Rail joint coupling parts include cleats, bolts, nuts, washers, etc.
(1) Rail splint
The role of the splint is to clamp the rails. The cleats used in China's standard rails are all double-headed, which is suitable for 60 kg/m rails and various types of rails.
The diameter of the splint round bolt hole is slightly larger than the bolt diameter, and the length of the oblong bolt hole is slightly larger than the length of the protrusion under the bolt head. Relying on the difference between the diameter of the rail bolt hole and the bolt diameter, and the difference between the diameter of the circular bolt hole of the clamp plate and the diameter of the bolt, the rail can be expanded and expanded with the change of rail temperature within the range of reserved rail joint value.
(2) Joint bolts
The bolt should make the rail and splint connection firm and reliable, and fit tightly, but it must be ensured that when the temperature of the rail changes, the splint can have a certain longitudinal moving position. The larger the diameter of the bolt, the stronger the tightening force, but increasing the diameter of the bolt will inevitably increase the bolt hole diameter on the rail and splint, thereby weakening the strength of the rail and splint. Therefore, bolts should be made of high-carbon steel and heat-treated high-strength bolts.
(3) Rail seams
In order to meet the needs of thermal expansion and contraction of rails, China's seam ordinary lines generally leave rail joints at rail joints. The rail gap should not be too small, so as to avoid expansion of the rail runway or bending and pulling off bolts when the rail is elongated at high temperature without room for extension, but it should not be too large, so as to avoid the rail shrinking and bending and pulling off the bolts at low temperatures. Therefore, there should be reserved rail joints when laying steel rails.