Abstract: A valve, in particular for use as a pressure compensator or maintenance-type component (38) in hydraulically actuated hoisting devices (2), has a valve housing (54) with a control port (40), a fluid inlet (64) and a fluid outlet (66). A regulating piston (68) is longitudinally displaceably in the valve housing (54) and acts against an energy storage device (70) in the form of a compression spring, bringing the regulating piston (68) into positions forming a fluid-conveying connection between the fluid inlet (40) and the fluid outlet (66) or blocking this connection by a control pressure existing at the control port (40). A first orifice (88) in the regulating piston (68) connects the control port (40) to a receiving space (62) for the energy storage device (70) in a fluid-conveying manner. A second orifice (90) is in an intermediate part (72) in the valve housing (54).

Abstract: A system uses a two-stage electrohydraulic servo valve that includes an additional control port that commands a fail-fixed valve to lock the position of a device in the last commanded position. The additional port is modulated by an existing land on the EHSV valve element, adding little to no complexity. Major technical benefits of the disclosed system are that it adds little to no cost, complexity, size, or weight the device being controlled. The disclosed configuration allows for the use of a relatively small and simple fail-fixed valve, and the control ports on the controlled device keep “drift” to a minimum, when transitioning between normal operating mode and fail-fixed operating mode.

Abstract: An electrohydraulic system for use under water includes an electrohydraulic actuator and a container having an internal space provided for forming a volume which is enclosed from the environment and which is provided for receiving a hydraulic pressurized fluid. A hydraulic cylinder is provided in the internal space of the container, the inside of which is divided into a first cylinder chamber and a second cylinder chamber by a piston to which a first piston rod and a second piston rod are connected. The two active surfaces of the piston are the same or approximately the same size.

Abstract: A sub-system 200 for an aircraft hydraulic system 20 that includes a first inlet 202 for receiving fluid from a supply 22 of hydraulic fluid, a system valve 210 for controlling fluid flow from the sub-system 200 to a hydraulically-operable system 24 of the aircraft hydraulic system 20, a check valve 220 for permitting fluid flow from the sub-system 200 and preventing or hindering fluid flow into the sub-system 200, a second inlet 240 for receiving fluid from a second supply 28 of hydraulic fluid, and a selector 230. The selector 230 configured to place the system valve 210 in fluid communication with the first inlet 202 when the selector 230 is in a first state, and to place the system valve 210 in fluid communication with the check valve 220 and the second inlet 240 when the selector 230 is in a second state different from the first state.

Abstract: A servo actuator is provided which may comprise a controller configured to control a plurality of solenoid valves based upon an output signal. The plurality of solenoid valves may be used to control the position of the object. For example, a set of solenoid valves, of the plurality of solenoid valves, may be configured to conduct fluid from a tank into a first chamber of the cylinder, conduct fluid from the tank into a second chamber of the cylinder, conduct fluid from the second chamber of the cylinder into a first solenoid valve and/or conduct fluid from the first chamber of the cylinder into the first solenoid valve. The first solenoid valve, of the plurality of solenoid valves, may be configured to conduct fluid from the set of solenoid valves into a vent valve based upon a pulse width modulation (PWM) signal received from the controller.

Abstract: Systems and methods for mast stabilization on a material handling vehicle are provided. In one aspect, the present disclosure provides systems and methods for a hydraulic circuit configured to stabilize a mast of a material handling vehicle in dynamic and static events. The hydraulic circuit is integrated into a typical hydraulic system used to raise and lower the mast and thereby a load supported by the mast.

Abstract: Hydraulic actuation systems having concentric chambers, variable displacements and energy recovery capabilities include cylinders with pistons disposed inside of barrels. When operating in energy consuming modes, high speed valves pressurize extension chambers or retraction chambers to provide enough force to meet or counteract an opposite load force. When operating in energy recovery modes, high speed valves return a working fluid from extension chambers or retraction chambers, which are pressurized by a load, to an accumulator for later use.

Abstract: The present invention relates to a trim actuator actuating system having two separate hydraulic power supply systems, through which it is possible for the first time to use a hydraulic linear actuator as a trimmable horizontal stabilizer actuator in an aircraft. The at least one hydraulic linear actuator is coupled to the first power supply system in such a way that it applies hydraulic power to the linear actuator during normal operation. In order to ensure the application of pressure to the hydraulic linear actuator in case of breakdown, in such a case, the pressure application to the hydraulic linear actuator is maintained with the aid of the second hydraulic power supply system.

Abstract: A fluid power valve module has a supply port for fluid and at least one fluid power and more especially pneumatic valve able to be controlled via the control interface of the valve module for control of a fluid power instrumentality by way of power ports on the basis of the supplied fluid. There is a provision such that the valve module comprises at least one switching output integrated in its housing for output of a switching signal for switching a switching means for influencing and more especially deactivating the instrumentality.

Abstract: A hydrostatically driven vehicle has an engine operating a variable displacement propel pump, a displacement of which can vary based on an angle of a rotating swashplate, such that a fluid flow impelled by the pump transfers power to at least one propel motor rotating a wheel of the vehicle. An electronic controller of the vehicle senses an operating parameter of the system, for example, the angle of the rotating swashplate or the direction and speed of rotation of the propel motor with a sensor to yield an actual signal, and relays the actual signal to an electronic controller. The controller determines a desired angle for the rotating swashplate based on the control signal, and compares it to the actual signal from the sensor. Motion of the vehicle is stalled when the angle signal differs from the desired angle by a predetermined extent and for a predetermined period.

Abstract: An actuator displacement servo-control for aircraft flight controls is assisted by a hydraulic circuit, configured to deliver a hydraulic failure indication. The servo-control is generated from an actuator position indication and a position set-point indication computed by a computation unit. An alarm phase is opened on detection of a servo-control operating error and is kept open as long as the error is present. During the alarm phase it is determined whether the actuator is in blocked or divergent states. If blocked, it is determined whether the duration of the alarm phase exceeds a value Tconf2; If divergent, it is determined whether the duration of the alarm phase exceeds a value Tconf1. When blocked and the duration of the alarm phase does not exceed Tconf2, it is determined whether the hydraulic circuit indicates a hydraulic failure.

Abstract: A solar panel carrier T is provided at a sub-structure U such that it can be rotated and tilted by means of hydrostatic rotation and tilt motors M, M?. In an electrohydraulic adjusting device for the solar panel carrier T a motor pump aggregate 8 is connected to the hydrostatic motors. Within working lines A, B of the tilt hydrostatic motor M at least one tilt control system K is provided, which comprises valve components and a pilot pressure circuit. The tilt control system K comprises pressure actuated blocking valves or load holding valves LHVA, LHVB. For automatically adjusting a protected position S of the carrier T a suction line N is provided at the side of the hydrostatic tilt motor facing to the blocking valves or load holding valves. The suction line N is surveyed by a monitoring solenoid 18 and is opened depending on initial pressure conditions in case of switching off the electric power and/or in case of an electric breakdown.

Abstract: A hydrostatic pump (1) with a variable delivery volume can be operated in a closed circuit. An electrically controllable actuator device (4) is provided for the control of the delivery volume of the pump (1). The electrically controllable actuator (4) has an electrically actuatable control valve device (6) which generates a positioning pressure which actuates a positioning piston device (5) which is in an operative connection with a delivery volume control device (3) of the pump. An electrical position feedback circuit (21) of the delivery volume control device (3) is provided and the actuator device (4) is provided with a switchable hydraulic neutral position control system (25), by means of which a restoring movement can be generated that acts on the positioning piston device (5) and places the delivery volume control device (3) into a neutral position.

Abstract: A hydraulic circuit is provided, which can prevent the bucket from being separated from the bucket rest by preventing a change of stroke of a boom cylinder or an arm cylinder during long traveling of wheel type heavy equipment, and can secure safety since it is not required for an operator to adjust the position of a working device like boom and arm. The hydraulic circuit includes first and second hydraulic pumps, a boom cylinder, an arm cylinder, a boom confluence logic valve, a first port formed to connect with a large chamber of the boom cylinder in a housing in which a spool for the boom cylinder is shiftably installed, a second port formed to connect with a hydraulic tank in the housing, and a first orifice formed between the housing and a land part of the spool for the boom cylinder located between the first port and the second port.

Abstract: A system for reducing oscillating movement of a boom assembly about a fore-and-aft aligned axis defined by a pivotal connection of a suspension arrangement independent of a carrier frame is provided. The system includes an accumulator, a cylinder actuator mechanically interconnected between the carrier frame and the boom assembly, and a metered orifice connected in fluid communication to restrict a fluid flow between the accumulator and the cylinder actuator. In response to rotation of the boom assembly in a first direction relative to the carrier frame, the system creates a force resisting the rotation of the boom assembly in the first direction. Thereby, the system deadens oscillating pivotal movement of the boom assembly relative to the carrier frame and exerts a biasing force to assist in returning and/or maintaining the boom assembly at a generally horizontal alignment.

Abstract: A system to lock a roll-suspension arrangement operatively connected to allow pivotal movement of a boom assembly about a fore-and-aft axis independent of a carrier frame is provided. The system includes an actuator cylinder having an end movable in a linear direction relative to a fixed end. The fixed end of the actuator cylinder is connected at the carrier frame, and the movable end is connected at the boom assembly. The system further includes a lock valve located in fluid communication with the actuator cylinder. The lock valve in a closed position prevents a fluid flow therethrough so as to restrain movement of the actuator cylinder and rotation of the boom assembly with respect to the carrier frame. In an open position, the lock valve releases movement of the actuator cylinder so that the boom assembly freely pivots independently of the carrier frame.

Abstract: A failure detection device for a hydraulic motor of the present invention comprises a hydraulic pump 3 that is driven by a prime mover 2; a hydraulic motor 1 that is driven by hydraulic oil discharged from the hydraulic pump 3; an abnormality detection device 35 that detects an abnormal operation of the hydraulic motor 1; and a warning device 30, 39, 40 that issues a warning when the abnormal operation of the hydraulic motor 1 is detected by the abnormality detection device 35.

Abstract: An electro-hydrostatic actuator unit that contains a sealed pressurized housing filled with a dielectric fluid. A bi-directional motor is immersed in the fluid and drives a gear pump for exchanging fluid via a control circuit between the chambers of a bi-directional hydraulic actuator in response to an input from a controller. The chambers are separated by a piston and a piston rod is connected to an external load such as a plunger type valve. A failsafe circuit is also provided which is arranged to override the control circuit in the event a failsafe condition is detected by the unit controller. The failsafe circuit contains a motor driven pump that provides high pressure fluid from the pressurized reservoir to an accumulator. Valves are arranged to shut down the control circuit and deliver fluid from the accumulator to one of the cylinder chambers to rapidly move the actuator to a desired failsafe position.

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

Abstract: A fluid control system for security relevant control and a fluid control actuator, a local control means for a fluid control system, a software module for a local control means of a fluid control system and a method for the operation of a fluid control system. The fluid control actuator (10) is controlled by control instrumentality means (30) of a local control means (50). A sensor (16, 17, 27, 41 and 42) transfers information concerning operational states of the fluid control system to the local control means (50). For this purpose there is a provision such that the local control means (50) determines from such information whether there is a security relevant situation and if necessary performs a predetermined function. The security relevant functions are integrated in the fluid control system so that same is able to be employed as prefabricated unit.

Abstract: A double-acting, piston driven actuator for providing a double action rotary powered output, having a stepped bore housing a double acting piston having a larger diameter end and a smaller diameter end therein; a three way valve selectively to supply pressurized fluid to the larger end the pressurized fluid continuously supplying the pressurized fluid to the smaller diameter portion of the bore. An optional safety mechanism having a spring biased second piston for biasing the double acting piston to a safe position upon failure of the pressurized fluid delivery system is also provided.

Abstract: A device for preventing the unintentional restarting of motors or machines is proposed, it being possible to control the supply of energy to the motor or to the machine by means of a control valve with a mechanically adjustable control element and it being possible to connect the control valve non-detachably to the motor or to the machine, the energy for the motor being generated by means of compressed air, and in that a pneumatic piston, to which the primary air pressure prevailing upstream of the motor and upstream of the control valve can be applied, being arranged as a restarting inhibitor between the control valve and the motor, and in that, in order to apply the primary air pressure, a connecting line being arranged between the motor and the piston.

Abstract: A double-acting, piston driven actuator for providing a double action rotary powered output, having a stepped bore housing a double acting piston having a larger diameter end and a smaller diameter end therein; a three way valve selectively to supply pressurized fluid to the larger end the pressurized fluid continuously supplying the pressurized fluid to the smaller diameter portion of the bore. An optional safety mechanism having a spring biased second piston for biasing the double acting piston to a safe position upon failure of the pressurized fluid delivery system is also provided.

Abstract: A redundant control actuation system (100) provides hydraulic logic cross-coupling between physically-separate servoactuators (101A, 101B). Each servoactuator has a control valve (102A, 102B) arranged to provide a hydraulic output in response to a control signal. Each actuator also has a hydraulic actuator (106A, 106B) arranged to move a load in response to the hydraulic output from its associated control valve. Logic valve means (103A, 104A, 105A, 103B, 104B, 105B) are operatively associated with the control valves (102A, 102B) and actuators (106A, 106B). Each logic valve means is supplied with hydraulic and electrical input signals.

Abstract: A structure comprising firstly a differential sensor of linear displacement comprising a body and a core slidably mounted relative to said body, and secondly a rod of a servo-control actuator in which the core is mounted, said rod terminating in an endpiece which has a bore in which the core is received close to its end, said bore and the core having complementary threads which co-operate to hold said core relative to said bore, and means enabling the engagement of the core in said bore to be adjusted, wherein said means comprise an adjustment screw extending through the actuator rod and whose thread co-operates with complementary means carried by the core so that turning movement applied to the adjustment screw by an operator gives rise to axial displacement of the core in the bore of the endpiece.

Abstract: Active control system for a movable member, in particular a tailgate or door, includes a pump unit which is connected by at least one fluid connecting line to a piston-cylinder unit. The control system has an on-off valve through which the direction of motion of the piston-cylinder unit is controlled. A pressure-limiting valve is operable, in emergency conditions, to permit a displacement motion of the piston rod of the piston-cylinder unit by opening a connection to the working chamber of the piston-cylinder unit.

Abstract: A hydrostatic steering device having substantially identical first and second steering systems, each including a pump connected to a steering unit, which is connected to a steering motor by two motor hoses. A steering wheel is common to both steering units. The device includes a change-over valve which has an operation position hydraulically coupling together the two motor hoses of the second steering system, while hydraulically isolating from each other the two motor hoses of the first steering system, and an emergency position hydraulically coupling together the two motor hoses of the first steering system, while hydraulically isolating from each other the two motor hoses of the second steering system. A switching device switches the change-over valve from the operation position to the emergency position, when a fault occurs in the first steering system.

Abstract: A hydraulic system for retracting into and extending out of the body of an aircraft a landing gear for use in taking off and landing, comprises a housing unit which has a hydraulic pump, a hydraulic actuator, a shuttle valve, an emergency valve, an actuator pressure releasing mechanism, and a mechanically locking mechanism accommodated therein. The hydraulic actuator has a piston rod assembly received therein to be reciprocably moved by the hydraulic pump to assume a retraction position and an extended position. The shuttle valve is movable with respect to the housing unit for selectively changing the flow of the hydraulic fluid between the hydraulic pump and the hydraulic actuator. The emergency valve is movable with respect to the housing unit to assume two different positions for selectively changing the flow of the hydraulic fluid between the hydraulic pump and the hydraulic actuator and the flow of the hydraulic pump and the fluid pressure reservoir.

Abstract: A power steering cylinder assembly including a cylinder divided by a piston into opposite chambers and a valve controlling flow between a pump, a tank and the chambers. Bypass passages selectively connects the opposite chambers when there is no flow from the pump. The bypass passages includes first and second sets of axial passageways in the wall of the cylinder. Each passageway of the first set of axial passageways having an inlet in the first operating chamber and a first outlet in the exterior of the cylinder. Each passageway of the second set of axial passageways having an inlet in the second operating chamber and a second outlet in the exterior surface of the cylinder. The first and second outlets being in two respective circumferential lines on the exterior surface of the cylinder.

Abstract: A self-centering motor (16) includes a piston (130) which is disposed in a housing (112) and is movable in opposite directions from a centered condition. A pair of centering members (160 and 162) are disposed in the housing (112) to effect movement between the piston (130) and the housing toward the centered condition upon the occurrence of a predetermined condition, such as failure of a pump (44) to supply fluid under pressure. The members (160 and 162) which effect movement of the piston (130) to the centered condition are normally disposed in an overlapping relationship which enables the motor (16) to have a compact construction. In one embodiment of the invention, the members (160 and 162) which effect movement between the piston (130) and the housing (112) toward the centered condition include an inner centering member (162) and a cylindrical outer centering member (160) which extends around the inner centering member.

Abstract: An electro-hydraulic valve actuator comprising an actuator casing; a piston/rack means in the casing having walls reciprocating linearly to effect linear movements, the reciprocating walls defining a center chamber therebetween and two outside chambers inside the casing; an output shaft in communication with the piston/rack means for driving a valve, the output shaft effecting rotational movements in response to the linear movements of the piston/rack means; resilient return means in each of the two outside chambers engaging the reciprocating walls of the piston/rack means and inner end walls of the casing, the resilient return means biasing the reciprocating walls of the piston/rack means to a closed position; a pumping means; a primary internal flow path for transferring hydraulic fluid from the pumping means to a first output port and into the center chamber, the hydraulic fluid in the center chamber causing the piston/rack means to expand in the casing to transmit the linear movements to the output shaft;

Abstract: A fluid driven reciprocating engine includes a main body having an inlet for receiving a primary fluid and an outlet for discharging the fluid. A drive piston is sealingly mounted in the main body for reciprocating movement in response to flow of the primary fluid through the body. The drive piston divides the body into first and second chambers. A first valve selectively transmits the primary fluid from the inlet to the first and second chambers and a second valve selectively transmits the primary fluid from the first and second chambers to the outlet. An overcenter linkage mechanism that operably interconnects the drive piston and the first and second valves.

Abstract: The present invention provides a servo-actuator capable of operating in both the Fail Safe and Fail Operate modes. In the Fail Safe mode, a pretensioned spring member moves a jet pipe in the servo-valve to cause said actuator rod to move in a first direction upon loss of electric power. A mechanical feedback means coupled to said spring member and said actuator rod opposes the force applied by the spring so that when a force equilibrium is reached the actuator rod will be at a predetermined position.

Abstract: The present invention provides an actuator controlled by an electro-hydraulic servovalve with a failfixed operation upon the loss of electrical power to the servovalve. A lock valve has apertures therethrough with friction pads therein for locking the actuator in position upon loss of the electrical power.

Abstract: A fluidic stiffness enhancing circuit for use with a fluid driven piston type actuator includes a fluid conduit arrangement that interconnects two variable volume chambers of the actuator upon occurrence of a loss of system pressure to at least one of the chambers. The fluid conduit arrangement incorporates an inertance device for controlling the rate of flow of fluid therethrough so as to control the pressures in the two chambers in response to external forces applied to the actuator piston and thereby the stiffness of the actuator.

Abstract: A machine tool is suggested, which has a headstock (111) and at least one tool changer (120). The tool changer (120) moves production tools (116) between a magazine position and a working position, at least one fluid power drive cylinder (1) being associated with it as a drive unit (123). On the drive cylinder (1) a locking device (52) is provided, which when a working pressure of the drive piston (6) drops below a predetermined value produces a mechanical locking action of the drive cylinder piston in relation to the housing. To release the mechanical locking, a setting force due to the working pressure must be overcome.

Abstract: A safety circuit for a servo-hydraulic regulating system for the hydraulic control and actuation of load units, such as operating tools on utility vehicles and agricultural machines. The controlling of the load unit is effected via a proportional valve which is actuated in dependence upon a pair of output signals of a measuring bridge in such a way that, in the event of a balanced measuring bridge, it assumes a neutral setting in which the operating line running to the load unit or emanating from the load unit is blocked. In order to prevent the lifting gear from executing a regulating reaction if the measuring bridge is out of tune when the servo-hydraulic regulating system is switched on, a safety valve arrangement is provided in the operating line.

Abstract: A detector switch of the present invention is capable of confirming that an electrical signal from a controller to an electromagnetic valve has been transformed into the operation of a control valve spool when the speed of a transmission of automobiles or construction machines is changed. To achieve this, in a transmission having control valves having a spool (3) for changing the hydraulic pressure of a transmission clutch, a controller (5) for turning ON and OFF electromagnetic valves (2.sub.1, 2.sub.2, 2.sub.3,) the control valves (1.sub.1, 1.sub.2, 1.sub.3) are provided with a detector switch (7) which is capable of transmitting a signal to the controller (5) when the spool (3) abuts against the switch (7).

Abstract: This actuating drive (1) for a control valve (2) has a control circuit which sets the actuating drive (1) to correspond with a specified required value from an overriding installation control system. It has, in addition, a main piston (6) sliding in a main cylinder (5) with a drive volume (7), on one side of the main piston (6), which can be acted on in a controlled manner by oil under pressure and has a plate valve (17) fitted upstream of the drive volume (7).The intention is to create an actuating drive, for a control valve, whose dynamic behavior can be improved by relatively simple means. This is achieved by the plate valve (17) being provided with a separate reservoir volume, connected to a drain appliance, for the oil emerging from the plate valve (17).

Abstract: The invention relates to a system for powering the driving actuator of an aircraft undercarriage, the system including a hydraulic generator capable of delivering fluid under pressure to one or the other of two chambers of the driving actuator. According to the invention, the power supply system includes a safety device enabling any overloading of the actuator rod under the effect of pressure peaks to be avoided: said device comprises two pressure relief valves, the first valve limiting the pressure delivered to the annular chamber and being under the control of the pressure in the full-section chamber, and the second pressure relief valve being of the differential type and continuously controlling the pressure difference between the two chambers of the actuator. The invention is applicable to providing very safe power supply systems for aircraft undercarriages.

Abstract: This hydraulic safety and regulating system for a steam feed of a turbine has a rapid-action (4) and a steam regulating valve (3), and a line system monitored by a safety downward-control unit (22). The monitored line system is designed as both a power oil supply and as a safety oil system. This results in a hydraulic safety regulating system which is simple to build and has a reduced number of possible leakage points.

Abstract: A blow-back circuit (10) comprising an accumulator (23) to build up system pressure during normal system operation and an accumulator shut-off valve (13) which prevents dissipation of the accumulator pressure during normal operation. Pressurized fluid is supplied to a fluid motor (11) through a direct drive valve (12). A directional control valve (28) is associated with a switching valve (34) and a stop mechanism (31) which mechanically feedbacks the position of a control surface to be blown back during an emergency. When the control surface is in or blown back to the neutral position, the stop mechanism (31) feeds that data back to the directional control valve (28) so that accumulator pressure will not be further delivered to the fluid motor (11) and a brake (14) will be allowed to prevent further movement of the control surface away from the neutral position. As a result, the control surface is moved to its neutral position with great accuracy and no flutter.

Abstract: The invention relates to the control of a hydraulic jack which can be used, for example, for controlling the orientation of the rear wheels of a vehicle with front guiding wheels. In the event of a failure in the supply of fluid under pressure to the chambers (3, 4) of the jack, these chambers are isolated and the piston (2) is maintained in the position which it occupied when the failure occurred, by means of non-return valves (12). However, when certain conditions are satisfied, for example a sufficiently low speed, the electronic control member (20) activates an auxiliary circuit (30 to 39) in order to return the piston to its middle position and allow driving of the conventional kind with the rear wheels in line.

Abstract: The invention relates to a safety arrangement for a controlled drive which is connected to a conduit with impressed pressure. When the safety arrangement responds the machine is separated via shutoff valves from the inlet and outlet and a via a switchover valve the pivot angle of the machine is set to the maximum value so that the largest possible braking torque can be automatically set.

Abstract: An actuator system is disclosed which modulates a linear output shaft associated with a working control valve or the like in response to a control signal input. The system includes a feedback control link, a pneumatic positioner, a pneumatically controlled hydraulic valving system and a hydraulic cylinder and piston assembly controlled by the hydraulic valving system. The hydraulic valving system includes a three-position, four-way valve actuated by pneumatic binary output signals from a signal conditioner which is in turn controlled by the positioner. Hydraulic flow to the three-position, four-way valve may also be controlled from the signal conditioner in response to positioner output for most effective actuation of the hydraulic cylinder and piston assembly. Failure modes are also disclosed with the present system. The resulting system exhibits extremely rapid response times and high accuracy with dynamic stability.

Abstract: Check device for a redundant flight control apparatus comprising at least two servo drive devices. Failure in supplying fluid and wedging of a control valve (20) can be simulated. Failure of the bypass valve (35) can be checked by reading and comparing the volume flows of the respective pumps as well as by evaluating the travelling rate of the servo drives (1, 2) by the pilot.

Abstract: An actuator system is disclosed which modulates a linear output shaft associated with a working control valve or the like in response to a control signal input. The system includes a feedback control link, a pneumatic positioner, a pneumatically controlled hydraulic valving system and a hydraulic cylinder and piston assembly controlled by the hydraulic valving system. The hydraulic valving system includes a three-position, four-way valve actuated by pneumatic binary output signals from a signal conditioner which is in turn controlled by the positioner. Hydraulic flow to the three-position, four-way valve may also be controlled from the signal conditioner in response to positioner output for most effective actuation of the hydraulic cylinder and piston assembly. Failure modes are also disclosed with the present system. The resulting system exhibits extremely rapid response times and high accuracy with dynamic stability.

Abstract: An electronically controlled pipe fracture safety device for operating devices which are fed by a hydraulic pump and which are actuated by a control slide value by means of hydraulic cylinders. Control lines branch off from lines which lead from the hydraulic pump via a control slide valve to the hydraulic cylinders, the control lines feeding the hydraulic medium to a differential flow monitor, on the piston of which a permanent magnet is fastened. The latter, by means of a reed contact as a result of a pressure difference existing between the control lines, which pressure difference is brought about by damage or fracture of a line, produces a signal in the NOR gate, the latter forming the input of a scoring logic. This signal retransmits a self-holding signal to NAND-gates which form a flip-flop. The self-holding signal causes deenergization of a relay and consequently an interruption of the current flow to the control slide valve and brings about the locking position of the latter.

Abstract: A sealed tank normally receiving air under pressure is connected with respect to a shuttle valve so that when there is an accidental loss of pressure, the air in the tank moves the valve to a position where the high pressure in the tank is applied to an intensifier piston placing a brake or the like in operation. By using a three-way valve in the main supply line the brake may be cycled at will merely by an appropriate turn of the valve.

Abstract: A vehicle has elements providing a fluid pathway to the controlling system of spring actuated, normally locked brakes that are fluid releasable. The elements forming the fluid pathway are connectable to a fluid power assembly that is movable to and from the vehicle and releasably connected to the fluid pathway.