Water lifted from the wells was deposited into a 26,000 gallon impound chamber, situated beneath the engine house floor and from there was pumped by the ram pumps to the Hanchurch reservoir 4 miles away. These pumps, and their attendant equipment, tower up at the far end of the engine house.
Each assembly consists of a double acting ram pump. The two cylinders of the pump, of 16-inch internal diameter, are positioned end to end and share a common ram, which is mounted on the piston rod extension.
Three air vessels are fitted to the ram pumps. The first of these vessels is situated on the floor of the engine house connected to the suction pipe from the impound chamber. The second is fitted at the outlet junction of the pipes from the ram pump and the third can be seen adjacent to the steps leading from the engine house.
These air vessels have two functions. The first is to help maintain a more or less uniform rate of water flow from the ram pumps. When the pump is discharging water at its minimum pressure the level of water in the air vessel will be low. As the rams velocity increases so does the discharge pressure from the pump and the air in the air vessel is compressed, thus causing the water level to rise and a volume of water to be stored in the vessel. When the rams velocity drops so does the pumps outlet pressure and the water in the air vessel is forced out by the compressed air into the main. It is this action that helps maintain a uniform rate of water flow. The second function of the air vessels is to absorb the shock produced by the column of water when the pump stops.
Compressed air for these vessels was originally supplied by a Westinghouse steam powered compressor, pictured left, which is located on the engine house wall behind the left hand engine, and latterly by internal combustion engine driven compressor sets.