Alert !!!!/ Toad Air Brake Tn rally

[Orren Zook]

Thank you.

Now explain the escaping air sound when the brakes were not being applied.

From the treadle the air flow, when the treadle is operated goes to the relay valve and then to the respective brakes. There is no air flow in the system until and unless the treadle is operated. Or am I mistaken?

You are correct Jon, air from the foot valve goes to the service port of the relay valve which causes application of tank pressure via the delivery port to the spring brake assembly. There is no air to the service side of the brake chamber if the pedal is not depressed - then it is applied in a corresponding amount with the distance pedal of travel.