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