Types and Compatibility of High-Speed Railway Fastening Systems
What are the core differences between WJ-7 and WJ-8 fasteners?
The WJ-7 type is an elastic separated fastener that bears lateral forces through anchor bolts, while the WJ-8 type is an elastic non-separated fastener that relies on the track slab shoulder to bear lateral forces, which is the most core structural difference between the two. In terms of gauge adjustment range, the WJ-7 type has continuous stepless adjustment of -12～+12mm, and the WJ-8 type has stepwise adjustment of -10～+10mm, with different focuses on adjustment accuracy and range. They are suitable for different track types: the WJ-7 type corresponds to CRTS Ⅰ type ballastless track, and the WJ-8 type is suitable for CRTS Ⅱ type and independently developed CRTS Ⅲ type track slabs. In terms of application scenarios, the WJ-7 type is used in lines such as Wenfu and Harbin-Dalian, while the WJ-8 type is widely used in high-speed railways such as Beijing-Shanghai and Zhengzhou-Xi'an. The differences in bearing mode and adjustment characteristics enable them to accurately match the structural design requirements of different track slabs.
What is the adaptive speed and track type of the elastic bar type Ⅳ fastener?
The elastic bar type Ⅳ fastener is suitable for the Ⅲb type shoulderless prestressed concrete ballasted track with a maximum speed of 250km/h, which is an optimized and improved product based on the elastic bar type Ⅲ fastener. Its design positioning is a special fastener for medium and high-speed ballasted tracks, which bears lateral forces through pre-embedded iron seats and belongs to an elastic non-separated structure. The gauge adjustment range is -8～+4mm with an adjustment level of 1mm, and the height adjustment range is also graded by 1mm, meeting the geometric adjustment needs of medium and high-speed lines. This fastener has been successfully applied in the Xiamen-Shenzhen High-speed Railway, and its performance adapts to the vibration and load characteristics of 250km/h grade lines. Compared with the WJ series fasteners suitable for 350km/h, it focuses more on the installation convenience and cost balance of ballasted tracks.
What are the differences in force-bearing characteristics between elastic separated and non-separated fasteners?
Elastic separated fasteners independently bear lateral forces through anchor bolts, with more direct force transmission, which can reduce the force burden on the track slab and are suitable for shoulderless track structures. Elastic non-separated fasteners rely on the track slab or sleeper shoulder to bear lateral forces, with a simpler structure and higher installation efficiency, suitable for shoulder-equipped track designs. Separated fasteners are more flexible in adjusting the gauge and can achieve stepless adjustment, while non-separated fasteners are mostly stepwise adjusted with relatively fixed adjustment accuracy. In terms of force distribution, the separated type can avoid the impact of shoulder wear on fastener performance, while the non-separated type needs to ensure the strength and flatness of the shoulder. The force design of both structures is carried out around the track type and operating speed to ensure balanced force and long-term stability.
How to select the appropriate fastener according to the track slab type?
First, it is necessary to clarify the type of track slab (such as CRTS Ⅰ/Ⅱ/Ⅲ type) and structural characteristics (with or without shoulder), which is the core basis for selecting fasteners. CRTS Ⅰ type shoulderless track slabs need to be matched with elastic separated fasteners (such as WJ-7 type), which use anchor bolts to bear lateral forces and adapt to the shoulderless design. CRTS Ⅱ/Ⅲ type shoulder-equipped track slabs are suitable for elastic non-separated fasteners (such as WJ-8 type), which transmit lateral forces through the shoulder with a more matched structure. At the same time, the designed speed of the line should be considered: WJ series high-end fasteners are preferred for 350km/h high-speed lines, and elastic bar type Ⅳ/V fasteners can be selected for 250km/h lines. It is also necessary to check the adjustment parameters of the fasteners to ensure that they can meet the geometric correction needs of later track maintenance, and finally achieve the precise adaptation between the fasteners and the track slab.
What are the application scenarios and technical advantages of the elastic bar type V fastener?
The elastic bar type V fastener is suitable for the Ⅲa type shoulder-equipped prestressed concrete ballasted track with a maximum speed of 250km/h, and has been successfully applied in projects such as Nanning Line and Wuhan-Guangzhou Intercity Railway. It bears lateral forces through the sleeper shoulder, belongs to an elastic non-separated structure, has a simple structure and convenient installation, and can reduce construction costs and cycles. The gauge adjustment range is -8～+4mm, the height adjustment range is 10mm, and the adjustment level difference is 1mm, which can meet the daily maintenance needs of medium and high-speed lines. This fastener has excellent fatigue resistance, can adapt to frequent train dynamic load impacts, and extend the service life. Compared with the elastic bar type Ⅳ, it is more suitable for Ⅲa type sleepers, forming a complement in the adaptability of different rail types and enriching the fastener options for medium and high-speed ballasted tracks.