Patent ID: 7290460

Claim:
An electro-pneumatic switching unit for a vehicle transmission ( 6 ) comprising; a splitter group transmission ( 12 ) pneumatically switched via a first set of valves ( 36 , 38 ); a range-change group transmission ( 14 ) pneumatically switched via a second set of valves ( 44 , 46 ), and switching of which can be manually preselected by a vehicle driver via a gear lever ( 16 ); a mechanical locking device ( 54 , 56 ) for mechanically preventing the manual switching of inadmissible reduction ratios of a vehicle transmission ( 6 ); a prevention device ( 30 , 42 , 64 ) for preventing pneumatic switching of the inadmissible reduction ratios of the vehicle transmission ( 6 ); and an electronic control device ( 20 ), wherein the mechanical locking device ( 54 , 56 ), which prevents the vehicle transmission from performing the manual switching of inadmissible reduction ratios of the vehicle transmission ( 6 ), is pneumatically actuated by a first valve ( 44 ) of the second set of valves ( 44 , 46 ) for switching the range-change group transmission ( 14 ) according to a gear ratio range of the second set of valves ( 44 , 46 ).