Abstract: A diagnostic device diagnoses a hydraulic pressure control actuator which drives a line pressure control valve to regulate a pressure of hydraulic oil between upper and lower limit line pressures, so that the pressure approaches a predetermined target line pressure. The diagnostic device includes: an actual hydraulic pressure detection unit to detect an actual hydraulic pressure; a determination value setting unit to set a high pressure fixation determination value which is increased as the driving revolution rate is increased so as to substantially match a characteristic of the actuator at a time of high pressure fixation; and a fixation determination unit to determine high pressure fixation of the actuator when the actual hydraulic pressure substantially matches the high pressure fixation determination value with a difference between the target line pressure and the upper limit line pressure not lower than a predetermined value.

Abstract: A power machine can include a hydraulic drive system that includes an infinitely variable hydraulic drive motor. A run-time displacement of the hydraulic motor can be adjusted based on commanded travel speed or based on a output torque. In some case, the run-time displacement can be selected from one of a plurality of displacement ranges, such as a high range and a low range.

Abstract: A control system includes a transmission and a controller configured to receive a vehicle stop command; determine a ground speed; compare the ground speed to first and second predetermined speed thresholds; generate, when the ground speed exceeds the second predetermined speed threshold, a downshift command; generate, when the ground speed is greater than the first predetermined speed threshold and less than or equal to the second predetermined speed threshold, a shuttle shift command; determine, when the ground speed is less than or equal to the first predetermined speed threshold, if the transmission is operating in the first or second mode; select, upon determining the operating mode, a four-square clutch; and at least partially engage the selected four-square clutch to slow or stop the work vehicle.

Abstract: To provide a traveling control mechanism and a traveling control method capable of controlling a traveling mechanism taking into consideration operation contents of a remote control valve. The problem is solved by a traveling control mechanism comprising a remote control valve (21, 22, 23, 24), a pressure adjusting solenoid valve (61, 62), a setting mechanism (70), and a controller (60). The traveling mechanism (8) allows a traveling speed to be switched between a high speed and a low speed in accordance with an operation amount of the remote control valve (21, 22, 23, 24). An HST circuit (30) is provided with a pump (31, 32) and a traveling motor (33), the pump (31, 32) connects to a pilot line (41, 42, 43, 44) allowing a hydraulic oil supplied from the remote control valve (21, 22, 23, 24) to flow therethrough, a pressure sensor (45) is attached to the pilot line (41, 42, 43, 44), and a rotation sensor (65) is attached to the traveling motor (33).

Abstract: According to the present invention, there is provided a method of reducing output torque deficits during the launch of a vehicle having a continuously variable transmission, wherein the variator has an input connected to a prime mover and an output. The method comprises the steps of determining a rate of change of ratio in the transmission, and predicting a required motor speed ratio rate of change value of the variator on the basis of: (i) the determined rate of change of ratio in the transmission, and (ii) the configuration of the transmission. The speed of the variator output is adjusted so as to achieve the required motor speed ratio rate of change value.

Abstract: A pump control system and an abnormal processing and recovering method thereof are disclosed. The pump control system includes a pump; a motor mechanically connected to the pump; and a driving controller electrically coupled to the motor, and the driving controller configured to control a speed of the motor. The driving controller controls the speed of the motor to be varied in a multistage manner in response to an abnormal triggering event, so as to recover the pump control system to an originally set stable state. The abnormal triggering event is generated by at least one physical parameter when the pump control system is operated.

Abstract: A method for controlling a transmission device of a vehicle. The device includes a hydraulic transmission. The displacement of the hydraulic pump is controlled so that it delivers to the n hydraulic motors a constant flow that is proportional to the speed of the wheels rotated by the drive. The displacement control of the hydraulic pump is carried out by a correction constant and a correction variable. The correction variable is determined in real time. The correction constant includes the sum of a theoretical constant and an adjusted constant. The theoretical constant is defined according to the theoretical behaviour of the hydraulic transmission. The adjusted constant is defined and corrected when the vehicle is in predetermined conditions of use, in order to reflect the real state of the vehicle.

Abstract: A hydraulic motor assembly includes a flow controller, a displacement controller and a hydraulic motor. The flow controller controls the flow of hydraulic fluid through the hydraulic motor and the displacement controller controls motor displacement. The hydraulic motor converts the pressure and flow into angular displacement of a drive shaft. An electrical generator is connected to the motor drive shaft and provides electrical power to accommodate a varying electrical load. As the electrical load varies, the flow controller and displacement controller vary the flow and displacement of the hydraulic motor to vary the torque applied to the generator by the drive shaft so that the drive shaft rotates at a desired speed.

Abstract: A transmission arrangement for a travel drive, in particular a mobile machine, includes a first hydraulic machine configured to be coupled to a drive machine, and a second hydraulic machine having an adjustable second expulsion volume, the second hydraulic machine configured to be connected fluidically to the first hydraulic machine via a first working line and a second working line of the transmission arrangement. The second hydraulic machine configured to be coupled or is coupled to a manual transmission of the transmission arrangement. The manual transmission has at least two transmission stages, and coupling of the second hydraulic machine to the manual transmission has the result that a torque can be transmitted. The transmission arrangement further includes a control apparatus configured to reduce to zero or to nearly zero the second expulsion volume at least during a changeover from one transmission stage to another transmission stage of the manual transmission.

Abstract: A control apparatus for a vehicle drive-force transmitting apparatus that includes a gear mechanism and a continuously-variable transmission mechanism. The control apparatus determines whether there is a lower-gear-ratio setting request requesting a target gear ratio of the continuously-variable transmission mechanism to be set to a lower gear ratio that is lower than a highest gear ratio of the continuously-variable transmission mechanism. When it is determined that there is not a detection accuracy of a rotational speed of an output rotary member of the drive-force transmitting apparatus, the control apparatus sets the target gear ratio to the lower gear ratio if it is determined that there is the lower-gear-ratio setting request, and sets the target gear ratio to the highest gear ratio if it is determined that there is not the lower-gear-ratio setting request.

Abstract: A hydraulic machine, in particular for a transmission arrangement, has an adjustable displacement volume and an adjusting device configured to adjust the displacement volume. The adjusting device is connected to a control unit so that the adjusting device is configured to be actuated in accordance with a setpoint value of the displacement volume. A transmission arrangement includes the hydraulic machine. A method for controlling the transmission arrangement is disclosed.

Abstract: An electromechanical drive comprises an electrical machine (101a), an electrical power converter (103) for converting voltage of an external electrical system to voltage suitable for the electrical machine, and a gearbox (111a) for mechanically connecting the electrical machine to an actuator (112a) and capable of providing selectable transmission ratios between the electrical machine and the actuator. The electrical power converter comprises a controller for selecting one of the selectable transmission ratios at least partly on the basis of a) first data related to actual and/or desired torque-speed operating point of the actuator and b) second data related to functional properties of at least the electrical machine. Thus, the transmission ratio can be selected at least partly from the viewpoint of the electrical machine taking into account for example the most advantageous speed range and/or torque range of the electrical machine.

Abstract: The target input shaft torque determination unit determines a target input shaft torque. The target output shaft torque determination unit determines a target output shaft torque so that a deceleration force for decelerating the vehicle is generated on the output shaft of the power transmission device in a state in which connection and disconnection states of the forward travel clutch and the reverse travel clutch are maintained at the state before the start of the shuttle action when the shuttle action is started. The torque-balance information is stored in a storage unit and defines a relationship between the target input shaft torque and the target output shaft torque to achieve a balance of the torques of a power transmission device. The command torque determination unit uses the torque-balance information to determine torque commands for the motor from the target input shaft torque and the target output shaft torque.

Abstract: An electronic controller for a variable ratio transmission and an electronically controllable variable ratio transmission including a variator or other CVT are described herein. The electronic controller can be configured to receive input signals indicative of parameters associated with an engine coupled to the transmission. The electronic controller can also receive one or more control inputs. The electronic controller can determine an active range and an active variator mode based on the input signals and control inputs. The electronic controller can control a final drive ratio of the variable ratio transmission by controlling one or more electronic solenoids that control the ratios of one or more portions of the variable ratio transmission.

Abstract: A shuttle shifting method for a continuously variable transmission automatically selects a manner of shuttle shifting as a function of certain monitored conditions. As one alternative, the direction of operation of the transmission is changed prior to reducing the vehicle speed to zero, and tilt of a swash plate of the hydrostatic power unit of the transmission is held substantially constant, for achieving fast, smooth shifts at faster starting and ending vehicle speeds, without coming to a complete stop. In another alternative, for slower starting and ending speeds, or other conditions such as a temperature condition is present, the vehicle is stopped by changing swash plate angle before effecting a directional change of the transmission and the swash plate.

Abstract: A method for controlling a continuously variable ratio transmission is described. The method may include controlling a continuously variable ratio unit (“variator”) having rotary input and output members through which the variator is coupled between an engine and a driven component, the variator receiving a primary control signal and being constructed and arranged to exert upon its input and output members torques which correspond directly to the control signal. The method may also include determining a target engine acceleration, determining settings of the variator's primary control signal and of an engine torque control for providing the required engine acceleration and adjusting the control signal and/or the engine torque control based on these settings, predicting a consequent engine speed change, allowing for engine and/or transmission characteristics, and correcting the settings of the control signal and engine torque based on a comparison of actual and predicted engine speeds.

Abstract: A parking brake is controlled in concert with operation of a hydrostatic power unit of a continuously variable transmission, particularly when engaging, disengaging and shuttle shifting the transmission, to provide advantages, particularly when on hills. When particular commands are received, such as shifting to a non-moving position, the parking brake is automatically engaged to hold the vehicle position. A swash plate of the hydrostatic unit can be automatically positioned to anticipate the next command. If that command is received, the brake is automatically gradually or proportionally released and the transmission engaged to effect the commanded movement of the vehicle. If a different command is received, the brake remains engaged as the transmission is configured for the commanded movement, such that no machine movement results. Then the brake is automatically gradually or proportionally released and the transmission engaged to effect that commanded movement.

Abstract: A method is described for operating a vehicle fitted with a continuously variable transmission (CVT) and having a lever for varying the transmission ratio of the CVT to permit the vehicle operator to vary the vehicle wheel speed. In the invention, the transmission ratio of the CVT is limited to a value dependent upon at least one of the prevailing engine speed and the rate of change of the engine speed.

Abstract: A method for performing a shuttle shift with a continuously variable transmission of a work machine is disclosed. The method may generally include adjusting a swash plate angle of a hydrostatic power unit of the transmission in a first direction to reduce a travel speed of the work machine in an off-going direction, initiating a directional swap between an off-going directional clutch of the continuously variable transmission and an on-coming directional clutch of the continuously variable transmission while the work machine is traveling in the off-going direction and adjusting the swash plate angle of the hydrostatic unit in a second direction after the initiation of the directional swap to reduce slippage across the on-coming directional clutch, wherein the second direction is opposite the first direction.

Abstract: A method controls the power-transmission in a machine having a continuously variable transmission (CVT) and a power source operatively coupled together in a powertrain. The method regulates operation of the CVT with a retarding power limit in order to limit the amount of retarding power transferable from the powertrain to the power source. The retarding power may be utilized to decelerate or decrease the speed of the machine. The method may register an operator input signal indicative of a deceleration event from a plurality of possible deceleration events. The deceleration event is compared to a lookup table to determine if the retarding power limit should be adjusted. The method may adjust the retarding power limit in accordance with the comparison.

Abstract: A shuttle shifting method for a continuously variable transmission automatically selects a manner of shuttle shifting as a function of certain monitored conditions. As one alternative, the direction of operation of the transmission is changed prior to reducing the vehicle speed to zero, and tilt of a swash plate of the hydrostatic power unit of the transmission is held substantially constant, for achieving fast, smooth shifts at faster starting and ending vehicle speeds, without coming to a complete stop. In another alternative, for slower starting and ending speeds, or other conditions such as a temperature condition is present, the vehicle is stopped by changing swash plate angle before effecting a directional change of the transmission and the swash plate.

Abstract: A working vehicle control apparatus includes: a selection device that selects a power mode or an economy mode; a determination device that determines whether or not a speed restriction condition and a load pressure have been established; an engine rotational speed restriction device that restricts a maximum rotational speed of the motor upon selection of the economy mode to a lower speed side than a maximum rotational speed of the motor upon selection of the power mode when it is determined that the speed restriction condition has been established; and a vehicle speed restriction device that restricts a maximum vehicle speed upon selection of the economy mode to a lower speed side than a maximum vehicle speed upon selection of the power mode when it is determined that a speed restriction condition has not been established.

Abstract: A tractor has an engine which drives the tractor via a transmission whose operative ratio is controlled electronically. The tractor also has an auxiliary hydraulic fluid supply system with an engine driven hydraulic pump which provides pressurized fluid to one or more auxiliary outlets on the tractor. A driver operated control means is provided for selecting the oil flow rate to be delivered to the outlets, and a control system adjusts the speed of the engine to the minimum required to provide the selected oil flow rate and changes the operative ratio of the tractor transmission so that the speed of the tractor remains substantially unchanged despite any change in engine speed required to deliver the selected oil flow rate. The transmission may be a CVT or powershift transmission.

Abstract: A method is provided for controlling a gear ratio change in a hydrostatic drive machine. The hydrostatic drive machine includes a variable displacement pump and at least one variable displacement motor fluidly connected with the variable displacement pump. The method includes a step of determining a gear ratio rate of change corresponding to a change from a current gear ratio to a new gear ratio. Start and stop overlap gear ratios corresponding to the gear ratio rate are determined and define an overlap range. The current gear ratio is changed to the new gear ratio using electronic signals at least in part by simultaneously changing displacements of the variable displacement pump and the at least one variable displacement motor at gear ratios within the overlap range, and sequentially changing displacements of the variable displacement pump and the at least one variable displacement motor at gear ratios outside the overlap range.

Abstract: The disclosure is directed to a method for use in a machine having a transmission having an operational mode, and including first and second power source paths, and a combined power output. The first power source path includes a variator. The method of controlling the transmission includes operating the first power source path, providing a signal indicative of the operational mode of the transmission to a controller, and at least partially neutralizing the variator if the signal indicates that the transmission is in neutral for at least a preset period of time.

Abstract: One disclosed embodiment relates to a propulsion system for a machine. The propulsion system may include a prime mover operatively connected through a continuously variable transmission to a propulsion device. The propulsion system may also include propulsion-system controls that control an operating parameter of the continuously variable transmission, which may include adjusting the operating parameter based on operator input. Controlling the operating parameter may also include determining an adjustment limit for the operating parameter based on one or more operating conditions and applying the adjustment limit to the operating parameter to modify at least one of acceleration and jerk of the machine based on the one or more operating conditions.

Abstract: A method for controlling an automated clutch, which comprises a hydraulic clutch actuating system having a hydrostatic actuator, the pressure of which is detected. The method includes using the pressure of the hydrostatic actuator to adapt the characteristic curve of the clutch.

Abstract: A pump arrangement for fluid in an automotive transmission system includes, but is not limited to a first, low-pressure pump stage and a second, high-pressure pump stage, the first pump stage supplying low-pressure fluid to a lubrication/cooling system and to the inlet of second pump stage, which supplies high pressure fluid to a hydraulic control system. Fluid from both systems is returned via a reservoir and filter to the first pump stage.

Abstract: A method and system provides a Brake Transmission Shift Interlock Override mode in a vehicle including a shift-by-wire transmission. With power applied and ignition on, a driver will press and hold an override switch for a calibrated time. While the override switch is pressed, the driver presses a non-Park button for another calibrated time. The result will be that the vehicle is placed in the selected range wherein the transmission will not automatically shift to Park upon detecting a triggering event. The driver is able to shift the vehicle from Park, even if an electrical failure prevents the transmission from shifting out of Park. As such the vehicle can be driven until the failure is serviced.

Abstract: A speed ratio of a continuously variable transmission mechanism 20 is increased when a speed ratio of a subtransmission mechanism 30 connected in series to the continuously variable transmission mechanism 20 is switched from a first speed to a second speed. When an excess rotation speed Nb obtained by subtracting a target rotation speed from an engine rotation speed Ne exceeds a determination value Nr1 during this shifting process, a rapid rotation increase in an internal combustion engine 1 is prevented by reducing a shift speed of the continuously variable transmission mechanism 20 (S105A).

Abstract: A coast stop vehicle for automatically stopping a drive source when a predetermined condition holds during the travel of the vehicle includes a drive source control unit adapted to control the automatic stop and the restart of the drive source, a transmission mechanism provided between the drive source and drive wheels, and a transmission control unit adapted to control a speed ratio of the transmission mechanism. When the drive source is restarted, the transmission control unit is adapted to control the transmission mechanism to a speed ratio higher than a predetermined speed ratio in response to an input shift request to the predetermined speed ratio, and the drive source control unit is adapted to restart the drive source in a state where the speed ratio of the transmission mechanism is higher than the predetermined speed ratio.

Abstract: A method of controlling a dual-clutch transmission in a motor vehicle, including two partial drivetrains, each having a plurality of gears, which each can be connected to a crankshaft of an internal combustion engine by a friction clutch, the method having the following steps: the first friction clutch transmits a torque to the first partial drivetrain assigned to it; the second friction clutch transmits at most a negligible torque to the second partial drivetrain; and the two partial drivetrains have a common differential, where when there are changes in torque and the amount of torque to be transmitted is low, and there is downshifting into a gear with a high transmission ratio in the first partial drivetrain, downshifting occurs into a gear with a low transmission ratio in the second partial drivetrain, and preliminary torque is applied to the differential by this gear.

Abstract: A method for actuating a clutch in the drive train of a motor vehicle, including: generating a respective position setpoint for each predetermined target interval to actuate the clutch; in each predetermined target interval, actuating the clutch in a plurality of predetermined controller sampling intervals; discretizing a respective position setpoint change into a plurality of intermediate position setpoints; determining a number of intermediate position setpoints in the plurality of intermediate position setpoint depending on the ratio of the target interval to the controller sampling interval; and specifying the respective position setpoint changes in steps to actuate the clutch.

Abstract: A tractor has an engine (11) which drives the tractor via a transmission (14) whose operative ratio is controlled electronically. The tractor also has an auxiliary hydraulic fluid supply system with an engine driven hydraulic pump (17) which provides pressurised fluid to one or more auxiliary outlets (18-21) on the tractor. A driver operated control means (22, 23) is provided for selecting the oil flow rate to be delivered to the outlets, and a control system (25) adjusts the speed of the engine to the minimum required to provide the selected oil flow rate and changes the operative ratio of the tractor transmission so that the speed of the tractor remains substantially unchanged despite any change in engine speed required to deliver the selected oil flow rate. The transmission may be a CVT or powershift transmission.

Abstract: When an accelerator pedal opening angle is large, a target vehicle speed is calculated using a read-ahead vehicle speed and, when the accelerator pedal opening angle is small, the target gear shift ratio is calculated using an actual vehicle speed.

Abstract: One disclosed embodiment relates to a propulsion system for a machine. The propulsion system may include a prime mover operatively connected through a continuously variable transmission to a propulsion device. The propulsion system may also include propulsion-system controls that control an operating parameter of the continuously variable transmission, which may include adjusting the operating parameter based on operator input. Controlling the operating parameter may also include determining an adjustment limit for the operating parameter based on one or more operating conditions and applying the adjustment limit to the operating parameter to modify at least one of acceleration and jerk of the machine based on the one or more operating conditions.

Abstract: A system and method of dithering speed and/or torque for shifting a transmission of a vehicle having an engine, a reversible, variable displacement hydraulic motor/pump which can be driven by the engine, a hydraulic accumulator supplied by said motor/pump, and at least one reversible hydraulic driving motor for propelling the vehicle supplied with fluid by the hydraulic accumulator and/or by said motor/pump operating as a pump. A transmission unit connects the engine with the variable displacement hydraulic motor/pump during a first mode of operation (city mode) and connects the engine to a vehicle drive wheel during a second mode of operation. The system utilizes stored hydraulic energy to dither the output of the driving motor in order to achieve quick and smooth shifts between city and highway mode, or between various ranges within the city mode.

Abstract: A method for operating a motor vehicle hybrid powertrain having an engine, a motor-generator and a multi-speed automatically-shiftable transmission, wherein the engine and the motor-generator operate to supply torque to the transmission for driving a vehicle. The method includes modulating the torque supply from the motor-generator to the transmission during a gear shift to minimize a transmission output torque disturbance.

Abstract: A first motor 3 and a second motor 4 of variable displacement type are in parallel to each other connected to a hydraulic pump 2 in a closed circuit, through which the output torque from the first motor 3 is transmitted to an output shaft 6. A clutch control unit 10 controls a clutch device 15 as: when the engine speed is N1, which is the case where the accelerator pedal is fully depressed, the clutch is disengaged at the vehicle speed v1. When the engine speed is N3(<N1), which is the case where the accelerator pedal is half depressed, the clutch is disengaged at the vehicle speed v3(<v1).

Abstract: A control system for an automatic transmission includes a downshift control section configured to increase an engaging capacity of an engaging-side engaging element to engage the engaging-side engaging element and decrease a first engaging capacity of a disengaging-side engaging element to disengage the disengaging-side engaging element when a parameter representing a progressing condition of the downshift reaches a value, thereby carrying out the downshift in a power-on condition. Additionally, the downshift control section is configured to decrease the engaging capacity of the disengaging-side engaging element to a second engaging capacity smaller than the first engaging capacity to continue the downshift which is currently progressing and to cause the engine control section to continue controlling the engine speed when a power-off condition is detected upon an accelerator pedal being returned to a position representing an operating amount during the downshift.

Abstract: A hydraulic control system for a automatic transmission includes a plurality of solenoids and valves in fluid communication with a plurality of shift actuators. The shift actuators are operable to actuate a plurality of torque transmitting devices. Selective activation of combinations of the solenoids allows for a pressurized fluid to activate at least one of the shift actuators. The solenoids are configured to provide a forward gear ratio and a reverse gear ratio when the solenoids are deengerized.

Abstract: A load control structure for a work vehicle comprises: set rotation speed detection device for detecting a set rotation of an engine of the work vehicle; actual rotation speed detection device that senses an actual rotational speed of the engine; continuously variable speed change device that receives power from an engine of the work vehicle; speed change position detecting device for detecting a speed change operation position of the continuously variable speed change device; operating device for speed-shifting the continuously variable speed change device; control device for controlling the operation of the operating device; wherein the control device calculates a drop amount of the actual engine rotation speed from the set rotation speed based on the detected information from the set rotation speed detection device and the actual rotation speed detection device, and sets a limit operation position for the continuously variable speed change device based on the calculated drop amount and a correlation data t

Abstract: In an engine load control device of a work vehicle, an output of an engine is transmitted to a hydraulic actuator via a variable displacement type hydraulic pump. A controller is configured to calculate, based on a target rotational speed of the engine detected by a target rotational speed detecting portion and an actual rotational speed of the engine detected by an actual rotational speed detecting portion, a variation rate per unit time of a difference between the detected results, and to adjust the maximum absorbing torque of the hydraulic pump according to the magnitude of the variation rate.

Abstract: A transmission has an input member and an output member, first and second intermediate shafts having substantially identical gear sets with gears concentric with and selectively connectable for rotation with the first and second intermediate shafts, respectively. Output gears are concentric with and rotatable with the output member and mesh with the substantially identical gear sets. First and second torque-transmitting devices are operable for transmitting torque from the input member to the first and second intermediate shafts, respectively. Torque-transmitting mechanisms are mounted concentric with, rotatable about and selectively engagable with the gears mounted on the intermediate shafts. A controller is operatively connected to the torque-transmitting mechanisms and to at least one of the torque-transmitting devices.

Abstract: An engine load control device is adapted to a working vehicle in which output of an engine is transmitted to drive wheels and to hydraulic actuators including a working equipment hydraulic actuator via a plurality of variable capacity hydraulic pumps. The control device includes an engine speed detection unit that detects an engine speed, an instruction content detection unit that detects contents of instructions of a speed instruction device, a hydraulic pump load detection unit that detects load of at least one load detection hydraulic pump among the variable capacity hydraulic pumps, and an absorption torque control unit. The absorption torque control unit controls absorption torque of at least one control hydraulic pump other than the load detection hydraulic pump based on detection results of the engine speed detection unit, the instruction content detection unit, and the hydraulic pump load detection unit.

Abstract: A work machine includes an IC engine having an output, an IVT having an input coupled with the IC engine output, and a ground speed actuator. A desired speed sensor associated with the ground speed actuator provides an output signal indicating a slower ground speed. At least one electrical processing circuit is configured for increasing an input/output (I/O) ratio of the IVT, dependent upon the sensor output signal, such that a net torque transfer back-driven from the IVT input to the IC engine output is substantially zero.

Abstract: A work vehicle includes a hydraulic stepless speed changing apparatus and a gear type speed changing apparatus operable to receive output from the hydraulic stepless speed changing apparatus to convert it into a plurality of stages of speed. A return oil passage connected to a high-pressure side circuit of the hydraulic stepless speed changing apparatus is connected to a hydraulic tank. The return oil passage incorporates an unload valve and a throttle valve, between which an operably coupling mechanism is provided. This operably coupling mechanism switches over the unload valve to an unload condition in response to an operational displacement of a brake operating member for operating a brake to its braking side.

Abstract: A load control structure for a work vehicle comprises: set rotation speed detection device for detecting a set rotation of an engine of the work vehicle; actual rotation speed detection device that senses an actual rotational speed of the engine; continuously variable speed change device that receives power from an engine of the work vehicle; speed change position detecting device for detecting a speed change operation position of the continuously variable speed change device; operating device for speed-shifting the continuously variable speed change device; control device for controlling the operation of the operating device; wherein the control device calculates a drop amount of the actual engine rotation speed from the set rotation speed based on the detected information from the set rotation speed detection device and the actual rotation speed detection device, and sets a limit operation position for the continuously variable speed change device based on the calculated drop amount and a correlation data t

Abstract: Methods and systems are provided for pressurizing a transmission hydraulic circuit including a transmission mechanical pump coupled to an engine though a gearbox. One example method comprises, during an engine start, adjusting a speed ratio between the transmission pump and the engine between a first speed ratio and a second speed ratio, the pump rotating faster relative to the engine at the first speed ratio as compared with the second speed ratio.

Abstract: A method for operating a multi-speed automatic transmission of a motor vehicle. The automatic transmission has multiple shift elements for transmitting torque and/or power. When in forward and reverse gears, a first number of shift elements are engaged, and a second number of shift elements are disengaged. To improve the shift speed of successive upshifts and/or successive downshifts which are implemented in an overlapped manner, during a first upshift and/or downshift, at least one shift element, necessary for a successive second upshift and/or downshift, is prepared during the first upshift and/or downshift such that when the first upshift and/or downshift reaches a synchronous point, immediate implementation of the successive second upshift and/or downshift is possible. Depending on a gear change to be implemented, the first upshift and/or downshift from a current gear to a desired gear is preferably implemented as a multiple shift rather than a single shift.