Proposed Theory of Operation.

It took a few iterations, but with the assistance of a very helpful local man, John has determined how the pump operated.

A bearing mounted low down on the pump top, opposite the spout, carries a short shaft with a hex head which originally carried a flywheel (the flywheel was removed some time ago for safekeeping and - er, was lost). The other end of this shaft carries a small crank disc.

Higher up the pump top there's another bearing, carrying a large pulley wheel. Rotation of the crank disc would result in the pulley wheel oscillating through something less than 90 degrees - at least it would do if somebody hadn't attached the conn rod to the wrong hole in the bar fixed to the pulley wheel. It should be connected to the outer hole, as otherwise it fouls the mechanism, and in fact it has now been established that it was deliberately moved so as to prevent anybody fooling around with the pump. (Still with us? Good...)

There's a short chain wrapped around the pulley wheel, and hanging from this is a metal rod, which is apparently a counterweight or chain tensioning device. It's hollow at one end and originally it would have moved up and down on a spigot which was set in the ground. And so the oscillation of the pulley wheel would have been translated into the necessary reciprocating movement and transmitted via the chain to the pump's operating rod.

Elsewhere we've found a report which states that there was a large weight in a cage in the top of the well, connected via the pulley to the pump mechanism. The report goes on to say that it was made for use in deep wells by Charles Lack of Cottenham. This might be describing yet another contraption below ground, and clearly needs further investigation.

An obscure report shows that the water table locally is very deep - "Public Well, near the church (with wheel-pump) 1885. Made and communicated by G. Ingold. All dug. Water rose to within 142 feet of the surface". (G. Ingold was a very well known pump maker and well sinker based in Bishop's Stortford, Herts.) This implies that the working barrel of the pump would have been installed at great depth and hence the operating rod must necessarily have been extremely long and therefore very heavy. Add to this the weight of the column of water being lifted and you might understand why the pump needed a fair bit of mechanical assistance.

Subsequently we've identified another pump, at Clavering, Essex, which is clearly by the same manufacturer although possibly an earlier model. This one still has its counterweight in place, which makes it easier to understand how it operated.

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