Sherwood Colliery - steam winding engine

Image: © Chris Allen Taken: 25 Mar 1981

This was the smaller of the two winding engines and was a horizontal duplex built in 1902 by Fraser & Chalmers of Erith. The Corliss valve cylinders were 26 x 54" and fitted with Seymour's patent valve gear (the only example I ever saw) under governor control. The parallel drum was 11' diameter. The engine was scrapped in 1983 but one cylinder was taken to the National Mining Museum at Lound Hall. This museum is long since closed and the fate of the cylinder is not known. The colliery was demolished many years ago. This view shows a close-up of the Corliss valves with Seymour's gear. The steam (inlet) valves are in the top corners with variable cut-off under governor control and the exhaust valves are out of sight in the bottom corners. The vertical rod on the extreme right is oscillated by a separate eccentric and carries a cam at the top. The timing of this cam is varied by the governor. The cam bears on a pin that passes through the carrier oscillated by the wristplate (bottom centre) and pushes apart the trip dies to release the valve to be closed by a spring and dashpot assembly. The pin that pushes the dies apart is barely visible (I can see it, just). All this complexity is to allow for a later cut-off than is possible with more conventional Corliss gears and allows the engine to develop maximum power (up to 95% cut-off) while accelerating the cages and then let the governor shorten the cut-off and reduce the power during the constant speed phase of the wind.

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