Using delay-time analysis to study the maintenance problem of gearboxes

Uses the technique of delay-time analysis to model preventive maintenance problems of gearboxes for the Kowloon Motor Bus (KMB) Company Limited in Hong Kong. Presents a basic model of inspection maintenance, along with models of some of the variations which have been observed in the case being studied. Aims, in particular to identify the problems and requirements of KMB and then develop a delay-time model to fit the case, as well as to determine a preventive maintenance policy derived from the model so that the total maintenance cost per unit time can be minimized. Verifies the feasibility of implementing the policy according to three criteria: workers’ utilization, downtime of the gearboxes and the monthly cost incurred by both maintenance and overhead. Compares the results with those of the current policy. Suggests recommendations to KMB for improving the current maintenance policy, and highlights the general applicability of the delay-time modelling technique.