Two Cylinder Stirling Engine

This resource provides an animation and diagrams of a Stirling Engine that illustrates expansion, transfer, and contraction. The Stirling engine is a very simple engine, and was often billed as a safe alternative to steam, since there's no risk of a boiler explosion. Stirling engines feature a completely closed system in which the working gas (usually air but sometimes helium or hydrogen) is alternately heated and cooled by shifting the gas to different temperature locations within the system.