Which of the following types of track fittings are fixed with the help of tie bars and cotters?
Rail to cast iron sleepers
Understanding Railway Track Fittings
Railway tracks are made up of several components working together to provide a stable and safe path for trains. These components include rails, sleepers, ballast, and various fittings. Track fittings are essential elements used to connect the rails to the sleepers and to connect different sections of the rails to each other. Their main purpose is to hold the rails securely, maintain the correct gauge (distance between the rails), and allow for expansion or contraction due to temperature changes.
Fixation Methods in Railway Tracks
Different types of sleepers and track designs use different methods for fixing the rails. Let's look at the options provided:
- Rail to cast iron sleepers: Cast iron sleepers, particularly the pot type, often come in two separate units for each rail. These two units are held together at a fixed gauge using a tie bar. The rail is then fixed to the pot sleeper using various means, and importantly, the tie bar is connected to the pots and secured using cotters. This arrangement allows the tie bar and cotters to maintain the correct gauge between the two pot units and thus between the rails fixed to them.
- Rail to steel trough sleepers: Steel trough sleepers are usually made from a single piece of steel pressed into a trough shape. Rails are typically fixed to these sleepers using clips (like elastic rail clips - ERC) and bolts or other specialized fastening systems, not tie bars and cotters.
- Rail to rail: Connecting two sections of rail end-to-end is done using fish plates and bolts. Fish plates are metal bars bolted to the web of the rails on both sides. Tie bars and cotters are not used for this purpose.
- Rail to wooden sleepers: Wooden sleepers have been traditionally used and rails are fixed to them using various methods like dog spikes, screw spikes, or using chairs and keys (made of wood or metal) with bolts or spikes. Tie bars and cotters are not the standard fixation method for directly connecting rails to individual wooden sleepers.
Tie Bars and Cotters with Cast Iron Sleepers
The use of tie bars and cotters is a distinguishing feature of the fixation system for certain types of cast iron sleepers, especially the two-piece or pot type. The tie bar runs horizontally connecting the two pots (one under each rail). Cotters are wedge-shaped pins driven through slots to secure the tie bar ends to the pots. This system is crucial for maintaining the gauge between the rails, which is critical for safe train movement.
| Sleeper Type | Typical Fixation Method(s) | Use of Tie Bars & Cotters? |
|---|---|---|
| Cast Iron (Pot Type) | Keys, plates, tie bar with cotters (for gauge) | Yes (for gauge maintenance) |
| Steel Trough | Clips (e.g., ERC), bolts, keys | No |
| Wooden | Dog spikes, screw spikes, chairs & keys | No (not for direct rail fixation) |
Based on the typical fixation methods for different types of railway sleepers, the use of tie bars and cotters for maintaining the connection and gauge is characteristic of the system used for fixing rails to cast iron sleepers, particularly the pot or plate types where the sleepers for each rail are separate units linked by a tie bar.
Conclusion on Track Fittings
Therefore, among the given options, the track fittings that are fixed with the help of tie bars and cotters are those connecting the rail to cast iron sleepers (specifically the components that hold the cast iron sleeper units together at the correct gauge).
Revision Table: Key Track Components & Fixations
| Component | Purpose | Fixation Methods Discussed |
|---|---|---|
| Rails | Guide wheels, carry load | Fixed to sleepers, connected end-to-end |
| Sleepers | Support rails, transfer load to ballast, maintain gauge | Wooden, Steel Trough, Cast Iron (Pot/Plate) |
| Ballast | Provide support, drainage, elasticity | Underneath sleepers |
| Fish Plates & Bolts | Connect rail ends | Rail to rail connection |
| Tie Bar & Cotters | Maintain gauge for certain sleeper types | Connecting two-piece Cast Iron Sleepers |
| Spikes, Bolts, Clips, Keys | Fix rail to sleeper | Used with various sleeper types |
Additional Information: Railway Track Engineering Basics
The design and components of a railway track, also known as the permanent way, are crucial for safe and efficient train operations. The choice of sleeper type and fixation method depends on various factors including traffic load, speed, durability requirements, cost, and maintenance considerations. While cast iron sleepers with tie bars and cotters were common in the past, modern tracks often use pre-stressed concrete sleepers with elastic fastenings due to their longer life, better stability, and reduced maintenance needs.
Understanding how different track fittings like tie bars and cotters function is important for railway engineers and technicians involved in track construction and maintenance. The proper installation and maintenance of these fittings ensure the correct gauge and alignment of the track, preventing derailments and ensuring a smooth ride.
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