Nabla RNTC blade for Elastic Rail Fastening System

The Nabla RNTC blade is a core component of the Nabla elastic rail fastening system, specifically the RNTC variant often associated with STEDEF track technology. Shaped like a thick trapezoidal shovel with a central hole, it functions as a spring blade to secure rails to sleepers. 

Key Features & Purpose

• Elastic Fastening: The blade generates a dynamically stable toe load (clamping force) of 2500 DaN when the securing nut is torqued.

• Vibration Dampening: Its design is engineered to absorb and disperse shocks and vibrations, which is critical for high-speed lines (like the French TGV) and urban transit.

• RNTC Specification: The RNTC model is specifically designed for use on profiled concrete sleepers and is compatible with grooved rail types such as 60Ri1, 60Ri2, 62Ri1, and 62Ri2.

• Versatile Application: It is suitable for ballasted tracks, slab tracks, and diverse environments including concrete, asphalt, or green track beds. 

Technical Specifications (Standard Blade)

• Material: High-quality alloy spring steel (e.g., 60Si2MnA or 60Si2CrA).

• Hardness: Typically ranges between HRC 42–47 or HRC 51–55 depending on specific manufacturer standards.

• Thickness: Generally available in 4mm or 4.5mm.

• Durability: Tested for fatigue life of 3 to 5 million cycles without cracking.

• Finish: Often painted (commonly red) or treated with plain oil or zinc plating for corrosion resistance. 

System Components

The Nabla RNTC blade operates within a larger assembly consisting of:

• Nabla Blade: The elastic clip.

• Rail Insulator: Provides electrical insulation and lateral stability.

• Screw Spike & Nut: High-strength bolt (Grade 5.6 or 8.8) that presses the blade against the rail foot.

• Special Spring Washer: Protects the thread and maintains tension.

• Rail Pad: Resilient material placed between the rail and sleeper for further damping.