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