The Bicycle Wheel Rope Pump
Invented, as far as I know, by members of an NGO working in Senegal, the rope pump is incredibly simple and can be made very cheaply indeed. I went to a bit more effort with this one because I wanted it to look cool as well. The two bicycle wheels came from the rubbish market in Essaouira, as did the handle, which is from a table-top meat grinder. The bottom part of the pump, the bit in the water, is a block of concrete with a one-litre beer bottle (San Miguel) set into it. The glass of the bottle, being hard and smooth and rust-free, acts as the return wheel. The washers on the rope are cut from the side wall of a car tyre and each is held in place with a knot.The pipe is all basic PVC drain pipe of various sizes as detailed below.
How does it work?
The 30mm rubber washers, spaced every 70cms along the rope (5mm para-cord in this case) enters the concrete block through a 40mm pipe, goes around the bottle and then enters a 30mm pipe. This pipe is full of water up to the current water-level of the tank and the washers drag it all the way up to the top where it enters a 50mm pipe with a spout coming out of its side. Here it loses all its pressure. The water can’t go back down if the handle is still turning and it can’t go up because the 30mm washers don’t fit the 50mm tube, so it can only drop out through the spout.
To get it to run smoothly without too much friction, care has to be taken to with the size of washers and also to flare the ends of the the 3 x pipe ends where the washers enter. You do this by heating the pipe end and when it’s soft, pressing a small bottle into it. When our cistern is almost empty it’s quite hard work to wind the handle and lift water up 5m of vertical pipe, so, the main wheel at the top must provide enough friction against the rope that it doesn’t slip. The smaller and lower of the two wheels helps with this by pressing the rope against more of the larger wheel’s circumference. I’ll have a youtube video on this thing’s construction soon.