In a method for indirectly ascertaining the cylinder pressure during the operation of piston engines by measuring cylinder pressure-dependent parameters at crankshaft bearings of the piston engine, one essential feature is that the force which is introduced by the main bearings of the crankshaft into an engine housing is measured. For performing the method, sensors for obtaining cylinder pressure-correlating signals are disposed on the bearing screws, and that the signals generated by the sensors are carried to the outside.