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