Working Group on Development Techniques
Rope pump construction manual
Figure 1 shows the fundamental construction of a rope pump. A rope pump is made of a rope with attached pistons which runs through a (raising) tube. The lower side of the tube reaches the ground water and the upper side reaches above the surface. The pistons, which are attached to the rope, fit in the tube with a small tolerance (0.2…0.5mm). By pulling the rope through the tube a vacuum is created by the pistons so that water is taken up. A thin waterfilm between the piston and the tube wall takes care of the greasing and also contributes to the closing between the piston and the tube. At the upper end the rope runs over a wheel which pulls the rope through the tube. The rope runs smoothly through the tube because of a construction at the lower end of the tube.
The rope pump (made of simple materials) can be used till a depth of 40 metres. The deeper the water, the smaller the diameter of the (raising) tube. Otherwise too much weigth of water would have to be lifted. Especially for small tubes belonging to big pumpdepths it's important that the pistons are made the right size accurately.
Table 1 and 2 show which tubediameter must be used with certain pumpheights for two most used wheeldiameters.