The invention relates to a speed changer which comprises an input shaft axis (4), a first input shaft (EW1) and a second input shaft (EW2) arranged on the input shaft axis (4), a first intermediate shaft axis (5) and a second intermediate shaft axis (6) spaced apart from the input shaft axis (4), a first intermediate shaft (VW1) arranged on the first intermediate shaft axis (5) and a second intermediate shaft arranged on the second intermediate shaft axis (6), wherein the first input shaft and / or the second input shaft connects with the first intermediate shaft and / or the second intermediate shaft via an intermediate gear stage to form a gear shifting stage, and the intermediate gear stage accesses power flow through a shifting means and can be switched off. The speed changer comprises a special gear stage (R5), which can be switched selectively to access power flow of a first sub-speed changer or a second sub-speed changer, and at least one gear shifting stage is formed as a winding energy buffer when the special gear stage is accessed.