Coleham Pumping Station was built inside-out. W.R. Renshaw, of Stoke, built on site two steam-driven Woolf beam engines in 1897/8, to pump Shrewsbury's sewerage. The building was then erected around the engines in 1900, and opened a year later.
The rotative beam engines are compound, with side-by-side high pressure (13 inch bore) and low pressure (20 inch bore) cylinders, together producing about 25 horsepower. The piston rods connect to the beam by means of James Watt's parallelogram coupling, enabling the up-and-down movement to be connected to a beam that moves in a slight arc.
With the pistons moving in a straight line, they can be driven from both above and below. Watt's double-acting cylinders saved greatly on coal, and he took a share of the saving on an ongoing basis. Fitted to the side of the cylinders is Watt's device for measuring the efficiency of his engines, his means for checking the amount due for energy not used.
The engines drive flywheels of about 16 feet diameter and 10 tons weight, the inertia of which then drive the pumps, able to move about 1,200,000 gallons per day, exceedingly smoothly. A two-pence piece will balance on its side upon the moving beam without falling over.
Two Cornish boilers by W&J Galloway, of Manchester, 21 feet long and five-and-a-half feet wide, provide the steam. The fire sits at the front of the furnace tube, through which pass the fire's hot gases. The tube runs to the back of the boiler, then under it, and finally along its sides, such that the water is heated from both within and without.
The coil-fired boilers and beam engines drove the pumps until 1970, when submersible electric pumps were installed in the sewerage pipes. It wasn't until 2003 that the pumping station was disconnected from the town's sewerage system. The Shrewsbury Steam Trust has restored the boilers, engines and pumps to the highest of standards.