A radial piston pump has a plurality of cylinders within which pistons reciprocally move. Each cylinder is connected to a first port by an inlet passage that has an inlet check valve, and is connected to a second port by an outlet passage that has an outlet check valve. A throttling plate extends across the inlet passages and has a separate aperture associated with each inlet passage. Rotation of the throttling plate varies the degree of alignment of each aperture with the associated inlet passage, thereby forming variable orifices for altering displacement of the pump. Uniquely shaped apertures specifically affect the rate at which the variable orifices close with throttle plate movement, so that the closure rate decreases with increased closure of the variable orifices.

A liquid flow rate control valve is provided in which since a total area of overlapping sections of a communication hole group (38c, 38d) of a distributor (38) and an outlet opening (37a, 37b) of a sleeve (37) changes when the distributor (38) is rotated by a first electric motor (46), if a rotor (42) is rotated by means of a second electric motor (47), an input port (31e) communicates with an output port (31f) through an inlet opening (42c, 42d) of the rotor (42), the communication hole group (38c, 38d) of the distributor (38), and the outlet opening (37a, 37b) of the sleeve (37) when the inlet opening (42c, 42d) of the rotor (42) passes through the overlapping sections, thereby making it possible to carry out PWM control of a flow rate of liquid. Since a thrust load in an axis (L) direction does not act on the distributor (38) and the rotor (42), supporting the distributor (38) and the rotor (42) becomes easy, thereby enabling the cost and weight to be cut.

The invention relates to a method for constructing a gas-filled double-acting hydraulic cylinder (1) with gas spring action, comprising: —a cylinder sleeve (3) with a cylinder bottom (3a) and cylinder head (3b) —a piston/piston rod assembly (5) a hydraulic fluid seal on the piston (9) —a connection for the head-side chamber (13) to a hydraulic line; —a connection for the bottom-side chamber (15) to a hydraulic line, —a gland (20) with a bore, the gland being attached between the cylinder bottom (3a) and the piston (9), the piston rod (7) extending over the entire stroke of the piston rod through the bore, wherein the gland comprises two seals —(25), one for providing a seal with the cylinder sleeve (3) and one for providing a seal with the piston rod.

A system comprises a first piston comprising a first piston shaft and a first drive pin. A first piston cylinder comprises a first body and a first groove, wherein the first groove defines a first aperture, the first aperture oriented axially along the first body and configured to receive the first drive pin. The first body encloses the first piston and allows the first piston to travel axially within the first piston cylinder. A drive shaft comprises an axis, a drive groove, and a surface, wherein the drive groove forms a continuous channel along the surface and receives the first drive pin. In one embodiment, a first distribution wheel comprises a first face, a second face, a first inlet aperture, and a first outlet aperture. The first distribution wheel couples to the first piston cylinder and to the drive shaft at a first end of the drive shaft, and rotates axially with the drive shaft along the axis of the drive shaft. The first inlet aperture allows hydraulic fluid to pass through the first face and the second face and the first outlet aperture defines a groove on the second face.

In a stroke-limiter equipped integral power steering apparatus, a valve body of a spring-loaded-plunger-equipped limiter valve is configured to enable a position of the valve body relative to a housing to be adjusted in a longitudinal direction of the valve body via an intermediate sleeve.

The invention relates to an energy-efficient apparatus driven by compressed air and equipped with a dual piston function for tensioning, or clamping, or centering, or punching, or welding, or clinching, for use in body construction in the automotive industry. The apparatus is driven by a pressurized fluid, in particular by compressed air. It is shown how a significant amount of operating costs can be saved while, at the same time, conserving the environment and consuming a low amount of pressurized fluid, in particular compressed air. In addition, the pivoting angle of a toggle joint assembly and thus of an apparatus connected thereto, for example, a tensioning arm of a toggle tensioning apparatus, can be continuously adjusted in both directions while, at the same time, adjusting a sampling device using sensors, for example, microswitches, or inductive switches, or pneumatic switches, or limit switches.

A work vehicle includes an engine, an idling stop execution portion, a determination portion, a counting portion, and an idling stop time period adjustment portion. The engine can rotate in a first idling state and a second idling state in which the engine rotates at the number of rotations higher than a prescribed number of rotations. The idling stop execution portion performs an idling stop operation for stopping the engine. The determination portion determines whether or not stop has been made from the second idling state. The counting portion counts the number of times of stop of the engine from the second idling state. An idling stop time period adjustment portion makes a prescribed time period of the second idling state longer than a current time period, when the number of times of stop of the engine is equal to or greater than the prescribed number of times.

An apparatus can include a pressure vessel that defines an interior region that can contain a liquid and/or a gas. A piston is movably disposed within the interior region of the pressure vessel. A divider is fixedly disposed within the interior region of the pressure vessel and divides the interior region into a first interior region on a first side of the divider and a second interior region on a second, opposite side of the divider. The piston is movable between a first position in which fluid having a first pressure is disposed within the first interior region and the first interior region has a volume less than a volume of the second interior region, and a second position in which fluid having a second pressure is disposed within the second interior region and the second interior region has a volume less than a volume of the first interior region.

A servomechanism has a jet pipe mounted by a flexure pivot driven by an electromagnet to control the position of the jet pipe. A fixed seal tube surrounds the armature and keeps the coil isolated and dry. The flexure pivot has two parts that can move with respect to one another. The jet pipe can be fixed with respect to one part and movable with respect to the other such that when the electromagnet armature moves pivotal motion is imparted to the jet pipe. A multi-port jet receiver receives media from the jet pipe in different orifices dependent upon armature position. That in turn can extend or retract an actuator, such as a piston, depending upon which receiver orifice receives greater pressure. A feedback mechanism can link the actuator to the jet pipe to provide feedback input used to improve the accuracy of the device.

A radial thermal engine with an improved valve system is disclosed herein comprising intake and exhaust port valve assemblies fluidly connected to respective intake and exhaust ports contained within a cylinder head assembly. Each intake and each exhaust port valve assembly comprises at least one rotatable port cover having spaced apart openings which are periodically alignable to the intake and exhaust ports, respectively.

The invention relates to a method for the impregnation of a product consisting of fibrous material and formed from a continuous web (22), the method comprising at least one first step of cutting out a specific zone (24) of the continuous web (22) and at least one second step of applying an impregnation product to the specific zone (24), the first and second steps being carried out simultaneously or virtually simultaneously.

Valve control device includes a body with a longitudinal axis, a control member housed at least partially in the body in a bottom portion along the longitudinal axis, a piston movable along the longitudinal axis and housed in a portion of the body forming with the piston a control chamber of the piston, an element movable in rotation with respect to the longitudinal axis on a top portion of the body, and sealing means between the movable element and the control chamber in the area of the connection port and/or of the passage.

A fluid-working machine has a working chamber of cyclically varying volume, high and low pressure manifolds, and high and low pressure valves for regulating the flow of fluid between the working chamber and the high and low pressure manifolds respectively. A controller actively controls at least one said valve to determine the net displacement of working fluid of the working chamber on a cycle by cycle basis. At least one said valve is a variable timing valve and the controller causes the valve to open or close at a time determined taking into account one or more properties of the performance of the fluid working machine measured during an earlier cycle of working chamber volume.

A brake actuating unit for actuating a motor vehicle braking system of the “brake-by-wire” type having a brake booster. In order to provide a brake actuating unit for actuating a motor vehicle braking system of the “brake-by-wire” type, which on the one hand fulfills the statutory requirements care and which on the other hand is inexpensive to produce, it is proposed according to aspects of the invention, that the brake booster be provided as a travel-controlled brake booster, so that when not in the “brake-by-wire” operating mode the brake pedal is decoupled from feedback forces of the brake actuating unit, and the return force is simulated by the pedal travel simulator even when not in the “brake-by-wire” operating mode.

In a reciprocating piston compressor with delivery rate control, the electromagnetic actuating device (3) of the valve lifter (2) has a separate positioning drive (10) for adjusting the working stroke range of the magnetic actuator (5) used, whereby this can be chosen to be small and highly dynamic and only low power losses occur.

An assembly of valve sections includes an inlet section, an outlet section, a working section, and a working section. The working section is a conventional pressure compensated working section. The working section includes a directional control valve, a pressure compensator valve, and a pressure limiter valve. The valves are of integral construction, such that each is an essential part to complete the other. The pressure compensator valve includes a pressure compensator spool movable between an opened position and a closed position in response to a pressure differential across the spool. The pressure limiter valve includes a pressure limiter spool that moves to an open position to change the pressure differential and close the pressure compensator valve when a selected limit pressure is reached.

An arrangement for providing a throttle cross-section for a fluid flow. The throttle cross-section can be varied depending on a pressure difference present across the throttle cross-section. The arrangement is designed such that the polarity of the pressure difference, by which the throttle cross-section can be varied and/or changed. It is thereby possible to use the arrangement for fluid flows that alternate in the flow direction thereof.

A volume booster for a fluid flow control device comprises a supply path for supplying a fluid boost to facilitate actuation of an actuator in a first direction, and an exhaust path for enabling controlled exhaust to facilitate actuation of the actuator in a second direction. The supply path defines a supply resistance that is set by the geometry of a supply trim component. The exhaust path includes an exhaust resistance that is set by the geometry of an exhaust trim component. The supply and exhaust trim components are independently removable and replaceable with replacement components to customize the exhaust and supply resistances, and therefore, the exhaust and supply capacities for specific applications.

The invention relates to a welding wire feed system for feeding welding wire over a considerable distance from a remotely located wire storage spool to a welding gun through the use of straight lengths of angularly related conduit and intermediate low friction wire direction changing devices.

A welding process, such as a GMA welding process, employs a consumable electrode with the consumable electrode being oscillated back and forth over the surface of an object to which welding material is to be applied or across the gap between two pieces of metal to be welded together. At the ends of the swings of the consumable electrode an impact force is applied to the consumable electrode to interrupt its movement, thereby causing molten metal at the end of the consumable electrode from which the arc is struck to be impelled therefrom.

An electrical discharge machine with automatically replaceable electrodes. The machine includes an electrode holder with a clamp operable to alternately receive and release an electrode, an electrode cartridge containing a plurality of stacked electrodes and a shuttle movable toward and away from the electrode holder. When the shuttle is moved toward the electrode holder, it removes an electrode from the cartridge and moves it into alignment with the electrode holder.

A carbon exchanging system for a carbon-arc weather resistance testing apparatus having a carbon drive system including a reversible motor for automatically moving upper and lower arc producing carbons toward and away from each other along a vertical line for keeping the discharge current and voltage substantially constant. The carbon exchanging system has remotely operable upper and lower carbon chucks for holding the upper and lower carbons, a carbon replacing device having a remotely operable exchanging chuck and a drive for moving the exchanging chuck along a path of movement toward and away from the upper and lower carbon chucks when they are in position on the vertical line, a shifting device for shifting the carbon drive system and the carbon replacing means relative to each other for moving the upper and lower chucks and the exchanging chuck laterally relative to the vertical line, a carbon supply adjacent the path of movement of the exchanging chuck for holding replacement carbons and moving them into position opposite a position of the exchanging chuck along the path, and a moving device for moving the exchanging chuck and the carbon supply relative to each other in a direction toward and away from each other. The system can also include a control device for automatically controlling the operation thereof.

Graphite and/or carbon surfaces are coated with a titanium nitride coating by exposing the substrate to electric arc thermal spray process wherein titanium wire as the source of titanium and nitrogen is used as the propelling (atomizing) gas.

A geared motor actuator having a simplified mechanical structure for driving a closing part, such as a vehicle window, moved as far as at least one end position by an electric motor (MO) via a gear (G), preferably a worm gear. Shortly before the end position is reached, switch-off of the electric motor (MO) is performed in accordance with a control device (ST). The gear (G) is drive-connected to an output driver of the closing part without any damping means. The worm wheel (4) of the worm gear, being a solid, integral component that is preferably injection-molded from plastic, is preferably designed to include the output driver as part of the integral component, and provided with a drive pinion (4.1).

A method and a system for supplying power to a microcontroller with a single cell. One embodiment of the present invention discloses incorporation of a power supply pump circuit with the microcontroller and their dynamic interaction. The microcontroller sends its power requirements to the power supply pump circuit and in response, the power supply pump circuit controls the operating voltage with optimal efficiency. The dynamic update of power supply pump circuit results in an efficient use of the power supply pump circuit and thus results in a reduction of the number of dry cell batteries to only a single cell. Incorporation of the microcontroller and power supply pump circuit onto a single chip reduces the pin number requirements as well as the space required on the printed circuit board.

An information handling system (IHS) employs a power fault protection circuit to protect the IHS from overvoltages which may occur on an information line from a power adapter to the IHS. The system includes a processor coupled to the protection circuit. The circuit is operative in a first mode to decouple an information line from the IHS in response to a disable command and operative in a second mode to decouple the information line from the IHS when a voltage in the information line exceeds a predetermined threshold voltage.

A wafer surface inspection method and apparatus of high sensitivity, and free from performance degradation in terms of cleanliness, coordinate repeatability of foreign particles and the like. Gas for cooling is sprayed onto a laser irradiation position on the wafer surface to prevent an increase in temperature of the foreign particles and to suppress break-down of the foreign particles.

In general, this disclosure describes techniques for changing a sampling frequency of a digital signal. In particular, the techniques provide a more accurate way to determining a relative timing between a desired output sample and a corresponding input sample using a non-approximated integer representation of the relative timing. The relative timing between the desired output sample and corresponding input sample may be represented using a first component that identifies a latest input sample of the digital signal used to generate intermediate samples, a second component that identifies an intermediate sample, and a third component that identifies a timing difference between the desired output sample and the intermediate sample. Each of the components may be recursively updated using non-approximated integer values.

A shelf accessory for a dishwasher rack is provided, comprising a spine extending in parallel with a structural member of the rack. A plurality of loops extends perpendicularly from the spine, and the loops are spaced apart in relation to each other along the spine, and cooperate therewith to define a shelf member. A clip member is operably engaged between the shelf member and the structural member, and is configured to be capable of rotating about the structural member such that the shelf member correspondingly orbits about the structural member. The clip member further comprises at least one retention member operably engaged therewith. The at least one retention member is configured to cooperate with the rack so as to retain and support the shelf member in at least one of a plurality of angular positions with respect to and about the structural member. Associated apparatuses are also provided.

A power tool has an electric motor that includes a commutator, with which at least one commutator brush is acted upon with spring force via at least one commutator spring in the direction of a non-rotatable collector of the commutator. At least one auxiliary tool for adjusting the commutator spring is located on a component of the power tool.

A method and a system for supplying power to a microcontroller with a single cell. One embodiment of the present invention discloses incorporation of a power supply pump circuit with the microcontroller and their dynamic interaction. The microcontroller sends its power requirements to the power supply pump circuit and in response, the power supply pump circuit controls the operating voltage with optimal efficiency. The dynamic update of power supply pump circuit results in an efficient use of the power supply pump circuit and thus results in a reduction of the number of dry cell batteries to only a single cell. Incorporation of the microcontroller and power supply pump circuit onto a single chip reduces the pin number requirements as well as the space required on the printed circuit board.

Apparatuses, methods and systems for lighting fixture determining its power usage and monitoring its operational health are disclosed. One embodiment includes a method of a lighting fixture determining its power usage. The method includes sensing, by an ambient light sensor, an intensity of light emitted from the lighting fixture, and estimating power usage of the lighting fixture based on the sensed intensity of light.

A welding head is provided. The welding head includes a bracket and a plurality of blocks coupled to the bracket. Each of the plurality of blocks has a contact tip. The contact tips are adapted to receive an electrode. Further, at least one of the plurality of blocks is capable of variable positioning relative to the bracket.

A two wheeled, height adjustable cart for pulling farm implements and maintaining a stable height for the cart relative to the field includes a pair of spaced wheels to which main frame members are connected and extend upwardly therefrom. A work platform having a seat for an operator is slidably mounted on the main frame members and selectively movable between an elevated position and a lowermost position, and attached to the work platform is the farm implement which is raised and lowered concomitant with the movement of the work platform from the elevated position to the lowermost position. Foot pedals mounted on the work platform actuate the raising of the work platform to the elevated position and the lowering of the work platform to the lowermost position. In addition, position setting mechanisms mounted on the main frame members allows the operator to set the lowermost position to which the work platform will descend, and which determines the depth the farm implement will extend into the soil, and also allows the operator to raise the work platform and the attached farm implement when both are stationary, or when the cart is stationary for undergoing maintenance.

A device and method to facilitate wearing of jewelry items which have hoop and clasp closures, comprising: a base or clamp for stabilizing the device on a surface; a wire guide member protruding from the base and affixed securely thereto, the wire guide having hook at its opposite end for engaging a distal hoop or link on an unclasped jewelry item, thereby permitting a person to: a. engage one end of a jewelry object with a device, b. open a complementary jewelry clasp with one or both free hands, c. position a wrist or neck within the bight of the jewelry item, d. close the clasp upon the hoop link, and e. slidably remove the clasped jewelry item from the device.

A compressor includes a housing; a compressor liner positioned within the housing and at least partially defining a first cylinder with an inlet and an outlet; a piston positioned within the first cylinder and configured to compress air flowing into the first cylinder through the inlet; a cylinder head at least partially defining the first cylinder; and a sealing assembly for sealing an interface between the compressor liner and the cylinder head. The sealing assembly includes a ring seal at an interface between the cylinder head and the compressor liner; a vent port on an opposite side of the ring seal from the first cylinder; and a vent tube extending between the vent port and the inlet such that air leaking through the ring seal from the first cylinder flows through the vent port, through the vent tube, and into the inlet.

Apparatus for drainage by well points, including a piston pump and a drive motor coupled to the piston pump by means of a transmission and provided with a drive shaft, which transmission is received in a housing and includes at least one crankshaft and a drive rod coupled thereto, the drive rod is coupled by means of a cross-head to a piston rod of the piston pump and the housing forms an oil sump and the transmission further includes an assembly of a worm and a worm wheel co-acting therewith and mounted on the crankshaft and the worm is provided on a worm shaft extending transversely relative to the crankshaft and vertically in operating mode of the apparatus for drainage by well points.

A fluid actuator includes a housing having a fluid chamber providing a first friction surface. An actuating member is arranged in the fluid chamber and has a second friction surface slideably engaging the first friction surface. The actuating member is configured to slide within the chamber between first and second positions. An insert is constructed from a first thermoplastic material and provides one of the first and second friction surfaces. A body structurally supports the insert and provides one of the housing or actuating member. The body is constructed from a second thermoplastic material molded about the insert and including short reinforcing fibers.

The present invention provides a variable displacement swash plate type compressor that reduces wear of cylinder bores and the amount of blow-by gas. Each piston of the compressor has a piston main body, which has a distal portion located at an end corresponding to the compression chamber. A tapering portion and an arcuate portion are formed in the distal portion. The arcuate portion is continuous with an end of the tapering portion that is closer to the compression chamber. The tapering portion and the arcuate portion each have a diameter that increases toward the skirt. The tapering portion has a tapering angle that is in a range from 0.45 degrees to 1.5 degrees. The distance between the distal end of the piston main body and a starting point of the tapering portion on an end closer to the skirt is set in a range from 1.5 mm to 5.0 mm.

The invention relates to a combination cylinder, including a service brake cylinder as an active service brake with at least one service brake piston actuated by a pressure medium, the piston actuating a brake mechanism via a service brake piston rod, and further including a spring-loaded brake cylinder as a passive parking brake with a spring-loaded brake piston actuated by a pressure medium against the action of at least one pre-loaded spring, wherein the spring-loaded brake piston in the event of the parking brake is actuated transmits the power of the at least one pre-loaded spring by means of a power-transmitting transmission to the service brake piston rod. According to the invention, the transmission is designed such that the movements of the spring-loaded brake piston and the service brake piston rod are coaxial and the power transmission increases with increasing stroke of the spring-loaded brake piston.

The present invention relates to a position sensor and limit switch apparatus for an actuator. The actuator has a cylinder and a piston with at least one magnetized portion reciprocatingly disposed within the cylinder. The apparatus includes an elongate housing aligned parallel with the cylinder. A magnetostrictive linear displacement transducer is disposed within the housing for sensing the position of the at least one magnetized portion. The apparatus includes a switch means responsive to the transducer for operatively interrupting actuation of the piston upon the at least one magnetized portion reaching a limit position.

Disclosed is a wobble plate type variable displacement compressor that uses a constant velocity universal joint mechanism, which comprises an inner ring and an outer ring, balls that are held between guide grooves of the inner ring and the outer ring to transmit power, wherein a wobble plate is connected and fixed to the outer ring. In the compressor, the wobble plate is provided with a cylindrical part which extends in the axial direction of a swash plate, and in the relative rotation structure between the swash plate, and the wobble plate and the outer ring, the swash plate is supported to be able to relatively rotate only in relation to the wobble plate via a bearing interposed at least between the cylindrical part and the inner diameter portion of the swash plate, without being supported to be able to rotate relative to the outer ring. With this wobble plate type variable displacement compressor using the specified constant velocity universal joint mechanism, the relative rotation structure between the wobble plate and the outer ring, and the swash plate, can be improved, workability and productivity can be improved, and the cost and weight can be reduced.

A hydraulic actuator system including an actuator and a valve assembly configured for bi-directional regeneration. The actuator may include a hollow body and a rod disposed within and extending outwardly from the hollow body. The rod may include a first chamber within the rod and a piston disposed at one end of the rod, defining a second chamber and a third chamber within the hollow body. A valve assembly may be in fluid communication with a first conduit, a second conduit, the first chamber, the second chamber, and the third chamber, wherein the valve assembly is configured to selectively couple one of the first conduit and the second conduit to one or more of the first port, the second port, and the third port, wherein one of the first conduit and the second conduit is configured as a pressure source.

To improve productivity and increase seizing resistance and abrasion resistance of a sliding surface of a tilt adjustment cylinder, a plurality of pistons are arranged cirumferentially in a cylinder block configured to rotate with a rotating shaft. Tip end portions of the pistons slide along the swash plate, and the pistons reciprocate. The swash plate is supported to tilt with respect to the rotating shaft. Further, a tilt adjustment driving portion is included. The tilt adjustment driving portion includes tilt adjustment large- and small-diameter cylinder chambers and tilt adjustment large- and small-diameter pistons configured to slide in the cylinder chambers to change the tilt angle of the swash plate. A sliding surface of the inner peripheral surface of each of the cylinder chambers includes a quenched portion formed by quenching using laser light, the sliding surface being a surface on which the tilt adjustment piston slides.

A variable displacement fluid working machine includes an inward ring and an outward ring, one of the inward ring and the outward ring including a rotatable ring cam coupled to a drive shaft, the other including a plurality of radially extending piston cylinders circumferentially spaced around the respective ring. The outward ring has first and second axially spaced structural members and a plurality of demountable blocks demountably retainable therebetween, the demountable blocks having either piston cylinders or ring cam segments. The demountable blocks are removable radially to facilitate maintenance and repair and to facilitate radial access to the inward ring.

High pressure pump systems with reduced pressure ripple for use with waterjet systems and other systems are described herein. A pump system configured in accordance with a particular embodiment includes four reciprocating members operably coupled to a crankshaft at 90 degree phase angles. The reciprocating members can include plungers operably disposed in corresponding cylinders and configured to compress fluid (e.g., water) in the cylinders to pressures suitable for waterjet processing, such as pressures exceeding 30,000 psi.

A hydraulic cylinder includes a cylinder assembly having a cylinder, defining an inner hydraulic chamber and being for reciprocating receipt of a piston and piston rod therein; a piston rod extending from the inner hydraulic chamber exteriorly of the cylinder; and a piston head assembly connected with the piston rod and disposed for reciprocation within the cylinder assembly. The piston head assembly includes a piston head and a valve assembly including a passageway defined in the piston head and a valve member having an outer surface and being sized and configured for reciprocation in the passageway between extended and retracted positions therein, the valve member defining at least one flat defined along the outer surface and at least one transition surface between the outer surface and the flat, the transition surface forming an angle with the flat of between about 40 and 50 degrees.

The invention relates to a rotary machine with pistons (22) and a turret (25), including: —a frame (2), through which a shaft (1) extends, having a geometrical axis x-x' and mounted in a stationary manner relative to the frame (2); —a thrust plate (9) rotatably mounted on the shaft (1); —an oscillating plate (15) bearing on the thrust plate (9); —a torsion bar (18), a first end of which is pivotably connected to the frame (2) and a second end of which is pivotably connected to the oscillating plate (15); —a spherical female bushing (14) rigidly connected to the oscillating plate (15) and pivotably connected around a spherical male knuckle centered on the shaft (1), the knuckle including a spherical male bushing (10) rotatably mounted relative to the shaft (1), characterized in that the rotary machine includes a means for rotating the spherical male bushing (10) about the geometric axis x-x'.

The present disclosure relates to a piston-cylinder unit with a device for determining position, the device comprising at least one exciter that is indirectly or directly electrically connected with the cylinder jacket and the cylinder piston of the piston-cylinder unit, and that excites the electrical oscillating circuit formed by the piston-cylinder unit and the contact lines to oscillate at its resonant frequency, it being possible to measure an electrical signal characterizing the resonant frequency on the piston-cylinder unit. The invention also relates to a construction machine or piece of hoisting equipment with such a piston-cylinder unit.

A rodless power cylinder includes a cylinder body, a piston assembly adapted to reciprocate in the cylinder body, a magnet mounted at each of the two ends of the piston assembly, a valve mounted at each of the two ends of the cylinder body for guiding a flow of air or fluid in and out of the cylinder body to cause the piston assembly to reciprocate, a magnetic sensor mounted in a sensor mounting groove at each of the two valves for sensing the position of the respective magnet, a movable member mounted around the cylinder body and coupled to the piston assembly by a magnetic force for synchronous reciprocating motion.