Just wondering if anyone has had their air parking brake stick on them after coach has sat for a bit. I was on travel for a few weeks and the coach sat for about three to four weeks. and when I started it up today to fill it up for our trip, the coach would not move. I reset the brake a few times with nothing. I then stepped on the gas and it made a clunk noise and moved a bit but still felt stuck. I then put it in reverse and it freed' the brakes up and no more issues. drove it and reset them a few times and all works well. Not sure if it was from sitting or if I have an issue.
Ours have done that a few times. If you are sitting in a area with lost of dampness it could happen. When called for support they were going to send someone out, but I asked what they were going to do and they said they were going to just rock the motorhome back and forth until they poped loose. Just did it myself and saved the wait.
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2011: 54 days, 2012: 218 days, 2013: 175 days, 2014: 196 days
2015: 188 days, 2016: 72 days, 2017: 185 days: 2018 182 days
2019: 156 days (2009 Berkshire, 390QS, and toad)
Had your air pressure built up the the full 135 lbs??
The parking brake engages by a LACK of air pressure.
The brake is released by a CHARGE of air pressure.
Basically, two HUGE springs hold the brakes on; when you release the park brake, the air pressure overrides the strength of those two springs. So at low pressure the springs are overriding the force of the air.
Air brakes are made that way (as a safety feature), so that if you suddenly lost all air pressure in the system, your park brake will automatically engage.
In fact, if you repeatedly pump your brake pedal in a rapid manner (with the park brake OFF; knob pressed down), you will slowly deplete the air tank pressure. When it hits around 40 PSI, your yellow brake knob will automatically 'pop' up.
Air pressure was full, I did my usual routine of start the coach, retract the jacks, turn jack power off and then wait for the air discharge and do my quick walk around. Hoping it was the moisture from sitting and the rain and being covered with the soft Vinyl covers from camping world. Seemed to be fine the rest of the time. Hopefully no more issues!! Thank
You for the information since these systems are so complex it's always good to know as much as possible about them.
If so, this in not a good indicator that you have full air pressure.
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2016 F350 6.7L LB CC Reese 28K 2014 Chaparral Lite 266sab
"Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety." 2014 19 days camping 2015 17 days camping201620 days camping
If so, this in not a good indicator that you have full air pressure.
Once the coaches air tanks are completely full they give a air discharge sound. This is normal and a sign that you're full. Also the gauges in the coach were showing full.
Once the coaches air tanks are completely full they give a air discharge sound. This is normal and a sign that you're full. Also the gauges in the coach were showing full.
Jason
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Umm, No.
The purpose of the air tanks is to HOLD air and to provide enough air for the brake cans to apply the brakes, not discharge it.
The sound you are hearing is most likely an air brake system air dryer popping off.
This is normal as long as the air dryer is working as it should and has had some maintenance done to it.
The air gauge on the dash should be the only thing used to determine when the air system is full.
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2016 F350 6.7L LB CC Reese 28K 2014 Chaparral Lite 266sab
"Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety." 2014 19 days camping 2015 17 days camping201620 days camping
The berkshire's have automatic heated moisture ejectors which for the air system which provides air for the brakes and suspension. Freightliner recommends draining
The tanks manually every six months which my coach is less than a year old and I did at the six month mark. The air is actually used to keep the brakes off or free. As you lose air the brakes will set as boowho previously stated in his post. I'm not certain what the air discharge noise is once the tanks are full, but when they get low, the air compressor turns on and the gauges go to full. Once they are full the coach makes the discharge noise again. This is a normal cycle that occurs once the tanks are filled up.
Jason, that air discharge is basically a pop off or relief valve. Once the tank and air system reach a certain pressure the valve opens allowing air pressure to bleed off. It happens often even as you are driving down the road.
I believe we all use this sound as an indication that our air pressure is built up to spec. But ole Ford is correct in that we all need to check our gauges to insure the pressure is correct.
Now that doesn't mean one of us can't have a faulty air gauge either, I like the three fold method, I crank up, watch as my Berk rises, listen for the air discharge as I am walking around the coach, then once inside I check the air gauge.
The brakes sticking to the drums after a 2 or 3 week time period is not uncommon on semi trucks and trailers witch have the same basic air brake system as your coach. As far as the air dryer exhausting yes you can count on that to tell you that the system is full of air as the air governor sends a burst of air to unload the compressor at 130 to 135 psi and that is the same burst of air that purges the dryer
The brakes sticking to the drums after a 2 or 3 week time period is not uncommon on semi trucks and trailers witch have the same basic air brake system as your coach. As far as the air dryer exhausting yes you can count on that to tell you that the system is full of air as the air governor sends a burst of air to unload the compressor at 130 to 135 psi and that is the same burst of air that purges the dryer
Yes, that "woosh" sound is the governor blowing off the excess pressure as you stated.
But an additional piece of info is that the compressor is clutchless and NEVER stops running (AFAIK, it is gear driven directly off the engine itself) and therefore is always operating (compressing), which is why you hear the governor blow off the excess pressure every so often.
As far as draining the tanks..... I pull my cables every few months whenever I happen to think of it. I have NEVER gotten more than a teaspoon or so of moisture out, even when I drove 18 wheelers.
Finally, the REALLY big problem would be during the winter, when that moisture could freeze and possibly render the entire brake system useless.
Bohoo maybe i did not explain it in enough detail. yes the compressor is direct driven by the engine but it also has what is called an unloader valve when it opens it does not allow the compressor to build air the air governor is usually mounted directly to the compressor on the air governor there is 2 lines one line monitors the air pressure in the tank when the air pressure reaches the governor max setting the pressure moves the valve in the governor allowing the passage to the unloader valve to open thus preventing the compressor from building any more air in the tank the whoosh of air you hear is the air dryer purge valve opening for a short time to blow any moisture out of the bottom of the dryer this is done at the same time your compressor unloader valve opens so you see even though the compressor is direct drive it does basicly shut off and when you hear the whoosh your system is full.
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