A system for and method of shifting a drive configuration of an all-terrain vehicle (ATV) is provided. The system includes a shifter assembly, a gear case, and a linkage assembly extending therebetween. The shifter assembly includes a trigger lever for receiving a mechanical user input, thereby moving the shifter assembly between a locked configuration and an unlocked configuration. The linkage assembly translates the user input to the gear case, thereby causing the gear case to shift between an engaged configuration and a disengaged configuration, respectively. A linkage biasing member provides mechanical flexibility between the shifter assembly and the gear case, facilitating shifting on the fly. The trigger lever is operated by toggling it from a rest position to a deployed position. Upon user release, the trigger lever is automatically returned to its rest position for future engagement by the user.

A control process including the following steps is executed. The control process includes, at the time of switching from series-parallel mode to series mode, a step of reducing an engine torque, a step of releasing a clutch, a step of reducing a reaction torque of a first rotary electric machine and a step of increasing a torque of a second rotary electric machine, and, when synchronization is started and a step of increasing a positive torque of the first MG, a step of starting engagement of a clutch, and, when a rotation speed of the first rotary electric machine and a rotation speed of an engine are synchronous with each other, a step of engaging the clutch.

A control process including the following steps is executed. The control process includes, at the time of switching from series-parallel mode to series mode, a step of reducing an engine torque, a step of releasing a clutch, a step of reducing a reaction torque of a first rotary electric machine and a step of increasing a torque of a second rotary electric machine, and, when synchronization is started and a step of increasing a positive torque of the first MG, a step of starting engagement of a clutch, and, when a rotation speed of the first rotary electric machine and a rotation speed of an engine are synchronous with each other, a step of engaging the clutch.

A transmission assembly for mounting to an external power-source includes an input shaft configured to receive power-source torque. The transmission assembly also includes an output member configured to transmit a transmission output torque to drive a load. The transmission assembly additionally includes a countershaft driven by and arranged parallel to the input shaft. The countershaft has a first gear-set rotatably mounted thereon and is configured to drive the output member. The transmission assembly also includes a second gear-set in mesh with the first gear-set and operatively connected to the output member. Furthermore, the transmission assembly includes an electric motor configured to be selectively connected to the input shaft via a first torque transfer device and to the output member via a second torque transfer device to thereby provide a variable electric motor internal torque input to the transmission assembly. A vehicle having such a transmission and power-source is also disclosed.