Insulated rail joints separate electric circuits in tracks and turnouts. As they are used in continuously welded rails (CWR), they must be able to transfer longitudinal forces arising in the track.
At high electric resistance, the bonded insulated rail joint IVB 30 / IVG 30, developed by voestalpine Turnout Technology Germany, is subject to considerable mechanic and dynamic stress.
Design and Function
The main characteristic of IVB 30 / IVG 30 is a 30° scarf joint in the area of the running table of the rail head. This type of contact area makes it possible for the wheel to pass smoothly without abrupt interruptions in the insulated rail joint.
Compared to the 90° insulated rail joint, this is more resistant to wear and has a lower noise level as far as the wheel transfer area is concerned. To reduce wear even further a fine pearlitic hardening of the wheel transfer area or the use of HSH rails is recommended.
Due to the fact that a scarf joint can take up only few longitudinal forces, it is only to be found in the rail head. In the subjacent area, including the rail base, the construction is such that the longitudinal forces are transmitted by a 90° joint
Depending on axle load and dynamics, fishplates or reinforced fishplates can be used as connecting elements. The reinforcement increases the section modulus and thereby decreases the deflection of the insulated rail joint. The insulated steel fishplates secure the joint via a high-strength bolted connection.
In high-speed traffic and heavy haul traffic, in industrial railways and standard gauge railways,the reinforced IVB 30 / IVG 30 joint is used.
In lightrailway traffic the standard IVB 30 / IVG 30 joint is used.