A transmission includes an input shaft coupled to a prime mover, a countershaft, main shaft, and an output shaft, with gears between the countershaft and the main shaft. A shift actuator selectively couples the input shaft to the main shaft by rotatably coupling gears between the countershaft and the main shaft. The shift actuator is mounted on an exterior wall of a housing including the countershaft and the main shaft. An integrated actuator housing includes a single external power access for the shift actuator. A controller interprets a shaft displacement angle, determines if the transmission is in an imminent zero or zero torque region, and performs a transmission operation in response to the transmission in the imminent zero or zero torque region.

A method of controlling an automatic transmission is provided. The automatic transmission includes first and second frictional engageable elements and a hydraulic mechanism. The method includes controlling a first hydraulic pressure control valve of the first element to adjust hydraulic pressure to a given value in a first period in response to the gear shift command and increase the hydraulic pressure until first friction plates engaged in a second period, and a second hydraulic pressure control valve of the second element to pre-charge in response to the gear shift command, maintain the hydraulic pressure at a lower value than a highest target value immediately after the pre-charging, and increase the hydraulic pressure until second friction plates engaged immediately after the maintaining the pressure, a time length of the first period being shorter than a time length between a start of the pre-charging and a start of the increasing the pressure.

A method of controlling an automatic transmission is provided. The automatic transmission includes first and second frictional engageable elements and a hydraulic mechanism. The method includes controlling a first hydraulic pressure control valve of the first element to adjust hydraulic pressure to a given value in a first period in response to the gear shift command and increase the hydraulic pressure until first friction plates engaged in a second period, and a second hydraulic pressure control valve of the second element to pre-charge in response to the gear shift command, maintain the hydraulic pressure at a lower value than a highest target value immediately after the pre-charging, and increase the hydraulic pressure until second friction plates engaged immediately after the maintaining the pressure, a time length of the first period being shorter than a time length between a start of the pre-charging and a start of the increasing the pressure.

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying/discharging hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying/discharging hydraulic pressure to/from the chambers, and first and second oil paths communicating the valve with the chambers. The second surface has a larger area for receiving hydraulic pressure than the first surface. The method includes controlling the disengaged friction plates to be engaged by adjusting the hydraulic pressure to a first pressure in a first period in response to a gear shift command and adjusting the hydraulic pressure to a second pressure in a second period. The first pressure is changed depending on a state of the automatic transmission.

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying/discharging hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying/discharging hydraulic pressure to/from the chambers, and first and second oil paths communicating the valve with the chambers. The second surface has a larger area for receiving hydraulic pressure than the first surface. The method includes controlling the disengaged friction plates to be engaged by adjusting the hydraulic pressure to a first pressure in a first period in response to a gear shift command and adjusting the hydraulic pressure to a second pressure in a second period. The first pressure is changed depending on a state of the automatic transmission.

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying and discharging hydraulic pressure to and from the chambers, and first and second oil paths communicating the valve with the chambers. The second surface has a larger area for receiving hydraulic pressure than that of the first surface. The method includes controlling the friction plates to change from the disengaged state to the engaged state. Controlling the friction plates includes adjusting the hydraulic pressure to a first instruction pressure in a first period in response to a gear shift command, and to a second instruction pressure in a second period.

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying and discharging hydraulic pressure to and from the chambers, and first and second oil paths communicating the valve with the chambers. The second surface has a larger area for receiving hydraulic pressure than that of the first surface. The method includes controlling the friction plates to change from the disengaged state to the engaged state. Controlling the friction plates includes adjusting the hydraulic pressure to a first instruction pressure in a first period in response to a gear shift command, and to a second instruction pressure in a second period.

A method for rocking a vehicle free. The vehicle comprises a drive aggregate (2), a transmission (4), shifting elements (10), and a starting element (5). The rocking free process is carried out as a function of actuation of an accelerator pedal (11) by the driver or a torque delivered by the drive aggregate (2) as a function of the actuation of the accelerator pedal. The shifting element (10) is controlled such that reduced actuation of the accelerator pedal or reduced torque delivered by the drive aggregate (2), reduces a control pressure of the shifting element (10) of the transmission (4) down to a filling pressure or a pressure that corresponds to the filling pressure, and increased actuation of the accelerator pedal or increased torque delivered by the drive aggregate (2), increases the control pressure of the shifting element (10) and the shifting element is operated in a slipping mode.

A method for rocking a vehicle free. The vehicle comprises a drive aggregate (2), a transmission (4), shifting elements (10), and a starting element (5). The rocking free process is carried out as a function of actuation of an accelerator pedal (11) by the driver or a torque delivered by the drive aggregate (2) as a function of the actuation of the accelerator pedal. The shifting element (10) is controlled such that reduced actuation of the accelerator pedal or reduced torque delivered by the drive aggregate (2), reduces a control pressure of the shifting element (10) of the transmission (4) down to a filling pressure or a pressure that corresponds to the filling pressure, and increased actuation of the accelerator pedal or increased torque delivered by the drive aggregate (2), increases the control pressure of the shifting element (10) and the shifting element is operated in a slipping mode.

A transmission structure of the present invention causes, during a period from a time point when a rotational speed of a drive rotational power reaches a predetermined first/second speed stage shift-up start speed until a first/second speed stage shift-up end time point, one of an input-side clutch mechanism pair and an output-side clutch mechanism pair to be in a double transmitting state, and causes, in the double transmitting state, a first clutch mechanism and a second clutch mechanism of the other one of the input-side clutch mechanism pair and the output-side clutch mechanism pair to be shifted to a disengagement sate and an engagement state, respectively, while having frictional plate slid.