Abstract: A tappet valve arrangement for a railway car coupler having a main valve for supplying air pressure from one railway car to another coupled railway car. A piston and cylinder valve for supplying air pressure to a coupler centering device when the railway is in an uncoupled state and for interrupting the flow of air to the coupler centering device when the railway car is in a coupled state. A negating spool valve for overriding the flow of air to the coupler centering device when the railway car is in an uncoupled state. A shut-off valve for interrupting the supply of air from one railway car to another railway car when it is desired to uncouple the railway cars.

Abstract: A pressure holding valve for pressure-fluid-actuated leveling systems in vehicles, having at least one seat valve with a valve opening, a valve seat and a valve member in which the valve member is opened by a control piston acted upon by pressure fluid. In order to achieve an absolutely pressure-tight seat valve with a long service life, an elastomer seal which seals off from the valve member is disposed on the valve seat, and pressure equalizing means are provided such that upon an impingement of pressure on the control piston in an opening direction of the seat valve, pressure build up upstream of the valve member is such that only a slight pressure difference arises at the seal at the onset of opening. In addition, the valve member is embodied such that upon displacement in a closing direction of the seat valve, the valve member substantially closes the valve opening in advance of the valve member becoming seated upon the seal.

Abstract: Hydraulic control systems are useful for controlling actuation of hydraulic motors. Some such systems use spool type valves while other systems use poppet type valves, both of which have their advantages and disadvantages. The present hydraulic control system is a hybrid system utilizing a combination of both a spool type control valve and poppet type control valves in a single work circuit. Specifically, a spool type control valve has an inlet port connected to a variable displacement pump and a pair of flow amplifying poppet type valves are serially disposed between a pair of motor ports of the spool type valve and a pair of actuating chambers of a double acting hydraulic motor. The spool type control valve is operative to control pump-to-motor flow while one of the poppet type valves is operative to control motor-to-tank flow.

Abstract: A speed control device for a pneumatic cylinder of the invention is characterized in that a speed control of the pneumatic cylinder can be changed from air pressure to air mass flow by a two-way valve and an airflow control valve. Therefore, an ordinary and low moving speed of a load is maintained even if the load changes its speed or stops moving, and thus any accidents caused by a change of the moving speed of the load are prevented beforehand. Additionally, since in this invention only a two-way valve and an airflow control valve are added to a conventional pneumatic cylinder and high relief type pressure reducing valve, the device of the invention is simply constructed and has a wide variety of usage. Furthermore, since the device of the invention is provided with a pressure accumulator and a checking valve, the pneumatic cylinder can be stably controlled even when the load moves at a high speed.

Abstract: A flow control valve has a first variable restrictor to control a flow rate of a hydraulic fluid supplied from a hydraulic fluid supply line to a hydraulic actuator and a second variable restrictor to control a flow rate of the hydraulic fluid discharged from the hydraulic actuator to a hydraulic fluid return line. A pressure compensating valve holds constant a differential pressure across the first variable restrictor, and a recovery circuit having a recovery line has a check valve that allows flow of the hydraulic fluid only toward the supply line. The recovery circuit receives at least part of the hydraulic fluid discharged from the hydraulic actuator and returns it to the supply line at a portion between the pressure compensating valve and the first variable restrictor through the recovery line upon controlling of the discharged flow rate by the second variable restrictor to thereby recover the discharged hydraulic fluid.

Abstract: Disclosed is an arrangement that includes a piston cylinder unit having pressure chamber in which fluid acts in opposition to a spring piston combination, a pressure generator and a fluid conduit extending between a tank and the tank. A first and a second valve are connected in series between the pressure generator and tank with the pressure chamber being in fluid communication with the connection between the valves. In known arrangements of the above type there is dead play wherein not every control signal corresponds to a defined position of the piston in the cylinder. However as disclosed herein the setting accuracy is improved by a throttle in parallel with valve that is fluidly connected between the pressure chamber and the piston cylinder unit. Also third and fourth valves may be connected in series between the pressure generator and tank and have a fluid connection between the third and fourth valves to the unit pressure chamber that is opposite the first chamber to provide a bridging circuit.

Abstract: A hydraulic cylinder has a piston in it with a rod projecting out of the cylinder and connectable with a tool which is operable by movement of the piston rod. A high pressure space is defined in the cylinder at one side of the piston and a low pressure space is defined at the other side of the piston. A partition defines the other end of the low pressure space. A diaphragm on the other side of the partition defines an equalizing space between the diaphragm and the partition. A low pressure line is in communication with the low pressure space and with the equalizing space. A change over valve in the lines to both the high pressure space and the low pressure space enables connection of high pressure from a pump either to one space or to the other space in the cylinder while always permitting communication from the low pressure line to the equalizing space, the connection to the equalizing space is in the low pressure line between the change over valve and a non-return valve at the pump.

Abstract: A pneumatic percussion tool includes a head valve device including first and second head valves disposed in the body and movable in response to the pressure variation in the head valve chamber. The first and second head valves are positioned at a first position for preventing communication between the main air chamber and the percussion piston chamber while permitting communication between the percussion piston chamber and the outside of the body and preventing communication between the head valve chamber and the outside of the body when the compressed air is introduced into the head valve chamber through the change-over valve.

Abstract: A hydraulic driving apparatus has at least one hydraulic pump, a plurality of hydraulic actuators driven by hydraulic fluid discharged from the hydraulic pump, a tank to which return fluid from the plurality of hydraulic actuators is discharged, and a flow control valve associated with each of the plurality of hydraulic actuators. The flow control valve has a first main variable restrictor for controlling flow rate of the hydraulic fluid supplied from the hydraulic pump to the hydraulic actuator, and a second main variable restrictor for controlling flow rate of the return fluid discharged from the hydraulic actuator to the tank. A pump control operative in response to the difference between the discharge pressure of the hydraulic pump and the maximum load pressure of the hydraulic actuators normally controls the discharge rate of the hydraulic pump so that the pump discharge pressure is raised more than the maximum load pressure by a predetermined value.

Abstract: Pressure compensating valves located downstream of the directional control valves are useful in providing load independent, proportional flow control hydraulic systems and normally serve as load checks. The subject load check and pressure compensating valve is designed for use in a hydraulic system in which the pressure of a common pressure signal directed to all the pressure compensating valves of the system is limited to a predetermined maximum level. The pressure compensating valve includes a valve element disposed downstream of a metering orifice, a separate load piston disposed in end-to-end relationship with the valve element in a common bore and a pressure compensating spring disposed in a chamber behind the load piston and biasing the load piston and valve element to the load check position.

Abstract: A valve modular control panel having a gas supply module at one end of a row of valve modules and a bleed module at the other end. Each valve module is individually controlled by its own valve mechanism. Gas under pressure is suppled to all of the valve modules from an inlet in the supply module by a passage running through all of the valve modules and terminating in the bleed module. A bleed passage runs through the valve modules and into the bleed module. All valve modules are bled through the bleed module. The bleed module is also capable of exhausting the supply passage. The panel can be expanded or contracted to include any number of valve modules which are releasably secured together by a series of nuts and tie rods. A protective shield for the panel can be adjusted in size depending on the number of modules in the panel.

Abstract: A three point implement hitch arrangement for a tractor including a frame assembly, a pair of draft arms pivotally supported on the frame assembly intermediate their ends and lift cylinders having a cylinder portion pivotally supported on the frame assembly above the draft arms and having a rod portion pivotally connected to the draft arms, forwardly of the draft arm pivotal connections. The lift cylinders are connected in series, wherein the area of the rod end of one cylinder is equal to the area of the head end of the second cylinder, whereby the cylinders may be operated independently to tilt the implement or operated in unison to lift the implement, eliminating the requirement for a complex structural support and control.

Abstract: A device for feeding energy to a cylinder rotationally mounted on a stationary machine part includes a hydraulic pump disposed in the cylinder, and a transmission device located between the stationary machine part and the hydraulic pump, the transmission device being engageable with the hydraulic pump at a drive side thereof for driving the pump.

Abstract: In hydraulic control devices comprising a two-way flow regulator in a resoir return passage, in which the flow regulator comprises a metering restriction and a pressure equalizer including a control piston with the piston ends disposed in control chambers and subjected to the action of control pressures, the actuation of a single-acting hydraulic motor under load often results in an unavoidable switching shock, because the displacement of the control piston involves the consumption of a certain volume of the pressure fluid. In order to eliminate the switching shock with a simple construction, the end of the control piston subjected to the action of the load pressure is formed as a closure element cooperating with a valve seat in the manner of a poppet valve for holding the load pressure.

Abstract: A control arrangement for hydraulic drives for driving piston pumps includes a control piston which is switchable between its end positions. The control piston has reciprocably effective longitudinally-extending flow restrictors connected into the power lines of the hydraulic drive and the control valves corresponding to each flow restrictor are provided with a pressure balancer. The direction of flow of the hydraulic fluid is the same through all flow restrictors in all switching positions of the control piston. The pressure balancer is controlled by the drop in pressure across the flow restrictor corresponding thereto. The outlet of the control valve for the hydraulic fluid flowing to the hydraulic drive and the inlet for the hydraulic fluid flowing away from the hydraulic drive are connected together at a common connecting terminal of the hydraulic drive.

Abstract: A flow regulating device is placed between a compressed air distributor and a double-acting jack for regulating the admission and exhaust flow of compressed air. The device includes a body with a cylindrical housing in which is mounted for axial sliding a movable member, and within which are two passageways transversed perpendicular to the body. Each passageway issues into a chamber defined by a bottom, the housing and the movable member. The two chambers are isolated by the movable member which comprises a central seal. The opening of the passageways are defined by stop members placed at both ends of the housing.

Abstract: Apparatus for controlling operation of an aerial lift having a boom. A hydraulic fluid pump is connected to a hydraulic cylinder, and the control arrangement controls the supply of hydraulic fluid from the hydraulic fluid pump to the cylinder and controls the supply of hydraulic fluid pressure to a first pilot fluid port and to a second pilot fluid port of a pilot operated control valve to control operation of the pilot operated control valve. A first hydrulic fluid conduit operably connects the hydraulic fluid pump to a first pilot fluid port, and a second hydraulic fluid conduit operably connects the hydraulic fluid pump to a second pilot fluid port of said control valve. A control handle selectively vents hydraulic fluid from the first fluid conduit and the second fluid conduit to control fluid pressure at the pilot ports.

Abstract: An actuator for moving a valve or other controlled part in correspondence with variations in an input signal and including a piston movable in opposite directions within a cylinder and having a smaller effective area exposed to fluid in a first chamber at one side of the piston than to fluid in a second chamber at the opposite side of the piston, a pressure fluid source delivering pressurized fluid to the first of these chambers and delivering pressurized fluid to the second chamber through a three way valve having a body containing inlet and outlet openings and a valve element movable relative thereto in a manner varying the pressure delivered to the second chamber of the cylinder.

Abstract: A fluid pressure controlling solenoid valve is disclosed for producing an oil pressure which drives a brake pressure controlling piston in a manner such that an brake oil pressure applied to the brakes associated with wheels in response to the depression of a brake pedal is adjusted to a low value in order to prevent a high slip ratio of wheels with respect to a road surface and to a high value when the slip ratio is reduced. A switching solenoid valve is assembled on the upper end face of an intermediate member formed of a magnetic material and having a first fluid path extending therethrough from its upper to its lower end face for selectively connecting the first fluid path with a reduced pressure input port and a high pressure input port. A switching solenoid valve which opens or closes the connection between the first fluid path and the output port is assembled on the lower end face of the intermediate member.

Abstract: Electro-hydraulic valve arrangements are useful in controlling a displacement control member of a variable displacement pump or motor. However, previous digital electro-hydraulic valves having brief pulse widths required special high speed solenoids to speed up the response time of the valve and resulted in increased cost of the valve. The subject digital electro-hydraulic valve arrangement includes a pair of on/off solenoid actuated valves arranged in series so that a flow path is initiated by a first of the valves and is disrupted by the second valve. The response times of the valves are equal such that directing an electrical signal to the second valve during the response time of the first valve results in extremely brief pulse widths of the valve arrangement. Using two solenoid actuated valves in this manner permits the use of less costly solenoid valves to provide very brief pulse widths through the total valve arrangement.

Abstract: An apparatus for controlling a hydraulic turbine is disclosed comprising a hydraulic circuit to control the positioning of turbine runner blades and a hydraulic circuit to control the positioning of turbine wicket gates. The runner blade hydraulic circuit comprises a solenoid valve for normal operation of the blades and a slow rate servovalve for moving the blades when the actual blade position differs from a desired position by less than a predetermined tolerance. The wicket gate circuit comprises a solenoid valve for normal control of the gates. A diverter directs flow from the solenoid valve to a flow rate control valve when the difference between the actual and desired position of the gates is less than a second predetermined tolerance.

Abstract: A hydraulic sectional control valve includes separate pump pressure and function control spools. The spools may be actuated independently and sequentially to provide raising, holding and power down functions for earthmoving and construction vehicles. Additional function control spools may be added in the valve structure to provide multiple function control.

Abstract: A pneumatic control system for machines that provides precise incremental or continuous direction, position, velocity and acceleration control of a variety of machine functions, such as rotary or linear motions, tool positioning and the like. A compressed air supply is maintained accurately at a preselected minimum pressure necessary for a particular operation, by a digitally pulsed air flow control system. Air flow and pressure to the associated actuating mechanisms is also controlled by a digital dithering technique using individual sharp pulses of air, each of which instantly breaks the static friction of the mechanism and causes a discrete precise increment of movement, with rapid consecutive pulses providing continuous motion. The direction, amount, acceleration and speed of travel are controlled by varying the pulse width and rate of air flow and pressure as necessary and for efficiency in air consumption.

Abstract: The stroke of an air driven power cylinder is controlled through a load means attached to the piston rod, a control valve means connected to the cylinder to control air exhaust from the cylinder on the extension stroke of the piston, and an external cushion valve means operably connects to the control valve means and the load means for air exhaust flow therethrough in a controlled manner but for shut-off of the air exhaust as the piston approaches the end of its stroke to trap some air in the cylinder before the piston stroke ends, the cushion valve means having a member therein of adjustable position for control of the length of stroke of the piston.

Abstract: Two fluid passages are connected through flow restrictors to a fluid supply. Downstream of the restrictors the fluid supply has a drooping pressure-load characteristic. Venting means for the fluid passages comprises vent openings therein downstream of the restrictors and variable position obstructor means cooperating with vent openings to vary venting and thereby vary fluid pressures in the fluid passages.Fluid conduits connect these pressure outputs to a double acting piston moving in a cylinder whose opposite ends are connected to the fluid conduits. The piston and cylinder form the responder of the system.A receiver is formed by a piston and cylinder or other fluidic motor remotely fluidically connected to the responder, the motor driving a load.A feedback means controlled by the position of the responder piston and/or the load varies pressure in the fluid conduits by variably venting same.Both rotary and linear types of transmitters and load feedback means and receivers may be used.

Abstract: A rotary plug steering valve of the worm gear type for auxiliary power steering of motor vehicles is provided with a rotary plug valve and a coacting valve sleeve including means for flow passage of return hydraulic fluid to a servomotor via an inner ported sleeve disposed within the valve plug, which sleeve also serves as an alignment and bearing member for the valve plug. The advantage achieved by thus providing additional serial flow control edges between the rotary plug and a return connection via the inner sleeve is the reduction of hissing flow noises in steering operations, by a throttling of return oil flow during the relative rotation of the valve plug and the inner sleeve. This reduces the cross section of return oil flow passage, but causes no throttling in neutral position of the valve for straight ahead steering when respective passages of the valve plug and inner sleeve are in full register.

Abstract: A tractor hydraulic power lift mechanism has a known manually adjustable flow control valve for regulating the rate of lowering an implement. However, when the valve is so adjusted that a heavy ground-working implement is lowered to ground level at a rate slow enough not to cause damage, the implement is then very slow to penetrate the ground to the desired working depth. A manually operable overriding mechanism preferably actuated by the main hand lever of the power lift mechanism is therefore provided to enable the valve to be moved temporarily into its fully open position and allowed to return to its adjusted position. The overriding mechanism is operated as the implement reaches ground level and released when it reaches its working depth.

Abstract: A fluid pump assembly having a body provided with a fluid chamber and a passage having an orifice, the passage connecting the chamber to a conduit carrying a pressurized flow of fluid. Pump apparatus has an inlet connected to a fluid additive supply, and an outlet which communicates with the conduit for feeding the fluid additive to the conduit. Control apparatus includes a dump passage communicating with the chamber and has a cross section larger than the orifice. A dump valve controls the flow of fluid through the dump passage to regulate the fluid pressure in the fluid chamber, and motor apparatus operatively connects the pump apparatus and the dump valve. The motor apparatus is responsive to the fluid pressure in the fluid chamber for operating the dump valve and actuating the pump apparatus to pump fluid additive through the outlet.

Abstract: A control system for operating a double-acting hydraulic ram or motor, including a proportional meter-out type directional-control valve which meters the flow of fluid out of the load and, in association therewith, a combined flow and pressure-control valve in the return line from the load. The flow and pressure-control valve is responsive to the pressure drop across the meter-out orifice of the directional-control valve such that return-line flow is restricted at high pressure drops and the supply pressure to the load is increased at low pressure drops, whereby a substantially constant pressure drop across the meter-out orifice is maintained irrespective of the size or direction of the load.

Abstract: A control arrangement for a hydraulic force transmission, especially for a hydraulically operated lifting device on agricultural vehicles comprises, besides a main control slide, a pressure control slide and a blocking device, an auxiliary slide arranged in a bore of the pre-control slide. The hydraulic working fluid is fed from the main slide directly to the blocking device and a special arrangement of the auxiliary slide in the hydraulic control circuit permits a compact and simple construction of the control arrangement, while preventing tight throttling of the fluid in either direction of the flow.

Abstract: An air motor comprising a cylinder, a piston, and a valve mechanism for controlling the supply and exhaust of air to and from opposite ends of the cylinder, the valve mechanism comprising a D-valve and an actuator for the D-valve operable by the pressure air for driving the piston, movement of the actuator being controlled by valves at opposite ends of the cylinder for exhausting air from opposite ends of the actuator, these exhaust valves being operated by the piston, and the motor having means operable by the piston at each end of its stroke for restricting the exit of air from the cylinder to cushion the piston and prevent it from striking the ends of the cylinder.

Abstract: A hydraulic system includes a fluid responsive means that controls the effective output of the pump in response to pressurization of signal fluid that is supplied by the pump. The signal fluid is pressurized by flowing through a synthetic signal generator and on into a fluid motor in opposition to the working pressure therein. This signal fluid is directed to the fluid motor by the directional control valve when the directional control valve is in an operating position; and it is directed to a sump by the directional control valve when the directional control valve is in a standby position. The present invention provides pressure actuated means to divert or occlude this signal fluid from the directional control valve except when the directional control valve provides a load sensing flow path which communicates this signal fluid to the fluid motor.

Abstract: A hydraulic control arrangement for the lifting and lowering of loads is disclosed. The system is illustrated in an industrial truck and includes a multiple element control valve with timing circuitry to eliminate unwanted transient pressure surges during valve actuation. Series-parallel oil flow paths are provided for directing and controlling oil from the load lifting cylinder to the oil reservoir when the load is being lowered.

Abstract: An hydraulic feed control system for feeding or retracting a rotary rock drill relative to the work in a selected one of four modes; namely, standard feed; regeneration feed; standard retract; and rapid retract. The system includes an hydraulic circuit controlling the feeding and retraction of feed cylinders connected to the drill; a pair of hydraulic pressure supply sources; and a pair of manipulative control valves. A primary one of the valves controls flow from one of the sources directly into the circuit; and the other control valve is selectively operable to direct flow from the other source through the primary valve into the circuit so as to combine the flow from both sources for the regeneration feed and rapid retract modes.

Abstract: A servoactuator for stopping a ram in its existing position or retracting the ram at a fixed rate to a locked position.

Abstract: A brake actuator for a vehicle having air brakes is disclosed in which air pressure is expelled through the actuator upon release of the brakes in order to purge the latter of contaminants. The actuator includes a housing in which a piston reciprocates. Fluid pressure is admitted to the chamber defined between one side of the piston and the corresponding end of the housing in order to urge the latter in a brake actuating direction. The piston includes a passage extending therethrough to connect the chambers defined between opposite sides of the piston and the corresponding ends of the housing, and a shuttle valve carried within the passage in order to close the passage upon brake application and open the passage to permit fluid communication between the chambers upon brake release. An articulated guide rod is pivotally mounted on the end wall of the housing and extends into the piston to guide the shuttle valve during operation of the actuator.

Abstract: Apparatus and method for controlling the velocity of an engine driven vehicle having a hydraulic system pump driven by the engine. Means are provided for controllably restricting the passage of fluid from the pump of the hydraulic system for controllably loading the engine and thereby controlling the velocity of the vehicle.

Abstract: A hydraulic system including a compensator connected between the service ports of the control valve and the load and arranged to restrict the flow in one or both of the service lines so as to maintain a constant pressure difference between the supply pressure and the pressure at the valve service port supplying fluid to the load. The compensator may be connected in both service lines and arranged to restrict the flow equally in each of them. Alternatively a single-sided compensator may be used, and if the load is liable to over-run it must be connected in the service line which is downstream of the load when over-running.