Description
Technical Parameters
Rail Screw Spike Fastening System
The Railway Screw Spike (also known as rail screw or sleeper screw) is a threaded steel fastener engineered to provide superior pull-out resistance for securing rails to wooden sleepers or sleeper inserts . Manufactured from medium-carbon steel grades including 35#, 45#, 40Mn2, and 20MnSi, with property classes ranging from 4.6 to 8.8, these spikes achieve tensile strengths of 400–800 MPa depending on grade specification .
Technical Specifications:
| Parameter | Ss5 Series | Ss8 Series | Ss25/Ss36 Series | ASTM A66 High-Tensile |
|---|---|---|---|---|
| Standard | UIC864-1 | UIC864-1 | UIC864-1 | ASTM A66-87 |
| Material Grade | Q235, 35# | 35#, 45# | 45#, 40Mn2 | 1045 / 45# |
| Property Class | 4.6 | 5.6 | 8.8 | 120,000 psi min |
| Tensile Strength | ≥400 MPa | ≥500 MPa | ≥800 MPa | ≥829 MPa (120ksi) |
| Yield Strength | ≥240 MPa | ≥300 MPa | ≥640 MPa | ≥635 MPa (92ksi) |
| Elongation | ≥22% | ≥20% | ≥14% | ≥14% |
| Thread Diameter | M24 | M24 | M24 | 3/4", 7/8", 15/16" |
Installation & Maintenance Perspective:
- High-Tensile Variants: Premium screw spikes achieve tensile strength of 120,000 psi (≥829 MPa) with yield strength of 92,000 psi (≥635 MPa) and elongation ≥14%, meeting ASTM A66 requirements for cold bending 90° without cracking .
- Material Composition: Carbon steel grades 35# and 45# contain 0.32–0.50% carbon with manganese 0.50–0.80%, while alloyed grades like 40Mn2 incorporate 1.40–1.80% manganese for enhanced hardenability and strength .
- Proof Load Testing: Grade 8.8 spikes undergo proof load verification at ≥587 MPa, ensuring elastic behavior under maximum design loads without permanent deformation .
Maintenance & Operational Perspective
- Thread Engagement Principle: The helical thread (typically M24 pitch) distributes pull-out forces along the entire embedded length, engaging a larger volume of wood fibers compared to the friction-only mechanism of dog spikes .
- Pull-Out Resistance Advantage: Laboratory testing demonstrates screw spikes achieve 50–100% higher pull-out resistance than equivalent dog spikes, though lateral (thrust) resistance is approximately 50% lower due to the thread's directional nature .
- Thread Profile Options: Available in multiple thread configurations including standard machine screw threads, round threads (NF-F 50014), and specialized profiles for concrete sleeper inserts or plastic dowels .
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