CHAPTER 6

THE TRAIN

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

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.

Braking

Braking (continued)

·Air Brakes

·Dynamic Brakes

·Independent Brakes

Braking System

• Comprised of:

-Brake pipe (connected by hoses between cars)

-ABDX valve (triple valve)

-Auxiliary reservoir

-Emergency reservoir

-Brake cylinder

• Fail-Safe System

Braking System (continued)

• 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

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

• Slack Action

EOT

• End-of-Train (EOT) device monitors brake pressure at the end of the train and train movement and radios information to locomotive cab

• If equipped with two-way communications, can be used to apply brakes from rear of train

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

• Train Dynamics

• L/V Ratio

• Train-Dynamics Analysis-Simulators-Cab Displays

Vehicle/Track Dynamics

– Cab Displays

Positive Train Control

Positive Train Control

Positive Train Control