Description
Technical Parameters
Rail Fishplate Fastening System
The Railway Fishplate (also known as joint bar or splice bar) is a metal connecting component bolted in pairs to the sides of adjacent rail ends to form a continuous track structure . Manufactured from carbon steel grades including 45# and 50#, these plates feature tapered top and bottom surfaces that wedge against the rail head and foot when bolts are tightened, ensuring secure alignment .
Technical Specifications:
| Failure Type | Primary Cause | Characteristic Features | Prevention Method | Seasonal Pattern |
|---|---|---|---|---|
| Upper-Origin Fatigue | Fretting at top contact surface | Black oxidation zone at crack origin; micro-fissures from surface deformation | Reduce friction coefficient; improve surface finish | Year-round |
| Lower-Origin Fatigue | High tensile stress at 3rd/4th bolt holes | Faster crack propagation; larger plastic zone | Maintain bolt torque; reduce rail gap | Peaks in winter |
| Brittle Fracture | Coarse grain size (ASTM 1-2) | Cleavage facets; minimal plastic deformation; fails at 5-10mm crack | Strict quality control; fine-grain heat treatment | Sudden, no warning |
| Corrosion Fatigue | Coastal/tunnel environments | Multiple crack initiation sites from pitting | Hot-dip galvanizing; stainless steel options | Accelerated in humidity |
| Fretting Wear | Micro-motion between contact surfaces | Surface deformation; oxide debris; friction-induced damage | Increased clamping force; insulation | Continuous progression |
Installation & Maintenance Perspective:
- Fishplate failures account for approximately 50% of railway accidents; 1987 Lanzhou line accident caused by simultaneous fishplate and rail fracture led to derailment, fire, and 20-hour traffic interruption
- Cracks originate from fretting fatigue between fishplate and rail contact surfaces, driven by micro-vibration, friction wear, and clamping force loss-three primary factors: friction coefficient, contact pressure, and slip amplitude
- Winter failures increase significantly due to larger rail gaps creating additional tensile stress at 3rd and 4th bolt holes
Maintenance & Operational Perspective
- Wedge-shaped design: top and bottom surfaces taper inward to create even alignment when bolts are tightened, wedging firmly against rail head bottom and rail foot top
- Reduces peak bending moments at rail joints by up to 40% compared to unjointed sections, distributing dynamic loads across connected rails
- Bolt hole geometry: elliptical counter-sunk holes prevent bolt rotation during tightening; 8.8 grade high-strength bolts feature two raised rings on head for identification, 10.9 grade has flat tapered head
Gnee Professional supplier
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