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: An engine lag down suppressing device of construction machinery, comprising a vehicle body controller (13) having a first torque control means and a second torque control means, and a third torque control means. The first torque control means controls a torque control valve (7) to the minimum pump torque (value: Min) according to a target engine rotational speed (Nr) when the operating device (5) in the non-operated state of an continues for a monitoring time (TX1) to suppress an engine lag down after a specified holing time to hold a torque to a low pump torque is passed when the operating device in the non-operated state is operated. The second torque control means controls the torque control valve (7) to hold the minimum pump torque for a specified holding time (Tx2) after the operating device (5) in the non-operated state is operated.

Abstract: The modular transmission uses only a pair of small and light hydraulic machines of remarkably improved volumetric efficiency with pistons having body portions substantially as long as the axial length of the respective cylinders in which they reciprocate. The two hydraulic machines operate in a closed loop, one being used as a pump driven by the vehicle's engine, and the other used as a motor. Each machine has a fully articulatable swash plate. By computer control, the angles of the swash plates of the two machines are infinitely varied to provide an appropriate optimum ratio of engine/wheel speed for all conditions from start-up, city driving, hill climbing varied according to load and steepness, and over-drive for highway. This complete vehicle operation is attained while the vehicle's engine continues to operate at relatively constant speeds and relatively low RPM.

Abstract: The present invention includes a hydraulic pump 10 driven by a prime mover 1, a traveling motor 12 driven with pressure oil delivered from the hydraulic pump 10, a control valve 11 for traveling that controls a flow rate of the pressure oil delivered from the hydraulic pump 10 to the traveling motor 12, a counterbalance valve 13 switched in response to a motor load pressure supplied via the control valve 11, that generates a braking pressure at a conduit L1A or L1B disposed on a return side of the traveling motor 12 as the load pressure becomes lower, an overspeed detection means 42 for detecting an overspeed state in the traveling motor 12, and a motor overspeed inhibiting means 50 for inhibiting rotation of the traveling motor 12 if the overspeed detection means 42 detects an overspeed state in the traveling motor 12 until a braking pressure is generated through a switchover at the counterbalance valve 13 and the traveling motor 12 is no longer in the overspeed state.

Abstract: A method is described for controlling a hydraulic system, particularly of mobile working machine, with at least one internal combustion engine driving at least one hydraulic pump with adjustable volumetric displacement and possibly additional fixed-displacement pumps.

Abstract: A modification torque ?T and a torque converter speed ratio e is computed from input and output revolution speeds of a torque converter 31. A first determination coefficient ? corresponding to the speed ratio e, and a second determination coefficient ? corresponding to a pump pressure are computed. A selector 87 selects the smaller one of these coefficients as a determination coefficient ?, and the modification torque ?T is multiplied by ? to provide a modification torque ?TA. An adder 89 adds the modification torque ?TA (negative value) to a pump base torque TR to provide a modified pump base torque TRA, whereby a maximum pump absorption torque TRA is controlled so as to become TRA. The maximum pump torque reducing control can then be performed while accurately confirming a work situation during the combined operation of travel and a working actuator.

Abstract: A zero turning radius mower has a dual hydrostatic pump with right and left pump arms. A linkage between the pump arms and a pair of control levers destrokes both sides of the pump simultaneously if engine speed drops below a specified value. The linkage allows each pump arm to have a first stroke range if the engine powering the pump is above the specified value, and a second smaller stroke range if the engine powering the pump is below the specified value.

Abstract: A control device for a work machine hydraulic pump used on a work vehicle according to the present invention has an object to rapidly accelerate the engine to start the vehicle quickly and to rapidly produce a large tractive force when an operator starts depressing the accelerator pedal while operating the work machine operating lever from the neutral position. The control device controls the capacity of the work machine hydraulic pump so as not to exceed the capacity upper limit corresponding to the currently detected engine speed, when the engine speed detected by the engine speed detecting device is equal to or lower than a predetermined speed (maximum torque speed).

Abstract: A fluid pump control device for wheel loaders includes an engine for driving an axle through a transmission, a main pump, a variable-displacement steering pump with a pump regulator, an auxiliary pump, an electronic proportional control valve provided on a discharge quantity control signal line leading to the pump regulator for variably controlling a pilot pressure conveyed the pump regulator, a hydraulic load detector for detecting a real hydraulic load (Px), an engine revolution detector for detecting the number of revolution (N1) of the engine, a transmission revolution detector for detecting the number of output shaft revolution (N2) of the transmission. A controller is adapted to control the electronic proportional control valve and hence the fluid discharge quantity of the steering pump, based on the real hydraulic load (Px), the number of revolution (N1) of the engine and the number of output shaft revolution (N2) of the transmission.

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: There is provided an oil supply unit for a running power transmission of a vehicle. The oil supply unit includes a housing, a hydraulic pump of a variable displacement type, a detecting mechanism and a control mechanism. The detecting mechanism is constructed to monitor a driven state of an engine. The control mechanism is constructed to operate an output adjusting member of the hydraulic pump to thereby regulate the discharge quantity against the suction quantity of the hydraulic pump based on the driven state of the engine.

Abstract: A hydraulic circuit for a tree-cutting machine having a feed mechanism powered by hydraulic fluid at the output of a hydraulic motor. The hydraulic motor may comprise a variable-displacement motor. The hydraulic circuit may comprise elements which provide an anti-stall mode, wherein the feed mechanism is operated to withdraw the cutting element upon pressure at an input port of the hydraulic motor exceeding a threshold.

Abstract: An electronic transmission control system that can achieve a transmission ratio based on the operator inputs and the current vehicle operating conditions. The transmission constantly connects the engine to the load, and the transmission ratio is only varied by a change in command from the present invention. The transmission's mechanical function is solely to vary the ratio between its input and output. In using the present invention, an operator must select an operating mode, either automatic or manual, using a two-position switch. While in the automatic mode, the present invention determines the vehicle speed by considering the position of the throttle and the operator's use of brakes. In the manual mode, the present invention further considers the operator's selection of a gear condition.

Abstract: To provide a control system, which can realize a saving in energy and an improvement in the efficiency of work, for a construction machine having an engine, hydraulic pumps, pump regulators, a fuel injection system, hydraulic actuators, control valves including plural flow control valves, and control devices, a controller is constructed including an engine speed control for correcting an inputted reference target engine speed NRO to obtain a corrected target engine speed NROO, a pump absorption torque control for determining a target maximum pump absorption torque value TRO, and a first correcting system for correcting the corrected target engine speed NROO and the target maximum pump absorption torque value TRO into a new target engine speed NRO1 and a new target maximum pump absorption torque TR1, respectively, in accordance with a coolant temperature signal TH1 detected by a coolant temperature detector.

Abstract: The present invention discloses a traveling control device, including a crawler type right and left traveling body; a right and a left hydraulic motor for operating the right and left traveling body said right and left hydraulic motors each having a pump as a hydraulic source; an operator means for outputting an operation command to the right and the left hydraulic motor; and a pump pressure controller means for controlling pump pressure to be supplied to the right and the left hydraulic motor according to a control input of the operator means, wherein the pump pressure controller means controls the pump pressure based on different pump pressure properties for single traveling in which only one of hydraulic motors is operated, and for double traveling in which both of hydraulic motors are simultaneously operated.

Abstract: A method is provided for controlling displacement of a variable displacement pump coupled to a load. The method includes determining an electrical signal to be applied to a proportional solenoid for a desired pump displacement based on known pump characteristics. The electrical signal is provided to the proportional solenoid. The displacement of the variable displacement pump is controlled based on the electrical signal to the proportional solenoid.

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: Disclosed herein is a hydraulic-pump controller that is capable of controlling absorbed pump torque in good balance against engine output at all times. In this hydraulic-pump controller, the discharge flow rates of the operating oil that are discharged from hydraulic pumps (9, 10) according to manipulation of manipulation units (12, 13) are predicted based on the discharge pressure of the hydraulic pumps (9, 10) that are driven by an engine (1), and based on the manipulation amount of the manipulation units (12, 13) that manipulate hydraulic actuators (27, 28), or a physical quantity correlating with the manipulation amount. Based on the predicted discharge flow rates and the discharge pressure, the absorbed torque of the hydraulic pumps is computed. Then, the predictive engine speed of the engine (11) is computed from the absorbed torque of the hydraulic pumps (9, 10) computed.

Abstract: In a construction machine according to the present invention wherein there is made an engine speed sensing control to control a pump horsepower in accordance with an engine speed of an engine, there is performed, in a low temperature condition with hydraulic oil temperature not reaching a preset temperature, a low temperature horsepower control involving setting the pump horsepower lower than at room temperature which is not lower than the preset temperature to lighten a burden on the engine. With this control, it is possible to prevent the occurrence of engine overtorque and hunting at a low temperature.

Abstract: A method is provided for controlling displacement of a variable displacement pump coupled to a load. The method includes determining an electrical signal to be applied to a proportional solenoid for a desired pump displacement based on known pump characteristics. The electrical signal is provided to the proportional solenoid. The displacement of the variable displacement pump is controlled based on the electrical signal to the proportional solenoid.

Abstract: An apparatus for controlling load on an engine is disclosed. The apparatus includes a continuously variable transmission driven by the engine. The apparatus further includes an engine speed sensor being adapted to sense the output speed of the engine and produce an engine speed signal indicative of the engine output speed and a travel speed sensor being adapted to sense the travel speed of the machine and produce a travel speed signal indicative of the machine travel speed. The apparatus yet further includes an electronic controller operable to compare the engine speed signal to an underspeed value and produce an integral error signal indicative of the difference between the engine speed signal and the underspeed value, supply an integral gain value based on the machine travel speed, modify the integral error signal through a proportional plus integral feedback controller to produce an underspeed request signal, and produce a command signal based on the underspeed request signal.

Abstract: A hydraulic circuit for a loader vehicle includes a working machine hydraulic circuit, a steering hydraulic circuit, a variable displacement auxiliary hydraulic pump, in which the displacement volume becomes smaller as the operating oil pressure becomes higher, when the operating oil pressure exceeds a predetermined oil pressure by receiving the operating oil pressure of the working machine hydraulic circuit, and a flow dividing valve for switching and supplying oil discharge from the auxiliary hydraulic pump to either one of the hydraulic circuits with a priority being given to the steering hydraulic circuit. A pump capacity control device includes a working machine hydraulic actuator, a working machine hydraulic pump, a steering pump, a steering pump capacity servo, a working machine load sensor, and an engine speed sensor.

Abstract: A control system for a liftcrane that utilizes a closed loop hydraulic system that utilizes feed back and feed forward control architecture to provide responsiveness normally associated with systems that do not require feedback.

Abstract: A fluid driven turbine for use in generating power by driving a load (32) with a fluid stream intercepting blades (12) of the turbine and the turbine applying power to the load during rotation of the blades in accordance with the invention includes a variable displacement hydraulic pump (19) which is driven by rotation of the blades, including a displacement control (57) having an element (62) which is responsive to a control signal for varying the displacement of the variable displacement hydraulic pump for producing a pressurized hydraulic fluid output to drive the load; and a hydraulic control valve (90) which generates the control signal in response to a hydraulic signal which is a function of speed changes of the blades and a pressure dropping orifice (114"), responsive to the hydraulic signal which is a function of speed changes of the blades which bleeds the hydraulic signal to a lower pressure, the orifice producing a coefficient of discharge of liquid independent of viscosity thereof; and wherein the

Abstract: A hydraulic drive system wherein differential pressures across flow control valves are controlled by pressure compensating valves to become the same value, i.e., a differential pressure .DELTA.PLS, and the differential pressure .DELTA.PLS is maintained at a target differential pressure .DELTA.PLSref by a pump displacement control system. For modifying the target differential pressure .DELTA.PLSref depending on change in rotational speed of an engine, a flow rate detecting valve is disposed intermediate between delivery lines of a fixed displacement hydraulic pump and a differential pressure .DELTA.Pp across a variable throttle of the flow rate detecting valve is introduced to a setting modifying unit to thereby modify the target differential pressure .DELTA.PLSref. The flow rate detecting valve changes an opening area of the variable throttle depending on the differential pressure .DELTA.Pp depending on the rotational speed of the engine.

Abstract: A hydrostatic/mechanical multiple path power transmission comprises an adjustable hydrostat unit (4), a summing planetary gearbox (10) with two input shafts (6, 8) and at least two output shafts, and a step gearbox (11) connected to the output shafts. In order to adjust low speeds and standstill precisely and rapidly, the following method is specified: rotational speed signals are formed by sensors (50, 51) on the two input shafts (6, 8) of the summing planetary gearbox (10), and are compared with each other by counters (61, 62); the actual pulse count difference formed in this way is compared with a desired pulse count difference, and a controller [sic] and the output signal of a controller (66) that responds to the result of this comparison effects adjustment of the hydrostat (4).

Abstract: A method for controlling the displacement of a variable displacement hydraulic pump to produce a desired flow of fluid is disclosed. The method includes the steps of: determining that the machine is being operated in a digging cycle; determining a desired displacement of the pump, the desired pump displacement being less than the maximum pump displacement; and controlling the pump displacement to the desired pump displacement to produce a desired flow of fluid.

Abstract: A fluid valve transmission having an automatic by-pass in neutral on the pump side and automatic brake or by-pass on the driven motor side while in the neutral position. Through holes and channels in the rotor are designed with close openings to open and close smoothly as the valve is turned, one opening as the other closes. All channels in the rotor are full of fluid at all times. The valve positions are designed with neutral midway between forward and reverse. This allows for quick start and stop and forward or reverse changes. Pressure equalization lines in the valve body from the pump and motor lines enter a circumferential channel on the rotor valve. This prevents the rotor from binding in high pressure applications.

Abstract: An apparatus to maintain optimum engine speed and cutter wheel speed to maintain peak power output of the engine and peak flywheel effect of the stump cutter wheel and method for maintaining optimum engine speed. The stump cutter has a rotating cutting wheel powered by an engine, and the cutter is mounted to be moved laterally. The mounting includes a boom and at least a first hydraulic cylinder for urging the boom to move along the path of travel over the surface of a stump. The hydraulic cylinder is activated by a hydraulic circuit which includes a source of pressurized hydraulic fluid. A pressure hydraulic line connects the source of hydraulic fluid to a first port of the hydraulic cylinder and a return line is connected to a second port of the hydraulic cylinder. A valve diverts a portion of flow from the pressure line to the return line or to a sump. The valve is shiftable between at least a first and a second position.

Abstract: A controller, for a variable capacity pump, prevents engine stalls due to rapid changes in operating load by increasing the pump absorption torque when the engine speed is high so as to increase the work amount and by reducing the pump absorption torque when the engine speed is low. The controller receives a signal from an engine speed sensor for detecting engine speed. A pump absorption torque curve is pre-set so as to be consecutively stepped with respect to engine speed so as to intersect at an engine rated point. The pump absorption torque is then calculated in accordance with increases or decreases in engine speed. The pump absorption torque is then set to prescribe values based on the results of these calculations and an instruction is outputted to a control valve in such a manner as to regulate a regulator of the variable capacity pump.

Abstract: In one aspect of the present invention, an apparatus for controlling the negative load of an engine is disclosed. The engine is drivingly connected to a hydro-mechanical drive system that includes a variable displacement pump and motor. An engine speed sensor senses the rotational speed of the engine and produces an actual engine speed signal indicative of the rotational engine speed. A travel speed sensor senses the travel speed of the machine and produces an actual travel speed signal indicative of the machine travel speed. An overspeed controller compares the actual engine speed signal to a proportional and integral threshold, produces a proportional and integral error signal indicative of the difference between the actual engine speed signal magnitude and the corresponding thresholds, calculates a proportional and integral control signal from the corresponding errors, combines the proportional and integral control signals and responsively produces a command signal.

Abstract: A hydraulic pump control system is shown that can control the absorbing torque of a hydraulic pump with respect to the engine power for driving the hydraulic pump in a well-balanced manner, and reduce a deviation of an actual revolution number from a target revolution number of the engine. A torque of hydraulic pumps during operation is estimated from a pump pressure and first and second line pressures. Based on the estimated torque, an output torque of the hydraulic pumps is controlled so that an error between a target revolution number and an actual revolution number of the engine becomes null.

Abstract: An air conditioning control system with a hermetic compressor for a motor vehicle is disclosed. The control system comprises a system for controlling the speed of the hermetic compressor (34) in such a way that the compressor driven by a variable-displacement pump assembly (30) coupled to a fixed-displacement hydraulic motor (33) rotates at a speed that is as close as possible to the rated compressor speed, and a sensor device (8) enables measurement of the rotation speed of the shaft of the hydraulic motor (33) connected to the compressor (34), so that a comparator (1) can change the forward direction of the plate (31) of the variable-displacement pump (30) depending on the changes in the speed of the hydraulic motor relative to a set speed.

Abstract: A device for matching the operation of a travelling unit in a construction vehicle is disclosed. The device reduces the required levering force of a travelling control pedal, easily controls the rotating force of an engine, and safely changes the engine output torque in accordance with both the levering stroke of the travelling control pedal and a travelling resistance. The device has a pressure reduction valve which is synchronized with a levering motion of a travelling control pedal in order to feed pilot fluid from a pilot pump to a direction select valve. A branch line is branched from a fluid line extending between the pressure reduction valve and the direction select valve. A hydraulic cylinder is connected to the branch line and selectively receives the pilot fluid through the branch line when the travelling control pedal is levered.

Abstract: A hydraulic drive assembly includes a variable displacement pump fluidly connected in a closed loop circuit with a motor for driving an ancillary device, such as a fan. An auxiliary pump can be operatively connected to the pump, the motor and a reservoir for replenishing fluid losses in the closed loop circuit. An auxiliary circuit connected to the pump has a recirculating passage fluidly connected to the closed loop circuit downstream of the motor to reduce the necessary reservoir volume. A method for smoothly and continuously adjusting the output of the pump to drive the ancillary device is also disclosed.

Abstract: A control system for an aircraft's electrically driven hydraulic pump. An electronic motor controller having closed loop feedback is utilized to directly control the prime mover speed in response to pump loading.

Abstract: The present invention relates to a method of controlling a speed change of a hydraulic driving apparatus for a vehicle and to a speed changing device which provide excellent traveling efficiency and controllability. To this end, the method of controlling a speed change comprises discriminating between at least a powering travel and a braking travel from an accelerating amount (.theta.) and rotational speed of a hydraulic motor (50) for controlling. At the time of the powering travel, a directional control valve (21) can be fully opened in response to the rotational speed (.omega.out) of the hydraulic motor (50) and the accelerating amount (.theta.). In addition, the speed changing device comprises an accelerating amount detection sensor (61a), a motor rotational speed sensor (52) for detecting a vehicle speed (V), and a control device (60) for discriminating, from the accelerating amount (.theta.) and the vehicle speed (V), between the powering travel and the braking travel for providing a control.

Abstract: An overspeed control for a hydrostatic transmission of a mobile machine includes a speed control valve arrangement connected to a fixed displacement pump through a supply line and to a pressure responsive displacement controller of a variable displacement hydraulic pump of the transmission. An overspeed control valve is connected to the supply line and is operative for reducing the fluid pressure level in the displacement controller when the speed control valve arrangement is in an operative position and the rotational speed of the engine exceeds a predetermined level. This reduces the displacement of the variable displacement pump (which acts as a motor in a downhill situation) and thus increasing engine retarding and transmission losses for preventing the positive grade from accelerating the machine, engine and/or the components of the hydrostatic transmission to speeds exceeding their designed limits.

Abstract: Each attachment for a hydraulically actuated device includes a digitally coded connector which informs a control device about its identity. The control device includes a library which relates the digitally coded identity with fluid parameters of pressure and flow rate required for operation of the hydraulically operated device. The control device outputs signals which control the accelerator of an engine, and also controls pump operations to establish the fluid parameters appropriate for the hydraulically actuated device. When a second device is actuated simultaneously with the original device, the control device automatically compensates with adjusted fluid parameters to permit optimum operation of both devices at the same time.

Abstract: A control system designed such that if a heavy load is imposed on a vehicle during running and a hydraulic relief state in which an oil pressure in a hydraulic circuit for a hydrostatic transmission unit exceeds a relief pressure is detected, the angle of a discharge controlling swash plate for a pump is reduced to a specified value (e.g., 50% of the maximum angle) or less, whereby the stall of the vehicle and the overheat of machine parts are prevented.

Abstract: This invention aims to improve the operability in a hydraulic drive machine. According to a load Pp on work machine actuators 3 and 4, a differential pressure of a discharge pressure Pp of a hydraulic pump and a load pressure PLS is varied. Further, the differential pressure is varied so that the differential pressure between the discharge pressure Pp of the hydraulic pump 2 and the load pressure PLS decreases as the load Pp on the work machine actuators 3 and 4 increases and a rotational speed .epsilon.E of an engine decreases. Furthermore, the rotational speed .epsilon.E of the engine 1, discharge pressure Pp of the hydraulic pump 2, the operation amounts S1 and S2 of the various operation levers are detected, respectively, the absorbing torque of the hydraulic pump 2 is set based on the detected rotational speed .epsilon.E and a target rotational speed .epsilon.

Abstract: A method for putting into operation a vehicle with an electronically controlled automotive hydrostatic transmission, wherein an output current of an electronic control by means of at least one proportional pressure-reducing valve is used for generating a control pressure acting upon the servo system of the variable displacement pump. The method is performed by the following steps: a) determining a limit value of a driving regime of the vehicle; b) detecting, digitizing and reading-in at least one current operational parameter of the transmission into the electronic control; c) determining and detecting at least one characteristic value of the output current of the electronic control corresponding to the value of the driving regime of the transmission to the one proportional pressure-reducing valve, and d) calculating a current characteristic on the basis of the value of the output current for achieving reproducible driving properties.

Abstract: A circuit arrangement for controlling the output torque of a hydrostatic machine connected to a hydraulic system having an impressed operating pressure. The circuit arrangement has a control element for changing the output torque of the machine based upon operating parameters corresponding to pressure, speed, temperature and the like. Control means are supplied with a desired torque value for generating a control signal for actuating the control element. Pick-up means are connected to the control means and to the control element for picking up a pivotal angle .alpha. or an eccentricity E, respectively, representing an actual displacement volume of the hydrostatic machine. The pivotal angle .alpha. and the eccentricity E are measured in either an analog or a digital manner. When measured in an analog manner, the desired value of the pivotal angle is .alpha.=M/P and the desired value of the eccentricity is E=M/P, where M is the torque and P is the pressure.

Abstract: An apparatus for controlling the load of an engine associated with an hydrostatic drive system is disclosed. The apparatus modifies a pump displacement command signal in response to the actual and desired engine acceleration. The modified pump displacement command signal is used to control the displacement of a variable pump in order to regulate the load on the engine to achieve optimum efficiency.

Abstract: A hydromechanical transmission shifting control system and method includes a hydromechanical transmission and a number of clutches connected to the transmission. A microcontroller receives various signals generated by the operator, engine, transmission, and the load. The microcontroller controls the ratio of the input to output speed of the transmission as well as the engagement or disengagement of the number of clutches based upon the various input signals.

Abstract: An apparatus for and a method of controlling the engine and pumps of hydraulic construction equipment capable of achieving automation of the hydraulic construction equipment by controlling the oil quantity fed to solenoid controlled proportional valves such that it is proportional to the manipulation amount of a manipulation command unit through a computation performed by a controller on the basis of engine RPM data from an engine RPM detection unit and pump delivery pressure variation data from a pump delivery pressure detection units so that the suction horse power of each of the pumps corresponds to the maximum output horse power of the engine and by controlling the oil quantity fed to the hydraulic cylinders 105a and 105b by oil quantity control valves such that it corresponds to the manipulation amount and manipulation ratio from the manipulation command unit.

Abstract: The maximum value of target motor speed ratio is calculated from the allowable revolution speed of a motor, and based on the maximum value, an allowable value of target speed ratio is set. Target speed ratio is then limited to the allowable value or less. This enables it to prevent overrun occurring e.g., when the vehicle rolls down a hill.

Abstract: An apparatus for controlling an injection molding machine includes a slipping detection device to detect the slippage of a pump motor which drives a hydraulic pump; a rotational velocity sensor which detects the rotational velocity of the pump motor, for example; and an instruction signal correcting circuit having an addition circuit which adds the operation circuit which obtains from the detected signal of the rotational sensor a flow rate instruction correcting signal to compensate the reduction of the discharge flow rate due to the increased slippage, and the flow rate instruction correcting signal to the flow rate signal, and then, detects the slippage of the pump motor and corrects the magnitude of the flow rate instruction signal thereby to compensate the discharge flow rate.

Abstract: A control device for an actuator adapted to control a discharge pressure of a variable discharge pump by means of a regulator and capable of ensuring sufficient flow control range of change-over valves with respect to a spool stroke even when the number of rotations of an engine for driving the variable discharge pump is reduced to decrease a discharge rate of fluid from the variable discharge pump. Elastic force of a spring of a valve constituting the regulator is adjusted by means of a cylinder associated with a throttle lever for controlling the engine. Also, a control valve is arranged so as to be associated with the throttle lever, so that a pressure on a downstream side of the variable discharge pump is increased to change over the valve.

Abstract: A hydraulic nonstep transmission apparatus with low costs and high reliability is provided which is capable of automatically determining a speed-change ratio corresponding to engine speed and motor load and capable of smoothly performing clutch operation to a clutch-on state through a clutch meeting state. The apparatus comprises: a clutch means provided in a hydraulic closed circuit; a governor hydraulic actuator for moving the motor swash plate toward its vertical position in accordance with an increase in the rotational speed of an engine; and a governor hydraulic pressure switch means provided in a governor hydraulic fluid passage of the governor hydraulic actuator and drivingly connected to the clutch means to disconnect the governor hydraulic pressure during the period from a clutch-off state to the elapse of the clutch meeting state and to supply the governor hydraulic pressure before and after the transition to clutch-on after substantially completing the clutch meeting state.