Brake pipe pressure that must be present at the rear before beginning an Initial Terminal Air Brake Test (Class 1)?

• A. 60 psi
• B. 75 psi
• C. 90 psi
• D. 100 psi

Answer: (C)

This item hinges on having the air brake system fully charged so you can perform a reliable Initial Terminal Air Brake Test. The test requires starting with a brake pipe pressure that is high enough to ensure the entire train’s brake system is at service conditions and can respond correctly when brakes are applied and released, as well as when checking for leaks.

The correct minimum is 90 psi because it provides a solid, standard charge level at the rear that allows all brake valves and cylinders to operate predictably during the test. Starting at 90 psi ensures you’re testing under normal operating pressure, making brake application, release, and any leak checks meaningful and consistent.

Lower pressures, like 60 psi or 75 psi, wouldn’t guarantee the system is fully charged, which can lead to insufficient brake cylinder travel, unreliable readings, or false indications of leaks. A value higher than needed, such as 100 psi, isn’t required for this test and doesn’t add value beyond the standard 90 psi threshold.