Moreover, when such vehicles will be resold, them they are fit in three groups of operation, being able to be the severe one, the road and the mixing. The Severe one is when the vehicles are used in extreme conditions, operating in the maximum load limit, that is the case of the national company Gas Butane. Already the road, if fits when the vehicles pass through roads or highways paved in good condition. The mixing are when the vehicles are used in combinations ' ' Bitrem' ' with gross weight total maximum limited in 57 tons. In accordance with Ferber (2010), supervisor of Engineering of Service & Training of Mercedes-Benz, in function of these classifications the road with bigger stated periods and minors are defined the periods between the maintenances being requests. The severe service that is the used one for the company in study is what it presents minors stated periods between the maintenances. According to Pinto and Xavier (2001), the preventive maintenance is applied in order to reduce or to prevent the imperfection or fall in the performance; it counts on a plan of action, based on definite intervals of time. Moreover, it is responsible for defect zero, preventing and keeping the control on all the process.

As the authors, the cost of the preventive maintenance is raised, a time that the equipment can be substituted before finishing its useful life. To implant the preventive maintenance, the organization must consider some factors: complex impossibility of the adoption of preditiva maintenance, risks of aggression to the environment, systems or of continuous operation, among others. 3,2 COST OF MAINTENANCE For Leone (1997), costs are the values of the factors of production consumed by a company to develop its products or services. Being thus, the productive process started to demand new values to the substance cousin, a time that the services and products had passed to add, beyond the cost of the substance cousin and the used materials, the hand of workmanship, the rent of the place where the products are manufactured, and mainly the quality of the service or product.