Railway Vehicle Technology Flashcards
Vehicle Mass per seat
Examples for passenger transport
Air 250kg/seat Car. 300 Bus. 250 Local train. 500-600 Regional train 600-800 High speed train (Japan). 500-600 High speed train (eu) 900-1200
6 reasons why rail vehicles are often heavy
High passenger safety High operational safety Long life Good comfort Standardized components Long tradition
6 consequences of higher vehicle mass
More track damage More wheel and brake damage More maintenance of wheels and brakes Poorer acceleration and Retardation Alternatively upgrading of traction and braking systems Increased energy usage
4 reasons why rail vehicle can’t be much lighter
Powered wheelsets may slip excessively
Light vehicles might overturn in strong crosswinds
Very light vehicles might derail at high longitudinal forces between vehicles
Very light vehicles might not short-circuit the tracks signaling system
Mass dependence of energy usage
RB, G, Acc, R
Metro. 80%
Regional 43%
High speed 19%
Cost comparison:
Mass car x2
Mass train /2
Car +5€/100pkm
Train -0.65€/100pkm
Adhesion utilization
α = Fα / mα g
Probability of 0.22 available adhesion
0.03
why is utilized adhesion always lower than wheel rail friction?
- utilized adhesion cannot be lower than available adhesion
- lateral forces and motions “consume” part of the friction
- track irregularities prevent vertical force from being constant
Examples of available adhesion levels in practice
Traction: V<50. 0.25 V>50. 0.2 At higher speeds. 0.1-0.2 At leaf fall. 0.03-0.05
Braking (safety related)
V< 200. 0.1-0.15
V>200. 0.05-0.1
At lead fall. 0.03-0.05
Phenomena to be considered for vehicle gauging
Curving behavior vehicle movements: -lat displ wheelset/track -lat displ 1. 2. suspesion -lat displ sway/tilt -vert displ wheelset/track -vert displ 1. 2. suspensioin -vert displ sway/tilt -displacement due to asymmetry -space for track irregularities (3D) -margins for others (wind, future changes, uncertanties)
Formula for equivalent mass
me = m+Je/r²
definition structure gauge or obstacle gauge
the space to be kept free of fixed installations
sizing is based on a standardised reference vehicle
definition loading gauge or construction gauge
loading gauge defines the cross section of the reference vehicle
construction gauge, when loading gauge restricted by vehicle itself
Formula for curving overthrow
Δi: a²+a_p²/8R
a bogie distance
a_p wheelset distance
Curve widening of structure gauge
EU vs SE
SE very high
Eu very low
Running resistance
Dm mechanical
Dc additional in curves
Da aerodynamic drag
Ds gradient resistance
Davis equation
Dm Da = A Bv Cv^2
Aerodynamic drag
ρ/2 A Cd v^2 +
(q +Co Lt) v
Gradient resistance
m g G
Static gauge
Implies that the vehicle has low sway flexibility/stiff suspension
Only considers pure lateral and vertical maximum displacements of suspension
Kinematic reference gauge
Includes most vehicle movements- excluding movements that are different on different railway networks (variations in cant deficiency)
Used in interoperable European vehicles
UIC 505
Dynamic envelope
All tolerances and movements, defined just inside the limit structure gauge
Well defined division between vehicle and infrastructure
Comparative gauging
If gauge generally undefined
Comparator vehicle with proven history is used
Stiff-soft wheelset steering
Stiff: good on straight
Curves: High lateral track forces, high running resistance, large wear on wheel and track
Soft, good on curve
Risk for hunting on straight
Weight difference empty loaded examples
El loco. +1%
Coaches long distance 20
Coaches suburban 70
Freight 500
Rubber springs
Pro: different geometries
Built in damping
Low weight small volume
Inexpensive
Con: high dynamic stiffness
Stiffness increase at low temperature
Crew page in springs over long term
Air springs
Pro: isolates noise/vibes Little vertical space Automatic floor leveling Low stiffness for large volume Stiffness increases with more load
Con: complicated
Expensive
Orifice damping can result in too high stiffness
Coil springs
Pro: Little lateral space
Easy to get desired stiffness
Cons: large vertical space
Large height difference for load variations
Horizontal displacement limited
No damping
Kinds of dampers
Hydraulic
Friction
Orifice
Connection to bogie car body
Directly suspended
Plate
Traction rod
Jacobs bogies
Pro: less bogies
Reduced weight, a drag, energy
Lower floor level
Wider/comfortabler gangways
Con: high axle load
Shorter car bodies
Difficult to uncouple
Sl Subway semi trailer
Pros and cons similar to jacobsbogies
Inboard bearing bogie
Reduced: weight
Umsprung mass
Space required
Life cycle cost
Running gear with independent rotating wheels
Pro: Low floor level
No hunting motion
Good in R<150m
Con: no self steering
Higher flange climbing risk
Difficult to drive wheels evenly
Acceleration distance
V^2/2a
Weight difference empty loaded examples
El loco. +1%
Coaches long distance 20
Coaches suburban 70
Freight 500
Rubber springs
Pro: different geometries
Built in damping
Low weight small volume
Inexpensive
Con: high dynamic stiffness
Stiffness increase at low temperature
Crew page in springs over long term
Air springs
Pro: isolates noise/vibes Little vertical space Automatic floor leveling Low stiffness for large volume Stiffness increases with more load
Con: complicated
Expensive
Orifice damping can result in too high stiffness
Coil springs
Pro: Little lateral space
Easy to get desired stiffness
Cons: large vertical space
Large height difference for load variations
Horizontal displacement limited
No damping
Kinds of dampers
Hydraulic
Friction
Orifice
Connection to bogie car body
Directly suspended
Plate
Traction rod
Jacobs bogies
Pro: less bogies
Reduced weight, a drag, energy
Lower floor level
Wider/comfortabler gangways
Con: high axle load
Shorter car bodies
Difficult to uncouple
Sl Subway semi trailer
Pros and cons similar to jacobsbogies
Inboard bearing bogie
Reduced: weight
Umsprung mass
Space required
Life cycle cost
Running gear with independent rotating wheels
Pro: Low floor level
No hunting motion
Good in R<150m
Con: no self steering
Higher flange climbing risk
Difficult to drive wheels evenly
Acceleration distance
V^2/2a
Block braking
Pro: simple, cheap, light
Cleans wheel tread
Con: energy dissipated by wheels
Tread wear
Noise
Disc brakes
Pro: thermal energy in deprecate discs
Speed independent
Long life, low noise, no wheel wear
Con: expensive, heavy,
+unsprung mass
Special axles
Magnet rail braking
Pro: weight independent
Cleans rails
Con: expensive, heavy
Needs el power
Bad at high speed
Wear
Double deck
Pro: 30-40% more seats
10-20% lower cost
Suitable for uic
Con: level differences High center of gravity Side wind sensitivity Narrow profile on top level Low ceiling height
Extra wide trains
Pro: 25-35% more seats
15-20% lower costs
Tilting possible
Con: not suitable for uic
Middle seat not popular
Passenger flow
Lane:
1: 75-90cm, 20-30p/min
1. 5: 120-130, 30-45
2: 140-160, 40-60
Local vs long distance
Local has:
Double capacity per wagon
Halv the stopping time
Needs 4-6 lanes instead 1-2
Name of safety related place at each end of a train
Survival space
Car body materials
Carbon steel
Stainless steel
Aluminium
Composites and sandwich structures
Car body definition
Load carrying structure
Outer equipment
Interior and comfort systems
