Preferably, the selector shaft 2 is driven by {HEAD ~ a brushless motor} 5 by means of a double planetary stage 6 and a toothed segment 7 which engages a toothed wheel 16 that is preferably positioned in {TAIL ~ a housing element} 17 
Preferably , the selector shaft 2 is driven by { HEAD ~ a brushless motor } 5 by means of a double planetary stage 6 and a toothed segment 7 which engages a toothed wheel 16 that is preferably positioned in { TAIL ~ a housing element } 17
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH