GEM

The GEM is a horizontal twin cylinder version of the Pevensey engine. It is typical of steam engines that powered many of the larger paddle steamboats used on the Australian inland river systems of Victoria and New South Wales.  The model derives its name from the paddle steamer "Gem", which was one of the larger paddle steamers that sailed on the Murray River.  The Gem is really no more complicated than the Pevensey to build, the extra cylinder only adds to the amount of machining not the complexity of the model. 
 

Adding Stephenson's reversing linkage the GEM becomes a horizontal marine steam engine capable of powering model paddle steamboats up to seven feet long on a boiler pressure of about up to 80 psi.  The crank throws are at 90º giving the engine self starting characteristics at any position of the crankshaft.

 6” W x 6” L  with a 3/4" Bore  x 3/4"  Stroke, and a low profile stainless steel flywheel as shown.