Railway Vehicle Guidance and Design
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Questions and Answers

What is primarily responsible for guiding a Railway vehicle?

  • The action of viscoelastic contact forces (correct)
  • The weight of the vehicle on the tracks
  • The flanges of the wheels
  • The design of the rail tracks

What happens if the cone angle of the wheelset is excessive?

  • The restoring force increases too much (correct)
  • The vehicle travels at a higher critical speed
  • The wheelset stability improves significantly
  • The wheelset loses contact with the rail

What is the recommended concity based on calculation and experience?

  • 1/20 or 0.05
  • 1/50 or 0.02
  • 1/40 or 0.025 (correct)
  • 1/30 or 0.033

How much contact is typically made between the wheelset and the rail within normal conditions?

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

What determines the trajectories of a TGV wheel set's contact with the rail?

<p>Track parameters and wheel inclination (B)</p> Signup and view all the answers

What is the maximum allowed angular amplitude of the oscillatory graph movements?

<p>10 minutes of arc (C)</p> Signup and view all the answers

What does the contact between rail and wheel not exceed under normal conditions?

<p>Clearance of 8 mm (B)</p> Signup and view all the answers

What critical factor affects the ideal situation of wheelset guiding?

<p>Critical speed (A)</p> Signup and view all the answers

What is the expected wavelength of hunting under normal conditions?

<p>30 M (B)</p> Signup and view all the answers

What is the effect of abnormal running surface wear on guiding?

<p>Negatively affects guiding (A)</p> Signup and view all the answers

What is the primary function of ballast in railway construction?

<p>To provide an elastic cushion between sleepers and the track formation (C)</p> Signup and view all the answers

What does cant deficiency refer to in railway terms?

<p>The required cant minus the actual cant provided (D)</p> Signup and view all the answers

Which term describes the longitudinal movement of rails?

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

What is meant by the term 'cross level' in railway terminology?

<p>The vertical height difference between the two rails at a point (C)</p> Signup and view all the answers

How is gauge defined in railway context?

<p>The distance between the rails (A)</p> Signup and view all the answers

What does a deep flange refer to?

<p>Flange depth more than 35 mm (A)</p> Signup and view all the answers

What is a 'switch' in terms of railway track components?

<p>An assembly of rails that connects two tracks (A)</p> Signup and view all the answers

Which term refers to the flat surface prepared for laying railway tracks?

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

What does 'sharp flange' indicate in railway terminology?

<p>Flange worn out with a radius less than 5 mm (D)</p> Signup and view all the answers

What is the role of flange force in railway movement?

<p>To generate force during wheel movement on tracks (C)</p> Signup and view all the answers

What occurs if the cone angle of a wheelset is insufficient?

<p>The wheelset bears against a flange not designed for that. (A)</p> Signup and view all the answers

How is the contact area between the wheelset and the track affected under normal conditions?

<p>It is confined to approximately 8 mm of contact. (C)</p> Signup and view all the answers

In regard to track parameters impacting wheelset guidance, which factor is NOT mentioned?

<p>Materials used in rail construction (B)</p> Signup and view all the answers

What defines the critical speed limit regarding wheelset guidance?

<p>The speed at which oscillatory movements become unstable. (C)</p> Signup and view all the answers

What is the hunting wavelength calculated to be under normal conditions?

<p>30 M (D)</p> Signup and view all the answers

What relationship do the oscillatory movements and hunting movements have?

<p>They are in harmony with each other. (C)</p> Signup and view all the answers

What is the consequence of excessive cone angles in regards to wheelsets?

<p>It generates short wave length restoring forces. (B)</p> Signup and view all the answers

What is NOT a characteristic of the cone angle's effect on wheelsets?

<p>Directly affects the gauge settings of the track. (B)</p> Signup and view all the answers

What is the maximum angular amplitude allowed for the oscillatory movements?

<p>2.5 M radius (D)</p> Signup and view all the answers

What is the primary purpose of the flanges in railway vehicles?

<p>To stop the vehicle from derailing during emergencies. (A)</p> Signup and view all the answers

What does cant deficiency specifically indicate in railway operations?

<p>The difference between required and actual cant on curves (B)</p> Signup and view all the answers

Which of the following best describes the term 'cross level' in railway systems?

<p>The vertical difference between left and right rails at a point (C)</p> Signup and view all the answers

What characteristic defines a 'deep flange' in rail terminology?

<p>Flange depth greater than 35 mm (D)</p> Signup and view all the answers

In railway terminology, what does the term 'gradient' refer to?

<p>The amount of slope in the longitudinal direction of tracks (A)</p> Signup and view all the answers

Which statement accurately defines 'point and crossing' in railway engineering?

<p>Components allowing a train to switch between tracks (A)</p> Signup and view all the answers

What is characterized by the hollow tyre exceeding 5 mm?

<p>A potential hazard for derailment (C)</p> Signup and view all the answers

What does the term 'flange force' refer to in railway contexts?

<p>The force created by a wheel's flange interacting with the rail (A)</p> Signup and view all the answers

Which option best describes the formation in railway construction?

<p>The flat surface prepared for laying tracks (D)</p> Signup and view all the answers

What does 'gauge' measure in the context of railways?

<p>The width between running edges of rails (D)</p> Signup and view all the answers

What condition does 'creep' describe in railway tracks?

<p>Longitudinal movement of rails within tracks (D)</p> Signup and view all the answers

Flashcards

Ballast

The material used as an elastic cushion between sleepers and the track foundation.

Cant or Superelevation

The difference in height between the outer and inner rails on a curve, designed to counteract the centrifugal force.

Cant deficiency

The difference between the ideal cant for a curve and the actual cant provided.

Cross level

The difference in vertical level between the left and right rails at a specific point on the track.

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Creep

The longitudinal movement of rails along the track caused by stresses.

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Deep flange

When the depth of the wheel flange exceeds 35 mm.

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Flange force

The force exerted by the wheel flange against the rail during movement.

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Formation

The flat surface of the earthwork prepared for laying tracks.

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Gauge

The distance between the inner edges of the two rails.

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Gradient or Grade

The amount of slope in a railway track, measured as a ratio.

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Visco elastic contact forces

The contact forces between the conical wheels and cylindrical rails, which guide railway vehicles.

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Cone Angle

The angle of the conical surfaces on the wheels, which influences the restoring force towards the center of the track.

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Hunting Movement

The sideways oscillations of a wheelset on the track, due to the conical shape of the wheels and the track's geometry.

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Cant

The difference in height between the inner and outer rails, which helps to counteract the centrifugal force of the train.

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Critical Speed

The maximum speed at which a train can safely operate without encountering instability due to hunting movement.

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Lateral Displacement

The deviation of the wheelset from its intended path.

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Rolling Line

The path traced by a wheelset on the track.

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Logic Oscillation

The tendency of a wheelset to oscillate vertically around its axis.

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Angular Amplitude

The maximum angular amplitude of the hunting movement of a wheelset.

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What is ballast?

The material used as an elastic cushion between the sleepers and the track foundation, providing support and absorbing vibrations.

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What is cant or superelevation?

The difference in height between the outer and inner rails on a curve, designed to counter the centrifugal force and keep the train on the track.

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What is cant deficiency?

The difference between the ideal cant for a curve and the actual cant provided, which can lead to instability at higher speeds.

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What is cross level?

The relative difference in vertical levels measured at the top of the left and right rails at a given point on the track.

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What is creep?

The longitudinal movement of rails in the track, caused by the forces exerted by the wheels.

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What is deep flange?

When the depth of the flange of a wheel exceeds 35 mm, which can cause problems with track gauge and derailments.

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What is flange force?

The force generated by the wheel flange during movement of the wheel along the track, which helps to guide the train.

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What is formation?

The flat surface of the earthwork prepared for laying tracks, providing a stable base for the railway.

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What is gauge?

The distance between the inside edges of the two rails, defining the width of the track.

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What is gradient or grade?

The amount of slope in the longitudinal direction of a railway track, which influences the speed and flow of trains.

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Study Notes

Railway Vehicle Guiding

  • Railway vehicle guidance is primarily ensured by visco-elastic contact forces between the conical wheel surfaces and cylindrical rail surfaces
  • Abnormal running surfaces, excessive or deficient cant, and switch/crossing work can disrupt this normal operation
  • Wheel flange contact acts as a secondary stop for exceptional circumstances
  • Insufficient cone angle leads to constant flange contact, a problem for the design
  • The guiding of a Railway vehicle is primarily affected by the visco-elastic forces between the wheel cones and rail cylinders
  • Flanges are just a secondary safeguard for unusual situations

Wheelset Restoring Force

  • Excessive restoring force is undesirable, especially in short-wave lengths (e.g., less than 20 meters)
  • The optimal concity, based on calculations and experience, is around 1/40 or 0.025
  • Hunting can result from improper concity, possibly from an oscillating behavior
  • Excessive restoring force is problematic, especially in short waves (e.g., less than 20 meters)
  • Restoring force relies heavily on the cone angle for smooth operation
  • Correct alignment creates smooth transitions without significant disturbances

Wheel-Rail Contact

  • Wheel-rail contact is confined to a small area of the total available clearance (typically 8 mm)
  • Rail and track parameters influence the movement of the wheel set
  • Wheel movements are not random and generally follow consistent patterns
  • Contact is largely confined to a narrow section, usually 8mm, of potential clearance
  • The wheel's movement on the rail is guided by track characteristics and is not arbitrary

Oscillatory Movement

  • Oscillatory movements are coordinated with hunting movements, showing a consistent pattern
  • Amplitude of these oscillatory movements doesn't exceed 2.5 meters (approximately 10 minutes of arc)
  • External factors affect the ideal situation created by the critical speed
  • Oscillations align with hunting movements and maintain a consistent pattern
  • The angular amplitude of these oscillations stays within 2.5 meters radius (about 10 minutes of arc)

Glossary

  • Ballast : Material used to cushion sleepers and the formation top.
  • Cant/Superelevation: Outer rail on curves is elevated above the inner rail to offset centrifugal forces.
  • Cant deficiency: Difference between the necessary cant for maximum speed and the actual cant provided.
  • Cross level: Relative difference in vertical levels between the left and right rails.
  • Creep: Longitudinal movement of rails.
  • Deep flange: When flange depth surpasses 35 mm
  • Flange force: Force generated by wheel flange during wheel movement.
  • Formation: Flat earthwork surface for track laying.
  • Gauge: Distance between the two running edges of the rails
  • Gradient: Amount of incline/decline of a railway track.
  • Hollow tyre: Tyre with depression exceeding 5 mm in depth.
  • Point & Crossing: System to allow trains to switch tracks
  • Running edge of the rail: Rail edge where wheel flange contacts the rail.
  • Sharp flange: Flange edge having a radius less than 5mm at its tip, suggesting wear
  • Stock rail: Rail on the main line that tongue rails connect to
  • Switch: Area where a train track changes direction, typically composed of stock and tongue rails
  • Tongue rail: Tapered rail that forms part of the switch assembly; one end is thicker ("Heel") and fixed, the other thinner ("Toe")
  • Thin flange: Flange thickness less than 16mm
  • Throw of switch: Distance tongue rails travel at the toe of the switch.
  • Twist: Rate of cross-level change per meter
  • Transition of curve: Smooth curve sections in railway lines to avoid abrupt changes in curve degree
  • Wheel base: Distance between adjacent axles on a bogie
  • Wheel gauge: Distance between inner edges of wheel flanges on an axle.

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Description

This quiz explores the dynamics of railway vehicle guidance, focusing on the roles of wheel-rail contact and restoring forces. It discusses critical design parameters and the impact of various track conditions on vehicle stability. Test your knowledge on optimal wheelset design and the significance of contact forces in railway systems.

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