How To Install Railway Fish Plates and Q&A

I. Precise Installation Of Railway Fish Plates

1.1. Pre-construction Preparation:

Check “Workpiece”: Carefully verify the model of the fish plate, and inspect for any scratches, dents, or rust. Thoroughly clean the steel rail gap area and the inner side of the fish plate with a wire brush to ensure that the contact surface is free of any oil, rust, or impurities.

Check “Tools”: Confirm that the torque wrench is calibrated and its range covers the tightening torque requirements for the bolts.

1.2. Standardized Installation Procedure:

Positioning and Centering: Place the fish plate smoothly on the rail joint, ensuring it is fully in contact with the rail waist and bottom, and the center line of the bolt holes is aligned with the center line of the rail.

Apply Lubricant: Apply a small amount of specialized lubricant (such as molybdenum disulfide) to the threads of the bolt and the supporting surface of the nut. This not only prevents seizing but also ensures that the applied torque is ultimately converted into a consistent preload, which is the core for ensuring uniform force on each bolt.

1.3 Initial Tightening and Final Tightening:

Insert the bolt, attach a flat washer and a spring washer, and manually tighten the nut until it feels snug.

Use a torque wrench and follow a “star-shaped diagonal” sequence (as shown in the figure below) to tighten the nut in two or three stages until the specified torque value is reached (for example, for a high-strength bolt of M24, the final torque is typically between 700-900 N·m). Do not tighten in a clockwise or counterclockwise sequence!

1.4 Final Inspection: After installation, use a feeler gauge to check if there is a continuous gap of more than 1mm between the fish plate and the rail waist. At the same time, use a track gauge to recheck the track gauge and the smoothness of the track surface at the joint, ensuring it is within the allowable error range.

II. Common Questions and Practical Answers (FAQ)

Q1: Why must the bolts of the high-strength fish plate be tightened using a torque wrench and in a specific sequence?

A: This is to ensure that the “clamping force” generated by all bolts is uniform. If the sequence is random or the torque is inconsistent, it will cause uneven pressure on the contact surface of the fish plate and the rail, resulting in a “see-saw” effect. Under the repeated impact of train loads, the bolts with greater force will fatigue first, leading to a chain reaction and ultimately causing the entire joint to fail.

Q2: After installation, shortly after, there are “rust flow” marks at the contact edge of the fish plate and the rail. Is this normal?

A: This requires vigilance. This is usually the initial manifestation of contact corrosion. It indicates that the anti-corrosion layer on the contact surface may have been damaged, or there are tiny gaps where moisture has infiltrated and formed an electrolytic reaction. Immediately conduct a detailed inspection and clean the area, and reapply the specialized anti-corrosion coating to prevent the corrosion from deepening into the interior.

Q3: When the fish plate makes an abnormal noise (a “clicking” sound) during a train passage, what could be the cause?

A: The abnormal noise is an alarm for “micro movement” at the joint. The main reasons are: 1) The bolt pre-tightening force is insufficient, causing the fish plate and the rail to have a slight relative sliding under the force; 2) There are contaminants, such as fine sand particles, on the contact surface, which produce friction sounds under pressure; 3) This phenomenon usually disappears quickly during the initial running-in period. It is recommended to first recheck the torque of all bolts, and if the problem persists, disassemble for inspection and thoroughly clean the contact surface.

Q4: How can one determine if a high-strength fish plate has reached the end of its lifespan and needs to be replaced?

A: Any of the following situations should prompt immediate replacement:

Visible cracks: Especially around the bolt holes and at the waist section where the cross-section changes, any minor cracks must be scrapped.

Excessive wear: The contact surface between the fish plate and the rail head base and the rail bottom shoulder has a depth of more than 2mm of crushing or wear.

3. Structural bending or deformation: The fish plate has undergone plastic bending and cannot closely adhere to the rail.

The bolt holes have been worn into an ellipse: The bolt holes have been worn out by long-term impact and lost their precise positioning ability for the bolts. The high-strength tail fin plate, a component that combines the wisdom of materials science and structural mechanics, is worth much more than its own weight. From the meticulous selection of materials to the precise “millimeter-level” installation, and then to the daily meticulous inspections and maintenance, every step is infused with our responsibility for safety.

Supplier

Luoyang Fonyo Heavy Industries Co., Ltd,founded in 1998,is a manufacturer in railway casting parts.Our factory covers an area of 72,600㎡, with more than 300 employees, 32 technicians, including 5 senior engineers, 11 assistant engineers, and 16 technicians.Our production capacity is 30,000 tons per year. Currently, we mainly produce casting, machining, and assembly for locomotive, railcar, high-speed trains, mining equipment,wind power,etc.
We are the railway parts supply to CRRC(including more than 20 branch companies and subsidiaries of CRRC),Gemac Engineering Machinery,Sanygroup, Citic Heavy Industries,etc. Our products have been exported to Russia, the United States, Germany, Argentina, Japan, France, South Africa,Italy and other countries all over the world.