Nabla RNTC Insulator for Elastic Rail Fastening System

The Nabla RNTC insulator（also known as Nabla bumper） is a specialized component used within the Nabla RNTC rail fastening system, primarily designed for ballastless tracks and concrete sleepers. It serves as a "stop" or spacer that provides electrical insulation and lateral stability for the rail. 

Key Functions & Features

• Electrical Insulation: Prevents electrical current from leaking from the rails to the concrete sleepers, ensuring the integrity of signaling systems.

• Gauge Adjustment: Helps maintain and adjust the rail gauge (the distance between two rails).

• Load Distribution: Acts as a buffer between the steel rail and the fastener components to distribute lateral forces.

• Material: Typically manufactured from Nylon PA66 reinforced with 30–35% glass fiber for high strength and durability. 

Technical Specifications

System Context

The RNTC (and related RNTS) systems are often used on high-speed lines, such as the French TGV network, where they are paired with elastic Nabla clips and rubber pads to provide superior ride quality and vibration damping. 

System Compatibility

• Nabla RNTC: A classic STEDEF fastener system used on profiled concrete sleepers.

• Nabla Evolution: An advanced version designed for simplified maintenance and enhanced lateral force absorption in tight radius curves.

• Nabla Tram: Specifically adapted for embedded slab tracks in urban environments with higher insulation requirements (>20 kΩ).