1. CE 515 Railroad Engineering
The Railroad Car and the Train
Source: Armstrong Ch 5 & 6, AREMA Ch. 2.5
“Transportation exists to conquer space and time -”

2. The Railroad Car The essentials: Car body Bolsters Suspension System
Bearings
Wheels
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Photo: Cliff Cessna

3. Car Body This is the main part of the car that carries the cargo
Many different types to carry different commodities
Photo: Cliff Cessna

4. Bolsters Car body rests on center plate on bolster
Distribute weight evenly to springs on each side
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Armstrong Fig. 5-3

5. Suspension System Heavy-duty springs are used for suspension
Standard springs used with varying amounts of inner coils for heavier loads
Springs compress 2½ to 4¼ inches when under load; more than this would affect couplings
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6. Suspension System
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Armstrong Fig. 5-4

7. Bearings and Wheels
Springs are supported by a frame which connects directly to the axles
Friction bearings used until 1963
Roller bearings replaced the friction bearings
Reduced maintenance
Required for interchange service to other railroads
Wheels typically 33 or 36 in., based on weight (28 in. for some tall cars)
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8. The Train – Putting It Together
The essentials:
Power (previously discussed)
Couplers
Draft gear
Braking system
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9. Couplers
Federal Safety Appliance Act of 1893 required standardization for safety reasons
Link-and-pin required going between cars
Swinging-knuckle design chosen for standard
Two types: E and F
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Armstrong Fig. 6-1.

10. Draft Gear Used to cushion shock and strain on cars from movement
Friction in system absorbs energy
Most have a coupler travel of 5½ in., but some cars (mainly boxcars) have 9½ in. of give.
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Armstrong Fig. 6-2

11. Braking System
Most complex system on the train (and hardest to understand)
Originally developed by George Westinghouse in 1872 (Westinghouse Air Brake Company or WABCO)
Fail-safe system
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12. Braking System Comprised of:
Brake pipe (connected by hoses between cars)
ABDX valve (triple valve)
Auxiliary reservoir
Emergency reservoir
Brake cylinder
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13. Braking System
Brake pipe and system charged with air to psi (110 psi on passenger trains)
Once charged, all brake valves in “release” position
Some leakage will occur such that each successive car will have less pressure
This is called “brake pipe gradient” and must be less than 15 psi for entire train
End-of-Train (EOT) device monitors brake pressure at the end of the train and radios information to locomotive cab
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14. EOT/FRED Also called a FRED (Flashing Rear-End Device)
If equipped with two-way communications, can be used to apply brakes from rear of train
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From:

15. Applying Brakes Engineer reduces pressure in brake line
Brakes apply on car next to locomotive
Reduction in air pressure travels through train, one car to the next
Can take several seconds for “signal” to reach end of train
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16. Applying Brakes Assume train brake line has 70 psi
“Service application” – If the engineer makes a 10 psi application:
Brake line pressure reduced to 60 psi
10 psi of air flows from reservoir to brake cylinder
Reservoir is 2.5 times larger than cylinder
PV = nRT, so cylinder puts 25 psi on brakes
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17. Applying Brakes
“Full Service Application” – Engineer makes a 20 psi application
Brake line pressure reduced to 50 psi
20 psi x 2.5 = 50 psi in brake cylinder
Air pressure equalized, no further reductions possible (valve on each car holds pressure on brakes until brake line pumped back up above 50 psi)
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18. Other Trains Assuming brake line pressure of 90 psi
Full service application: 64.3 psi
Emergency application: 75 psi
Assuming brake line pressure of 110 psi
Full service application: 78.6 psi
Emergency application: 91.7 psi
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19. Emergency Application
Engineer hits Emergency Brake (70 psi)
Opens release valve on locomotive fully
Sudden release of air recognized by valve
Auxiliary and emergency reservoirs dumped
Multiplier is now 5x
Do some math…
Pressure equalizes at 58.3 psi (vs. 50 psi)
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20. Emergency Application
Video: Amtrak in Michigan
Train was traveling at 70 mph at time of impact
By my estimation on Google Maps, the stopping distance is about ½ mile
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21. New Ideas Distributed Power Units (DPUs)
Locomotives throughout train = Release points throughout train = Faster application
Assume 48 cars:
1 - L
½ - L * L
1/3 - L * L
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22. New Ideas Electronically Controlled Pneumatic (ECP)Brakes
Electronic signal activates brakes on each car nearly instantly (speed of light)
Flaw: Every car on the train must have wiring and electronic controls
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23. Questions? Show example on board
Crash of Train 173, the Federal Express, January 14, From: wikipedia.org