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