<p>The system (1) has accumulators (3) e.g. nickel metal hydride/lithium-ion accumulators, for storing and releasing power required for self-contained operation of the system. An electric motor (4) e.g. permanent magnet brushless direct current electric motor, generates a rotational movement transmitted by a mechanical transmission for the system. A controller (5) manages control of the motor and the accumulators. A casing (2) directly supports and secures the accumulators, the motor and the controller. The transmission has a plastic pinion and/or a belt that is not-reinforced by metal material.</p>
