{HEAD ~ The coupler} preferably comprises a compliant belt and pulley drive, {TAIL ~ a worm and gear drive}, or a bevel gear drive 
comprises
{ HEAD ~ The coupler } preferably comprises a compliant belt and pulley drive , { TAIL ~ a worm and gear drive } , or a bevel gear drive
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH