Tom blok Photo collection by Th.Schiöler Spiral scoops, screws and the chain pump Tread-wheels Photo 156
Tread-wheels
Gul streg
Photo 511 x 506 pixels, 43,6 K
 
The Chinese tread-wheel or dragon's backbone wheel
Among all kinds of man powered water-lifting devices, this is the best one. The three men's tread are staggered at 120 degrees from each other, resulting in the shaft running at a constant speed.
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