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 -”

The Railroad Car The essentials: Car body Bolsters Suspension System Bearings Wheels Show example on board Photo: Cliff Cessna

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

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

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 Show example on board

Suspension System Show example on board Armstrong Fig. 5-4

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) Show example on board

The Train – Putting It Together The essentials: Power (previously discussed) Couplers Draft gear Braking system Show example on board

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 Show example on board Armstrong Fig. 6-1.

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. Show example on board Armstrong Fig. 6-2

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 Show example on board

Braking System Comprised of: Brake pipe (connected by hoses between cars) ABDX valve (triple valve) Auxiliary reservoir Emergency reservoir Brake cylinder Show example on board

Braking System Brake pipe and system charged with air to 70-90 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 Show example on board

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 Show example on board From: www.translationdictionary.com

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 Show example on board

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 Show example on board

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) Show example on board

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 Show example on board

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) Show example on board

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 Show example on board

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---------------- Show example on board

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 Show example on board

Questions? Show example on board Crash of Train 173, the Federal Express, January 14, 1953. From: wikipedia.org