A rotary-linear unit from whose front end the operative section of a output drive part projects. This output drive part is drivingly connected both with a linear drive and with an oscillating vane motor. The oscillating vane motor is associated with the rear end of the rotary-linear unit, the linear drive being arranged between the oscillating vane motor and the operative section of the output drive rod. This leads to an assembly which is extremely compact both in the axial direction and also in the radial direction.