Abstract: The double-acting hydraulic cylinders of the lift system are connected in a master-slave series relationship. When the cylinders have been retracted to a predetermined extent, a control valve between the last slave and a primary selector valve of the system is mechanically closed responsive to the arrival of the cylinders at such retracted condition and, simultaneously, the master is prevented from further retraction by either mechanical means or another hydraulic control valve between the master and the primary selector valve. Thus, the cylinders and their interconnecting lines are cut off from inadvertent overcharging, as well as fluid escape, so that all cylinders remain uniformly extended with drift from their established positions. Several circuit arrangements are disclosed, including provision for bleeding off higher than necessary operating pressures tending to become trapped within the cylinders and their associated flow lines after the cylinders have reached the intended point of retraction.

Abstract: A control system for a push-pull unit mounted on a motor scraper has a push-pull control circuit including a bail actuating cylinder and a directional change-over valve, a suspension control circuit and an electric operating circuit for changing over the directional change-over valve to supply fluid under pressure from a hydraulic pump into either the push-pull control circuit or the suspension control circuit in accordance with the operator's indication. The directional change-over valve is changed over by an actuator connected with a pressure source through a pressurized medium passage in which solenoid operated valves controlled by the electric operating circuit are provided.

Abstract: A hydraulic system for synchronizing telescoping sections of a crane boom comprising a fixed section and second, third and fourth sections that can be extended and retracted, hydraulic cylinders between the sections for extending and retracting the adjacent sections relative to one another and a control valve for each cylinder. Cables are provided between the sections such that a non-uniformity in movement of the sections causes a change in displacement of the cables which is sensed by position sensing devices to provide a hydraulic pilot signal for modifying flow of hydraulic fluid to the cylinders.

Abstract: A piston and geared rack assembly are moved by pressurized air in opposite directions within a power cylinder housing as the vehicle operator registers door closing and opening commands in a solenoid valve. This lateral movement is converted to rotary movement by a pinion gear driven by the rack and coupled to turn a spindle shaft which drives the door. At full stroke during door closing, the power piston actuates a valve to charge the lower chamber of an auxiliary cylinder to move a lift piston rod, movable within the spindle shaft, to raise the closed door into a locked position. Upon a door-open command, the solenoid valve exhausts the charged cylinder chambers, admits air into the upper chamber of the auxiliary cylinder to move the lift piston and rod to lower and release the door, and slowly charges the associated opening chamber. This enables the delayed movement of the power piston and rack assembly in the opposite direction, reversing the rotation of the pinion and spindle shaft, to open the door.

Abstract: The invention relates to an apparatus for the exact position feedback of a double-acting power piston in a hydraulic power cylinder subjected to extreme environmental conditions, especially high temperatures, comprising a likewise double-acting detecting (measuring) or follower cylinder having a volume equivalent to that of said power cylinder and including a detecting piston the position of which can be sensed by electric means, wherein a pair of working spaces of power and detecting cylinders are in fluid communication with each other via a connecting pipe, while the respective other working spaces are adapted to be connected to a (pressurized) fluid pump or a reservoir through a control valve.

Abstract: Fluid introduced into an actuator moves the piston, against the force of a return spring, to extend the actuator. After the actuator has extended a sufficient amount to perform its intended function, the piston contacts and moves a sleeve type closure for an outlet port. The additional extension of the actuator moves the sleeve to open the outlet port. This allows fluid from the source to flow through the actuator and out through the outlet port to an expansible chamber in a second actuator. In a preferred system, the second actuator is also a single acting linear motor and it includes a return spring. At the conclusion of the function of both actuators, a bypass valve in a return line is opened to allow fluid to flow out from the expansible chambers of both actuators back to a reservoir. The fluid from the second actuator flows back to the outlet port of the first actuator and from such port through a passageway which connects such port with the inlet-outlet port of the first actuator.

Abstract: Fluid introduced into an actuator moves the piston, against the force of a return spring, to extend the actuator. After the actuator has extended a sufficient amount to perform its intended function, the piston contacts and moves a sleeve type closure for an outlet port. The additional extension of the actuator moves the sleeve to open the outlet port. This allows fluid from the source to flow through the actuator and out through the outlet port to an expansible chamber in a second actuator. In a preferred system, the second actuator is also a single acting linear motor and it includes a return spring. At the conclusion of the function of both actuators, a bypass valve in a return line is opened to allow fluid to flow out from the expansible chambers of both actuators back to a reservoir. The fluid from the second actuator flows back to the outlet port of the first actuator and from such port through a passageway which connects such port with the inlet-outlet port of the first actuator.

Abstract: A wrist mechanism in an industrial robot comprises a wrist, a rotary type actuator which is rotatable in clockwise and counter-clockwise directions, a first positioning board which can define arbitrary angular stopping positions, sensing devices, and a second positioning board which is arranged facing the first positioning board, wherein the sensing devices detect the angular position of the wrist, which is driven by the rotary type actuator, the rotary type actuator is stopped by signals produced by the sensing devices, and the second positioning board with tapered receptacles is pressed to the first positioning board with tapered pins, whereby the positioning of the wrist mechanism is carried out.

Abstract: A percussive device for creating impact impulses, which device comprises a housing accommodating a striker. The striker has a tail portion located in a power cylinder which is joined to the housing and is filled with a fluid medium under pressure, said fluid medium operating the striker. Provision is made of an arresting mechanism which is kinematically connected to a drive designed to engage the striker for effecting its backward stroke in the process of which the fluid medium under pressure is compressed, storing potential energy. According to the invention, the striker backward stroke drive is constructed in the form of several hydraulic cylinders equidistantly spaced round the periphery of the housing. The rod of each of the hydraulic cylinders is connected to the striker arresting mechanism.

Abstract: A lift truck having a particular type of upright, namely, a triple stage upright having a fixed upright section, two telescopic sections, and a load carrier mounted on the inner telescopic section. A primary lift cylinder and chain assembly is mounted from and elevatable with the inner upright section and is connected with the load carrier to elevate it with the inner section, and a secondary lift cylinder is supported from the truck and connected to elevate the telescopic sections with the primary cylinder and load carrier. A fluid conduit is provided between the primary lift cylinder and secondary lift cylinder, a first portion of the fluid conduit having a first valve interposed therein is operatively associated with the primary lift cylinder and is selectively engageable with a second valve interposed in a second portion of the fluid conduit and operatively connected with the secondary lift cylinder.

Abstract: A trim-tilt device for marine propulsion devices wherein a cylinder and a piston rod slidably fitted in the cylinder are provided to be connected respectively with a propulsion device which in turn is connected to a hull so as to be rotatable in a vertical plane, and with the hull. A tilt piston is fitted to the tip of the piston rod and a free piston is arranged on the bottom side of the cylinder as opposed to the tilt piston and a trim piston is fitted to the tip of a pipe slidably fitted to the above mentioned piston rod. The trim piston is arranged on the opposite side of the tilt piston as opposed to the free piston and is slidably fitted in the above mentioned cylinder. Oil inlet and outlet ports are provided at both ends of the cylinder Stoppers and check valves are provided for controlling the oil pressure within the piston and cylinder arrangement. The trim-tilt device permits a trimming and tilting operation with a single cylinder.

Abstract: A hydraulic pumping unit for vertically actuating a downhole pump including first and second hydraulic piston and cylinder assemblies. The first assembly is connected to the downhole pump and the second assembly is connected to a counterweight. A hydraulic line is connected between the first and second assemblies so that the counterweight counterbalances the downhole pumping equipment. A hydraulic pump is connected to the first and second assemblies through switching means for alternately supplying hydraulic fluid to and from the first and second assemblies. A check valve is provided between the hydraulic pump and the hydraulic line for replenishing the assemblies with fluid. A safety valve is connected between the first assembly and the hydraulic line for preventing the first assembly dropping in the event of a hydraulic line failure. A return valve in parallel with an orifice closes in the event the hydraulic pump stops for preventing free fall of the first assembly.

Abstract: A valve actuation system is provided for a valve of the type wherein at least two separate movements are utilized to achieve either opening or closing thereof. The actuation system includes a pair of hydraulic or pneumatic actuator units for automatically performing these two separate operations. An electrically energizable control valve is associated with each of these actuators for controlling the flow of a pressurized control medium therethrough to achieve actuation in the proper sequence for attaining the desired valve movement. A control circuit preferably comprises a plurality of switches responsive to the positions of these two valve actuators as well as the position, (viz., "valve open" or "valve close") of an operator accessible main control lever or switch. These switches deliver electrical power to energize the fluid flow control valves so as to automatically perform the correct sequence of actuator operations to open or close the valve, as desired.

Abstract: Two circuit breakers or circuit breaker modules are actuated by hydraulic jacks fed by supply and drain valves operated by a single closing-operation control unit. A differential pressure detector is subjected to the pressure of the two jacks. In the event of a relative variation in the jack-operating times, the free piston of the detector actuates a switching device which connects the supply and drain valves to the drain tank, thus preventing the complete performance of any non-simultaneous operation of the circuit breakers.

Abstract: A hydraulically operated conveying mechanism for a manure spreader composed of a fore-and-aft shiftable floor extension that is supported on a fixed floor of the spreader box and a transverse vertical push-off supported to shift fore-and-aft on the extension. First and second hydraulic cylinders are used to shift the floor extension and push-off respectively and includes a first cylinder and associated rod with the latter being composed of inner and outer concentric tubes closed at their respective ends and with the inner tube opening into the closed end of the cylinder. The outer tube has a port opening into the cylinder. The second double-acting cylinder that operates the push-off has its opposite ends in fluid communication with the inner tube and outer tubes. A shuttle valve within the main cylinder shifts axially to close the port as fluid is introduced to the closed end of the main cylinder and opens the port as the rod approaches its fully extended position.

Abstract: A manure spreader having an upwardly opening box-like structure with a beater mechanism at its open rear end through which material may be reduced and thrown from that end. The conveying mechanism provided in the box-like structure for moving materials to the rear beater mechanism is composed of a fore-and-aft shiftable floor extension that is supported on a fixed floor of the box-like structure. The floor extension carries a transverse vertical push-off wall supported to shift fore-and-aft on the extension. In a fully extended position, the floor extension is at the front end of the spreader box and the push-off wall is on the front end of the extension. Manure or material in the box is pushed into the beater mechanism through hydraulic power which first shifts the floor extension rearwardly and in overlying rear position with respect to the fixed floor so that the rear edge of the floor extension is closely adjacent the beater mechanism.

Abstract: An adjusting drive operated by a pressure medium with a spring-loaded roller diaphragm secured to plates and displaceable within a housing by the pressure medium; the roller diaphragm actuates an adjusting member that is securely connected with a plate and extends out of the housing; in addition to its end positions, the adjusting member is also able to assume at least one intermediate position; the plates are thereby connected with each other by the roller diaphragm while a plate not directly connected with the adjusting member sealingly rests on a ring-shaped abutment projecting out of the inner wall of the housing in the intermediate position of the adjusting member.

Abstract: A vehicle brake booster and master cylinder assembly has a vacuum suspended booster section which is controlled by movement of the vehicle brake pedal. A hydraulic booster section is in series with the vacuum suspended booster section, and a master cylinder unit is in series with the hydraulic booster section. The assembly is so arranged that in normal operation the vehicle operator obtains boosted brake actuating pressures by operation of the vacuum suspended booster which acts through the hydraulic booster mechanism without operating the hydraulic booster. When greater brake actuating pressures are required, as indicated by increased brake pedal force exerted by the operator, the vacuum booster reaches its limit or runout condition and the hydraulic booster is operated so as to continue the increase in master cylinder output pressure.

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: A power piston apparatus, comprising two or more double acting hydraulic piston drive means in which the cross-sectional areas of the pistons are identical and the cylinder spaces or chambers of which are hydraulically interconnected in crossed fashion above and below the pistons in the case of two cylinders, while being connected in series in the case of more than two cylinders having separately closed oil spaces of identical volumes, with each such oil space being connected to a positive-pressure oil supply through check valves for replenishing the leakage oil, and wherein said piston drive means have associated therewith metering cylinders with a coaxial and/or parallel direction of stroke, i.e. with mechanical connections between the ends of the piston rods.

Abstract: A three-stage, four-section telescopic ram employing a plurality of internal fluid passages, with valving provided in certain of these passages, to produce a uniform overall extension speed when pressure fluid is supplied to the ram at a substantially constant rate.

Abstract: A hydraulic positioning drive with a physically separated work cylinder which is connected via pressure oil lines, comprises a follow-up cylinder mounted at the positioning drive or in the immediate vicinity thereof, of the same type and the same volume as the work cylinder, which is hydraulically connected in series with the latter, so that its piston moves synchronously with that of the work cylinder. The piston position of the follow-up cylinder is sensed electrically and used as the positioner position. For synchronizing, both cylinders are connected in parallel from time to time and their pistons are run into the end positions.

Abstract: This invention is directed to fluid actuated apparatus for automatically restricting the flow of fluid in conduits leading to and/or from fluid actuated cylinder means for causing pivotal movement of a member, such as the turret carrying the boom and bucket of a backhoe, so that the speed of pivotal movement of the member is rapid during one portion of its pivotal movement but is automatically reduced during a predetermined portion of its subsequent pivotal movement, thereby minimizing failures of the components of the member and the fluid system and improving the braking action for reducing the speed of pivotal movement of the member. In one embodiment, both the flow of fluid to the operative fluid actuated cylinder and the flow of fluid from the inoperative fluid actuated cylinder are restricted substantially simultaneously by fluid restricting means so that the linear velocities of the rods of both cylinders are reduced substantially simultaneously by the fluid restricting means.

Abstract: Automated control apparatus for an intermittently extended hydraulic cylinder is disclosed which governs cylinder elongation such that the rate of elongation is essentially constant with respect to time. The control apparatus includes a preset continuously variable timer that regulates the timer interval between sequential length increments of the cylinder. The control apparatus also includes a second timer which is responsive to the timer interval interposed by the first timer and which operates a valve controlling communication of hydraulic fluid between a hydraulic cylinder and a pump. The second timer may be discretely variable so that one of a plurality of predetermined length increments can be selected. Alternatively, the second timer may adjust the time period during which the valve is opened such that successive stages of a telescopic hydraulic cylinder have equal length increments.

Abstract: A vacuum motor suitable for actuating a carburetor choke valve has primary and secondary stages responsive to separate vacuum signals. The secondary stage is carried by the primary stage and has a valve which opens upon full retraction of the primary stage to permit application of a vacuum signal to the secondary stage.

Abstract: Apparatus for automatically sensing when an insufficient amount of fluid exists in a closed fluid power transmission system of a telescoping piston type hydraulic elevator system and circuitry shown interconnected with the control system of a typical hydraulic control system for automatically initiating a fluid restoration cycle to restore fluid to that closed fluid power transmission system to enable the system to operate in a desired manner.

Abstract: A multistage, extensible-contractible hydraulic ram assembly for use in conjunction with a triple-lift-type mast in a lift truck. The assembly is designed for mounting in such a truck in a so-called inverted position. It is constructed with special, externally actuated, internal valving which, through controlling the action of pressure fluid within the assembly, assures positive control over the sequence of movements of the sections in a mast as such are raised and lowered, without requiring latching and interlocking of these sections. Further, the assembly features the capability of producing substantially uniform or constant lifting and lowering speeds for a load which is carried on the usual carriage mounted on a mast of the type indicated.

Abstract: A single-acting, three-stage, four-section telescopic ram for use in conjunction with a triple-lift type mast in a lift truck. The ram features an extremely low overall length when fully contracted, thus affording good operator visibility. The ram also is capable of producing surprisingly "high-lift" despite its low contracted profile. Further, the ram features an internal construction that produces constant lifting and lowering speeds for a load, as well as providing for positive control over the sequence of movements of parts in and on an associated mast.

Abstract: The invention is especially suitable when front and rear wheels are hydraulically steered, each set by its own hydraulic cylinder, the two cylinders being connected in hydraulic tandem so that the same angularity of steering will be imparted to both sets of wheels. The self-synchronizing of the present invention overcomes a serious prior fault that occasionally a nonsynchronous relationship would develop. The present invention opens a synchronizing valve on the occasion of each extreme swing of the wheels. A check valve then ensures a synchronized return swing.

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: Apparatus for transporting work over a predetermined path previously requiring a transporting mechanism of a minimal dimension with respect to the corresponding dimension of the path. A transport mechanism is provided for transporting the work over a portion of the path, which transport mechanism has a corresponding dimension substantially less than the minimal dimension. The work is initially maintained in a position in which it is propelled by the transporting mechanism. A further transporting mechanism is provided, which mechanism also has a corresponding dimension substantially less than the minimal dimension. A transfer mechanism transfers the work from a position in which it is propelled by the transport mechanism into a position in which it is propelled by the further transport mechanism.

Abstract: A rigid, multiple-passage, quick-disconnect coupling in which valves of a supply section of the assembly are moved to mechanically open valves in a receiver section for enabling pressurization of telescopic cylinder sections. Energization of the innermost cylinder section automatically actuates the valves for enabling pressurization of the remaining cylinder sections. The coupling sections have opposed valve surfaces substantially flush with the surrounding surfaces of the coupling sections.

Abstract: A hydraulic control system having a plurality of hydraulic motors is provided with a sequencing control means for sequentially controlling or operating the motors from a single selector valve. The selector valve is operative to direct pilot fluid through a sequential controlling valve for pilot operation of separate pilot-operated control valves for the separate motors. The sequential control valve is operative to direct the fluid for operation of one of the control valves first for full operation of the first motor and then for directing pilot fluid to the second valve for operating the second motor. For operating the motors in the reverse direction, the second control valve is operative to control the second motor to its fully retracted position and then the first control valve becomes operative until the first motor is fully retracted.

Abstract: The actuator comprises a cylinder of non-circular cross section, two types of pistons and a piston rod which is provided with at least one spiral male thread having a pre-determined helical angle at a pre-determined pitch. One of the piston is mounted on the piston rod for rotation relative thereto while being fixed against axial displacement therealong, and is provided with two relief pressure control valves opening in respective opposite directions, and the other piston is provided with at least one female spiral thread engaged with the male thread on the piston rod. The rod can thus reciprocate in the cylinder in opposite axial directions and can rotate, relative to the cylinder, in opposite angular directions.

Abstract: This invention relates to a telescopic jack constituted by a main cylinder, a first piston sliding in said main cylinder, a first piston rod fast with the first piston which passes in tight manner through a first bottom of the cylinder, a second piston which may be disposed in a bore of the first rod and is mounted to slide with respect to the first piston, and by a second piston rod which is fast with the second piston.The second piston rod passes through the second bottom of the cylinder whilst the piston is separable from the rod.One application of the invention is the production of an inexpensive telescopic jack.

Abstract: A hydraulic actuator for producing translational movement over a long distance having two jack cylinders with pistons mounted for reciprocal movement and connected to a worm wheel through a worm gear. When a piston is driving, the worm gear acts as a rack to turn the worm wheel and when a piston is being returned to its starting position the worm gear rotates. Means are provided to alternately switch from one cylinder to the other.