Key Points for Fastening System Maintenance and Troubleshooting
- How to check if the clamping force of elastic clip fasteners is normal?
Use an elastic clip clamping force detector to apply a vertical force in the middle of the elastic clip and measure the deformation. Judge according to the corresponding relationship between deformation and clamping force. Generally, the clamping force of elastic clips should be within ±10% of the design value. For example, the design value of the clamping force of WJ - 7 fasteners is 9 - 13kN.
- What are the common causes of bolt loosening?
Train vibration, insufficient torque, thread wear, and environmental corrosion are common causes. Long - term train vibration attenuates bolt pre - load. Insufficient torque during installation (e.g., high - strength bolts with torque less than 100N·m) easily leads to loosening. Thread wear reduces connection friction, and a humid environment rusts bolts, weakening the fastening effect.
- What are the hazards of spike pulling out and preventive measures?
Spike pulling out makes the connection between the rail and the sleeper fail, resulting in gauge changes and track unevenness, affecting driving safety. Preventive measures include using high - quality spikes, ensuring anchoring depth (e.g., spike anchoring depth in wooden sleepers ≥120mm), regularly checking spike anchoring status, and promptly replacing loose or damaged spikes.
- What impact does the damage of under - rail pads have on the fastening system?
Damage to under - rail pads (such as rubber pad aging and cracking, polyurethane pad wear) changes track elasticity and makes the fastening system unevenly stressed. For example, local pad voids cause concentrated stress on elastic clips, accelerating elastic clip fatigue and may also loosen bolts. Damaged pads need to be replaced in time.
- How to perform torque re - tightening in the maintenance of the fastening system?
According to the specified cycle (e.g., quarterly), use a torque wrench to re - tighten the bolts. First, check if the bolts are rusted or deformed, clean the threads, and then re - tighten to the design torque value. For example, for elastic clip fastener bolts, set the torque wrench to the specified torque (e.g., 120 - 150N·m) and re - tighten the bolts one by one to ensure the stability of the fastening system.