Abstract: A system for determining the extended length or orientation of a hydraulic actuator, or of an implement or joint, is disclosed herein. Electromagnetic (EM) bursts such as ultra-wideband or frequency pulses are generated and applied to a transmitter unit attached to a stationary or moveable portion of the actuator. The EM bursts are launched by the transmitter toward a receiver located on the other of the stationary or moveable portion of the actuator. The time for the EM bursts to travel between the associated antennas of the transmitter and the receiver is determined and converted into a position signal representing the distance therebetween.

Abstract: An actuator employing an electromagnetic voice coil actuator in parallel with a pneumatic actuator in a single, integrated unit. Rolling diaphragms on the piston are used to minimize sliding static friction. The pneumatic portion of the actuator provides the high forces necessary to support a heavy load and does not become stiff at high frequencies. At high frequencies (above 15-20 Hz.), where the frequency response of the pneumatic portion of the actuator decreases, the voice coil portion takes over and provides the desired high frequency actuation forces. The voice coil does not require a large amount of electrical power, and air flow in the pneumatic actuator provides sufficient cooling of the voice coil. A servo-valve is also disclosed for use with the pneumatic portion of the electro-pneumatic actuator.

Abstract: A bellows has a first portion that is formed with a hollow protrusion and can be actuated by pressing on it and a second portion formed with an annular wall defining an opening. The hollow protrusion fits within the opening. Actuation of the first portion causes a fluid to flow through the hollow protrusion and opening, and the fluid tends to force the protrusion against the annular wall. In another embodiment, the first and second portions are sealed along planer front and rear walls. A nut us provided having teeth for clamping the device to an air tube. The bellows can be used to control any device, including a pressure switch, valve or gauge, that is controlled by a change in fluid pressure applied thereto.

Abstract: A fluid cylinder assembly for a work machine includes a fluid cylinder having a housing which includes a first end wall, a second end wall, and a cylindrical side wall which collectively cooperate so as to define a piston chamber. The fluid cylinder also includes a piston housed for translation within the piston chamber, and a rod which extends through an opening defined in the second end wall. An ultrasonic transducer is secured to the cylindrical side wall of the fluid cylinder for transmitting ultrasonic vibrations into the piston chamber during a first time period and receiving ultrasonic vibrations from the piston chamber during a second time period. A control circuit is operatively coupled to the transducer. The control circuit generates a trigger signal which causes the transducer to transmit the ultrasonic vibrations during the first time period. The control circuit analyzes returned energy or echoes from within the piston chamber in order to determine piston location within the piston chamber.

Abstract: A low friction fluid motor has a diaphragm mounted in a shell to divide the shell into first and second chambers, a port means for connecting the second chamber to a pressure or vacuum source, and an actuator assembly. The actuator assembly is connected to the diaphragm and includes an actuator member extending out of the shell through an aperture. The actuator is free of any seal member which is interposed between the actuator member and the shell and which functions to form a seal between the actuator member and the aperture in the shell. The aperture is oversized relative to the actuator member to allow free passage of the actuator member from the actuator assembly through the first chamber and out of the fluid motor.

Abstract: A pneumatic or hydraulic cylinder (1) includes a cylinder tube (3) consisting of a non-ferromagnetic material in which a piston moves. At least one longitudinal channel (9) is recessed in the outer surface of the cylinder tube in which a signal transmitter (8) is secured to scan the piston location without physical contact. A permanent magnet is located on the piston which activates the signal transmitter (8) by its magnetic field. A leaf spring (17) is provided to secure the signal transmitter (8) in the longitudinal channel (9) and is attached to the housing of the signal transmitter by means of a screw (12) and a nut (19) with an inclined surface (20) that moves outward against the wall of the longitudinal channel (9) when the screw is tightened and thus tightly clamps the signal transmitter (8). The attaching device, consisting of the screw (12) with nut (18) and leaf spring (17), and the signal lead (10) are positioned on the same end of the signal transmitter (8).

Abstract: An arrangement is provided for determining the relative angular orientation between an excavator bucket and the dipper stick of an excavator. The excavator bucket is mounted on a bucket linkage that is pivotally secured to the end of the dipper stick. An hydraulic actuator has an hydraulic cylinder pivotally connected to the dipper stick, and a piston pivotally connected to the bucket linkage. Extension or contraction of the hydraulic actuator causes the excavator bucket to be pivoted by the bucket linkage with respect to the dipper stick. A cable extension linear position transducer having a transducer casing, a sheath extending from the casing, and an extensible cable extending from the sheath, provides an electrical output related to the extension of the cable from the sheath. A transducer mounting secures the casing of the cable extension linear position transducer in fixed relationship to the hydraulic cylinder. A clip secures the extensible cable to the piston.

Abstract: A friction clutch arrangement for motor vehicles to control a clutch friction disk rotationally mounted on a transmission shaft which can be locked between two components has a clutch actuating device which includes a slave device adjacent to the clutch, a master device remote from the clutch and a force transmission system between the two devices. The slave device has an annular housing having an axial extension with a radially outer part and a radially inner part which are arranged concentrically to form an annular space containing a movable piston which is engagable with the clutch friction disk. A piston sensor in the radially inner part of the axial housing extension makes it possible to determine the position of the piston in the slave cylinder independently of external influences such as vibrations or dirt or of the influence of neighboring components.

Abstract: A friction clutch arrangement for motor vehicles to control a clutch friction disk rotationally mounted on a transmission shaft which can be locked between two components has a clutch actuating device includes a slave device adjacent to the clutch, a master device remote from the clutch and a force transmission system between the two devices. The slave device has an annular housing having an axial extension with a radially outer part and a radially inner part which are arranged concentrically to form an annular space containing a movable piston which is engagable with the clutch friction disk. A piston sensor sealed in the radially outer part of the axial housing extension makes it possible to determine the position of the piston in the slave cylinder independently of external influences such as vibrations or dirt or of the influence of neighboring components.

Abstract: A cylinder device includes a casing with a pair of fluid inlet/outlet ports defined therein, a base plate, a piston fixed to the base plate, a cylinder, and a top plate. The cylinder device also has first, second, and third cylinder chambers defined in the cylinder between the base plate, the piston, and the top plate, a first fluid passage and a second fluid passage through which one of the fluid inlet/outlet ports communicates with the first and third cylinder chambers, and a third fluid passage and a fourth fluid passage through which the other fluid inlet/outlet port communicates with the second cylinder chamber.

Abstract: The identification of and compensation for changes in the dielectric properties of a hydraulic fluid in hydraulic apparatus is achieved by continuously sampling a hydraulic fluid in a resonant chamber with a central conductor that is both inductively and capacitively coupled to an oscillator. The output frequency changes of the oscillator is an indicator of changes of the dielectric properties of the hydraulic fluid and their magnitude. The invention is of particular value in hydraulic cylinder piston position determining systems.

Abstract: A system for determining the position of a piston moveable within a cylinder, or of an implement or joint, is disclosed herein. Electromagnetic (EM) bursts such as ultra-wideband or frequency pulses are generated and applied to a transmitter/receiver unit. The EM bursts are launched by the transmitter along a transmission guide from an end of the cylinder housing towards the piston. The transmission guide can be a dipstick mounted within the cylinder housing or the cylinder housing itself. The dipstick or cylinder housing is in electrical communication with the piston such that a surface of the piston represents an electrical impedance discontinuity which causes the EM bursts to be reflected back to the receiver. The time for the EM bursts to travel from the transmitter to the piston and for the reflections to travel back to the receiver is determined and converted into a position signal representing the piston's position.

Abstract: An improved rotational displacement apparatus is provided for measuring accurately the twist induced in an extension-twist coupled specimen in response to application of an axial load. The apparatus has an internal cylinder within which a piston rides. A piston rod extends from the piston through a pair of radial ball bearings in the base of the cylinder block to a free end outside the cylinder block. The piston is sized to be slightly smaller in diameter than the cylinder to provide a small space between the piston and the cylinder walls. A part for supplying compressed air to the region of the cylinder below the piston and a part for venting air from the region of the cylinder above the piston are provided. An optical encoder is coupled to measure rotational motion of the piston within the cylinder. In use, the apparatus is mounted in a testing machine and a specimen to be tested is secured at one end to the free end of the piston rod and at its other end to the mounting block of the testing machine.

Abstract: A bellows has a first portion that is formed with a hollow protrusion and can be actuated and a second portion formed with an annular wall defining an opening. The hollow protrusion fits within the opening. Actuation of the first portion causes a fluid to flow through the hollow protrusion and opening, and the fluid tends to force the protrusion against the annular wall. In another embodiment, the first and second portions are sealed along planer front end rear walls. A nut is provided having teeth for clamping the device to an air tube. The device can be used in hot tubs, saunas, on vending machines, and has many medical uses.

Abstract: A linear thruster is disclosed in which a load beam is linearly moved by fluid power relative to a guide beam and a piston. The beams are multisided in cross-section to substantially increase the linear bearing area between the bodies and, thereby, substantially increase the strength of the linear thruster against side forces as well as moments to which the linear thruster might subjected. Internal positioning of the components and energy transmission are maximized and the stroke may be variably adjusted.

Abstract: An actuator for a gear shifting mechanism of a motor vehicle has a housing with pressure chambers and one connector opening into each pressure chamber for supplying a pressure medium into the pressure chambers. A control member is positioned in the housing so as to be axially displaceable in the housing by the pressure medium into different switching positions. A first and second auxiliary piston are supported on the control member and displaceable relative to the control member by the pressure medium. The first auxiliary piston has a first end facing away from the second auxiliary piston, the first end of the first auxiliary piston having a first abutment. The second auxiliary piston has a first end facing away from the first auxiliary piston, the first end of the second auxiliary piston having a first abutment. The first auxiliary piston delimits at least partially the first pressure chamber and the second auxiliary piston delimits at least partially the second pressure chamber.

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 hydraulic actuator for a gate valve incorporates an eddy current proximity sensor to detect a displaceable stem cap made of ferromagnetic material. The stem cap is mounted on one end of an actuating stem. The other end of the stem is coupled to a plunger having a cammed tip which meets a cam attached to the piston. The camming action moves the stem cap from a position out of proximity to a position in proximity to the eddy current proximity sensor when the piston is at the end of its stroke. The proximity sensor is mechanically coupled to the stem housing by means of a housing cap, a barrel and a sensor cap, all made of non-magnetic material. The barrel is threaded at both ends with opposing threads so the barrel can be screwed onto the housing and sensor caps at the same time, thereby drawing the housing and end caps toward each other without sensor rotation. This feature allows the proximity sensor to be positioned at the correct distance from the stem cap without damage to the sensor connector wires.

Abstract: A system for determining the position of a piston moveable within a cylinder, or of an implement or joint, is disclosed herein. Electromagnetic (EM) bursts such as ultra-wideband or frequency pulses are generated and applied to a transmitter/receiver unit. The EM bursts are launched by the transmitter along a transmission guide from an end of the cylinder housing towards the piston. The transmission guide can be a dipstick mounted within the cylinder housing or the cylinder housing itself. The dipstick or cylinder housing is in electrical communication with the piston such that a surface of the piston represents an electrical impedance discontinuity which causes the EM bursts to be reflected back to the receiver. The time for the EM bursts to travel from the transmitter to the piston and for the reflections to travel back to the receiver is determined and converted into a position signal representing the piston's position.

Abstract: The present invention is intended to provide an apparatus capable of detecting an air tube-detached state when said air tube has been detached from an air-actuated valve in order that the same air-actuated valve is caused to assume a closed state. The present invention relates to an air tube connection state detecting apparatus 10 for detecting whether the fore end of an air tube 56 for supplying compressed air to an air-actuated valve 16 for a gas container 12 is connected to said air-actuated valve 16 or not. The air tube connection state detecting apparatus comprises a to-be-contacted member 82, provided at a predetermined position separate from said air-actuated valve 16, to which the fore end of said air tube 56 is to be connected; and a detection means 86 for detecting that the fore end of said air tube 56 is connected to said to-be-connected member 82.

Abstract: A linear actuator comprising a guide section formed along a longitudinal direction to protrude on a bottom surface of a slide table, a pair of guide blocks formed mutually opposingly and seperated from each other by a predetermined spacing distance on an upper surface of the main cylinder body, attachment holes for attaching the main cylinder body to another member in any direction of attachment from a side of the slide table or from a side of the main cylinder body, and an adjuster bolt for adjusting an amount of displacement of the slide table.

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: Pressure medium actuated control cylinder for wear compensation. A cylinder chamber includes two displaceable pistons. One piston has a first piston rod which extends outside the cylinder, and a second piston rod which extends into a through-bore in the second piston. The second piston rod has a bore, into which a rod-shaped resistor extends and penetrates an annular current collector fixed in the bore. The resistor and the current collector form a position sensor in the form of a linear potentiometer which indicates the position of the piston in the cylinder.

Abstract: A cylinder apparatus includes a base plate, a piston fixed to the base plate and having a piston head and a piston rod connected thereto, a cylinder body having a cylinder chamber defined on one side of the piston head and a cylinder chamber defined on another side of the piston head around the piston rod, the cylinder body being supported for reciprocating movement with respect to the base plate in axial directions of the piston, an upper plate fixed to the cylinder body, and a bushing held in slidable contact with an outer circumferential wall surface of the cylinder body for guiding the reciprocating movement of the cylinder body.

Abstract: A rotary hydraulic actuator including a sealed vessel including brackets and a casing, a partition vane attached to a shaft supported by the brackets for dividing an inside of the sealed vessel into a first pressure chamber and a second pressure chamber and pivoting the shaft by a pressure difference between the first and the second pressure chambers, suction and exhaust hydraulic ports and a drain port installed to the casing, a hydraulic control valve mounted to the casing for conducting a hydraulic control along with the suction and exhaust hydraulic ports and the drain port, groove-like hydraulic pressure supply paths installed to a face of one of the brackets in contact with the casing for communicating the first pressure chamber and the second pressure chamber respectively to the suction and exhaust hydraulic ports and a groove-like drain path installed to a face of other one of the brackets in contact with the casing for communicating to the drain port.

Abstract: A piston for a fluid power cylinder, which possesses two separate piston parts, which are detachably set together in a joint region axially with a sealing action. Each piston part has a rigid carrying element, which is molded on a holding portion, which in its radially outer region has a lip seal comprising sealing material with rubber-elastic properties and serving for sealing on a piston running face. The respective lip seal and the holding portion associated with same are constituted by components of an integral elastic body comprising a sealing material with rubber-elastic properties. Such elastic body is molded on the respectively associated carrying element. The two elastic bodies are in sealing contact with one another in the joint zone.

Abstract: A fluid meter assembly in which a housing is provided that has two enclosures formed therein. At least one cylinder is formed in each enclosure and receives a piston. Fluid is admitted into each cylinder to drive its piston and pass the fluid through a corresponding outlet in the corresponding enclosure to enable the fluid flow to be metered.

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: An actuator cylinder for the engagement and release of the friction clutch of a motor vehicle is described. The actuator has a device to indicate clutch engagement position, which is located outside the cylinder. A piston is disposed within the actuator cylinder. The piston has an actuator rod which extends through a cylinder end to operate a clutch. The device to detect the engagement position of the clutch is designed to adjust to the range of movement of the piston, which range of movement changes with clutch wear. The detection device is a displacement transducer. A housing, in which the transducer is mounted, moves as the range of motion of the piston changes with clutch wear. A rod or sensor mounted on the piston both interacts with the transducer to indicate the clutch engagement position and moves the housing of the transducer.

Abstract: A fluid operated rotary drive, which possesses a drive means having an output drive shaft able to be driven for oscillating motion. On one axial side of the drive means a position detection means is arranged, which possesses an actuating member connected with the output drive shaft and which on rotary motion of the output drive shaft performs an oscillating movement about a pivot axis. The actuating member cooperates with sensors, which may be set on holders. Each holder is arranged on its own setting ring, such setting rings being arranged coaxially in relation to each other with the holders extending away from the drive means. The setting rings are able to be turned in relation to one another and furthermore in relation to the housing for setting the positions to be detected and may be fixed in the settings made.

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 fluid meter in which a crankcase and two axially-aligned cylinders are defined in a housing. A crankshaft is disposed in the crankcase and two pistons are respectively mounted in the cylinders for reciprocal movement. Two connecting rods respectively connect the pistons to the crankshaft for rotating the crankshaft in response to the movement of the pistons. A portion of each of the connecting rods engage the other connecting rod to support and guide the connecting rods during the movement.

Abstract: A cylinder apparatus includes a base plate, a piston fixed to the base plate and having a piston head and a piston rod connected thereto, a cylinder body having a cylinder chamber defined on one side of the piston head and a cylinder chamber defined on another side of the piston head around the piston rod, the cylinder body being supported for reciprocating movement with respect to the base plate in axial directions of the piston, an upper plate fixed to the cylinder body, and a bushing held in slidable contact with an outer circumferential wall surface of the cylinder body for guiding the reciprocating movement of the cylinder body.

Abstract: A spring break actuator (10) with a cast aluminum adapter (74) partially defining tandem spring brake and service brake portions has several corrosion fuses on the adapter. Each corrosion fuse is defined by a recessed or thinned area which does not compromise the structural integrity of the adapter.

Abstract: A pistonrod-less linear drive, whose housing having a longitudinal slot contains a drive part for longitudinal movement therein. A transmission member linked with the drive part projects right through the longitudinal slot to the outside. Adjacent to the two flanks of the longitudinal slot there is a respective resistance strip which extends in the longitudinal direction of the slot and is secured to the housing. A wiper contact arrangement is provided on the transmission member which simultaneously makes contact with both resistance strips and on longitudinal movement of the transmission member slides along the resistance strips. Connection means are provided to render possible connection of the two resistance strips with a position detecting and evaluating device.

Abstract: An air-operated combination diaphragm spring brake has a service chamber in tandem with a spring chamber. The service chamber being separated into an upper and lower section by a first elastomeric diaphragm. The spring chamber is separated into upper and lower sections by a second elastomeric diaphragm. A lever type stroke indicator is positioned within either or both the lower sections of the service chamber and the spring chamber.The stroke indicator in the service chamber pivots about a pin when contacted by a plate associated with the service push rod when the brakes are applied, resulting in a portion of the stroke indicator to extend beyond the periphery of the service chamber housing and provide a visual indication of the need to inspect the brake system.

Abstract: A fluid meter is disclosed which comprises a body having a crankcase portion and two axially-aligned cylinder portions. The first and second cylinder portions each have an inner end in fluid communication with the crankcase portion, and respective first and second head ends opposing the inner ends. A crankshaft is rotatably mounted in the crankcase portion and includes two crank pins radially offset from the crankshaft and angularly spaced sixty degrees apart. Pistons are reciprocally mounted in the cylinder portions and are drivingly connected to the crank pins so that rotation of the crankshaft is effected by reciprocation of the pistons within the cylinders. First, second, and third ports are provided having fluid communication with the respective first head end, the second head end, and the crankcase portion. A rotary valve is provided having inlet and outlet ports arranged to sequentially register with the first, second, and third ports when the crankshaft is rotated.

Abstract: An indicator device for signalling that the wear limit has been reached for servo-operated clutches, particularly for motor vehicles. A servo housing comprises a servo piston, which can be moved forward and backward therein for disengaging and engaging the clutch respectively, and the servo piston's rest position, i.e. the position in which it is located when the clutch is engaged, in the event of an increase in clutch wear is gradually moved towards the rear end wall of the housing. The servo housing further comprises a control valve which controls the supply of pressurized fluid to a cylinder space which is located between the servo piston and the rear end wall.

Abstract: Disclosed is a rotary actuator utilizing magnetic screws which are stably rotatable at a great torque with little torque variation. The rotary actuator comprising (a) a closed hollow cylinder, a piston sliding within the cylinder, and a rotary shaft which rotates with the sliding of the piston, has (b) a first magnetic screw member which makes a linear motion in synchronism with the sliding of the piston, and is provided with a first spiral magnetized band, and (c) a rotary shaft rotatably supported in relation to the first magnetic screw member, and having a second magnetic screw provided with a second spiral magnetized band. (d) With the sliding of the piston, the second magnetic screw receives the magnetic force from the first magnetic screw to thereby rotate the rotating shaft.

Abstract: A rotational position detector device (20), which is fastenable to a rotary actuator (1) of the type comprising a rotary motor (3,5) inside a housing (2) and a rotary shaft extending therefrom, a turning element (21) adapted to be rotationally fastened to the rotary shaft, said turning element being detectable by at least one position sensor (23), which is adapted to be adjustably fixed with respect to the housing (2). The device is provided with a socket portion (25) which is rigidly connected to the housing and coaxial with said shaft and at least one sensor holder (24) which is rotatably attached to said socket portion and adjustably fixable in chosen angular positions by means of locking cooperation between a resilient engagement means (26,27) on the sensor holder and a surface (30) which is provided with engagement irregularities.

Abstract: A bottoming detector for detecting the movement of a pump shaft beyond a pre-determined distance within a cylinder is disclosed. The pump has a housing defining an elongate cavity filled with fluid, a resilient sheet with an aperture in alignment with the cavity which divides the cavity into first and second compartments, and an elongate shaft disposed within the first compartment of the cavity such that it may be moved into and out of the aperture in the sheet to cause pressure fluctuations in the second compartment. There is also a chamber in fluid communication with the second compartment. In the chamber there is actuating means responsive to excessive pressure in the chamber, that actuates a switch to indicate that the shaft has reached a certain distance into the second compartment.

Abstract: A linear actuator has an actuator body having a through hole defined axially therein and an opening defined in an upper surface thereof, a pair of end blocks, a slide table reciprocally movable in the directions indicated by the arrows X, Y, a pair of cylindrical members coupled to the end blocks, respectively, and having respective passages communicating with fluid outlet/inlet ports, respectively, defined in the actuator body, a joint member movable in unison with the slide table, a pair of cover members held in surface-to-surface contact with the joint member in confronting relation to each other and hermetically surrounding outer circumferential surfaces of the cylindrical members, for sliding displacement in unison with the slide table, and a pair of pressure chambers defined by the cylindrical members and the cover members and closed by the cover members, the pressure chambers communicating with passages in the cylindrical members.

Abstract: Improvement of the ability to detect selected resonant frequencies associated with the position of the piston in a piston position sensing system using electromagnetic waves in the fluid in a hydraulic cylinder is achieved by positioning the electric signal input and output probes with 90 degree separation around the circumferential periphery of the cylinder to suppress coupling into unwanted modes that diminish detectability of particular resonant frequency signals, In a coaxial sensing system "dummy" probes at 90 degree separation to each other and 90 degree separation to the input and output probes operate to improve symmetry and resonance shape and to suppress unwanted modes.

Abstract: A fluid-powered rotary actuator for providing rotary movement between first and second external members. The actuator includes a cylindrical body with first and second ends. The body is adapted for coupling to the first external member, and a shaft extending generally coaxially within the body and supported for rotation relative thereto. The shaft having an adjustable end limit of rotation relative to the body. The shaft has an end portion adapted for coupling to the second external member to provide rotational movement between the first and second external members. An annular body insert is positioned coaxial with the body and at least partially within the body at the body first end. The body insert is formed as a separate part from the body and is adjustably rotatable relative to the body to permit adjustment of the end limit of rotation of the shaft relative to the body. The body insert is restrained by the body against axial movement relative to the body during powered operation of the actuator.

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 sensor has a magnetic circuit and an electric circuit for scanning the passage of magnetizable and non-magnetizable material of relatively movable parts. The sensor has a housing made of first and second parts which define an interface between them. The first part of the housing can be mounted to a cylinder wall and includes a portion of a magnetic core. A remaining portion of the magnetic core is embedded in the second housing part and an electric circuit operatively coupled with the magnetic core is mounted entirely in the second housing part so that the interface between the housing parts is free of electrical contacts to thereby prevent signal degradation due to contamination of electrical contacts.

Abstract: A fluid power cylinder whose piston rod has on its outer periphery at least one axially extending surface section having the form of a flat. Such surface section has a longitudinal groove, which contains a magnetic strip able to be scanned by a sensor device on the housing. The magnetic strip has alternatingly arranged poles areas in succession, which can be scanned without contact by the sensor device. The magnetic strip is covered by a cover band fixed on the piston rod and consisting of a material allowing the passage of a magnetic field, whose external surface facing away from the magnetic strip constitutes at least a part of the piston rod's surface section having the form of a flat.

Abstract: A coaxial capacitor contacting and sealing structure, for electrical continuity between parts that move in relation to each other at the ends of a cavity within a hydraulic cylinder employing electromagnetic wave position sensing. The structure employs a contacting and sealing member having a high surface conductivity that is mounted in one of the parts. The mounting of the contacting and sealing member provides force for pressure contact in oil between the parts and to enhance electrical continuity with the part in which the contacting and sealing member is located.

Abstract: A combined sensing and barrier element is provided. This sensing element is most useful as a flexible diaphragm which is also described herein. The flexible diaphragm has a resilient elastomeric body and a sensing element having at least one conductive component and at least two nonconductive components such that the conductive component is positioned between the nonconductive components. A change in electrical resistance is recorded by an electrical monitoring device that is electrically connected to the conductive component. By observing changes in the resistance that deviate from a predetermined norm, significant wear of a diaphragm can be determined prior to its failure.