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Name the 5 parts that constitute a rail?
- Running surface
- Rail head
Name the two types of rail assembly?
- Long welded rails - smoother and absorbs more shocks. Found in all ET running tunnels and most of the concession.
- Mechanical fish plate - two rails held together by two metal plates. Not as smooth and need copper connectors fitted in ET concession to allow transfer of intermittent data.
What are the three tractive forces that the track can tolerate?
- Vertical - essentially due to rolling stock
- Longitudinal - happens during acceleration and deceleration
- Transversal - Caused by the rolling stock and centrifugal forces of trains traveling on curved parts of track.
How do you counter a vertical stress?
Theses stresses are spread over the largest possible surface of ballast or onto concrete via the rails and sleepers.
How do you counter longitudinal stresses?
A unified rail-anchoring device - a spring which functions by squeezing the base of the rail and transfer the force into the sleeper. This in turn transfers the stresses onto the ballast and concrete slab.
How do you counter transversal stresses?
- Cant -Positioning the outer rail higher than the lower rail thus partially compensating centrifugal forces.
- Speed restrictions on curved sections of track.
- Guard rails in the inside of the track to keep the rails tight.
What is a DWD?
Derailed wheel and dragging parts detector, found at 3.5km inside the end of each running tunnel and 3.5km either side of crossovers. Metal loops that sit at rail height and emit an electric signal if disturbed.
What is HBD and DFS?
Hot box detector and seized brake detector. Detects seized brake or axle. Situated in boxes near to and at level of the rails. Uses infrared beams to detect a change in heat.
What is the role of the track?
To support and guide the rolling stock
What are the constituent parts of the track?
- Intermediary elements i.e. ballast, sleepers and the anti-deformation systems
What is the role of a set of points?
- either to allow railway movements to advance from one track to another or onto a track which crosses another
- Or to prevent railway movements from approaching a mainline or passing a set point.
What is a fouling point?
A white sleeper placed on the inside rails of the frog (crossing). The point at which you must not stop a train past as you will come into another lines gauge.
What is facing the points and trailing the points?
- Facing the points is when you are at the base of the points running toes to heel.
- Trailing points is facing towards converging tracks when, it being previously correctly set for the running track, it runs from the heel of the switch blades to the toe.
What are trailable and non-trailable points?
- Trailable are points that can be approached via the heel regardless of if they have been set in the correct running direction.
- Non-trailable points must not be approached form the heel except when they have been previously correctly set for the running track.
What are the tree types of track found on the ET concession?
- Main track- concession track fitted with cab signalling equipment, used for railways movements in the tunnels and terminals
- Secondary tracks - tracks within the terminal that are not fitted with cab signally system, normally reserved for non-passenger train movements.
- Emergency sidings - these are tracks directly accessible from the tunnel exist in the event of an emergency.
What makes up a set of points?
- Fouling point
- Frog (crossing)
- Check rails
- Switch toes
- Switch blades
- Stretcher bars
- Control device
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