Abstract: A pump supplies via in each case a directional valve with associated pressure balance fluid or pressure medium to a plurality of loads. When the pump power is not sufficient a proportional quantity reduction is achieved at all loads in that the control voltages of the control members for electrical actuation of the directional valves are supplied to a summation stage and the sum voltage is compared in a comparison stage with a limit value corresponding to the maximum pump displacement, whereupon when the limit value is exceeded a control signal is generated with which the stroke of the driven directional valves is reduced.

Abstract: A hydraulic valve assembly which can be used for controlling a motor or the like includes a first directional control member which selectively allows hydraulic fluid to flow from an associated hydraulic pump through a hydraulic fluid circuit to an associated reservoir and to an associated hydraulic motor. A second directional control member is connected to the fluid circuit for selectively allowing hydraulic fluid to flow directly to the associated reservoir as directed by the first member. A third directional control member is connected to the fluid circuit for selectively allowing hydraulic fluid to flow directly to the associated hydraulic motor as directed by the first member. A relief member is operatively connected with the fluid circuit for allowing hydraulic fluid to be relieved from the assembly to the associated reservoir.

Abstract: Disclosed is an air filter unit for a pressure actuator such as a vacuum actuator for a speed control of an automobile comprising a solenoid valve unit including a plurality of solenoid valves and a diaphragm unit including a diaphragm defining a pressure chamber, air pressure within the pressure chamber being adjusted by selective activation of the solenoid valves which communicate the pressure chamber with pressure sources of different pressure levels. A filter element holder defining a pair of receptacles for receiving filter elements therein is attached to the solenoid valve unit so as to intercept air flow from an external air source into the vacuum chamber by way of the solenoid valves. The filter element for a vent valve which is frequently used is finer in structure than that for a safety valve which is less frequently used and is required to be capable of rapid introduction of air into the vacuum chamber.

Abstract: A speed control actuator includes a diaphragm forming a movable wall of a variable pressure chamber. An output member is fixed to the diaphragm to impart diaphragm movement to a throttle valve of the automotive vehicle. Three solenoid valves are mounted on a common bracket and are disposed in the variable pressure chamber for controlling vacuum and atmospheric pressure into the chamber. Two of the three solenoid valves are normally biased open to assure disengagement of the actuator.

Abstract: The invention relates to a 5/3-valve, which contains two separately controllable control members which are arranged coaxially with one another in the valve housing, are movable independently of one another and each bear two sealing surfaces which in the two end positions of the relevant control member engage with an appertaining valve seat of the valve housing. Such a 5/3-valve is distinguished by a very simple construction, compactness and a long working life.

Abstract: A base means (12) for directing fluid from a pneumatic control assembly to a number of pneumatic cylinders wherein the base means (12) is remotely mounted from the pneumatic cylinder and the pneumatic control assembly is mounted to the base means (12) and is in fluid communication with the base means (12) through base ports (38,40) which extend completely through the base means (12). The base means includes an upper and lower support surface (28,30), as well as side walls (31,32) and end walls (33,34) extending therebetween, and also includes communication ports (35,36) disposed on the faces of the walls. Flow passeges provide (44,46) fluid communication between the base ports (38,40) and the communication ports (35,36) and delivery means (48) extend between the communication ports (35,36) and cylinder ports located on either side of the piston in a pneumatic cylinder.

Abstract: The apparatus disclosed herein provides controlled operation of a pneumatic actuator by effecting charging and discharging of the actuator through an intermediate step volume, the pressure in the step volume being regulated as a respective function of the existing pressure in the actuator during charging and discharging.

Abstract: An apparatus for controlling a hydraulic single acting cylinder has first and second solenoid operated valves disposed in a supply line through which a working fluid is supplied to a working chamber defined in the cylinder which a piston is disposed, a third solenoid operated valve disposed in a return line through which the working fluid returns from the working chamber to a hydraulic tank, and a control unit for controlling the first to third solenoid operated valves. The second and third solenoid operated valves are solenoid operated proportional pressure control valves so that the piston speed can be regulated.

Abstract: A control system for a hydraulic circuit having an on-off valve interposed between the control valve and the actuator for allowing and blocking a flow of hydraulic fluid therebetween in which the control valve and on-off valves are actuated and switched in accordance with an operation signal from an operation device. Pressure sensors are connected to hydraulic lines upstream and downstream of the on-off valves for detecting the pressures in these hydraulic lines, and control unit is operative to calculate, based on the pressures detected by the pressure sensors, a value which reduces the difference between thrusts applied to the actuator and output the calculated value to the control valve while the on-off valves are closed to thereby perform pressure matching control.

Abstract: A full hydraulic power steering system for a forklift truck is disclosed wherein in order to correct the position of a steering wheel in relation to an actuator for a steered wheel, hydraulic fluid is discharged from a portion of hydraulic fluid line means interconnecting a steering unit operable by the steering wheel and the actuator.

Abstract: The point at which pump out pressure exceeds load is sensed to provide a point for scheduling flow to an actuator in a hydraulic system. Flow is controlled by a stepper motor (28) that moves a flow control valve (27). The steps needed to achieve fixed flow changes are greater for high flow positions. When the pump (21) is turned on, the valve (27) is positioned to bypass flow; the bypass flow is then programmably decreased to the actuator. Reverse flow is regulated by the valve (27) to control actuator retraction. Reverse flow is initiated by opening a check valve (40) with an actuator (50) that opens it first to reduce pressure across the valve, then fully. The flow control valve (27) also operates to relieve excess pressure in the system.

Abstract: The device for controlling flow (10) situated in a branch hydraulic line (6), comprises a piston slide (15) sliding a bore (14) into which an inlet passage (36) and an outlet passage (20, 21) open, the slide forming with the outlet passage (21) a modulable restriction (s); the device comprsies a fluid passage between the inlet and outlet passages which includes a first portion (32, 33, 34), formed in the slide (15), and a second portion (19, 24, 23, 22) which is formed in the body (13) and is closed selectively by a spring biased (27) valve member (26) and the plunger (28) of an electromagnetic control member (9) piloted by an electrical signal which is a function of a significant parameter, for example the speed of a vehicle for the assisted steering of a vehicle.

Abstract: The point at which pump out pressure exceeds load is sensed to provide a point for scheduling flow to an actuator in a hydraulic system. Flow is controlled by a stepper motor (28) that moves a flow control valve (27). The steps needed to achieve fixed flow changes are greater for high flow positions. When the pump (21) is turned on, the valve (27) is positioned to bypass flow; the bypass flow is then programmably decreased to the actuator. Reverse flow is regulated by the valve (27) to control actuator retraction. Reverse flow is initiated by opening a check valve (40) with an actuator (50) that opens it first to reduce pressure across the valve, then fully. The flow control valve (27) also operates to relieve excess pressure in the system.

Abstract: An electrically operated valve assembly including a valve member maintained on a seat by a tensioned wire or filament which is heated to permit the valve member to move off of its seat. A piston and cylinder assembly including a conduit therein for permitting pressurized fluid to actuate the piston when an electrically operated valve of the type described above is actuated. A self-contained system including a reservoir, compressible liquid in the reservoir, a squib for pressurizing the compressible liquid, a piston and cylinder, a conduit between the reservoir and the cylinder, and a valve of the above-described type in the conduit for selectively admitting pressurized compressed liquid to the cylinder. A piston and cylinder system including a plurality of the above-described valve assemblies and associated conduits for selectively admitting hydraulic liquid to opposite sides of the piston to move it in opposite directions.

Abstract: A vacuum actuator having a vacuum chamber and an atmospheric chamber separated from each other by a diaphragm, and an actuator rod connected at one end to the diaphragm and extending across the atmospheric chamber to the outside of the actuator so as to be connected to an object to be actuated. At least one annular solenoid coil is mounted on the upper surface of the upper wall of the case defining the vacuum chamber, with the axis of the solenoid coil extending substantially at a right angle to the axis of the actuator rod. A plunger of the annular solenoid coil is adapted to be moved in one and the other directions along the axis of the annular solenoid coil. The end of the plunger is adapted to be moved into and out of a control pressure chamber of valve case. A port for introducing a vacuum from a vacuum passage into the control pressure chamber and a port for introducing the atmospheric pressure into the same are formed in the valve case coaxially with each other.

Abstract: The device for controlling pressure (20) situated in a branch hydraulic line, comprises a distributor slide (23) which slides in a bore (22) into which an inlet passage (27) and an outlet passage (28) open, the slide forming with the outlet passage a restriction which can be modulated selectively, the slide having an internal passage (32, 30, 29) which is provided with a restriction (30) which establishes permanent communication between the inlet passage (27) and a pilot chamber (24), a passage (36, 37) communicates with the outlet passage (28) which opens into the pilot chamber (24) through a valve seat (35) which may be closed selectively by a valve member (38) which is controlled, as a function of electrical control signals, by an electromagnetic control component comprising typically a main coil (42) and a secondary coil (45) mounted on a non-magnetic support (39) which is firmly fixed to the valve member (38).

Abstract: A hydraulic lifting and lowering system for battery-powered lift trucks includes an electronic control system which reduces or limits operator selected lifting commands in accordance with the current being drawn by an electric motor connected to drive a variable-displacement pump, and in accordance with the state-of-charge of the vehicle battery, to control a proportional valve which meters fluid flow to a lift cylinder.

Abstract: A hydraulic control arrangement for height regulation of an agricultural vehicle has a control valve with a control slider provided with a first piston portion with a control edge and a second piston portion with a throttle point. In the positions of neutral and lifting of the control slider the control edge blocks the communication from a control chamber to a working chamber which is connected with a spring chamber of a throttle valve. In the position of lifting the control edge opens and the pressure medium flows via the throttle point from the working chamber in the control chamber. Thereby the pressure in the spring chamber of the throttle valve is lifted. Therefore a lower neutral circulating pressure and a higher pressure level in the position of lifting is possible.

Abstract: A control system (10) for supplying an operational chamber (38) in an air motor with pressurized fluid causing rotors (18 and 20) therein to move and develop an output torque in response to an input signal. Electrically operated valves (52 and 54) selectively controlling the flow of fluid from first and second bellows means (48 and 50) which are normally seated to seal distribution conduit (34 and 36) connecting the operational chamber (38) to the atmosphere. A select high disc valve (104) in the fluid pressure supply passage provides operating fluid to the distribution conduit (34 or 36) opposite the one which is vented to the atmosphere. In a two position air motor powered actuator, the electrical signals for the valves (52 and 54) may be derived as a simple function of actual rotor rotation and rotor rotational speed.

Abstract: A hydraulic servo actuator has an outer case, a rotatable shaft extending through the case, an input sleeve rotatably mounted on the shaft and having hydraulic fluid supply and discharge passages therein and having surface grooves communicating with the passages, an output member on the shaft and movably abutting the input sleeve and having fluid supply and discharge passages therein and having surface grooves communicating with the passages and being opposed to corresponding grooves on the input sleeve, the outer casing and the output member defining an actuating chamber therebetween into which the passages in the output member open; the actuating chamber is shaped for causing the output member and the outer case to rotate relatively and rotate the shaft and case relatively when fluid supplied into the chamber from the passages under control of relatively rotation of the input and output members creates an unbalanced pressure on parts of the actuating chamber.

Abstract: (a) Hydraulic servo motor comprising a jack (1, 14) intended to be connected by its rod (3.sub.1, 3.sub.2, 15.sub.1) to a moving member to be displaced and accurately positioned, said jack being completely filled with liquid;(b) Servo motor characterized in that the displacement of the piston (2) is implemented by direct liquid transfer from one chamber to the other chamber of the jack by at least one electric vibrator pump (6) supplied by an alternating current power source and in that a so-called electro valve (7), normally open when not in operation, is connected in order to make the two jack chambers communicate;(c) The invention relates to hydraulic servo motors.

Abstract: A brake booster can switch operating mode from a positive-pressure mode using a signal-controlled fluid pressure supplier to a vacuum-pressure mode and vice versa. The booster includes a booster converter holding both an air valve and a vacuum valve of the booster closed in the positive-pressure mode or holding the booster air valve in its closed and open positions while holding the booster vacuum valve in its open and closed positions respectively when the brake pedal is released and depressed in the vacuum mode. The fluid pressure supplier is enabled while both booster valves are in the closed position in the positive-pressure mode.

Abstract: The hydraulic system of this invention is for operating a tree processing implement on a work vehicle so that during a first part of an operating cycle the implement is supplied by two hydraulic pumps jointly, while during another part of the operating cycle the implement is supplied by only one of the pumps. The result is that during the first part of the cycle the implement moves rapidly but during the other part it moves slowly.

Abstract: A linear servoactuator including an integrated split-secondary differential transformer position sensor and a fluid driven linear actuator controlled by solenoid poppet valves. Signals from the position sensor transformer are digitized and linearized by a control microcomputer by using digitized transformer signals as addresses for a programmable read only memory. The linearized output is compared to a command position to determine an error value. When the error reaches a predetermined magnitude, indicating that the actuator is approaching the command position, solenoid poppet valves are actuated by a pulse-width modulated signal from the microcomputer to progressively decrease the fluid flow to the actuator for deceleration.

Abstract: An electrohydraulic compact drive for turbomachine valves includes: a device for supplying electric power, receiving electrical addressing signals and converting the signals into positioning and control variables; an hydraulic supply system including a fluid tank, pump, motor, accumulator and manifold; an hydraulic power piston/cylinder system including a piston rod connected to a valve, and a spring biasing the piston; an electrohydraulic addressing system generating a pressurized fluid flow opening the valve spindle against the spring dependent upon the variables; control members of the addressing system, the power system and the supply system forming a compact drive block at a valve; the pump being switched as a function of a pressure limit by intermittent charging and discharging operations between the charging pressures; the pump charging the accumulator in charging operation until the upper pressure is reached and, after being switched, returning the fluid to the tank in substantially pressureless circu

Abstract: A system and method for pulse-width modulation of multiple solenoid-operated valves in an electrohydraulic servo system employing a microprocessor-based digital controller. Solenoid-energization pulse widths are identified by comparison of operator command input signals to feedback signals responsive to actual motion at the actuators and loads. During each modulation period, all solenoids are initially selectively simultaneously energized as a function of binary information stored in an energization control register, and the shortest energization pulse duration is identified. After a delay corresponding to such shortest duration, during which the microprocessor may perform other control functions, the solenoids associated with such shortest duration are selectively de-energized as a function of binary information stored in a de-energization control register.

Abstract: A pilot operated relief valve has a main relief valve (10) and a pilot relief valve (31) connected between a control chamber (23) and drain. A restriction (16) connects the control chamber (23) to the inlet chamber (22) which is separated from the control chamber by a piston (24) integral with the main relief valve closure member (12). Thus opening of the pilot relief valve against the adjustable force of a spring (14) determines the maximum pressure in the inlet chamber (22). The control chamber (23) can also be connected to drain (70) by a pilot valve (19) which is operated by a force motor (52) against pressure in a feedback chamber (56) connected to the inlet passage (22). The energization of the force motor (52) can be adjusted to adjust the relief pressure to a value below that at which the pilot relief valve (31) opens. Alternatively the pressure in the feedback chamber (56) can depend on the pressure at at least one side of a load fed via a directional valve from the inlet passage (22).

Abstract: A cylinder driving apparatus, wherein a head chamber and a rod chamber of a cylinder for driving a load upwardly and downwardly are communicated with a pressure accumulation tank by way of a balance pipeway equipped with an electromagnetic proportional flow control valve and a recycling pipeway equipped with a pressure control valve mechanism, respectively, and the load is driven by feeding air at reduced pressure to the rod chamber or discharging it to the external atmosphere by way of the pressure control valve mechanism while applying air pressure into the head chamber of the cylinder against the load by way of the electromagnetic proportional flow control valve for adjusting the driving speed.

Abstract: A valve assembly for controlling fluid flow between a fluid source and a load has an intake valve having a valve body displaceable between a closed position preventing flow through the intake valve and an open position permitting such flow and an output valve having a valve body displaceable between a closed position preventing flow through the output valve and an open position permitting such flow. Conduits or passages connect the valves in series between the load and the source so that fluid can only flow between the load and source when both of the valves are in their open positions. Respective biasing units urge each of the valves into one of its positions and respective electromagnet-type actuators are electrically energizable to move each valve into the other of its positions. The one position of one of the valves is the closed position and the one position of the other valve is the open position. In addition the two valves are substantially identical.

Abstract: A hydraulic system in which a pilot operated hydraulic four-way main valve (11) controls the direction and rate of fluid flow to a hydraulic load (13), includes a flow sensor (15) which is capable of operating bidirectionally and may therefore be located in one of the service lines (25, 26) from the main valve (11) to the load (13). The main components of the flow sensor are a variable or fixed aperture flow sensing orifice (52, 53), and a pressure transducer (18) to which the pressure differential developed across the orifice is applied and which converts the pressure differential into an electric negative feedback signal. This electric feedback signal is compared in an electronic circuit (17) with a demand signal, and a corresponding command signal sets the pilot valve (12) which controls the main valve (11).

Abstract: A servo valve comprising a source pressure valve whose inlet port receives a source pressure and whose outlet port communicates with the output of the servo valve, a pressure relief valve, which may operate independently from the source pressure valve, whose inlet port communicates with the outlet port of the source pressure valve and whose outlet port communicates with a pressure sink, for instance the atmosphere, and an electric circuit which controls both the source pressure valve and the pressure relief valve in such a manner that their actions are cooperative in a certain way. Since the source pressure valve and the pressure relief valves are not linked to each other by any mechanical means, the servo valve is very simple in its mechanical structure, fast in response, and does not require subtle mechanical adjustment.

Abstract: An air pressure control system for use where a plurality of various sequential and repetitive air pressures are selectively required. A pilot air operated pressure regulator valve having a pilot air operator and a working air flow control valve are connected in series in a pressurized working air conduit between a source of pressurized air and an air cylinder. A pilot air pressure selector circuit means, for selectively and sequentially providing a plurality of pre-set pilot air pressures to the pilot air operator of the pilot air operated pressure regulator valve, includes a plurality of pressurized pilot air conduit means which are connected in parallel with each other, and with one end of each pressurized pilot air conduit means being operatively connected to the source of pressurized air and the other end thereof being operatively connected to the pilot air operator of the pilot air operated pressure regulator valve.

Abstract: An electrohydraulic servovalve which includes as an integral part thereof a monitor valve which senses the absence or lack of system pressure in the first or second stages of the valve and translates in the absence thereof to deactivate load control. The torque motor of the electrohydraulic servovalve is biased, electrically or magnetically, to provide a failure indication in the first stage of the valve in the absence of or excess of applied electrical signals to the torque motor.

Abstract: A digital proportional valve with valve spool driven in discrete steps by a digital spool actuator in response to a remote manual control signal, while the proportional valve may be provided with positive and negative load compensation.

Abstract: A hydraulic actuator assembly for a push-type die closing unit of an injection molding machine which has a central, internally bypassable power piston, lateral cylinders for rapid opening travel and a rearward stationary plunger for rapid closing travel, the lateral travel cylinders and the pressure spaces of the power cylinder creating a differential effect under which a small external flow volume of pressurized fluid is required from the pump to produce rapid opening and closing travel while a much larger internal flow volume passes through a flow connection between the cylinders. A program-controlled proportional-response throttle valve in this flow connection gives an accurate and steady control over the travel speeds, especially during deceleration. The throttle valve also makes it possible to obtain a forcible initial die opening movement.

Abstract: A hydrostatic or pneumatic drive for driving a mass to be accelerated and decelerated, such as in a die casting or injection moulding machine, has a controllable valve arrangement which is operable to vary the fluid flow rate therethrough. The fluid flow rate is controlled by a reference value control generator operable to produce a ramp having superimposed thereon further control pulses. Such control pulses are a positive control pulse at the beginning of the rising slope and at the end of the falling slope of the ramp and a negative control pulse at the end of the rising slope and at the beginning of the falling slope of the ramp. Each control pulse has a volume which corresponds to a so-called compression volume factor which reflects the compressibility of the fluid used in the drive and also of the elasticity of ducts which expand by fluid pressure.

Abstract: The invention relates to a pneumatic setting device having oppositely operable magnetic valves for alternately pressurizing and exhausting expansible chambers formed by one or more diaphragms to which a reciprocatable setting element is attached. In this construction a return spring may be omitted.

Abstract: A device of this nature incorporates at least one control piston displaceable within a casing, the casing having at least one venting nozzle authorizing the insertion of the piston into one of its possible operating positions, which nozzle may be shut off by means of an electromagnetically operated closing device for preparation of the outward displacement of the piston out of this operating position. To accomplish that such devices may manage with a substantially reduced electrical battery power for their electromagnetic closing device, a permanent magnet is provided which co-operates with a ferromagnetic member of the closing device, in such manner that the closing device continues to be held in its closing position while the control piston is being reversed, although the supply of electrical power to the closing device had already been turned off.

Abstract: An actuator for controlling the pressure in an internal space defined by a spring-biased diaphragm and a housing by solenoid valve. The internal space is selectively communicated with a negative pressure port or an atmospheric pressure port through a first solenoid valve. The pressure in the internal space is determined by the ratio of a time period in which it is communicated with the negative pressure port to a time period in which it is communicated with the atmospheric pressure port, and the position of the diaphragm is determined accordingly. Another solenoid valve for releasing negative pressure is included for safety. To the housing fixed are a microcomputer for receiving status signals from a vehicle speed sensor, clutch ON/OFF sensor, brake ON/OFF sensor, etc. to generate a solenoid valve opening and closing signal, and a printed board incorporating an electrical driver adapted to energize the solenoid valve in response to said signal.

Abstract: A continuously variable transmission (2) is constructed utilizing a constant displacement pump (4) of fixed fluid power stroke, rather than a variable displacement pump with a variable pump stroke. A fluid motor (14) is driven by the pump and has an output stroke. Means (22) are provided for varying the output stroke without varying the input power stroke.

Abstract: A fluid servo actuator control/damping mechanism and method which utilize and combine the functions of an electro-mechanically driven servo valve to achieve ram or actuator fluid flow and load control even after loss of fluid power as well as the main ram position control function under normal operating conditions.

Abstract: A pushbutton control system for raising and lowering the dump body of a dump vehicle. Included are "up", "hold" and "down/float" switches which are connected in circuit with "up", "down" and "float" solenoid valves. These valves on energization direct pressurized air into the "up", "down" and "float" chambers of two air cylinders included in an actuating mechanism for a hoist valve controlling the telescopic hoist cylinders of the vehicle. The dump body is raised upon depression of the "up" switch with the consequent opening of the "up" valve. The depression of the "down/float" switch, resulting in the opening of the "down" valve, causes the dump body to lower by the forced contraction of the hoist cylinders. Upon subsequent release of the "down/float" switch the "float" valve opens to allow the dump body to lower under its own weight. The depression of the "hold" switch, with the consequent closure of all the solenoid valves, makes it possible to hold the dump body against movement in any desired position.

Abstract: The slide (61) of an electrohydraulic valve (31) delimits two end chambers (57, 58) respectively fed by a control pressure that is a slave to the open or closed state of one of the two solenoid valves (51, 52) controlled by signals processed by an electronic control (50) and the establishment of a state acts on the slide (61) in direction of a throttling of the delivery which causes a feed channel of the valve (31) and a working line (27, 28) from a pump (1) to communicate with the line (70) for connection with the fluid tank (2).

Abstract: A first front face of a main control spool of a main control valve is loaded with a constant pressure, whereas the opposite face is loaded with a controlled pressure to control the fluid passages to and from a hydraulic actuator. The control pressure is adjusted by means of a two-edge control of the pilot control spool of a pilot control valve which is actuated by a single proportional solenoid against the force of a spring. The advantages obtained thereby result in a substantial savings in manufacturing expenditure and a substantially improved control operation.

Abstract: An electro dynamic set device including an output set element, a piston having a piston rod and operable against the action of a force of hydraulic pressure and means defining a valve passage which communicates with an operating side of the piston to which hydraulic pressure is supplied. The passage is opened and closed by a control slide which operates by an electromagnet that can apply a magnetic force. A spring acts between the control slide and the piston such that the spring tends to move the control slide against the action of the magnetic force in a direction closing the passage. The control slide is annular and concentric around the piston rod and is located together with a coil of the electromagnet and an associated armature thereof in a common chamber. The coil encircles the piston rod as does the slide. The operating side of the piston is in the common chamber, the armature being suspended by another spring which permits movement of the armature in the length direction of the control slide.

Abstract: A control arrangement for a hydraulic motor has an adjustable pressure medium supply device with a container, an unblockable check valve with a control connection, a plurality of chambers including a supply chamber, a motor chamber, first and second return chambers, and a control chamber, a control slider displaceable relative to the chambers, wherein a control conduit extends from the supply device and leads to the control chamber, a first pressure control member is arranged on the control slider so that in a lowered position of the latter the first pressure controlling member is located between the control chamber and the second return chamber and the control slider in its raised position blocks the control chamber, and a second pressure controlling member located between the control chamber and the motor chamber and opening into the latter.

Abstract: A vacuum responsive switch for detecting a failure in creation of a control vacuum within the control diaphragm chamber. A solenoid valve is provided which functions to equalize pressure within one of a power diaphragm chamber and a leak chamber with the other when vacuum represented by a signal from the vacuum responsive switch is lower than a predetermined value.

Abstract: A pressure regulator includes an inlet adapted to be connected to a pressure source and a chamber in which the pressure is to be regulated. An orifice is provided between the inlet and the chamber for metering the flow of hydraulic fluid therebetween. In addition, regulating means is provided adjacent the orifice and is movable in a timed relation in response to a series of pulse signals for changing the effective flow area of said orifice whereby the pressure in the chamber varies with the integral of the voltage pulses.

Abstract: A pneumatic door control equipped with a door control valve for operating a door drive to an open or a closed position. The door control valve has an opening and a closing solenoid-operated pilot valve and an opening and closing spool valve, each operable to a passage or a vent position. A shuttle valve is part of the control valve and works in conjunction with an operator-controlled emergency valve to vent both spool valves simultaneously. A differential pressure switch is connected to the door drive to sense abnormal pressure expended in a door-opening or closing movement. Such an occurrence will output a signal to an electronic switching device which also monitors, via limit switches, whether a door is fully opened or fully closed. If excess pressure occurs during a door-closing movement, the switching device will trigger the control valve to reverse to the opening position.

Abstract: Container handlers comprise a plurality of double-acting hydraulic cylinders to effect the various side shift, twist lock, tilt, height adjustment, and spread modes of operation. Separate control valves and hoses, entrained over the mast assembly having the attachment thereon, are required to effect such functions selectively. This invention is directed to a programmed electro-hydraulic control circuit when reduces the required number of hoses to two and provides a non-complex system which can be operated expeditiously.