Letters

A better pump?

While studying the diagram of the water-lifting device (the rope-washer pump) in your last issue, I was struck by the idea of the very simple modification.

The problem is that, to work, the pump would need between 70-100cm of water. This depth of water may not always be available. If the direction of the drive is reversed and the pipe put on the bottom, instead of the top, water could be raised from a depth of only 2-3cm in a water-course.

 

Rod Mill, UK

Robert Lambert replies:

This raises a good point. I can see no reason why this would not work. However, the advantage of being able to pump from shallower water may not be so great, as the present system will allow water under 10 cm to be collected. Usually, when there is so little water left in a well, it is better to wait for the well to recharge. Another advantage with this suggestion is that the returning rope would be free of obstacles, reducing wear.

But the disadvantages would be that the pipe outlet would be lower, making collection, and particularly distribution, of the water more difficult. If, to compensate for this, the pump axle is raised, it would be more difficult to turn the handle, unless a platform (which women might be unwilling to mount) was used.

I will suggest the idea to pump-makers and trainers. We will see how they respond.

Robert A Lambert

The diagram of the pump in Issue No. 7 included a complicated support in the water. In fact, a simple support of bent wire with a glass bottle acting as a non-rotating pulley is quite effective.