A variety of heavy-duty clips are used to fasten rails to the underlying base plate or sleeper. One widely used type in South America is the track clamp elastic rail clip, produced from round or square steel bar in spring steel grade 60Si2MnA or equivalent. This clip offers increased elasticity and fatigue resistance, providing a relatively long service life under heavy traffic. This article explains its design, specifications and applications.
Working Principle of the Track Clamp Clip
The track clamp clip is shaped so that it deforms elastically after installation, generating a clamping force that acts on the rail base. This clamping force prevents longitudinal and lateral displacement of the rail relative to the sleepers, while the elastic design reduces fatigue and wear of track components. The dual spring arm structure absorbs vertical and lateral forces generated by trains, and the central bend provides additional protection against rail tilt, enhancing overall track stability and safety.
Material and Heat Treatment
The clip is manufactured from spring steel such as 60Si2MnA, 55Si7 or equivalent grades, in round or square bar form. The chemical composition of 60Si2MnA includes carbon 0.56 to 0.64 percent, silicon 1.60 to 2.00 percent and manganese 0.60 to 0.90 percent. After forming, the clip is hardened and tempered to a hardness of 42 to 47 HRC, achieving a fatigue life of 3 to 5 million cycles without breaking. The steel grades follow the reference standards GB/T 1222 and DIN 17221.
Dimensional Range and Toe Load
| Wire diameter | Weight | Toe load |
|---|---|---|
| 12 mm | 0.18 kg | 200-400 kgf |
| 14 mm | 0.30 kg | 400-600 kgf |
| 16 mm | 0.44 kg | 500-700 kgf |
| 18 mm | 0.59 kg | 800-1000 kgf |
| 20 mm | 0.76 kg | 1100-1400 kgf |
| 25 mm | 0.49-0.68 kg | 1200-1500 kgf |
The clip diameter range is 16 mm to 25 mm for common heavy-duty applications. The toe load increases with wire diameter, providing higher clamping force for heavier rail sections and higher axle loads.
Surface Treatment
Surface treatments include plain oiled finish, oxide black, color painting, zinc plating and hot-dip galvanizing. For humid and coastal regions, hot-dip galvanizing and Dacro coating provide better corrosion protection. The oxide black and color painted finishes are economical for dry inland climates. The choice of surface treatment should consider the local climate, traffic density and expected maintenance interval.
Applications, Installation and Maintenance
Track clamp elastic rail clips are widely used in South American railway systems on heavy-haul mineral lines, main lines and industrial tracks. The fastening system typically includes the clip, tie plate, rail insulator, screw spikes or dog spikes, and a rail pad. The tie plate is made of Q235 steel or ductile iron, the insulator of PA66 reinforced with glass fiber, and the rail pad of rubber, EVA or other elastic material. This complete system provides stable and durable rail fastening under severe service conditions.
Install the clip with the correct tool so that the bent section presses precisely on the rail foot, and verify that the insulator is correctly seated. The clamping force should follow the system specification; over-tightening can cause permanent deformation. During inspection, check the clips for cracks, corrosion and loss of toe load, and replace damaged clips promptly. Store clips in dry conditions and protect the surface finish during transport.
Frequently Asked Questions
What is a track clamp elastic rail clip? It is a heavy-duty spring steel clip that clamps the rail base to the sleeper through elastic deformation, preventing rail movement and absorbing train impacts.
What material is used for these clips? Spring steel 60Si2MnA, 55Si7 or equivalent, hardened and tempered to 42 to 47 HRC.
What is the typical toe load? Toe load ranges from about 200 kgf for a 12 mm clip to 1200-1500 kgf for a 25 mm clip.
Where are these clips mainly used? They are widely used in South America on heavy-haul mineral lines, main lines and industrial tracks.
What surface treatments are available? Plain oiled, oxide black, color painting, zinc plating, hot-dip galvanizing and Dacro coating.
How is the fatigue life verified? The clips are tested to 3 to 5 million cycles without breaking, depending on the wire diameter.
