Engine Overhaul Indicators
A major overhaul should be considered when the engine exhibits any of the following conditions:
1. Significantly reduced power performance: Even after adjustments, the engine remains weak, requiring load reduction (e.g., downshifting a tractor or reducing the rated load of machinery by more than 15%), and fuel consumption increases, with unstable idling.
2. Excessive cylinder wear: The cylinder wall's out-of-roundness or taper exceeds the usage limit, causing the compression force of each cylinder to be lower than 60% of the standard pressure when the engine is warm.
3. Abnormal oil consumption: Without external leakage, the oil level exceeds the quota by 100% (e.g., every 1000 kilometers for a car or every 100 hours for machinery), and the crankcase is smoking, with oil pressure below the minimum limit.
4. Severe abnormal noise: Continuous knocking during operation, or knocking noise from bearings, piston pins, etc.
Major Overhaul Indicators for Electric Motors
Major overhaul of electric motors includes:
1. Coil temperature exceeding rated temperature rise under rated load;
2. Coil burnout, open circuit, short circuit, or substandard insulation resistance;
3. Bent, loose, or cracked rotor shaft, or burnt-out or worn-to-limit slip rings/commutator.
Major Overhaul Indicators for Generator Sets
Major overhaul conditions for both the prime mover (internal combustion engine/electric motor) and the generator assembly must be met simultaneously.
Systematic Maintenance and Fault Prediction
Regular maintenance can detect potential problems in advance, avoiding sudden major overhauls:
1. Routine Maintenance: Clean the vehicle body, check fluid levels (fuel, hydraulic oil, coolant, etc.), and monitor battery and tire condition.
2. Regular Inspections: Check track tension every 50 hours, change engine oil and filter every 500 hours, and clean the radiator regularly. 3. Fault Warning: If problems such as difficulty starting, insufficient hydraulic pressure, or abnormal vibration occur, timely troubleshooting is necessary (e.g., replacing the battery, repairing the oil pump, adjusting vibrating components) to prevent minor issues from accumulating into major overhauls.
Special Provisions for the Break-in Period: New machines or machines after major overhauls must adhere to the break-in period regulations (usually 100 hours). Reduce the load to 80% of the rated load, limit the speed to 30%, and strengthen maintenance (e.g., cleaning the lubrication system, tightening components) to extend the overhaul interval.
