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