Abstract: A working machine includes a prime mover, a hydraulic pump driven by power of the prime mover, a cooler including a cooling fan rotated by either the power of the prime mover or hydraulic fluid delivered from the hydraulic pump, and a controller configured or programmed to perform a reduction control for reducing a target fan rotation speed that is a target rotation speed of the cooling fan in response to reduction of an actual prime mover rotation speed that is an actual rotation speed of the prime mover, and to perform, after the reduction control, a restoration control for restoring the target fan rotation speed. The controller is configured or programmed to make a difference between a reduction rate of the target fan rotation speed in the reduction control and an increase rate of the target fan rotation speed in the restoration control.

Abstract: In one aspect, a wireless transceiver is used to wirelessly connect various electrohydraulic components in a hydraulic system. In another aspect, a self-powered wireless hydraulic system includes a harvesting device for converting hydraulic energy into electrical energy. The electrical energy generated by the harvesting device can be used to power one or more electrohydraulic components and wireless transceivers. In another aspect, a self-powered wireless hydraulic system also includes a flow control device powered by the harvesting device for actively controlling the hydraulic flow through the harvesting device.

Abstract: Systems and methods for transitioning a hybrid vehicle from park or neutral to drive or reverse are presented. In one example, a requested engine speed is adjusted in response to a transmission disengaging indication and a transmission disengaging timer when a transmission is being disengaged from a gear. In another example, the requested engine speed is adjusted in response to a transmission engaging indication and a transmission engaging timer when the transmission is being engaged to a gear.

Abstract: Systems and methods for a heat engine system are described. In one embodiment, a system comprises a heat engine compressor, a heat exchanger, and a heat engine expander. The system comprises a partial state condenser in fluid communication with the heat engine expander. The partial state condenser includes a sense reservoir to hold the working fluid, a reservoir sensor to sense an electrical property of the working fluid, and a reservoir valve. The reservoir valve is in fluid communication with the sense reservoir, the heat engine compressor, and a heat engine condenser. The system comprises a processor to execute instructions to determine a specific energy of working fluid based on the electrical property of the working fluid and control the reservoir valve based on the specific energy to maintain a two-phase saturated state point within the partial state condenser based on the electrical property.

Abstract: A work machine includes a frame, a traction system supporting the frame, an implement system supported by the frame, and a hydraulic system. The hydraulic system includes a hydraulic oil tank, a control circuit, an oil cooler, and a cooler bypass valve assembly. The cooler bypass valve assembly is connected to the control circuit by a control circuit return line, and includes an unloading valve configured to allow hydraulic oil to flow from the control circuit return line to the hydraulic oil tank if a pressure of hydraulic oil in the control circuit return line exceeds a first threshold, a backpressure valve configured to allow hydraulic oil to flow from the return line to the oil cooler through an oil cooler inlet line if a pressure of hydraulic in the oil control circuit return line exceeds a second threshold, and an orifice configured to limit the flow of hydraulic oil through the backpressure valve.

Abstract: A hydraulic system includes a hydraulic circuit, a heater, a temperature sensor, and a controller. The hydraulic circuit includes a reservoir configured to store hydraulic fluid, a pump coupled to the reservoir, a driver positioned to drive the pump to pump the hydraulic fluid from the reservoir and throughout the hydraulic circuit, and an actuator positioned to selectively receive the hydraulic fluid from the pump to operate a controllable machine component. The driver is independent of a prime mover of the machine. The heater is positioned to facilitate selectively heating the hydraulic fluid. The temperature sensor is positioned to acquire temperature data indicative of a temperature of the hydraulic fluid. The controller is configured to monitor the temperature of the hydraulic fluid and selectively activate at least one of the heater or the pump to thermally regulate the hydraulic fluid to maintain the hydraulic fluid within a target temperature range.

Abstract: A variable ratio hydraulic steering device with two or more orbit displacers ensures steering with low actuating forces even in the event of a total or partial failure of the oil flow supply. In the event of a total or partial failure of the oil flow supply, the device is capable of switching from one orbit displacer to another, if necessary, independently of the pressure at the inlet connection of the steering device.

Abstract: A continuously variable transmission includes an electric oil pump disposed in an oil passage between primary and secondary pulley oil chambers. An oil passage switching valve is disposed between the oil pump and the primary pulley oil chamber. The oil passage switching valve switches between a first switching position in which the primary pulley oil chamber and the oil pump are connected, and a second switching position in which the primary pulley oil chamber and the oil pump are disconnected and in which the oil pump and an oil passage connecting an oil reservoir and the oil passage switching valve are connected. In addition, the continuously variable transmission includes a discharge mechanism having a leak valve disposed in the oil passage between the electric oil pump and the oil passage switching valve for discharging oil that is discharged from the oil pump towards the primary pulley oil chamber.

Abstract: A hydraulic system includes an output fluid tube connected to a hydraulic pump to output operation fluid, and an unload valve to be switched to output operation fluid or to stop outputting operation fluid, the unload valve being connected to the output fluid tube. The hydraulic system includes a hydraulic actuator to be actuated by operation fluid, a control valve to control operation fluid to be supplied to the hydraulic actuator with use of a pilot fluid that is operation fluid applied to a pressure-receiving portion of the control valve, a pilot fluid tube connected to the pressure-receiving portion of the control valve, an operation valve to change a pressure of the pilot fluid to be applied to the pilot fluid tube, and a warm-up fluid tube connected between the unload valve and the pilot fluid tube.

Abstract: A parking lock actuation system for an automatic gearbox of a vehicle is described. The parking lock actuation system has a closed state in which a piston rod of a hydraulic cylinder is in a first position urging a locking pawl to block a gear of the automatic gearbox, and an open state in which the piston rod of the hydraulic cylinder is in a second position preventing the locking pawl from engaging the gear of the automatic gearbox. The parking lock actuation system further includes a first hydraulic valve being connected to a first hydraulic line, to a pressure source and a substantially non-pressurized reservoir, and a second hydraulic valve being connected to a first volume of the hydraulic cylinder, to the first hydraulic line and a non-pressurized reservoir. The first hydraulic valve includes an electrical actuator.

Abstract: A method for actuating a valve device as a function of a characteristic curve including actuating the valve device with a dither superimposed on a target value (i_EDS) with such a frequency that the operating condition of the valve device follows the actuation corresponding to the characteristic curve (v_kk). The method further includes determining, with the characteristic curve (v_kk), the output values (“1”, x) which correlate with the target values (i_EDS) at inflection points of a harmonic oscillation impressed upon the valve device with the dither, and determining further output values as a function of the output values (“1”, x). The amplitude of the dither is predefined such that, during an actuation of the valve device, one of the inflection points lies in a first or second characteristic curve range (v_kk1 or v_kk3, v_kk3 or v_kk5), and another inflection point lies in a third characteristic curve range (v_kk2 or v_kk4).

Abstract: A hydraulic system of a work machine includes a first oil path which is connected to a hydraulic pump and though which hydraulic oil is to flow from the hydraulic pump. An operation valve is connected to the first oil path. An operation lever is to control the operation valve to control pressure of the hydraulic oil in accordance with an operation of the operation member. A hydraulic instrument is to be actuated by the hydraulic oil output from the operation valve. A second oil path connects the operation valve and the hydraulic instrument. The hydraulic oil in the second oil path is discharged through a discharge oil path. An actuation valve is provided in the discharge oil path. An actuation valve controller is to control the actuation valve to be opened and closed according to a temperature of hydraulic oil detected by a first sensor.

Abstract: A monitoring system for monitoring fluid parameters in a lubrication system of an engine may include an input conduit configured to be in fluid communication with the lubrication system at a first location upstream of an oil cooler of the lubrication system. A monitoring device may be in fluid communication with the input conduit. An output conduit may be in fluid communication with the lubrication system at a second location downstream of the oil cooler. The output conduit may include a flow restrictor configured to provide a desired pressure and flow of a fluid to the monitoring device via the input conduit.

Abstract: A torque converter clutch (TCC) release fluid lubrication system for a motor vehicle transmission includes a first fluid line, a second fluid line and a third fluid line. The first fluid line supplies TCC apply fluid to the TCC. The second fluid line receives TCC release fluid from the TCC. And the third fluid line supplies a first lubrication fluid to the transmission. The TCC release fluid and the first lubrication fluid combine into a second lubrication fluid that is fed into the transmission.

Abstract: A construction machine is provided which is capable of warming up without an additional hydraulic device. A hydraulic excavator includes a cooling oil line connected to an arm control valve for leading hydraulic oil discharged from the arm control valve to a tank through an oil cooler when the arm control valve is shifted to an extension position, and a non-cooling oil line connected to the arm control valve for leading hydraulic fluid discharged from the arm control valve to the tank running away from the oil cooler when the arm control valve is shifted to a neutral position. The arm control valve includes a guide passage provided at the neutral position for leading hydraulic fluid discharged from a hydraulic pump to the non-cooling oil line.

Abstract: A hydraulic system for a transmission device includes a primary pressure circuit and a secondary pressure circuit suppliable with hydraulic fluid from a defined saturation condition of the primary pressure circuit. A converter lock-up clutch is subjected to an operating pressure by a converter clutch valve. An inner torus chamber is suppliable with hydraulic fluid at a converter pressure of the secondary pressure circuit by a converter switching valve and by a valve device and a throttle device of the primary pressure circuit. The throttle device of the primary pressure circuit is downstream of the valve device of the primary pressure circuit.

Abstract: A hydraulic system for a construction machine having a protection device is disclosed, which can limit a flow rate of hydraulic fluid that is discharged from a hydraulic pump in accordance with a hydraulic fluid temperature and notify an operator of information on the hydraulic fluid temperature.

Abstract: A fluid intake/discharge valve body for suction of a cryogenic liquefied gas fluid into a cylinder liner and discharge of the gas fluid with a piston, includes: a valve seat body including a fluid supply portion to supply the fluid and a fluid exhaust portion; an intake valve biased against the fluid supply portion; and a discharge valve biased against the fluid exhaust portion. The fluid supply portion includes a supply pathway connected to a supply pipe; a dividing wall including intake holes facing the intake valve; and a counterbore recessed portion on the dividing wall to surround the intake holes. The intake valve abuts an edge of the recessed portion when biased against the fluid supply portion. The discharge valve receives fluid pressure from a side of the discharge hole including a recessed portion disposed in a region wider than an outer periphery of the discharge hole.

Abstract: A hydrostatic drive, especially a hydrostatic fan drive, includes a hydraulic constant-displacement pump configured to drive a hydraulic motor for a fan. The drive further includes a hydraulic machine configured to supply a second hydraulic circuit with a pressure medium. The constant-displacement pump is configured to be hydraulically combined with the hydraulic machine.

Abstract: A multi-mode power train and multi-mode vehicle include a A power-conversion device that is in communication with an engine via a direct mechanical power-transfer connection extending from the engine to the power-conversion device. A continuously variable power source (CVP) is in communication with the power conversion device via an intermediate power-transfer connection. A lock-up device with first and second engagement states is provided between the engine and the power-conversion device or the CVP. With the lock-up device in the first engagement state, mechanical power from the engine is converted by the power-conversion device for use by the CVP, with the CVP using the converted power to provide mechanical power to a power-output connection. With the lock-up device in the second engagement state, the engine transmits mechanical power through the lock-up device to the power-output connection.

Abstract: The invention concerns a hydrodynamic coupling, having a pump wheel and a turbine wheel, which form together a toroidal working chamber which can be filled with working medium; with a closed working medium circuit, which extends from the working chamber via a working chamber outlet, an external circuit branch and a working chamber inlet back into the working chamber; with a storage chamber positioned outside the working chamber and outside the closed working medium circuit, for receiving the working medium evacuated from the working chamber for reducing the filling level of the working chamber, which is connected via a connection for conveying the working medium outside the working chamber to the closed working medium circuit. The invention is characterized in that the storage chamber is designed as a confined chamber which is pressure-tight to the environment, having a control pressure port so as to forcibly displace the working medium in the storage chamber with a control pressure.

Abstract: A pipelayer includes a pilot pressure control unit. The pilot pressure control unit supplies hydraulic fluid to a pilot port of a warm-up control valve so that the warm-up control valve enters an open state when a winch control valve is in the closed state. The pilot pressure control unit drains hydraulic fluid from the pilot port of the warm-up control valve so that the warm-up control valve enters the closed state when the winch control valve is in the open state. The stroke amount from the stroke end of the closed side of the spool of the warm-up control valve when the meter-out opening of the warm-up control valve is fully closed is larger than the stroke amount from the stroke end of the closed side of the spool of the winch control valve when the meter-in opening of the winch control valve is fully closed.

Abstract: Provided is an apparatus for driving a boom of a construction machine, allowing required power to be reduced.

Abstract: An electro-hydraulic actuator (EHA) includes a hydraulic circuit having a plurality of pressure compensated flow control valves for limiting the maximum flow rate through the fluid conduits regardless of the loads imparted on the actuator. In one embodiment of the EHA, a plurality of combination manual override/thermal expansion valves that simplify the manufacture of the EHA.

Abstract: The present invention relates to an implement, in particular an excavator or machine for material handling, with an element movable via at least one working drive, wherein at least one energy recovery cylinder is provided for energy recovery from the movement of the movable element, which includes a chamber filled with gas, wherein the actuation of the implement is effected in dependence on the directly or indirectly determined temperature of the gas in the chamber filled with gas.

Abstract: A power generation apparatus, a power generation method, a decomposition-gas boiler, and a decomposition-gas turbine with which nitrous oxide may be used as an environmentally friendly energy source. A fuel gas including nitrous oxide (N2O) is supplied to a decomposition reactor (22) in which a catalyst (21) for decomposing nitrous oxide is disposed. Steam is generated by a decomposition-gas boiler by heat recovery from decomposition gas (N2, O2) generated by decomposing the nitrous oxide, the steam generated by the decomposition-gas boiler is used to drive the rotation of a steam turbine to obtain motive power, and the motive power is subsequently used to drive a generator to obtain electrical power. Alternatively, the decomposition gas (N2, O2) generated by decomposing the nitrous oxide is used to drive the rotation of a decomposition-gas turbine to obtain motive power.

Abstract: A warm-up pilot pressure control unit adjusts pilot pressure inputted to a first flow channel open/close unit so that the flow channel open/close unit is switched to an open state when a warm-up start state is entered under the necessary condition that a first winch operation member is in a neutral position. When the first flow channel open/close unit is in the open state, a first pump displacement adjustment unit adjusts the displacement of a first hydraulic pump so that the differential pressure between a first pump hydraulic circuit and a first warm-up hydraulic circuit becomes constant at a predetermined set pressure.

Abstract: A rotational system is provided for controlling rotation of one or more solar collectors to track the movement of the sun, to automatically keep the collectors locked in stow position during high wind conditions, and advantageously also to prevent damage to the rotational system due to high pressures caused by high temperature conditions. The system utilizes a bi-directional hydraulic rotational actuator hydraulically connected to a control system. The actuator advantageously includes a system of helical gears and a piston, and the control system includes hydraulic lines equipped with check valves that prevent circulation of hydraulic fluid through the hydraulic lines and the actuator when backpressure is exerted in one of the hydraulic lines as a result of high wind force on the collectors. In addition, the control system advantageously comprises a pressure-relief system to prevent damage to the actuator during high temperature conditions.

Abstract: Parasitic hydraulic loading on an engine is significantly reduced during cold starts by using an unloader valve to divert the flow of hydraulic fluid from a hydraulic pump to a hydraulic actuator, i.e., load source, recirculating the hydraulic fluid between the hydraulic pump and the unloader valve.

Abstract: A pipelayer includes a pilot pressure control unit. The pilot pressure control unit supplies hydraulic fluid to a pilot port of a warm-up control valve so that the warm-up control valve enters an open state when a winch control valve is in the closed state. The pilot pressure control unit drains hydraulic fluid from the pilot port of the warm-up control valve so that the warm-up control valve enters the closed state when the winch control valve is in the open state. The stroke amount from the stroke end of the closed side of the spool of the warm-up control valve when the meter-out opening of the warm-up control valve is fully closed is larger than the stroke amount from the stroke end of the closed side of the spool of the winch control valve when the meter-in opening of the winch control valve is fully closed.

Abstract: A hybrid drive device including an electric motor; an automatic transmission; a lubricating oil passage to which a lubricating oil pressure is supplied; and a switching valve that is switched between a first state where the lubricating oil passage communicates with a first lubricating oil passage that guides lubricating oil to the automatic transmission, and a second state where the lubricating oil passage communicates with a second lubricating oil passage that guides the lubricating oil to the electric motor. The electric motor and an internal combustion engine output shaft are operable in conjunction with the automatic transmission. The switching valve is switched from the first state to the second state when a vehicle is in a stationary state or running at a speed of a predetermined value or less including the stationary state of the vehicle.

Abstract: A hydraulic control system for an automatic transmission. The hydraulic control system is applied to an automatic transmission adapted to vary a torque capacity of a transmission member by an actuator. The hydraulic control system includes: a discharging device configured to discharge compressible gas entrained in the hydraulic fluid in the actuator; an interrupting device that interrupts power transmission; and a controller configured to determine an entrainment of the compressible gas in the hydraulic fluid, disconnect the power transmission via the interrupting device in a case that an entrained compressible gas is determined, and cause the entrained compressible gas to be removed from the hydraulic fluid by rotating the actuator while interrupting the power transmission.

Abstract: To regenerate a compressed air supply device of a commercial vehicle, a first compressed air circuit is supplied with compressed air until reaches a predetermined target pressure value; then a second compressed air circuit is supplied. Between these steps, the method: (1) regenerates an air dryer when the pressure in the first compressed air circuit has reached the target pressure value, and when a moisture value of the air dryer exceeds a predetermined target moisture value; (2) terminates the regeneration when the pressure has dropped to a predetermined limit pressure value or the moisture value of the air dryer has reached or dropped below the target moisture value; (3) supplies the first compressed air circuit until it has reached the predetermined target pressure value; and (4) repeats the preceding intermediate steps when the moisture value is greater than the target moisture value.

Abstract: Interventionless setting assemblies and associated methods are disclosed. A method of setting downhole equipment comprises applying a pressure to a compensating volume and providing a working volume, wherein the working volume is separated from the compensating volume by one or more hydraulic control devices. A pressure is applied to the working volume in response to the pressure applied to the compensating volume. The pressure applied to the compensating volume is then reduced and the pressure applied to the working volume is captured by maintaining the pressure applied to the working volume when the pressure applied to the compensating volume is reduced. The captured pressure in the working volume is applied to set downhole equipment.

Abstract: A hydraulic oil supply device includes: a work equipment pump that supplies a hydraulic oil to a hydraulic actuator that drives a work equipment; a fan pump that supplies the hydraulic oil to a hydraulic motor that drives a cooling fan; and a circuit switching valve provided on a hydraulic circuit being branched from a hydraulic circuit connecting the hydraulic actuator with the work equipment pump to be connected to the fan pump, the circuit switching valve selectively connecting a discharge portion of the fan pump to the hydraulic actuator and the hydraulic motor.

Abstract: The present invention provides a cooling system such as employed in cooling a heat source and a transmission system having said cooling system integrated therewith. The cooling system further includes a pump for supplying hydraulic fluid under pressure to a motor for driving a fan employed in the cooling process. In operation, a controller initiates operation of the pump such as to supply hydraulic fluid to said motor only when needed, thereby to improve the efficiency and controllability of the cooling system.

Abstract: The invention reduces waste of flow volume of pressurized oil discharged from a hydraulic pump when the rotational speed of a cooling fan is increased to the target rotational speed. The target rotational speed of the cooling fan is set at a target rotational speed setting portion. An acceleration pattern for increasing the cooling fan to the target rotational speed is set at an acceleration pattern setting portion based on the rotational speed of the cooling fan, the target rotational speed set at the target rotational speed setting portion, and magnitude of force due to inertia of the cooling fan and the hydraulic motor. The rotational speed command value calculation portion controls the pressurized oil to be supplied to the hydraulic motor at a flow rate required. Thus, it is possible to reduce wasted relief flow volume.

Abstract: A protection valve for a hydraulic drive system and a method for protecting the hydraulic drive system and pumping equipment driven by the hydraulic drive system includes a valve body, an actuator shaft movably disposed within the valve body, a thermal actuator for displacing the actuator shaft between an un-actuated position and an actuated position, and a poppet attached to the actuator shaft for movement therewith. The thermal actuator is configured to displace the actuator shaft between the un-actuated position and the actuated position in response to a hydraulic oil temperature that exceeds a predetermined maximum. A thermal actuator body is rigidly attached to the valve body at one end and a valve seat body is rigidly attached to the valve body at the other end. The thermal actuator body has openings formed therein for placing hydraulic oil in fluid communication with the thermal actuator.

Abstract: In one aspect, a hydraulic system including a reservoir, a hydraulic device, a first sensor, a second sensor and a controller is described. The reservoir is connected to the hydraulic device for supplying hydraulic fluid to and from the hydraulic device. The first sensor is adapted for measuring a first volume of the hydraulic fluid in the reservoir. The second sensor is connected to the hydraulic device such that at least one parameter being indicative for a second volume of the hydraulic fluid in the hydraulic device is measurable. The controller is adapted for calculating the second volume of the hydraulic fluid based on the at least one parameter. The controller is adapted for determining a leakage of hydraulic fluid in the hydraulic system based on the first volume and the second volume.

Abstract: An object of the present invention is to provide a gas turbine control device which is capable of performing correction on the basis of a fuel composition of fuel gas to be supplied to a gas turbine, and is capable of changing an amount of correction in response to variation with time of the gas turbine. To attain this, a frequency analyzing unit 25 performs a frequency analysis of combustion oscillation of a combustor and splits a result of the analysis into respective frequency bands. Then, a state grasping unit 22 checks an operating state of the gas turbine on the basis of the result of the analysis of the combustion oscillation and process value of the gas turbine, and corrects the checked operating state on the basis of a fuel composition or a heat capacity of fuel gas measured by a fuel characteristic measuring unit 200. A countermeasure determining unit 23 conducts a countermeasure for controlling an operating action of the gas turbine on the basis of the operating state thus checked.

Abstract: A hydraulic drive and method for controlling such a drive includes two drive motors configured to be controlled by at least one continuously adjustable distribution valve. The two drive motors are configured as adjustable hydraulic machines.

Abstract: A hydraulic actuation system includes a metering valve; and a piston arrangement hydraulically in parallel with the metering valve, the system configured to preferentially move the piston to precharge an end device with hydraulic fluid prior to supplying an actuation fluid volume to the end device and method for actuating a hydraulic end device.

Abstract: The invention relates to a system for regulating a temperature of hydraulic fluid in at least one hydraulic circuit of an aircraft, wherein, in a periphery of the aircraft, additional hydraulic consumption units are each provided with at least one controllable valve for heating the hydraulic fluid above an adjustable minimum temperature limit value (Tmin), wherein the controllable valve is closed during a maneuver of the aircraft, wherein the controllable valves of the additional hydraulic consumption units are closed when the temperature of the hydraulic fluid exceeds an adjustable theoretical temperature value (Tsoll), and wherein a temperature control system is connected to a temperature sensor for adjusting the controllable valve on the basis of a local temperature of the hydraulic fluid, the temperature sensor being near the hydraulic consumption units which are arranged in wings and tail of the aircraft.

Abstract: Disclosed is a control device of a hydraulically driven fan. The control device of a hydraulically driven fan is characterized by comprising first command value calculation means for calculating a fan speed command by a proportional term only while a difference between a target valve controlled variable and an actual valve controlled variable is not smaller than a predetermined threshold, second command value calculation means for calculating a fan speed command by the proportional term and an integral term while a difference between a target valve controlled variable and an actual valve controlled variable is smaller than a predetermined threshold, target valve controlled variable calculation means for calculating a target valve controlled variable of a control valve based on the calculated fan speed command, and control means for outputting a valve controlled variable to a control valve such that the control valve reaches the target valve controlled variable.

Abstract: The invention relates to a hydraulic drive (2) having a main pump (8), which can be adjusted in terms of delivery volume and delivery direction, and having a hydraulic motor (9), which main pump (8) and hydraulic motor (9) are connected to one another in a closed circuit via pressure lines (10A, 10B), and having a charge pump (14, 15) for charging into the closed circuit and for supplying pressurized fluid to at least one controlling device (11, 12), wherein the charge pump (15) has a separate drive motor (19) whose power/rotational speed can be specified independently of the rotational speed of the drive (3) of the main pump (8). In this way, the charge pump (15) can be of smaller dimensions than previously conventional, and the power balance of the hydraulic drive can be improved.

Abstract: A pump torque control system is capable of preventing hunting due to interference between speed sensing control and control of an engine speed of a prime mover when the temperature of a hydraulic fluid is low. A maximum absorption torque is set in a regulator 31 that controls displacement volumes of hydraulic pumps 2 and 3 based on a deviation between target and actual engine speeds of a prime mover 1. A second modification factor calculating section 45 and a control gain modifying section 49, which are included in a controller 23 that performs speed sensing control to ensure that the maximum absorption torque of the hydraulic pumps 2 and 3 is reduced, change a control gain of the speed sensing control based on a value detected by the hydraulic temperature sensor 34 to ensure that the control gain is reduced as the temperature of the hydraulic fluid is reduced.

Abstract: A hydraulic control system for a powertrain includes a sump for storing a hydraulic fluid and a pump having an inlet in communication with the sump and an outlet. A valve system is in communication with the outlet of the pump. An accumulator for storing and releasing the hydraulic fluid is in communication with the inlet of the pump and with the valve system. A first control device is disposed between the accumulator and the valve system. A second control device is disposed between the accumulator and the inlet of the pump. The accumulator is charged with the hydraulic fluid when the pump is powered, the accumulator stores the hydraulic fluid when the first control device and the second control device are in the closed condition, and the accumulator releases the hydraulic fluid and primes the pump when the second control device is in the open condition.

Abstract: A hydraulic system with thermal shock protection. The hydraulic system can include a controller that limits when hot hydraulic fluids may be directed to cold hydraulic components. The hydraulic system can be used in machines such as trenchers to protect hydraulic components such as hydraulic motors from failure due to thermal shock.

Abstract: In a module system for manufacturing variants of two and three stable positions fluid-operated actuators a cylinder housing of both variants of two and three stable positions actuators is manufactured from a blank. The blank includes at least one opening for a cover and is identical for the variants of the two and three stable position actuator, and is at least prepared for the arrangement of a first pressure duct, a second pressure duct, and a first cylinder diameter of the cylinder housing.

Abstract: A device for varying the stroke of first and second hydraulic machines. At least one piston is functionally connected to axes of the hydraulic machines. Depending on power demanded by a driver, the piston can be acted upon, via position and high pressure control valve units of a valve system, with pressures that correspond to a pressure present in the hydraulic machines and that act in a first adjustment direction of the hydraulic machines axes. Pressure in the hydraulic machines is controlled by the position control valve unit and is limited by the high pressure control valve unit. The piston can be acted upon by the valve system with pressures that correspond to the pressure present in the hydraulic machines and that act in a second adjustment direction of the axes of the hydraulic machines, and action of the position control valve unit can be reversed.