Abstract: According to an embodiment of a hot air engine, the hot air engine includes a transmission with a connecting rod and a double-acting step piston. The double-acting step piston has a first section with a larger diameter and a second section with a smaller diameter, and is arranged in a cylinder. The double-acting step piston is at least partially hollow and the connecting rod extends through the second section and is articulatedly connected in the first section of the double-acting step piston. The double-acting step piston has sealing rings both in the first section and in the second section.

Abstract: A Stirling engine is described which, in accordance with a first exemplary embodiment, has a transmission with a connecting rod and a double-acting step piston which is arranged in a cylinder. The step piston has a first section with a greater diameter and a second section with a smaller diameter, and is at least partially hollow. The connecting rod runs on the inside through the second section, and is connected in an articulated manner in the first section of the step piston.