Abstract: For rapid diagnosis of the fault cause of hydraulic excavator,this article,based on the fuzzy mathematical model,presents a new fault diagnosis method.This method first gets vector of fault diagnosis by means of the combination of membership degree matrix through experience data and the expert optimal ordinal membership degree matrix,and then uses the maximum membership degree principle to get the final cause of the problem.The fault cause of hydraulic excavator SWE50 (hydraulic pump wear and lower pump oil pressure) is successfully diagnosed by this method.

Key words: hydraulic excavator, fault diagnosis, fuzzy mathematics, membership matrix