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