This paper focuses on a problem of vibration-based condition monitoring and fault diagnosis of pumps used in the tractor steering system. The vibration-based machine condition monitoring and fault diagnosis incorporate a number of machinery fault detection and diagnostic techniques. The vibration signal from a piezoelectric transducer was captured for the following conditions: Normal pump (GOOD), Journal-bearing with inner face wear (BIFW), gear with tooth face wear (GTFW), and Journal-bearing with inner face wear plus gear with tooth face wear (G&BW) for three working levels of pump speed (1000, 1500, and 2000 rpm). Then Power Spectral Density (PSD) of vibration spectra was calculated. According to the results, fault diagnosis of hydraulic pump is a difficult task using spectrum of vibration signals alone. Results showed that different faults were showed different PSD versus frequency diagram. Comparison of numerical data produced by calculation the area under PSD v. Frequency diagram show that energy technique is an effective method for fault diagnosis of external gear hydraulic pumps.
