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