Abstract: A system and method for evaluating optical proximity corrected (OPC) designs is provided. The system includes an AFM measurement system for performing measurements relating to a segment of a feature pattern corresponding to a predetermined OPC mask feature. The measurement system is configured to determine a first image for the segment of the printed feature based upon the measurements. The measurement system compares the first image with another image corresponding to different OPC design to evaluate performance characteristics of the respective OPC designs.

Abstract: A method for determining a condition of a cylinder in an internal combustion engine having a plurality of cylinders. The method includes the steps of reducing an amount of power being generated by a first cylinder, increasing an amount of power being generated by each of the remaining cylinders, monitoring a condition of the engine, and determining the condition of the first cylinder in response to the monitored condition of the engine.

Abstract: A method and apparatus for determining the balanced condition of an engine having a balancer is provided. An engine balancer tester includes a sensor coupled to the engine. The engine generates first- and second-order vibrations that have vibration levels and the sensor generates a signal corresponding to the vibrations. A meter coupled to the sensor receives the signal and calculates a ratio between the vibration level of the first-order vibrations and the vibration level of the second-order vibrations. A comparator compares the ratio to a predetermined value to assess the balanced condition of the engine.

Abstract: A tire testing machine (10) comprising a movable simulated road surface (14), an axle (16) including a bearing surface (22) around which a tire/wheel assembly (T) can rotate; and a frame (18) which supports the axle (16) in a non-rotatable but vertically floatable manner relative to the simulated road surface (14) whereby the tire/wheel assembly (T) can be loaded in rolling engagement against the simulated road surface (14). The frame (18) comprises tie members (26) which extend from the axle (16) to a stationary support (28) in a geometrically sturdy (e.g., triangular) arrangement and non-damping piston members (30) which are interposed between the tie members (26) and the stationary support (28). The geometrically sturdy arrangement of the tie members (26) can be an isosceles triangular arrangement and the simulated road surface (14) can comprise the outer circumferential surface of a road wheel (20).

Abstract: The invention relates to a method for assessing the effect of yarn defects on textile fabrics, which are to be produced from a given yarn, by simulating an image of the fabric. So that assessment of simulated textile fabrics may be carried out with greater reliability and more easily, a first image (51) of the fabric is generated by simulation based on parameters or measured signals of the given yarn. A second image (52) of the fabric is generated by simulation based on parameters of a reference yarn and finally the first image is compared with the second image.

Abstract: The output characteristics of the sensing device or the control quantity of the sensing element can be adjusted by extracting an adjusting terminal in addition to a power source terminal, a ground terminal, an output terminal and the like outside a housing containing and protecting an electronic circuit. Further, by arranging the adjusting terminal inside a connector housing containing terminals such as the power source terminal, the ground terminal, the output terminal and the like, it is possible to prevent contact of foreign objects to the adjusting terminal and to water-proof the terminals for preventing corrosion since an associated connector is attached to the connector when the sensing device is actually used.

Abstract: The present invention is a liquid depth sensing system utilizing the bubble tube or purge operating principle. In this system, a pneumatic tube extends downwardly into the liquid, and air (or other gas) passes through the tube to bubble from the lower end thereof. The air or gas pressure within the tube is equal to the head pressure of the liquid, thus allowing the liquid depth to be determined by measuring the air or gas pressure. The present system may be applied to either open or closed liquid containers (e. g., fuel quantity indication), and may be adapted for use in the bottling industry.

Abstract: Inertial rate sensor and method in which a drive signal consisting initially of a square wave and thereafter a sine wave is applied to a vibratory rate sensing element, a pickup circuit is coupled to the rate sensing element for providing an output signal corresponding to movement of the rate sensing element, the magnitude of the drive signals is adjusted to set a scale factor which determines the sensitivity to movement of the rate sensing element, and a signal in the drive circuit is monitored to detect a failure.

Abstract: The present invention discloses a vibration measuring device for measuring a vibration of an object. Such device includes a sensing body generating a dynamic information in response to the vibration, and a piezoelectric sensing layer disposed on the sensing body to construct a sensor and formed in a distributed mode to measure the dynamic information in a selected specific bandwidth. The present invention also discloses a vibration measuring method.

Abstract: An apparatus 100 for providing information concerning a condition of a vessel such as a steam drum 12 which segregates steam and liquid from one another includes a liquid contact assembly 102, a signal generator element 130, and a housing 112 and a conduit 114 for enclosing the signal generator element 130 in a substantially leak proof manner within the vessel space. The liquid contact assembly 102 is disposable at a first vessel location in the steam drum 12 and has a vibration component 108 operable to vibrate at natural frequencies which vary as a function of a predetermined characteristic of the liquid at the first vessel location and a support component 110 for supporting the water contact assembly 102 in contact with the liquid at the first vessel location. The signal generator element 130 generates a signal indicative of a natural frequency of the vibration component 108.

Abstract: A pressure transmitter with a transmitter housing having an outer wall providing thermal resistance. The outer wall extends from an isothermal island at a first end to a heat sink island at a second end. The isothermal island includes a fluid inlet, and pressure and temperature sensors. The heat sink island includes a primary heat load device that is heat sunk to an outer shell of an electrical connector. The connector contacts carry a current controlled by the transmitter, and a portion of the current is conducted by a primary heat load device. A circuit board controls the current to represent the pressure. A high accuracy, temperature compensated current output represents pressure.

Abstract: A manometer for measuring fluid pressure having a first pressure sensor and a second pressure sensor that is inverted with respect to the first pressure sensor. The first pressure sensor generates a first electrical output signal corresponding to a fluid pressure measured by a first diaphragm of the first pressure sensor. The second pressure sensor generates a second electrical output signal corresponding to a fluid pressure measured by a second diaphragm of the second pressure sensor. The first and second electrical output signals are combined into a combined electrical output signal. False readings of a change in/pressure measured by the first pressure sensor and measured by the second pressure sensor in each of the first and second electrical output signals, due to movement of the manometer, are cancelled by one another in the combined electrical output signal to provide an accurate pressure measurement regardless of movement of the manometer.

Abstract: A semiconductor structure includes an upper and a lower layer of semiconductor material separated by a layer of insulation material. Resistors formed in the upper layer are connected into a Wheatstone bridge arrangement having an output. A first voltage provides power to the bridge. A second voltage connected to the lower layer of semiconductor material has a value selected to reduce the drift of the output following power up of the sensor.

Abstract: A reusable apparatus for forming in situ concrete test specimens comprises a flexible open outer container and a series of smaller closable cylinders for placement within the larger container. The assembly is placed within a depression formed in the wet concrete when the slab is poured, with outer and inner containers being filled with representative concrete of the slab. The assembly is left for the concrete to cure, with smaller containers removed from the larger container after curing. Apparatus is included for facilitating lifting the sample from the slab, after curing. The larger portion of surrounding concrete is then broken away to access the smaller cylinders, which may be shipped to a testing facility where the inexpensive containers are removed to expose the test specimens. The larger outer container may be flexed to remove it from the depression, and the depression filled with fresh concrete to repair the test site.

Abstract: A method of analyzing mechanical actions on an object comprised of a plurality of components includes the steps of creating a model having a general exterior shape of the object without regard to structural details of the components, obtaining separate elasticity coefficients of the model in respectively different spatial directions based on rigidities of the object, and analyzing mechanical actions on the object based on the model and the elasticity coefficients.

Abstract: A method for testing a Coriolis transducer having a mass adapted vibrate along a vibratory direction in a resonant structure and undergo a displacement along a sensitive axis, perpendicular to the vibration, in response to an angular rate about a mutually perpendicular rate sensing axis. In the absence of an angular rate about the rate sensing axis, forces, FTEST VIBRATORY and FTEST SENSITIVE, are applied on the mass along the direction of vibration and along the sensitive axis, respectively, in a predetermined ratio, N. The output VOUT TEST of the transducer is measured in response to the forces, FTEST VIBRATORY and FTEST SENSITIVE.

Abstract: A method for approximating compressible flow is described that is applicable across any pressure range of interest uses upstream and downstream pressure. The approximation minimizes variance with respect to a true flow equation. A flow control system is given using the new method that achieves accurate control with minimum complexities. The control system is application to various systems, including internal combustion engine airflow control, internal combustion engine exhaust gas recirculation control, internal combustion engine alternative fuel flow control, and many other compressible flow control problems.

Abstract: Semi-spherical supports are used in the piercing of small, consistently sized holes in a soft metal. In particular, a flow control device, such as an orifice plate, can be fabricated with small, consistently sized flow apertures to regulate flow in a gas flow regulating device. By using semi-spherical supports, the need for hand-punching and real-time flow calibration can be avoided and automated machinery with a tapered piercing tool can be used to fabricate the flow control device.

Abstract: A pipe connection system has a non-threaded, quick-pipe connection for connecting pipe in a pressurized system, for connecting piping components within a fire sprinkler system, including a flow switch to a fire sprinkler system riser port. A male and female member are attached through the use of a through-slot in the female member that aligns with a groove in the male member such that a locking clip may be inserted through the female and male members when they are joined, thereby blocking the members from being dis-joined. An O-ring seal in a groove on the male member and sealable bore on the female member allow for a sealed and pressurized piping system.

Abstract: Force measuring apparatus that includes a platform and a base for supporting the platform above a supporting surface at only three spaced-apart points. The platform consists of first and second working portions. The first working portion has a first area and the second working portion has a second area. The first area is larger than the second area. The first area is limited to accommodate only an on-line stance. The first and second areas together are limited to accommodate only an in-line stance. The force measuring apparatus incorporates sensor apparatus for sensing loads exerted against the first and second areas.

Abstract: A sensor for measuring torque and position of a shaft having an internal torsion bar. The sensor has a torque sensor, located in the housing and connected to the shaft. The torque sensor has a rotor in electrical contact with a first and second resistive track disposed on an opposed disc. A position sensor is located in the housing and is connected to the shaft. The position sensor has a third contactor mounted to the housing in electrical contact with a third resistive track located on the disc. Several electrical terminals are located in the housing and are electrically communicated with the contactors to provide an electrical signal indicative of the torque and position of the shaft to an external electrical circuit. A slip ring is attached between the rotor and the housing. The slip ring has a fourth and fifth contactor in contact with the torque sensor. The slip ring is adapted to electrically connect the torque sensor to the electrical terminals.

Abstract: A glass container inspection machine has a machine frame to which an inspection device is secured. The inspection device includes a vertical track member, a car vertically displaceable along the vertical track member, a servo operated drive pulley system secured to the vertical track member for vertically displacing the car, an inspection head interconnected with the car for linear, relative displacement and clampable at a desired position. The inspection device is mounted on the frame so that the linear displacement of the inspection head will enable the head to be adjusted to be concentric with the finish of bottles having radially different axes.

Abstract: A method and apparatus are provided for testing a microactuator that forms part of a suspension assembly in a disc drive. The method and apparatus test the microactuator before placing the suspension assembly in a disc drive. In the invention, the head is positioned over a track on a disc based in part on servo information read from the disc. At least one input signal is then applied to at last one microactuator on the suspension assembly. Servo information is then read from the disc to determine a change in the position of the head. By comparing the change in the position of the head to the input signal applied to the microactuator, a performance characteristic of a microactuator can be determined.

Abstract: An apparatus for cycle testing a closure panel of a motor vehicle. The closure panel is coupled to a body of the motor vehicle for articulation about the pivot axis. The closure panel includes first and second laterally spaced apart edges. The first edge is adjacent the pivot axis of the second edge and carries a latch for releasable attachment to the body. The apparatus for cycle testing includes a first linear actuator, a tensioner, and a first flexible coupler. The first linear actuator has a guide track and a carriage mounted to the guide track for repeated movement in alternative directions along a first translation axis between first and second positions. The tensioner is coupled to the carriage of the first linear actuator for movement therewith. The first flexible coupler is attached to the tensioner and coupled to the closure panel adjacent the second edge.

Abstract: A mechanical transmission module has two plates, a transmission mechanism and an actuating axle. The two plates are mounted together with a gap formed between the plates. The transmission mechanism is mounted between the plates. The transmission mechanism can be a Geneva mechanism, a worm and gear mechanism, a belt drive assembly, a threaded rod and slide mechanism, a geared mechanism and so on. The actuating axle extends out from the two plates and drives the transmission mechanism. A connector is secured to a free end of the actuating axle. The connector has a groove and a protrusion in the external face to engage with the groove and protrusion on the connector of another mechanical transmission module. Accordingly, the transmission mechanisms can be modularized and combined with each other. The combination and transmission relations between different types of transmission mechanisms are easily be understood through use of the modules.

Abstract: The XY stage mechanism comprises a Y slide shaft 2 penetrating through only one side surface of the wall surfaces of a vacuum chamber 1 for holding a stage base plate in a cantilevered manner, a Y air slide bearing 4 for guiding the Y slide shaft 2, an X air slide plate 5, a first air slide bearing 6 for supporting the X air slide plate 5, a coupling portion 8, and a second X air slide bearing 9 serving as the guide of the coupling portion 8, whereby, in a state where not only the Y slide shaft is floated up but also the X air slide plate and coupling portion are floated up, the XY stage is driven.

Abstract: A ball spline joint interconnecting an inner shaft and an outer shaft in mutually loose-fitted relation as allowing the shafts to integrally rotate and relatively move from each other in an axial direction. Raceway grooves are respectively formed in the inner shaft and the outer shaft in face-to-face relation and are extended in the axial direction. A plurality of balls are interposed between the corresponding raceway grooves of the inner shaft and the outer shaft, forming an array along the axial direction. A resilient member biases an array-end ball in an angled direction relative to the axial direction.

Abstract: A shift lever is used to remotely operate the change of gear in a set of bicycle gears. The shift lever comprises a housing part and a cable winder with a cable guide which the bicycle user can operate in a winding rotational direction to wind a cable, or in a releasing rotational direction to release the cable. One end of the cable connects interactively with the cable winder, at least in one of the two rotational directions. The housing part has a bar with a guiding edge which together with the cable guide form a cable channel for the cable, from which the cable cannot deviate, if the cable winder is actuated in the releasing rotational directional this occurs if the other end of the cable is not pulled or taken up by the set of gears.

Abstract: A speed controller has a body, a collar interference fit in the through hole of the body, a rotation element having an arcuate extension formed to correspond to an arcuate passage and provided with multiple notches, a sleeve formed to mate with an elongated extension and an elongated protrusion. A user rotates the sleeve to drive the rotation element to accomplish the speed change. Friction between the body and the cable is reduced by removing the lining of the body, so that the force required to operate the speed controller is greatly reduced.

Abstract: A force coupling transfer device for use in marine equipment, snowmobiles, boats, automobiles, machinery, aircraft, recreational vehicles and other industries. The force coupling transfer device allows linear or rotational forces to be transferred from an input device to a controlled device. The force coupling transfer device includes an elongated flexible outer sheath and a movable flexible inner spring member. The inner spring member substantially transfers forces between two remote points located in a control space. The elongated flexible outer sheath is preferably a coiled spring and allows lubricating materials to pass through the surface to lubricate the inner spring member. A strain relief device, which may be a coiled spring, is preferably positioned around the outer sheath, adjacent to its ends, to prevent excessive bending of the outer sheath.

Abstract: A bicycle cable connector for connecting a first cable to a second cable includes a first connector and a second connector. The first connector include a first cable retaining portion for retaining the first cable and a projection extending along a first connector axis, wherein the projection includes a radially outwardly extending locking member. The second connector includes a second cable retaining portion for retaining the second cable and a tubular portion defining a first connector opening for receiving the first connector therein and having a side wall extending along a second connector axis. The side wall includes a first passage for passing the locking member in the direction of the second connector axis away from the first connector opening, a second passage extending in a circumferential direction, and a recess communicating with the second passage and extending in the direction of the first connector opening for receiving the locking member therein.

Abstract: A method of operating a control pedal assembly includes the steps providing a pair of adjustable control pedals. Each control pedal includes a first support and a second support having a lower arm and moveable relative to the first support to adjust the fore-aft position of the lower arm upon operation of a motor. A predetermined fore-aft relationship is provided between the lower arms of each of the pair of control pedals. The predetermined fore-aft relationship is maintained during operation of the motor to move the second supports relative to the first supports while adjusting the fore-aft position of the lower arms. The motor is stopped during operation if the predetermined fore-aft relationship between the lower arms is not maintained.

Abstract: A control cam or a gear wheel having a plurality of layers of flat material placed one on top of the other. Each of the layers of flat material is of a multi-part form with partition lines that extend in a direction of planes over the layers of material. At least some of the partition lines of neighboring layers of the flat material are offset in relation to one another. The partition line of a layer of flat material is arranged so that in both circumferential directions it lies approximately equally spaced in relation to a partition line of a neighboring layer of flat material.

Abstract: A composite control arm shaft for motor vehicles includes two longitudinal control arms connected through a transverse beam, wherein the transverse beam has a trough-shaped double-wall torsion section essentially having the form of a V or U, approximately circular or oval tubular end sections and transition sections whose cross-section continuously changes from the end sections toward the torsion section. The transverse beam has in the transition sections thereof an internal partial foam filling.

Abstract: The present invention is a automatically tightening pedal strap, which has a front member sized and shaped for placing a user's front of a foot in a shoe into the device. The front member has a top portion and a bottom portion. The bottom portion includes a strap tightening driver moving mechanism for moving connecting device forwardly wherein the strap tightening driver moving mechanism moves in response to insertion of one's foot in a shoe into the device. There is also connecting device connecting the strap tightening driver moving mechanism and a strap member in which, when the strap tightening driver moving mechanism is moved forward within the front member, the strap member automatically tightens by movement of the connecting device on the strap member in response to the forward movement of the strap tightening driver moving mechanism. The strap tightening driver moving mechanism may be a slider or an end string attachment.

Abstract: An improved structure of a ratchet wrench is disclosed. The structure has a plurality of engaging teeth on a teeth member and a ratchet wheel, characterized in that at least a cavity hole is appropriately provided on the engaging teeth and is mounted with an elastic body therein, thereby, when the teeth member is engaged with the ratchet wheel, the elastic body of the engaging teeth produces a small gap, by the elastic force of the elastic body, between the teeth member and the ratchet wheel, allowing a smooth teeth-returning between the teeth member and the ratchet wheel.

Abstract: A hex wrench storage member includes a tubular body that has a recess defined in the body and communicating with an outer periphery of the body at a first opening and communicating with an end of the body at a second opening. The recess is defined by several stepped surfaces each of which receives respective one of two ends of the hex wrenches and the other end of the hex wrench protrudes from the recess so that the tubular body can be used as a T-bar handle. A plurality of holes are defined in an end of the body so as to respective receive the hex wrenches.

Abstract: A folding multipurpose tool incorporating a latch release mechanism including a lever, a cam, and a rocker-shaped grip body to easily effect release of a catch for holding knife or screwdriver blades extended spring and cams are arranged to hold a pair of handles either extended or folded with respect to the tangs of a pair of pliers jaws or the like. The handles include inwardly directed comfortable rounded rims. Portions of folding blades interlock with other folding blades on an opposite handle when the tool is folded, to stabilize the handles while using a knife or screwdriver. Blades of folding scissors include edges that are serrated only near their tips. A container opener includes a hook defining a recessed throat.

Abstract: A bit holder for a battery-powered screwdriver. A compartment is formed on one end of the screwdriver, opposite the tool bit driving end of the screwdriver. A sleeve mounted in the compartment can be slidably moved between open and closed positions. A plurality of bit holding clips are fixed around the sleeve's outer circumference. A shaft extends through the compartment. One of the shaft's ends is fixed at the compartment's forward end. The sleeve is slidably mounted over the shaft's opposite end.

Abstract: A multi-spindle machine system includes a pick-up attachment. Both the rotational and the axial positions and speeds of the pick-up spindle may be selectively controlled. A plurality of clutches may be used to rotate the pick-up spindle at different speeds. The clutches operatively engage respective drive gears to drive the pick-up spindle. A brake may be used to slow or stop the pick-up spindle. A servo motor may alternatively be used to rotate the pick-up spindle at different speeds. Another servo motor may be used to axially position the pick-up spindle at different locations. The pick-up attachment of the system of the present invention provides selective programmable control of the movements of a pick-up spindle during work piece pickup, back machining, and dropping operations.

Abstract: A wood-turning lathe includes a driven shaft mounted with a pulley unit having a plurality of angularly spaced retaining holes, a spring-biased pin and a cam member associated with both the pin and the pulley unit. When the cam member is moved to a locking position, the pin is urged by the cam member to engage a selected one of the retaining holes in the pulley unit to immobilize the pulley unit. When the cam member is moved to an unlocking position, the pin disengages from the selected one of the retaining holes in the pulley unit to permit rotation of the pulley unit.

Abstract: A die apparatus includes a first die configured to telescopingly engage an end section of a tubular bar, including one or more “floating” mandrels configured to extend into cavities of the tubular bar, and further including a stationary die member spaced from the mandrel(s). The mandrel(s) and the stationary die member include angled cutting edges that are aligned so that the cutting edges are engageable from a single transverse direction. The mandrel(s) is movably supported on the first die to float parallel the single direction toward and away from the stationary die member. A cutting die has a shearing punch configured to move along the single direction to sequentially engage the angled cutting edges to shear off an angled portion of the end section.

Abstract: Apparatus includes a first member and a second member. The first member includes a first surface and the second member includes a driven member. The second member is movable relative to said first member between a first position and a second position, wherein the driven member is closer to the first surface in the second position than in the first position. The second member includes an inlet, an outlet, and an enclosed pathway between the inlet and the outlet. A collector is movably coupled to the second member at the inlet and communicates with the inlet.

Abstract: An apparatus for cutting segments from a long sheet of multilayered elastomeric material. An initial opening is formed in the sheet without severing reinforcing cords within the elastomeric sheet by a penetrator/separator. Two ultrasonic knives are inserted on either side of the penetrator/separator and positioned to cut the sheet at a small skive angle &agr; with respect to the plane of the sheet being cut. Then the knives are moved to opposite edges of the sheet of elastomeric material.

Abstract: The present invention pertains to a cable saw (1) with a frame (2), a motor drive (7) and a driven cable storage unit (6) for the sawing cable (3) moved in a circulating manner. The drive (7) has a plurality of adjacent drive wheels (11, 12), around which the sawing cable is wound and which together are driven by a motor (8). The motor (8) and optionally an interposed gear (9) are removable by means of a change-over coupling (10). In addition, the cable saw (1) can be broken down into at least three basic components, namely, a main roller head (34), a frame unit (35), and a motor unit (36).

Abstract: A braiding machine has a support defining an upright axis, a lower rotor rotatable on the support about the axis and defining an annular guide centered on the axis, and an upper rotor having slides bearing at an interface on the guide and rotatable on the lower rotor about the axis. A drive connected to the rotors rotates same in opposite directions about the axis with the slides sliding on the guide. Dosers feeding a lubricant to the interface and a sensor detects a temperature of the guide at the interface. A computer-type controller connected to the doser and to the sensor feeds the lubricant to the interface at a rate only sufficient to prevent the detected temperature from exceeding a predetermined limit.

Abstract: A weapon system and method is provided to obtain damage assessment data immediately after impact of a missile. The missile releases the pod a short time before impact. The pod contains a parachute, a small camera and communications equipment. When released, the pod deploys the parachute to slow its descent and to direct the camera to the proper orientation so as to capture the impact and damage resulting from the impact. Using its communications equipment, the pod relays the impact and resulting damage data back to launch control. The system and method thus provide launch control with immediate battle damage assessments without requiring a launch platform to remain in the battle arena, or without requiring a reconnaissance platform to enter the arena to obtain the damage assessment data.

Abstract: An armoring system for vehicles, vessels, aircraft and structures. A plurality of discus-shaped disks are individually wrapped in a containment wrap. The wrapped disks are laid out in an imbricated pattern and adhered in place between a pair of fibrous layers. In one embodiment an elastomer layer is used to seal the panel to prevent degradation from exposure to environmental factors.

Abstract: The present invention relates to an automatic bolt hold-open rotating assembly to convert a manual bolt hold-open function to an automatic bolt hold-open function in automatic and semi-automatic pistols and rifles, such as the Ruger 10/22 semi-automatic .22 caliber rifle. The components of the assembly readily replace standard factory components in the trigger assembly and replace the standard magazine. The assembly comprises a magazine with channel cutout, a bolt stop, a bolt stop handle for manual manipulation of the assembly, a bolt stop spring to apply clockwise pressure on assembly, a cartridge detecting lever which also serves as a cartridge ejector pivotably mounted on bolt stop with an extension which interfaces with channel cutout of magazine, a tab protruding from the ejector lever which rides in a slot on the bolt stop to limit pivoting of the cartridge detecting lever, and a lever spring allowing counter-clockwise pivoting of cartridge detecting lever to facilitate insertion of recharged magazine.

Abstract: An electronic bore pressure optimization mechanism for dynamically varying the cylinder block piston bore pressure profile in a multiple piston hydraulic unit includes a valve means having a variable orifice disposed in the end cap for metering fluid between leading and trailing pistons in a transition region or between a piston in a transition region and a high or low pressure source; and means for generating a control error signal to the valve means so as to adjust the size of the variable orifice based upon the control signal.