Train Driver Braking Systems and Train Dynamics

Question 1

What is the primary braking system used on freight trains in the United States?

Accepted Answer

Pneumatic air brakes

Answer

Pneumatic air brakes, standardized by George Westinghouse, use compressed air to actuate brake cylinders and are the standard system for US freight trains.

Question 2

What happens when brake pipe pressure drops to zero on a train equipped with standard air brakes?

Accepted Answer

Emergency brakes apply automatically throughout the train

Answer

A complete loss of brake pipe pressure triggers an emergency brake application because the system is fail-safe — brakes apply when air pressure is lost.

Question 3

What is 'dynamic braking' on a diesel-electric locomotive?

Accepted Answer

Using traction motors as generators to create braking resistance

Answer

Dynamic braking converts traction motors into generators, dissipating kinetic energy as heat through resistor grids to slow the train without using friction brakes.

Question 4

What is the standard charged brake pipe pressure for freight trains in the United States?

Accepted Answer

90 psi

Answer

The standard brake pipe pressure for US freight trains is 90 psi when fully charged and brakes are released; passenger trains typically use 110 psi.

Question 5

What is a 'penalty brake application'?

Accepted Answer

An automatic emergency brake activation triggered by a safety system

Answer

A penalty brake application is an automatic emergency brake activation triggered by safety systems such as PTC, cab signal alerters, or overspeed detection.

Train Driver Practice Test

Train Driver Practice Test

Train Driver Braking Systems and Train Dynamics