Reliability assessment of a grain header with a hydraulic drive of active working bodies

The reliability of grain harvesting equipment is one of the key factors affecting harvesting efficiency, crop losses, and operational costs. The aim of this study was to evaluate the reliability of a grain header equipped with a hydraulic drive of active working units and to determine the influence of the drive type on operational reliability indicators. A reliability assessment model based on a Markov state process was developed, allowing the determination of state probabilities, availability coefficient, and technical utilization coefficient for the header as a complex technical system. The model was used to identify the contribution of individual subsystems to overall reliability performance. Comparative field tests were conducted using grain headers equipped with mechanical and hydraulic drives of active working units. The obtained results showed that the drive subsystem is the limiting element of header reliability, accounting for up to 36% of failures. The application of a hydraulic drive reduced the total number of failures from 65 to 36, increased the mean subsystem MTBF from 25.21 to 193.77 engine-hours, reduced downtime more than fourfold, and increased the mean subsystem readiness factor from 0.955 to 0.995. The study confirms that hydraulic drives significantly improve the operational reliability of grain headers and can be effectively applied in the modernization and design of harvesting machinery.