The ratchet wheel has an annular groove around the periphery, and a plurality of {HEAD ~ teeth} equiangularly spaced around {TAIL ~ the annular groove} 
The ratchet wheel has an annular groove around the periphery , and a plurality of { HEAD ~ teeth } equiangularly spaced around { TAIL ~ the annular groove }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL