Product Overview

A“bulged”fishplate—also known as a raised-center fishplate—is a specialized type of rail joint bar used in railway tracks. Unlike standard, flat-profile fishplates, this design features a raised, protruding section in the middle, which is engineered to accommodate the specific installation and connection requirements of certain types of rail joints.

This design is primarily intended for situations where a raised weld bead (excess weld metal) exists near the weld zone after rail welding. When installing standard, flat-profile fishplates, the raised weld bead can cause interference, hindering proper contact and clamping between the fishplate and the rail. By incorporating a protruding (bulged) section in the middle of the fishplate, space is created to accommodate the raised weld bead, thereby facilitating the installation of the fishplate.

 

Working Principle of Bulged Fishplates

• Principle of Weld Clearance: When rails are joined by welding, a "weld bead" (excess weld metal) may form in the welded area, rising above the original surface of the rail. If a standard, flat-profile fishplate (joint bar) is used before the welded joint has undergone the required post-weld finishing, the fishplate may interfere with this raised weld area. A "bulged" (or recessed-clearance) fishplate features a raised section in its middle, providing the necessary space to accommodate such protrusions.
• Joint Clamping Principle: Bulged fishplates are installed on both sides of the rail and secured using matching bolts and nuts. Once the bolts are tightened, the fishplates exert a clamping force on the rail joint, thereby meeting the connection requirements specified in the product design. The performance of this connection depends on the material and structural dimensions of the fishplates, the specifications of the bolts, the tightening force applied, and the condition of the rail joint.
• Adaptation Principle of the Bulged Joint Bar: A bulged joint bar does not enhance the strength of the rail directly through its bulged structure; rather, it modifies the geometry of the bar’s midsection to accommodate specific joint conditions where standard, flat joint bars cannot be easily installed. Consequently, the primary design value of the bulged structure lies in providing spatial clearance and ensuring a proper fit for clamping the rail joint.

 

Key Characteristics of Bulged Fishplates

1. Special bulging structural design
2. Clearance provided for weld zones
3. Facilitates the installation of specialized joints
4. Bolted connection method
5. Customizable based on rail specifications

A“bulged”fishplate—also known as a raised-center fishplate—is a specialized type of rail joint bar used in railway tracks.