What is the role of fish bolts in rail joints?
Nov 06, 2025
Fish bolts fasten rail joint bars (also known as fish plates) to the ends of two steel rails, which connects them and secures the joint. Their primary role is to maintain track geometry, transfer the load of passing trains to both rails, and ensure the track is stable and safe. The oval-shaped neck on the bolt head prevents it from rotating, allowing it to be securely tightened with a nut and spring washer.
Key roles of fish bolts
Secure connection: Fish bolts, along with the fish plates, hold the ends of two rails together to create one continuous track.
Load transfer: They help distribute the immense weight from passing trains evenly across the two connected rails, preventing excessive stress at the joint.
Track stability: By keeping the rails securely aligned, they maintain the correct spacing and height, which is crucial for a smooth and safe ride.
Preventing movement: The bolt's oval neck, combined with a nut and spring washer, prevents the connection from loosening due to vibrations, which could lead to track failure.
Allowing for expansion: The fish bolt passes through an elliptical hole in the fish plate, which provides a small amount of space for the rails to expand and contract with temperature changes without bending.
Fish Bolt Size Specifications and dimensions
| Type | Dimension | Weight (Kg) |
| HS26/55 | M22 ×55/40 Nut M22/H22/S39 | 0.45 |
| HS26/65 | M22 ×65/45 Nut M22/H22/S39 | 0.475 |
| HS26/90 | M22 ×90/45 Nut M22/H22/S39 | 0.549 |
| HS32/55 | M22 ×55/40 Nut M22/H22/S39 | 0.469 |
| HS32/65 | M22 ×65/45 Nut M22/H22/S39 | 0.503 |
| HS32/90 | M22 ×90/45 | 0.577 |
Types of Railway Bolts for Railway Construction
The railway bolts can be classified into several types, such as, Button head oval neck railway bolt, Diamond neck railway bolt, Railway bolt NF F50-008, Fish bolt, Railway bolt of Russian standard, Clip bolt, Clamp bolt and inserted bolt for Russia, anchor bolt, T-bolt clamp and other special Railway bolts, etc.
Fish bolt belongs to the series of rail bolt, or track bolt, which are used to fix 2 fish plate connections onto 2 rail tracks, GNEE RAIL fabricate fish bolt using high quality steel materials,such as Q235, 45#, 40Cr, 20Mntib,even stainless steel, covers international standards according to BS, ASTM and DIN, among others.
