latching mechanism 26 that is situated on the belt pulley 14 the axial ends of the drum have two toothed rings 28 that are shaped into the peripheral surface at an axial distance from each other and on which the toothed belts 22 24 run the toothed belts 22 24 are tightened around the drum 20 and the pinion shaft 18 by means of a shared adjustable tension roller 30 the axes of the direct current motor 10 of the belt pulley 14 and of the pinion shaft 18 which is coaxial thereto as well as the drum are parallel they can also lie in one shared plane the reduction gear made up of the two stage belt drive has an efficiency of over 80 the brushless direct current motor 10 whose rotor configured as an external rotor is equipped with a neodymium magnetic ring develops a high starting torque of for example up to 2 nm this combination enables the drive unit to achieve extremely short actuation times in the range of less than one half second the latching mechanism 26 consists of two ratchets 32 that are situated diametrically opposed on the circumference of the belt pulley 14 u2014 one of said ratchets 32 being shown in fig1 u2014 and of.