At Crossness, the incoming liquid was raised some 30-40 feet by the application of four large steam driven pumps. The engines were of enormous size and power. They were built by James Watt & Co. to Joseph Bazalgette's designs and specification, and were named "Victoria", "Prince Consort", "Albert Edward" (the Prince of Wales) and "Alexandra" (the Princess of Wales). As originally built, they were single cylinder rotative beam engines - that is, with a flywheel - the piston being of 9'0" stroke and of 4'0" diameter, developing 125 horse power. The valve gear (admitting live steam and expelling exhaust) was situated below the working floor and was operated by a camshaft driven from a bevel gear on the flywheel axle. The flywheel provided was 27'0" in diameter, weighing 52 tons. The rocking beam was 43'0" in length, and on each side of the central pivot, a cruciform pump rod was pivotted, and connected to four 4'6" plungers working inside a 12'0" diameter barrel. At 11 revolutions per minute, 6 tons of sewage per stroke per engine were pumped up into the reservoir. The steam required to power these engines was raised by 12 Cornish boilers with single "straight-through" flues situated in the Boiler House to the south of the Engine House,and which consumed 5,000 tons of Welsh coal annually. The Crossness Works merely disposed of raw sewage into the river seawards,and in 1882, a Royal Commission recommended that the solid matter in the sewage should be separated out, and that only the liquid portion remaining should be allowed, as a temporary measure, to pass into the river. In 1891, sedimentation tanks were added to the works,and the sludge was carried by steam boats and dumped further out into the estuary, at sea. By 1897, additional pumping capacity was needed, and four extra pumps operated by triple-expansion steam engines were installed in an extension, designed to fit in with Bazalgette's main engine house, to the north of the older building. Later,in 1899, a further increase in London's population necessitated an increase in the efficiency of the original Watt engines, and considerable alteration to their design was carried out by Goodfellow and Co of Hyde, Manchester, for the LCC. They were converted from simple to compound engines - that is,the original single cylinders were augmented by high and intermediate pressure cylinders, whereby steam admitted to the HP cylinder was exhausted into a larger IP cylinder and then into the original cylinder at low pressure. From there the steam exhausted into condensers which not only economised in water supply,but assisted in power by creating a partial vacuum behind the sequence of cylinders. The additional steam required was provided by replacing the earlier Cornish boilers by more efficient Lancashire boilers with double flues.
Additional parallel motion links were provided to deal with the extra connecting rods,and massive counterweights were added to the outer ends of the main beams. Steam operated barring engines - used to get the main engines into the correct starting position - were fitted to drive the toothed flywheels to start the now very much heavier main engines. Finally, the four 4'6" pump plungers in each barrel were replaced by one 9'0" diameter plunger, and in 1901 the improved engines were fully working.
In 1913, the triple expansion steam engines were replaced by diesel engines, which are still to be seen in the triple expansion engine house, and by 1956, the Watt-Goodfellow engines had been decommissioned, (Prince Consort having been temporarily put back in steam in 1953 to assist with draining the flooding of the eastern Royal Arsenal and Abbey Wood) and were left, with the rest of the ironwork, to rust and to vandals