Abstract: A hydraulic four-wheel-drive working vehicle includes a hydraulic pump unit having a hydraulic pump main body of a variable displacement type, a pair of left and right first motor devices driving a left and right first driving wheels, and a pair of left and right second motor devices driving a left and right second driving wheels, wherein each of the pair of first motor devices and the pair of second motor devices includes a hydraulic motor main body forming an HST in cooperation with the hydraulic pump main body, a motor volume adjusting mechanism, and a hydraulic actuating mechanism that operates the motor volume adjusting mechanism, and the hydraulic actuating mechanisms in the pair of first motor devices and the pair of second motor devices are operated and controlled with use of hydraulic fluid from a single hydraulic pressure source.

Abstract: A method and arrangement for controlling a function of a work implement utilizing a device including a source of pressurized fluid (1), a circuit of pressurized fluid (2) for driving the work implement, an electronically controlled hydraulic valve (5) being arranged in the circuit of pressurized fluid (2) for controlling the function of the work implement, a control unit (4) for controlling the hydraulic valve (5) based upon a signal from a control member (3) for transmitting a control command to the control unit (4), wherein the control unit (4) is arranged for controlling the hydraulic valve (5) in accordance with a smooth mode function or an abrupt mode function. The opening time for opening the hydraulic valve (5) to a predetermined opening degree is changed when switching from one operating mode function to the other operating mode function.

Abstract: A hydrostatic system and method of operation thereof, wherein at least one of a fluid motor and a pump of the system has a displacement which is variable for controlling a speed of operation of the motor, the pump being driven by an engine, and a controller configured for monitoring the speed of operation of the motor and an operating characteristic of the engine and automatically controlling the displacement responsive thereto, wherein if the operating characteristic is indicative of engine performance above a predetermined threshold, the controller will control the displacement for maintaining the speed of operation of the motor at about a predetermined value, and, if the operating characteristic is indicative of engine performance below the threshold, the controller will hold the displacement at a constant value. As a result, the controller can prevent the system from further decreasing the engine performance.

Abstract: A hydrostatically driven vehicle has an engine operating a variable displacement propel pump, a displacement of which can vary based on an angle of a rotating swashplate, such that a fluid flow impelled by the pump transfers power to at least one propel motor rotating a wheel of the vehicle. An electronic controller of the vehicle senses an operating parameter of the system, for example, the angle of the rotating swashplate or the direction and speed of rotation of the propel motor with a sensor to yield an actual signal, and relays the actual signal to an electronic controller. The controller determines a desired angle for the rotating swashplate based on the control signal, and compares it to the actual signal from the sensor. Motion of the vehicle is stalled when the angle signal differs from the desired angle by a predetermined extent and for a predetermined period.

Abstract: A system for controlling a power output is disclosed. The system includes a hydraulic actuator configured to output a first torque and a source of pressurized fluid configured to supply a flow of pressurized fluid to the hydraulic actuator. The system further includes a controller configured to control the flow of pressurized fluid as a function of the first torque, a predetermined torque, and changes to the first torque caused by a load operatively connected to the hydraulic actuator.

Abstract: [Object] To permit an precise and easy adjustment of a pump absorption torque of a main pump in accordance with environmental conditions or the like when a sub-pump different in characteristics from the main pump is connected to a prime mover. [MEANS FOR ACHIEVING THE OBJECT] An adjustment switch 25 is arranged.

Abstract: When employing synthetically commutated hydraulic pumps (1), a time delay between a change in fluid flow demand (15) and the resulting fluid flow output (13) can be observed. It is suggested to use a time evolvement function, taking into account the time evolvement of the fluid flow demand and/or the time evolvement of the pumping strokes, to modify the actuation of the electrically commutated valves.

Abstract: The invention improves a pump provided with an eccentric cam bearing, a drive bearing, a drive shaft, an electric drive motor, and a pump housing.

Abstract: The invention relates to a hydraulic supply system with an adjustable pump for supplying at least one safety-critical consumer to be supplied as a matter of priority and at least one non-safety-critical consumer. The adjustable pump control is configured for adapting the flow generated by the pump to the instantaneous requirements of the consumers and has a flow control valve for controlling the pump. The adjustable pump control further comprises switching, hydraulically actuated valves which cause the priority supply of the at least one safety-critical consumer and are activated by a hydraulic release signal generated in the region of the at least one safety-critical consumer.

Abstract: A hydrostatic system and method of operation thereof, wherein at least one of a fluid motor and a pump of the system has a displacement which is variable for controlling a speed of operation of the motor, the pump being driven by an engine, and a controller configured for monitoring the speed of operation of the motor and an operating characteristic of the engine and automatically controlling the displacement responsive thereto, wherein if the operating characteristic is indicative of engine performance above a predetermined threshold, the controller will control the displacement for maintaining the speed of operation of the motor at about a predetermined value, and, if the operating characteristic is indicative of engine performance below the threshold, the controller will hold the displacement at a constant value. As a result, the controller can prevent the system from further decreasing the engine performance.

Abstract: A power device for motor vehicles installed on a motor vehicle with an internal combustion engine is composed of a first variable displacement hydraulic activator (107), a second variable displacement hydraulic activator (108), a planetary gear mechanism (103) and a mechanical transmission (104). The power device further includes a hydraulic control device (109) and an electronic control device (112) which are used to control the first and second variable displacement hydraulic activators. The control device may carry out the following controls, that is, during the period when the engine outputs power, part of mechanical energy is converted into electric energy via the motor to be stored in the chargeable cell when the power requirement from the motor vehicle increases.

Abstract: A method of controlling a work vehicle includes detecting an operational condition of a powertrain which is adapted to propel the vehicle, wherein a power source in the powertrain is adapted to operatively drive at least one variable displacement pump, wherein the pump is adapted to operatively drive at least one hydraulic actuator via hydraulic fluid for moving a work implement and/or steering the vehicle. The method further includes comparing the detected operational condition with a predetermined critical condition, limiting a maximum available displacement of the pump and thereby establishing an available pump displacement range if the magnitude of the detected operational condition is within the predetermined critical condition, detecting a hydraulic load associated to the actuator, and adjusting the pump displacement of the pump in response to the detected hydraulic load within the available pump displacement range.

Abstract: The servo-control system for hydraulic unit according to the invention comprises a pump driven by a motor feeding hydraulic fluid to a vibrator or vibrating system comprising eccentric weights driven in rotation by at least one hydraulic motor receiving said fluid. It also comprises adaptation means for continuous adaptation of the rotation speed of the motor of the hydraulic unit in relation to the energy actually consumed by the vibrator.

Abstract: The present invention relates to the use of aquaporin containing membranes in the production of salinity power. The membranes are preferably lipid bilayers incorporating reconstituted aquaporin channels, e.g. entrapped between porous support materials, or alternatively enclosing a highly hydrophobic porous support material. Also disclosed is a salinity power plant.

Abstract: A load control structure for a work vehicle comprises: a device for detecting operating position of a manually operated speed change operating element; an engine load detection device for detecting load on an engine of the work vehicle; a swash plate position detecting device for detecting an operating position of a swash plate of a variable displacement pump of a hydrostatic continuously variable speed change device; a pump operating device for steplessly operating the swash plate of the variable displacement pump; a motor operating device for operating a swash plate of a variable displacement motor of the hydrostatic continuously variable speed change device between at least two speed change positions including a higher speed position and a lower speed position; a control device for controlling the operations of the pump operating device and the motor operating device.

Abstract: A vehicle includes an integrated drive module coupled to an axle thereof. The module includes a hydraulic motor configured to provide motive power at an output shaft, and a differential for distributing the motive power to right and left portions of the axle. The hydraulic motor and the differential are encased within a common housing. The vehicle may include a second integrated drive module having, within a housing, a second hydraulic motor (or multiple hydraulic motors), and a second differential coupled thereto and configured to distribute motive power to right and left portions of a second axle. The second module may also include a transmission within the same housing. The transmission may be a two speed or other multi-speed transmission. The second module is configured to operate in neutral while power demand is below a threshold, and to engage while the power demand exceeds the threshold. The second module may be configured to remain engaged for full-time four-wheel-drive operation.

Abstract: A hydraulic control apparatus 1 includes a switch valve 11, an adjustment valve 12, and a valve control device 13. The adjustment valve 12 has a fluid chamber 15, a valve body 14, and a back pressure chamber 17. A restrictor is formed between the valve body 14 and a wall defining the fluid chamber 15 and connects the cylinder line 32 to the switch valve line 33. The opening degree of the restrictor changes in correspondence with movement of the valve body 14. When the switch valve 11 is located at a neutral position or a supply position, the valve control device 13 applies the fluid pressure in the cylinder line 32 to the back pressure chamber 17. When the switch valve 11 is located at a drainage position, the valve control device 13 applies a pilot pressure lower than the fluid pressure in the cylinder line 32 to the back pressure chamber 17.

Abstract: A motor having two series of distribution ducts each having two groups of ducts. The displacement selector is able to occupy a large displacement position in which the first groups of distribution ducts of the first series are connected to a main duct while the second groups are connected to the other main duct, and a small displacement configuration in which the first group of distribution ducts of the first series is connected to a main duct, the second group of distribution ducts of the first series is connected to the other main duct and a bypass connection exists between the first and the second group of distribution ducts of the second series. The device has a restriction in order, in the small displacement configuration, to restrict this bypass connection.

Abstract: A fluid pump control system for excavators enables fluid pumps to produce hydraulic flows of a quantity great enough to actuate hydraulic actuators for smooth composite operations. The system includes variable displacement fluid pumps, fluid quantity control mechanisms for controlling the discharge quantity of the respective fluid pumps, fluid quantity control signal lines respectively connected to the fluid quantity control mechanisms, signal pressure control lines for bringing the fluid quantity control signal lines into connection with a fluid tank to drop the fluid quantity control signal pressures within the fluid quantity control signal lines, and a plurality of cutoff valves attached to the signal pressure control lines in tandem and shiftable in concert with the shifting movement of spools of a control valve for increasing the fluid quantity control signal pressures within the signal pressure control lines in proportion to the shifting amounts of the cutoff valves.

Abstract: A hydraulic circuit comprises a hydraulic cylinder, an accumulator, and a bi-directional variable displacement hydraulic pump for managing flow between a head side of the hydraulic cylinder and both of a rod side of the hydraulic cylinder and the accumulator.

Abstract: The invention discloses a hydraulic control arrangement for controlling a number of consumers, particularly of a mobile working machine. In addition to the consumers of the control arrangement, an additional consumer should be able to be connected to a power beyond port. All consumers and power beyond consumers are supplied with hydraulic fluid by a pump. An input pressure scale is provided downstream of the pump, and the greater of the load pressures of the consumers or of the at least one power beyond consumer is applied to the control port of said input pressure scale.

Abstract: A method of controlling a motor includes monitoring a pressure in a circuit supplying a pressurized fluid to the motor, determining a difference between the monitored circuit pressure and a desired circuit pressure, and determining an actuator command for an actuator that is capable of adjusting a pressure of the pressurized fluid supplied to the motor. The actuator command is determined based on the difference between the monitored circuit pressure and the desired circuit pressure, and is independent of a position of the actuator. The method also includes operating the actuator based on the actuator command.

Abstract: A hydraulic motor unit including a hydraulic motor (1?) which is connected to two working lines (3,4). The swiveling angle (?) of the hydraulic motor (1?) is adjustable by an adjusting unit (7) which is provided with a regulating piston (8) having two piston surfaces (9, 10). The regulation pressure acting on a first piston surface (10) in a regulation pressure chamber (12) can be adjusted by a control valve (13). The control valve (13) adjusting the regulation pressure is movable between two final positions. The pressure of a working line (3, 4) is applied to a first measuring surface (23) of the control valve (13) adjusting the regulation pressure while a second, opposite measuring surface (25) of the control valve (13) is impinged upon by a control pressure piston (34) at a force that depends on the control pressure only once a threshold value of a pipe (28, 18?) supplying control pressure has been exceeded.

Abstract: A travel control device enables a crawler type hydraulic excavator to start slowly regardless of the preset speed ratio whenever the manipulation amount of a manual travel control device is small. The travel control device includes left and right travel motors respectively provided with speed changing mechanisms, a high speed shifting valve provided on a high speed signal line for cutting off or transmitting a high speed signal pressure to the speed changing mechanisms, a travel signal detection means for detecting a travel control signal pressure outputted from manual travel control devices. A shutoff valve is provided on the high speed signal line for closing or opening the high speed signal line to keep the speed changing mechanisms in a low speed condition or a high speed condition depending on the magnitude of the travel control signal pressure supplied from the travel signal detection means.

Abstract: A hydraulic control system for a working machine according to the present invention includes a regulator control valve for controlling an operation of a pump regulator and a controller for sending a control signal for changing a discharge quantity of the pump to the regulator control valve in accordance with an operation amount of an operating device. This system further includes a fail-safe valve disposed in a control line joining the pump regulator and the regulator control valve. The fail-safe valve is configured so as to switch from an ordinary position to a fail-safe position in accordance with a failure signal indicative of failure in the regulator control valve.

Abstract: Disclosed are a control arrangement for actuation of at least two hydraulic consumers, and a method for actuation of these consumers. The latter are supplied with pressure medium through the intermediary of a pump, wherein a respective meter-in orifice and a pressure compensator arranged downstream from the latter are provided between the consumers and the pump. In accordance with the invention, adjustment of the pump is performed in dependence on the target values to which the meter-in orifices are set.

Abstract: A method for compensating a flow rate at a neutral position of an operation lever of construction equipment is adapted so that when RPM of an engine becomes different, an actuator can be identically driven according to an operating amount of the operation lever.

Abstract: A hydrostatic transmission vehicle comprises: a fuel adjustment position detection portion (681) which detects an operation position of a fuel adjustment portion (68); a deceleration operation position detection portion (691) which detects an operation quantity of a deceleration operation portion (69); and a controller (9) which controls a displacement of a hydrostatic transmission (7), and the controller (9) comprises: an operation state judgment portion (91) which judges operation states of the fuel adjustment portion (68) and the deceleration operation portion (69) based on detection values acquired by the fuel adjustment position detection portion (681) and the deceleration operation position detection portion (691); and a displacement control command generation portion (94) which generates a displacement control command which differs depending on a case where an engine revolution number is restricted by the fuel adjustment portion (68) and a case where an engine revolution number is restricted by the dec

Abstract: The invention relates to a hydrostatic vehicle drive system (1) comprising a first and a second hydraulic pump (2, 3), and a first and a second hydraulic motor (7, 12). Said hydraulic pumps (2, 3) and said hydraulic motors (7, 12) are coupled in such a way in a differential lock operation that a first connection (14) of the first hydraulic pump (2) is connected to a first connection (8) of the first hydraulic motor (7); a second connection (6) of the first hydraulic motor (7) is connected to a first connection (10) of the (10) of the second hydraulic pump (3); a second connection (9) of the second hydraulic pump (3) is connected to a first connection (13) of the second hydraulic motor (12); and a second connection (11) of the second hydraulic motor (12) is connected to a second connection (5) of the first hydraulic pump (2). The absorption volume of the first hydraulic motor (7) and the second hydraulic motor (12) can be respectively adjusted by means of an adjusting device (20, 21).

Abstract: A hydraulic pump of a driving force distribution apparatus for right and left axles includes a pump shaft, a swash plate supported tiltably, swash plate tilting and holding mechanism unit for tilting and holding the swash plate to one side or to the other side depending on the direction of rotation of the pump shaft, and a hydraulic oil supply mechanism unit having a cylinder block. The cylinder block holds pistons which reciprocate inside cylinder holes while making contact with a tilt surface of the swash plate at their extremities. When the pump shaft rotates in a forward or reverse direction, the pistons reciprocate to supply hydraulic oil sucked from a tank to a suction port of an operation control valve. Thus, the driving force distribution apparatus can apply relative rotating forces to right and left axles even during backward running, with no increase in the size of the apparatus.

Abstract: In a hydraulic machine, hydraulic pump failure is detected and the pump lifespan is estimated before the pump failure occurs. The discharge pressure 122, oil temperature 126, and drain filter differential pressure 120 are measured, a correlative relationship 128 between the filter differential pressure and the discharge pressure is determined, and a representative filter differential pressure 130 is calculated from this correlative relationship. Using an oil temperature-differential pressure correlation function, the representative differential pressure value 130 is corrected so that the variable component 132 caused by the oil temperature 126 is eliminated therefrom. The long-term trend and the short-term trend of the increase over time of the corrected differential pressure is calculated. A pump failure is predicted or the pump lifespan is estimated based on the degree of deviation between the long-term trend and the short-term trend.

Abstract: An articulate vehicle has first and second frames, which are coupled to each other at proximal ends thereof with respect to the vehicle through a coupling part so as to be relatively rotatable around a vertical axis according to steering operation. The first and second frames are distributed at front and rear portions of the vehicle. The first frame supports a first transaxle apparatus having first axles, and the second frame supports a second transaxle apparatus having a pair of second axles. A gearbox is disposed near the coupling part and provided with a pair of mutually drivingly connected horizontal shafts which are variable in relative angles thereof around the vertical axis according to steering operation. One of the horizontal shafts is drivingly connected to a power take-off shaft for extracting output power of a speed-changing arrangement in the first transaxle apparatus. The other of the horizontal shafts is drivingly connected to an input shaft of the second transaxle apparatus.

Abstract: In a hydraulic controller for construction machine according to the present invention, wherein there are provided regulators for each of a first and a second capacity variable hydraulic pump, each of the regulators being controlled, detecting the discharge pressure of each pump, in such a manner that one of the pumps absorbs a part of torque while the other thereof absorbs the remaining torque, and wherein a boom raising operation causes pressure oil from the pumps to be joined together and then supplied to a boom cylinder, while also a rotating operation causes pressure oil from the second pump to be supplied to a rotating motor, is provided a flow rate distribution controller adapted to control the regulators in such a manner that a difference in flow rate is provided between the pumps so that the first pump shows a higher flow rate at the start of a combined operation of raising and rotating, and that, on a steady rotating state which results in an increase in the discharge pressure difference between the

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 control device for a working machine according to the present invention comprises a capacity variable pump for supplying working oil, a controller for controlling the discharge amount of the pump, a control valve for controlling the working oil discharged from the pump, a hydraulic actuator operated by the working oil from the control valve, an operating lever for operating the hydraulic actuator, and a relief valve to be operated when the pressure of the working oil is a relief pressure or more. The controller has a dynamic emulation model of a hydraulic driving device, and is constituted to estimate the pressure oil flow rate passing through the relief valve from the emulation model according to the operation amount of the operating lever, and to control the pump flow rate of the pump so that the relief flow rate estimation value gets close to zero. According to this, relief loss can be precisely reduced without generating a response delay or pressure loss, and the power can be saved.

Abstract: A plurality of hydraulic actuators are connected by valve assemblies to fluid supply and return conduits. Desired operating velocities are specified for the hydraulic actuators and used to define the amounts of fluid flow required by each actuator to move at the respective velocity. Provide the requisite flow amounts, fluid at related pressures must be provided at the different hydraulic actuators. In order for those pressures to occur, a pump has to furnish fluid at a greater pressure to allow for supply conduit losses. A process is provided for determining the pressure that the pump must provide to satisfy the greatest pressure that is necessary for the desired operation of all the hydraulic actuators.

Abstract: An agricultural-implement hydraulic circuit includes a pump supplying pressurized fluid to a first service line and a second service line via a feed line and a device for varying the flow rate of the pump. A distributor valve is disposed between the first service line and the second service line, with the first service line and the second service line being connected and disconnected according to a position of the distributor valve. A hydraulic motor is coupled to the first service line through the valve and discharges fluid to a return line. A hydraulic actuator is coupled to the second service line. An indicator-valve assembly is coupled to the feed line, with the indicator-valve assembly including an indicator sensitive to pressure in the feed line such that the indicator indicates a predetermined pressure in the feed line to an operator.

Abstract: A control arrangement for a hydraulic system is disclosed. The system comprises a variable displacement hydraulic pump (4), which is connected with a hydraulic drive motor (16) by a supply line (11) and a return line (12). The system also includes a pump controller (4a) which is adapted to vary the displacement of the pump (4). The control arrangement includes a first feedback element in the form of an oil temperature sensor (19), which provides the pump controller (4a) feedback of the evolution of the oil temperature. The pump controller (4a) is adapted in vary the displacement of the pump (4) in response to said feedback. A second feedback element is constituted by a pressure limiter valve (15c), which provides to the pump controller (4a) feedback of the pressure in at least a feedback portion (12a) of the return line (12).

Abstract: A vehicle control system having an engine and a hydro-mechanical transmission, which further comprises a decelerator for changing target engine speed according to the operating amount of a decelerator pedal; a hydrostatic transmission unit controlling means for controlling a hydrostatic transmission unit so as to make the actual speed of the engine coincident with the target engine speed; and engine controlling means for controlling the engine such that if the target engine speed is changed from a first target value to a second target value lower than the first target value by the decelerator, the output torque of the engine is reduced, while keeping the ratio of the amount of change in the output torque of the engine to the amount of change in the target engine speed constant or substantially constant.

Abstract: An articulate vehicle has first and second frames, which are coupled to each other at proximal ends thereof with respect to the vehicle through a coupling part so as to be relatively rotatable around a vertical axis according to steering operation. The first and second frames are distributed at front and rear portions of the vehicle. The first frame supports a first transaxle apparatus having first axles, and the second frame supports a second transaxle apparatus having a pair of second axles. A gearbox is disposed near the coupling part and provided with a pair of mutually drivingly connected horizontal shafts which are variable in relative angles thereof around the vertical axis according to steering operation. One of the horizontal shafts is drivingly connected to a power take-off shaft for extracting output power of a speed-changing arrangement in the first transaxle apparatus. The other of the horizontal shafts is drivingly connected to an input shaft of the second transaxle apparatus.

Abstract: A pump displacement control arrangement uses the inherent swivel torques of a fluid translating device in cooperation with a proportional force feedback to more consistently and precisely control the displacement of the fluid translating device. The subject invention uses a variable displacement control arrangement having an actuator mechanism coupled to a swash plate of the fluid translating device and controlled by a proportional valve arrangement to control the displacement of the fluid translating device. A force feedback mechanism is disposed between the actuator mechanism and the proportional valve arrangement and provides a more precise and repeatable displacement control.

Abstract: A hydraulic control circuit of a boom cylinder for a work machine, which, when controlling the supply and discharge of pressurized oil with respect to a boom cylinder, improves fuel efficiency, work efficiency in combined operations, and work efficiency and operationality in work of difficult boom operations, such as debris raking-up work and bumping work, etc. The hydraulic control circuit of a boom cylinder is provided with a first change valve for holding the boom control valve in the neutral position, a communication line for causing the head side oil chamber and the rod side oil chamber to communicate with each other, an opening and closing valve for opening and closing the communication line, and a pilot operation check valve that is changed to an unidirectional state where, although an oil flow from the head side oil chamber to the rod side oil chamber is permitted, a reverse flow is hindered, and a bi-directional state is permitted where the oil flows in both directions.

Abstract: A method is provided for recovering energy in a hydraulic circuit. The hydraulic circuit includes a pump having a swashplate and being in fluid communication with a hydraulic actuator via a valve. The method includes sensing an overrunning load condition in the hydraulic circuit, actuating the valve to provide fluid from the hydraulic actuator to the pump under the overrunning load condition, and producing a torque output from the fluid provided to the pump. Also, a method is provided for recovering energy in a hydraulic circuit including a pump and a motor in fluid communication with a hydraulic actuator via a valve. The method includes sensing an overrunning load condition in the hydraulic circuit, actuating the valve to provide fluid from the hydraulic actuator to the motor under the overrunning load condition, and producing a torque output from the fluid provided to the motor.

Abstract: The present invention is a control system for conditioning movement of a work implement during a work cycle. In one embodiment, the control system comprises an electronic-hydraulic valve connected to the work implement and a computer system having a central processing unit and a memory device. The control system further comprises a mode control module stored on the memory device. The mode control module is generally adapted to detect whether the control handle of the work implement is signaling for operating in a smooth mode or an abrupt mode, and to output a control signal to the electronic-hydraulic valve to control operation of the work implement during the smooth mode or the abrupt mode. The mode control module comprises a smooth mode module and an abrupt mode module. The smooth mode module and the abrupt mode module are adapted to optimize movement of the work cycle during the smooth mode, and abrupt mode, respectively.

Abstract: A control system for a utility vehicle, particularly a compact utility tractor, that is speed-controlled by a hydrostatic transmission, prevents engine stalling by automatically reducing the stroke of a pump of the hydrostatic transmission, and thus reducing the vehicle speed, when the unloaded engine speed drops below a predetermined threshold. The apparatus includes a servo controlled hydrostatic transmission, an engine speed sensor, a throttle position sensor and a controller. The unloaded engine speed is determined by either an engine throttle lever position or by an engine speed capture algorithm that continuously monitors engine speed and records engine speed occurring when the transmission control pedals are positioned in neutral.

Abstract: A high-pressure and low-pressure selecting valve includes a valve body and a valve member movably provided in the valve body. The valve body has a pair of input ports, at least one output port, and a low-pressure port. The input ports, the output port, and the low-pressure port are so formed that when input to one of the input ports is of a higher hydraulic pressure, the valve member is moved by the pressure to connect the one input port to one of the output ports and the other input port to the low-pressure port. A swash-plate type hydraulic motor system selects, by means of this valve, high-pressure liquid necessary for controlling the swash plate and simultaneously connects the low-pressure relief valve to the low-pressure side of the system.

Abstract: A method is provided for controlling a torque output of an hydrostatic motor in fluid communication with a variable displacement pump. At least one of the motor and pump has variable displacement capabilities. The method includes monitoring at least one motor condition of the hydrostatic motor and determining a displacement signal corresponding to the monitored motor condition. The variable displacement capabilities are controlled based on the displacement signal to reduce a torque ripple in the torque output of the hydrostatic motor.

Abstract: In a direct drive type hydraulic pump, the displacement of the hydraulic pump is forcedly changed to a desired displacement according to an instruction of a channel different from a usual instruction, thereby changing to a desired displacement quickly with good responsivity. When an emergency brake switch is turned on, an emergency brake signal is entered an emergency brake control valve. Thus, an emergency brake signal pressure is entered a piston through an emergency brake signal oil passage, and a piston is forcedly positioned in a neutral position. In other words, the piston can be forcedly positioned in the neutral position according to the emergency brake signal regardless of the entry of a usual brake signal. Therefore, the displacement of the hydraulic pump can be forcedly changed to the neutral position (minimum displacement).

Abstract: A transmission for coupling a variable speed engine to a dynamoelectric machine that has three hydraulic units coupled to a mechanical summer, wherein two of the hydraulic units are varied in displacement to control the speed of the third in order to keep the speed of the dynamoelectric machine constant regardless of engine speed.

Abstract: The present invention includes a hydrostatic transmission system that has a control device that is selectable to send a speed signal to a motor for driving an output at a predetermined speed. A controller is used to automatically permit the selected speed signal in response to a predetermined speed signal and predetermined input from a sensing device indicating that the output is being driven in a forward drive condition. The controller is also used to automatically override the selected speed signal in response to a predetermined speed signal and predetermined input from a sensing device indicating that the output is being driven in a reverse drive condition. This invention allows for the speed of the motor to be changed from a high speed to a low speed when the motor is driving the output in a reverse drive condition to achieve greater efficiency and control of a work machine.