an anti-friction swashplate which eliminates all side loads on the piston.

Abstract: A low-impact drive unit operates by air under pressure. It includes aligned working and pressure chambers. The working chamber contains a working piston and a working piston rod extending from an end of the chamber. The pressure chamber contains a rear outer piston having a cylindrical recess and a central bore. An inner piston is located in the cylindrical recess and has a main piston rod extending through the bore, a bore in a separator separating the chambers, and is affixed to the working piston, so as to move together. The main rod has a longitudinal passage which supplies air from the pressure chamber to the back of the working piston under certain conditions. After the working piston rod contacts a workpiece, force of air pressure on all three pistons act on the working piston rod. An air return passage is provided to return the various components to their initial position after the working operation is complete.

Abstract: A piston assembly comprising a primary piston and a co-centric secondary piston. The pistons are received within a housing for reciprocating movement therein and relative to each other. The housing and the pistons are arranged for operating pressure to be applied to the secondary piston so as to drive both pistons within the housing. The secondary piston is provided with means enabling the operating pressure to be equalized across the secondary piston and at least one bypass passage extends through the secondary piston. The arrangement is such that upon completion of the stroke of the pistons pressure equalization occurs across the secondary piston which causes the pistons to separate. The bypass passage becomes fully operable subsequent to pressure equalization, whereby a fast return stroke is achieved.

Abstract: In a hydraulic servo unit comprising a cylinder and a piston slidably inserted therein, the cylinder chamber being divided by a piston portion into a rod-side cylinder chamber and a head-side cylinder chamber, a control apparatus for the hydraulic servo unit includes but is not limited to a first hydraulic line connecting the rod-side cylinder chamber with the hydraulic pressure source which supplies working fluid of a predetermined pressure, a second hydraulic line connecting the head-side cylinder chamber with the first hydraulic line through a first solenoid valve of duty-ratio-control, and a drain hydraulic line connecting the head-side cylinder chamber with drain through a second solenoid valve of duty-ratio-control.

Abstract: A hydraulic actuator system, for use in an aircraft, and in which the servo fluid supply to the system is used to provide for the operation and cooling of the system. The system comprises a hydraulically operated piston mechanism including at least one hydraulically operated piston, a servo vluid input to the system, which is connected in a ring main to a first side of the hydraulically operated piston, a servo fluid output from the system, which is connected in a ring main to a second side of the hydraulically operated piston, a variable restrictor arrangement which provides an interface between the servo fluid input ring main and the servo fluid output ring main, and a restrictor arrangement positioned in the servo fluid output side of the system. The position of the piston of the hydraulic piston and the adjustment thereof, are controlled by the restriction applied on the system by the variable restrictor arrangement.

Abstract: The invention concerns a cylinder-piston combination actuated by a pressure medium, comprising an outstretched cylinder space (1) and a two-part piston assembly (3, 8) movable in opposite directions in the longitudinal direction of the cylinder space (1). The piston rod (6) of the first part (3) of the piston assembly is of a tubular construction. The first part (3) is provided with a sealing between the piston (4) and the inner surface (2) of the cylinder space (1). The cylinder space (1) is provided with a connection (27) through which the pressure medium can be passed into the space (31) limited by the cylinder space (1) and the outer surface of the first part (3). The second part (8) is constructed to dimensions allowing it to fit inside the first part (3) and arranged to be movable relative to the latter. The combination includes an auxiliary piston (14) fitted around the piston rod (13) of the second part and sealed relative to the inner surface (2) of the cylinder space (1).

Abstract: A percussive tool comprising a housing (1) accommodating a movable striker (2) and connected with a power cylinder (6) in which is arranged a striker shank (4) with a gripping mechanism (14) and a drive in the form of a hydraulic cylinder (8). The percussive tool is provided with a control unit having a spool valve means (18) to control a distribution means (19). The spool valve means (18) has a casing (22) and a spool (23) taking two positions in the casing and defining two chambers (25, 26) interconnected through a throttling means (24). One chamber (25) constantly communicates with a discharge line (21), and the other chamber (26) is periodically put in communication with the space of the hydraulic cylinder (8). The spool (23) is spring-loaded with respect to the casing (22) on the side of one chamber (25) and takes in this case its first position.

Abstract: A pneumatically movable device with a safety lock means having a movable member, a pneumatic actuator connected to the movable member and adapted to move the movable member and a direction control valve connected to the actuator. A cylinder for locking is connected between one of the ports of the cylinder and the direction control valve. A spring is disposed in the cylinder for locking. Openings provided at a chamber at a side of the spring are connected to the actuator and the directional control valve respectively through a check valve disposed for preventing the air from flowing into the cylinder for locking. Openings provided at a chamber at a side remote from the spring are connected to on one hand to the actuator through a check valve disposed for preventing the air from flowing into the cylinder for locking and on the other hand to the directional valve through the check valve with a restrictor disposed for preventing the air from flowing into the direction control valve.

Abstract: Apparatus for controlling a plurality of moving members, e.g. the flaps in an installation for heating and ventilating or for air conditioning a motor vehicle, comprises single-acting actuators (46, 48) whose piston rods (50, 52) are connected to rotate the flaps about their respective axes (12, 14), with the actuators (46, 48) being fed from a pressurized fluid distributor (32) which includes moving elements which are respectively connected to control means and to each of the piston rods (50, 52), together with fluid flow servo control means for putting the displacement of one flap under the control of the displacement of another flap.

Abstract: Fluid actuation device with compensation for wear, particularly for friction clutch mechanisms of the type having a cylinder in which there are placed a first piston resting on a spring and a second piston extended by a declutching control rod, and in which the space between the pistons is filled with an incompressible fluid. The cylinder carries a separation wall between two compartments which house respectively the first and the second pistons. An orifice for communication between said compartments carried by the separation wall is associated with a stopper valve rigidly connected to a membrane that is subjected to a pressure for control and transmission of a thrust force on the cylinder and for driving the control rod.

Abstract: Pressure fluid operated percussion drilling machine comprising a frame (1) forming a cylinder space (2) for an axially movable percussion piston (3). The frame is provided with channels (4,7) connectable to a pressure fluid source (5) and to a pressure fluid container (8) respectively for pressurizing the cylinder space alternately on each side of the percussion piston in order to move it back and forth. The frame is also provided with means (12) for connection of a drilling rod (13) to the frame for directing strokes on the drilling rod by means of the percussion piston. A pressure fluid operated rotation mechanism (18) is mounted on the frame for rotating the drilling rod, which mechanism is connected to said channels for rotating the mechanism by means of a pressure fluid. The frame is provided with two outlet channels (7,19) terminating in the cylinder space at a distance from each other in the direction of movement of the percussion piston.

Abstract: A fluid motor operated by a gas or liquid and having two relatively rotatable parts comprises a plurality of pistons which cooperate with a cam member to produce the rotational output from the motor. The cam member has at least three similar lobes and forms one of the parts and the other part includes at least four cylinders each containing a piston. Each piston/cylinder combination also acts as a slide valve so as to control both the supply of fluid to one of the other pistons and the exhausting of fluid from another of the other pistons.

Abstract: This invention relates to direct acting rotary actuator cylinders wherein the linear motion of the piston is directly converted to angular motion by a means completely enclosed within the cylinder, which means comprises a slidable partitioning body engaging the circular cylindrical cavity in the cylinder in an air-tight sliding relationship and a circular cylindrical rod coaxially and rotatably disposed in said circular cylindrical cavity having a mid-section with a noncircular cross section of a diametrical dimension greater than the diameter of said circular cylindrical rod.

Abstract: A spring-loaded brake cylinder has a slideable braking piston one side of which is acted upon by a first spring in the braking direction and a second side acted upon by air under pressure in the release direction against the force of the spring. There is a releaseable mechanical coupling between the braking piston and a piston rod upon which is mounted a quick-acting piston. The quick-acting piston is actuated by air. The position of the braking piston controls a supply of air to and a discharge of air from the quick-acting piston so as to achieve pressurization and depressurization of the quick-acting piston.

Abstract: An improved rephasing master cylinder in which the cylinder wall approximate the end of the cylinder has a longitudinal bleed passage in the cylinder wall at one end connected to a lateral passage opening into the forward cylinder chamber while the opposite end of the longitudinal passage connects with the rearward chamber of the cylinder when the cylinder piston is located therebetween. This longitudinal bleed passage permits the restricted flow past the master cylinder piston when the piston is nearing and at the end of its stroke, thereby causing both master and slave pistons to complete their respective strokes.

Abstract: A manual actuator which enables manual operation of a valve, damper or other controlled element upon loss of hydraulic pressure in an associated electrohydraulic actuator assembly. The apparatus preferably includes nut segments which are automatically moved into engagement with a coacting threaded shaft upon loss of hydraulic pressure in the electrohydraulic device and which function when so engaged with the shaft to render a manual operating element effective to move the controlled part.

Abstract: A liquid motor is driven by pressurized wet glycol, received from an absorber of a natural gas dehydrating system, and utilizes the energy of the pressurized wet glycol to provide the primary source of energy for operating a pump for pumping of dry glycol from a reboiler to the absorber. A gas driven motor regulates the stroking rate of the glycol driven motor. The liquid motor and pump each have a two stage double acting piston in cylinders with fluid intake and exhaust valving and passages to alternately fill and exhaust the motor cylinders while the opposing pump cylinders are simultaneously alternately filled and exhausted. A spool type valve rod, associated with the glycol driven motor, is operated by the gas driven motor to regulate the rate of reciprocation of the glycol driven motor and to provide a secondary source of energy therefor.

Abstract: A hydraulically operated dockboard comprising a ramp which is hinged at its rear edge to the frame of the dockboard, and a lip is hinged to the forward edge of the ramp and can be pivoted between a downwardly hanging pendant position and an extended position. A main hydraulic cylinder unit interconnects the frame and the ramp, and by operating the cylinder unit the ramp can be pivoted upwardly from a horizontal cross traffic position to an upwardly inclined position. As the ramp approaches its fully raised position, hydraulic fluid is conducted from the main cylinder unit to a lip lifting cylinder which interconnects the ramp and the lip. Introducing fluid to the lip lifting cylinder will act to pivot the lip to the extended position.

Abstract: A pilot assembly for switching the fluid supply valve of a hydraulic pump is actuated by the pressurized hydraulic fluid which operates the hydraulic pump. The hydraulic pump includes a main cylinder, a main piston within the main cylinder, and a main valve for supplying pressurized hydraulic fluid to the rear end of the main cylinder for driving the piston forwardly. The pilot assembly includes a pilot cylinder and a pilot spool within the cylinder. A first hydraulic conduit connects one end of the pilot cylinder to the front end of the main cylinder, and a second hydraulic conduit connects the other end of the pilot cylinder to the main cylinder at a position spaced rearwardly from the front end of the main cylinder. When the main piston passes forwardly of the second hydraulic conduit, the pressurized hydraulic fluid in the main cylinder moves the pilot spool, and pressurized hydraulic fluid is allowed to flow to the main valve to switch the main valve.

Abstract: An improved pneumatic operating mechanism construction is provided including the usual stationary operating cylinder with a movable reciprocally-operable driving piston member movable therewithin, and having an extremely-fast pneumatic valve-device cooperable with a movable valve-sealing member attached to, and carried by, the driving side of the movable driving piston. Additionally, a valve-piston bore is provided internally within the stationary valve-housing member, within which reciprocally pneumatically operates the movable valve piston.An exhaust-port opening is provided being pneumatically communicating to the region interposed between the movable valve piston and the movable valve-sealing member, which is carried by the movable driving piston. The result is an extremely-fast valve action providing for high-pressure operating fluid, such as compressed air, for example, to be provided to the driving face of the movable driving piston.

Abstract: The instant invention relates to an electrically operated control which operates the displacement setting mechanism of a variable displacement pump and allows the displacement mechanism to be manually operated when the electrically operated control is disabled.

Abstract: As the backhoe boom 19 swings into a swing stop, hydraulic fluid is trapped in the head end 28 of the swing side cylinder 24. This trapped fluid is discharged through a cylinder relief valve, thus absorbing the boom kinetic energy and providing a smooth deceleration of the boom. Fluid discharged from the relief valve 47 is routed to the rod end of the swing cylinder and the head end of the opposite cylinder. Because of the swing linkage geometry, the cylinder rod 30 of the other cylinder had passed over the pivot axis about which the backhoe boom was swinging and thus the piston 29 of the other cylinder was caused to move in the same direction as the swing side piston 29. The movement of this piston can be utilized to provide additional deceleration torque as long as no voiding is permitted to occur in the head end of this other cylinder. Voiding only occurs when the backhoe swing control lever 38 is released prior to the backhoe boom reaching the swing stop.

Abstract: A hydraulic cylinder is provided with pistons to provide both rotary and a linear motions; utilization of a built in check valve traps fluid pressure to sustain piston in a desired operating position.

Abstract: The specification discloses a multiple dental handpiece control system in which lifting one handpiece out of its hanger blocks supply of power and coolants to all other handpieces. Each handpiece has an individual control unit and a blockout unit. When a handpiece is lifted from its hanger, it actuates a valve to cause a piston in its control unit to shift to a condition causing supply of power and coolant fluid to that handpiece and cutting off power to the corresponding pistons in the other control units thereby preventing supply of power and coolant fluids to the other handpiece.

Abstract: Total apparatus includes extensible and retractable means for moving a load linearly between two or more spaced positions, the load having a fluid pressure operated motor, and means for delivering fluid from a pressure source to the motor at selected stages of extension. A cylinder having a head end and a shaft bearing end houses a piston rod and piston which are reciprocated by fluid pressure through a pair of actuation ports. A passage extends through the length of the piston rod and through the piston to a marginal wall. Fluid pressure power ports extending through the cylinder wall are spaced longitudinally at selected stations and the piston may be moved to any station, where its passage registers with the corresponding power port. Fluid from the pressure source may then be delivered through the piston and rod and by conduit means from the outer end of the rod to the motor on the load. There are no swivel joints or hoses in the fluid path to leak or deteriorate in use.

Abstract: The lower draft link of a tractor three-point hitch includes a sensor to sense draft loads imposed on the draft link by an earth-working implement. Variations in the draft load cause variations in the pressure of the fluid in the sensor from a preselected pressure. A pilot-operated, load control valve is connected to the sensor and is shiftable in response to pressure above and below the preselected pressure to actuate a control mechanism. The control mechanism actuates a direction control valve for directing fluid to and from a hydraulic lift cylinder for respectively raising and lowering the draft link to adjust the implement so as to maintain the preselected pressure and thus maintain the desired draft load.

Abstract: A three-position pneumatic tool having a toggle trigger for actuating a control rod which in turn controls a pair of pneumatic check-valves. Three interconnected, tandemly arranged piston assemblies are operatively associated with an air pressure source at one end while also being operatively associated with a work assembly at the other end. The trigger is spring-biased to a location wherein the tool is in a neutral workpiece engaging position. Actuation of the trigger in one direction will open one of the pneumatic valves whereupon air pressure acts upon the upper surface of one of the pistons so as to lower or retract the tool to a workpiece insertion position. Release of the trigger permits the tool to attain the workpiece engaged or neutral position. Rotation of the trigger in the opposite direction permits the other pneumatic valve to open whereupon air pressure acts upon the lower surfaces of all the pistons so as to raise and actuate the tool to the operating position.

Abstract: A multiple stage hydraulic telescopic cylinder device includes two hollow pistons one movable within the other with a cylinder in which the outer piston moves. In the bottom part of the outer piston are two passages leading to the interior of the inner piston, one below and ther other above the piston area of the inner piston. Fluid under pressure is supplied to the interior of the cylinder below the outer piston, to lift it. This fluid is confined to the interior of the cylinder below the outer piston until the outer piston reaches its outmost position, whereupon a by-pass passage in the wall of the cylinder connects the interior of the cylinder to the passage in the bottom part of the outer cylinder which leads into the space of the inner cylinder below the piston portion thereof. The inner piston is then pushed out to its outer-most position.