{HEAD ~ The relative dimensions} of the lever arms are such that when the switching tube is in {TAIL ~ the off position}, an opening force cancels a switching on closing force 
{ HEAD ~ The relative dimensions } of the lever arms are such that when the switching tube is in { TAIL ~ the off position } , an opening force cancels a switching on closing force
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH