Fastenings connect the rails with the sleepers by means of a ribbed plate to form a track skeleton. This skeleton (the track) must be torsionally stiff and not slip. The rail must not move in the longitudinal direction, tip over or twist.
The pressure of the rail fastening should be approximately 180 - 220 kN. An elastic mounting of the rails (using a plastic pad Zw) reduces the high wear of the rail fastening at the same time. This rail pad also increases the friction between the rail and the fastening. In a normal track laid on wood sleepers a ribbed plate made of steel is attached to the sleeper. The laterally arranged ribs (swallow tails) of this ribbed plate give the rail the necessary gauge retention in the transverse direction. The hook bolts are inserted in the semi-circular cut outs in the swallowtails of the ribs. A clamping plate or clip is fitted, which has the task of pressing the rail onto the ribbed plate by means of a spring ring (only on track with K fastenings, on KS track a washer is used) and a nut. A so-called track with W fastenings is fitted on concrete sleepers.
The W-track is held in gauge by the angle guide plates arranged on both sides of the rail foot. These are inserted in the recesses in the concrete and secured with a coach screw, which is inserted into a plug cast into the concrete sleeper which secures the rail against lateral displacement. By installing an insulation insert under the angle guide plate the rail is insulated against the sleeper (so that no current can flow).
You can find suitable specialist literature to 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.