A method for shift control of an automated auxiliary transmission that is mounted in a drive train of a motor vehicle between a drive motor (AM) and a final drive, and includes at least one multi-step main gearing (HG) and one two-step front-mounted group (VG) connected upstream of the main gearing (HG), and with which the main gearing (HG) can be shifted via unsynchronized clutches and the front-mounted group can be shifted via synchronized clutches. Depending on the currently existing driving or operating situation, a gear change is performed in the auxiliary transmission through a change in the transmission ratio step (G1, G2, G3) of the main gearing (HG) while maintaining the currently engaged transmission ratio step (K1, K2) in the front-mounted group (VG).

A transmission which includes input and output shafts and first and second step-down devices for producing various step-down ratios. The first and second step-down devices are associated with first and second controllable clutches, respectively, in order to connect, in a torque-transmitting manner, the respective step-down device between the input shaft and the output shaft. A first gear of the transmission is obtained by actuating the first clutch and a second gear by actuating the second clutch. A method of controlling a gearshift, from the first gear to the second gear, includes the steps of determining operating condition parameters of the transmission; and determining optimized degrees of actuation of the clutches by a search process related to a transmission model that determines the degrees of actuation on the basis of operating condition parameters in relation to a predetermined optimization criterion. The transmission model is based on slip.

A continuously variable powertrain device for a work vehicle includes a hydraulic static transmission to output a continuously shifted motive power while continuously varying a velocity of a motive power received from an engine, a planetary transmission to receive the motive power from the engine and the continuously shifted motive power and to output a compound motive power, a pressure detector to detect a hydraulic pressure in a closed circuit of the hydraulic static transmission, a planetary clutch mechanism to switch a shift level of the planetary transmission, and a powertrain controller to control actuation of the hydraulic static transmission and the planetary transmission based on a shift command.

A transmission which includes input and output shafts and first and second step-down devices for producing various step-down ratios. The first and second step-down devices are associated with first and second controllable clutches, respectively, in order to connect, in a torque-transmitting manner, the respective step-down device between the input shaft and the output shaft. A first gear of the transmission is obtained by actuating the first clutch and a second gear by actuating the second clutch. A method of controlling a gearshift, from the first gear to the second gear, includes the steps of determining operating condition parameters of the transmission; and determining optimized degrees of actuation of the clutches by a search process related to a transmission model that determines the degrees of actuation on the basis of operating condition parameters in relation to a predetermined optimization criterion. The transmission model is based on slip.

A method for shift control of an automated auxiliary transmission that is mounted in a drive train of a motor vehicle between a drive motor (AM) and a final drive, and includes at least one multi-step main gearing (HG) and one two-step front-mounted group (VG) connected upstream of the main gearing (HG), and with which the main gearing (HG) can be shifted via unsynchronized clutches and the front-mounted group can be shifted via synchronized clutches. Depending on the currently existing driving or operating situation, a gear change is performed in the auxiliary transmission through a change in the transmission ratio step (G1, G2, G3) of the main gearing (HG) while maintaining the currently engaged transmission ratio step (K1, K2) in the front-mounted group (VG).

A transmission controller executes synchronization shift of shifting a variator in a direction opposite to a speed ratio change direction of a sub transmission mechanism when shifting a sub transmission mechanism. When a gear position of the sub transmission mechanism is at the second gear position and an output increase request of a power source is made, the transmission controller prohibits the synchronization shift and shifts only the sub transmission mechanism from a second gear position to a first gear position.