Kempton Great Engines

From 1928 until 1980 24 hours a day
both of these huge triple expansion engines pumped water to London
At 62ft high and weighing in excess of 800 tons, engine number 6 produced 1008 horse power.
It is know to be the largest engine in the World in steam today.

The two ‘Great Engines’ at Kempton Park, No's 6 and 7, are of the inverted vertical triple expansion type. The three cylinders, in which the steam is expanded in succession before passing to a condenser, are arranged in line directly over the crankshaft, with the plunger pumps below it. The layout originated though ships’ engines on a similar plan which had been used many years earlier. The Kempton examples are thought to be the biggest ever built in the UK and date from 1926-1929. Efficiency and reliability of engines of this type were hard to beat though the initial cost, including the tall engine house, was high. At one time about a third of all waterworks pumping engines in the UK were of this type though the Kempton engines were the last working survivors when they stopped in 1980. Mechanically the arrangement is attractive by virtue of the 120 degree crank setting, which not only helps to balance the moving parts but provides a steady input of power from the engine and a steady discharge of water into the pressure main. There are never less than two steam cylinders driving and one plunger pumping at any time. Each engine stands 62 ft tall from basement to top of the valve casings and weighs over 800 tons. They were supplied with steam by a battery of water-tube boilers at a pressure of 200 psi, superheated to 150°F superheat. The engines were designed for 24-hour, 7 days-a-week operation, though in practice they were run alternately. Coal consumed amounted to only about 1 and 1/4 lb per water horsepower per hour, equal to the best electricity generating stations of the day.