In {TAIL ~ the embodiment} shown, {HEAD ~ elastic coupling member} 13 is formed as a spring member 
In { TAIL ~ the embodiment } shown , { HEAD ~ elastic coupling member } 13 is formed as a spring member
REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH