a means for {HEAD ~ comparison} that compares {TAIL ~ a load detection value} obtained based upon detection signals from said load sensors with a predetermined overload value 
a means for { HEAD ~ comparison } that compares { TAIL ~ a load detection value } obtained based upon detection signals from said load sensors with a predetermined overload value
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH