What is the pull-out force of a spike?
What is the pull-out force of a spike? Comparative analysis of performance of different types
One of the core functions of a railway spike is to provide sufficient pull-out force to ensure that the rail does not slip or loosen longitudinally during train operation.
The pull-out force of different types of spikes varies significantly. Generally speaking, the pull-out force of ordinary square-headed spikes is about 4–6 kN, while that of spiral spikes can reach 8–12 kN, and the pull-out force of the high-strength spring-clip spike matching system even exceeds 20 kN.
The pull-out force is affected by many factors, including the material, shape, penetration depth, ballast structure, and the matching accuracy between the spike and the sleeper. For example, when using spiral spikes in concrete sleepers, nylon sleeves are required to enhance the grip to fully exert their performance.
In wooden sleepers, ordinary spikes are fixed by friction with the wood and are suitable for tracks with lighter loads.
Understanding the pull-out performance of different spikes is of great significance for designing safety factors, formulating maintenance cycles, and selecting solutions. Especially in high-frequency vibration or heavy-load lines, the reliability of spikes is directly related to the stability of the track structure and operational safety.
