OT: Truck air brake problems

[Anonymous-0]

Hello,

Got a Mack dm-600 dump. Problem is when you push on brake pedel quick the emergency brake valve pops on, apply the emergency brakes. Truck has good air pressure and no apperant leaks, There are three lines on the emergency brake valve, and I have found the If I take the center small line off and cap the line, It won't do it and the brakes work fine. With that line off, and uncapped when you push on the brakes air blows out this line.

I traced the line to a valve under the cab mounted on the frame. It looks like a diaphram valve??? of some short??? With 2 or so larger lines on it??

This is the first air brake setup I have worked on.

Thanks,

 

[Gregg]

To be truthful this isn"t a do it yourself job. I have my A transport license and I would think of messing with the brakes.

 

[Mike Burton]

I have to agree with Gregg. If you're not experienced with air brakes, take it to someone who is.

 

[Anonymous-0]

The small line you have off comes from the foot valve to the service valve. When you press the foot pedal it sends air to the service valve which in return send air to the brakes (brake chamber).I would look and see if there is another valve that is close a (park brake valve) either one could be the problem

 

[Bob]

Are BOTH "pucks" good in your "spring brake" chambers?