Gearbox for a hybrid vehicle

The gearbox for a hybrid drive motor vehicle has a first main drive shaft (X,X') driven by the internal combustion engine (1) and a secondary drive shaft (Y,Y') to receive the drive. A secondary main shaft (Z,Z') is driven for rotation by the electric motor (2) and via a transmission. The secondary main shaft has a driven shaft (7,8) with a gear (70) for rotary coupling with the secondary drive shaft. The transmission allows drive from the electric motor to the driven shaft directly or via a step down ratio.