The longitudinal movements (so-called walking) of the rails on the sleepers in the ballast bed must be prevented as much as possible. For this purpose, protective wandering clamps can be mounted on the rails. The clamps are placed where rails tend to migrate in case of great pressure and tensile forces that act on the track.
Wandering protection clamps are mounted directly next to the sleepers on the rail foot. Earlier types were screwed; today, the attachment is done by wedging or spring-clamping action.
Wandering protection Mathée:
There have always been aids to prevent walking of the rails. One of the most reliable and effective ways is the wedge clamp system according to Mathée.
The causes of the rail migration are:
- The Impact of the wheels against the stop rail when staking at the joint (e.g., inaccurate lashing or wear and tear.
- The thrust that the wheels and even more impactful is the braking of the wheels exerted in the direction of travel.
- The deformation of the rails under the rolling Wheel.
- The expansion of the rail due to temperature fluctuations.
The wandering protection-system Mathée consists of three parts: the stem piece and 2 brackets.
The stem piece is forged from wide iron and is angled. It lies with a 1: 6 inclined surface perpendicular to the base of the rail to the sleeper edge. When using concrete sleepers, the angle is changed accordingly. The stem piece has two inwardly curved webs, which are carried out both in the vertical and in the horizontal at a certain inclination.
The 2 brackets have the same slope as the wedge surfaces. These brackets include the rail foot and the angled webs of the stem piece. By driving the brackets, the stem piece is particularly tightly clamped to the rail. The foot of the stem piece lies firmly on the threshold.
The anti-migratory effect of the Mathée clamp is based on a double wedge effect. The clips can be grinded from time to time and thereby the effect can be restored. The protective wandering clamps can be used again and again even after dismantling the track system.
You can find suitable specialist literature about the topic here:
The Basic Principles of Mechanised Track Maintenance
This book is dedicated to the many people involved in the day to day planning and performance of track maintenance activities. Providing a practical approach to everyday challenges in mechanised track maintenance, it is not just intended as a theoretical approach to the track system.
Railways aim at transporting people and freight safely, rapidly, regularly, comfortably and on time from one place to another. This book is directed to track infrastructure departments contributing to the above objective by ensuring the track infrastructure’s reliability, availability, maintainability and safety – denoted by the acronym RAMS. Regular, effective and affordable track maintenance enable RAMS to be achieved.