An improved crank-type Stirling engine. A spring, preferably a gas spring, is linked between the displacer and the housing or alternatively the power piston. The spring is relaxed at substantially a mean position of the displacer to apply a centering force upon the displacer. The spring reduces the loading...http://www.google.co.uk/patents/US4553392?utm_source=gb-gplus-sharePatent US4553392 - Self pressurizing, crank-type Stirling engine having reduced loading of displacer drive linkages
