The heat-creating burner (28) has a a heater (23) and a combustion chamber (30). It runs on a flame-free oxidation basis, so that the creation of thermal nitrogen oxides is suppressed. By this means, the content of such oxides in the exhaust gas is reduced...

The piston and cylinder unit includes a piston with at least one piston ring groove (35). The spacing between the piston ring groove closest to the crankshaft and the bottom edge (43) of the piston body (41) is between 0.66 and 1.5 times the piston stroke,...