Patent ID: 8066617

Claim:
A method for controlling an automated step-down transmission (CT), the automated step-down transmission (CT) being arranged in a drivetrain of a motor vehicle, between either a drive engine or a hybrid drive and an drive axle, and comprising at least a multi-stage main transmission (HG) and a range group (GP) connected downstream from the main transmission (HG), the main transmission (HG) has an intermediate transmission configuration and at least one countershaft (W VG1 ) that is engaged by a transmission brake (Br), an input shaft (W GE ) being connected, via a controllable separator clutch (K), to the drive engine or the hybrid drive, the main transmission (HG) being shiftable without synchronization and the range group (GP) being shifted, after synchronization, such that during a range shift, a transmission ratio step (R) that is engaged in the main transmission (HG), before the range shift, remains engaged after the range shift, the method of controlling the step-down transmission (CT) during the range shift comprising the steps of: reducing a load, which is transmitted by the step-down transmission (CT), by reducing torque that is outputted by the drive engine or the hybrid drive; disengaging a current ratio step (L; S) that is engaged in the range group (GP=N) before the range shift was initiated; synchronizing a target ratio step (S; L) in the range group (GP) that is an objective of the range shift, during a range downshift, by appropriately controlling the torque that is outputted by the drive engine or the hybrid drive and, if necessary, at least partially engaging the separator clutch (0<K≦1); engaging the target ratio step (S; L) in the range group (GP); and increasing the load, which is transmitted by the step-down transmission (CT), by increasing the torque that is output by the drive engine or the hybrid drive.