{TAIL ~ The support unit} has a receiving portion, a biasing member, and {HEAD ~ a braking unit} 
{ TAIL ~ The support unit } has a receiving portion , a biasing member , and { HEAD ~ a braking unit }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD