{TAIL ~ Two electrical cables} of an articulated robot arm are in the form of helical cords which lengthen and shorten respectively during {HEAD ~ the rotation} of the arm 
{ TAIL ~ Two electrical cables } of an articulated robot arm are in the form of helical cords which lengthen and shorten respectively during { HEAD ~ the rotation } of the arm
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH