If {HEAD ~ this embodiment} is equipped with {TAIL ~ a drive} 14, the force of the drive 14 can reinforce the spring 23 
is equipped with
If { HEAD ~ this embodiment } is equipped with { TAIL ~ a drive } 14 , the force of the drive 14 can reinforce the spring 23
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH