Abstract: A variable displacement piston pump, having: a housing, a pivot assembly to pivot between minimal and maximum pivot angles; a pump cover defining an actuator bore with an actuator piston, an actuator arm extending from the actuator piston to the pivot assembly; and an electronic control unit (ECU) coupled to the pump, the ECU having: a pump controller, a linear variable differential transducer (LVDT) coupled to the pump controller and the actuator piston, and an electrohydraulic solenoid valve (EHSV) coupled to the pump controller, the ECU is configured to: determine a pivot differential for the pivot assembly between a target pivot angle and a current pivot angle; determine a position differential for the actuator piston, corresponding to the pivot differential of the pivot assembly; control the EHSV to move the actuator piston by the position differential; and determine, from the LVDT, that the actuator piston moved by the position differential.

Abstract: A hydraulic actuator includes a variable-delivery positive-displacement pump, a member able to continuously vary the delivery of the pump, the member being actuated by a ram supplied by a first directional-control valve commanded on the basis of an actuator movement instruction. The actuator comprises a second directional-control valve commanded on the basis of an output pressure of the pump, the second directional-control valve comprising two positions, one of them, known as the rest position, obtained as long as the output pressure of the pump is below a predetermined pressure and transmitting the output from the first directional-control valve to the double-acting ram and the other, referred to as the active position, transmitting the output pressure of the pump to the ram so as to reduce the output pressure of the pump without passing via the first directional-control valve.

Abstract: Control system and control method of a variable displacement hydraulic pump wherein the system includes a detection sensor for detection of the actually set displacement and a control unit for current control of a couple of solenoids controlling displacement increase and decrease.

Abstract: There are provided high power laser and laser mechanical earth removing equipment, and operations using laser cutting tools having stand off distances. These equipment provide high power laser beams, greater than 1 kW to cut and volumetrically remove targeted materials and to remove laser affected material with gravity assistance, mechanical cutters, fluid jets, scrapers and wheels. There is also provided a method of using this equipment in mining, road resurfacing and other earth removing or working activities.

Abstract: A control mechanism for a stepless transmission is a control mechanism connected to a manipulation lever in a stepless transmission and disposed outside a housing of the transmission.

Abstract: Transaxle systems for a vehicle are disclosed where each of right and left transaxle units includes a hydraulic pump, a hydraulic motor and a casing incorporating the hydraulic pump and motor. Each hydraulic pump has a pump displacement control means operatively connected to a pump control arm pivoted on the casing, and each hydraulic motor has a motor displacement control means operatively connected to a motor control arm pivoted on the casing. A single motor controlling manipulator is operatively connected to the motor control arms to simultaneously shift the motor displacement control means of the right and left transaxle units between large displacement positions and small displacement positions.

Abstract: A method and apparatus for automating some of the tasks that heretofore required operator action at headland turns or similar events are provided. The present invention automates operation of lift assist wheels and/or gull wings, such as those found on a stack-fold implement, based on the position of the tractor hitch to which the implement is coupled. An operator may control the position of the implement, such as at a headland turn, by raising and lowering the tractor hitch using a remote control. The invention enables the planter to compare the tractor hitch position relative to an implement position and control operation of the implement accordingly without additional user inputs.

Abstract: A transmission is provided for a mobile machine. The transmission may have a plurality of available gear combinations selectively engaged to produce multiple stepped output ratios. The transmission may also have a first fluid pump and a second fluid pump. The first fluid pump may be configured to pressurize a first flow of fluid. The second fluid pump may have variable displacement to pressurize a second flow of fluid. At least one of the first and second flows of fluid may be directed to cause selective engagement of the plurality of available gear combinations.

Abstract: A manual displacement control is provided for varying the displacement of a hydraulic pump. The pump has a tiltable swashplate and is used in a hydraulic system which includes a control valve having an axially movable spool for metering control fluid to modulate the swashplate position. A displacement control linkage has a non-linear coupling element and a resilient override spring serially connected between the input lever and the valve spool. A torsional centering spring is connected between the input lever and the override spring to generate a feedback force which opposes a control force applied thereto and urges the input lever to a position representative of the no flow position of the pump swashplate. An adjustable connection is provided for centering the valve spool while maintaining a corresponding neutral position of the input lever and swashplate during assembly of the displacement control.

Abstract: An operation control device for a construction machine is constructed of a remote control valve having a member moveable in proportion to an operating lever stroke and having a plurality of devices engaged with the member and operable in association therewith. A part of the plural devices include a proportional hydraulic signal generator for reducing a hydraulic pressure from a hydraulic pressure source in proportion to a moving quantity of the member and generating a signal as a pilot pressure, and a part or the other of the plural devices including a proportional electric signal generator for generating an electric signal proportional to the moving quantity of the member.

Abstract: A servo-mechanism includes a piston and cylinder unit controlled by a valve coupled in known manner by a linkage means to a movable control element to provide closed loop servo operation to position the piston and cylinder unit piston rod according to the position of the movable element. The movable element is fast with an annular gear segment of an epicyclic gear mechanism of which the sun gear forms a main control input and the planet pinion carrier forms an override input. The mechanism is of utility in an hydraulic transmission of the variable stroke pump/fixed stroke motor type, the overrride input being actuable by a pump port pressure limit sensor.

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 for a hydrostatic power transmission having a variable displacement hydraulic pump (2) and a hydraulic actuator (3) connected in a closed or semi-closed circuit, wherein the displacement of the pump or the delivery thereby is adjustable in accordance with a manipulated variable of an operating lever (13). A control unit of the system (16) is operative to calculate a hydraulic pump displacement command (X) on the basis of a manipulated variable signal (X.sub.

Abstract: A control device for a hydrostatic transmission including apparatus for sensing a speed of a prime mover which powers a variable displacement pump of the hydrostatic transmission and for regulating the displacement of the variable displacement pump in accordance with the speed of the prime mover, is disclosed. The control device also includes apparatus for transmitting a mechanical feedback signal representative of the displacement of the variable displacement pump to the control device to maintain the variable displacement pump at a displacement proportional to the speed of the prime mover.

Abstract: A variable displacement pump has a swashplate controlled by a pair of pistons. A shuttle valve communicates the highest pressure pump workport to an operator-controlled displacement control valve. A pressure-responsive override valve is connected in series between the displacement control valve and the pistons. When an override pressure is achieved, the override valve blocks communication of the control valve with the pair of pistons and communicates the pump workports directly to the pistons for rapid destroking. A neutral bypass valve is formed out of a sleeve of the displacement control valve to bypass control pressure to sump when the displacement control valve is in neutral. A pressure-reducing valve limits the pressure acting on the stroke control valve to limit response rates and reduce erosion. The override valve includes orifices which, in intermediate positions, provide flow rate control of the fluid flow to the swashplate control pistons.

Abstract: A variable displacement pump has a swashplate controlled by a pair of pistons. A shuttle valve communicates the highest pressure pump workport to an operator-controlled displacement control valve. A pressure-responsive override valve is connected in series between the displacement control valve and the pistons. When an override pressure is achieved, the override valve blocks communication of the control valve with the pair of pistons and communicates the pump workports directly to the pistons for rapid destroking.

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: 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 hydraulic system comprising a reversible variable displacement pump, a hydraulic servo motor for controlling the direction and amount of displacement of the pump, a fluid motor connected in parallel to the pump and adapted to be driven by the pump, a pilot operated directional valve for controlling the position and direction of the servo motor system, and a valve for sensing the displacement of said pump and applying a force to the directional valve opposite to the force of the pilot pressure for moving the valve.

Abstract: An electrohydraulic control arrangement for a hydrostatic machine with displacing element having a stroke determined by a control member, which has at least one pressure-actuated regulating piston arranged to adjust the control member, and a valve slider through which a pressure medium acts upon the regulating piston and which is withdrawable to a neutral position in response to adjusting the machine by a feedback signal coming from the control member in correspondence with an electrical input signal, wherein a constant pressure acts upon one side of the valve slider and a variable pressure depending upon a position of the control member acts upon the other side of the valve slider.

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 variable displacement pump control system comprising a variable displacement pump having a movable element for controlling pump displacement, a hydraulic motor for moving the movable element, and a transducer for producing an electric signal corresponding to the actual position of the movable element. A comparator compares the electrical signal from the transducer and an electrical signal corresponding to the desired displacement of the pump and produces an error signal. A control operates in response to the error signal to meter fluid flow from the pump output to the hydraulic motor. The control comprises a relief valve, a compensator valve and a servo valve. The servo valve is preferably a single-stage valve that includes damping orifices to provide stability.

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: Pump-motor hydraulic power system incorporation means to limit the power transmitted and the pressure in the transmission lines. High pressure line is connected to one end of a servo motor comprising a cylinder with a spring loaded piston therein. When the pump pressure increases above a certain amount it overcomes the spring and moves the piston and the piston rod to a blocking position, acting to limit movement of the three way control valve or to move the three way control valve back if it already exceeds the limit imposed by the power limiter's piston rod.

Abstract: In a crank press having a pedestal and a rotatable crank shaft journaled thereon and connected to a reciprocal top platen guidably mounted on the pedestal to form work pieces, the improvement which comprises a hydraulic motor mounted on the pedestal having a reversible drive shaft connected to the crank shaft, and a hydraulic transmission connected to the hydraulic motor. The transmission includes a pump assembly connected to a reservoir for delivering the pressure fluid selectively under the control of a servo directional valve in a closed hydraulic loop to the hydraulic motor for selective forward and reverse drive together with a safety control to automatically neutralize the pump assembly and control automatic braking of the hydraulic motor drive shaft.

Abstract: A drive train includes a hydrostatic transmission unit and a multiple speed range transmission unit arranged in series between a prime mover and a primary output shaft, variable displacement and torque transmitting capacity of the hydrostatic transmission unit being adjusted by hydraulic controls including a speed control valve for developing a differential pressure signal proportional to a desired rate of operation, a modulating valve for regulating the differential pressure signal corresponding to accelerating and decelerating operation of the transmission, a directional control valve for determining the direction of operation of the hydrostatic transmission unit, and a range selector valve for shifting the operating speed range of the multiple speed range transmission as the hydrostatic transmission approaches a limit of displacement, the displacement of the hydrostatic transmission being automatically reset in response to shifting of the multiple speed range transmission.