A rail fish plate is a joint reinforcement device that restores effective sectional strength at rail gaps, preventing excessive deflection, vibration, and impact loads that would otherwise accelerate rail end fatigue. GNEE RAIL supplies fish plates for GB standards, UIC standards, DIN536 and QU crane rail systems, JIS rails, AS1085 rails, BS11 profiles, and AREMA/ASCE rails, and provides bolt-grade matching and installation reference guidance.
What is a rail expansion joint?
A rail expansion joint (or breather switch) is a specialized railway track mechanism designed to allow longitudinal movement, expansion, and contraction of rails caused by temperature variations, bridge movement, or, in some cases, mining subsidence. It prevents buckling, deformation, and breakage in long sections of track, particularly in Continuously Welded Rails (CWR).
Key Aspects and Usage Examples
- Bridge Application: Mandatory on bridges with expansion joints to accommodate movement of the base structure.
- Temperature Management: Used in CWR to prevent buckling during extreme hot or cold temperatures, usually by allowing relative movement of two adjacent rails.
- Specific Locations: Commonly installed near tunnels, on bridges, and at structural joints.
- Mechanism: Uses tongue and jaw rails that move against each other while maintaining a constant track gauge.
- Types: Can be designed with or without guard rails, suitable for heavy loads (up to 35 tons axle load).
Why is there a gap before the track?
Gaps (or rail joints) are left between steel railway tracks primarily to allow for thermal expansion during hot weather. Since steel expands when heated, these gaps prevent the tracks from buckling, deforming, or warping, which could cause serious train derailments.
- Thermal Expansion: In summer, the sun heats the metal rails, causing them to increase in length. Without a gap, the rails would push against each other and bend.
- Preventing Buckling: When rails expand and have no space to expand, the track bends sideways or upwards, known as buckling.
- Contracting in Cold: Conversely, during winter, the steel contracts. The gaps prevent the bolts holding the tracks together from breaking due to high tension.
- Traditional Construction: While many modern lines use continuous welded rail (CWR) to minimize noise, older, conventional tracks are bolted together in sections, requiring these gaps at regular intervals.
What types of rail joints are there?
Rail joints are essential components connecting adjacent rails, categorized by support method, alignment, function, and fastening method. Key types include supported/suspended joints, staggered/opposite joints, compromise joints (different rail sizes), insulated joints (for signaling), and welded/bolted joints. These ensure track continuity, safety, and accommodate expansion.
Key Rail Joint Types
Based on Position to Sleepers:
- Suspended Joint: The joint is suspended between two sleepers. The most common type, allowing for easier maintenance.
- Supported Joint: The joint rests directly on a sleeper.
- Bridge Joint: A specialized suspended joint where a metal bridge plate supports the rail ends.
Based on Position on Track:
- Staggered Joint: Joints on opposite rails are not aligned; used on curves to prevent rocking.
- Opposite (Square) Joint: Joints on both rails are at the same cross-section.
Based on Function/Application:
- Compromise Joint: Connects two rails with different profiles or sizes.
- Insulated/Glued Joint: Uses insulating materials (e.g., polyurethane) to electrically isolate rail sections for signaling, preventing short circuits.
- Joggled/Bulge Joint: Used for rapid, temporary repairs of broken or cracked welded rails.
- Expansion Joint: Allows for thermal expansion and contraction of the rail, often used on long bridges.
| Joint Type | Key Specification / Description |
|---|---|
| Standard Rail Joint (Fish Plate) | - Profile: Matches the rail section (e.g., UIC 60, 136RE). - Length: Typically 600mm or 800mm per side. - Holes: 4 or 6 bolt holes per bar. |
| Insulated Rail Joint (IRJ) | - Material: Steel core with composite insulating end-posts/plates, or full epoxy composite. - Electrical Resistance: >10⁸ Ω. |
| Compromise Rail Joint | - Design: Connects two different rail profiles (e.g., UIC 54 to UIC 60). - Profile: Each side is machined to match its respective rail section. |
| Joggled Rail Joint | - Feature: Has a depressed (joggled) section to allow continuous rail head surface for smoother wheel passage. |
| Bridge Rail Joint | - Design: Often reinforced (thicker web/longer length) for high-stress locations like bridge approaches. |
| Glued Insulated Joint | - Construction: Steel bars bonded to composite insulation using high-strength adhesive for improved durability. |
| Welded Rail Joint (for CWR) | - Type: Flash-butt or thermite weld. - Specification: Weld must meet mechanical properties equal to or greater than the parent rail. |
| Expansion Joint (for BRE) | - Feature: Allows controlled thermal expansion in long rails on bridges or in extreme temperature zones. |
Based on Assembly Method:
- Bolted Joint: Traditional connection using fishplates and bolts.
- Welded Joint: Rails are welded together to eliminate the gap, providing a smoother ride.
Founded in 2008, GNEE RAIL is a leading global manufacturer and supplier of railway components, specializing in high-quality rail fish plates (joint bars/splice bars) with strong production capacity and global service capabilities.
Our rail fish plate portfolio is comprehensive and compliant with international standards including UIC, AREMA, BS, DIN, and GB, covering light rail (8kg-30kg), heavy rail (38kg-75kg), and crane rail (QU70-QU120) systems. We offer diverse types such as insulated joint bars, bulged fish plates, and compromise rail joints,with precise specifications (4-hole/6-hole, 24-inch/36-inch), ensuring excellent mechanical performance.We uphold strict quality control supported by ISO 9001:2015 certification, an in-house inspection center, and third-party audits by SGS and BV. Our one-stop service includes customization, production, packaging, and after-sales support, tailored to clients' project needs.