Railway Engineering Points and Crossings
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Questions and Answers

What should a pointsman ensure regarding hand points?

  • That the points are held down or locked. (correct)
  • That the points are fully automated.
  • That all points are labeled correctly.
  • That the points are adjusted regularly.

What can occur if the gauge is tight by 10 mm?

  • The wheel will certainly mount the nose. (correct)
  • The wheel will cause a derailment immediately.
  • The wheel will miss the edge of the nose.
  • The wheel will slow down significantly.

What impact does a high wing rail have on derailment risk?

  • It decreases the risk of derailment in both directions.
  • It has no impact on derailment risk.
  • It may cause a derailment in the trailing direction. (correct)
  • It solely assists in the leading direction.

Why is maintaining the correct check block clearance important?

<p>To allow for correct passage and avoid derailments. (C)</p> Signup and view all the answers

What should be avoided during the renewal of wing rails?

<p>Renewing wing rails without checking crossing conditions. (D)</p> Signup and view all the answers

Which of the following statements correctly defines the allowable condition of a tongue rail?

<p>A chipped/cracked length must be under 200 mm from the toe. (B), A chipped length can be over 10 mm but should not exceed 200 mm. (C)</p> Signup and view all the answers

What is the maximum allowable vertical wear for a tongue rail of 60 Kg?

<p>8 mm (C)</p> Signup and view all the answers

Which action is recommended if a tongue rail has developed a knife edged tip?

<p>Immediate replacement is suggested. (C)</p> Signup and view all the answers

What should be done when the tongue rail is badly twisted or bent?

<p>It should always be replaced. (B), Reconditioning by Jim crowing is sufficient. (D)</p> Signup and view all the answers

What is the purpose of providing steel packing at the toe of a switch?

<p>To adjust for slightly wide gauge. (D)</p> Signup and view all the answers

At what distance from the toe of the switch must the gauge be uniform?

<p>1000 mm (D)</p> Signup and view all the answers

Which condition is NOT considered under the classification of tongue rail being worn or damaged?

<p>Vertical wear exceeding 10 mm. (C)</p> Signup and view all the answers

For the 52 Kg and 90R tongue rails, what is the maximum lateral wear allowed?

<p>6 mm (D)</p> Signup and view all the answers

What should be done if the tongue rail is chipped to a depth of more than 10 mm over a continuous length of 10 mm?

<p>It should be classified as damaged and replaced. (C)</p> Signup and view all the answers

What is the correct maximum allowable vertical wear for 75R and 60R rails?

<p>3 mm (A)</p> Signup and view all the answers

What is a common consequence of an obstruction under the switches?

<p>The points will not close effectively. (D)</p> Signup and view all the answers

Which issue can arise from a bent rear point rod?

<p>Indication of points trailed through when not set. (C)</p> Signup and view all the answers

What role do loose heel bolts and poorly packed sleepers play in derailments?

<p>They allow the toe of switches to lift under passing wheels. (C)</p> Signup and view all the answers

What could be a sign of excessive wear leading to derailment?

<p>Switch head splitting longitudinally. (B)</p> Signup and view all the answers

How does the wear of stock rails affect switch performance?

<p>It leads to unexpected wheel contact with switch heads. (C)</p> Signup and view all the answers

How should the flange profile of a derailed vehicle's wheel be examined?

<p>By assessing any visible grease marks. (D)</p> Signup and view all the answers

What happens if the switch is worn excessively?

<p>It results in crushing and metal flow issues. (A)</p> Signup and view all the answers

What risk does forcing points open during shunting operations pose?

<p>It creates a danger for vehicles passing in the facing direction. (C)</p> Signup and view all the answers

What can be an indication that a point has been trailed through improperly?

<p>Visible distortion in point rod alignment. (D)</p> Signup and view all the answers

What maintenance issue can prevent proper switch setting?

<p>Inadequate heel bolt tightening. (A)</p> Signup and view all the answers

What is the role of the toe in a switch assembly?

<p>To provide a tapered edge that sets against the stock rail. (B)</p> Signup and view all the answers

What causes the toe of the tongue rail to jump upwards?

<p>Insufficient length of the tongue rail. (D)</p> Signup and view all the answers

What is the purpose of the stretcher bar in a switch assembly?

<p>To stabilize the stock rail and prevent jumping of the tongue rail. (D)</p> Signup and view all the answers

Which components are included in a crossing assembly?

<p>V rail, two wing rails, and two check rails. (B)</p> Signup and view all the answers

What can potentially cause a derailment in relation to the tongue rail?

<p>A gap between the tongue and stock rail. (C)</p> Signup and view all the answers

What aspect is crucial in the maintenance of points and crossings according to IRPWM?

<p>No junction fish plates at stock rail joints or heel of crossing. (D)</p> Signup and view all the answers

Which of the following parts is NOT included in a switch assembly?

<p>Crossing rails. (C)</p> Signup and view all the answers

What is the main function of the crossing assembly in points and crossings?

<p>To guide the movement of wheels and prevent derailment. (D)</p> Signup and view all the answers

What is indicated as a potential cause for badly worn wing rails or check rails?

<p>Wide gauge at the crossing (B)</p> Signup and view all the answers

How much vertical wear is allowed on a wing rail or the nose of a crossing?

<p>10 mm (B)</p> Signup and view all the answers

What should be recorded at stations during the inspection of turn-in curves on loops?

<p>Versines at 1.5 m intervals (B)</p> Signup and view all the answers

Which position should the obtuse crossings be laid in reference to the acute crossing?

<p>Square (B)</p> Signup and view all the answers

Who is responsible for the correct gauging of the switches?

<p>PWI (D)</p> Signup and view all the answers

What may cause derailments at switches?

<p>Gape in the points (C)</p> Signup and view all the answers

What is the distance between the throat and nose that must be maintained in obtuse crossings?

<p>Correctly (D)</p> Signup and view all the answers

When must any work involving the insertion or removal of points and crossings be authorized?

<p>Only by the Commissioner of Railway Safety (A)</p> Signup and view all the answers

What is a common cause for gaping points?

<p>Bent tongue rail (B)</p> Signup and view all the answers

What is the primary role of the SI in relation to points and crossings?

<p>To ensure proper fixing of interlocking apparatus (D)</p> Signup and view all the answers

Flashcards

Switch Assembly

A set of components that allow trains to switch tracks, consisting of two tongue rails and two stock rails.

Stock Rail

The outer track rail, forming part of the main line.

Tongue Rail

The movable rail that allows trains to change tracks, with a tapered edge that sets against the stock rail.

Heel of the Tongue Rail

The thicker end of the tongue rail.

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Toe of the Tongue Rail

The tapered edge of the tongue rail that contacts the stock rail to guide trains.

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Stretcher Bar

A device that prevents the tongue rail from jumping upwards, ensuring smooth track transitions.

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Crossing Assembly

It allows the passage of wheel flanges, guiding the train along the intended track.

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Points and Crossing Maintenance

An important aspect of railway maintenance, ensuring the safety and efficient operation of track switches.

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What can cause issues with points?

Obstruction on the track (like a stone) can prevent the points from setting correctly. But, on well-maintained tracks, mechanisms detect obstructions and ensure points close properly.

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What's a potential problem with interlocking equipment?

The loss of lever movement in the interlocking equipment, even with an obstruction, allows the lever to be pulled, potentially leading to a dangerous situation.

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What happens if points are forced open in the trailing direction?

Points can be forced open in the trailing direction during shunting operations. If not fixed, this can cause the switch to close improperly and put vehicles at risk in the facing direction.

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What sign might indicate points were incorrectly trailed?

A bent rear point rod can indicate that the points were trailed (opened against the intended direction) without being set correctly.

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What can cause the toe of the switch to lift?

Loose heel bolts and poorly packed sleepers under the heel chairs can cause the toe of the switch to lift under passing wheels, leading to derailment.

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How can excessive wear in switches cause derailment?

Excessive wear in switches can lead to splitting, which might cause a vehicle's wheels to bear on the switch head prematurely, causing metal to crush and potentially leading to derailment.

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What specifically needs to be considered in designing the 100 lbs 12 feet switch to prevent derailment?

The switch head is designed to be 5 mm lower than the stock rail at 450 mm from the toe. If the stock rail is worn and the switch side wear is not addressed, metal crushing will occur, preventing the switch from setting properly.

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What should be inspected after a derailment at facing points?

If a derailment occurs at facing points, inspect the flange profile of the derailed vehicle's wheels for sharpness. Grease marks on the vertical side of the flange indicate a likely defective wheel.

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How can a sharp flange profile contribute to derailment?

A sharp flange profile on a wheel can contribute to derailment at facing points.

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Gauge

The distance between the inside of the rails on a track.

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Crossing

An area where two tracks cross, facilitating movement between tracks and different directions.

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Wing Rail

The outer rail of a track at a curve, set higher than the inner rail to compensate for centrifugal force.

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Throat-Nose Distance

The distance between the throat (narrowest point) and the nose (widest point) of an obtuse crossing.

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Obtuse Crossing

A type of crossing where two tracks intersect at an angle other than 90 degrees.

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Diamond Crossing

A crossing with two tracks intersecting at 90 degrees, like a diamond pattern.

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Maximum Wear Limit

The maximum allowable wear on the wing rail or nose of the crossing.

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Curve Lead

Sections of track leading into a curve, gradually transitioning from straight to curved track.

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Cant

The vertical difference between the outer and inner rails at a curve, compensating for centrifugal force.

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Points and Crossings

The section of track where points and crossings are located, switching the train between tracks.

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Matching Rail Sections

At least one rail on either the points or crossing should be made from the same type of rail material as the Point and Crossing assembly, ensuring consistent strength and performance.

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Gauge Consistency in Point and Crossing

The distance between the rails should be consistent throughout the entire point and crossing, except for a slight slackening just before the toe of the switch, which allows space for the tongue rail.

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Replacement of Worn Rails

Worn or damaged rails, particularly the tongue rail and stock rail, should be replaced with new, serviceable ones to prevent derailments and ensure safe operation.

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Tongue Rail Wear Indicators (1)

A tongue rail is considered worn/damaged when it has chips or cracks extending over 200mm within 1000mm of the toe, or when it exhibits a thin, knife-edged tip over 100mm.

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Tongue Rail Wear Indicators (2)

A tongue rail is also considered worn/damaged if it is bent or twisted, creating a gap larger than 5mm between the tongue rail and the stock rail at the toe.

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Repairing Tongue Rail & Best Practice

While the tongue rail can be repaired by welding and bending, it is considered good practice to replace a tongue rail with a knife-edged tip, as it is prone to breaking at that point.

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Wear Limits for Tongue Rail

The wear of the tongue rail is measured below the top surface of the stock rail and should not exceed specific limits based on the rail weight (60Kg, 52Kg, 90R, 75R, 60R).

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Vertical Wear Limits for Tongue Rail

The vertical wear limit for a 60Kg rail is 8mm, while for 52Kg and 90R rails it is 5mm, and 3mm for 75R and 60R rails.

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Lateral Wear Limits for Tongue Rail

The lateral wear limit for a 60Kg rail is 8mm, while for 52Kg and 90R rails it is 6mm, and 5mm for 75R and 60R rails.

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Adjusting Wide Gauge at Toe of Switch

Slight widening of the gauge at the toe of the switch can be adjusted by inserting steel packing between the stock rail and the slide chair.

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Check Rail Clearance

The distance between the inner edge of the rail and the outer edge of the check rail, allowing for the safe passage of wheel flanges.

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High Wing Rail Derailment

The wear and tear on the crossing can make the wing rail too high, leading to potential derailment in the trailing direction.

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Wheel Mounting the Nose

This occurs when the gauge is tight by 10 mm, leading to the wheel hitting the edge of the crossing's nose.

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Tight Gauge

A tight gauge refers to when the distance between the rails is smaller than intended, pushing the wheel further out and increasing the chance of a derailment.

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Study Notes

Points and Crossings

  • Railway tracks are provided for receiving and dispatching trains
  • Trains need to cross other tracks to reach their destination
  • Points and crossings allow trains to change tracks
  • A set of points and crossing consists of switch assembly, crossing assembly, and lead rail joining switch and crossing assembly.

Switch Assembly

  • Consists of two tongue rails and two stock rails
  • Stock rail is part of the main rail
  • Tongue rail has a tapered edge (toe) that sets against the stock rail
  • Tapered toe prevents obstruction to wheel movement
  • Toe prevents jumping / rising due to weight on heel
  • If tongue rail is short, weight can cause toe to jump upwards
  • A stretcher bar is used to prevent jumping of the tongue rail
  • Sufficient room is needed for wheel flanges to pass through
  • Crossing assembly provides guidance for wheel movement

Crossing Assembly

  • Formed by joining V rail, two wing rails (left and right), and two check rails
  • Illustration of crossing assembly in provided

Important Aspects in Points and Crossing Maintenance

  • Junction fish plates should not be used at stock rail joints or at heel of crossing
  • Gauge should be uniform except near the toe of a switch
  • Worn/damaged stock and tongue rails should be replaced
  • Tongue rail assessment for wear (chipping/cracking of 200 mm within 1000 mm of toe; worn > 10mm over 10 mm length; or knife edge tip < 2 mm) triggers replacement
  • Vertical and lateral wear limits based on rail weight categories (60kg, 52/90R, 75/60R)
  • Gauge adjustments at crossings
  • Maintaining correct distances between throat and nose of obtuse crossings
  • Diamond crossings should be laid square to each other
  • Maximum vertical wear on wing rail/nose of crossing = 10mm

Derailments on Points and Crossings

  • Derailments occur at switches (points)
  • Gaping points or slightly bent tongue rails cause derailment
  • Obstructions (e.g., stones) can cause switch misalignment
  • Detection and immediate maintenance of defective points or crossings are crucial
  • Bent rear point rods indicate points not properly set
  • Loose heel bolts and poorly packed sleepers can cause toe lift -Excessive wear can cause longitudinal splitting
  • Excessive side wear can cause switch head crushing
  • Wheel flanges need to be assessed for sharpness (using grease marks) to identify defective wheels
  • Unmanned/unlocked hand-operated points are susceptible to opening slightly

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Related Documents

Points and Crossings PDF

Description

This quiz focuses on the components and functionality of points and crossings in railway engineering. It covers switch and crossing assemblies, highlighting their structures, such as tongue rails and stock rails, and their operational importance. Test your knowledge on how these components ensure safe and efficient train operations.

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