Torque Standards and Maintenance Key Points for Fastening Systems
- How are the torque standards for different parts of the fastening system determined?
They are determined based on factors such as the material, dimensions, stress conditions of track components, and the designed bearing capacity. For example, for the fasteners connecting the rail and the sleeper, considering the vibration, lateral and longitudinal forces generated during train operation, appropriate torque values are determined through mechanical calculations and simulation tests, generally between 80 - 150N·m, to ensure that the elastic clips provide sufficient clamping force without damaging the components.
- What are the impacts of insufficient or excessive torque on the track?
When the torque is insufficient, the clamping force of the elastic clip is not enough, the rail is prone to longitudinal and lateral displacement, the gauge changes, and the wear of track components is aggravated, which may seriously affect driving safety. Excessive torque may cause bolt breakage, fatigue damage of elastic clips, reduce the service life of components, and also cause the sleeper to bear additional stress, and cracks may appear.
- How to detect the torque of the fastening system during daily maintenance?
Regularly detect with a torque wrench. Generally, spot - check key areas (such as turnout areas and curve sections) monthly, and conduct a general inspection of the entire line quarterly. Accurately set the torque wrench on the bolt, slowly apply force in the specified direction, read the torque value displayed on the wrench, and compare it with the standard value. If the deviation exceeds ±5%, adjustment is required.
- What measures should be taken when abnormal torque is found?
If the torque is insufficient, use a torque wrench to retighten according to the standard torque value, and check whether components such as elastic clips and bolts are damaged. Replace them if necessary. If the torque is too large and causes component damage, replace the damaged components in time, reinstall and tighten according to the standard torque. At the same time, analyze the reasons for excessive torque, such as whether it is caused by improper installation operations or tool failures.
- Are there any special requirements for the torque maintenance of the fastening system in different seasons?
In winter, due to low temperatures and brittle materials, the torque adjustment should be appropriately reduced to avoid component breakage caused by excessive torque. Generally, it can be in the lower limit range of the standard value. In summer, due to high temperatures and material expansion, the torque needs to be appropriately increased to prevent insufficient torque caused by component expansion and loosening. It can be in the upper limit range of the standard value. At the same time, increase the inspection frequency to prevent abnormal torque caused by temperature changes.