Railway Lag Screw for Wooden Sleeper

Railway lag screws, also known as sleeper screws or rail screws, are heavy-duty fasteners (often 6 inches long) used to secure rail base plates to wooden sleepers (ties), providing superior holding power compared to traditional spikes. These high-strength, often galvanized screws are installed into pre-bored holes, sometimes with plastic dowels, and come in square, hexagon, or double-head designs. 

Key Features and Specifications

• Types: Square head, hexagon (hex) head, double head (for Nabla clip systems), and dog screws.

• Dimensions: Typically manufactured in large sizes, with diameters ranging from 3/8 to 3/4 inches and lengths up to 20 inches. Common railroad sizes include 15/16 x 6-1/2 inches.

• Material & Treatment: Usually made of carbon steel (Q235, 35#, 45#) with galvanized, black oxide, or plain finishes to resist corrosion.

• Performance: Designed for high-tension, with some types required to withstand a 130 kN load without failure. 

Installation and Application

• Pre-drilling: While some timber screws are designed for self-tapping, railway sleeper screws usually require pre-bored holes in the wooden tie.

• Usage: Frequently used in the United States and Canada for fixing railway sleeper plates.

• Method: The screw is driven into the wood, sometimes using embedded plastic dowels to increase friction and holding power. 

Advantages

• High Strength: Superior fastening, reducing the frequency of maintenance compared to standard spikes.

• Superior Clamping: Provides better vertical clamping force for the rail, improving track stability.

• Easy Removal: Can be removed and re-installed, which is beneficial for maintenance.