Now that I have the coach back AND a day off (those two haven't happened together in the last few months!), I am outside trying to get as much done to the coach as I can. Anyway, now that I found out I have to get a class B (Texas) license, I thought I would run over the low air pressure sequence which is required but the DOT. Long story short at 60 lbs., no light no buzzer but the emergency brake did pop out as it is supposed to. Question: DOT is looking for an audible alarm, OR warning light OR both. Am I wrong, I thought the coach did have some kind of warning system other than just the brake coming on?
I called and spoke to Keith at MOT and he said all the coaches are different and to let the pressure drop to a lower level (below 60lbs) at which point a light or buzzer may come on....but I'm thinking that would not do my ANY good if the brake has kicked in at 60 lbs and I'm in the left lane.....Anyone know about what is SUPPOSED to happen?
Thanks,
dave
You need to hear from a fellow 2002 model owner for the exact answer, but yes you are correct - you should get a low air pressure warning before your emergency brake pops out. How far before, what kind of warning, and at exactly what (indicated) pressure, might be variable. Have you looked in your Owner's Manual, to see what it says? There should be a diagram and/or description of the warning lights on your instrument panel - do they include a Air Pressure light? If so, and if you are not seeing it, then further trouble-shooting will be required.
The warning (whatever it is), will be triggered by a pressure switch (or two switches) located somewhere in your air brake system. Your air system diagram should note the switch location. If the switch is bad, or one of the connecting wires is loose or broken, then you will not get a warning.
This definitely needs to be corrected before you go for your driving test.
According to the Federal regs, a light and a secondary warning device(ie: buzzer or other such as a wigwag) are supposed to "alarm" prior to the air supply button/control lever sets the brakes @approximately 60 lbs..
After my post I went back and tried again. With the engine running, I let pressure get to 120 lbs., begin pumping brakes, at right around 90 lbs. the "level system" light comes on along with a chime. At 40lbs the emergency brake activates. I will as you suggest look in the manual for what is specific to my model year. Thx.
dave
Sounds like you need to replace the protection valve(s) as the regs say 60 lbs not 40.
I get a light and chime (which drive my Jack Russell nuts) at 70 psi and 60 psi emergency brake activates.
John
You are seeing the "Level System" low pressure light. It should come on around 80-90 psi. The switch that activates that light is mounted on the rear six-pack manifold. (See HWH page linked below)
"Pressure switches used to monitor system air pressure are usually set at 85 psi, although some manifolds have a pressure switch set at 100 psi."
The "Air Pressure" warning is a different deal - it should come on (like John says) just slightly above 60 psi. These are two
different warning signals, monitoring two
different systems, activated by two
different pressure switches.
For the brakes the low air pressure alarm should sound at about 60 psi and the park brake should activate around 45 psi .
On my couch (2003 U320) the alarm is the annunciator and is plumbed through the mysterious blue box. No warning light.
Steve
As SteveB suggests (above), I think your emergency brake is coming on "early". It is more common for this to happen at about 30-40 psi. In the event of a massive air leak downstream of your "front" and "rear" air tanks, your protection valves should hold pressure in your brake tanks at about 60 psi. At that point, you still have sufficient pressure to operate your service brakes, and the emergency brake should
not activate.
If the pressure in one or both tanks continues to drop, then around 30-40 psi the emergency brake knob should pop out. The exact pressure at which this occurs depends on the "spring" installed in the Bendix PP valve. These springs are available in 20, 30, 40 and 60 psi ratings, so it is
possible that your emergency brake control has a 60 psi spring. See manual linked below:
BENDIX PP-1-2-5-8-RD-3 PUSH-PULL VALVES MANUAL Pdf Download. (http://www.manualslib.com/manual/392660/Bendix-Pp-1-2-5-8-Rd-3-Push-Pull-Valves.html#manual)
Seemed high to me also, so I just went out and checked....1) Get alarm at 65psi, Push/pull pops out at 40psi, Brakes will not release nor will chime and light quit until 70psi. Thats the way mine is set-up.....Sorry for inaccurate info earlier.
John
In that case, your annunciator would
already be sounding due to the LEVEL SYSTEM alarm being activated at approx. 85 psi, and having the AIR PRESS alarm set at 60 psi would be superfluous. Unless, of course, there are two separate distinctive alarm sounds?
Or, perhaps on the newer coaches, the LEVEL SYSTEM light does not trigger the annunciator? On our '93, if
any warning light along the top of the panel comes on, the annunciator screams. Plus, of course, other times also, like turn signals, etc.
Seems like everything is coming on at the wrong pressure?
Think I would check to see if the pressure gage is correct before I started chasing other things.
Yes it is confusing. Are there any 2002 owners out there
Yes confusing for sure. Are there any 2002 owners out there who are familiar with how our year coach behaves in this situation?