In the manufacturing process of the tracked undercarriage chassis for construction machinery, the running test that needs to be conducted on the entire chassis and the four wheels (usually referring to the sprocket, front idler, track roller, top roller) after assembly is a crucial step to ensure the reliability and durability of the chassis. The following are the key points to focus on during the running test:
I. Preparations before the test
1. Component cleaning and lubrication
- Thoroughly remove assembly residues (such as metal debris and oil stains) to prevent impurities from entering the device and causing abnormal wear due to friction.
- Add special lubricating grease (such as high-temperature lithium-based grease) or lubricating oil as per technical specifications to ensure that moving parts such as bearings and gears are adequately lubricated.
2. Installation Accuracy Verification
- Check the assembly tolerances of the four wheels (such as coaxiality and parallelism), ensuring that the drive wheel engages with the track without deviation and that the tension of the guide wheel meets the design value.
- Use a laser alignment tool or dial indicator to detect the uniformity of contact between the idler wheels and the track links.
3. Function Pre-inspection
- After assembling the gear train, manually rotate it first to ensure there is no jamming or abnormal noise.
- Check if the sealing parts (such as O-rings and oil seals) are in place to prevent oil leakage during running-in.
II. Key Control Points During Testing
1. Load and Operating Condition Simulation
- Staged Loading: Start with a low load (20%-30% of rated load) at a low speed in the initial stage, gradually increasing to full load and overload (110%-120%) conditions to simulate the impact loads encountered in actual operations.
- Complex Terrain Simulation: Set up scenarios such as bumps, inclines, and side slopes on the test bench to verify the stability of the wheel system under dynamic stress.
2. Real-time Monitoring Parameters
- Temperature Monitoring: Infrared thermometers monitor the temperature rise of bearings and gearboxes. Abnormally high temperatures may indicate insufficient lubrication or friction interference.
- Vibration and Noise Analysis: Acceleration sensors collect vibration spectra. High-frequency noise may point to poor gear meshing or bearing damage.
- Track Tension Adjustment: Dynamically monitor the hydraulic tensioning system of the guide wheel to prevent the track from being too loose (slipping) or too tight (increasing wear) during running-in.
- Abnormal Sounds and Changes: Observe the rotation of the four wheels and the tension of the track from multiple angles during running-in. Check for any abnormal changes or sounds to accurately and promptly locate the position or cause of the problem.
3. Lubrication Condition Management
- During the operation of the chassis, check the grease replenishment in a timely manner to prevent the deterioration of the grease due to high temperatures; for open gear transmission, observe the oil film coverage on the gear surfaces.
III. Inspection and Evaluation after Testing
1. Wear Trace Analysis
- Disassemble and inspect the friction pairs (such as the idler wheel bushing, drive wheel tooth surface), and observe whether the wear is uniform.
- Abnormal wear type determination:
- Pitting: poor lubrication or insufficient material hardness;
- Spalling: overload or heat treatment defect;
- Scratch: impurities intrude or seal failure.
2. Sealing Performance Verification
- Conduct pressure tests to check for oil seal leakage, and simulate a muddy water environment to test the dust-proof effect, to prevent sand and mud from entering and causing bearing failure during subsequent use.
3. Re-measurement of Key Dimensions
- Measure the key dimensions such as the diameter of the wheel axle and the meshing clearance of the gears to confirm that they have not exceeded the tolerance range after running.
IV. Special Environmental Adaptability Testing
1. Extreme Temperature Testing
- Verify the anti-loss ability of the grease in high-temperature environments (+50℃ and above); test the brittleness of materials and cold start performance in low-temperature environments (-30℃ and below).
2. Corrosion Resistance and Wear Resistance
- Salt spray tests simulate coastal or deicing agent environments to check the anti-corrosion ability of coatings or plating layers;
- Dust tests verify the protective effect of seals against abrasive wear.
V. Safety and Efficiency Optimization
1. Safety Protection Measures
- The test bench is equipped with emergency braking and barriers to prevent unexpected accidents such as broken shafts and broken teeth during running-in.
- Operators must wear protective gear and keep away from high-speed rotating parts.
2. Data-driven Optimization
- By establishing a correlation model between running-in parameters and lifespan through sensor data (such as torque, rotational speed, and temperature), the running-in time and load curve can be optimized to enhance testing efficiency.
VI. Industry Standards and Compliance
- Adhere to standards such as ISO 6014 (Test Methods for Earth-moving Machinery) and GB/T 25695 (Technical Conditions for Track-type Construction Machinery Chassis);
- For export equipment, comply with regional certification requirements such as CE and ANSI.
Summary
The four-roller running test of the crawler undercarriage chassis should be closely combined with the actual working conditions of construction machinery. Through scientific load simulation, precise data monitoring and strict failure analysis, the reliability and long service life of the four-wheel system in complex environments can be ensured. At the same time, the test results should provide direct basis for design improvement (such as material selection and sealing structure optimization), thereby reducing the after-sales failure rate and enhancing the product's competitiveness.