Need Information for Flat Towing M931A2

[Mike929]

I think the sound you are hearing is air from the spring brakes. When you engage the parking brake, you release air from the spring brake chambers, causing the spring brakes to set. The sound you hear is that air as it is routed to the intake pipe. The regular service brakes take air pressure to apply but the spring brakes take air pressure to release. That is why you cannot drive off without first building air pressure. The sound it makes can vary from truck to truck, dying organ, someone stepping on a duck, a goose with a cold, etc.

There is also what is truly called the parking brake. that is a mechanical drum brake on the driveline. it works together with the spring brakes when you use the parking brake lever as long as the spring break override button is not in the override position.

Dang, I had hoped that I had a valve issue that needed to be addressed. Didn't know that was a standard shut down noise.

 

[ke5eua]

goose with a cold, etc.

Now Mike if had said a goose sound I would have known exactly what you were talking about. Never thought about comparing it to an organ though.

Where the parking brake is there is a little reid type switch, push that switch in and you will hear the sound and the parking brakes set.

We modified some of our trucks in Iraq to allow for setting the air brakes independent of the spring parking brake.