Phil Lucas made this early homemade ascender In his words (pers. comm. 2001):
I made this ascender while working at the Newport News Ship Building and Dry Dock Company, Virginia in 1965. It is constructed from a split heavy wall pipe nipple and three quarter inch steel plate for the cam. At the time I was unaware of any mechanical ascender and the design (such as it is) is entirely mine. Have you seen any other designs that squeeze the cam in this fashion? The foot or seat loop attachment is passed around the back of the ascender causing the cam to be pressed tightly against the rope. ...I tested the ascenders to ascend a 200-foot pit in Bull Cave, North Carolina. The worked just fine.
To answer Phil's question, no, I haven't seen other designs like this one. The way the rope acts to close the cam is interesting. Naturally, this ascender was to be used as a substitute for a Prusik knot, since the more efficient mechanical rigs were yet to be invented.
The steel construction makes this ascender rather heavy (but in the manila rope era, who cared?). Perhaps someone can work this idea into a lighter model and see if it has merit in today's world!
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©2007, Gary D. Storrick