An Engineer in Wonderland – Cunning power transmission
Thinking about waterwheels the other day reminded me of a power transmission scheme that I happened across while cycling in Cornwall.
Given a waterwheel on one side of a hill, and a pump on the other, how do you power one from the other?
Now I could come up with all sorts of schemes involving pulleys and chains, hydraulic pressure, and rotating shafts in tunnels.
None of which are as simple and elegant as one at the Wheal Martyn china clay mine (pictured).
No longer in use, although the mine is still active, the power is transmitted by a series of linked horizontal rods, each running on a couple of rollers.
Connected to a crank on the waterwheel, which does still work, the rods oscillate back and forth a metre or so.
Tension from the far end – probably both ends as the rods are draped over a hill – stops the train buckling.
At the pump end, as I remember, the motion is converted to vertical by a quadrant, from where rods drop it down to pumps in the mine sump.
I suspect there are some counter weights on this bit somewhere.
The only real friction in the transmission system comes from the rollers.
There is obviously a lot of momentum to overcome in accelerating and decelerating the rod train, but the sinusoidal drive helps with this, I assume.
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