We found these pullies wear out fast, are concidered expensive and are not generally used. This is very different from the country side in Indonesia, where for wells of similar depth the use of pullies is general. For Demotech a reason to work on an alternative.
The Demotech design for such an alternative asks for a precisely cut ring, cut loose from the side wall of the tire, includng the metal wire reinforcement, that gives the ring its stifness. We had to find out how to cut it in an efficient way, without any danger for the worker cutting himself or his helper with the very sharp knive needed for cutting rubber.
We found a proper working position: the rubber ring is put around the knees. By spreading the legs outwards, the ring is kept in place while working on it with the knive. There is no need for a helper, as one hand of the worker is free to pull at the cut-away strip of rubber. Pulling with some force on this strip helps much to ease the cutting. Both of us found this an effective and comfortabel working position.
We prepare this design for manufacturing by local craftsman in Senegal and elsewhere. A sharp knife should then be about all the tooling needed.