Industrial Archaeology by Hudson Kenneth

Industrial Archaeology by Hudson Kenneth

Author:Hudson, Kenneth
Language: eng
Format: epub
ISBN: 9781317598169
Publisher: Taylor & Francis (CAM)


STEAM POWER

By 1700, the development of mining in England was seriously handicapped by flooding of the pits. The available sources of power, such as horse-gins, water-wheels and windmills, for driving baling appliances and pumps were inadequate for raising large quantities of water. The first practical engine was the atmospheric pumping engine, using steam, invented by Thomas Newcomen (1663–1729), an ironmonger of Dartmouth, in Devon, who made expeditions to Cornwall in order to sell tools to the tin-miners and had noticed the difficulties they experienced. After ten years’ experimental work, Newcomen built his first engine in 1712, at a coal-mine near Dudley Castle, in Staffordshire, and his second at Griff Colliery, near Coventry, soon afterwards.

In these engines steam was generated in the boiler at very low pressure. When the steam valve was opened, steam flowed up the pipe into the vertical cylinder. The piston-rod, carrying the piston, and the pump-rod were attached by chains to the opposite ends of a strong wooden beam, which rocked on trunnion-bearings at its centre. As the pump-rod in the mineshaft was the heavier of the two rods, it descended and pulled up the piston to the top of the cylinder. The steam valve was then closed, the injection-water valve opened and a jet of cold water condensed the steam below the piston, creating a partial vacuum in the enclosed space in the cylinder. Atmospheric pressure on the top of the piston forced it down—hence the name ‘atmospheric engine’—and this was the working stroke. The descending piston pulled up the pump-rod, which, in its turn, raised water out of the mine. When the piston approached the bottom of the cylinder, the injection-water valve was closed and the steam valve opened. The pressure was thus equalised below and above the piston, which was raised by the greater weight of the pump-rod. The mixture of condensed steam and water drained from the cylinder into a tank which supplied the boiler. As the valves were worked automatically by the engine itself, the cycle was repeated continuously.

XL. Early nineteenth century railway housing at Swindon



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