Note that the carriage can move past the support members 19 to {HEAD ~ a position} at {TAIL ~ the left hand end} of the beam 
at
Note that the carriage can move past the support members 19 to { HEAD ~ a position } at { TAIL ~ the left hand end } of the beam
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH