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air brake "low air warning" signaling device

Yahoo Message Number: 76346
Hello all and happy holidays,

We have a 2006 Allure 430 and while testing for our Nevada Class B license we were asked about the air brake "low air pressure" warning device which should activate prior to the parking brake suddenly engaging due to low air pressure. What we are curious about is whether we have such a device on our coach and if so, is it a sound or a light and that perhaps ours is malfunctioning.
I would appreciate any feedback that can be offered as it seems to me that the low air warning device would be very significant to keep the parking brake from engaging at any speed due to low air pressure to the brake lines.
Thanks in advance,

Jerry Keller

2006 Allure #31347

Re: air brake "low air warning" signaling device

Reply #1 –
Yahoo Message Number: 76347
Maybe this will help.

The air compressor supplies 2 or 3 tanks depending on the coach. They are a front air tank, a rear air tank and an aux tank for step slides, air horn, suspension etc, if equipped. The air compressor supplies these tanks via a common manifold, each tank has a check valve to prevent air from flowing back into the manifold. The air compressor is set for 120 lbs max +-, at 90 or slightly above it should cut in and cut out at 120. The low air buzzer and or light should come on between 70 and 90, if the pressure drops below 60 the spring brake will apply the spring brakes, usually only on the drive axle.
It is a warning system only it will not prevent the spring brake from applying.

Mikee

Re: air brake "low air warning" signaling device

Reply #2 –
Yahoo Message Number: 76350
First , it is easy to check the Low Air Pressure Warning. With the ignition on, pump your brake peddle. You should see the air pressure dropping , on the dash gauge. You then can note the pressure when the warning is heard, but there should be a light as well. Second, you seem unaware of how the air brake system works. If there is no air in the tanks, the Emergency or Spring Brake is applying pressure , on the brake pads to give you Brakes. As the air pressure builds the air pressure pushes the spring , and at about 65 PSI the spring is over ridden. ( there is a diaphragm between the 2 sides ) You need to get to 130PSI to have the same effect as the spring brake. The air system typically cycles, as Mikee says , between 90 and 130 PSI. The only way the Emergency brake would come on, in an instant fashion, is if there was a massive air leak, and the system pressure dropped to Zero PSI ( if it got to 30 PSI in the tanks, the spring/emergency brake would be 1/2 applied ) and the spring brakes would be fully applied. I suggest , strongly , you understand how the brake system works. You cannot pump the brakes like in a car, which has hydraulic brakes, as you can pump the air out, as described above. Even with the engine running , the air compressor cannot keep up, with repeated pumps of the brakes. I am not judging you , other than saying , if you understood how the air brakes worked, you would not have asked the question. It is REALLY important to understand how it works. This is a huge safety issue

Ron Baran 09 Magna 7025

Re: air brake "low air warning" signaling device

Reply #3 –
Yahoo Message Number: 76354
My Question: Is loosing air, when parking the MH for a couple of days normal? After sitting on a campsite for a week or so I noticed both air pressure gauges show below 40 psi with Low Air Pressure Warning sound when starting the diesel. Two minutes later, pressure climbs over 100, then I press the Travel Mode Switch, wait for the "puff" @ 120 psi and ready to fly out.
My question again: Is loosing air normal when parking for a couple of days or do I have a problem?

Bert 08 Magna 6909-CAT C15

Country-Coach-Owners@yahoogroups.com, "RonaldB" wrote:

Re: air brake "low air warning" signaling device

Reply #4 –
Yahoo Message Number: 76355
Jerry:

This document is in the 'Files'. Air Brake check&test.pdf
I keep a copy in my coach. Thanks for reminding me that I have it.:-)
When I first followed these instructions, I realized that the light on the dash was not bright enough and there was no buzzer. Had one installed a week later. To me a buzzer should have been included as a matter of safety and common sense by CC. But the is behind us now. I hope that no one ever has to experience this type of emergency. Safe travels.

Gil B

'05 Inspire
51322

Re: air brake "low air warning" signaling device

Reply #5 –
Yahoo Message Number: 76357
We park our 07 Allure for a month at a time and only lose a few pounds.

Jim

70 Allure #31570

Re: air brake "low air warning" signaling device

Reply #6 –
Yahoo Message Number: 76359
Jerry,

I don't believe that CC equipped our coaches with audible alarms such as the license inspector asked about. At least my 2004 Allure doesn't have one.
There is a low air warning light on the dash. You should see it illuminate briefly when you switch your ignition on. I think.

George in Birmingham
'04 Allure 31038
George in Birmingham
2003 Magna 6298

Re: air brake "low air warning" signaling device

Reply #7 –
Yahoo Message Number: 76361
I believe all air brake systems have a low air pressure alarm. I know my 1995 does.
If you perform the DOT pre trip air brake tests on your rig, the brake fanning step will result in your park brake knob popping out at about 40psi and the alarm to sound at about 60psi. If either one does not happen you need some repair work done ASAP.
(You will also be resetting your slack adjusters during the pre trip air brake test.)

Dean

1995 Magna 5280

Re: air brake "low air warning" signaling device

Reply #8 –
Yahoo Message Number: 76362
I do not have a warning alarm on my 2005 Inspire. I do have a warning light. I loose most of my air if I sit for more than two weeks.

Jock Vargo
2005 Inspire
51428

Re: air brake "low air warning" signaling device

Reply #9 –
Yahoo Message Number: 76363
Dean,

Many CC motorhomes do not have an audible alarm. For example, the 2004 Allure. Visual warning is there.

George in Birmingham
'04 Allure 31038
George in Birmingham
2003 Magna 6298

Re: air brake "low air warning" signaling device

Reply #10 –
Yahoo Message Number: 76364
I think the audible alarms are required on commercial vehicles, ones a CDL is required to operate. The very first ones I saw were a spring loaded device above the windshield that dropped a red flag with "LOW AIR". Late 60's. Before spring emergency brakes.

Leonard

97' Magna 5418

Re: air brake "low air warning" signaling device

Reply #11 –
Yahoo Message Number: 76365
Dean do you have automatic slack adjusters?? How do you adjust them for DOT? I have a light but do not remember if I have a audible alarm.

Vick Welsh

99 Intrigue 10714

Re: air brake "low air warning" signaling device

Reply #12 –
Yahoo Message Number: 76366
Ron,

Thanks for your response. I do have a good understanding of the air brake system, how it works, and how to check for air by pumping the brake pedal while the ignition is in the "on" position. When I do that however, there is no warning sound or light as the air pressure drops until the parking brake pops out and engages the spring brakes. My question is whether or not my coach, a 2006 Allure, has an air pressure warning alarm, either light or sound, to alert me that the air pressure in the braking system is dropping prior to the parking brake, ie the spring brakes, being engaged and jolting the coach to a stop. So you see, I do understand the air braking system, Im just wondering if there is an indicator when the air pressure drops below safe levels.
Thanks,
Jerry

Re: air brake "low air warning" signaling device

Reply #14 –
Yahoo Message Number: 76368
Sorry, I did not complete my response earlier.
I understand the automatic slack adjusters will be adjusted as you apply the service brake to reduce the air pressure to 60psi. This should be done only with the spring brake (park brake) not engaged per the procedure instructions.

Dean

95 Magna 5280

Re: air brake "low air warning" signaling device

Reply #15 –
Yahoo Message Number: 76369
Hi Dean,

Thanks for responding. We are familiar with the DOT brake check procedure, had to demonstrate it to qualify for the required Class B license in Nevada, and were just wondering why there was no visible or audible alert ffor low air pressure when we went through the procedure of pumping down the air to the point of the parking brake popping out.
I think maybe our coach doesnt' have the alert or maybe it is malfuctioning.
Thanks again, best through the holidays, Jerry

Re: air brake "low air warning" signaling device

Reply #16 –
Yahoo Message Number: 76370
Hi George,

Thanks for responding and I think you have it right. No audible alert, only a light on the dash. I didn't see the dash light alert but I might have missed it. I'll check it again tomorrow.
The good news is that both my wife and I passed our Class B license tests even without the alert, Thanks, and best through the holidays, Jerry

Re: air brake "low air warning" signaling device

Reply #17 –
Yahoo Message Number: 76372
Jerry

My 2006 Alllure has a light only but it is very difficult to see.

Dan 2006 Allure 31348

Re: air brake "low air warning" signaling device

Reply #18 –
Yahoo Message Number: 76374
My 2000 Allure is same way. Visual light only. If you want an audible alarm it would not be difficult to add. A couple of diodes and small piezo buzzers (like those Radio Shack ones used on turn signals) could be added to warning light circuit. Buzzer would be set at same level as warning light.
There is an air brake test procedure in the files section I put up there several years ago. It is based on common CDL practices for commercial drivers.

Merry Christmas & Happy New Year!

Jim Hughes

2000 Allure #30511

Re: air brake "low air warning" signaling device

Reply #19 –
Yahoo Message Number: 76377
Hi Dan

Thanks for the reply, and most likely, since we are only one number before you, that we must have only the light and no audible alarm.
When I get out to the coach I'll check again for the dash light.
Best through the holidays,
Jerry

2006 Allure 31347

Re: air brake "low air warning" signaling device

Reply #20 –
Yahoo Message Number: 76382
I believe low brake air is among those things my Magna yells at me.

Rich 2002 Magna

Re: air brake "low air warning" signaling device

Reply #21 –
Yahoo Message Number: 76383
My Old Affinity yells at me for low rear and/or front low air pressure, among many other things. Non- critical things has a female voice, critical has harsher male voice...Fortunately I only have had to hear them at startup....never under duress.

Max

98 Affinity #5487 C12

Air Brake

Reply #22 –
Yahoo Message Number: 76348
I was once told (but have not experimented nor intend to) that if there is a sudden air lost, to put your hand on the air brake knob to keep it from popping up. It was said that this might give you a few seconds to get off the road before the rear brakes lock up. As I mentioned, you are on your own to experiment.

.Bill Dane 99 Allure 30326
 

Re: Air Brake

Reply #23 –
Yahoo Message Number: 76349
Be much better advised to keep both hands on steering wheel and pullover. The valve is reacting to the pressure in be brake system when it pops. At that point it has no control of the brake system. The spring brakes will come on when the pressure in the brake cans gets to low to keep the springs compressed. Nothing you can do in cab to change the outcome but be very thankful for spring brakes. At least you stop and do not go for a wild unwanted ride.

A leak down test is CDL requirement for a pre-trip. One can know how well your system is holding air by how much it leads off while setting.

Leonard

97' Magna 5418