Production of insulated joints
There are two types of insulated joints S (Schmitz) and MT (Münch-Thermit).
There are basically two types of insulated MT joints, simple and reinforced. Reinforced insulated joints should, however, only be used with S 49 and S 54 type rails. Here is a brief description of how an insulated MT joint is produced.
The rail should be cut and also drilled in the necessary dimensions (drilled hole spacing). The mating surfaces of the fishplates should be freed from rust and also be cleaned, so that a clean bonding of the resin adhesive can take place.
After the completion of the preparatory work, both rail ends should be aligned in height and direction with a steel ruler. The joint insert can then also be put in and fixed in position.
The synthetic resin mortar can now be mixed and applied wedge-shaped to the inner sides of the insulating fish plates. Please observe the safety instructions when dealing with the adhesive; respiratory protection masks should be worn.
The fish plates can now be attached, the insulation rolls put in and screwed together with the fish-plate screws, washers and nuts.
First of all, the two inner and then the two outer fish plate screws are tightened with a power drill (Knattermax) and tightened with a torque wrench to 1 kNm.
After a period of approximately 30 minutes the insulating joint should be checked again with a torque wrench and if necessary retightened.
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.