Demotech, design for self reliance

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Make a pulley with means as found in a rural village

This construction manual-to-be will be worked on at the same time as new prototypes develop. There is already a long history of making prototypes for this design. Pictures taken from earlier 'news' items will tell this story. Also pictures will be taken from video footage taken at the site Keur Mousse in Senegal.
Recently Hanna Hemmink brought in photographs from her village in Senegal illustrating the present use of a pulley and the problems that may occur.

Pulleys as they are normally used in West Africa
This picture shows the normal use of pulleys for hoisting water. The women bring their own pulley, rope and bucket when fetching water from a communal well. The pulley is hooked to a beam, positioned over the well. To attach her pulley she has to lean against the superstructure of the well. As the area around the well may be muddy and therefore slippery, this is not a safe practice.
The working position when hauling water is leaning against the well with the lower body or the legs. The down-going part of the rope runs back into the well.
To speed up getting water from the well, sometimes (like in Indonesia) a small container or water bag is attached to each end of the rope.

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Pulleys as they function normally
This woman has just hooked her pulley to the support over the well. Now she works on laying the rope over the pulley wheel. There is no guide to keep the rope into the groove, so the rope can fall off when the pulley is carried around. But in actual use this is not a problem, as the groove is deep enough and the sides of the groove are smooth.
Pulleys can be bought at the local market in different sizes, the other woman uses a pulley with a smaller diameter wheel.

Detail of the problem with pulleys
This detail of the first picture shows the main problem with the traditional pulley: they wear out too quickly for the money they cost, even when locally made and marketed.
The wear is caused by the use of a steel pin as an axle, running in a (cast) steel pulley wheel. This causes fretting, indicated by its well known squeaking. Because of wear the axle gets thinner, not guiding the wheel properly. The wheel sags to one side and starts rubbing the frame, causing more friction and faster wear, Then it will soon fall apart and is beyond repair.
Separate pulley wheels, used for other purposes around the well, indicate this is a common problem.

The prototype pulley for Senegal
The first prototype developed by Demotech, shown here by Ives Faye. This prototype was taken by Ives and Reinder to Senegal in February 2003. It inspired at the intended test location in Keur Mousse a similar pulley with a larger diameter.