Turnout inspection and adjustment requirements

Requirements
At present, the close fit adjustment of the inner locking turnout is generally adjusted on site according to the requirements of "2mm locking, 4mm non-locking". Regarding the close fit adjustment requirements of "2mm locking", the "Signal Maintenance Rules (Technical Standards) Explanation" published in 2002 mentioned: "To prevent the close fit between the point rail and the base rail from being too large, a 2mm locking test should be carried out"
Interpretation
Since the close fit adjustment rod of the inner locking installation device is relatively long, the rod will deform in rigidity when the "4mm non-locking" foreign body clamping inspection is carried out. Therefore, in order to meet the "4mm non-locking" requirement, it is easy to adjust the close fit of the point rail too large. Due to factors such as the "creeping" and "bulging" phenomena of the point rail caused by changes in ambient temperature, and the change in the state of the turnout caused by the train passing through the turnout, excessive close fit will increase the probability of turnout conversion blocking. Therefore, in order to avoid excessive close fit of the point rail, the on-site inspection is generally carried out according to the requirements of "2mm locking, 4mm non-locking".