Abstract: An agricultural-implement hydraulic circuit includes a pump supplying pressurized fluid to a first service line and a second service line via a feed line and a device for varying the flow rate of the pump. A distributor valve is disposed between the first service line and the second service line, with the first service line and the second service line being connected and disconnected according to a position of the distributor valve. A hydraulic motor is coupled to the first service line through the valve and discharges fluid to a return line. A hydraulic actuator is coupled to the second service line. An indicator-valve assembly is coupled to the feed line, with the indicator-valve assembly including an indicator sensitive to pressure in the feed line such that the indicator indicates a predetermined pressure in the feed line to an operator.

Abstract: An electro-hydraulic assembly for use in underground mining is disclosed. The assembly includes a hydraulic component, such as a valve block for an underground self-advancing roof support, as well as actuators and/or sensors which have a housing and can be connected or are connected via a data-transmission system to a control unit. A function (e.g. withdrawing the support, setting, advancing, or the like) can be activated at the hydraulic component by each actuator, and/or a hydraulic state associated with a measuring point of the hydraulic component or another measured variable associated with the self-advancing roof support can be measured by each sensor. A reader unit is associated with each actuator and/or sensor in its respective housing, and an information element or transponder is associated with the hydraulic component for each function, each control valve, or each measuring point.

Abstract: The invention relates to an electrohydraulic monitoring device for a dual effect hydraulic cylinder in which certain operating pressures must be maintained. A pressure reduction valve is provided for setting said pressures, this pressure reduction valve being used to set a defined pressure (41) by adjusting the pretension of the valve spring (41). The valve spring is situated in a spring chamber (137) which is bordered by a regulating sleeve (46) on one side, in an axially moveable manner. Said regulating sleeve is displaceable between two end positions within a limited axial stroke area. The alternative switching positions of a micro-switch (117) are linked to these end positions. Two sensor chambers, each of which is connected to one of the pressure chambers of the cylinder in such a way that they communicate, are provided and are delimited by sensor pistons (106, 107) in order to determine the operating pressure that is being coupled into the hydraulic cylinder at a particular time.

Abstract: The present invention provides a single sensor, preferably of a capacitance type, that detects various conditions of a brake booster and the braking system. In one embodiment, the sensor is integrally formed with a reaction disc in the brake booster. Another embodiment includes forming the sensor within the poppet valve of the brake booster.

Abstract: A fluid power operate linear drive possessing a slab housing (2) with an elongated cross sectional outline, in which a plurality of receiving spaces (8) are arranged extending in a common housing plane adjacent to each other in the direction of the longitudinal axis (3) of the cross section. At one first narrow side (21) of the housing there is a piston receiving space (12) extending in the longitudinal direction containing a piston (13) connected with an outwardly running force output part (16). At the opposite second narrow housing side (22) there is an electronic circuitry receiving space (23) containing electronic valve control circuitry (24). Between the piston receiving space (12) and the electronic circuitry receiving space (23) there is at least one valve receiving space (26), which contains a control valve means (25), which is able to be electronically operated and serves for the control of fluid actuation of the piston (13).

Abstract: The invention relates to an axial piston engine (1) with a housing (2), inside the housing interior (4) of which a drive shaft (7) and a cylinder drum (16), arranged axially adjacent to said shaft, are rotatably mounted. The longitudinal mid-axes (9a, 9b) of the driveshaft (7) and the cylinder drum (17) run inclined to each other at an angle (W). Several piston bores (18) are arranged in he cylinder drum (16), running roughly parallel to the mid-axis thereof and in which pistons (21) may run axially up and down. The ends of said pistons, facing the driveshaft (7), are universally pivoted.

Abstract: A hydraulic actuator is disclosed having a cylinder with a piston that is moved by hydraulic fluid. A light guide in one end of the cylinder directs a laser beam into the cylinder, and off the piston where the beam is reflected. The beam then exits the cylinder through at least two light guides connected to two corresponding optical fibers. Each of the optical fibers are joined together into one fiber that carries the reflected beam of light to a photo-diode located remote from the cylinder. A control circuit measures the time of flight of the laser beam.

Abstract: The present invention relates to a vehicle brake system with a pneumatic brake booster which includes an input member being actuated by a vehicle operator and an output member as well as a control housing that carries a movable wall and accommodates a reaction plate at least in part, wherein there is further provision of means for detecting the point of maximum boosting of the pneumatic brake booster that can be used for the actuation of another brake force boosting device. The core of the present invention lies in that a switching or sensor means is provided with senses the maximum boosting force on the basis of a maximum deformation of a reaction element that is indirectly arranged between an output element and a movable wall in that the maximum approach between the output member representative of the output force and the movable wall representative of the booster force is sensed. Further, appropriate means sense the hold time during which the mentioned signal is applied.

Abstract: The present invention provides a single sensor, preferably of a capacitance type, that detects various conditions of a brake booster and the braking system. In one embodiment, the sensor is integrally formed with a reaction disc in the brake booster. Another embodiment includes forming the sensor within the poppet valve of the brake booster.

Abstract: A piston position in a cylinder of a hydraulic assembly is measured using microwave pulses. The microwave pulses are launched along a conductor coupled to the piston or cylinder. A sliding member is slidably coupled to the conductor and moves with the piston or cylinder. Position is determined as a function of a reflection from the end of the conductor and the sliding member. Various aspects include signal processing, fudicial pulse identification control and input/output circuitry, and a three conductor configuration.

Abstract: A piston position in a cylinder of a hydraulic assembly is measured using microwave pulses. The microwave pulses are launched along a conductor coupled to the piston or cylinder. A sliding member is slidably coupled to the conductor and moves with the piston or cylinder. Position is determined as a function of a reflection from the end of the conductor and the sliding member.

Abstract: A linear drive comprising a housing having a tube body (3) and a terminally mounted housing cover (4). In the wall of the tube body (3) a cavity is located, into which a sensor (14) extends. The rear end section (21) of the sensor (14) is in a socket (18), arranged as an extension of the cavity, of the housing cover (4). This socket (18) is formed by a recess (22) and its opening (26) extends from the end face (23) facing the tube body (3), of the housing cover (4) as far as the adjacent lateral outer face (24) of the housing cover (4). The electrical lead means for the sensor (14) are associated with the lateral section of the recess's opening (26).

Abstract: A pressure medium actuated piston-cylinder device comprises at least one magnetically activated sensor (20) for detecting the piston position and which is adjustably attached to the cylinder (10) for indicating, both optically and electrically any desired piston position, wherein the sensor or sensors (20) are mounted in at least one longitudinal channel (17) on the outside of the cylinder (10), and one or more clamping spindles (21) are rotatively supported in and extending throughout the length of the channels (17) and arranged to be rotatively shifted by an activating mechanism (23) between a sensor (20) arresting position and a sensor (20) releasing position.

Abstract: The invention relates to a sensor arrangement (10) for a vacuum brake booster with a brake booster housing comprising at least one vacuum chamber (54) and one working chamber (26), which is separated from the latter by a moveable wall (20) and is connectable either to vacuum or at least atmospheric pressure, as well as a bore (18) disposed in the brake booster housing. The sensor arrangement (10) comprises a first partition (38), which seals the brake booster housing off from the ambient atmosphere when the sensor arrangement (10) is assembled. The sensor arrangement (10) also comprises a housing (12) with a first housing portion (13) which projects into the brake booster housing. The first housing portion (13) is divided by a second partition (40) into a first chamber (44) and a second chamber (46).

Abstract: A contraction unit with a contraction tube (10) that extends between two spaced head pieces (11,12) and that contracts in length when pressure builds up on the inside is proposed, which is provided with a position sensor device for detecting the distance between the head pieces (11,12) based on the expansion of an elastic measurement object (16) with the help of an expansion measurement device (18), wherein the measurement object (16) extends between the head pieces (11,12) or in or on the wall of the contraction tube (10).

Abstract: An intelligent input push rod assembly for applying an input force from a brake pedal to a power booster of a brake system. The input push rod assembly includes a sensor that is capable of generating an electrical output having a magnitude that varies with the amount of force applied to the input push rod by the brake pedal. Preferably, the sensor generates an output voltage signal that is generally proportional to the input force applied to the input push rod. A shunt is provided so that springs associated with the sensor operate in a generally linear force-deflection range of the springs. The output signal generated by the sensor is applied to a brake light control system that is supported by the input push rod assembly. The brake light control system uses the signal generated by the sensor to determine whether the vehicle brake lights should be illuminated and also to cause direct illumination of the brake lights during a braking operation.

Abstract: A piston position in a cylinder of a hydraulic assembly is measured using microwave pulses. The microwave pulses are launched along a conductor coupled to the piston or cylinder. A sliding member is slidably coupled to the conductor and moves with the piston or cylinder. Position is determined as a function of a reflection from the end of the conductor and the sliding member.

Abstract: An attachment structure for a position-detecting sensor includes a sensor attachment mechanism having a rail member which is secured to an outer side surface of a cylinder tube and a holder which holds the position-detecting sensor and which is provided slidably along the rail member, wherein chamfered sections, each of which is chamfered with a predetermined radius of curvature, are formed for the rail member and the holder. As a result, the attachment position of the position-detecting sensor can be arbitrarily adjusted in a stroke direction of a cylinder.

Abstract: A pressure medium actuated piston-cylinder device comprises at least one magnetically activated sensor (20) for detecting the piston position and which is adjustably attached to the cylinder (10) for indicating, both optically and electrically any desired piston position, wherein the sensor or sensors (20) are mounted in at least one longitudinal channel (17) on the outside of the cylinder (10), and one or more clamping spindles (21) are rotatively supported in and extending throughout the length of the channels (17) and arranged to be rotatively shifted by an activating mechanism (23) between a sensor (20) arresting position and a sensor (20) releasing position.

Abstract: A hydraulic actuator is disclosed having a cylinder with a piston that is moved by hydraulic fluid. A light guide in one end of the cylinder directs a laser beam into the cylinder, and off the piston where the beam is reflected. The beam then exits the cylinder through a second light guide. A control unit measures the time of flight of the laser beam and calculates the piston position.

Abstract: A self contained, supplemental vacuum assist unit is provided for use with a vacuum brake booster and a source of vacuum in a motor vehicle. The unit includes, within a single housing, an electric motor, an air pump driven by the motor, a manifold defining air exhaust and assist vacuum chambers, a pair of check valves permitting air flow from the pump outlet and the assist vacuum chamber to the air exhaust chamber, an outlet from the air exhaust chamber with a fitting for connection to the vacuum source, an opening from the assist vacuum chamber with a fitting providing communication directly to the interior of the vacuum chamber of the booster, and a pressure sensor including a diaphragm, plunger, magnet with a Hall effect sensor and motor control circuitry on a circuit board within the assist vacuum chamber. The unit is compact, light weight and efficient and is designed for attachment directly to the booster with no intervening vacuum hose therebetween.

Abstract: A piston-cylinder unit includes a cylinder with a piston rod guide and a piston rod with a piston axially movably mounted in the cylinder so that the piston rod runs through a hole in the piston rod guide. A movement determination device comprising a transmitter portion and a receiver portion determine the movement of the piston from the travel time of waves generated by the transmitter portion. The movement determination device is arranged inside the piston rod guide, and waves reflected by the piston-piston rod component group are analyzed to determine the movement of this component group.

Abstract: A stroke control tool for controlling the position of a subterranean well hydraulically actuated double acting piston and cylinder actuator assembly. The tool includes hydraulic fluid measuring means positioned adjacent the well and is connected to the actuator by relatively inelastic hydraulic lines so that the volume of fluid communicating between the measuring means and the actuator can accurately be measured for determining the position of the actuator.

Abstract: A hydraulic actuating system for movable parts, particularly for hinged covers on vehicles, includes at least one or more working cylinders with a piston equipped with sealing means pressing against the cylinder wall. A control unit is connected with one or all cylinders, and a pressure sensor connected to a control unit. Devices on the cylinder and piston are designed to cause pressure modulation in the cylinder and a common hydraulic circuit. The outgoing signals from the pressure sensor, are changed corresponding to the pressure modulations and are transmitted to the control unit to be used for position control and/or identification of one or all cylinders by the control unit.

Abstract: The invention relates to a control device for hydraulic power cylinders, in particular power cylinders of a road truck tailgate, comprising a hydraulic pump (1) driven by a motor (M). Said pump can be connected to a supply of medium and, via pump branch pipes, to a chamber of the operating cylinder (14) by means of allocated control valves (12,13). An adjustable electrical pressure gauge and switch unit (15-18) is connected to the chamber or corresponding pump branch pipe of the power cylinder. Said unit is fitted with a computer (15) for entering maximum pressure limits and used to stop the pump motor drive (2, 19) and activate a signal transmitter (20) when a preset maximum pressure is exceeded. In addition, a safety valve (22) set at a cut-in pressure lower than the preset maximum pressure is connected to the chamber or corresponding branch pipe (8″,A,B) via an electromagnetic valve (23) which opens when the device is not operating.

Abstract: In a free piston machine, a coil is mounted to its housing and magnetically linked to a permanent magnet or electromagnet on its piston member to form a linear motor. The coil and magnet are either added to embody the invention or are part of an AC linear alternator or AC linear motor which are a part of the free piston machine. A source of DC electrical current and a switch for connecting the DC source to the coil supply DC current to the coil when the switch is closed so that the coil and magnet temporarily operate as a DC linear motor until the piston is adequately centered for start-up without collision. The DC source voltage is temporarily applied to the coil to move the piston away from an end wall of the cylinder. This is accomplished by applying the DC current to the coil for a predetermined time interval, or by sensing when the piston has reached an adequately centered position.

Abstract: A method and apparatus for diagnosing components in high-pressure pumps to indicate when a component of the pump head is malfunctioning and to identify the malfunctioning component. In one embodiment, a high-pressure pump head incorporating a diagnostic system in accordance with the invention has a pressurization chamber and a pressurizing member at least partially received in the pressurization chamber. The pressurizing member moves within the pressurization chamber along an intake action to draw fluid into the pressurization chamber and along a pressurizing action to compress fluid in the pressurization chamber. An inlet fluid control assembly is coupled to the pressurization chamber to allow fluid to enter the pressurization chamber during the intake action, and a pressurized fluid control assembly is coupled between the pressurization chamber and an outlet chamber to selectively allow pressurized fluid into the outlet chamber during the pressurizing action.

Abstract: A device for detecting undesired amounts of gas in a lubricant dispensing system includes a measuring chamber connected to a lubricant dispensing system and configured to receive lubricant therefrom, a moveable rod located at least partially inside the measuring chamber, an actuator operably connected to the measuring chamber and adapted to create at least a partial vacuum in the measuring chamber as the measuring chamber fills with lubricant, and a sensor for detecting a rate of compression or expansion indicative of undesired levels of gas in the lubricant by sensing movement of the moveable rod when the lubricant enters the measuring chamber. The device is constructed to dump charges of lubricant having unacceptable levels of entrapped air, and further includes an adjustment mechanism permitting adjustment without unnecessarily dumping lubricant in the measuring chamber.

Abstract: An end dampened working cylinder for a fluid which serves as a fluid power medium for transmission of energy, the working cylinder comprising a main piston; control plungers carrying ring magnets and mounted on both sides of the main piston; springs form-locking the control plungers with the main piston and piston rod; sensors incorporated in a topside end and a bottom end and reacting to a contactless magnetic field, so that on approaching the ring magnet but at least on reaching a sealing rest position of the control plunger at each of the end stops a signal of a respective one of the sensors is generated and serves for controlling the fluid power, the control plungers sliding along the piston rod so as to provide adjustable and guaranteed sealing, outlet channels and a throttled flow-off channel, the control plungers serving as a shut-off component and valve for the outlet channels, so that when the control plungers rest on the topside end and the bottom end a dampening space is formed, from which a dampen

Abstract: A molded piston includes a base plate, having a plurality of holes, and a polymeric material molded around the base plate and extending through the holes so as to form a mechanical bond between the base plate and the polymeric material. The molded piston preferably includes integral seals in its outer circumferential surface and integral standoffs on its end surfaces. In some preferred embodiments, the molded piston also includes a magnet which creates a magnetic field in the area of the piston.

Abstract: An indication means in a brake cylinder for a vehicle brake with a spring activated parking brake in which the brake cylinder comprises a cylinder housing (3) with a casing wall (22) and at least one gable (23). A pressure spring (5) is positioned between the piston (4) and the gable (23) of the cylinder housing for activating the parking brake by mechanically influencing the piston (4) of the brake cylinder. A bar (11) is axially displaceable relative to the release screw (1) in the throughbore (34) in the release screw (1). The bar (11) at a first end, within the cylinder housing (3), has a position sensing body (8, 16) which is axially fixed to the bar (11) and provided with a contact surface (40) for contact against the nut (7). At a second end the bar (11) has an indication body (12) which visibly protrudes out of the screw head (36) of the release screw (1) in case of axial displacement of the bar (11).

Abstract: A rotating device for a diesel motor comprises a unit having a plurality of pneumatic cylinders that can be brought into mating engagement with teeth on a flywheel of the motor. Each pneumatic cylinder, under the control of a control unit, is actuated and sequentially pushed into the teeth such that a counter-clockwise or clockwise rotation is possible.

Abstract: A piston position sensing system with improved accuracy and reliability is achieved by electromagnetic wave coupling using the combination of: a mechanical structure that in addition to supporting the rod, provides an extension of the resonance cavity, supports the electromagnetic wave couplers and a hydraulic fluid input-output port into the extended cavity and a piston travel stop; an electronic circuitry shielded package having a high frequency section with coaxial shielded input and output conductors on opposing package sides and a lower frequency counting section having a piston position output shielded conductor and a fluid dielectric property change monitor input conductor separated from the high frequency section conductors; and, the positioning of the electronic package on the mechanical structure with the coaxial shielded input and output conductors respectively adjacent to the input and output couplers and with the hydraulic fluid input-output port positioned elsewhere around the periphery of the c

Abstract: A pneumatic actuating arrangement with a plurality of consumers (1) having working areas (7,8), a plurality of feed air/signal distributors (13) connected to a common pressure source and a common control unit (19), a plurality of electrically-actuated switching devices respectively arranged directly at the consumers (1) forming separate consumer units (9), and a combination line (12) extending between each consumer unit (9) and a feed air/signal distributor (13), each combination line including a supply pressure line for supplying air to the working areas of a respective consumer and electrical signal lines for connecting the electrically-actuated switching devices of a respective consumer unit to said common control unit.

Abstract: A device and method for selecting a control mode in a power construction vehicle is disclosed. The device has a control mode select switch which selects a function for setting new matching relations between the control levers and the proportional control valves. A controller sets the new matching relations and stores the new matching relations, and controls the actuators in accordance with the new matching relations. In the control mode selection method, one operational motion of an actuator is primarily selected and displayed on a display means. Thereafter, a voltage signal indicative of a levering angle of a control lever associated with the selected actuator is output, thus setting a new matching relation between the control lever and an associated proportional control valve. The above process is repeated in order to continuously set and store new matching relations between the control levers and proportional control valves associated with the other actuators.

Abstract: An alarm device, an improved squeeze-pad hydraulic system for a squeeze truck, and a method for converting an existing squeeze-pad hydraulic system of a squeeze truck into a squeeze-pad hydraulic system that alerts the operator of the squeeze truck when dangerously high hydraulic pressures are approached within the squeeze-pad hydraulic system are described. The alarm device comprises: an alerting device, operationally responsive to an electrical signal, having an input terminal for receiving the electric signal, and an alarm threshold switch comprising: a pressure transducing element in fluid communication with the hydraulic lines in a manner such that hydraulic fluid within the hydraulic fluid lines will exert a pressure on the pressure transducing element, and an electrical switching device, in electrical connection with the input terminal, for directing the electrical signal to the input terminal.

Abstract: The ability to be able to identify, distinguish and verify a lock onto harmonic frequency signals in the oil of a hydraulic cylinder using a ratio between consecutively detected harmonics. The identification is useful in providing early and reliable harmonic resonance "lock on" and the ability to "lock on" to a particular order harmonic resonance.

Abstract: A pneumatic or hydraulic cylinder assembly (10) includes a cylinder (10), a piston (12) axially slidable within the cylinder (10), and structural elements are disposed within the cylinder (10) to issue a piston (12) position signal in response to the piston reaching a predetermined position.

Abstract: The apparatus is an oscillator for a showerhead to keep the forming fabric of a papermaking machine clean and open. A hydraulic cylinder is formed with a piston cup assembly dividing the cylinder into first and second fluid chambers. The piston cup assembly is coupled to a magnet and a driveshaft, the driveshaft being coupled, in turn, to the showerhead to be oscillated. A four-way valve is used to direct fluid from a pressurized external source alternately into said first and second fluid chambers thereby causing reciprocation of the driveshaft. The position of the magnet, and hence the driveshaft and showerhead, is monitored by a transducer which sends position and rate signals to a microprocessor-based controller. The microprocessor-based controller sends a signal to the four-way valve to direct which of said first and second fluid chambers receives fluid from the pressurized source in order to achieve the desired parameters of reciprocation.

Abstract: A pressure regulating circuit in which the piston of a pneumatic cylinder can attain a balanced condition without requiring any adjustment to a workpiece. In the pressure regulating circuit, the pressure in an oil pressure chamber of a pressure reducing valve equals the pressure in a pressure sensitive oil chamber of a workpiece retention member. The pressure in a pressure sensitive chamber of the pressure reducing valve equals the pressure in the oil pressure chamber. Therefore, the pressure in a piston pressure chamber of a main valve connected to the pressure sensitive chamber equals the pressure in the pressure sensitive oil chamber. When the pressure in a control chamber of the main valve and the pressure in a working chamber of a pneumatic cylinder are respectively balanced with the pressure in the piston pressure chamber, the piston P can attain a balanced condition.

Abstract: An auto cycle pump in accordance with the invention includes a housing having a reservoir for storing hydraulic fluid. A hydraulic pump in the housing provides hydraulic flow. A directional valve has neutral, advance and retract positions to respectively restrict hydraulic flow, direct hydraulic flow to an advance port and direct hydraulic flow to a retract port, the ports for hydraulic connection to the hydraulic tool, in use. Fluid conduits are provided connecting the pump and reservoir to the directional valve. A flow switch detects return flow from the directional valve to the reservoir. A pressure sensor sense hydraulic pressure from the pump. A dump valve is operatively connected to the pump for directing hydraulic flow back to the reservoir when the directional valve is in the neutral position. A control is operatively connected to the pump, the directional valve, the flow switch and the pressure sensing means for controlling operation of the auto cycle pump in automatic mode of operation.

Abstract: The main feature of the differential pressure detecting system of the present invention resides in that, when a mechanical arm is to clamp a workpiece, a differential pressure can be produced for operating a cylinder and in turn triggering a responsive switch to activate a display device; when it clamps the workpiece, the differential pressure still exists for maintaining the said activating, when it clamps nothing, the cylinder will be restored and in turn turn off the responsive switch to turn off the display device.

Abstract: Dynamic gain adjustment in hydraulic piston position sensing that continuously accommodates for changes in signal level is provided by attenuating the gain of the sensing system through a comparison of a measured value with a stored value at each piston position.

Abstract: A differential pressure control switch system for use in determining the relative position of a piston in a pneumatic cylinder in relation to a pre-set threshold pressure sensing by the differential in the supply side and exhaust side of a double acting pneumatic cylinder and a four-way directional control valve associated therewith.

Abstract: A shaft is provided with a low speed oscillating progressive drive by means of hydraulic cylinders which operate a lever mechanism which may be clutched to and declutched from, the shaft. A pneumatic control system senses the position of the pistons of the hydraulic cylinders and provides a controlled oscillation of the cylinders. When the pistons cause the shaft to rotate in one direction a sensor causes the lever mechanism to be declutched from the shaft after a selectable number of degrees of rotation. The pistons continue their stroke to the normal limit where the lever mechanism is caused to be once more clutched to the shaft. This operation is continued producing an oscillatory progressive rotation of the shaft.

Abstract: A contacting and sealing structure, for electrical continuity, noise reduction and leakage reduction between parts that move in relation to each other at the ends of the cavity within a hydraulic cylinder employing electromagnetic wave position sensing, is provided by employing two springs having garter and canted coil spring functions that are retained in side by side grooves in one of the parts so that the spring coils extend directly across the intersection of the parts.

Abstract: A single rod three chamber fluid cylinder is driven in an initial rapid advance forward stroke by a main pump, pumping fluid through a proportional directional control valve to act against a first equal area at the head end of the piston. Fluid expelled from a second equal area at the rod side of the piston is returned to the reservoir through a proportional directional control valve which is in a first position while a two position valve is in its first position allowing an accumulator to fill a third chamber exposed to a third area of the head side. When shifting to the feed stroke, the two position valve switches to its second position disconnecting the accumulator to the third area and connecting the main pump to the third area while also connected to the first equal area. Upon the return stroke of the piston, the fluid from the first equal area is returned to the sump and the fluid from the third area is routed to the accumulator.

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: A hydraulic system has a pump (1) with at least one load (4, 5) and accompanying bi-directional valves (8, 8a). A first comparator (A) establishes which motor line (6, 7) is carrying the higher load pressure. A second comparator (B) establishes whether the input-side motor line (6, 7) allocated a directional signal identifying the direction of the valve displacement is carrying the higher pressure or whether a load (4, 5) is being operated with negative loading. Depending on the result of the comparison, the load pressure signal (y1, y2) can be processed differently.

Abstract: This operating mechanism for a hydraulic actuator (2) having a pressure-proportional actuating signal is provided with an amplifier (33) for electric signals, with at least one electrohydraulic transducer (24) connected upstream of the hydraulic actuator (2) and with a hydraulic discharge amplifier connected between the electrohydraulic transducer (24) and the actuator (2). The aim is to provide an operating mechanism for a hydraulic actuator having a pressure-proportional actuating signal which can be produced simply and cost-effectively. This is achieved by interconnecting between the actuator (2) and the hydraulic discharge amplifier a piston/cylinder arrangement (4) acting as a transducer.