As a commonly used construction machinery in engineering construction, the maintenance work of loaders directly affects the service life, operation efficiency and safety of the equipment. The following details the maintenance knowledge of loaders from the aspects of daily maintenance, regular inspection, common fault handling and maintenance precautions:
I. Daily Maintenance (Before and After Daily Operations)
Daily maintenance is the foundation for preventing faults and should be carried out before and after each operation, focusing on the following contents:
- Appearance and Basic Inspection
- Wheel loaders: Check whether the tire pressure is normal, whether the tire tread has cracks, bulges or embedded foreign objects, and whether the wheel hub bolts are loose.
- Track loaders: Check the track tension (pressing the middle of the track by hand, a sinking amount of about 20-30mm is appropriate), whether the track plates and bushings are worn or broken, and whether the track frame bolts are tight.
- Engine oil: Check the oil level with the dipstick to ensure it is between "MIN" and "MAX". At the same time, observe the color of the oil (normally light yellow or brown; if it turns black, it needs to be replaced in time).
- Coolant: Check the liquid level in the expansion tank. If it is insufficient, add the same type of coolant (avoid adding tap water to prevent scale).
- Hydraulic oil: Check the oil level gauge of the hydraulic oil tank to ensure it is within the specified range. Pay attention to whether the hydraulic oil is emulsified or contains impurities (emulsification may be due to water ingress, so the seal needs to be checked).
- Fuel: Check the fuel quantity and regularly drain water and sediments from the bottom of the fuel tank (especially in humid environments).
- Cleaning: Remove soil, gravel and other debris from the machine body, tires (or tracks) to avoid component wear; clean the surface of radiators and air filters to prevent poor heat dissipation.
- Liquid Level Inspection:
- Tires / Tracks:
- Functional Inspection of Key Components
- Engine: After starting, listen to the running sound (it should be smooth without abnormal noise) and observe the exhaust color (normally colorless or light gray; black smoke may be due to insufficient combustion, and blue smoke may indicate oil burning).
- Hydraulic system: Operate the boom, bucket and other movements to check whether they are smooth, with no jamming or slowness; observe whether the hydraulic pipelines and joints are leaking (leakage will cause pressure drop, and the seals need to be replaced in time).
- Brake system: Test the service brake and parking brake to ensure they are sensitive and reliable; check the brake fluid level and the wear of the brake shoes (if worn excessively, they need to be replaced).
- Lighting and instruments: Check whether the headlights, turn signals and warning lights are normal, and whether the instrument panel display is clear (such as whether the water temperature, oil pressure, power and other indicators are within the normal range).
II. Regular Inspection and Maintenance (By Operating Hours or Cycles)
According to the operation intensity of the loader and the instruction manual, formulate a regular maintenance plan (usually with cycles of 50, 200, 500, and 1000 hours), focusing on the following:
- 50-200 Hours Maintenance
- Replace filters: Replace the engine oil filter and diesel filter (to prevent impurities from entering the engine); clean or replace the air filter (especially in dusty environments, the cycle needs to be shortened).
- Lubrication maintenance: Add grease to each hinge point (such as the connecting pins between the boom and the frame, and between the bucket and the boom) to ensure sufficient lubrication of moving parts and reduce wear.
- Check belts and chains: Check the tightness of engine belts (such as fan belts and generator belts) (pressing the middle of the belt, a deflection of about 10-15mm is appropriate). If there are cracks or wear, replace them; check the tension and lubrication of the drive chain (for some models).
- 500-1000 Hours Maintenance
- Engine: Check the valve clearance, the working status of the fuel injector, and clean up carbon deposits.
- Hydraulic system: Check the operation status of the hydraulic pump and hydraulic motor, and measure whether the system pressure meets the standard (such as the boom lifting pressure is about 16-20MPa, which varies by model).
- Structural parts: Check whether the welded parts of the frame, boom, bucket, etc., have cracks (especially after long-term heavy-duty operations). If there are, they need to be repaired and reinforced by welding in time.
- Engine oil: Replace according to the model specified in the manual (such as 15W-40) and clean the oil pan at the same time.
- Hydraulic oil: Replace the hydraulic oil and hydraulic oil filter. Before replacement, drain the old oil and clean the hydraulic oil tank to avoid mixing and contamination of new and old oils.
- Gear oil: Replace the gear oil in the front and rear axles and the gearbox, and check whether the gearbox is leaking.
- Replace oils:
- In-depth inspection of components:
- Maintenance for Long-term Storage (Not Used for More Than 1 Month)
- Clean the machine body, park it in a dry and ventilated place, and pad up the tires to avoid pressure deformation.
- Drain all fuel and coolant (antifreeze is needed in cold areas). Let the engine idle for a few minutes before stopping to prevent residual oil from corroding components.
- Remove the battery, store it separately after being fully charged, and replenish the power regularly.
- Apply anti-rust oil to exposed metal parts and add grease to moving parts.
III. Common Faults and Handling Methods
| Fault Phenomenon | Possible Causes | Handling Methods |
|---|---|---|
| Difficult engine start-up | 1. Insufficient fuel or blocked fuel line 2. Insufficient battery power or loose wiring 3. Faulty spark plug (for gasoline engines) or fuel injector (for diesel engines) | 1. Check fuel quantity, unblock the fuel line, and replace the diesel filter 2. Charge or replace the battery, and tighten the wiring 3. Clean or replace the spark plug / fuel injector |
| Slow movement of the hydraulic system | 1. Insufficient hydraulic oil or contaminated oil quality 2. Worn hydraulic pump with insufficient pressure 3. Faulty relief valve | 1. Replenish or replace hydraulic oil and clean the filter 2. Overhaul or replace the hydraulic pump 3. Debug or replace the relief valve |
| Brake failure | 1. Insufficient brake fluid or leakage 2. Excessively worn brake shoes 3. Air in the brake pipeline | 1. Replenish brake fluid and repair the leakage point 2. Replace the brake shoes 3. Bleed air from the brake pipeline |
| Abnormal tire wear | 1. Excessively high or low tire pressure 2. Incorrect wheel hub alignment 3. Uneven load | 1. Adjust to standard tire pressure 2. Correct the wheel hub alignment 3. Avoid unbalanced loading |
IV. Maintenance Precautions
- Safety first: Before maintenance, stop the machine, pull the handbrake, pull out the key, place a support under the boom (to prevent accidental falling), and avoid maintenance operations on slopes.
- Use original accessories: Give priority to original or standard-compliant accessories for filters, oils, seals, etc., to avoid equipment damage caused by inferior products.
- Record maintenance files: Record in detail the time, content, replaced parts and other information of each maintenance to facilitate tracking the equipment status and timely detection of potential problems.
- Operation by professionals: Complex repairs (such as engine disassembly and hydraulic pump overhaul) should be carried out by professional technicians to avoid secondary faults caused by improper operation.
Through scientific and standardized maintenance, the service life of the loader can be significantly extended, the failure rate can be reduced, and the operation efficiency and safety can be guaranteed. In actual operation, the maintenance plan should be flexibly adjusted in combination with the equipment model and instruction manual.
