Abstract: A plurality of detection valves (12 and 13) are provided to a housing (1), and at least one air passage (14 and 15), which communicatively connects the detection valves (12 and 13) to each other in series, are provided to the housing (1). One or some of the detection valves (12 and 13) are each configured as a throttle detection valve (13) including a throttle passage (56a).

Abstract: A method monitors the state of a device having a first drive cylinder for receiving hydraulic fluid and a first drive piston which is movably arranged in the first drive cylinder. The method determines a speed of the first drive piston, establishes a difference between the determined speed of the first drive piston and an expected speed of the first drive piston, and determines a faulty state as a function of the difference established between the determined speed of the first drive piston and the expected speed of the first drive piston.

Abstract: A safety valve which has two fluidically interconnected safety valves, each of which has a 4/2-way valve function. Each safety valve has a first connecting port and a second connecting port, which are connected to each other in such a way that a fluid flow through the two safety valves, controlled by means of a control valve, to a fluid-actuated drive is prevented if the two safety valves simultaneously adopt a first switching position and such a fluid flow is possible if both valves simultaneously have a second switching state. One safety aspect results from the fact that the above-mentioned fluid flow is also prevented if the two safety valves adopt different switching states.

Abstract: A pump including one or more pumping chambers, one or more drive mechanisms for driving the one or more pumping chambers and a logic arrangement. The first pumping chamber of the one or more pumping chambers has a first inlet check valve, a first outlet check valve and a first temperature sensor. The logic arrangement is configured to identify a leak by applying logic to at least resistance-data indicative of a resistance of the first pumping chamber to the driving and temperature-data at least based on output from the first temperature sensor.

Abstract: An anomaly detection method and system for a process instrument, and a storage medium are disclosed. The method includes that: a programmable logic controller (PLC) receives measurement data of a process instrument, the measurement data being periodically stored into a historical database so that a service providing system can perform reading and evaluation. At least one virtual function module is integrated on the PLC, a mapping relation is formed between at least one input channel of each virtual function module and output of at least one anomaly diagnosis algorithm disposed on the service providing system, and each anomaly diagnosis algorithm is used for diagnosing whether an anomaly exists in the process instrument. When an anomaly indication outputted by the service providing system is received via an input channel of the virtual function module, the PLC determines that an anomaly exists in the corresponding process instrument.

Abstract: An aircraft landing gear assembly includes a bi-stable, split line tube biased to assume a tubular condition to serve in place of a lock link or side stay and a flexible vessel actuator configured to radially enlarge the tube at a region for folding.

Abstract: A handle assembly and a stapler including the same are provided. The handle assembly includes: an indicator; a first handle and a second handle; a slot and a slider, provided in the first handle, the slider can be actuated by the indicator to move from a first section to a second section of the slot; when the slider in in the first section, the second handle cannot be actuated by the first handle and is in an insurance position; when the slider is in the second section of the slider, and the second handle can be actuated by the first handle to move towards a firing position. Therefore, no matter whether the stapler is ready to be fired or not, the first handle can be pressed by the doctor. However, when the stapler is not ready to be fired, the second handle won't be actuated to fire the stapler.

Abstract: A driving tool capable of avoiding blank shot after a predetermined time has elapsed when performing a bump firing and capable of smoothly performing the bump firing is provided. The driving tool includes: an accumulator chamber which accumulates compressed air; a nose section provided on a housing; a cylinder; a trigger; and a push lever provided in the nose section, and when the trigger and the push lever are operated, the compressed air is supplied into the cylinder. The driving tool further includes: a delay valve which prevents the compressed air from being supplied into the cylinder when the push lever is not operated within a predetermined time after the trigger is operated: and a switching valve which supplies the compressed air of the accumulator chamber to the delay valve when the trigger is operated, and discharges the compressed air supplied to the delay valve to an outside of the housing when the push lever is operated within the predetermined time.

Abstract: A proportional control fluid actuator that is used as a positioning device in applications such as a hydraulic directional control valve. The activating device has a cylinder body attachable to a valve body and has a bore carrying a piston that is coaxially secured to an end of a valve spool. The device is provided with spaced openings in the cylinder body that communicate with the bore therein to introduce fluid to act on opposite sides of the piston. Factory pre-compressed spring means are provided for normally urging the piston and spool to a center position. Since the areas of the fluid pressure applied on both sides of the piston are different (due to a spool on one side of the piston), two pre-compressed springs are used to compensate the area difference to achieve a proportional movement of the spool.

Abstract: In a diagnostic method for a positioning device of a process plant, such as a chemical plant, a food processing plant or the like, which includes an actuator (e.g. pneumatic or electric actuator) with a drive shaft and a positioning armature, such as an actuator valve, with a positioning shaft, the drive shaft and the positioning shaft being connected to each other in a rotationally fixed manner (e.g. by a detachable coupling interface and/or a positive-locking torque coupling, such as a claw coupling), wherein a first measurement signal is detected during a movement of the drive shaft, and the first measurement signal or a derivative of the first measurement signal is evaluated with respect to a step-like change in order to detect a rotational backlash.

Abstract: An apparatus is disclosed. The apparatus includes an operating table column head assembly, a patient support surface assembly that is movable relative to the operating table column head assembly, and an actuating cylinder configured to move the patient support surface assembly relative to the operating table column head assembly, the actuating cylinder including a piston rod. A first gear rack is attached to the operating table column head assembly and a second gear rack is attached to the patient support surface assembly. A gear assembly is disposed on the piston rod of the actuating cylinder. The gear assembly engages with the first gear rack and the second gear rack. The first gear rack and the second gear rack move in substantially opposite directions relative to the gear assembly, when the actuating cylinder is actuated.

Abstract: A system and method for remotely locating a communication error support for hydraulic supports. The system includes a control panel, a support controller, a data converter, and two support drivers of the same type. Each support driver has two bus interfaces. The control panel transmits a control command to the data converter in a form of a WiFi signal. The data converter converts the WiFi signal into a message signal and transmits the message signal to the support controller. The support controller transmits the control command to the two support drivers, respectively. The support drivers transmit the command through CANH twisted pairs and CANL twisted pairs. When a bus for transmitting the command of a certain node has an error, the support controller calculates the fault node according to a formula n = p ? t 8 ? m , and feeds back the fault node onto the control panel.

Abstract: A rod detensioning unit including a gripping unit removal device that engages a gripping unit on a rod, a chair frame configured to engage a rod, a rod tensioning unit that applies tension to an external portion of the rod to remove load from the gripping unit, a load cell unit that measures a tension level applied to the rod by the tensioning unit, a plate gripping unit that engages the rod and secures the chair frame, rod tensioning unit, load cell and plate gripping unit to the rod, a drive unit that engages the gripping unit removal device, and an extension unit affixed to the external portion of the rod when the original external rod length is too short to accommodate the de-tensioning unit.

Abstract: Systems and methods for controlling wellsite equipment, including a cementing unit comprising a plurality of sensors operable to generate information related to operational status of the cementing unit and a controller comprising a processor and a memory including computer program code. Communication is established between the cementing unit and the controller. The controller is operable to operate the cementing unit to automatically perform: a pressure calibration of the cementing unit, a pressure test of the cementing unit, an over pressure shut-down test of the cementing unit, a low rate pumping test of the cementing unit, a hydraulic horsepower test of the cementing unit, and/or a mixing test of the cementing unit.

Abstract: A system includes a pump. The pump includes a piston configured to axially reciprocate within a body. The axial movement of the piston activates a first chamber valve and a second chamber valve. The system also includes a main valve configured to direct a flow to the pump to facilitate the axial movement which then transfers a fluid from a reservoir to a spray applicator. The system includes a runaway valve system fluidly coupled to the main valve and configured to detect a runaway state of the pump. The runaway valve system is configured to direct the main valve to stop operation of the pump in response to detection of the runaway state.

Abstract: A method is provided for detecting a reciprocal position between a cylinder and a piston of a piston-cylinder unit of a vehicle. The method includes measuring, by means of an optical sensor, a value of an indicative parameter of a color of a reference mark positioned on a portion of the piston. The method also includes comparing the measured value with at least a predetermined threshold value thereof different to a minimum detected threshold of the indicative parameter by the optical sensor; and emitting an alarm signal perceptible by a driver of a vehicle if the measured value is comprised between the threshold value and the minimum value.

Abstract: A pressure sensing apparatus with multiple, isolated pressure sensors provided therein. The apparatus includes a base cover portion having multiple sections and each section defines an opening. A sensor is positioned in each base cover portion and a portion of each sensor is exposed to the respective opening. A flanged base is coupled to the base cover portion to define multiple separate chambers and a housing is provided around the base cover portion and base and the housing has multiple conduits in fluid connection with respective cover openings.

Abstract: Disclosed is a control system for a hydraulic work machine, comprising a plurality of hydraulic work circuits for supplying actuators and/or drive units of movable machine parts with hydraulic fluid, and an emergency stop circuit for the work circuits for avoiding danger caused by the machine parts. According to this disclosure, the emergency stop circuit comprises a single safety valve which is connected in parallel to the work circuits via at least one branch line each at the inlet and to a pressure relief point at the outlet.

Abstract: A laser piston position sensor for determining the position of a piston within an accumulator, the laser piston position sensor configured to attach to an end of the accumulator, and the accumulator having an aperture in the end thereof exposing the piston within the accumulator to the laser piston position sensor. The laser piston position sensor including a sensor housing enclosing a cavity containing a low pressure gas, and defining an opening from the cavity toward the accumulator, a laser sensor positioned within the cavity for emitting a laser toward the piston of the accumulator via the opening in the sensor housing and the aperture in the accumulator, and a transparent lens positioned between the laser sensor and the accumulator to allow passage of the laser from the laser sensor to the piston, and to separate gases in the accumulator from gases in the cavity of the sensor housing.

Abstract: A method of inserting a data structure into a component using a 3D printer is provided. The method includes providing the data structure having at least one structural parameter associated with the component, converting the data structure into indicia representative of the data structure, and manufacturing the component containing the indicia.

Abstract: A sensor (S) is provided for determining the stroke of the piston rod (6) of a fluid cylinder, particularly a hydraulic or pneumatic cylinder. The sensor includes a lighting unit for illuminating a code applied on the surface of the piston rod and differing from said surface by color, a first camera unit with a first lens system for recording a first image of the illuminated code in a first scanning window, an evaluation unit for evaluating output signals of the first camera unit, and an interface for issuing the evaluated output signals as information regarding the position of the piston rod. Additionally, a second redundant camera unit is provided with a second lens system, which serves for recording a second image of the illuminated code in a second scanning window.

Abstract: A method for adjusting a barometric cell may include coupling the barometric cell to a control device via an actuating rod. The actuating rod may be movably mounted on a charging device in any desired position. The method may include applying a freely selectable pressure to the barometric cell so as to bring the actuating rod into contact with a stop, adjusting the barometric cell until a sensor registers a predefined value, and fixing the barometric cell on the charging device.

Abstract: A braking device, for a motor vehicle brake system. The braking device has at least one movable activation element, at least one device for monitoring the position and movement of at least one activation element, and at least one compressible, electrically conductive device spring which is elastically prestressed between two abutments, wherein at least one of the abutments is of movable design, and the movement of the abutment is coupled at least partially to a movement of at least one activation element. The device spring is provided for moving at least one of the abutments into its unactivated release position. The invention proposes that the device spring be assigned a sensing function for monitoring the position and movement of at least one activation element. A degree of compression of the device spring can be sensed, and the device spring is arranged in an electrically insulated fashion between the two abutments.

Abstract: A device for monitoring the position and movement of a brake pedal for motor vehicles, including a power assist brake actuating unit. The brake actuating unit having a master cylinder fastened to the brake power assist unit, a housing and at least one piston displaceable in a linear manner in the master cylinder, and a position indicator for monitoring the position of the brake pedal. The position indicator transmits signals to a sensor element connected to an electronic control unit. The position indicator is provided on a support coupled to the movement of the control valve housing or to the movable wall that is supported by the control valve housing. The support is guided in a housing of a sensor element, and the housing of the sensor element penetrates in a vacuum-tight manner the power assist unit housing and the housing of the master cylinder having a first housing section.

Abstract: An actuator including a housing and a force sensing mechanism positioned within an interior of the housing and in operable communication with the actuator, the force sensing mechanism capable of measuring the various forces exerted by or on the actuator without losing any of the energy being transmitted by the actuator. A high precision position sensing mechanism can also be included with the actuator.

Abstract: The invention provides a method and a system for moving an element, e.g. a rudder of a ship or a wheel of a vehicle. The element is moved by a hydraulic fluid. According to the invention, an operator indicates a desired movement, and in accordance with the desired movement, at fluid is provided from at least three fluid providers each providing a share of the fluid in parallel streams and only considering the desired movement not the shares provided by the other fluid providers. The invention allows continuation of a steering task even if one fluid provider is disabled, and the invention allows the continuation even without having to notice that one provider is disabled. Accordingly, the invention provides an improvement and simplification relative to the known hydraulic steering systems.

Abstract: A sensor coupler adapted to operatively connect a sensor to a piston-cylinder assembly. The sensor coupler includes a first end member and a second end member. The first end member is disposed on a port of the piston-cylinder assembly, in communication with the sensor, and the second end member is disposed in a cylinder chamber of the piston-cylinder assembly. Further, one or more cables are extending between the first end member and the second end member. The one or more cables are configured to transmit signals indicative of a position of a piston in the piston-cylinder assembly to the sensor. The sensor coupler further includes a biasing member to connect the first end member and the second end member.

Abstract: Method of indicating the position of a hydraulically actuated armature, comprising an adjust cylinder for actuating the armature, connected by at least one pressure medium line to an adjustment valve through which the pressure medium line can be switched between pressure-causing forward flow and pressure-less backward flow, wherein the flow through the pressure medium line is converted into a number of electric pulses and the number of pulses reflecting the flow is processed in a program in an indicator unit such that the number of pulses occurring in a predetermined adjustment travel when the flow in the pressure medium line is pressure-less is calculated as being the same adjustment travel as when the pressure medium line is switched to be the pressure line.

Abstract: A failure detecting device of a fault detection system includes a detection time calculator, which calculates a stroke time T3 required for a piston to travel between one end and another end of an actuator based on detection signals from a first sensor and a second sensor, a statistical processor that performs a predetermined statistical calculation with respect to the stroke time T3, and a fault response detector, which detects whether or not a fault of the actuator has occurred based on a processing result of the statistical processor.

Abstract: A linear actuator assembly (30) having an inner sleeve (100) which moves in a first direction or in an opposite second direction relative to a fixed outer sleeve (90) between a fully extended position and a fully retracted position. The linear actuator assembly (30) also has an emitter (180) and a sensor (184) positioned near the emitter (180) that detect changes in an emitted signal resulting from the movement of the inner sleeve (100) relative to the outer sleeve (90) along a longitudinal axis and a controller (101) electrically coupled to the sensor (184) to determine the axial position of the inner sleeve (100) relative to the outer sleeve (90) along the longitudinal axis.

Abstract: In an actuating drive or method for capturing a position of a final control element to be positioned by a drive member of the actuating drive, the final control element is pushed from an initial position to a target position by a spring body acting on the drive member. A first reference position is spatially configured in a vicinity of or at the spring body. A second reference position moving relative to the first reference position during positioning movement of the drive member is spatially configured adjacent a first outer surface of the spring body. A distance between the first reference position and the second reference position is captured.

Abstract: A control system for extending and retracting a ram of a hydraulic coupler for coupling an attachment to an arm of an excavator or back hoe, said control system being adapted to provide an audible and/or visual alert to an operator to indicate a leak of fluid or loss of fluid pressure from said ram and/or from a hydraulic circuit supplying said fluid to the ram. Preferably the control system further comprises a flow sensor for sensing the flow of fluid in a feed line for supplying pressurized fluid to the ram and/or a pressure sensor for sensing the pressure of fluid in said feed line, said control system including at least one indication device for providing said audible and/or visual alert to an operator to indicate a leak of fluid or loss of fluid pressure in response to, or as a function of, the output of the flow sensor and/or the pressure sensor.

Abstract: A pneumatic drive and a method for acquiring the power of a pneumatic drive are specified. A piston is movably disposed in a working space and coupled to a path transducer. A pressure sensor is provided for acquiring an internal pressure of the working space. An evaluation unit of the pneumatic drive is adapted to process the value of a path distance of a movement of the piston acquired by the path transducer as well as a variation of the internal pressure in the working space acquired by the pressure sensor. The variation of the internal pressure is associated with the movement of the piston in the working space. Based on these values, a power of the pneumatic drive can be determined.

Abstract: A cylinder includes a piston moving in a cylinder housing fastened to a cylinder rod and rotatable about a cylinder longitudinal axis, and a position sensor comprising a sensor magnet and a sensor element, which interacts with the sensor magnet and which is configured to detect a cylinder rod position relative to the cylinder housing. The sensor magnet is fastened on the cylinder rod rotatably with respect to the cylinder rod and is guided non-rotatably with respect to the cylinder housing.

Abstract: An actuator arrangement for a motor vehicle drivetrain, in particular for a dual-clutch arrangement. A first fluid cylinder is connected via a first fluid connection to a fluid supply device. A second fluid cylinder is connected via a second fluid connection to the fluid supply device. A pressure measuring arrangement has a single pressure sensor which is connected by means of a connecting arrangement to the first fluid connection and to the second fluid connection.

Abstract: An actuator displacement measuring system in an electro-hydraulic system for a construction machine is disclosed, which can detect an actuator displacement using the characteristics of an electro-hydraulic system. The actuator displacement measuring system includes controlling driving of an electric motor, determining whether the electric motor is driven, determining whether a set pressure value of a relief valve is larger than or equal to a measured pressure value of the hydraulic system if a displacement value of an actuator that is always detected deviates from a zero value of a reference position, setting the actuator displacement value to a previous value if a pressure value of the hydraulic system is larger than or equal to a pressure value of a relief valve and calculating the actuator displacement value using a rotating speed of the electric motor.

Abstract: A fluid pressure cylinder and a clamp device that, when an output member arrives at a prescribed position such as, in particular, an advance limit position or a retraction limit position, are capable of detecting the position of the output member on the basis of change of air pressure as, due to an opening/closing valve mechanism, the communication state of an air passage within the clamp main body is changed over together with the operation of the output member.

Abstract: Pressure piston actuators and systems for control of wastegate in a turbocharger pressure that include the pressure piston actuators are disclosed. The pressure piston actuator includes a housing defining a chamber and a pathway leading to the chamber, a piston disposed within the chamber, a rod connected to the piston by a ball-and-socket joint, and a spring disposed in the chamber to bias the piston, and hence the rod, into a retracted position. Then, when fluid is introduced into the chamber, the fluid applies pressure to the piston. Once the pressure overcomes the bias of the spring, the piston, and hence the rod, moves into an extended position. For the system, the pressure piston actuator has the connector on the end of the rod opposite the ball-and-socket joint connected to the valve portion of a wastegate of a turbocharger.

Abstract: A hydraulic motor 10 of the invention includes a detected unit 52 formed on an outer circumferential surface of a cylinder block 14 and a rotation sensor 50arranged opposed to the detected unit 52 for detecting the detected unit 52. The rotation sensor 50 is provided on a position corresponding to a position between a deepest portion 41 of a cylinder hole 29 and a rear end face 28 of the cylinder block in an axial direction of the cylinder block. A fan driving device 60 is provided with the hydraulic motor 10, a bracket 61 to which the hydraulic motor is attached in a state in which a tip end of the rotational shaft 13 is arranged on a surface side thereof through a through-hole 64 and a fan 62 attached to the rotational shaft 13 and is driven by the hydraulic motor.

Abstract: A reciprocating pump assembly includes a pump housing that houses a crankshaft. Pistons are mechanically connected to the crankshaft for pumping fluid through cylinders. Each cylinder has a fluid inlet and a fluid outlet. The pump also has a monitoring housing connected to the reciprocating pump. Within the monitoring housing is a computer with memory. Pressure sensor assemblies sense a pressure value of a fluid within the pump, and are in electrical communication with the memory. An accelerometer positioned on the pump measures vibrations of the pump and is also in electrical communication with the memory for storage of sensed vibrations or displacements during operations. A proximity sensor in electrical communication with the memory is located within the pump housing to determine the rotational velocity of the crankshaft.

Abstract: The present invention relates to a piston-cylinder unit with a piston with adjoining piston rod, which is movably mounted in a cylinder, wherein the piston and the piston rod have a cavity into which at least one rod protrudes, by means of which an electrically conductive connection can be made directly or indirectly.

Abstract: The invention provides a motor-driven movement system for moving a movable element, the system comprising at least two actuators, each provided with means connecting it to the movable element and each dimensioned to be capable, on its own, of driving the movable element, a central control unit being connected to the two actuators in order to be capable of sending a position setpoint (Pos1, Pos2) to one or other of the actuators. According to the invention, the system further comprises control means for simultaneously controlling both actuators in terms of force in response to the position setpoint sent to one of the actuators. The invention also provides a method of driving such a system and a method of testing such a system.

Abstract: A bidirectional hydraulic system for operating table is disclosed, which has a switch valve connecting a bidirectional hydraulic pumping device with movable units of an operating table. The switch valve is driven by a motor, and has a valve block defining at least three outbound valve positions on the valve block's top surface, which is parallel to the inside bottom of the base, which the valve block is attached to, and thereof for controlling oil inlet and oil outlet. The switch valve switches among the outbound valve positions for respectively forming oil passages between the bidirectional hydraulic pumping device and hydraulic cylinders of the movable units.

Abstract: A system and method for controlling the movement of an implement of an earthmoving machine. The system includes a hydraulic actuator adapted to move the implement. A variable displacement pump is coupled to the actuator for delivering a pressurized fluid to and receiving pressurized fluid from chambers within the actuator. A sensor generates an output based on the position of the actuator's piston or piston rod, and a controller controls the displacement of the variable displacement pump in response to the output of the sensor by executing an algorithm to reduce the flow rate of the fluid to and from the actuator's chambers and thereby reduce the velocity of the piston as it approaches an end of a piston stroke thereof and prevent the piston from impacting the actuator at the end of the piston stroke.

Abstract: An adjusting element with a closed first end, a cylinder, a piston displaceably arranged in the cylinder that divides the cylinder into a first work space remote of the first end and a second work space in proximity to the first end, and a piston rod which is arranged at one side of the piston and which projects through the first work space and is guided out of the cylinder concentric to or center longitudinal axis of the cylinder at a second end opposite from the first end so as to be sealed by a guiding and sealing device. The adjusting element has a device for detecting the piston rod position and/or the extended length of the adjusting element. The device for detecting the piston rod position includes a microswitch arranged at the cylinder and at least one switching element cooperating with the microswitch.

Abstract: Configurations are provided for vehicular robots or other vehicles to provide shifting of their centers of gravity for enhanced obstacle navigation. Various head and neck morphologies are provided to allow positioning for various poses such as a stowed pose, observation poses, and inspection poses. Neck extension and actuator module designs are provided to implement various head and neck morphologies. Robot control network circuitry is also provided.

Abstract: Provided is a displacement detection device for a variable displacement compressor which has a configuration such that the displacement detection device can estimate the displacement with little effect from external disturbances, and can be used with pistons that do not require a high degree of machining precision, thus allowing for a greater degree of freedom in the shape of the surface to be detected. Also provided is a variable displacement compressor provided with the displacement detection device.

Abstract: A method is disclosed for detecting the drive type of an actuator, e.g., a pneumatic actuator, having a positioner for operating a final control element in a process engineering plant. The actuator is connected to the positioner by a mounting set, the positioner comprising an electronic control unit, which uses a microcontroller to receive one or more input signals, and to output actuating signals to control the flow of gas to or from the chambers of a single-acting or double-acting pneumatic drive. The position feedback sensors are equipped with a rotational measuring system. During commissioning of the actuator, the relationship between the drive volumes and the position signal is found and compared with transfer characteristics of known drive types. Where there is a match between the transfer characteristic defined by the value pairs of the given actuator and one of the transfer characteristics of the known drive types, the identified drive type is assigned to the given actuator.

Abstract: A device for detecting the absolute position of a cylinder rod is provided. A cylinder assembly has a cylinder body with a gland member positioned thereof. The gland member has a rod opening extending therethrough. An adjustable sensor is mounted on the gland member, the adjustable sensor being operable to read one or more detectable features of the cylinder rod. The adjustable sensor can be incrementally adjusted relative to the cylinder rod to optimize the gap provided between the adjustable sensor and the cylinder rod, allowing the sensor to detect the motion and absolute position of the cylinder rod. The detectable features may be three tracks of data including first timing data and position data.

Abstract: A motor control system includes a piston chamber and a piston assembly disposed within the piston chamber to move therein between first and second positions. A magnet is coupled to the piston assembly to move therewith and a sensor is axially mounted with respect to the piston assembly to generate a continuous output signal corresponding to a position of the magnet relative to the sensor. The motor control system also includes a controller for processing the output signal from the sensor to monitor continuously the position of the piston assembly within the piston chamber and for actuating the piston assembly to move in an upstroke toward the first position and in a downstroke toward the second position.