An actuator engages the shaft for {HEAD ~ translation} from a first retracted position to {TAIL ~ a second extended position} 
to
An actuator engages the shaft for { HEAD ~ translation } from a first retracted position to { TAIL ~ a second extended position }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL