Object StatementSteam engine, six-column beam type, cast iron / steel / brass / paint, made by Maudslay, Sons & Field, Engineers, Lambeth, London, England, 1837, used at William Bradley's flour mill and brewery, Goulburn, NSW, Australia, c1837-1921
Physical DescriptionThis rotative double acting six-column beam engine is capable of developing 12 horsepower (8.9 kW) at 20 rpm when supplied with steam at a pressure of 7 psi (48 kPa). It is similar to the museum's Boulton & Watt beam engine except that it is free-standing, the cooling water tank runs the whole length of the engine, and the flywheel is turned by a crank. It features classical columns, a corniced entablature, and a panelled plinth around the tank. Most parts of the engine are painted green. The cylinder, which is cast in one piece with its steam jacket, is painted black.
There are five vertical rods hanging from the overhead beam. Viewed from the front (that is, with the flywheel at the back), the rod on the far right is the piston rod. Pushed by steam acting on the piston in the cylinder below, the piston moves the beam via a Watt parallel motion mechanism, which converts the straight-line motion of the rod into the arc-wise motion of the end of the beam.
The second rod (to the left of the piston rod) operates the air pump, which sits in the tank below the cylinder and which evacuates the separate condenser and delivers the condensate (water formed when the exhaust steam cools) to a small holding tank. The third and fourth rods operate pumps that return the condensate to the boiler through the black-painted pipes.
The heavy cruciform rod at the left hand end of the beam is the connecting rod, which drives the output shaft and flywheel through a crank. The flywheel maintains momentum throughout the engine's stroke. It is cast in two parts, which are elegantly joined via curved scarf joints at the rim and hub. Its eight spokes are octagonal in cross section and splay smoothly to meet the hub and rim.
Steam supply to, and exhaust from, the top and bottom of the cylinder is controlled by the valve gear attached to the right hand side of the cylinder. Steam is supplied cyclically above and below the piston by a sleeve valve driven, via a bell-crank lever, by a long triangular linkage connected to an eccentric on the crankshaft. A second, concentric, sleeve valve regulates the duration of steam admission and thus controls the speed of the engine. This control is achieved by the use of the Watt governor (on top of the engine at the far left-hand side) acting through two bell-crank levers and a rod running the length of the engine. The governor is driven by a belt drive from the crankshaft through a pair of bevel gears.
Cylinder bore: 22 inches (559 mm),
Cylinder stroke: 30 inches (762 mm).
Speed: 20 to 30 revolutions per minute
Valve: Very rare long "D" type (virtually as long as the cylinder)
Valve gear: Eccentric and gab
Governor: Centrifugal Watt type
MarksPlaque on side with raised lettering "MAUDSLAY / SONS & FIELD / ENGINEERS / LONDON / 1837"