Question

Some vehicles have a modulating control valve. What does a modulating control valve do?

Accepted Answer

It enables you to put on the spring brakes gradually.

Answer

It enables you to increase or decrease the pressure of the air brakes.

Answer

It enables you to switch from the air braking system to the spring brake system.

Answer

It enables you to gradually decrease the pressure being sent to the trailer brakes.

Question 27 - Air Brakes Test Practice Test for the CDL