Abstract: A target-input-torque determination unit determines the target input torque on the basis of the transmission required horsepower. The target input torque is a target value for the torque to be inputted to a power-transmission device. A target-output-torque determination unit determines the target output torque, which is a target value for the torque to be outputted by the power-transmission device. A command-torque determination unit uses torque-balance information to determine command torque for the motor from the target input torque and the target output torque. The target-input-torque determination unit determines the upper limit of the target input torque on the basis of an upper-limit-target-input-torque line and the engine rotation speed. The upper-limit-target-input-torque line sets a value smaller than the target output torque of the engine determined using the engine required horsepower and the engine rotation speed for the upper-limit value of the target input torque.

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: The work implement requirement determination unit determines a work implement required horsepower on the basis of an operation amount of a work implement operating member and a hydraulic pressure of a hydraulic pump. A transmission requirement determination unit determines a transmission required horsepower on the basis of a vehicle speed and the operation amount of the accelerator operating member. An engine requirement determination unit determines an engine required horsepower on the basis of the work implement required horsepower and the transmission required horsepower. The required throttle determination unit determines a required throttle value based on an engine requirement.

Abstract: The power-transmission device has an input shaft, an output shaft, a gear mechanism, and a motor. The gear mechanism includes a plurality of planetary gear mechanisms and a mode-switching mechanism, and transmits the rotations of the input shaft to the output shaft. The mode-switching mechanism selectively switches the drive-power transmission path of the power-transmission device between a plurality of modes. The motor is connected to the rotating elements of the planetary gear mechanisms. A target-input-torque determination unit determines the target input torque, which is a target value for the torque to be inputted to the power-transmission device. The target-output-torque determination unit determines the target output torque, which is a target value for the torque to be outputted from the power-transmission device. The command-torque determination unit uses the torque balance information to determine torque commands to the motor from the target input torque and the target output torque.

Abstract: In a work vehicle, a controller controls an engine based on an engine torque curve for defining a relationship between an engine speed, an engine output torque, and an operation amount of an accelerator operation member. The controller controls the engine based on a first engine torque curve during torque conversion travel. The controller controls the engine based on a second engine torque curve during lockup travel. The engine output torque of the second engine torque curve is less than the engine output torque of the first engine to curve in at least a portion of a range of the engine speed when at least the operation amount of the accelerator operation member is a predetermined operation amount that is less than a maximum operation amount.

Abstract: A maintenance support system for a construction machine calculates the cumulative load of every component corresponding with the driving and working conditions of the construction machine by a load calculation means after simulating the driving and working conditions on the basis of production operating conditions by an operation simulation means, and forecasts the lifespan of the respective components by a lifespan calculation means on the basis of the cumulative load. Hence, a more accurate maintenance schedule can be established in comparison with a case where which component is to be maintained is determined on the basis of only the operating time.

Abstract: The present invention provides a maintenance support system for a construction machine that allows a components maintenance schedule to be accurately established. The system 1 calculates the cumulative load of every component corresponding with the driving and working conditions of the construction machine 3 by means of the load calculation means 13 after simulating the driving and working conditions on the basis of production operating conditions by means of the operation simulation means 12, and forecasts the lifespan of the respective components by means of the lifespan calculation means 14 on the basis of the cumulative load. Hence, a more accurate maintenance schedule can be established in comparison with a case where which component is to be maintained is determined on the basis of only the operating time as in the prior art. The possibility of an unexpected component anomaly occurring at an earlier stage than the predetermined lifespan can therefore be reduced.

Abstract: The present invention relates to a speed changing device for a hydraulic driving apparatus and a speed change control method thereof, which provide excellent controllability, traveling efficiency, and reliability without occurrence of cavitation. To this end, the device comprises a shifter selected position sensor (63a) for detecting a shift lever change, a motor rotational speed sensor (52) for detecting a rotational speed of a hydraulic motor (50), and a control device (60); and the control device (60) judges and controls either a powering control or a brake control, based on the change of the shift lever selection and on the comparison of the detected motor rotational speed with a memorized motor rotational speed. In addition, a two-stage back pressure valve (23) can be provided between a directional control valve (21) and an oil tank.

Abstract: A method of power transmission in a mechanical/hydraulic type transmission system, by which changeover is smoothly effected between hydraulic power transmission and mechanical power transmission is provided. To this end, there are provided a hydraulic power transmitting means, for transmitting a mechanical power (Pm), which has been converted by a hydraulic motor (42), to the outside (300) by the engagement of a clutch (A), and a mechanical power transmitting means for transmitting a mechanical power (Po) to the outside (300) by the engagement of a clutch (B). Upon changeover from hydraulic power transmission to mechanical power transmission, the releasing of the clutch (A) is performed after the engagement of the clutch (B) is started and before the engagement of the clutch (B) is completed.

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 hydraulically-actuated multi-step transmission is adapted to prevent the occurrence of engagement shocks of a direct-coupled or lock-up clutch associated with a torque converter. Downshifting is carried out once with the direct-coupled clutch (8) engaged when the vehicle is slowed toward a stop. This is followed by a further downshift with the accelerator released and the direct-coupled clutch disengaged.

Abstract: A method of automatically changing the speed of a self-propelled motor vehicle while supplying an adequate amount of cooling oil to a retarder during retarder operation, avoids unnecessary shifting even under conditions wherein an accelerator is released. The method of automatic speed change is so adapted as to move the shift points at each stage of speed to a higher vehicle-speed side as compared with normal driving.