Abstract
In the Army of the Czech Republic, a large number of heavy military vehicles was observed in service over a long time period to collect data on their reliability and maintainability, including relevant economic data. The data obtained were used for determination of basic dependability characteristics of the vehicle and its main sub-systems and for analysis of the vehicles LCC. Among other findings, the results of this analysis showed an unsatisfactory level of the costs associated with maintaining the vehicle. For this reason, it was decided to look for ways to reduce maintenance costs through a change of the maintenance concept of the vehicle.
The solution was limited by the requirement not to change the basic principles of the maintenance concept, which are determined by the general maintenance police of the army. It meant that the improvement desired could be achieved only through a change in the frequency of preventive maintenance. The original maintenance concept of the vehicle included also, besides classical preventive maintenance actions, scheduled repairs with the aim to replace or repair the stated vehicles sub-systems and parts whose life cycle is shorter than the expected vehicle life cycle as such. The accomplishment of these scheduled repairs is very expensive and represents a decisive part of preventive maintenance costs of the vehicle. For these reasons, it was decided to analyse especially the influence of these repairs frequency on the amount of maintenance costs.
As a solution to the above-mentioned tasks, the articles authors created a mathematical model describing relationships between the overall LCC of the vehicle and frequency of the prescribed maintenance actions. This model allows us to determine the frequency of repairs in which LCC of the vehicle reaches the minimal level.
This article describes in detail an applied mathematical model and it also analyses the possibilities and conditions of its practical use for optimisation of the conception of vehicle maintenance. Practical application of the proposed method is demonstrated on an example of optimisation of period of replacement of the subsystem of the vehicle drive train that is performed as a part of its preventive maintenance.
The method presented was actually used for the maintenance concept optimisation in the case of the above-mentioned military vehicle. This application showed that the method could be used as a simple and very useful tool for the improvement of the maintenance concept and reducing the LCC. The article presents the most interesting results of monitoring the vehicle in service, as well as the results of the maintenance optimisation.
The successful application of the method asserts that the reasonable use of operating data and their analysis can contribute to reducing the number of preventive maintenance actions and, consequently, to decreasing maintenance costs. The method presented is a good example of practical usage of operating experience for improving the maintenance concept.