Model of Rotative steam engine, with circular metal wheel attached to wooden beam. Boiler at side; figure at front in period costume; model operates electrically
Exhibition label text:
Mr Watt’s Patent Rotative Steam Engine as constructed by Messrs Boulton and Watt, Soho, from 1787 to 1800. 10 horse power.
Low pressure steam enters the cylinder above the piston, forcing it down, As it moves down an exhaust valve opens, allowing the steam into a separate condenser. A jet of cold water is sprayed onto the steam, condensing it and causing a vacuum above the piston. this pulls the piston upwards, allowing steam to be injected into the bottom of the cylinder. Here the process is repeated in order to pull the piston down again. The piston rod runs through a gland in the sealed top of the cylinder, and attaches to the parallel motion above. James Watt was very proud of this invention, which was designed to keep the piston rod running straight and true, without the risk of it bending. At the other end of the beam, the connecting rod is attached to the Planet gearwheel. This is linked to and revolves around the sun gearwheel The gear ratio enables the flywheel to rotate at twice the speed of the engine. If the speed of the engine rises unduly, the weights on the governor will spin outwards, and in so doing, close the steam valve to slow the engine.
Other innovations to feature on this engine are a lagged cylinder for better heat insulation and a hot water and air pump for clearing the condenser and recycling the condensed steam back into the boiler.
L 104.0 W 60.0 H 55.0 cms