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Whitbread Engine – Watt Rotative Beam

Boulton & Watt steam engine, Sydney Powerhouse Museum

Whitbread Engine

This Whitbread Engine was built in 1785 and is one of the first rotative steam engines ever built, and is the oldest surviving. This engine was designed by James Watt and was manufactured by Boulton and Watt and was initially installed in the Whitbread brewery in London, England. On decommissioning in 1887, it was sent to Australia to be exhibited in an early Technological Museum and has since been restored to full working order.

A rotative engine is a type of beam engine where the reciprocating motion of the beam is converted to rotary motion, producing a continuous power source suitable for driving machinery. The engine is notable for its age the pioneering of four innovations which made Boulton & Watt’s engines a significant accelerator of the Industrial Revolution:

  • A separate condenser, which increases the efficiency of the engine by allowing the central cylinder to remain hot at all times.
  • The parallel motion, which converts the up-and-down movement of the piston into the arcing motion of the beam. The rigid connection allowed the engine to be double-acting, meaning the piston could push as well as pull the beam.
  • The centrifugal governor used to automatically regulate the speed of the engine.
  • The sun and planet gear convert the reciprocating motion of the beam into a rotating movement, which was used to drive rotating machinery.

Sun and planet gearsSun and planet gear mechanism that translates vertical motion to rotary motion.

The engine was ordered in 1784 to replace a horse wheel enabling Whitbread to become the largest brewer in Britain. Connected machinery included rollers to crush malt; an Archimedes’ screw, that lifted the crushed malt into a hopper; a hoist, for lifting items into the building; a three-piston pump, for pumping beer; and a stirrer within a vat. This engine remained in service for 102 years, until 1887.

Boulton & Watt steam engine, Sydney Powerhouse Museum

Whitbread Engine – Watt Rotative Beam

  • Title:              Whitbread Engine
  • Date:              1785
  • Type:              Watt, Rotative Beam
  • Designer:      James Watt
  • Maker:           Boulton and Watt
  • Country:        England
  • Use:                Driving brewery machinery
  • Museum:      Powerhouse Museum

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We are just passing through. Our purpose here is to observe,
to learn, to grow, to love… and then we return home.”

– Australian Aboriginal saying


Photo Credit: By David Maciulaitis from Auckland, New Zealand (DSC01691) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons 2) By No machine-readable author provided. Emoscopes assumed (based on copyright claims). [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or CC BY 2.5 (http://creativecommons.org/licenses/by/2.5)], via Wikimedia Commons 3) By David Maciulaitis from Auckland, New Zealand (DSC01694) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons