The rail fastening system is an essential part of the railway track structure, composed of various rail fasteners (OTM materials). Its main function is to firmly secure the rail onto the sleeper or track slab to ensure track stability. Fastening systems can be classified into different types according to track design, application scenarios, and material, and they are equipped with different components. The most common railway fastening systems include the Elastic clip IV Fastening System, Elastic clip V Fastening System, WJ-7 Fixing System, and WJ-8 Fastening System.
Composition of WJ-7 Fastening System
The WJ-7 fastening system consists of a T-bolt, nut, flat washer, rail clip, insulating block, baseplate, rail pad (rubber pad or composite pad), insulating cushion plate, heavy-duty spring washer, flat spacer, anchor bolt, and embedded sleeve. It may also include a rail leveling pad (or filling-type pad) and a baseplate leveling pad.
Clip: Clips are categorized into Type W1 and Type X2. Type W1 is typically used in standard sections, while Type X2 is employed in low-resistance sections.
Type W1 for standard sections Type X2 for low-resistance sections
Rail Pad: Rail pads are categorized into Type A and Type B. Each type is further classified into rubber pads for standard sections and composite pads for low-resistance sections. Special attention should be paid to the fact that Type A pads are exclusively used for maintenance purposes on existing high-speed railways where Type A pads have already been implemented.
Rubber Pads for Standard Sections Composite Pads for Low-Resistance Sections
Insulating Block: Insulating blocks are categorized into Type 9 and Type 10. Type 9 is used under standard installation conditions. When the gap between the insulating block and the baseplate shoulder exceeds 1 mm, it should be replaced with Type 10.
No. 9 Insulating Block No. 10 Insulating Block
Insulating Cushion Plate: Insulating cushion plates are available in two thicknesses: 2mm and 6mm. The 6mm thick plate is used for normal installation, while the 2mm thick plate is applied for negative adjustment of the rail height position.
Insulating Cushion Plate
Embedded Sleeve: Manufactured from nylon material, it is pre-embedded in concrete sleepers or track slabs. The installation accuracy must meet the requirements specified in the drawings, with the top surface of the embedded sleeve positioned 0–1 mm below the rail seating surface of the sleeper or track slab. If the fasteners are not pre-assembled at the sleeper factory, a plastic (or other material) cover should be installed to prevent ingress of rainwater and dirt.
Leveling Pads: Leveling pads are divided into two types: rail leveling pads and baseplate leveling pads. Rail leveling pads are placed between the rail pad and the baseplate, and are available in thicknesses of 0.5mm, 1mm, 2mm, 5mm, and 8mm. Baseplate leveling pads are placed between the baseplate and the insulating cushion plate. Baseplate leveling pads come in only one specification, with a thickness of 8mm.
Rail Leveling Pad
Baseplate Leveling Pad
WJ-7 Fastening System Installation
The installation process of the WJ-7 fastening system resembles a meticulously orchestrated symphony, where every step must be executed with precision to ensure the stable performance of the fastening system. The entire installation process is divided into pre-installation preparations, pre-assembly steps, and on-site final installation steps.
Pre-Installation Preparations: Carefully select appropriate clips, rail pads, No. 9 insulating blocks, and 6mm-thick insulating cushion plates. Simultaneously, ensure thorough cleaning of the rail seating surface of sleepers or track slabs to remove dirt and debris. Remove plastic covers from embedded sleeves, clear any foreign matter and accumulated water from the sleeve cavities, and inject approximately 30g of specialized railway protective grease into each sleeve to create optimal conditions for subsequent installation.
