Abstract: A latching actuator capable of repeated operation in a cryogenic, remote, or difficult-to-access environment, capable of enduring many cycles without user intervention or maintenance, capable of latching in a fixed position without consuming additional power, or to operate independent of external environmental conditions. In selected embodiments, a latching actuator may comprise an expansion chamber that houses a working substance capable of undergoing a phase change, a logic mechanism, a biasing assembly, and an output pin. In one embodiment, a wax motor may provide the motive force to toggle a latching mechanism. An actuator may be capable of positioning an output pin in two or more discrete latching positions and may be used to create a thermal connection between two structures, to engage or disengage a clutch, or to position an optical element in an optical instrument. An actuator may also be used as a launch lock apparatus.

Abstract: A control system for a machine is disclosed. The control system may have a pump, a low pressure reservoir, and at least one actuator connected to receive fluid pressurized by the pump and discharge fluid to the low pressure reservoir. The control system may also have a bypass passage situated to allow fluid to bypass the at least one actuator, and a warmup valve disposed within the bypass passage and being movable between a flow-passing position and a flow-blocking position. The control system may further have a hydraulic temperature sensor configured to generate a signal indicative of a temperature of the fluid, and a controller in communication with the pump, the warmup valve, and the hydraulic temperature sensor. The controller may be configured to move the warmup valve to the flow-passing position, fix a displacement position of the pump, and adjust an input speed of the pump in response to the signal.

Abstract: A control unit for controlling a flow rate control valve includes a first computing unit for determining an energy component that heats hydraulic oil, a first setting unit for setting a second relationship between a flow rate through an oil cooler and the energy component based on an experimentally or empirically known, first relationship between flow rate through the oil cooler and an amount of oil cooler heat radiation as derived by replacing the amount of oil cooler heat radiation in the first relationship to the energy component, and a second computing unit for determining the flow rate through the oil cooler based on the energy component determined by the first computing unit and the second relationship. The control unit controls the flow rate control valve according to the flow rate determined by the second computing unit.

Abstract: A compressed air supply system for a utility vehicle includes a compressor that can be driven by a drive by a pneumatic clutch, and a valve that can be actuated by an electrical signal for the selective supply of compressed air to a control input of the clutch. The electrical signal is provided by an electronic control system to which signals indicating an operating state of a compressed air preparation system and various vehicle states can be supplied.

Abstract: A work vehicle includes a fluid circuit to operate at least one implement for performing work, the fluid circuit having at least a first operating mode and a second operating mode. The first operating mode is configured to operate within a first predetermined flow rate range within a first predetermined fluid pressure level range. The second operating mode is configured to operate within a second predetermined flow rate range and within a second predetermined fluid pressure level range. In response to the fluid circuit operating within the second operating mode, a maximum pressure value of the second predetermined fluid pressure level range is greater than a maximum pressure value of the first predetermined fluid pressure level range, and a maximum value of the second predetermined flow level range is less than a maximum value of the first predetermined flow level range.

Abstract: A compressed-air energy storage system according to embodiments of the present invention comprises a reversible mechanism to compress and expand air, one or more compressed air storage tanks, a control system, one or more heat exchangers, and, in certain embodiments of the invention, a motor-generator. The reversible air compressor-expander uses mechanical power to compress air (when it is acting as a compressor) and converts the energy stored in compressed air to mechanical power (when it is acting as an expander). In certain embodiments, the compressor-expander comprises one or more stages, each stage consisting of pressure vessel (the “pressure cell”) partially filled with water or other liquid. In some embodiments, the pressure vessel communicates with one or more cylinder devices to exchange air and liquid with the cylinder chamber(s) thereof. Suitable valving allows air to enter and leave the pressure cell and cylinder device, if present, under electronic control.

Abstract: A working fluid cooling control system has a controller 100 that receives inputs signals from a traveling motor speed pickup 101, a pressure sensor 102, a signal receiving line 103a of an option selecting switch 103 and a temperature sensor 104. The controller performs predetermined arithmetic processing and controls proportional solenoid valves 105 and 106. The pressures controlled by the solenoid valves are compared with positive control command pressures in shuttle valves 109 and 110. In this way, in the case of an operation pattern corresponding to a rise in temperature of the working fluid, minimum tilting angles of hydraulic pumps 11 and 12 are increased to increase an average flow rate of the working fluid passing through an oil cooler 40, thereby increasing an average heat discharge amount and reducing an equilibrium temperature of the working fluid.

Abstract: A compressed-air energy storage system according to embodiments of the present invention comprises a reversible mechanism to compress and expand air, one or more compressed air storage tanks, a control system, one or more heat exchangers, and, in certain embodiments of the invention, a motor-generator. The reversible air compressor-expander uses mechanical power to compress air (when it is acting as a compressor) and converts the energy stored in compressed air to mechanical power (when it is acting as an expander). In certain embodiments, the compressor-expander comprises one or more stages, each stage consisting of pressure vessel (the “pressure cell”) partially filled with water or other liquid. In some embodiments, the pressure vessel communicates with one or more cylinder devices to exchange air and liquid with the cylinder chamber(s) thereof. Suitable valving allows air to enter and leave the pressure cell and cylinder device, if present, under electronic control.

Abstract: A hydraulically driven industrial machine having a variable displacement type hydraulic pump adapted to take in and pressurized working oil from an working oil tank, a hydraulic actuator to be driven by pressurized working oil delivered from the hydraulic pump through a control valve to perform a predetermined job, a variable return oil cooling means capable of cooling return oil from the hydraulic actuator at a varying cooling rate, an operational load detection means adapted to detect an operational load factor of the hydraulic actuator, and a control means adapted to vary the return oil cooling rate on the basis of an operational load factor detected by the operational load detection means.

Abstract: A torque converter coupled to a transmission has a torque converter operating mode and a lockup operating mode. A first pump may be configured to supply transmission fluid to a plurality of electro-hydraulic transmission components. A second pump may be configured to supply transmission fluid to a lubrication system of the transmission. A valve may be configured to route transmission fluid supplied by the second pump through the torque converter during the torque converter operating mode. Means may also be provided for selectively routing at least some of the transmission fluid supplied by the first pump through the torque converter. Illustratively, transmission fluid supplied by the first pump may, but need not, be routed to the torque converter only during the torque converter operating mode or only during the torque converter operating mode if the temperature of transmission fluid exiting the torque converter exceeds a threshold temperature.

Abstract: A dynamic support system includes a control system for controlling inflation and deflation of at least one actuator having an inlet connectable to the a control unit of the dynamic support system. The control unit may be in communication with a sensor and may control inflation and deflation of the at least one actuator in response to information provided by the sensor.

Abstract: A hydraulic circuit for heavy equipment is disclosed, which utilizes a hydraulic fluid supplied from a hydraulic pump for driving a cooling fan, as a pilot signal pressure, without installing a separate constant displacement pilot pump for supplying the pilot signal pressure to a control valve for controlling the hydraulic fluid to be supplied to a working device such as a boom.

Abstract: A compressed air supply device is provided for a utility vehicle, having a compressor which can be driven by a drive via a pneumatically switchable clutch, and a valve which can be activated by an electrical signal in order to optionally feed compressed air to a switching inlet of the clutch. The compressed air, which is fed to the switching inlet via the valve, is extracted from a compressed air preprocessing system via a non-return valve.

Abstract: A hydraulic system includes a hydrostatic piston machine having a plurality of valves that can be actuated using an actuator depending on the motion of the pistons and a control unit for activating the actuators. The switching points at which the valves are actuated are dependent on operating conditions, so that the expected functionality and the essential properties of the hydrostatic piston machine are ensured under different operating conditions.

Abstract: A motor vehicle power take off system for a motor vehicle engine includes a viscous coupling. The input rotor of the viscous coupling is provided with a variable geometry impeller section which allows direct control over the proportion of input torque on the input shaft transferred to the viscous fluid and thereby to an output shaft. Both passive and active control schemes are proposed.

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 pressure control apparatus for a torque converter includes a relay valve switching levels of a hydraulic pressure in the hydraulic power transmission chamber and establishing selective connections between a cooler and the hydraulic power transmission chamber or between the cooler and a hydraulic pressure supply source of which a flow amount of the operational fluid is regulated by a first orifice, an electronic control unit controlling operations of the relay valve, a hydraulic pressure declination determining portion judging whether the hydraulic pressure of the hydraulic pressure supply source is lower than a threshold value based on a predetermined vehicle state, and a switching command outputting portion outputting a command to connect the cooler and the hydraulic pressure supply source by the relay valve when the hydraulic pressure declination determining portion determines that the hydraulic pressure of the hydraulic pressure supply source is lower than the threshold value.

Abstract: In a self-propelled machine F for processing paving material, the machine having a liquid cooled combustion engine M and at least one hydraulic circuit H containing hydraulic pumps 6, hydromotors or hydrostatic drive units 7-10 and at least one hydraulic medium reservoir 12, a fan assisted cooling device K including cooling regions 1b, 1c at least for the cooling liquid of the combustion engine M and of the hydraulic medium of the hydraulic circuit H. A hydraulic medium operation temperature setting and regulating device R is provided for the hydraulic medium cooling region 1c constituted by a separate cooler 24 in order to generate an operation temperature T of the hydraulic medium above at least about 60° C. and to maintain this operation temperature depending on the hydraulic load situation in the hydraulic liquid H and on the surrounding climate, independently from a cooling regulating system S for the combustion engine M.

Abstract: Systems and methods of controlling automatic transmission fluid (ATF) in a vehicle include torque converter systems generally having a pump, a turbine and a stator. The stator is selectively rotated during periods of predetermined low ATF temperature, thereby causing temporarily induced inefficiencies that warm the ATF.

Abstract: A hydraulic control system in which a pump for pressurized hydraulic fluid connects with a valve assembly having a valve element displaceable in a chamber to selectively direct fluid to a load driven by the hydraulic system. Surfaces on the end faces of the valve element are exposed to hydraulic pressure from a controller via electro-hydraulic solenoid valves. The surfaces of the valve element adjacent the end faces are undercut to establish a leakage flow path and the solenoid valves are selectively actuated to pressurize the end faces to a level below normal actuation of the valve element but high enough to cause fluid to return to a drain and thus increase the temperature of the hydraulic fluid in the system.

Abstract: A method is provided for controlling and/or regulating the air pressure in a compressed air supply device for a utility vehicle. At least one pressure value in the compressed air supply device and/or in vehicle components connected to the compressed air supply device is recorded. A humidity value representing the humidity content in an air filter unit associated with the compressed air supply device is determined. A clutch connecting a drive to a compressor is opened. A discharge valve of the compressed air supply device is opened when the pressure value is above a predetermined minimum value and the humidity value exceeds a predetermined threshold value. The clutch is opened and the discharge valve remains closed when it is indicated that the clutch can be engaged, the pressure value reaches a predetermined cutting-off pressure, and the humidity value is below the predetermined threshold value.

Abstract: A servo system includes pressurized fluid, and one or more fluid control devices (FCD) such as a valve or actuator, with at least one FCD having an element with a variable property that varies in response to a stimulus. The FCD controls a flow rate or pressure transmission of the fluid within the servo system. The element may include an active return spring having a variable stiffness. The servo system may operate as an interlock system for a transmission. A method for moving an output load using a servo system includes providing a first FCD with an active element, connecting an output load to a second FCD, activating the active element with a stimulus to vary a property of the active element, transmitting a force from the pressurized fluid to the second FCD, and moving the output load from a first position to a second position in response to the force.

Abstract: The present invention is directed generally to a system and method which employ a compressed gas-driven device with a passive thermodynamic composition. Certain embodiments provide a compressed gas-driven (e.g., CO2-driven) device implementation that includes a passive thermodynamic composition which allows for extended use of the device without freezing and without requiring a persistently-maintained, active (e.g., electrically-powered) heating. Further, certain embodiments provide a compressed gas-driven (e.g., CO2-driven) device implementation that includes a passive thermodynamic composition which allows for extended use of the device without freezing and without requiring an ignition heat source (e.g., electrically-powered or pyrotechnic as generator) for heating the device.

Abstract: A hydraulic drive system for storing and releasing hydraulic fluid includes a high pressure storage device, a low pressure storage device, and a pump-motor operating at a range of pump-motor speeds for converting between hydraulic energy and mechanical energy. The pump-motor is disposed between the high pressure device and the low pressure device. In normal operation, the hydraulic drive system enters a motoring mode where hydraulic energy is released from the high pressure storage device and converted to mechanical energy using the pump-motor. It also enters a pumping mode where mechanical energy is converted into hydraulic energy. A neutral state exists where hydraulic energy is neither stored nor released from the high pressure storage device. An approach for compensating for temperature changes using varying pressure limits helps to maintain the hydraulic drive system in normal operation, thereby promoting efficiency within the hydraulic drive system.

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 method and system of controlling an engine torque of an automatic transmission calculate a current oil temperature in a torque converter and restrict an engine torque based on the calculated current oil temperature if the torque converter is determined to be in a stall state. The method may include detecting vehicle information; determining whether a stall condition is satisfied; calculating, if the stall condition is satisfied, a current oil temperature in a torque converter; comparing the current oil temperature to a predetermined temperature; and controlling the engine torque when the current oil temperature is higher than or equal to the predetermined temperature.

Abstract: A control system for a machine is disclosed. The control system may have a pump, a low pressure reservoir, and at least one actuator connected to receive fluid pressurized by the pump and discharge fluid to the low pressure reservoir. The control system may also have a bypass passage situated to allow fluid to bypass the at least one actuator, and a warmup valve disposed within the bypass passage and being movable between a flow-passing position and a flow-blocking position. The control system may further have a hydraulic temperature sensor configured to generate a signal indicative of a temperature of the fluid, and a controller in communication with the pump, the warmup valve, and the hydraulic temperature sensor. The controller may be configured to move the warmup valve to the flow-passing position, fix a displacement position of the pump, and adjust an input speed of the pump in response to the signal.

Abstract: A method and a system for determining a setting parameter of a hydrostatic displacement unit is provided. In the method, a pressure value, a rotational speed value, and a torque value are determined. The setting parameter can be determined with use of the pressure value, rotational speed value, torque value of the setting parameter characteristic diagram, and a setting parameter characteristic diagram, which is an inverted efficiency characteristic diagram, which has at least pressure, rotational speed, and torque as input parameters.

Abstract: A hydraulic unit including an integrated fluid cooler. The fluid cooler includes a flow-through type heat exchanger. The hydraulic unit can include a pump, a motor, or both a pump and a motor. The fluid cooler can be carried by a housing of the hydraulic unit and a fan for moving air through the fluid cooler and circulating air over at least a portion of the housing of the hydraulic unit can be interposed between the fluid cooler and the housing. The fluid cooler can also be configured to function as a fan shroud. Fluid from the hydraulic unit as well as fluid from other sources can be circulated through the fluid cooler.

Abstract: A hydraulic control apparatus for a vehicular fluid-actuated power transmitting device provided with a lock-up clutch and an oil cooler, the lock-up clutch being operable between an engaged state and a released state according to a difference between pressures of a working fluid in an engaging fluid chamber and a releasing fluid chamber, the oil cooler being connected to a fluid passage communicating with the engaging and releasing fluid chambers, and operable to cool the working fluid, the hydraulic control apparatus including an oil cooler by-pass valve operable to permit the working fluid to by-pass the oil cooler, and a low-temperature by-pass device operable to open the oil cooler by-pass valve, for permitting the working fluid to by-passes the oil cooler, when a temperature of the working fluid is lower than a predetermined lower limit.

Abstract: A method of operating a hydraulic motor. In one embodiment, the method includes measuring a temperature of hydraulic fluid associated with the hydraulic motor and comparing the measured temperature of the hydraulic fluid to a first temperature threshold. The method also includes controlling an operational state of one or more hydraulic motor functions based at least partially on the comparison of the measured temperature of the hydraulic fluid and the first temperature threshold.

Abstract: A servo system includes pressurized fluid, and one or more fluid control devices (FCD) such as a valve or actuator, with at least one FCD having an element with a variable property that varies in response to a stimulus. The FCD controls a flow rate or pressure transmission of the fluid within the servo system. The element may include an active return spring having a variable stiffness. The servo system may operate as an interlock system for a transmission. A method for moving an output load using a servo system includes providing a first FCD with an active element, connecting an output load to a second FCD, activating the active element with a stimulus to vary a property of the active element, transmitting a force from the pressurized fluid to the second FCD, and moving the output load from a first position to a second position in response to the force.

Abstract: A compressed air supply device is provided for a utility vehicle, having a compressor which can be driven by a drive via a pneumatically switchable clutch, and a valve which can be activated by an electrical signal in order to optionally feed compressed air to a switching inlet of the clutch. The compressed air, which is fed to the switching inlet via the valve, is extracted from a compressed air preprocessing system via a non-return valve.

Abstract: An integrated system for: complete waste compactor operational control; remote fullness monitoring; and, remote performance and maintenance diagnostics. Such diagnostic information is transferred wirelessly or otherwise to one or more recipients, so as to directly provide a critical warning in real time. The waste compactor controller/monitor system allows for periodic real-time oil viscosity measurements of the hydraulic fluid to account for changes in such viscosity. The system adjusts the timing of the compactor stroke to permit more efficient operation and inhibit damage to the hydraulic ram and/or container during use.

Abstract: A hydraulic pressurizer system comprises a drive source, which drives a hybrid vehicle, a mechanical oil pump, which is driven by the drive source, an electrical motor, which is activated by a 12V battery, an electrical oil pump, which is driven by the electrical motor, and a control unit, which activates the electrical motor. The pressurizer further comprises a ratio-change mechanism, which is activated by hydraulic oil supplied by the mechanical oil pump and by the electrical oil pump to establish a speed change ratio, at which the rotational driving force of the drive source is transmitted to wheels with a rotational speed change. The control unit memorizes a characteristic value, which is specified from the temperature of the hydraulic oil and from the rotational speed of the electrical motor, and a threshold value for the rotational speed of the electrical motor, which threshold value corresponds to the characteristic value.

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: Systems and methods for collecting solar energy and converting it to heat, mechanical work, or electricity on a small scale and utilizing one or more system components originally adapted for use in a non-solar-power-generation application are described. Solar energy is used to heat a fluid that is part of a solar energy collector. This fluid transfers heat to the working fluid of thermodynamic engine, which converts some of the heat into mechanical work or electricity. One or more system parameters are monitored and controlled to enable improved efficiency under variable environmental conditions.

Abstract: A hydraulic drive system for storing and releasing hydraulic fluid includes a high pressure storage device, a low pressure storage device, and a pump-motor operating at a range of pump-motor speeds for converting between hydraulic energy and mechanical energy. The pump-motor is disposed between the high pressure device and the low pressure device. In normal operation, the hydraulic drive system enters a motoring mode where hydraulic energy is released from the high pressure storage device and converted to mechanical energy using the pump-motor. It also enters a pumping mode where mechanical energy is converted into hydraulic energy. A neutral state exists where hydraulic energy is neither stored nor released from the high pressure storage device. An approach for facilitating the application of a clutch when it is not a simple on/off mechanism provides an enhanced interface for the conversion between hydraulic energy and mechanical energy, thereby improving efficiency within the hydraulic drive system.

Abstract: A hydraulic energy conversion and dissipation system comprises a hydraulic retarder pump driven by a source of a mechanical energy needed to be dissipated for converting the mechanical energy into a waste hydraulic energy, a hydraulic flow retarder provided for converting the waste hydraulic energy into a thermal energy, at least one heat exchanger for dissipating the thermal energy generated by the hydraulic flow retarder and at least one cooling fan provided for producing a forced air flow through the heat exchanger. The cooling fan is driven by a corresponding hydraulic motor powered by the waste hydraulic energy of the pressurized hydraulic fluid flow generated by the hydraulic retarder pump for further dissipating the waste hydraulic energy. The system further includes a hydraulic fluid reservoir in fluid communication with an inlet of the hydraulic retarder pump.

Abstract: There is provided a working vehicle including: a hydraulic pump unit including a hydraulic pump main body operatively driven by a driving power source, and a pump case accommodating the hydraulic pump main body and having an inner space capable of storing oil; a hydraulic motor unit spaced apart from the hydraulic pump unit so as to operatively drive a corresponding driving wheel, the hydraulic motor unit including a hydraulic motor main body fluidly connected to the hydraulic pump main body so as to form an HST in cooperation with the hydraulic pump main body, and a motor case accommodating the hydraulic motor main body and having an inner space capable of storing oil; an auxiliary pump unit including an auxiliary pump main body operatively driven by the driving power source; a circulation line for fluidly connecting the auxiliary pump main body, the pump case and the motor case so that at least a part of oil, which has been discharged from the auxiliary pump main body, returns to a suction side of the auxil

Abstract: The invention relates to a method and system for controlling viscosity of a hydraulic fluid. The viscosity of a hydraulic fluid is usually very much dependent on temperature. By using existing throttles which generate a pressure drop, the hydraulic fluid can be heated by creating a power drain in these existing throttles through a controlled increase of the pressure through them. By controlled heating, the viscosity of a hydraulic fluid can be controlled. According to the invention, the existing throttles are preferably cavity-preventing openings in valves.

Abstract: Temperature of each cooling target fluid is detected. When the flow rate of a cooling target fluid passing through a cooling system is high, the fan revolution speed of a cooling fan of the cooling system is controlled to achieve a target fan revolution speed so that the detected temperature of the cooling target fluid reaches a preset target temperature. In cases where the engine is in a low idling state, the flow rate of each cooling target fluid passing through the cooling system is reduced. The fan revolution speed of the cooling fan is controlled to achieve a new target fan revolution speed that is lower than the target fan revolution speed.

Abstract: The invention is a fan revolution control method for controlling a pump-motor system, by controlling the fan revolution speed of a cooling fan adapted to be rotated by a fan motor to cool cooling target fluids. The pump-motor system drives the fan motor by a hydraulic fluid fed from a fan pump driven by an engine. The pump-motor system is controlled so the fan revolution speed starts from the minimum fan revolution speed when the engine is started up; the minimum fan revolution speed is maintained for at least several seconds; after the elapse of several seconds, the fan revolution speed is gradually increased from the minimum fan revolution speed. The fan revolution speed reaches a target fan revolution speed over a period of at least several seconds. The method prevents generation of peak pressure or pressure hunting.

Abstract: The device comprises a replenishing valve (24) having an opening control chamber suitable for being connected to a main duct (12, 14) of the circuit, and a closing control chamber, the pressure in said chambers making it possible to cause the moving member of the replenishing valve to move so as either to connect or not to connect the main duct to which said valve is connected to a pressure-free reservoir. The device further comprises a control valve (46) which is controlled as a function of at least one control parameter representing a state of the circuit other than pressure in said main duct to which said replenishing valve (24) is connected, in order to connect the closing control chamber to the pressure-free reservoir or in order to isolate said chamber from said reservoir.

Abstract: An apparatus for warm up control of an autonomous inverter-driven hydraulic unit has a warm up control section and a switch section. The warm up control section performs a predetermined process using a current speed and current pressure as input information and outputs a first switch command. The switch section is controlled by the first switch command so as to control on/off of power supplied to a fan motor. The apparatus causes an oil temperature to quickly rise to a level where a hydraulic unit driven by a hydraulic pump can work in an optimum condition.

Abstract: The load element state detecting portion 72 detects the completion of the filling of the hydraulic oil into the clutch 62 and the working limit of the accumulator 64 on the basis of the displacement of the spool valve element 42. That is, since the completion of the filling of the hydraulic oil into the clutch and the working limit of the accumulator 64 are directly detected, so that the completion of the filling of the hydraulic oil into the clutch 62 and the working limit of the accumulator 64 can be detected with high precision regardless of differences among products and the time-lapse variation. Furthermore, they can be detected without equipping any special device to the hydraulic control circuit, and thus there is an advantage that the device construction is simple.

Abstract: An electro-hydraulic system for operating a cooling fan and providing hydraulic fluid to a power steering system of the vehicle includes a hydraulic pump unit including first and second fixed displacement pumps and a common drive shaft for these pumps. A hydraulic fluid reservoir is connected to the inlet of each of the pumps. A priority valve is operatively connected to the outlet of the first pump and has an outlet connectible to the power steering system. This valve also has a second outlet connectible to a hydraulic motor for the cooling fan. This valve is arranged to provide a constant flow of hydraulic fluid to the power steering system. A hydraulic line connects an outlet of the second pump to the hydraulic motor. Hydraulic fluid flow through this line is combined with hydraulic fluid flow from the first pump to drive the motor.

Abstract: A method of flowing hydraulic fluid in a work machine is disclosed. The method includes generating a control signal from an input mechanism and generating a property signal indicative of a viscosity of the hydraulic fluid. The control signal and the property signal are received at a control module. The method also includes determining a desired volume flow rate for the control signal and determining a valve control signal required to achieve the desired volume flow rate for the control signal. The valve control signal is based upon the property signal. The valve control signal is output to a proportional valve to provide the desired volume flow rate through the valve for the command signal.

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: Pneumatic brake booster, in particular for a motor vehicle, comprising a reaction disk (30) interposed between a plunger (28) carried by a control rod actuated by the brake pedal and a thrust rod (32) acting on the primary piston of a tandem master cylinder, the reaction disk (30) being housed inside an annular metal part (36) which cooperates with a stop (50) of the thrust rod (32) by the intermediary of thermal expansion element (48) designed to compensate for the thermal expansion of the reaction disk (30) and its effect on a point of change of assistance ratio.