After how many working hours should the first-level maintenance of field vehicles be performed?

[SanJasper]

The "Refresher Training Materials for Operators of Specialized Internal Combustion Vehicles" mentions that the first-level maintenance of field vehicles should be performed after 250 working hours. Below is the relevant introduction: 1. Concept of first-level equipment maintenance: Mainly performed by operators with the assistance of maintenance workers, this maintenance is scheduled to be conducted every two months of operation (under a two-shift system) or according to plan. The maintenance duration is generally 4 to 8 hours. 2. Scope and content of first-level equipment maintenance: Based on the equipment's usage, certain components are disassembled, cleaned, and repaired. The clearance between various parts of the equipment is appropriately adjusted. Clean felt, wool, and oil filters; clear oil circuits and pipelines, replenish lubricating oil and grease, and rectify any deficiencies to ensure the equipment is free from yellow rust. All operating mechanisms, various stops, limit switches, etc., are adjusted to ensure sensitive and reliable operation. All dust-proof and chip-proof devices are cleaned and repaired to ensure they are fully functional.