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What's new: Sat Oct 18 (2003) Roller development
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Roller development

Prototypes: strips, rings, disks

The test rig of the rope pump has many new components. In fact only the electric engine, its drive disk and the big two meter diameter wheel, that it drives remain from the first setup. As the big wheel is not round at all (it has 12 corners), it needs a roller to keep the tension on the rope steady, specially the unloaded part, moving back to the electric engine.
In the old setup a sort of lightweight pulley folded from thin aluminum sheet did the tensioning. This worked fine, but the pulley was to difficult to make.

How the strips fit into the disks

Together with Bram de Vries I tried to simplify the making of this tensioning roller. We started out with a cylinder of bamboo slats, woven into a strip (left in picture). We found this too heavy and side ways flexible. For the bearings we had a woven construction in mind. Sideways stability was achieved with less bamboo by tying it zigzag on two rings wound from wire. Stability was perfect, but the woven bearing was difficult to make. (middle position, woven bearing removed).
Amazingly easy it proved to be to insert the bamboo sticks in a zigzag way into disks cut from a bucket. Six small square holes and an shallow slot in the bamboos did the trick. The lower picture shows this detail
Puncturing the disk in the middle with a piece of wire results in the creating of the bearing as well as of the axle.


What's new: Roller development
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