Abstract: An example valve assembly includes a meter-in valve configured to be fluidly coupled to a first source of pressurized fluid and control fluid flow from the first source of pressurized fluid into a first chamber of an actuator; a counterbalance valve including configured to open and control fluid flow from a second chamber of the actuator to a tank in response to a pilot pressure fluid signal received at a pilot port of the counterbalance valve; and a pressure reducing valve configured to be fluidly coupled to a second source of pressurized fluid and to be fluidly coupled to the pilot port of the counterbalance valve, where the pressure reducing valve is configured to receive pressurized fluid from the second source of pressurized fluid and, when actuated, provide the pilot pressure fluid signal to the pilot port of the counterbalance valve.

Abstract: A hydraulic system according to the present invention includes a rotational shaft, a hydraulic rotor supported by the rotational shaft so as to be incapable of relative rotation, an output adjuster varying a volume of the hydraulic rotor, a control shaft tilting the output adjuster, a drive motor operating the control shaft around the axis, a drive shaft disposed on a reference axis same as the axis of the control shaft and operably driven around the axis by the drive motor, a deceleration mechanism decelerating rotary power input from the drive shaft and outputs the decelerated rotary power toward the control shaft, and a housing accommodating the hydraulic rotor, the output adjuster, and the deceleration mechanism, wherein the deceleration mechanism has a hypocycloid-type deceleration mechanism disposed on the reference axis.

Abstract: A hydraulic shovel includes an engine; a hydraulic pump driven by the engine; an excavating attachment which is driven by high oil discharged from the hydraulic pump; a motor generator that assists a power supply of the engine; and an assist control unit that controls the motor generator to assist the engine in a latter part of the excavating operation by the excavating attachment.

Abstract: The present invention includes an information generator to set a lever manipulation amount total sum decrease flag during a period when a lever manipulation amount total sum is decreasing, a first processor to process an engine actual output, an engine actual output latching function block to output the maximum value of the engine actual output until the present during a period in which a lever manipulation amount total sum decrease flag is not set, and output the present engine actual output during a period in which the flag is set, a second processor to output an engine target output based on the engine output, and a controller to control the engine speed under limitation of the engine target output.

Abstract: A hydraulic circuit includes a first pressurizing section for pressurizing a wheel cylinder by operating a master cylinder, and a second pressurizing section for pressurizing the wheel cylinder independently of operation of the master cylinder.

Abstract: A hydraulic transmission (21) has an electric actuator (86) for changing its output/input rotation speed ratio. A controller 90 of the actuator memorizes a command current value to the actuator supposing that load is not applied on the hydraulic transmission, and calculates a value of load applied on the hydraulic transmission by calculating a difference between an actual command current value to the actuator and the memorized command current value. A command current value is compensated based on the value of load, and the actuator receives feedback to be controlled. A vehicle may have a differential mechanism (10), which combines rotation powers on input side and output side of the hydraulic transmission. A detector (82) detects rotation speed of a main speed change output shaft (27) serving as an output shaft of the differential mechanism.

Abstract: A hydrostatic steering system of the type including a fluid controller (21) for controlling the flow of fluid from a source (11) to a steering actuator (19) in response to movement of a steering wheel (W). The controller (21) is of the type having a fluid meter (65) including a moveable star member (95), the movement of which corresponds to the flow of fluid to the actuator (19). The controller includes a sensor assembly (125) which senses the movement of the star member (95) and generates an electrical signal (127) representative of the fluid flow through the fluid meter (65).

Abstract: Operating side link members corresponding to working side link members of a working device are provided in a device for operating working equipment. Rotation of the working side link members is detected by a rotation sensor. A motor is driven in response to a signal from the rotation sensor. A differential detecting portion has a working side movable portion driven both in a forward direction and a reverse direction by the motor, an operating side movable portion that is shiftable both in the forward direction and the reverse direction within a range from a neutral position to the working side movable portion, and a differential sensor for detecting a relative shift from the neutral position of the operating side movable portion to the working side movable portion.

Abstract: A hydraulic control system is provided for regulating the slew rate of a servovalve driven actuator within design parameters despite widely varying load conditions. The servovale flow is maintained constant in accord with the integration of the difference between a set slew rate command signal and a measured slew rate feedback signal. Where a plurality of such actuators are driven from a single hydraulic pump, this regulation of servovalve flow also enables the pump supply pressure to remain constant despite widely varying load conditions on the individual actuators in the system.

Abstract: A remote control shifting system for a mechanical transmission. The transmission is operated by two pneumatic cylinders, a selecting cylinder operating in the direction of shift path selection and a shifting cylinder acting in the direction of shifting. The shifting cylinder operates with two force stages, a lower force for effecting synchronization of gears about to be engaged, and a higher force level for actually engaging or disengaging the selected gears. A remote shift control unit is designed to closely emulate the action of a direct-operating manual shift level. During the synchronizing phase, the shift lever moves easily in the shifting direction. After a preliminary movement, however, further movement is allowed only against considerable resistance, as if conventionally mechanically forcing gears into meshing engagement.

Abstract: A flexible bellows connecting device which positions an output member has a pair of jacks (1,2) equipped with deformation sensors (12,13). A pair of variable capacity bellows pump reservoirs (3,4) permit predetermined motion of the jacks. An electric motor (19) drives the pump. The sensor signals provide deformation difference signal feedback to the electronic control system which may include a microprocessor (5) for closed loop position control.

Abstract: A control system for airships and the like that incorporates optically encoded control signals and a compressed fluid power source to power a remote control station to decrease the susceptibility of the control system to uninterruption or disablement due to electromagnetic interference. The compressed fluid power source provides means of driving an electrical generator at a remote location to power the electrical portion of the control system at the remote location in addition to providing primary power for movement of the controlled devices.

Abstract: A position transmitter which can be incorporated in a pneumatic-pneumatic or electro-pneumatic converter, and which readily provides for calibration between a zero position and a maximum position of a device to be actuated by the converter. The invention also provides a virtually non-interacting zero and span or full scale adjustment, for ease of calibration.

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: The valve disclosed herein functions as a flow matching device. By employing such a valve, hydraulic systems may be implemented in which filling and emptying of a variable volume load, such as a hydraulic piston, may be accomplished through simple check valve structures at controlled flow rates.

Abstract: A working vehicle having a working device mounted on a swivel base rotated by a hydraulic motor. There is provided a control system which causes the swivel base to start and stop smoothly at highest possible standard speeds which are preset for an entire swivelling range.

Abstract: This invention relates to integrated electro-hydraulic actuators for use aboard aircraft or elsewhere. A balanced, double-acting hydraulic ram or motor (12) is connected between a support (16) and a member to be moved relative to the support. The ram includes first and second changeable volume hydraulic chambers (30, 32). A reversible hydraulic pump (38) is connected by a pair of conduits (44, 46) to the ram chambers (30, 32). The pump (38) displaces hydraulic fluid from one chamber to another for the purpose of causing a pressure differential between them. A hydraulic accumulator (60) provides leakage makeup fluid to the actuator, and further provides a quiescent pressure to the actuator when it is in a substantially nonoperative condition. A conduit (62) may connect the accumulator (60) to the ram (12). A laminar leakage flow path within the actuator permits hydraulic connection of the accumulator (60) to the ram (12) without use of valves.

Abstract: An electronic control system for a variable displacement pump comprises apparatus for sensing the actual position of the displacement determinative element and the actual rotational speed of the pump cylinder block, and for producing representative signals which are combined to produce a signal indicative of actual output flow rate. The displacement determinative elements position and the cylinder rotational speed are sensed directly by sensors mounted within the housing of the pump. The speed sensor is disposed in close proximity to, and aligned with marks inscribed on, the outer surface of the rotatable cylinder block. The volumetric efficiency of the pump is also sensed by and used to determine the actual flow rate.

Abstract: In the hydraulic system disclosed herein, a flow matching device is employed to implement a system in which filling, emptying and holding of a variable volume load, such as a hydraulic piston, may be accomplished at controlled flow rate by a hydraulic circuit including a flow matching control valve.

Abstract: This disclosure pertains to a completely digital, electrically powered servo wherein the servo actuator is minutely incremented at a frequency proportional to the magnitude of an error binary number. The binary error is derived from the difference of a binary reference representing the commanded position of the actuator and a binary feedback representing the position of the actuator. The direction of each increment has the polarity which reduces the difference between the reference and feedback binary numbers. The power unit of the servo is electrohydraulic; however, the servo is entirely electrically controlled and powered. Hydraulic fluid is confined to the power unit where it serves as a link between two solenoid driven piston pumps, a common mode volume adjuster and a hydraulic actuator. The direction the actuator is incremented is dependent on which of the two solenoids the error polarity directs pulsed electrical power.

Abstract: A control system for a hydraulic circuit having a variable displacement hydraulic pump, and an actuator driven by the pump, in which a pump control controls a displacement volume varying member of the pump based on an operating signal giving a command with respect to the position thereof and a detector signal indicative of the actual position thereof while restricting the operating speed of the member to a level below a predetermined maximum speed.

Abstract: A control system is provided for a combine or other vehicle having an engine for driving both the ground wheels of the vehicle and at least one auxiliary mechanism, such as the crop-processing mechanisms of a combine. The engine is coupled to the ground wheels through a hydrostatic transmission, and the power takeoff for the auxiliary mechanism is located on the engine side of the transmission. A speed droop governor regulates the fuel input to the engine in response to changes in the engine speed. Transmission control means adjusts the setting of the hydrostatic transmission, and thus the load applied to the engine via the transmission, in response to changes in engine speed or another parameter that varies with engine load so as to control the speed changes effected by the droop governor.

Abstract: An electrohydraulic control system which includes first and second electrically controlled fully variable hydraulic pumps adapted to be driven by the vehicle engine. In the specific embodiment of the invention herein disclosed, the first pump is coupled to the steering and braking control valves, and the second pump is coupled to the bucket and hoist control valves. An electrically controlled poppet valve selectively interconnects the respective pump outputs. Operator-responsive controllers, namely a bucket/hoist joy-stick controller, a vehicle propulsion controller and a steering controller, provide associated electrical signals as respective functions of operator demand. Electrically operated valves control application of hydraulic fluid to the bucket and hoist drive mechanisms, and pressure and position sensors are connected to such valves and actuating mechanisms.

Abstract: An electronic closed loop piston pump servo control system including a swash plate within the pump housing which controls pump output as a function of its position about a rotational axis, means for altering the position of said swash plate, means for producing electric signals representative of the desired and actual swash plate angular positions, and means for comparing these signals and producing a control or error signal to the means for altering the swash plate position as a function of these signal differences. The means for producing electric signals representative of the actual swash plate position includes a rotary potentiometer mounted in the pump housing and directly connected to the swash plate along a common axis of rotation. This potentiometer produces a d.c. signal indicating the angular position of the swash plate on this common axis.

Abstract: An automatic neutral point detecting system for a hydraulic pump equipped with a displacement varying device capable of shifting both in a (+) direction and in a (-) direction and connected to at least one hydraulic actuator to form a hydraulic circuit to drive the hydraulic actuator. The system includes pressure sensors for sensing the port pressures of the hydraulic pump, a shifting detector for detecting the shifting of the displacement varying device, a closing device for closing the hydraulic circuit and blocking the flow of a hydraulic fluid, a start switch for giving a command to start detection of the neutral point of the hydraulic pump, and a control unit for detecting the neutral point of the hydraulic pump.

Abstract: A failure detection system for a hydraulic pump (1) having a displacement volume varying device (1a) and connected to at least one hydraulic actuator (4) to constitute a hydraulic circuit for driving the hydraulic actuator. The system includes means (7a, 7b) for sensing the discharge pressure of the pump, means (6) for detecting the value of shifting of the displacement volume varying device, means (5, 24) for closing the hydraulic circuit to block the flow of a hydraulic fluid through the circuit, starting means (9) for giving a command to start checking on the pump to see if it is normally functioning, and a control unit (2, 23, 28, 29) for performing checking on the pump to see if it is normally functioning. The control unit includes means (S-5, S-5') responsive to the command given by the starting means for giving a command to activate the closing means, data collecting means (S-11) for causing the displacement volume varying device to shift based on information (P.sub.a, P.sub.

Abstract: In the preferred form, the invention disclosed herein provides a single servo control valve to modulate the flow of control fluid to a servo mechanism of a variable displacement pump wherein the single valve is provided with both a manual primary input and an electro-hydraulic secondary input which modulates the primary input. The servo valve is spring biased toward a neutral position with the manual input displacement command being applied to such servo valve through a resilient linkage. Also applied to the servo valve is a hydraulic signal which is electrically controlled to modify the displacement of the servo valve relative to the yieldably applied manual input.

Abstract: A drive mechanism for ships or the like having at least one main propeller or the like drivable by at least one main motor and further having at least one drivable auxiliary mechanism, for example a maneuvering propeller. An energy producer is drivable by the main motor. A further motor is driven by the energy producer and arranged for driving the drivable auxiliary mechanism. An adjusting mechanism is provided for adjusting energy emitted by the energy producer or absorbed by the further motor. A regulator adjusts the adjusting mechanism to a preselected energy output. The main motor and the auxiliary mechanism are sized such that in the higher part of the speed range of the main motor, the sum of the energy required to drive the propulsion means at that speed and simultaneously drive the auxiliary mechanism at that speed exceed the output available from the main motor.

Abstract: An arrangement is described for controlling a winch used in mining machinery, wherein the direction of operating a winch and speed thereof are controlled by changing the position of a control element of a fluid pump for supplying a fluid into a fluid pressure recirculating circuit, by a device incorporating the fluid pressure recirculating circuit and a control circuit. The arrangement is characterized by feeding ON/OFF signals for giving instructions of a position to a control element, by a bi-polar pulse generator. Pulse from the bi-polar pulse generator are fed to a reversible BCD counter by pressing push buttons, and comparing a voltage generated via a D/A converting circuit from the reversible BCD counter with a voltage generated from a potentiometer coupled to the control element according to the position of the control element to be selected, thereby controlling the instruction of the position of the control element; and setting a speed of the winch by pressing the push buttons.

Abstract: To permit mechanical override of an electrical command system to control deflection of the swash plate or eccentricity of an axial or radial piston pump, for example upon failure of the electrical control system, a group of valves 5-8 are connected to an electrical control unit 23 and an additional control valve 4, 4' with a manual control lever 18', 30' is provided, the deflection of the swash plate 1 or eccenter ring 28 of the pump being sensed by a position transducer 22 moved by a linkage which includes the manual control lever. In normal operation, the manual control lever is maintained by spring pressure to deactivate the control valve but, under emergency conditions, the manual control lever will operate the first control valve 4, 4' to admit hydraulic control fluid to position the swash plate, or eccenter ring, respectively, the consequent movement of which is fed back through the linkage to the manual control lever.