Abstract
This article describes the method of mathematical statistics for studying the wear of parts of modern machines. It is examined how the service life of the parts is established. It was also assumed that the statistical data on the size of worn parts obey the law of normal distribution. The figure presented in the paper illustrates the scheme for determining the inter-repair service life of the part for this case according to statistical data. An example is considered that allows to establish the norm of the maintenance period of the support roller of a modern tractor VT-150. This article is recommended for agricultural specialists, researchers, teachers, postgraduates, undergraduates and students of agricultural universities in the field of training “Agroengineering”.