A gear box assembly for a twin rotor combine is provided. The gear box assembly includes a two speed gear box having a casing, an input shaft, an output shaft, and a two speed gear assembly housed within the casing and operatively connected between the input shaft and the output shaft. The gear box assembly also includes a splitter gear box operatively connected to the output shaft. The splitter gear box includes a housing, and a splitter gear assembly housed within the housing and configured to split a torque provided by the output shaft between a first output shaft and a second output shaft extending from the housing in a direction opposite a direction the output shaft extends from the two speed gear box. The two speed gear box is pivotable relative to the splitter gear box housing.

A clutch-controlled transfer gear having a drive shaft which is mounted so as to be rotatable by way of at least one drive shaft bearing, a primary shaft which is mounted so as to be rotatable by way of at least one primary shaft bearing, a secondary shaft which is arranged with an axial offset with respect to the drive shaft and which is mounted so as to be rotatable by way of at least one secondary shaft bearing, a transfer mechanism which is arranged between secondary shaft and drive shaft and bridges the axial offset thereof, and a clutch which is arranged between the drive shaft and an offset gear, by means of which clutch the secondary shaft is, for the operation thereof, coupled to the drive shaft and, for the deactivation thereof, decoupled from the drive shaft, as required.