Abstract: A work vehicle (2) having an implement position controller (50). Set elevations and orientations of the work implement (5) can be preselected and changed. The controller (50) automatically positions the implement (5) in the desired elevation and orientation. Means (51) for preventing the work implement (5) from falling into the ground are also provided.

Abstract: A control valve is disclosed for use in controlling flow of hydraulic fluid from a hydraulic pump to a plurality of actuators. The control valve includes a valve housing within which are formed control bores, pressure-compensating bores, a feed passage communicating between the pressure-compensating bores, a selected-load pressure transmitting passage communicating between the pressure-compensating bores, a pair of return passages communicating between the control bores and a reservoir tank, control passages communicating respectively between each of the control bores and each of the pressure-compensating bores, and feeding and exhausting passages, as well as actuator ports, communicating between the control bores and the actuators. Control valve spools are slidably mounted, respectively, in the control bores, and pressure-compensating valves are slidably mounted, respectively, the pressure-compensating bores.

Abstract: A hydraulic control system for driving a plurality of actuators basically includes directional control valves, and pressure compensation valves, and at least one detection valve, the directional valves and the pressure compensation valves both corresponding in number to the actuators. These valves are mounted or incorporated in a body. The body has a plurality of regions corresponding in number to the actuators. Each of the regions of the body has a first hole, and a second hole substantially perpendicularly intersecting the first hole. A load pressure chamber for receiving a load pressure of the corresponding actuator is formed at the intersection between the first and second holes of each region. A spool of the directional control valve is received in the first hole. A balance piston of the pressure compensation valve is received in that portion of the second hole disposed on one side of the load pressure chamber.

Abstract: A hydraulic drive system for a crawler-mounted construction vehicle includes: a hydraulic pump (1); a plurality of hydraulic actuators including traveling hydraulic motors (2, 3) driven by the hydraulic pump; a plurality of flow control valve means including first and second flow control valve means (15, 16; 35, 36) for respectively controlling the flow rates of the hydraulic fluid supplied from the pump to motors; pump controlling means (11) for effecting control during the driving of the motors in such a manner that the discharge pressure of the pump becomes higher by a fixed value than the higher one of load pressures of the motors; and first and second pressure balance valve means (17, 18; 37, 38) for respectively controlling the rates of flow through the flow control valve means during the driving of the motors in such a manner that the load pressures of the motors do not affect the rates of flow through the first and second flow control valve means.

Abstract: Control system for a load-sensing hydraulic drive circuit comprising; at least one hydraulic pump; hydraulic actuators driven by the hydraulic pump; and a pressure compensated flow control valve between the pump and each of the actuators, for controlling a flow rate of fluid to each actuator in response to a control signal. The control system has first detection means for detecting a differential pressure between the pump delivery pressure and the maximum load pressure; second detection means for detecting the pump delivery pressure; first means for calculating a differential pressure target pump delivery amount Q.DELTA.p to hold the differential pressure constant; second means for calculating an input limiting target pump delivery amount QT based on at least a pressure signal from the second detection means and an input limiting pump function; third means for selecting one of the differential pressure target delivery amount Q.DELTA.

Abstract: A hydraulic drive system has first and second flow control valves. Each of the control valves has a main valve of the seat valve type with a valve body for controlling communication between an inlet port and an outlet port which are both connected to a main circuit. Each further have a variable restrictor capable of changing an opening degree thereof in response to displacements of the valve body, and a back pressure chamber communcating with the inlet port through the variable restrictor and producing a control pressure to urge the valve body in the valve-closing direction. A pilot valve is connected to a pilot circuit which is connected between the back pressure chamber and the outlet port of the main valve; and an auxiliary valve is connected to the pilot circuit for controlling a differential pressure between the inlet pressure and the outlet pressure of the pilot valve.

Abstract: In a hydraulic drive system, first and second flow control valves means comprise each: a main valve having a valve body for controlling communication between an inlet port and an outlet port both connected to a main circuit, a variable restrictor capable of changing an opening degree thereof in response to displacements of the valve body, and a back pressure chamber communicating with the outlet port through the variable restrictor and producing a control pressure to urge the valve body in the valve-opening direction; a pilot valve connected to a pilot circuit which is connected between the inlet port of and the back pressure chamber of the main valve; and an auxiliary valve connected to the pilot circuit for controlling a differential pressure between the inlet pressure and the outlet pressure of the pilot valve.

Abstract: A hydrostatic drive assembly with an adjustable pump driven by a primary power source, which acts on several consumers of hydrostatic energy, is disclosed which has a control and regulating device with nominal speed value pickups and adjustable restrictors for each consumer. In order to obtain a control and regulating device at a low production cost, one that operates with a low power loss, it is proposed that the nominal speed value pickup send an electric signal to an electronic control device, that each consumer be provided with an actual speed value pickup, which the control device, and the restrictors assigned to each of the consumers in their connection lines are designed as electromagnetic throttle valves controlled by the electronic control device.

Abstract: A vehicle stabilizer apparatus having a plurality of hydraulic stabilizer actuators with each actuator having an integral isolation valve effective to enable operation of a sequentially operable device such as a boom cylinder only after ground-engaging feet associated with the actuators have been brought into firm contact with the ground or other supporting surface. Each actuator is mounted for bodily movement between upper and lower positions on an associated vehicle supported mounting pin. The actuator is caused to move to its upper position when the associated ground-engaging foot engages the ground and through a plunger and plunger spring associated with the isolation valve the position of the actuator is sensed. The isolation valve is in a hydraulic circuit to prevent operation of the boom cylinder unless the actuator is in its upper position.

Abstract: According to the parent patent on inadequate power of the delivery pump the flow rate set at the directional control valves for the consumers is reduced in equal proportions in that electrical signals proportional to the flow rates 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 delivery flow. When the limit value is exceeded a control signal is generated with which the stroke of all the driven directional control valves can be jointly reduced. According to the application of addition the signal voltage supplied to the summation stages and corresponding to the respective flow rate can be obtained in a displacement pickup associated with each directional control valve or in a pressure pickup measuring the pilot pressure if the directional control valves are not controlled electrically but hydraulically.

Abstract: A pump supplies a plurality of consumers each via a directional control valve with pressure balance. When the pump delivery is not adequate, manifesting itself in a dropping of the pump pressure, the pressure balance of the consumer with the highest load pressure is displaced out of the end position of its regulating position into a further control position in which a control pressure line is connected via a throttle point to a discharge so that by means of the throttle point a control pressure is generated which is used for equiproportional reduction of the supply flow to the consumers. This is done either by reducing the stroke of the directional control valves or by acting on the pressure balances in the closure direction.

Abstract: A self-propelled concrete cutting saw in which the saw and self-propelled platform associated with the saw are both driven by hydraulic motors, with separate motors for each of the two propelling wheels so that the device may be steered by varying the speed of either of the wheels, with the speed of longitudinal movement of the saw through the concrete being controlled by the density of the concrete being cut by the saw so that the saw blade is operated at an optimum rotational speed.

Abstract: A road finishing machine comprising a diesel-hydraulically driven set of main wheels and at least one set of steerable wheels. An additional hydraulic companent is provided which transfers a driving force to the steerable wheels, and the peripheral speed of the steerable wheels is automatically adapted to that of the main wheels.

Abstract: A large industrial earthmoving machine having a hydraulic propulsion system comprising at least two hydraulic motors which are powered from a source of hydraulic fluid to drive a common load. Each motor of the hydraulic propulsion system is provided with two compensating valve assemblies. Each compensating valve assembly is provided with a compensating spool and a shuttle spool to provide accurate control of the hydraulic motors. In each pair of compensating valve assemblies, there is a forward compensating valve assembly and a backward valve assembly respectively controlling forward and backward movement of the hydraulic motor. Between the both forward compensating valve assemblies and the respective hydraulic motors, the compensating valve assemblies are fluidically coupled to one another by a small hydraulic communication line that better equalizes hydraulic fluid flow to the motors and prevents domination of one forward compensating valve assembly over the other.

Abstract: A drive system having two hydrostatic gears (1, 2) driven by a common driving motor or by a plurality of driving motors having a fixed speed ratio, each having a pump (5, 6) and a hydraulic motor (7, 8) and in which the delivery or intake volume setting of the pumps (5, 6) and/or the hydraulic motors (7, 8) is performed by hydraulic servomechanisms (13, 14) of which the control pressures in the control pressure lines (23, 24) can be varied as desired either independently or together by means of pressure indicating valves (26) connected to each of the gears (1, 2) and supplied by an auxiliary source of pressure (9, 10) is arranged so that, at least on starting, the outputs of the gears (1, 2) are as nearly as possible equal.

Abstract: The drive motor (1) drives a machining tool (2) which can be fed forwardly by means of a feed motor (3). Both motors (1, 3) are supplied with pressure fluid by the same hydraulic pump (4). A quantitative divider valve (5) divides the oil flow coming from the hydraulic pump, a control valve (24) controlling the flow of pressure fluid in the forward feed motor in such a way that the power output at the forward feed motor falls with increasing resistance at the machining tool, thereby providing for output-regulated operation of the machining tool. In the same way as the forward feed movement, the feed movement in respect of depth of the machining tool can also be produced by way of a depth feed motor (7).

Abstract: A power steering assembly for a large vehicle including a primary booster, an auxiliary booster, a primary hydraulic oil pipe adapted to connect the primary booster to the hydraulic pump, an auxiliary hydraulic oil pipe branched off from the primary hydraulic oil pipe and adapted to connect the auxiliary booster to the hydraulic pump, a control valve provided to the primary hydraulic oil pipe at an upper stream side from the place where the auxiliary hydraulic oil pipe is branched off, and a load sensing valve provided to the auxiliary hydraulic oil pipe. When the load of the primary booster is small, the oil pressure of the primary booster is low, the load sensing valve is closed, and only the primary booster is driven, whereas when the load of the primary booster becomes large, the oil pressure of the primary booster is high, the load sensing valve opened, and the auxiliary booster is driven in association with the primary booster to supplement the steering power of the primary booster.

Abstract: A self-propelled concrete cutting saw in which the saw and the self-propelled platform associated with the saw are both driven by hydraulic motors, with the speed of longitudinal movement of the saw through the concrete being controlled by the density of the concrete being cut by the saw so that the saw blade is operated at an optimum rotational speed.

Abstract: A plurality of mechanically coupled secondarily controlled hydrostatic machines with variable volume are connected to a line with impressed system pressure fed by a primary unit. By reducing the variable volume to 0 in individual hydrostatic machines the remaining machines are subjected to a higher torque which results in a greater pivot angle of the remaining secondary units. As a result the efficiency and controllability are improved. The changeover is effected in dependence upon an upper and lower switching point corresponding to the pivot angle of the unit remaining in engagement.

Abstract: A pump supplies via in each case a directional valve a plurality of consumers with fluid, a pressure balance for load-independent division of the pump displacement being provided between each branch line branching off the pump delivery line and the directional valve. In a pressure regulating valve common to all pressure balances a control pressure is generated from the pressure difference between the pump pressure and the respective highest consumer pressure and is applied to all the pressure balances so that when the pump power is inadequate a proportional quantity reduction at all consumers is achieved.

Abstract: A dual pressure source, or selectively alternative high pressure source, control system for a variable displacement hydraulic unit servo mechanism wherein normal control of the unit is provided by the low pressure source, such as a transmission charge pump, and wherein a high pressure source of control fluid with a restrictive orifice is provided to initiate servo movement, especially under conditions generating high internal friction. The flow restrictive orifice generates a pressure drop in a high pressure control line once the servo mechanism starts to move, inducing flow through such line. Thus, the control system provides a momentary source of high pressure fluid but permits control rate changes which are substantially independent of the hydraulic unit working pressure. Preferably, the high pressure source is a shuttle selected highest pressure of a transmission main loop incorporating the hydraulic unit.

Abstract: A hydraulic drive system for counterweight dolly in a counterbalance type crane, including dolly driving wheels supported vertically movably through wheel supporting hydraulic cylinders at the lower portion of the counterweight dolly which is connected to the rear portion of a crane body; a wheel driving hydraulic motor connected to each of the wheels; a support pressure detecting mechanism for detecting a support pressure for each wheel supporting hydraulic cylinder, the support pressure detecting mechanism being provided in a drive circuit for the cylinder; and a mechanism for controlling the driving pressure for the wheel driving hydraulic motor in accordance with a detected value provided from the detecting mechanism.

Abstract: A hydraulic drive system for a counterweight dolly in a counterbalance type crane having a crane body provided with a lower travelling structure an upper swivelling structure and the counterweight dolly connected to the rear portion of the upper swivelling structure through a connecting member, characterized by including a swivelling hydraulic motor for swivelling the upper swivelling structure of the crane body; a swivelling control valve for controlling the pressure of hydraulic oil to be fed to the swivelling hydraulic motor; a hydraulic circuit for swivelling operation which controls the amount of operation of the swivelling control valve; a hydraulic motor for the counterweight dolly which drives each wheel of the dolly; a dolly control valve for controlling the pressure of hydraulic oil to be fed to the hydraulic motor for the counterweight dolly; and a control circuit for actuating the dolly control valve in accordance with an operational pressure of the hydraulic circuit for swivelling operation and t

Abstract: A control system is provided for a hydraulic actuating system having a multi-phase stepping motor with a driver therefor which supplies and controls DC current through each of the motor windings such that no current is induced into the control winding from adjacent windings. The stepping motor precisely controls the rotation of an eccentric cam engaging an actuating plunger which actuates a control valve of the hydraulic actuating system. The driver receives control signals from a computer programmed to calculate, from user input command signals indicative of the desired system condition, and generate those control signals which most quickly achieve a rough approximation of the desired system condition. After this rough approximation is attained, the computer generates new control signals for the driver as a function of feedback signals and/or system component characteristics so as to precisely achieve the desired system condition.

Abstract: There is provided a vehicular speed responsive power steering device. The power steering device comprises a main pump unit adapted to supply oil under pressure through a control valve to an actuator to thereby assist steering force. The main pump unit comprises a vehicular speed responsive pump having the suction port connected to an oil passage extending between the discharge port of the main pump unit and the control valve and a reaction mechanism for controlling the operation of the control valve.

Abstract: A hydraulic control system for a downhole sidewall coring tool having first and second power hydraulic systems in which changes in pressure drop in a portion of the first hydraulic system adjusts a control valve to change the pressure in a part of the second hydraulic system. Means are provided to adjust the operation of the control valve as a function of viscosity change in the hydraulic fluid caused by change in ambient temperature.

Abstract: A retractable in-row tiller device is adapted for mounting on a movable vehicle and for tilling the ground around and between objects in a row. An outrigger arm with a rotary tiller mounted on its distal end is retracted inwardly and extended outwardly by a trapeze-type control arm which amplifies the velocity and magnitude of reciprocal motion produced by a hydraulic ram to move around and avoid objects encountered in the row. Both manually and automatically operable controls are included respectively to allow an operator to retract and extend the tiller out of and into the row as desired and to cause the tiller to be retracted and extended out of and into the row automatically upon encountering an object in the row. Manual control is also provided for the operator to override the automatic retraction control.

Abstract: A control having a primary work system, a secondary work system, a first fluid flow generating system, and a second fluid flow generating system is provided. A control signal delivering device is provided to deliver a control signal having a magnitude responsive to a relative location of a control valve between a first and second position of a control valve. A control signal receiving device receives the control signal and separately controls the flow rate deliverable from the first and second flow generating system in response to the magnitude of the control signal received. The control signal receiving device has a set point value which is representative of a preselected magnitude of the received control signal. The second fluid flow generating system is controlled to deliver fluid only in response to the magnitude of the received control signal having a value greater than preselected deliverable flow rate.

Abstract: This invention concerns a motorizing device for a vehicle, of the trailer category which is attached to a tractor equipped with a main engine organ. In particular, placed on said vehicle, the device includes: an auxiliary thermal engine (20), a plurality of hydraulic engines (50) respectively associated to each drive wheel of the trailer, an equal number of pumps (31) respectively connected to hydraulic engines (50) and associated to the auxiliary thermal engine. The device includes in addition a regulating element (100) which acts either on the hydraulic engines (50), or on the pumps (31), which is sensitive to the rotating speed of the main engine organ of the tractor.

Abstract: A hydrostatic drive arrangement for a vehicle providing synchronized rotation of a pair of output drive shafts including a pair of transmissions each having a closed loop hydraulic circuit hydraulically interconnecting a variable displacement pump and a hydraulic motor, and a pressure responsive hydraulic synchronizing valve disposed between the hydraulic circuits and normally open to permit interflow of fluid between the hydraulic circuits with the valve being responsive to fluid pressure in one of the hydraulic circuits to restrict flow therethrough when the fluid pressure in the one hydraulic circuit exceeds a predetermined value.

Abstract: A pallet truck hydraulic jack has a base plate mounting a lift cylinder with a reciprocal piston or lift rod and a pump cylinder with a reciprocal pump piston. A cartridge type directional control valve assembly within the base plate controls the flow of pressurized hydraulic fluid in respective manifold passages so that manual actuation of the pump effects a quick lift of the frame when it is unloaded, effects an additional application of lifting force through the lift cylinder when the frame is loaded, bypasses pressurized hydraulic fluid to the reservoir when the frame is overloaded, and provides a release of pressurized hydraulic fluid from the pump cylinder and the lift plunger and returns it to the reservoir for lowering the frame and forks.

Abstract: A system for limiting the torque of a multiple hydraulic system power drive unit wherein plural hydraulic motors are connected to a common torque-summing output device. The system has at least two separate hydraulic circuits, with there being a pressure-limiting valve in each circuit which controls the porting of motor pressure to a low pressure return line and which sums the motor pressure existing in the fluid circuit in which the valve is positioned and the pressure in the other hydraulic circuit whereby the maximum pressure of the fluid delivered to the motor cannot exceed one-half the maximum pressure when both circuits are active to limit the torque applied to the torque-summing output device.

Abstract: Control arrangement for regulating the speed of movement of a hydrostatic energy consumer is provided in which the ratio between pressure supplied and power on the output side is constant, in particular, a piston capable of sliding in a cylinder connected to a pressure main line, characterized in that an initial hydrostatic displacement machine is connected between the pressure main line and the consumer and is coupled with a second hydrostatic displacement machine on the shaft side, the second hydrostatic displacement machine is adjustable with respect to its displacement volume per revolution and is connected on the one hand to the pressure main line and on the other hand to a chamber carrying a lower pressure, where the adjusting element of this second displacement machine is connected with an r.p.m.-regulating device.

Abstract: A hydraulic transmission system for tracked vehicles of the type comprising two separate hydrostatic transmissions for driving the right and the left tracks of the vehicle, each including a variable-displacement hydraulic pump provided with a hydraulically operated control for varying the pump displacement. There is provided a pressure regulating device interposed in the connection between the speed control device and the hydraulically operated control for the pumps of the two hydrostatic transmissions, which is arranged to increase and reduce the pressure supplied to the hydraulically operated control of one of the pumps so as to maintain the speeds of the two tracks equal. Preferably, the system further includes a sensor arranged to detect differences in speed of the two vehicle tracks and an actuator arranged to control the pressure regulating device in dependence on the signal received from the sensor.

Abstract: A motor vehicle having a pair of front drive wheels and a rear steerable drive wheel mounted on a main frame. A sub-frame secured to the main frame intermediate the front and rear drive wheels carries an internal combustion engine and a pump assembly. The pump assembly has a first pump operable to deliver fluid under pressure to fluid operated motors operably connected to the front drive wheels and a second pump operable to deliver fluid under pressure to a fluid operated motor operably connected to the rear drive wheel. The internal combustion engine and pump assembly are located below a seat and floor with both the engine and pump assembly positioned transversely of the main frame of the vehicle. The rear wheel is mounted on the frame for angular movement about a generally upright axis. A fluid operated double acting piston and cylinder assembly operates to angularly move the rear wheel about the upright axis to steer the vehicle.

Abstract: A hydraulic drive apparatus for a wellhead pump jack which utilizes oppositely driven single-acting hydraulic cylinders as actuated by a variable volume pump having flow direction and flow volume controlled by a servo linkage and control lever. The linkage transmits oscillatory sine function motion of the walking beam for movement of the control lever as intermediate biasing force prevents nulling of the system.

Abstract: A control device for a balancer includes a load detector for determining the torque exerted on a driving screw attributable to the load driven and supported thereby. A fluid pressure control device increases or decreases the pressure input to a balancing torque generator in response to the detected load at a given time instant.

Abstract: A fluid control system (10) has a first fluid pump (12) for supplying pressurized fluid in interrupted series to first and second work elements (14,16). The first work element (14) in the series has priority which prevents simultaneous full power operation of the first and second work elements (14,16). A second fluid pump (24) is capable of supplying pressurized fluid to the second work element (16) only upon receiving a signal indicating that pressurized fluid from the first pump (12) is being directed to the first work element (14). The subject fluid control system (10) is especially useful with a tree harvesting machine where it is beneficial to propel the machine and at the same time rotate the upper structure.

Abstract: An off-the-road vehicle has wheel sets of the same or different forms such as rolls or differentially driven wheels with a hydraulic motor and gear reduction drive for each wheel set. An engine driven variable displacement fluid pump is fed by return lines from the motors, and a fluid control system is provided including a valve associated with each motor and a restricted delivery line from each valve to its associated motor, an unrestricted delivery line from each valve to the other motor, and a restricted line connecting the two motors. Each valve is biased toward a first position by a spring and fluid pressure at the associated motor and has ports connecting the pump and restricted line to the associated motor in a first position, each valve being movable toward a second position by pump output pressure and having parts connecting the pump and the other motor through the unrestricted lines in the second position.

Abstract: A steering system includes load-responsive valving which automatically routes pressure fluid to one of a pair of double-acting hydraulic actuators when steering resistance is low and which automatically routes pressure fluid to both of the actuators when the steering resistance is high.

Abstract: This movement compensation arrangement in one aspect comprises a hydraulic main motor group driven by the pressure difference between two hydropneumatic pressure containers and a hydraulic auxiliary motor group driven by a pump with an effect which can be regulated, and adapted to provide for dynamic compensation. The hydraulic main motor group is adapted to substantially take up the static load. The two motor groups are rotationally coupled to moving means. A control unit in response to input signals controls both motor groups, of which the main motor group has a stepwise and/or continuously variable displacement (FIG. 1).

Abstract: A fluid motor control system (11) assures that automatic changes of motor displacement, which are initiated by occurrence of a predetermined operational condition in the system (11), result in a change of motor speed of the desired magnitude. Flow adjustment elements (76) respond to a displacement increase by reducing the flow of working fluid available to the motor or motors (12, 13) and respond to a motor displacement reduction by increasing the available flow. In one specific form, the system (11) controls a pair of right and left side vehicle drive motors (12, 13) and automatically increases motor displacements while reducing the fluid flow supplied to the motors (12, 13) to reduce travel speed during a turn of travel direction.

Abstract: A system is disclosed for controlling the flow of fluid from a pair of pumps (15,15') to a steering system (11) and a pair of auxiliary load circuits (13,13'). The steering system includes valving (43) defining a variable flow control orifice (45), and the steering system normally operates with a pressure differential X across the variable orifice, and provides load pressure signals (47,49,49',53,53') representative of demand for fluid by the steering system. Fluid flow from the pumps is controlled by a pair of priority flow control valves (21,21') including a pair of valve members (27,27') each of which is biased by a spring (29,29') toward a position permitting flow to the steering system. The spring (29) exerts a biasing force equivalent to the pressure differential X while the spring (29') exerts a biasing force equivalent to a pressure differential Y, which is less than X.

Abstract: An improvement is disclosed in a hydraulic system (10) having a variable displacement pump (12) and being capable of delivering pressurized fluid from the pump (12) to selectively engage at least three work circuits (18) with a first (20) of the circuits (18) being normally operable up to a first pressure and a second (22) of the circuits (18) being normally operable up to a second and lower pressure. The improvement comprises circuitry (80, 92, 94, 98, 108, 120, 122, 124, 126) for selectively operating a third (24) of the circuits (18) at one of the first or second pressures or at an upstaged pressure which exceeds the first pressure and circuitry (128) for reducing the displacement of the pump (12) in response to the third circuit (24) being operated at the upstaged pressure. Such upstaged pressure is available in a controlled manner for working against particularly heavy loads. Thus, a third and higher operating level is added to a system which already operates at at least two pressure levels.

Abstract: A flow control valve assembly for controlling first and second reversible fluid motors for series or parallel operation has a direction control secton and a torque control section provided in a single valve body. The valve body has first, second, and third supply ports selectively pressurizeable by the direction control section and connected to a torque control bore in the torque control section. First and third function passages extend from the torque control bore and are connectible to the first fluid motor, and second and fourth function passages extend therefrom and are connectible to the second fluid motor. A grooved, torque control spool is disposed in the torque control bore for sliding from a series operating position wherein the grooves connect the first port to the first function passage, the second function passage to the third function passage, and the fourth function passage to the second and third ports.

Abstract: A hopper barge having at least two longitudinal air chambers interconnected pivotally at deck level, which chambers in a loading position bound an upwardly open well and in an unloading position release a discharge opening at the bottom, and comprising at least one control unit for controlling the relative position of the air chambers, with per each control unit two synchronously controlled jack means, which are each pivotally connected with at least one of the air chambers by on the one end a lever arm, which two lever arms are arranged in substantially mirror-symmetrical relationship relative to the median longitudinal plane of the vessel and being interconnected pivotally, and on the other end a hinge fixedly secured to one of the air chambers.

Abstract: A control system for plural circuits having motor-driven hydraulic pumps. As disclosed, a pair of pumps is connected in a hydraulic actuating circuit individual to that pair and the circuit includes an hydraulically operated actuator to be advanced and retracted by fluid under pressure delivered from the pair of pumps of that circuit. A single prime mover drives the pair of pumps and pumps in other circuits, and each circuit has a pressure-responsive control valve which provides for unloading a pump of the first circuit in response to increases in pressure in the various other circuits to a predetermined value at which, in the absence of such unloading, the input horsepower requirement has risen toward a value which would stall the prime mover.Pumps in several of the circuits may be sequentially and selectively unloaded.

Abstract: In a system comprising first and second drive units each including one or more hydraulic motors, a two-position valve is provided in circuit with the motors of one drive unit, the motors of the other drive unit being supplied independently of the valve; the valve has a first operative position for blocking flow of working fluid to the one drive unit and a second operative position for permitting flow of working fluid to the one drive unit, the valve being operable between its first and second positions for selective operation of one or both drive units.

Abstract: A flow divider for directing hydraulic fluid to separate hydraulic circuits, including a power steering gear which carries the divider, includes a pair of axially aligned valve spools disposed in a common bore of a valve housing. The valve spools and the bore have circumferential grooves which are in fluid communication with a source of pressurized fluid and the separate hydraulic circuits and the flow divider operates to divide the flow of pressurized fluid into two portions with a predetermined ratio between each portion and the total fluid flow.

Abstract: A pair of hydraulic motors are operatively drivingly connected to a common rotatable member and are employed for transmitting power thereto from a pair of prime movers. A first hydraulic circuit communicates with one of the hydraulic motors and includes a pump driven by one of the prime movers while a second hydraulic circuit communicates with the other of the hydraulic motors and includes a fixed displacement pump and a variable displacement pump driven by the other prime mover. A device associated with the variable displacement pump is responsive to fluid pressures in the first and second hydraulic circuits for automatically varying the output displacement of the variable displacement pump so that a predetermined relationship is maintained between the fluid pressures in the first and second hydraulic circuit.