Study on reliability modelling of a hydraulic excavator system

The failure patterns of a well-known brand of a hydraulic excavator system used in different environments were modelled adequately with an NHPP (non-homogeneous Poisson process) having time-dependent log-linear peril rate functions. Using the fitted model, the reliability of the excavator system was estimated in different environments (cement plant, coal mine, iron ore mine, etc.). The system reliability was found to be very poor during the initial phase of operation and gradually improved with an increase in cumulative operating hours regardless of change in environment. Notwithstanding this general trend, the system reliability differed significantly in different environments for any given duration of operation and was particularly very poor in cement plants. With the help of the FMEA (failure mode ans effect analysis) technique, high risk prone failure modes of the excavator system of the given model were identified and appropriate corrective measures were initiated. The failure patterns of the modified excavator system changed regardless of environment, so much so that an HPP (homogeneous Poisson process) model with constant peril rate could be fitted adequately to characterize the failure pattern of the system. The system reliability improved considerably in the initial phase of operation since start-up