Bolts & Nuts in the Railway Tracks

What is rail track? What are the different types and sizes of bolts and nuts required in Rail track assembly?

A rail track consists of two parallel steel rails secured to sleepers (or ties) on which trains run. The main components of a rail track are:

1. Rails: Long steel bars laid in pairs, which provide a smooth surface for train wheels.
2. Sleepers (Ties): Transverse supports maintaining the spacing of the rails and transfer loads to the track ballast.
3. Fastenings: Bolts, nuts, clips, and other devices to hold the rails to the sleepers.
4. Ballast: Crushed stones under the sleepers for load distribution, drainage, and stability.
5. Fishplates and Rail Joints: Components used to join rail sections together.

Types and Sizes of Bolts and Nuts in Rail Track Assembly

In rail track assembly, bolts and nuts are crucial for fastening the rails to sleepers, connecting rail joints, and securing various components. Here are the main types used:

1. Fish Bolt and Nut
   • Purpose: Used to join two rail sections together via fishplates (or joint bars).
   • Common Sizes: Fish bolts usually come in diameters of 16mm, 20mm, or 25mm, and lengths range from 110mm to 165mm, depending on the rail size.
   • Shape: These bolts typically have an oval neck, which prevents rotation when tightening the nut.
2. Track Bolts and Nuts
   • Purpose: Secure the rail to base plates or other fastening systems.
   • Common Sizes: Diameter can range from 16mm to 25mm, with lengths between 130mm and 150mm, based on the rail’s weight and track structure.
3. Anchor Bolts
   • Purpose: Used for securing rails to concrete sleepers or base plates, helping prevent rail movement.
   • Common Sizes: Usually range in diameters from 19mm to 25mm.
4. Clip Bolts and Nuts (Elastic Rail Clips)
   • Purpose: Attach elastic rail clips to fasten rails to concrete sleepers.
   • Common Sizes: Generally have a diameter of 18mm or 20mm, with lengths adjusted based on sleeper type.
5. Shoulder Bolts
   • Purpose: Secure rail shoulders to the sleepers, primarily for use with elastic fastening systems.
   • Common Sizes: Vary according to the rail profile, with typical diameters of 22mm to 25mm.
6. Switch Bolts and Nuts
   • Purpose: Used in turnouts and rail switches to hold movable rails in place.
   • Common Sizes: Typically range from 22mm to 25mm in diameter.

The appropriate selection of bolts and nuts depends on rail weight, track type (mainline, sidetrack, etc.), and the type of sleeper used (wooden, concrete, or steel).

 

What are the sizes of different Fish bolt and nut?

Fish bolts and nuts are used to join two rail sections together with the help of fishplates (joint bars). The sizes of fish bolts and nuts vary depending on the rail size, the type of track, and the specific requirements of the railway. Here are the common sizes used in rail track assembly:

Fish Bolt Sizes

The size of fish bolts typically varies based on the rail weight and the rail section. The most common sizes are:

1. Diameter
   • Fish bolts usually come in diameters of 16mm, 20mm, 22mm, or 25mm.
   • The diameter chosen is based on the rail’s weight and type; heavier rails usually require bolts with larger diameters.
2. Length
   • The length of fish bolts generally ranges from 100mm to 165mm. Common lengths include:
     • 130mm
     • 140mm
     • 150mm
     • 165mm

The length is selected based on the rail’s height and the thickness of the fishplates used.

Fish Nut Sizes

The nuts used with fish bolts are typically hexagonal in shape and come in various sizes, corresponding to the bolt diameters:

1. Standard Sizes
   • The nut sizes are matched to the fish bolt diameters, typically ranging from M16, M20, M22, to M24.
   • For a 16mm diameter bolt, an M16 nut is used.
   • For a 20mm diameter bolt, an M20 nut is used, and so on.
2. Thread Types
   • Fish bolts generally have coarse threads (standard metric or imperial thread pitch), which allow for strong clamping force.

Selection Criteria

The selection of fish bolt and nut sizes depends on factors such as:

• Rail section and weight (e.g., 60 kg/m, 52 kg/m)
• Fishplate thickness and type
• Type of railway (mainline, sideline, heavy-haul, etc.)

Typical Combinations for Various Rails

• For 52 kg/m rails: Fish bolts with a diameter of 20mm and a length of 130mm to 150mm are commonly used.
• For 60 kg/m rails: Fish bolts with a diameter of 22mm or 25mm and a length of 140mm to 165mm are typically used.

The correct bolt size ensures proper alignment and secure fastening of the rails, minimizing rail movement and ensuring track safety.

 

What are the sizes of different Track bolts and nuts?

Track bolts and nuts are used to secure rails to base plates, splice bars, or other track components. The sizes of track bolts and nuts vary based on the type of rail, track structure, and requirements of the railway. Here are the common sizes for track bolts and nuts:

Track Bolt Sizes

1. Diameter
   • Track bolts typically come in diameters of 16mm, 19mm, 22mm, 24mm, and 25mm.
   • The diameter selected depends on the rail’s weight, type of sleeper (wooden, concrete, or steel), and the fastening system used.
2. Length
   • The length of track bolts generally ranges from 130mm to 170mm.
   • Common lengths include:
     • 130mm
     • 140mm
     • 150mm
     • 160mm
     • 170mm

The length is chosen based on the height of the rail and the thickness of the fastening components (such as the base plates).

1. Thread Types
   • Track bolts usually have coarse threads, which are preferred for securing components and providing a strong clamping force.
   • Threads can be either metric or imperial, depending on the railway standards.

Track Nut Sizes

1. Standard Sizes
   • The nuts used with track bolts are typically hexagonal and matched to the bolt diameter.
   • Common nut sizes correspond to the bolt diameters, such as:
     • M16 nut for 16mm bolts
     • M19 nut for 19mm bolts
     • M22 nut for 22mm bolts
     • M24 nut for 24mm bolts
     • M25 nut for 25mm bolts
2. Threaded Pitch
   • Track nuts have a thread pitch that matches the corresponding track bolt. The pitch is typically coarse to ensure the nuts stay secure under heavy vibrations.

Common Track Bolt and Nut Combinations for Various Rail Types

• For light rails (30-40 kg/m): Typically, 16mm to 19mm diameter bolts with lengths ranging from 130mm to 150mm are used.
• For medium rails (50-60 kg/m): Bolts with a diameter of 22mm or 24mm and lengths between 140mm and 160mm are commonly used.
• For heavy rails (above 60 kg/m): Bolts with a diameter of 24mm to 25mm and lengths of 150mm to 170mm are used to handle the higher loads.

Special Types of Track Bolts

• Square-Head Track Bolts: Often used in joint bars or fishplates, square-headed bolts prevent rotation during installation.
• Hex-Head Track Bolts: Commonly used for direct rail-to-sleeper fastenings.
• Hook Bolts (HS Bolts): Used for fastening base plates to concrete sleepers.

The right size and type of track bolts and nuts ensure the stability and safety of the rail track by securely fastening the rails in place and minimizing track movement.

 

What are the sizes of different Anchor bolts?

Anchor bolts are used in rail track assembly to secure the rails to concrete sleepers or base plates, preventing rail movement and ensuring stability. The sizes of anchor bolts vary depending on the rail type, fastening system, and sleeper configuration. Here are the common sizes of anchor bolts used in railway tracks:

Anchor Bolt Sizes

1. Diameter
   • The diameter of anchor bolts typically ranges from 16mm to 32mm, with common sizes being:
     • 16mm
     • 19mm
     • 22mm
     • 24mm
     • 25mm
     • 28mm
     • 30mm
     • 32mm
   • The diameter selection depends on the rail weight, fastening system, and type of sleeper. Heavier and higher-speed rail applications typically require larger diameters for added strength.
2. Length
   • Anchor bolt lengths can range from 150mm to 600mm, depending on the thickness of the sleeper and the depth of anchorage needed. Common lengths include:
     • 150mm
     • 200mm
     • 250mm
     • 300mm
     • 350mm
     • 400mm
     • 500mm
     • 600mm
   • The length is chosen based on the type of sleeper (concrete, wooden, or steel) and the required depth of embedment for secure anchoring.
3. Thread Types
   • Anchor bolts usually have coarse threads to ensure a strong grip within the fastening system. The thread pitch and length are selected to match the nut and washer assembly used with the bolts.
   • Metric and imperial thread standards can be used, depending on the regional railway specifications.

Types of Anchor Bolts

1. L-Shaped Anchor Bolts
   • Feature an “L” shape to prevent the bolt from pulling out of the concrete. Commonly used in concrete sleepers.
   • Sizes range from 19mm to 25mm in diameter and 200mm to 400mm in length.
2. J-Bolts
   • Shaped like a “J” to provide a secure hold within concrete.
   • Typically range in diameter from 16mm to 25mm, with lengths from 150mm to 350mm.
3. Straight Anchor Bolts
   • Straight bolts with threads at one end, used for base plates or other applications where a strong anchoring force is needed.
   • Available in larger sizes, such as 24mm to 32mm in diameter and 400mm to 600mm in length.
4. Wedge Anchor Bolts
   • Used for securing components to concrete surfaces, featuring an expanding wedge mechanism.
   • Commonly, it range from 16mm to 22mm in diameter.

Selection Criteria

The choice of anchor bolt size depends on factors like:

• Rail weight and track gauge: Heavier rails require larger bolts for secure fastening.
• Sleeper type: Concrete sleepers may require longer and larger-diameter bolts for secure embedding.
• Fastening system: The type of rail clip or other fastening mechanisms used will influence the bolt’s diameter and length.

Correct sizing of anchor bolts is critical for the durability and safety of the rail track, ensuring proper load distribution and resistance to vibration and movement.

Image: Straight Anchor bolt

 

What are the sizes of different Clip bolts and nuts for Elastic rail clips?

Clip bolts and nuts are used in conjunction with elastic rail clips to secure rails to concrete sleepers or base plates. They play a critical role in fastening the rails, providing flexibility, and absorbing the stresses from train movement. The sizes of clip bolts and nuts vary based on the rail fastening system and rail type. Here are the common sizes used for clip bolts and nuts in rail track assembly:

Clip Bolt Sizes for Elastic Rail Clips

1. Diameter
   • The diameter of clip bolts used with elastic rail clips typically ranges from 16mm to 25mm. Common sizes include:
     • 16mm
     • 18mm
     • 20mm
     • 22mm
     • 24mm
     • 25mm

The diameter selection depends on the type of rail, the fastening system, and the load requirements. Heavier and higher-speed rail applications often use bolts with larger diameters.

1. Length
   • Clip bolt lengths generally range from 100mm to 170mm, depending on the thickness of the sleeper or base plate and the height of the rail. Common lengths include:
     • 100mm
     • 120mm
     • 130mm
     • 140mm
     • 150mm
     • 160mm
     • 170mm

The length is chosen based on the thickness of the sleeper, the clip configuration, and the required tightening depth.

1. Thread Type
   • Clip bolts usually have coarse threads to ensure a secure fit and strong clamping force. The thread pitch is selected to match the fastening system, ensuring proper tightening and resistance to loosening due to vibrations.

Clip Nut Sizes

1. Standard Nut Sizes
   • The nuts used with clip bolts are typically hexagonal and matched to the bolt diameter. The corresponding sizes for the nuts are:
     • M16 nut for 16mm bolts
     • M18 nut for 18mm bolts
     • M20 nut for 20mm bolts
     • M22 nut for 22mm bolts
     • M24 nut for 24mm bolts
     • M25 nut for 25mm bolts
2. Threaded Pitch
   • The nuts are threaded to match the bolts, usually with a coarse thread for a secure hold. The thread pitch is specified according to the rail fastening system used.

Types of Clip Bolts Used in Elastic Rail Clip Fastening Systems

1. Hook Bolts
   • These bolts feature a hooked shape, allowing them to engage directly with the rail clip and base plate, providing a firm hold. Common sizes range from 18mm to 24mm in diameter.
2. T-Bolts
   • Designed to fit into a specific slot in the rail base plate, T-bolts provide a strong connection for elastic rail clips. Typical sizes are 20mm to 25mm in diameter.
3. Threaded Studs
   • Used in some elastic rail clip systems, threaded studs are anchored into the concrete sleeper, with nuts securing the rail clips. Sizes usually range from 18mm to 22mm.

Selection Criteria

The choice of clip bolt and nut size depends on factors such as:

• Rail weight and track type: Heavier rails require larger clip bolts for secure fastening.
• Sleeper material: Concrete sleepers often require longer bolts due to their thickness.
• Elastic rail clip type: Different clip designs may necessitate specific bolt configurations.

Correct sizing of clip bolts and nuts ensures the reliable fastening of the rail to the sleeper, helping maintain track stability and alignment under dynamic loads.

Image: T-bolt for Elastic Rail Clip

 

What are the sizes of different Shoulder bolts for Rail track?

Shoulder bolts are used in rail track fastening systems to secure rail shoulders to the sleepers. The rail shoulder provides a point of attachment for elastic rail clips, which hold the rail in place. Shoulder bolts are essential for ensuring the stability and alignment of the rail track, especially in concrete sleeper applications.

Sizes of Shoulder Bolts for Rail Tracks

1. Diameter
   • Shoulder bolts typically come in diameters ranging from 18mm to 25mm. The most common sizes include:
     • 18mm
     • 20mm
     • 22mm
     • 24mm
     • 25mm

The appropriate diameter is chosen based on the type of rail fastening system, the rail weight, and the requirements of the track.

1. Length
   • The length of shoulder bolts usually ranges from 130mm to 250mm, depending on the thickness of the sleeper and the specific rail fastening system. Common lengths include:
     • 130mm
     • 150mm
     • 170mm
     • 200mm
     • 220mm
     • 250mm

Longer shoulder bolts may be used for thicker concrete sleepers or more complex fastening configurations.

1. Thread Types
   • Shoulder bolts typically have coarse threads to ensure a strong grip and to resist loosening under the dynamic loading conditions of rail tracks.
   • Thread pitch and length are selected to match the fastening system used, with threads generally limited to the end portion of the bolt.

Types of Shoulder Bolts Used in Rail Track Assembly

1. Standard Shoulder Bolts
   • These bolts have a smooth, unthreaded shoulder section that fits snugly into the rail shoulder, with threads at the end for securing nuts. They are commonly used in fastening elastic clips to rail shoulders on concrete sleepers.
   • Sizes typically range from 18mm to 24mm in diameter, with lengths of 130mm to 200mm.
2. Shoulder Bolts with Washers
   • Some shoulder bolts come with attached washers to distribute the load more evenly and prevent damage to the sleeper or fastening components.
   • Common diameters are 20mm to 25mm, with lengths of 150mm to 220mm.
3. Heavy-Duty Shoulder Bolts
   • Designed for heavy rail applications, these bolts are used in tracks that experience high loads or heavy traffic. They are often larger, with diameters of 24mm to 25mm and lengths up to 250mm.

Selection Criteria

The appropriate size of shoulder bolts for rail track applications depends on factors such as:

• Rail weight and size: Heavier rails require larger shoulder bolts for secure fastening.
• Sleeper type and thickness: Concrete sleepers may require longer shoulder bolts.
• Rail fastening system: Different rail fastening designs (e.g., elastic rail clips, direct fastening) may have specific bolt size requirements.

Choosing the correct shoulder bolt size ensures that the rail track remains stable under dynamic loads and that the rail fastening system functions effectively, maintaining the proper alignment and securing the rails.

 

What are the sizes of different Switch bolts and nuts for rail track?

Switch bolts and nuts are used in railway turnouts, switches, and crossings to secure the movable rails, guard rails, or switch points in place. These bolts are essential for the alignment and operation of the switch mechanisms, ensuring that the movable sections of the track can be adjusted or locked securely. The sizes of switch bolts and nuts can vary based on the rail type, track requirements, and specific configurations of the turnout.

Sizes of Switch Bolts for Rail Tracks

1. Diameter
   • Switch bolts typically come in diameters ranging from 16mm to 25mm. Common sizes include:
     • 16mm
     • 19mm
     • 22mm
     • 24mm
     • 25mm

The diameter is chosen based on the type of turnout, rail section, and the specific load requirements of the track. Heavier or high-speed tracks may require larger diameters for additional strength.

1. Length
   • The length of switch bolts can range from 100mm to 300mm, depending on the rail’s height, the thickness of the fastening components, and the turnout’s design. Common lengths include:
     • 100mm
     • 120mm
     • 150mm
     • 180mm
     • 200mm
     • 250mm
     • 300mm

The appropriate length is selected based on the thickness of the rails and components to be fastened, ensuring proper clamping and secure fastening.

1. Thread Type
   • Switch bolts usually have coarse threads for a strong grip, providing resistance to loosening due to track vibrations and dynamic loads.
   • Threaded sections are typically at the end of the bolt, with a smooth section near the bolt head to allow for secure fastening and proper alignment.

Sizes of Switch Nuts

1. Standard Nut Sizes
   • The nuts used with switch bolts are typically hexagonal and matched to the bolt diameter. The corresponding nut sizes are:
     • M16 nut for 16mm bolts
     • M19 nut for 19mm bolts
     • M22 nut for 22mm bolts
     • M24 nut for 24mm bolts
     • M25 nut for 25mm bolts
2. Thread Pitch
   • The nuts are threaded to match the bolts, usually with a coarse thread for secure fastening. The pitch is selected to ensure proper tightening and resistance to loosening under vibration.

Types of Switch Bolts Used in Rail Track Turnouts

1. Standard Hex-Head Switch Bolts
   • These bolts are used to fasten switch components like stock rails, guard rails, and crossing rails. They have a hex head for easy tightening and come in sizes ranging from 16mm to 25mm in diameter.
2. Square-Head Switch Bolts
   • Square-headed switch bolts are sometimes used for turnouts, as the square head can provide better anti-rotation properties during tightening. Common sizes are 19mm to 24mm in diameter.
3. Clip Bolts for Switch Clips
   • Used in conjunction with switch clips for securing switch rails to the base plates. These bolts may range from 18mm to 22mm in diameter and have a length of 150mm to 250mm.
4. Heavy-Duty Switch Bolts
   • Designed for areas of the track where heavy loads or high-speed traffic occurs, requiring bolts with larger diameters (up to 25mm) and longer lengths (up to 300mm).

Selection Criteria

The selection of switch bolt and nut sizes is based on factors such as:

• Rail weight and turnout type: Heavier rails or specialized turnouts may require larger bolts for secure fastening.
• Thickness of switch and guard rails: Thicker components may require longer bolts for proper engagement.
• Traffic load and speed: High-speed or heavy-load tracks may necessitate larger and stronger bolts to withstand the forces.

Correct sizing of switch bolts and nuts ensures reliable operation of the track turnout and maintains alignment under dynamic loading conditions, contributing to the safety and performance of the railway.