It is evident that {TAIL ~ operation} of the motor drives the weight carriage in a desired direction along the beam to vary the load imposed by {HEAD ~ the machine} 
It is evident that { TAIL ~ operation } of the motor drives the weight carriage in a desired direction along the beam to vary the load imposed by { HEAD ~ the machine }
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD