Abstract: The invention relates to a self-propelled construction machine, in particular a road milling machine, stabiliser, recycler or surface miner, which has a machine frame 2 supported by at least three running gears 10A, 10B, 11A, 11B, a drive device 14 for driving at least two running gears, and a work roller 4 arranged on the machine frame. The invention also relates to a method for controlling a construction machine of this kind. The drive device 14 comprises adjustable hydraulic motors 15, 16, 17, 18 associated with the drivable running gears, which hydraulic motors have a displacement volume Vg that can be varied by an adjusting device 15A, 16A, 17A, 18A, and comprises at least one adjustable travel drive-hydraulic pump 19 driven by at least one drive motor to supply the hydraulic motors with a variable total volume flow Q of hydraulic fluid.

Abstract: The invention relates to a hydraulic assistance device comprising: a hydraulic machine (30) capable of driving a wheel (W) of the craft; a variable displacement pump (10) comprising a double-acting actuator (12) defining two control chambers (12 a, 12 b) for hydraulically controlling the capacity of said pump (10); two supply lines (40a, 40 b) that connect the hydraulic machine (30) and the variable displacement pump (30) in order to form a closed circuit, characterised in that the device further comprises: two control lines (80a, 80 b), each being respectively drawn from one of the two supply lines (40a, 40 b) and being configured to respectively supply one of the two control chambers (12a, 12 b); two electrically calibratable pressure limiters (90a, 90 b) respectively disposed on the two control lines (80a, 80 b).

Abstract: An axial piston motor having a cylinder housing, in which a plurality of cylinders are formed, and having pistons which are movably guided in the cylinders, wherein the pistons are attached to a swash plate and wherein a flow of a fluid that has entered via an inlet into the axial piston motor is controlled into and out of the cylinders by means of inlet and outlet valves, wherein the inlet and/or outlet valves comprise fluid change openings which are formed in a cylinder head plate and which can be temporarily released and covered by means of a rotary slide, for which purpose the rotary slide forms at least one passage opening.

Abstract: The aim of the invention of for the hydrostatic drive to enable a lowering of the feed pressure provided by the feed pump and, at the same time, to effect a supply of the adjustment unit of the drive that is proper with respect to the pressure and the delivery rate. This aim is achieved in that the adjustment unit (5) of the drive is supplied with hydraulic energy by an electrohydraulic supply unit (6), wherein the supply unit (6) consists of an electric motor (7) and an auxiliary pump (8) coupled thereto and wherein the outlet of the auxiliary pump (8) is connected to the adjustment unit (5) directly or by means of a check valve (18). Hydrostatic drives according to the invention are used, for example, in self-propelled working machines.

Abstract: A turbocharger can include a center housing; a compressor assembly operatively coupled to the center housing; and a turbine assembly operatively coupled to the center housing, where the center housing includes a bearing boss that includes a bore wall with opposing axial ends that define an axial through bore having opposing axial openings, an oil inlet, an oil outlet, an arcuate oil passage in fluid communication with the oil inlet, an oil passage in fluid communication with the arcuate oil passage and an opening in the bore wall, and an oil drainage passage in fluid communication with the opposing axial openings of the through bore and in fluid communication with the oil outlet.

Abstract: A hydraulic unit includes a driving mechanism whose displacement volume is adjustable to two operational states by means of a position-able adjustment element. The adjustment element can be positioned by a servo piston of a servo unit into a first, initial position and a second, operative position. A first front face and a second front face of the servo piston, which are opposing each other, can be pressurized individually with pressurized hydraulic fluid in order to position the servo piston at either end position of a servo cylinder of the servo unit. The servo piston is of a stepped design thereby forming a ring-shaped damping surface opposing the first front face. In the servo cylinder a ring-shaped shoulder surface is formed opposing the damping surface such that a damping volume is formed in the servo cylinder by the damping surface, the shoulder surface and the servo cylinder.

Abstract: A bi-directional pump connected to a motor by a pair of supply/discharge lines; a regulator changes the bi-directional pump tilting angle; and a controller controls the regulator based on a turning signal outputted from a turning operation valve. At the turning acceleration, at which the signal increases, the controller calculates a motor flow rate passing through the motor and an instruction flow rate determined based on the turning signal. If the instruction flow rate is greater than a reference flow rate obtained by adding a predetermined value to the motor flow rate, the controller controls the regulator so the bi-directional pump tilting angle is adjusted to a tilting angle realizing the reference flow rate. If the instruction flow rate is not greater than the reference flow rate, the controller controls the regulator so the bi-directional pump tilting angle is adjusted to a tilting angle realizing the instruction flow rate.

Abstract: A hydrostatic traction drive in a closed hydraulic circuit includes two hydraulic machines in the closed hydraulic circuit and a control unit configured to control a braking torque of the traction drive. A method for controlling the hydrostatic traction drive includes controlling the braking torque for the hydrostatic traction drive.

Abstract: The invention concerns a hydrostatic drive with a closed hydraulic fluid circuit comprising a hydraulic motor and a variable displacement pump. A feed pump feeds hydraulic fluid under pressure. A control device regulates pressure to a double-sided servo control unit comprising a control piston in a double-sided control cylinder so that the control piston can open a feed line for hydraulic fluid to one side while opening a discharge line on the other. The control device comprises an actuator at the cylinder by means of which force can be exerted onto the piston. A preload element exerts force onto the piston. The pressure generated by the variable displacement pump returns via a return line such that force is exerted in the direction of the piston, if inactive, the piston is maintained by the preload element and the pressure of the variable displacement pump.

Abstract: A drive controller for a motor of a compressor includes a drive circuit that applies voltages to windings of the motor. A speed control module controls the drive circuit to rotate the motor at a requested speed. A speed determination module generates the requested speed based on a speed demand from a system controller. A lost rotor control module identifies a lost rotor condition and, in response to identifying the lost rotor condition, instructs the speed determination module to set the requested speed to an override speed that is lower than the speed demand. The lost rotor control module identifies the lost rotor condition in response to a comparison of a speed error with an adaptive threshold. The speed error is based on a difference between requested and estimated speeds of the motor. During first and second system states, the adaptive threshold is set to first and second thresholds, respectively.

Abstract: A hydrostatic drive system for a machine is provided. The hydrostatic drive system includes a first hydraulic circuit, and a second hydraulic circuit. The first hydraulic circuit includes a first pump and a first hydraulic motor configured to selectively receive a flow of pressurized hydraulic fluid from the first pump at a first pressure. The second hydraulic circuit includes a second pump and a second hydraulic motor configured to selectively receive the flow of the pressurized hydraulic fluid from the second pump at a second pressure. The hydrostatic drive system further includes a controller configured to maintain a pressure balance between the first and the second hydraulic circuits based on a difference between the first pressure and the second pressure.

Abstract: A hydraulic control system is disclosed. The hydraulic control system may have an input device to generate a first signal indicative of a desired swing motor movement, and a control valve configured to selectively pass fluid to the swing motor and drain from the swing motor to drive the swing motor based on the first signal. The hydraulic control system may also have a pressure sensor to generate a second signal indicative of a swing motor pressure, a speed sensor configured to a third signal indicative of a swing motor speed, and a controller configured to make a comparison of at least one of the swing motor speed and the swing motor pressure with a threshold speed and a threshold pressure, and open the control valve to drain fluid from the swing motor to the tank based on the comparison when the input device is in a neutral condition.

Abstract: The invention addresses the problem of avoiding insufficient flow being supplied to the hydraulic actuator and speed becoming insufficient during light loads in hydraulic machinery such as hydraulic shovels when the engine rotation speed is set low during normal work. The solution is to increase the discharge flow of the hydraulic pump (2) by increasing the rotation speed of the engine (1) above the target rotation speed set by the engine rotation speed-setting means (14) when the hydraulic pump (2) discharge pressure is at the light load pump discharge pressure, the hydraulic pump (2) inclination angle is at the maximum inclination angle, and the negative control signal pressure is at the signal pressure when the hydraulic actuator-operating means (7) is at full operation.

Abstract: A slewing-type working machine capable of reducing back pressure generated during slewing. The slewing-type working machine includes: a base carrier; an upper slewing body; a hydraulic motor including first and second ports and slewing the upper slewing body; a hydraulic pump, a slewing operation device including an operating member; a control valve controlling the hydraulic motor based on the operation signal of the slewing operation device; first and second pipe-lines connecting the first and second ports of the hydraulic motor to the control valve; a communication switching device capable of switching communication and cutting of between both pipe-lines and the tank; and a switching command section operating the communication switching devices, when the upper slewing body is slewed, to bring only a pipe-line, which corresponds to a discharge-side pipe-line of the hydraulic motor, of the pipe-lines into communication with the tank, while bypassing the control valve.

Abstract: In a work vehicle, a control section increases the displacement of a hydraulic motor for travel when the drive circuit pressure becomes larger than a target pressure determined according to the engine rotational speed, and reduces the displacement of the hydraulic motor when the drive circuit pressure becomes smaller than the target pressure. The control section increases the target pressure of the hydraulic motor for travel when changing the matching point of the absorption torque curve of the hydraulic pump with respect to the output torque curve of the engine.

Abstract: A method for ascertaining a rotational speed parameter for determining a setpoint torque for driving a drivetrain. The drivetrain comprises a first and at least one second drive assembly for driving a hybrid vehicle. The first drive assembly can be coupled to the drivetrain by means of a clutch. The second drive assembly is mechanically coupled to the drivetrain. When the hybrid vehicle is being driven by means of at least the first drive assembly, the rotational speed parameter corresponds to the value of a shaft rotational speed. When the hybrid vehicle is being driven only by means of the second drive assembly, the rotational speed parameter corresponds to the value of a determined rotational speed.

Abstract: A hydraulic system adapted to recover inertial energy is disclosed. The hydraulic system includes a pump, a variable displacement pump/motor having an input/output shaft, an accumulator, and a valve arrangement. The valve arrangement is operable in: a) a first mode where the variable displacement pump/motor is driven by the pump to rotate the input/output shaft and the load; b) a second mode where the variable displacement pump/motor uses inertial energy from a deceleration of the load to charge the accumulator; and c) a third mode where the variable displacement pump/motor is driven by the accumulator to rotate the input/output shaft and the load. The hydraulic system also includes a controller for controlling operation of the pump, the variable displacement pump/motor and the valve arrangement.

Abstract: The described system and method allow a controller to calibrate a transmission variator of a continuously variable transmission for torque control by obtaining static and dynamic qualities and parameters of the variator through an automated calibration procedure. The system and method employ a pair of transmission mode configurations and operational configurations in combination to obtain system-specific information. In this way, the system is able to calibrate out the system variations to provide effective feed forward torque control of the continuously variable transmission. In an embodiment, a first calibration operation is performed while the transmission is neutralized and a second calibration operation is performed while the transmission is engaged in a mode providing a fixed variator output speed.

Abstract: A working vehicle with an HST in which over-rotation of a hydraulic pump in the HST or the pump input shaft thereof is prevented when a main clutch is disconnected during a run. When a main clutch connection/disconnection detection means detects the disconnection state of the main clutch during a run, a control means judges whether a vehicle speed detected by a vehicle speed detection means is at least a set speed or not, and if the vehicle speed is at least the set speed, the movable swash plate of the hydraulic pump in an HST is controlled to sustain it at the current inclination angle.

Abstract: To perform updating of maximum values and minimum values of measurement data with a simple procedure without incurring an increase in the computational load of an arithmetic processing element such as a microcomputer. When processing is started, a most recent maximum value stored in a nonvolatile storage element is written to a maximum value-use variable Xmax and a positive maximum value is written to a minimum value-use variable Xmin. Each time temperature data is acquired, a value of acquired data Xk and a most recent minimum value Xmin are compared and the smaller value is set as a new minimum value Xmin. Each time updating of this minimum value is repeated a predetermined number of times of processing Ns, the minimum value Xmin at that point in time and the maximum value Xmax are compared and the larger value is set as a new maximum value Xmax.

Abstract: A hydrostatic fan drive for internal combustion engines is disclosed, having a primary unit that can be driven by the internal combustion engine, and having a fan motor by means of which a blower fan can be driven. A hydraulic reservoir is disposed at a high-pressure line connecting the primary unit to the fan motor. A hybrid fan drive for internal combustion engines is thus provided, allowing fan operation even if the internal combustion engine is switched off. An increased maximal available power of the internal combustion engine is available in transition, despite the fan operation, because the fan motor can be supplied with pressurized media by the hydraulic reservoir in such cases (in transition).

Abstract: The present invention includes: a hydraulic pump 10 that is driven by a driving motor; a travel motion motor 12 that is driven with pressure oil supplied from the hydraulic pump 10; a travel motion control valve 11 that controls a flow rate of the pressure oil supplied from the hydraulic pump 10 to the travel motion motor 12; a means for operation 22a with which the travel motion control valve 11 is operated; a means for rotation rate detection 95 that detects a rotation rate N of the travel motion motor 12; and a means for motor over rotation prevention 14, 17, 32 that reduces the rotation rate of the travel motion motor 12 if the means for rotation rate detection 95 detects a rotation rate equal to or higher than a predetermined rotation rate upper limit Nmax.

Abstract: A drivetrain system for use in a mobile machine is disclosed. The drivetrain system may have a first rotary fluid actuator, a second rotary fluid actuator, an input device, and a controller in communication with the first rotary fluid actuator, the second rotary fluid actuator, and the input device. The controller may be configured to determine a desired change in an effective gear ratio of the drivetrain system, and determine a total displacement change associated with the first and second rotary fluid actuators that produces the desired change in the effective gear ratio. The controller may also be configured to compare the total displacement change to a threshold change level, affect simultaneous displacement changes in the first and second rotary fluid actuators when the total displacement change exceeds the threshold change level, and affect sequential displacement changes in the first and second rotary fluid actuators when the total displacement change is less than the threshold change level.

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

Abstract: 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 drive system of a working vehicle including a main engine drivingly connected to a hydraulic pump. The hydraulic pump is connected to first and second hydraulic motors. When an undesirable operating condition is detected, a control device shifts an actuator associated with at least one of the wheels, to reduce the displacement volume of the hydraulic motors driving that wheel. In addition, shifts are made in the actuator of the respective other hydraulic motor and/or in the actuator of the hydraulic pump, in order to maintain a constant speed of travel. The control device shifts the actuator of the hydraulic motor of the other wheel toward greater displacement, and if that shift is insufficient to compensate for the undesirable operating condition, the control device will shift the actuator of the hydraulic pump in the direction of reduced displacement volume.

Abstract: The apparatus is an automatic velocity control system for an agricultural machine. Three feedback circuits are used to increase reliability and repeatability of the apparatus despite variations in load and ground conditions and non-linear responses of control components. A solenoid current sensor supplies a feedback signal to control a current controller for solenoids controlling a hydraulic valve, a hydraulic cylinder position sensor provides a feedback signal to counteract the non-linearity of the hydraulic valve controlling the hydraulic cylinder, and wheel speed sensors supply vehicle speed signals to be compared to the signal from the operator's speed control. A microprocessor processes the sensor signals to maintain the desired velocity.

Abstract: A method and apparatus for controlling the motor output speed of a variable displacement hydraulic motor are disclosed. The method may include determining a value indicative of a motor output speed, determining a value indicative of a desired motor output speed, determining a desired position of a control valve using a nonlinear feedback control law, and, controlling the motor output speed as a function of the control valve position, wherein the nonlinear feedback control creates a first order system response.

Abstract: A method and apparatus for controlling the motor output speed of a variable displacement hydraulic motor are disclosed. The method may include determining a value indicative of a motor output speed, determining a value indicative of a desired motor output speed, determining a desired position of a control valve using a nonlinear feedback control law, and controlling the motor output speed as a function of the control valve position, wherein the nonlinear feedback control creates a first order system response.

Abstract: A vehicle, such as a loader, has an operator-controlled hydrostatic drive that includes hydrostatic motors to drive wheels. The speed of the motors is proportional to an operator input provided to a controller that regulates the flow of hydraulic fluid from a pressure source to the motors. The regulation of fluid under pressure to the motors is achieved by utilizing electrical displacement control pumps that provide fluid flow in proportion to an input signal. The motors are fixed displacement motors, and when the wheels overrun as the vehicle rolls down an incline, the motors will act as pumps. The movement of the wheels is sensed to provide a signal to the controller to adjust one or both of the control pumps to provide a balancing counter pressure at the work port of the motor to insure that the vehicle will not creep or roll when it should be stopped.

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

Abstract: Differential pressures across flow control valves 6a, 6b and 6c are controlled by pressure compensating valves 7a, 7b and 7c to be held at the same value, i.e., a differential pressure &Dgr;PLS, and the differential pressure &Dgr;PLS is maintained at a target differential pressure &Dgr;PLSref by a pump displacement control unit 5. For changing the target differential pressure depending on change in revolution speed of an engine 1, a flow detecting valve 31 is disposed in a delivery line 30a, 30b of a fixed displacement hydraulic pump 30, and a differential pressure &Dgr;Pp across a variable throttle portion 31a of the flow detecting valve 31 is introduced to a setting controller 32. A selector valve 50 operable to shift between a fully closed position and a throttle position is disposed in parallel to the flow detecting valve 31 and is shifted by a control lever 51.

Abstract: A control system sets a set maximum speed of a utility vehicle, below the capable maximum speed of the vehicle, and recalibrates speed output signals corresponding to the set maximum speed. The system includes a microcontroller and a user-operated vehicle speed actuator, signal-connected to the microcontroller. The speed actuator is calibrated to actuate speeds, via the microcontroller, in a range from a minimum speed to a maximum speed. A user-operated speed set activator is used in conjunction with a ground speed sensor to set the set maximum speed. The microcontroller records the new maximum speed of the vehicle, and recalibrates the pedal position according to the new maximum speed.

Abstract: A self-propelled vehicle, such as a loader, has a hydrostatic drive that includes hydrostatic motors to drive ground engaging wheels under control of the operator. The rotational speed of the motors is proportional to an operator control input provided to a controller which in turn regulates the flow of hydraulic fluid under pressure from a pressure source to the motors. In the form shown, the regulation of the hydraulic fluid under pressure to the motors is achieved by utilizing electrical displacement control pumps that will provide a flow of fluid to a connected motor in direct proportion to an input signal as the flow source. The motors are fixed displacement motors, and when the wheels tend to overrun as the vehicle rolls down a hill or incline, the motors will act as pumps.

Abstract: A hydrostatic continuously variable transmission includes a fixed capacity hydraulic pump and a variable capacity hydraulic motor, connected by a hydraulic closed circuit. A control system and method for the variable transmission provides a good deceleration feeling when going downhill. In accordance with the control system and method, a range of a selected gear is determined. Next, it is determined whether the vehicle is in an automatic gear shift mode. If these conditions are met, it is then determined whether or not certain criteria for descent control are satisfied. The certain criteria may include: (1) whether the throttle is closed; (2) a speed or acceleration of the vehicle; (3) whether the acceleration exceeds a threshold; and (4) whether simultaneous satisfaction of conditions (1)-(3) exist for a period of time exceeding a fixed time. If all of the criteria are satisfied, the gear ratio is shifted by a specified amount towards a LOW side.

Abstract: The present invention provides a vehicle traveling control apparatus for a vehicle with an HST and a mechanical transmission, which are connected in tandem to each other and interposed in a traveling power transmission path between a driving power source and driving wheels. The vehicle traveling control apparatus includes a speed-change control mechanism which in turn includes a signal detection part and a control part for controlling the changing of the output speed of the HST and the shifting operation of the mechanical transmission. The signal detection part includes a load-torque detection means. The control part is designed to control the mechanical transmission and the HST based upon the detected results by the load torque detection means so that where the vehicle lies in a high load torque state, the control part downshifts the mechanical transmission to a lower speed stage, while increasing the output speed of the HST.

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: An overtop position is to be established in a hydrostatic type continuously variable transmission, and an increase of the maximum speed and the maintenance of power performance are to be made compatible with each other. In a hydrostatic type continuously variable transmission, the angle of inclination of a movable swash plate is controlled in such a manner that a target Ne is calculated from both RC (riding condition) and throttle valve opening, then the target Ne thus calculated is compared with an actual Ne to determine a rotational direction and DUTY of a control motor. The operation of the control motor is controlled in accordance with the thus-determined data and angle information on the angle of the movable swash plate provided from an angle sensor.

Abstract: An apparatus, for controlling a plurality of hydraulic motors and a clutch for driving a drive shaft, can prevent a speed change shock and a load slip of a hydraulic motor as well as making a structure simple. The apparatus includes: a first volume variable hydraulic motor (1), connected to the drive shaft (3) through the clutch (5); a second volume variable hydraulic motor (2), which is always connected to the drive shaft (3); first tilt rotation control means (7, 8), for controlling a tilt rotation amount (a discharge volume cc/rev) of the first hydraulic motor by receiving a drive side pressurized oil (Pac) of the first hydraulic motor; and a zero tilt rotation holding means (10, 10A), for holding the tilt rotation amount of the first hydraulic motor at substantially zero in a state wherein the tilt rotation amount of the first hydraulic motor is controlled to be substantially zero.

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 control system for a hydraulic circuit having a tank, a pump, a supply conduit connected to the pump, a reversible hydraulic motor, an input conduit connected to the motor and an output conduit connected to the motor is disclosed which comprises a first, second, third, and fourth independently operable electrohydraulic metering valve, the second and third valves being disposed between the supply conduit, the first and second valves being disposed between the input conduit, and the third and fourth valves being disposed between the output conduit, a first pressure sensor connected to the supply conduit for sensing a pressure within the supply conduit, a second pressure sensor connected to the input conduit for sensing a pressure within the input conduit, a third pressure sensor connected to the output conduit for sensing a pressure within the output conduit, a speed and directional sensor connected to the motor for sensing the speed and direction of the motor, and a controller connected to the pump, the valv

Abstract: A slide driving device employs a variable-displacement pump/motor for driving a rotating element of the slide driving device. The displacement volume of the variable-displacement pump/motor, whose output drives the slide, is varied in response to deviation of measured driver parameters from commanded driver parameters. An energy storage device temporarily absorbs excess energy during a portion of a molding cycle, and returns the energy to the system for re-use. In one embodiment, the energy storage device is an accumulator. In a second embodiment, the energy storage device is a flywheel. The combination of variable displacement volume and energy storage maintains the fluid pressure substantially constant during a cycle of the slide driving device.

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: 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 actuator package of the present invention comprises a variable displacement hydraulic motor for driving an inertia object with acceleration or deceleration, a speed sensor for detecting a speed of an output shaft of the hydraulic motor, a control valve for continuously varying the capacity of the hydraulic motor, which are integrally provided inside or outside a casing of the hydraulic motor, and an assembling body formed by integrally assembling an accumulator serving as a hydraulic source of the hydraulic motor and an airtight tank into a common pedestal, said assembling body being mounted on said casing, first and second ports of the hydraulic motor communicating with the accumulator and the airtight tank in the casing and the pedestal, and first and second external connection ports being defined in the pedestal or the casing, and capable of being connected to the first and second ports from the outside.

Abstract: A speed sensor for sensing the speed and direction of a hydrostatic motor or pump measures the speed, monitors an operator input, processes this information and generates a high power output to drive a solenoid valve or electrical displacement control. The sensor is housed in a single package mounted directly on the hydrostatic motor or pump. The function of the sensor can be easily modified with software changes.

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: A response control system for a hydrostatic-mechanical transmission. In this system, it is determined in digging/moving operation whether an actual speed ratio which is the ratio of the revolution speed of the output shaft to the revolution speed of the power source is equal to a specified value or less, and if so, a target speed ratio which is a target value for the ratio of the revolution speed of the output shaft to the revolution speed of the power source is set, limiting the amount of change in the target speed ratio per unit time. Based on the target speed ratio thus set, the angle of at least either of discharge controlling swash plates is controlled, thereby reducing vehicle acceleration at the primary stage of digging. In order to slow down the response to a change in load during digging operation, a constant indicating the response to a change in engine revolution is set small in proximity to a target engine revolution speed.