M06. Double Screw of Napier
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This machine should be familiar to all fishermen, because it is the basis of the "level-winding reel."

It is basically a cylindrical can with a helical groove, having the follower made of elongated form so that it can pass the junctures of the grooves, and also such that said follower can pivot about its own axis so that reversal may be effected at the ends.

Reference :
Loeffler, Kent (Technician)