Air Break Practice Test

Results

#1. In the air service circuit, there is a double (two-way) check valve connected to the primary and secondary service tanks. What does this valve do?

It prevents service tank air pressures from exceeding 150 psi.

It prevents air loss from the service tanks in the event of a supply circuit failure.

It prevents compounding of the service brakes and spring parking brakes.

It supplies compressed air from the service tank with the highest pressure.

The parking control valve (yellow button) in the dashboard is supplied with air from a double (two-way) check valve. This check valve supplies air (often called blended air) from the service tank with the highest pressure. If air pressure is lost in either the primary or secondary service circuit (but not both), the parking control (yellow button) will still work properly with air from the other circuit, and the spring parking brakes will stay released.