{TAIL ~ Engagement} between {HEAD ~ the worm screw} 167 and the helical wheel 168 is maintained by the action exerted by the pinion 151 
{ TAIL ~ Engagement } between { HEAD ~ the worm screw } 167 and the helical wheel 168 is maintained by the action exerted by the pinion 151
TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH