{TAIL ~ Both sets} are stationary with respect to a transmission housing, i.e. there is no sliding motion of {HEAD ~ any gear} 
{ TAIL ~ Both sets } are stationary with respect to a transmission housing , i.e. there is no sliding motion of { HEAD ~ any gear }
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD