Air Parking Brake

[mclee47]

We recently bought a 2014 Allegro RED on the Freightliner chassis. I am new to diesels with air brakes. After I am parked for several days, the air brake button is hard to release. Push it in, and it pops right back out. I have to hold it in for up to a minute to get it to release. After that it works just fine. Is that normal, or do I have a problem?

[mclee47]

I agree with you, moisheh. Next time I am near South Carolina, I am going to the Freightliner facility and take their class.

[moisheh]

Welcome to the world of air brakes. Your first post is an example of why every driver of an air brake vehicle should be required to take a basic course and pass a test. No driving skills. Just a basic understanding of how air brakes function. This is law in Canada.

Moisheh

[mclee47]

Executive, it's a 2014 and have corrected the signature. That was a typo.. Bill, I am a member of the Tiffin forum, but there does not seem to be much activity there. Others, thanks for all the air brake references. I have dome some reading on air brakes, including the parking brake. However, somehow I missed the point about minimum air pressure to release it. I do remember during walk around being told to let the air pressure build to 100 pounds before moving to ensure good braking, but they said nothing about the parking brake. The answer was obvious when I heard it. Luckily, I have not rolled in to a ditch or my barn in climbing the learning curve.

[Executive45]

mclee47 wrote:
We recently bought a 2014 Allegro RED on the Freightliner chassis.

Just curious...your signature says it's a 2013.:h..Dennis

[Bill_Satellite]

Be sure to join the Tiffin forum. If you want the best information on your RV (past, present or future) this is likely the best resource on the internet.
http://www.tiffinrvnetwork.com/forum/

[hooligan]

Lee- Congratulations on the new rig. Some lite reading on air brakes...

Air Brake manual

[mclee47]

Just figured that out. The air pressure has to come up before the brake will release. Thanks everyone.

[wolfe10]

All correct.

Front brakes are air APPLIED.

Rear brakes have two separate cans, one air APPLIED for service brakes (same as fronts) and the other spring applies air released. Most release with 45 or so PSI.

But, with air suspension, you are not going to want to move until air pressure reaches normal operating range which is generally 105-120 PSI.

[tkcas01]

Ivylog wrote:
You need to read up on air brake operation. Until the air pressure gets above 60 psi it's not going to stay in... brakes released.

Right. My understanding is that the emergency/parking brakes are applied using springs and it takes air pressure to release the parking brake. So yes, there must be sufficient air pressure to release them.

[Ivylog]

You need to read up on air brake operation. Until the air pressure gets above 60 psi it's not going to stay in... brakes released.

[MountainAir05]

What is your air pressure reading when you are trying this?