Abstract: A force fight mitigation system comprising: control means configured to provide a position command to each of two or more actuators arranged to position a surface, the position command indicative of a desired position of the actuator relative to the surface; means to detect the actual position of the actuator relative to the surface in response to the position command; and means to determine an offset between the desired position and the actual position and to store a rigging correction based on the offset; wherein, for each actuator, an offset is determined for each of three or more desired positions.

Abstract: A method of customizing the cooling of a first heat-producing system comprises selecting a first set of cooling fins with a deployment level. The method also comprises analyzing environmental data for an environment associated with the first set of cooling fins. The method also comprises quantifying a cooling benefit of the deployment level. The method also comprises quantifying an airflow detriment of the deployment level. The method also comprises determining that the airflow detriment outweighs the cooling benefit. The method also comprises reducing the deployment level based on the determination.

Abstract: A hydraulic arrangement. The hydraulic arrangement has multiple hydraulic units, the control units of which are connected, in particular in series, via a data connection. The control units are preferably designed to control selectively only hydraulic cylinders directly associated with said units, or also indirectly control, via the data connection and the control unit of an additional hydraulic unit, the hydraulic cylinders associated with said additional hydraulic unit. A climbing formwork having at least one climbing unit, in particular multiple climbing units. The hydraulic units can be linked via the data connection such that synchronous lifting and/or lowering of all climbing units can be or is achieved. The hydraulic units are preferably connected in a master-slave arrangement or are preferably controlled in a master-slave mode. Also preferably, the hydraulic units are designed to switch from the master-slave mode to the stand-alone mode.

Abstract: This invention discloses in particular an actuation cylinder (10) for controlling the movement of a ring-gate (40) of a hydraulic machine, said actuation cylinder (10) comprising a body (18) forming a first chamber (22) provided with a first duct (26) and a second chamber (24) provided with a second duct (28) which are designed to receive an actuating fluid through said first duct (26) and said second duct (28), said chambers being separated from one another by a piston (20) connected to an actuating rod (14) and able to move in said body in a first direction in which the volume of the second chamber increases while the volume of the first chamber decreases, and in a second direction in which the volume of the second chamber decreases while the volume of the first chamber increases, said piston being provided with a rod (30) connected in said second chamber to an area (20b) of the piston turned toward said second chamber, said area (20b) having a surface less than an area (20a) of the piston turned toward the

Abstract: A hydraulic cylinder comprising a cylinder, a piston element movably guided in the cylinder in a working direction and comprising an active surface, and a first opening for feeding a fluid into a cylinder chamber by the active surface. A working pressure of the fluid acting on the active surface drives the piston element in the working direction. The active surface includes a first partial surface and at least one second partial surface, the cylinder chamber being divided into a first sub chamber with the first opening by the first active surface and a second partial surface with a second opening by the second partial surface, and the partial surfaces are hydraulically separated from each other at least in a selectable operating mode.

Abstract: A system of pumps wherein a first hydraulic motor operatively connected to a first master pump can hydraulically drive a second hydraulic motor operatively connected to a second slave pump. A hydraulic fluid outlet of the first hydraulic motor is fluidically connected to a hydraulic fluid inlet of the second hydraulic motor whereby the first hydraulic motor, operatively connected to the first pump, drives the second hydraulic motor, operatively connected to the second pump, in a hydraulically synchronized manner.

Abstract: A method and apparatus for controlling movement of a component in a system by a plurality of actuators. An operation actuation command to move the component is received. For each of the plurality of actuators, the operation actuation command is used to generate a feed-forward equalization command for the actuator, the feed-forward equalization command for the actuator is combined with the operation actuation command to provide an equalized actuation command for the actuator, and the actuator is controlled to move the component using the equalized actuation command for the actuator.

Abstract: A method for controlling the operation of a gas turbine includes monitoring an operating parameter of the gas turbine engine. The method also includes determining a first position demand for controlling an operation of a first actuator based on the monitored operating parameter. In addition, the method includes controlling the operation of the first actuator based on the first position demand to adjust the angular position of at least one airfoil included within a first array of airfoils. The method further includes determining a second position demand for controlling the operation of a second actuator based on the first position demand. In addition, the method also includes controlling the operation of the second actuator based on the second position demand to adjust the angular position of at least one airfoil included within a second array of airfoils.

Abstract: A fluid power control system for load handling mobile equipment includes a pair of hydraulic actuators for moving respective cooperating load-engaging members selectively toward or away from each other, or in a common direction, at respective asynchronous speeds to selectively attain either synchronous or asynchronous respective positions of the actuators. The actuators have sensors enabling a controller to monitor their respective movements and correct unintended differences in the actuators' respective movements, such as unintended differences in relative intended positions, speeds, or rates of change of speeds. Respective hydraulic valves responsive to the controller separately and nonsimultaneously decrease respective flows through the respective actuators to more accurately and rapidly correct differences from the intended relative movements of the actuators.

Abstract: A device controls the movement of a ring gate of a hydraulic machine between an open position and a blockage position. The device includes at least four cylinders, the rods of which are suitable for being connected to the ring gate at locations located on a perimeter of the ring gate. The device also includes at least two hydraulic members for synchronizing pistons, the hydraulic synchronization members being connected to the cylinders such as to form at least two groups. Each group encompasses at least two cylinders connected by at least one hydraulic synchronization member, two cylinders belonging to two separate groups not being connected by a hydraulic synchronization member.

Abstract: This disclosure includes hydraulic apparatuses and methods for redundant actuation of a hydraulic device. Some apparatuses include a hydraulic device having a first hydraulic actuator and a second hydraulic actuator, wherein each of the first and second hydraulic actuators comprises at least a first hydraulic cavity, a second hydraulic cavity, and a piston. Some apparatuses also include a controller coupled to the hydraulic device. In some embodiments, the controller is configured to receive hydraulic fluid from a fluid source via at least two parallel hydraulic lines coupled to the controller, select a first hydraulic line of the at least two parallel hydraulic lines, and transfer the hydraulic fluid from the selected first hydraulic line to a first cavity of the first hydraulic actuator to apply pressure to a first piston to actuate the hydraulic device.

Abstract: An AC motor hydraulic system which utilizes a plurality of centrally controlled AC servo motor driven hydraulic pumps with integrated reservoirs to effectuate rotation of a plurality of stabilizer fins mounted about a vessel to automatically counter unwanted movement of a vessel.

Abstract: Device together with hydraulic system for actuating at least one first hydraulic consumer and at least one second hydraulic consumer.

Abstract: The invention relates to a hydraulic wheel set press for the simultaneous pressing of two wheel (1, 2) or brake disks on a wheel axis (3) having a frame construction (4) mounted on a base (5), said frame construction being comprised of two identical vertical press stands (6, 7) connected to one another in a fixed manner at a mutual distance via horizontal traverses (8, 9). The press stands (6, 7) each have a housing (10, 11) serving to accommodate a centering cylinder (12) engaging the wheel axis (3) on one end (14 15). In addition, a press cylinder (13) is provided concentrically to the centering cylinder (12). said press cylinder engaging the wheel (1, 2) or brake disk to be pressed, as well as control devices (22) for loading each of the two cylinders (12, 13) with a pressure medium.

Abstract: What is disclosed is a hydraulic control system for a mobile equipment, in particular for a wheel or backhoe loader, wherein a shovel is linked to a boom. The angular position of the shovel may be kept constant through the intermediary of an orientation control device during a pivoting movement of the boom relative to the axles of the equipment. In accordance with the invention, the orientation control device is realized such that in the event of a change of a pre-set angular position, a control signal is generated through a pilot control device, whereby a shovel control unit may be controlled in such a manner that the shovel is again returned into its predetermined angular position.

Abstract: An object of the invention is to propose a hydraulic lift structure which prevents a malfunction of a hydraulic cylinder or the like and improves a supplying and discharging efficiency of a working fluid. In a hydraulic lift structure formed by arranging a hydraulic cylinder case internally provided with a hydraulic cylinder for moving up and down a working machine (a rotary power tiller) in an upper portion of a transmission case of a working vehicle, an oil reservoir of a working fluid for the hydraulic cylinder is provided in a boundary portion between the transmission case and the hydraulic cylinder case in such a manner as to be isolated from an inner portion of the transmission case.

Abstract: Synchronizing hydraulic cylinders is provided by interconnected double-acting cylinders with dual pistons and central dividers which, with the pistons, divide the cylinders into four chambers. The outer chambers drive the pistons and the loads attached to the piston rods. The inversely interconnected intermediate inner chambers synchronize and balance piston and load movement. In double piston divided cylinders opposite outer chambers move a connected load and reversely connected inner chambers synchronize the load.

Abstract: Vehicle lifting device comprising a number of columns, guides on each column for guiding a carriage for substantially vertical displacement along the column, which carriage bears vehicle supports. Lifting supports engage on the columns and the carriage. The lifting supports are connected to a motor, and a synchronization system for causing the carriages of all columns to run synchronously. The lifting supports of each column are provided with their own motor.

Abstract: A self-propelled combine harvester having a mechanically actuated directional control valve for a hydraulic piston-cylinder unit used for driving the cutter bar in an oscillatory manner. A switching bracket is used to axially move the mechanically actuated directional control valve from a first end position to a second end position and from the second end position to the first end position. A latch is used to periodically latch a piston valve stationary. A first plunger and second plunger are alternatively and axially moved by a first spring and second spring. The first plunger and the second plunger alternatively move the valve piston from the first end position and the second position and from the second position to the first position. The valve piston will be released from the first end position or the second end position one end position from which it was arrested or latched.

Abstract: A method and apparatus for lifting a work implement attached to a work machine. The method and apparatus includes delivering a lift command to a hydraulic lift circuit, diverting a portion of the lift command to a hydraulic tilt circuit, and responsively tilting the work implement to a rack-back position in cooperation with lifting the work implement.

Abstract: A hydraulic actuating device for a device having a first and a second hydraulically moveable component for a convertible-top assembly of a vehicle. The actuating device comprises two hydraulic actuators, each having a first and a second connection for supplying and discharging hydraulic fluid in order to displace the piston/piston rod assembly.

Abstract: A closed circuit synchronizing cylinder assembly for synchronously moving at least two external devices such that the devices move at the same rate and maintain essentially the same level within a small deviation. The synchronizing cylinder assembly has a cylinder with a movable piston and rod for each external device. The piston divides the interior of the cylinder into a rod outer diameter chamber, a rod inner diameter chamber and a third chamber. The rod outer diameter chamber and rod inner diameter chamber have equal areas and hydraulic fluid therein and third member is open to atmosphere. The hydraulic fluid in the rod outer diameter chamber of one cylinder communicates with the rod inner diameter chamber of another cylinder driving the reciprocal movement of the piston and rod.

Abstract: A method and apparatus for minimizing the loader frame stress induced by the twisting action which results from unequal travel in the actuators. The method includes the use of electro-hydraulics in conjunction with feedback from actuators displacement sensors. Each actuator is controlled by an individual control valve. The amount of extension of each actuator's piston is monitored. Control signals are sent to the control valves which control fluid flow to each actuator to maintain the actuators' piston extensions at the same amount.

Abstract: A hydraulic valve system for controlling and synchronizing the flow of hydraulic fluid to a set of first and second hydraulic actuators powered by a single control valve work section. The system includes a primary control valve or valves and a synchronizing control valve. The primary control valve is actuated to control the flow of hydraulic fluid between a source of pressurized hydraulic fluid and both the first and second cylinders, and includes an input port connected to the source of pressurized hydraulic fluid and an output port connected in a parallel hydraulic circuit to both the first and second cylinders. The synchronizing control valve is actuated to synchronize the flow of hydraulic fluid from the primary control valve to the first and second hydraulic cylinders by bleeding a portion of the flow of hydraulic fluid supplied to one of the cylinders to the tank. The synchronizing control valve has first and second input ports and an output port.

Abstract: A pneumatic pump pumps liquids from natural gas wells. First and second pneumatic rams have first and second pistons housed in first and second cylinders with a lifting beam connecting the first and second pistons above the first and second cylinders and connectable to sucker rods for lifting liquids from a well. First and second gas connections are provided beneath the first and second pistons in the first and second cylinders. First valves are connected to the first and second gas connections to introduce compressed gas beneath the first and second pistons for raising the lifting beam during an upstroke of the sucker rods and a first control valve regulates the up-stroke rate of the lifting beam. Second valves are connected to the first and second gas connections to exhaust gas beneath the first and second pistons for lowering the lifting beam during a down-stroke of the sucker rods and a second control valve regulates the down-stroke rate of the lifting beam.

Abstract: A hydraulic control circuit comprises a power unit, a central processing unit, at least one feedback sensor, a valve manifold, and two or more hydraulic lifting cylinders interconnected with miscellaneous hydraulic hoses and electrical wiring. Basic lifting is regulated by a flow divider unit configured to distribute a flow of pressurized hydraulic fluid pumped from a fluid reservoir through the valve manifold to each of the lifting cylinders during a lifting operation. To compensate for any imbalance between the lifting cylinders, the central processing unit monitors the movement of the lifting cylinders, and is configured to divert, through a three-way valve in the valve manifold, an additional portion of the pressurized fluid flow to a lagging lifting cylinder.

Abstract: An arrangement for assuring synchronous motion of a pair of actuators (65, 67) includes two gear racks (99, 101) moved by cables (95, 97) fixed to remote hydraulic actuators (65, 67) to sense the motion of the actuators (65, 67). The racks (99, 101) drive pinions (111, 113) and attached bevel gears (113, 115) at identical rates and an idler bevel gear (119) that spins in-place on its own axis when actuator travel is synchronous. When the actuator (65, 67) travels are synchronous, no error signal is sent to a synchronizer servo valve (105), however, when one actuator's speed is too great, an output error signal from the idler gear (119) is sent. The output signal positions a servo valve (105) to release pressure which is holding open one of two throttling valves (107, 109). Releasing the pressure allows the throttling valve (107, 109) to be closed by a spring (129, 131) and restrict flow to the actuator (65, 67) which is traveling the fastest.

Abstract: A method and system are used to calibrate a plurality of actuators joined to an actuation ring in a control system for vectoring exhaust flaps in a vectoring nozzle. The actuators include output rods which are positioned to respective first positions at which output stroke is measured. The actuators are repositioned to different second positions, and the output stroke thereof is again measured. The stroke measurement for each of the actuators is calibrated to effect a common linear response between the first and second measurement positions. The calibrated actuators ensure coordinated linear actuation thereof as the output rods are positioned between their minimum and maximum extensions.

Abstract: A hydraulic synchronizing circuit includes at least one master cylinder unit including a primary chamber, a secondary chamber, a piston and at least one piston rod, the piston having a primary effective surface and a secondary effective surface. The hydraulic synchronizing circuit further includes at least one slave cylinder unit including a primary chamber, a secondary chamber, a piston and at least one piston rod, the piston having a primary effective surface and a secondary effective surface. The master cylinder unit and the slave cylinder unit are arranged to be single-acting. The secondary effective surface of the master cylinder unit and the primary effective surface of the slave cylinder unit are substantially equal. A tank at least partially formed by the secondary chamber of the slave cylinder unit and containing a fluid is provided. A pump sucks the fluid from the tank. A first conduit operatively connects the tank to the primary chamber of the master cylinder unit via the pump.

Abstract: A hydraulic platform lift for trucks, having hydraulic and electrical circuitry to provide automated, or automated with manual override, platform levelling capability in the event the truck is tilted. Three embodiments are claimed where levelling may be accomplished in three separate ways; a first embodiment where levelling is accomplished by stopping one side of the platform and allowing the other side to "catch up", a second embodiment where levelling is accomplished by reversing the direction of movement of one side relative to the other to allow rapid levelling, and a third embodiment where the rate of movement of one side is slowed relative to the other, to allow the other side to "catch up" and thereby level the platform.

Abstract: A dual hydraulic oscillator for the reciprocating cutter of an agricultural machine is provided. The dual oscillator has two pistons reciprocating in opposite directions and a single pilot valve, with resynchronization performed twice per cycle of the oscillator. Also provided is a single or dual hydraulic oscillator comprising a cylinder having first and second opposed ends. A reversing pilot valve is provided for controlling flow of pressurized fluid to at least one of the first and second cylinder ends. The pilot valve includes first and second pilot passages for controlling the reversing operation of the pilot valve. A piston reciprocates between first and second positions in the cylinder. The piston has an inner bore. The bore has first and second circumferential logic grooves. An inner logic mechanism is slidably received in the bore.

Abstract: A cylinder positioning control apparatus designed to effect positioning of a cylinder by learning control that uses not only an overrun distance but also a cylinder speed as input data for control. The apparatus has a device for taking in a displacement x and speed V of a cylinder, a device for calculating a predicted overrun distance y.sub.i for the present drive from a predicted overrun distance y.sub.i-1 in the preceding drive, a cylinder speed V.sub.i-1 at the time of outputting a braking signal during the preceding drive, and a speed V.sub.i of the cylinder being driven, a device for judging whether or not a condition to be satisfied to output a braking signal is satisfied, and for outputting a braking signal when the condition is satisfied, a device for taking in a displacement x.sub.bp and speed V.sub.bp of the cylinder when the braking signal is output, a device for taking in a displacement x.sub.stop of the cylinder when it has stopped, and a device for calculating a predicted overrun distance y.sub.

Abstract: An apparatus for synchronizing the extension and retraction of linear actuators. A quadrilateral structure is formed by means of the support base, a pair of actuators, and a crossmember, with a sensor positioned so as to detect variations in the shape of the quadrilateral. The sensor functions in cooperation with the actuator control mechanism to vary power to the actuators in response to the changes in shape which occur due to slight variations in actuator speed of movement.

Abstract: The piston rods (10, 12, 14) of three linear hydraulic motors (M1, M2, M3) are stationary and include fluid pressure passageways (40, 52, 42, 54, 44, 56) which direct fluid pressure into and out from working chambers (16, 34, 18, 36, 20, 38) on opposite sides of piston heads (22, 24, 26). Movable cylinder barrels (16, 18, 20) are connected to a load, e.g. floor members (FM1, FM2, FM3) of a reciprocating floor conveyor (FIG. 18). The outer ends of the piston rods (10, 12, 14) include balls and the balls include ports (46, 58, 48, 60, 50, 62) through which fluid pressure is delivered or removed. Associated with each port is a limit valve LV1, LV2, LV3, LV4, LV5, LV6. Limit valves (LV1, LV2, LV3) are pushed into an open position by a retraction of the motors (M1, M2, M3). Limit valves (LV4, LV 5, LV6) are pulled into an open position by extension of motors (M1, M2, M3). The limit valves (LV1, LV2, LV3, LV4, LV5, LV6) includes springs biasing them into closed positions.

Abstract: A dual servo actuation system is automatically equalized or rigged by electronic control circuits. A static auto rigging bias is applied to one or the other, or both, of a pair of electro hydraulic servo valves that respectively control two hydraulic actuators driving a common member, such as an aircraft control surface. An auto rigging bias, which substantially eliminates force fight, is automatically generated and stored as a fixed quantity prior to use of the system for control of the common member. With a zero commanded output of the two actuators, a difference of differential pressures at the actuators is obtained and caused to change the number in a counter as long as the difference exceeds a threshold. The counter number, while it is above the threshold, is continuously applied as a bias signal to decrease the force fight, and the number in the counter is stored as a fixed bias signal when the force fight indicated by the difference of differential pressures drops below the threshold.

Abstract: Hydraulic fluid under pressure is selectively supplied to multiple drive cylinders that are interconnected to one another and which have bypass lines allowing excess fluid to return to the source of hydraulic fluid as needed. Each drive cylinder receives a double acting piston and each piston is carried by and axially displaces a component pump shaft as it reciprocates within the drive cylinder under the influence of hydraulic pressure. A free end of each pump shaft carries a trip member that trips upper and lower limit switches when the piston reaches its top dead center and bottom dead center positions, respectively.

Abstract: A hydraulic platform and level correcting system used for a wide variety of lifting applications that require a steady, level lift in order to avoid damage to the lift and/or an object being lifted. The hydraulic platform is controlled by an electrohydraulic control system which includes a hydraulic pump under the control of an electric control circuit to provide the lifting force necessary for hydraulic platform operation as well as a device for automatically correcting the level of the hydraulic platform.

Abstract: Either a reciprocating or a stationary part in each of juxtaposed cylinder devices is provided with a scale having alternate projections and depressions which are arranged with regular pitches in a direction of reciprocation of the reciprocating part, while the other part is provided with a sensor engaging the scale for determining whether it is a projection or depression of the scale that the sensor engages at a particular point of time, and producing a pulse whenever it falls in any of the depressions. According to one preferred embodiment, the projections and the depessions of the scale of one of the cylinder devices are staggered relative to those of the scale of the other cylinder device by half a pitch. Thus, when the two cylinder devices are in synchronous operation, the sensors of the cylinder devices produce alternate pulses which do not overlap with each other in the time of occurrence.

Abstract: A hydraulic system having multiple actuators is provided with positive pressure flow equalization for both advancing and retracting movements of the system by means of first and second flow divider elements for each actuator. The flow divider elements are cross-coupled between the actuators, a controllable source of pressurized fluid and a reservoir. The flow divider elements are positive-displacement gear or vane pump units that are connected by a common shaft for coordinating fluid flow to the various actuators. Two or more of the actuators can be connected for lifting a load such as an automobile, the system being provided with safety latches at each actuator, the flow dividers not only coordinating the actuator movements during normal raising and lowering operation, but also preventing loss of synchronization of the actuators in case of engagement of a subset only of the latches.

Abstract: A system reduces force fight between hydraulic actuators (22, 24) operated on independent hydraulic circuits (29, 49) which position a control surface (20) of an aircraft. Each circuit includes a hydraulic supply (30, 50). A pressure equalization valve (70) is connected to first sides (42, 62) of the actuators. In the event of a pressure imbalance, a spool (82) shifts in the pressure equalization valve. Movement of the spool enables fluid from the circuit supply to be delivered through the equalization valve to the actuator at the lower pressure, rapidly eliminating the imbalance.

Abstract: The present invention relates to, in combination, a vehicle utilizing a first hydraulic cylinder to operate lifting means and a second hydraulic cylinder to operate end effector means, each of the cylinders including a piston, the pistons when moved toward their "up" sides causing the lifting means and end defector means to move in a first direction and when moved toward their "down" sides causing the lifting means and means to move in a second direction, and a load self-leveling system for the vehicle, the system comprising a pair of fluid flow dividers interposed in flow lines between a source of hydraulic fluid under pressure and the first and second hydraulic cylinders, the flow dividers being structured to direct a greater flow of hydraulic fluid to the first cylinder and a lesser flow to the second cylinder, each of the flow dividers comprising adjustable spool valve means located in flow passages between the source of hydraulic fluid and the first and second hydraulic cylinders.

Abstract: A fluid servomechanism has a first actuator driven by fluid, a second actuator, and a pressure generator for generating pressure corresponding to the difference in displacement between output shafts of the first and the second actuators. Therefore, a compact-size finger facilitating angularly free movement and having a highly elaborate human-like function can be attained.

Abstract: A universal control system for hydraulic cylinders to enable controlled increments of movement for varying uses including shaping members and lifting and lowering of loads. The lift control system is utilized to synchronize the raising or lowering of a load by, for example, four simultaneously-acting pump-operated hydraulic rams which have plural increments of movement. A sensor associated with the load adjacent each ram measures incremental movement of the load. A master controller controls the operation of the rams in accordance with the sensed increments and operates each pump simultaneously and independently until each pump achieves a preselected increment of movement of a ram, to maintain the load substantially level, followed by movement of all the rams through another increment of movement until the total lifting or lowering movement is achieved.

Abstract: A method of operating a boom which comprises an elongate member mounted on a base for pivotal movement about a first axis transverse to the axis of the elongate member, first fluid operated power means mounted between the base and the elongate member to control raising and lowering of the member about said first axis, an implement mounted at one end of the member for pivotal movement about a second axis transverse to the axis of the elongate member, second fluid operated power means comprising a double acting ram having a cylinder and plunger slidable therein, mounted between the implement and the member to control movement of the implement about the second axis, means to feed fluid under pressure to and from the first fluid operated power means along first feed lines via a first operating valve, means to feed fluid under pressure to and from the second fluid operated power means along second feed lines via a second operating valve, a displacement means comprising a further double acting fluid operated ram co

Abstract: A multiple fluid pumping system uses two or more fluid pumps each driven by a pneumatic piston or plunger and cylinder combination whose piston top stroke and bottom stroke positions are detected by reed switches in combination with a magnet attached to the piston. The top stroke reed switches are connected in series with one side of a two position pneumatic solenoid valve while the bottom stroke reed switches are connected in series with the other side of a two position pneumatic solenoid valve. The circuit is designed to prevent one of the pistons from changing the direction of its stroke prior to the other piston reaching the end of its stroke. A further embodiment utilizes a magnet mounted on one pneumatically driven piston or plunger and a pair of reed switches mounted on the other pneumatically driven piston or plunger to prevent one piston or plunger from moving faster or slower than the other piston or plunger.

Abstract: A fluid powered actuator system includes two identical fluid powered actuators operable by respective supply pressures which are controlled by respective identical valve arrangements. Operating positions of flow control elements of the valve arrangements are applied through respective couplings to a differential arrangement which operates, if these positions differ by an unacceptable amount, to apply an error indication through respective coupling to prevent the supply pressures from being applied to the respective actuators.

Abstract: In a sensitive analytical instrument having an optical bench carried by a base member, new and improved vibration and shock isolation apparatus which includes three spaced pneumatic mounts interposed between the optical bench and the base member to provide vibration and shock isolation therebetween, each of the mounts having a preselected optimum linear range of operation, a source of pressurized gas, apparatus for individually controlling the inflation and deflation of each of the mounts with pressurized gas to maintain actual operation of each of the mounts within its preselected optimum linear operating range.

Abstract: A hydraulic system for lifts provided with two independently supported parallel platforms comprises at least two cylinder-piston units (80, 81) for raising the platforms, a metering device (7) for feeding identical quantities of fluid to said two units, and a balancing device (74, 75) operated by means (31, 32) for measuring the height difference between the platforms and arranged to feed a quantity of supplementary fluid to that cylinder-piston unit (80) or (81) operating the lower platform by withdrawing it from that cylinder-piston unit (81) or (80) operating the higher platform.

Abstract: A load self-leveling system for a vehicle utilizing hydraulic cylinders to operate a telescopic lifting boom and a material handling carriage. The system includes a pair of fluid flow dividers interposed between the source of hydraulic fluid under pressure and the hydraulic cylinders operating the boom and carriage. The flow dividers are structured to direct a greater flow of hydraulic fluid to the boom cylinder and a lesser flow to the carriage cylinder, the precise numeric proportions of flow division being engineered to best suit a particular vehicle, combined with the specific componentry of that vehicle. In addition to the flow dividers, the system includes reversible flow piloted check valves, override control including override relief valves to allow independent adjustments, and matched cylinder area ratios. A compact assembly housing various of the components comprising the system is disclosed.

Abstract: A dual automatic leveling system for a blast hole drill during raising and lowering which includes "fine" level sensors to detect an attitude within a fine level range and "coarse" level sensors to detect an attitude outside a coarse level range which is greater than that of the first. A controller is connected to the sensors as well as to appropriate valving with a pressurized fluid source so as to operate hydraulic jacks. The jacks are activated in a first mode in conjunction with the "fine" sensors and in a second mode in conjunction with the "coarse" sensors. In a preferred manner, the "fine" and "coarse" level sensors are positioned as front, rear, and end level sensors mounted on the main frame of the blast hole drill. The "fine" level sensors in conjunction with a programmable logic control will initially level the drilling platform within a .+-.0.5.degree. (both transverse and longitudinally). If during the raising or lowering process the platform becomes out of level by 2.degree.