The metallic parts 11 and 21 thus brought close to each other will attract each other owing to the magnetic attraction of the magnets 14 and 24, with the result that {HEAD ~ the projection} 26 on the metallic part 21 automatically engages {TAIL ~ the groove} 16 in the metallic part 11, so that the coupling operation can be completed instantaneously 
automatically engages
The metallic parts 11 and 21 thus brought close to each other will attract each other owing to the magnetic attraction of the magnets 14 and 24 , with the result that { HEAD ~ the projection } 26 on the metallic part 21 automatically engages { TAIL ~ the groove } 16 in the metallic part 11 , so that the coupling operation can be completed instantaneously
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH