In a tubular shaft, the open of the shaft is also left open by the ball so that {HEAD ~ wires} or {TAIL ~ other materials} may be passed through the shaft 
In a tubular shaft , the open of the shaft is also left open by the ball so that { HEAD ~ wires } or { TAIL ~ other materials } may be passed through the shaft
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH