The Maudslay engine was the first beam engine built for the Kew Bridge works and began pumping in 1838.

Date of manufacture 1838
Cylinder Diameter 65 inches (1.65 metres)
Stroke 96 inches (2.4 metres)
Weight of Beam 20 tons (20.2 tonnes)
Water output per stroke 130 Gallons (590 litres)
Water output per 24 hours 2.5 M Gallons (8 M litres)
Strokes per minute 6 - 6 1/2
Last worked 1943
Returned to steam 1985

This engine was extensively rebuilt during its working life, and little of the original remains, although the original pump foundations have recently been discovered during restoration work on the Bull Engine, which is situated in the same room as the Maudslay. The engine was built by Maudslay, Sons and Field of Lambeth, who were better known as marine engineers. The engine was later converted to work on the Cornish cycle in 1848 by Samuel Homersham.

In 1888, the beam cracked and one half replaced. If you look at the beam today, you can clearly see the replacement half, which is substantially thicker than the original.