a motion device for effecting {TAIL ~ relative movement} between said carriage and {HEAD ~ a friction surface} in a first direction 
a motion device for effecting { TAIL ~ relative movement } between said carriage and { HEAD ~ a friction surface } in a first direction
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH