The guide arm has a mount for fitting {TAIL ~ said machine tool} and {HEAD ~ said housing} has at least one top track wheel, at least one side track wheel and at least one oblique track wheel adapted for rolling along the top, side and edge of the elongate track, respectively 
The guide arm has a mount for fitting { TAIL ~ said machine tool } and { HEAD ~ said housing } has at least one top track wheel , at least one side track wheel and at least one oblique track wheel adapted for rolling along the top , side and edge of the elongate track , respectively
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