Measurement and diagnostic system for crankshaft of diesel engine

Measurement and diagnostic for crankshaft of diesel engines is very important to guarantee reliable operation through-out the working process. This paper studies on the capability of the system for crankshaft torsional oscillation. To establish the instantaneous angular speed waveform, the shaft speed signal has been used. This paper also introduced a new describing method based on the polar coordinate system of the instantaneous angular speed signal. It´s improving the discrimination features of the faults compare with the fast Fourier transform analysis. The paper studies on 8-cylinder engine by a typical experimental method and the diagnosis results by the proposed polar presentation method are given.