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