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Water Balance Headgear, at Big Pit, Blaenavon, 2002.
The Water Balance winding method.
A heavy cast iron and wooden frame erected over the shaft supported a large grooved wheel to facilitate the movement of the winding chain, each end of which a cage was attached, at the bottom of each cage was a water tank which could be quickly emptied and refilled.
The tank was filled at the surface until its weight was sufficient to raise the cage from the bottom, which had been emptied of water and loaded with coal or men. The braking system was controlled by a lever, which applied pressure to a flywheel.
As described by a mining engineer at Cwm Bargoed pit 1862.
The water-balance pit, used where there was an abundant supply of water, was peculiar to South Wales. An example of it, used at the Cwm Bargoed pit of the Dowlais Iron Company, where 300 tons of coal were raised up a shaft 154 yards deep from the Upper Four Feet seam in a twelvehour day, was described by the mines inspector for South Wales Thomas Evans.
The tram containing about 20 cwt. of coal is placed on the top of an empty water bucket at the shaft bottom; and the empty tram on the bucket at the top; this bucket upon being filled with water descends, raising the full tram of coal and the empty bucket from the bottom. A valve is placed at the bottom of each bucket, and, immediately on its arrival at the shaft bottom, the valve is lifted and the water let off.
Beneath each bucket was a chain to aid the balance. The speed
of working depended on the rate at which the bucket could be
filled with water: at Cwm Bargoed the buckets held about 2 tons
of water and each complete winding operation took about 1 minute
20 seconds. The water might, as at Cwm Bargoed, be pumped to the
surface to be used again, or might, where there was free
drainage, be allowed to flow away, possibly to another balance
machine.
In 1862, in Glamorgan alone, there were about sixty of these
machines at work, all the pits of the great Cyfarthfa works being
operated on this basis.