EASTON & ANDERSON GRASSHOPPER ENGINE

Easton & Anderson specialized in ‘grasshopper’ beam engines from 1820, named after the motion’s similarity to that of a grasshopper insect. This model was shown at the final Sandown Park exhibition and is to the excellent Anthony Mount design of an engine supplied to Winchester gas works in 1892 to drive gas exhausters that pulled coal gas from the retorts and pumped it into the gas holders. The original engine employed Meyer valve gear and a Tangye governor. Drawings and castings are available from Polly Model Engineering. Anthony’s build of the engine was described in Engineering in Miniature. It is also described in his book Historic Engines Worth Modelling Vol 2 available from TEE Publishing.

The model follows the prototype quite closely, but though it has an air pump, no condenser is fitted. Although the governor revolves it is non operational. There are two eccentrics operating a concentric rocking shaft. But there is only one slide valve fitted, the other valve rod is a dummy. The two eccentrics are fitted as the concentric shaft is such an interesting feature.

The engine is quite small with a flywheel of 5” diameter. Construction is quite straight-forward, but some parts are quite small. Castings are available for the flywheel, base, cylinder, covers, rackets, rocking frame, and beams. There are 34 drawings and a parts list, all of A4 size. The model can be built on a 3½” lathe, being quite small it might be possible to build it on some of the smaller lathes.