Abstract: A hydraulic system arranged to control at least two hydraulic actuators via a metering control valve assembly. The hydraulic system is advantageous to control a pivoting arm of an undercutting mining machine according to at least two modes of operation including an idling mode and a cutting mode. In particular, the hydraulic actuators may be controlled by quantitative variation of fluid flow speed and pressure.

Abstract: In order to improve a drive arrangement (15) for valve devices (1) comprising a closing member (3), comprising a movable drive element (6) for making an operative connection with the closing member (3), pre-tensioning means for exerting a pre-tensioning force on the drive element (6) in order to hold the closing member (3) in a base position, preferably closed position, against the working forces acting on the closing member (3), and driving means (17, 21) to move the drive element (6) from the base position against the pre-tensioning force in the direction of the working forces, with a view to the disadvantages of the known drive arrangements, in particular in order to reduce the weight, it is proposed that the pre-tensioning means comprises a compressible fluid, preferably compressed air (21), enclosed in a pre-tensioning container (16), with a static pressure for producing the pre-tensioning force.

Abstract: A compressed air single-action actuator includes an actuator body, a solenoid valve is provided in the actuator body, a solenoid valve plate is provided between the actuator body and the solenoid valve, a gas chamber is provided on the side face of the actuator body, an O-ring seal is provided between the gas chamber and the actuator body; a first inlet passage communicated with the gas chamber is provided on the actuator body, a check valve is provided at one end of the gas chamber of the first gas inlet passage, the other end of the outlet is provided at a right back side of the Namur interface; a second gas inlet passage is provided on the actuator body communicated with the gas chamber, the outlet of the second gas inlet passage is provided at an upper left side of the Namur interface.

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

Abstract: The invention relates to a hydraulic control apparatus (1) for a shifting fork (7) for engaging/releasing at least one gear (G) in a manual transmission, comprising at least one shifting cylinder (2, 3) and a piston unit (6) which can move within the shifting cylinder and is connected to the shifting fork (7), and at least one control valve (8) for generating a modeled pressure which can be applied to the piston unit (6) in order to actuate the shifting fork (7). To prevent jolting when the piston unit is started up, the invention proposes a valve apparatus which provides a counter-pressure which counteracts the movement of the piston unit (6). In a preferred exemplary embodiment, a diaphragm ensures that the counter-pressure drops below the value preset by the valve apparatus at low speeds on the part of the piston unit.

Abstract: Disclosed is a flow control apparatus for construction heavy equipment capable of maintaining constant set flow rate regardless of changes in load pressure and pump pressure. The flow control apparatus is composed of a control valve, a flow control valve, and a load check valve. The control valve has a parallel passage, a housing provided with a first load passage and a second load passage, and a control spool provided to be movable in the housing. The flow control valve having a logic check valve provided to be openable between the first load passage and the parallel passage, and a logic control valve controlling a flow rate supplied to a back pressure chamber of the logic check valve. The load check valve is provided between the second load passage and the parallel passage to restrict backflow from the second hydraulic cylinder.

Abstract: Apparatus and methods are provided for pumping concrete using a pumping apparatus including first and second drive cylinders, a valve, and a pump. Fluid is delivered into the cylinders from the pump to reciprocate pistons within the cylinders. Pressure within the cylinders is monitored, and a direction of flow of the fluid is switched based upon the pressure within the cylinders. For example, during rod-side operation, the valve is set to deliver fluid into a head side of the cylinders. When the pressure exceeds a predetermined threshold, the valve switches to head-side operation, and fluid is delivered into a rod side of the cylinders. If the pressure falls below the threshold, the valve switches the cylinders back to rod-side operation.

Abstract: A hydraulic device having two hydraulic actuators, in particular a motor and a double-acting jack, each having two couplings for the entry and/or the exit of a control fluid. Two pipes are coupled to the two actuators and designed so that one conveys a pressurized fluid to a respective coupling of each actuator while the other discharges the fluid to the other respective coupling, and vice versa, in such a way that the jack can be controlled to selectively produce a movement in opposite directions. A selective reversing gate reverses, between the two pipes, the supplying of pressurized fluid and the discharging of the fluid so as to control the direction of the movement of the jack.

Abstract: A hydraulic boom control system has two valves controlling linear hydraulic actuators, one for pivoting a hoist boom relative to a machine and one for pivoting a stick boom relative to the hoist boom. The bore sides of the actuators are hydraulically connected and the rod side of the hoist actuator is connected to the first port of the first valve and to the second port of the second valve. Operating the first valve moves the boom end generally horizontally and operating the second valve moves it generally vertically.

Abstract: A hydraulic system for a utility vehicle includes provision for controlling two hydraulic implements or tools alternately with a single control lever. The hydraulic system includes a first hydraulic implement and a second hydraulic implement both hydraulically flow-connected to a diverter valve. A source of pressurized hydraulic fluid is connected to a selective control valve, operated by a control lever, and the selective control valve is hydraulically flow-connected to the diverter valve. The diverter valve is selectively operated to connect the control valve to either the first or to the second hydraulic implements. An implement-select actuator is signal-connected to the diverter valve and configured for alternately operating the first and second hydraulic implements.

Abstract: An apparatus for multiplexing a first hydraulic cylinder and a second hydraulic cylinder. Each cylinder has a head end port and a rod end port. The apparatus includes a tank, a pump connected to the tank, and a control valve having an inlet port connected to the pump, an outlet port connected to the tank, and first and second control ports. The apparatus also includes at least two two-position valves each having at least one port connected to a corresponding at least one of the first and second control ports and at least one other port connected to a corresponding one of the head end and rod end ports of the first and second hydraulic cylinders, the at least two two-position valves being operable to selectively divert hydraulic fluid from the respective first and second control ports of the control valve to one of the first and second hydraulic cylinders.

Abstract: A work attachment for a commercial work vehicle such as a skid steer loader has a unique hydraulic circuit that splits hydraulic working flow between two hydraulic functions without the need for electronic solenoids. The commercial work vehicle has hydraulic flow through two hydraulic hoses to the work attachment which can be reversed by the operator of the vehicle to provide two different hydraulic signals. During normal operation, hydraulic working output flow is directed toward a first function, such as the rotary motor of a rotary broom or rotary snow blower. To provide for the second function, the circuit includes a diversion valve that may take the form of a check valve that diverts the flow in response to one of the hydraulic signals (e.g. when flow is reversed). The diversion valve directs flow toward the second hydraulic function such as a hydraulic cylinder for positioning a portion of the attachment (e.g. to effect a selected engaging angle of a rotary broom).

Abstract: A control system for an industrial vehicle having an articulated frame with front and rear movably connected frame halves. The control system includes a steering mechanism disposed between the frame halves and is configured to pivot the rear frame half about the front frame half. A first hydraulic actuator is operably connected with the steering mechanism. An offset mechanism is disposed between the frame halves and is configured to displace the rear frame half with respect to the front frame half in a direction generally toward one of the lateral sides of the vehicle. A second hydraulic actuator is operably connected with the offset mechanism. A hydraulic circuit includes a hydraulic fluid source and a selector valve device connected with the fluid source and with each of the first and second actuators. The selector valve is configured to selectively direct hydraulic fluid to the first actuator to operate the steering mechanism and alternatively to the second actuator to operate the offset mechanism.

Abstract: A latching valve, useable in a multiplexed fluid control system, is switchable between two positions to control working output fluid flow to a corresponding actuator. The valve is latched by deriving a holding force from the working output flow. The latching valve may reside in one of the channels of the multiplexed fluid control system and eliminates the required modulations to hold position and reduces system wear of modulating and multiplexing components. The latching valve includes a working output port coupled with an associated actuator and a control chamber connected to a 3-way multiplexing valve to receive fluid signals. To provide a latching force, the valve includes bleed conduit that bleeds a controlled amount of fluid between the working output port and the control chamber to maintain the pressure in the control chamber. The last position of the latching valve is held until the next selective fluid signal from the modulating valve and multiplexer is received.

Abstract: The invention relates to a hydraulic multiposition valve, in particular a valve for selecting the steering modes of vehicles with multi-axle steering, having one or more position-seat valves (31, 33, 35, 37, 39, 41, 43), which have at least two switching positions and which communicate via lines for the hydraulic medium with one another and with a number of controlled connections (A, B, C, D; L, R) in such a manner that the desired switching positions of the multiposition valve (13) can be selected by the actuation of the seat valves (31-43); and having an actuating arrangement (29) for actuating the seat valves (31-43); the actuating arrangement (29) can be locked in detent fashion in the switching positions of the multiposition valve (13).

Abstract: Two working cylinders are provided, a pressure medium connector being secured to a first cylinder and allowing fluid to flow to and from the first cylinder through the connector. A distributor is connected to the connector and has first and second ports through which pressure medium can flow. The second port is connected to the second cylinder. The first port is connected through the connector to the first working cylinder and is also connected to the second port. The first port is connected to a source of pressure medium and when pressure medium flows to or from the first port, pressure medium also flows through the connector to or from the first working cylinder as well as to or from the second port and the second working cylinder to cause the first and second working cylinders to operate simultaneously.

Abstract: A power machine has a base, an operator support portion, and a hydraulic slew motor coupled to move the operator support portion relative to the base. A boom, an arm, and a tool are all coupled to one another and to the operator support portion and are powered by hydraulic actuators. A slew valve is coupled to receive hydraulic fluid under pressure from a hydraulic power circuit and is also coupled to the slew motor to provide hydraulic fluid to the slew motor and receive hydraulic fluid from the slew motor. A first power actuator valve is coupled to receive hydraulic fluid from the slew valve and is coupled to provide hydraulic fluid to one of the hydraulic boom actuator, the hydraulic arm actuator and the tool actuator. The slew valve is coupled in series with the power actuator valve.

Abstract: Frame sections on an implement are supported above the ground by lift wheel assemblies having positive mechanical depth stops and series connected lift cylinders. A pressure responsive bypass valve is installed in series with an orifice between the ports of the series connected cylinders. The valve permits the corresponding cylinder to be retracted and positively held against the depth stop and allows bypass flow to the next cylinder in series for continued retraction of the next cylinder until it bottoms against the stop. The orifice protects the bypass valve poppet from damaging high flows and controls the rate of descent of the other frame sections onto the remaining stops. The system permits the cylinders to positively maintain the down-stopped positions of the sections without unwanted looseness typical with slotted or other lost motion types of connections. A restrictor valve may be added to limit the maximum pressure so that all the bypass valves cannot open at the same time.

Abstract: An apparatus for controlling a first fluid cylinder and a second fluid cylinder includes an operational pressure source and a fluid control circuit. The fluid control circuit includes a pilot valve assembly having a first valve position and a second valve position. Moreover, the fluid control circuit (1) delivers pressure from the operational pressure source to the first fluid cylinder when the pilot valve assembly is positioned in the first valve position, (2) isolates the second fluid cylinder from the operational pressure source when the pilot valve assembly is positioned in the first valve position, (3) delivers pressure from the operational pressure source to the second fluid cylinder when the pilot valve assembly is positioned in the second valve position, and (4) isolates the first fluid cylinder from the operational pressure source when the pilot valve assembly is positioned in the second valve position. A method for controlling a first fluid cylinder and a second fluid cylinder is also disclosed.

Abstract: A switching valve has a control rod with a pilot chamber at each of its ends. For each pilot chamber, there is a first passageway connected to a pressure line and communicating with the pilot chamber. A second passageway is connectable to return. A relief valve has a valve member biased to close an orifice to close communication between the pilot chamber and the second passageway. The valve member has an open position in which the pilot chamber is connected to return via the second passageway to allow shifting of the control rod. In a first embodiment, the pilot chamber is continuously in communication with pressure via the first passageway, and the valve member is opened by this pressure in response to connection of the second passageway to return. In another embodiment, the second passageway is continuously in communication with return, and the valve member is mechanically moved into its open position by an operator in response to pressure acting on the operator.

Abstract: A hydraulic valve assembly configured for controlling the elevation and operation of a mowing deck of a power mower. The valve assembly includes a housing having a valve spool positionable in four positions, a cylinder activation position, a neutral position, a cylinder relief and motor start position, and a motor run position. In the cylinder activation position pump pressure is connected to a deck raising cylinder. In the neutral position, a status quo is maintained, and pump is vented to tank. In the cylinder relief and motor start position, the mowing deck, if elevated, is lowered under its own weight by relieving pressure on the deck cylinder, and the mowing motor is started in operation under low pressure. In the motor run position, the motor is connected to high pressure, and the deck cylinder continues to be vented to tank.

Abstract: A manual control valve is provided for operating at least two end users such as double acting actuating cylinders or the like either individually or simultaneously. The valve including a valve body, a distribution spool housed within the valve body and which is capable of rotation or axial displacement within the valve body by external manipulation. The valve body being connectable through an inlet to a source of pressurized fluid and through an outlet to a reservoir for exhausted fluid. At least two delivery passages spaced axially and radially on the valve body are provided for delivery of pressurized fluid to end users. The spool having distribution passages for directing pressurized fluid individually from the inlet selectability to one or the other of said delivery passages or in a second rotational position, simultaneously to both said delivery passages.

Abstract: The invention relates to a pump assembly comprising first and second pump units designed to be driven hydraulically, consisting of pump housing chambers, pump housing cylinders with pumping plungers mounted therein, and hydraulic cylinders with driving chambers which can be connected to a pressure source through a control valve for developing in the driving chambers a certain hydraulic pressure, which is used to operate the driving plungers.

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, LV5, LV6) are pulled into an open position by extension of motors (M1, M2, M3). The limit valves (LV1, LV2, LV3, LV4, LV5, LV6) include springs biasing them into closed positions.

Abstract: A hydraulic control system has first and second actuators that can be selectively moved to a second operating position dependant upon the pressure of hydraulic fluid being simultaneously transmitted thereto through a common conduit. The force of the springs of the first and second actuators is selected so that when the pressure of the hydraulic fluid is at a preselected low pressure, only one of the actuators is moved to its second position and both of the actuators is moved to their second positions when the fluid is at a preselected high pressure. The use of a common conduit for carrying fluid to the actuators eliminates the expense and complexity of providing another flow path between rotatable parts of a vehicle.

Abstract: A poppet valve device according to the present invention is adapted to sequentially operate a plurality of poppet valves the switching operation of a pilot valve, for example, an electromagnetic solenoid or the like which operates in response to an external input signal. The above-mentioned poppet valve device includes first and second poppet valves (A, B) each of which is constructed so that a poppet (32) for communicating or intercepting an inlet port (30) and an outlet port (31) with or from each other may be moved towards a communicating position by an inlet port side pressure acting upon its pressure receiving portion (32a). The poppet (32) may be moved towards an intercepting position by a pressure acting upon its back pressure chamber (38a, 38b).

Abstract: A time division multiplexed (TDM) hydraulic control system having a plurality of channels, each channel having a servo actuator. Electrical demand signals are arranged in TDM sequence and applied to a single multiplexed pilot valve so that the pilot valve produces a plurality of hydraulic signals. Commutator means are associated with the pilot valve for distributing the hydraulic signals to the associated channels. In order to achieve useful output flow rates in the channels, each channel includes a second stage valve which integrates the hydraulic signals for its channel to produce an output flow rate which is a function of the integrated signal. The flow rates are continuously produced (as compared to the multiplexed output signals) and are coupled to actuators in the channels for controllably adjusting the position thereof. Feedback means associated with the actuators includes rate feedback for stabilizing the multiplexed control loops.

Abstract: A time multiplexed hydraulic control system in which a multiple section dog valve is multiplexed among a plurality of channels. An electrical actuator on the dog valve controls pilot means. The pilot means is associated with a plurality of followers, one for each channel, and each follower controls the flow rate through an associated output port. Multiplexing means in the dog valve sequentially supplies fluid to the pilot means for sequentially positioning then locking the respective followers. Thus, each channel has continuous hydraulic flow based on the position of its dedicated follower, with the followers being repositioned on a multiplexed basis in associated time slots.

Abstract: A time division multiplexed (TDM) hydraulic control system having a plurality of channels, each channel having a servo actuator. Electrical demand signals are arranged in TDM sequence and applied to a pilot valve so that the pilot valve produces a plurality of hydraulic signals. The hydraulic signals in turn are coupled to a separate commutator which distributes the hydraulic signals to the associated channels. The pilot valve is arranged with a full annular output port to maximize the port area and thereby the flow rate to the channels. The commutator size and port area is coordinated to that of the pilot valve to minimize pressure drop across the commutator and to maximize flow rate to the channels.

Abstract: A rear wheel steering hydraulic cylinder is arranged in a rear wheel steering apparatus to steer rear wheels to the right and left. When a front wheel steering angle detected by a front wheel steering angle sensor exceeds a predetermined value, the hydraulic cylinder is actuated to steer the rear wheels in a direction opposite to that of the front wheels. When the rear wheel steering angle detected by a rear wheel steering angle sensor is changed in response to the front wheel steering angle, the hydraulic cylinder is not activated, thereby not steering the rear wheels.

Abstract: A control valve apparatus is described which is intended for selective transmission of pressure to at least two pressure spaces. A magnetic control device is provided for selectively applying a hydraulic system pressure to the respective pressure spaces. As another function, the apparatus may simultaneously depressurize the two pressure spaces through the application of a control pressure to the control valve apparatus. To minimize the required installation space and the manufacturing cost, the control valve apparatus is comprised of a single control valve, the control piston means of which can be exposed to the control pressure against the force of a restoring device and can be moved into intermediate control positions by means of the magnetic control device.

Abstract: A control head has support structure arranged to support it at the rear side of a dashboard. This control head supports a mode control lever and a valve having an elongated housing with pressure inlet and outlet laterals therein. The outlet laterals are arranged to communicate with remote fluid pressure operated structures, and the valve has a stem operated by the mode control lever for controlled operation of the inlet and outlet laterals upon pivoted movement of the lever to operate the remote fluid pressure operated structures. The structural arrangement of the control head facilitates use of quick connect and disconnect flexible tubing between the inlet and outlet laterals and with the fluid pressure operated structures. The control head also has a cam switch operated by the mode control lever for controlled operation of an air conditioning unit.

Abstract: In addition to a conventional steering system for steering a vehicle through the front wheels in accordance with an angular displacement of the steering wheel, the vehicle is equipped with a negative feedback steering control system which steers the vehicle through the front or rear wheels in accordance with an instantaneous yaw rate of the vehicle. The feedback system has a vehicle behavior sensor for sensing the yaw rate, and an control circuit which determines an actual quantity which is equal to the yaw rate or a linear combination of the yaw rate and the time derivative of the yaw rate and a reference quantity which is a function of the angular displacement and the vehicle speed, so designed as to be approximately equal to the yaw rate if there is no disturbance. The control circuit produces a feedback signal proportional to a difference between the actual quantity multiplied by a first coefficient and the reference quantity multipled by a second coefficient.

Abstract: An actuator driving system for driving a plurality of actuators operable by a fluid under pressure includes a plurality of tube joints connected respectively to the actuators for being coupled with a plurality of double-walled tubes each having a plurality of passages. Each of the tube joints includes a base member having passages communicating with respective fluid ports of one of the actuators and mounted on said one actuator, and a body member having a first cylindrical body mounted on the base member and a second cylindrical body having a hole for insertion of one of the double-walled tubes therein, to allow the passages of said one double-walled tube to communicate respectively with the passages of the base member, the first cylindrical body being angularly movable with respect to the base member.

Abstract: A hydraulic system has a rotary valve which controls multiple hydraulic dces such as double-acting piston type actuators and which prevents deactivated devices from creeping. The valve has an outer housing and a rotatable inner member which form high pressure inlet, low pressure outlet, and control stages. The control stages utilize partial commutators (part circumferential grooves) and ports on the valve member selectively to couple control ports of the housing respectively to the inlet stage or the outlet stage by rotating the inner valve member (the control ports being connected to the hydraulic devices). At the inlet and outlet stages, the valve member has full annular commutators which communicate continuously with a high pressure inlet port and a low pressure vent port of the housing as the valve member is rotated. The valve member also has internal passageways which connect each control stage partial commutator and fluid port to either the inlet commutator or the outlet commutator.

Abstract: A towveyor cart for use in hoisting an object and in particular an object having first and second interconnected portions from a first level to a fully raised level. The towveyor cart has control means which include a main control valve for simultaneously raising the jacks to an intermediate position between the lowermost position and the fully raised position and separate jogging valves for controlling each of the jacks separately between the intermediate and raised positions. In this way, both jacks can be simultaneously rapidly raised to the intermediate position and then independently jogged by the jogging valves to the final fully raised position. Horizontal adjusting means are provided so that a combination of horizontal and vertical adjustment for each jack, independent of the other jack, is obtained. Additionally, the towveyor cart is provided with an improved air reservoir which is mounted beneath the work platform of the cart as opposed to the conventional location which is on the platform.

Abstract: An automatic indexing chuck comprises a dividing pivot separately and in succession, operated by a dividing shaft and a locking sleeve. The dividing shaft is slideably and sealingly accommodated in a cavity of the locking sleeve which has retention planes for the dividing pivot and is in turn sealingly accommodated in a mandrel body cavity defining two adjacent chambers; the dividing shaft and the locking sleeve defining independent pistons operated by a single hydraulic circuit with reversible inlet and outlet ports, the pistons moving in opposite directions to perform consecutively unlocking, rotation and locking of the dividing pivot.

Abstract: Fluid control circuits commonly control actuation of a pair of cylinders for positioning an earthmoving blade. The known circuits for providing the three operating modes of the cylinders utilize a separate control valve for each cylinder thereby making precise positioning of the blade difficult since such positioning requires coordinated control of both valves. The subject fluid control circuit includes a selector valve for determining the direction of fluid flow to and from the head end and rod ends of the tilt cylinders and a single control valve for modulating and controlling the fluid flow from the pump to the cylinders. With this circuit, the selector valve can be prepositioned in the desired position prior to actuating the control valve so that dual cylinder tip, dual cylinder tilt, and single cylinder tilt of the blade is readily controlled by manipulation of only the single control valve.

Abstract: In a steering system in which both front and rear wheels are steerable, the rear road wheels are adapted to be turned in the direction opposite to the direction of turning of the front road wheels only when a steering wheel is turned with a torque or effort larger than a predetermined value.

Abstract: An automatic, hydraulically actuated, sequencing valve for use with a pair of hydraulic acutators (e.g. double acting hydraulic cylinders) includes a valve body having a cylindrical bore therein. Cam members at either end of the bore are engaged by pins on the ends of a cylindrical spool, thereby rotating the spool 30.degree. each time it engages one of the cam members. A third cam member incorporated into the spool alternately locks open one of a pair of check valves as said spool is pressure shifted between the two bore cam members. The third cam member operates a locking system which permits only one of the two hydraulic cylinders to operate at a time and in sequence.

Abstract: A boiling water reactor has a plurality of control rods disposed in the reactor and adapted to be driven independently by corresponding control rod driving mechanisms, each of the control rod driving mechanisms having a hydraulic piston adapted to be actuated by pressurized water supplied thereto through a hydraulic unit annexed to each control rod driving mechanism to drive the associated control rod into and out of the reactor core. The boiling water reactor has a system for controlling the driving water for the control rod driving mechanisms. The control rod driving water control system has a control rod driving water control unit which controls the direction and velocity of movement of the hydraulic pistons. The control rod driving water control unit is used commonly for a plurality of control rod driving mechanisms.

Abstract: For the purpose of driving a body (8) that, in order to perform a tumbling and rotating movement, is suspended by means of pivot pins (9) on two fork-shaped gimbals (5, 7) which are each connected by means of a pivot bearing (4, 6) to the end of one of two parallel drive shafts (2, 3), each of the drive shafts (2, 3) is driven by a hydraulic motor (12, 13). The two hydraulic motors (12, 13) are connected to a common hydraulic pump (14) by means of a branched line (15, 16, 17).

Abstract: A transfer switch for differential type actuators which includes a body having an internal space, a plurality of pairs of output ports connected with the internal space for supplying pressure to a plurality of differential type actuators, a flat control plate rotatable on the output ports, passages of two routes being arranged on one surface of the control plate which are connectable selectively with the plurality of output ports, input ports connected with the individual passes, and a rotary mechanism for changing over selectively the position of the control plate, whereby the function of the differential type actuator can be exerted fully and a plurality of differential type actuators can be controlled selectively and reliably.

Abstract: The invention relates to a device for controlling the supply of fluid under pressure to a hydraulic circuit as a function of the state of locking or unlocking of two mechanical members.The device comprises two interconnected jacks (1,2), the rods (3,4) of which are integrally fixed to mechanical members. The piston (30) of the first jack (1) separates the chamber (35) of the latter into two parts (35a,35b). The piston (31) of the second jack (2) divides the chamber (35') of the latter into three parts (35'a,35'band 35'c). The inlet chambers (35a and 35'a) are connected to pipes for supplying fluid under pressure (10a,10b), and the outlet chambers (35b and 35'c) are connected to a depressurizing pipe (20). According to the position of the pistons (30 and 31), which itself depends on the state of locking or unlocking of the rods (3,4), an interconnecting pipe (23) and a pipe (25) supplying the hydraulic circuit with fluid under pressure communicate with one chamber or another.

Abstract: A multiposition selector valve of the rotary type includes a valve body having a single inlet port and a plurality of outlet ports. Fluid communication between the inlet port and any one of the outlet ports is provided via a check valve assembly mounted on the valve body, and via a fluid-providing conduit connected at one end to the inlet port via the check valve. The other end of the conduit is movable in rotary fashion for fluidtight engagement with any one of a plurality of valve seat areas associated with the outlet ports. The valve seat areas are integral portions of a flat metal disk that can be removed from the valve body to facilitate maintenance of the valve. A single handle rotates the conduit through its various selected outlet positions and operates the check valve assembly to open and close the valve at selected outlet positions.

Abstract: The hydraulic control valve as described includes two precontrol valves, each of them capable of operating the valve slide element in a primary control fashion while the respective other of the precontrol valve performs auxiliary functions so that in total two sets of outputs can be controlled whereby in each case the secondary control function can be carried out persistently or intermittently for the duration of persistence of the primary control function.

Abstract: A control system for a plurality of hydraulic actuators which requires smaller number of control valves than that of actuators. In one embodiment, three control valves are arranged in parallel for controlling four hydraulic cylinders. The control valves are preferably solenoid-operated and one of control valves are used for supplying a pilot fluid pressure into a plurality of pilot-operated check valves disposed between the control valves and the hydraulic cylinders.

Abstract: A tractor hydraulic control system of the kind comprising a power lift with a hydraulic actuator (12) and a main control valve (17) controlling the supply of fluid from a pump (19) to the actuator, the system including selector valve means (50) interconnected with the main control valve (17) and movable between a first position in which flow to and from the actuator (12) occurs via the selector valve means under the control of the main control valve and the associated system control mechanism (28) and a second position in which the actuator is hydraulically locked in a given position and an external services outlet (51) is placed in communication with the pump. Linkage means (60,61,62) operatively connects the selector valve means (50) and the system control mechanism (28) to condition the main control valve (17) to cause the pump (19) to supply fluid to the external service outlet (51) via the selector valve means on movement of the selector valve means to the second position.

Abstract: A supplemental brake system operates in cooperation with a motor vehicle's extant emergency brake system for selectively slowing a spinning wheel. A selector valve communicates with the vehicle's vacuum system and conduits are sized to cause a delay in the slowing of the spinning wheel. Further, the system provides for the gradual extension of the emergency brake cables which is unaffected by changes in vacuum levels in the vacuum system. The operator has full control of the vehicle during the system's operation.

Abstract: A concrete pump comprises a pair of separate pump assemblies each having a cylinder, a piston subdividing same into a piston-side front compartment and a rod-side rear compartment, and a piston rod connected to the respective piston and extending out of the respective cylinder through the respective rod-side rear compartment. The pump also has a liquid supply having a high-pressure side and a low-pressure side for supplying liquid under high pressure at the high-pressure side and for taking in liquid at the low-pressure side.