Abstract:Statistical analysis of particle distribution and composition in contaminant oil within power shift steering transmission(PSST)is supposed to acquire the statistical features which can be applied for wear assessment and health evaluation.Under the theoretical balance of contamination,the contamination level of different samples was analyzed by the parameter estimation methods and solved for the distribution parameters,the balanced and the restricted values.Meanwhile,the wear stages along with operating time of PSST were assessed by the variation of distribution parameters.Besides,the composition features were analyzed by robust kernel principal component analysis(RKPCA),which was also applied for the overall and classified evaluation on health state of PSST.Through the comparison with the overhaul of PSST,both two features were verified for overall assessment on the wear stages.The research result show that the overall assessment can be combined with the classified evaluation on major parts by introducing the eigenvalues of principle components.As might be expected,the overhaul life of the PSST system can be judged accurately by the proposed method,and the maintaining suggestion of the damaged parts can be also provided.