Community Forums

rivrduk · 08-06-2011, 10:26 AM

Not sure what these are called, but they air up each time i start the motor. The front ones go to 130 psi and the back ones only go to about 110. However, after a short time driving the back ones come up to 130. Even with back ones at 110 the buzzer at the dash stops buzzing. Is this normal. Rivrduk

CHCam42 · 08-06-2011, 10:43 AM

I would suggest that you read the section in the owners manual that covers air brake and how they work.

Kjlunda · 08-06-2011, 10:49 AM

Quote:

Originally Posted by rivrduk

Not sure what these are called, but they air up each time i start the motor. The front ones go to 130 psi and the back ones only go to about 110. However, after a short time driving the back ones come up to 130. Even with back ones at 110 the buzzer at the dash stops buzzing. Is this normal. Rivrduk

What type/year coach do you have. If it's a diesel pusher, those gauges on the dash are for your air brake system.

JimM68 · 08-06-2011, 11:35 AM

Reading the manual is a good idea...

Mine has 2 air tanks, one for the front and one for the rear.
2 air pressure gauges, one for the front tank one for the rear.
Normal pressure on mine id 115 psi.
Below 65 psi, I get a low air pressure warning, both a light and a gong.
Also below 65 psi, the air bag suspension does not inflate, it's saving what air it has for the brakes.
While I'm certain my brakes will work at 65 psi, I do not ever try to move my coach until she has pumped up to 115 and I hear the regulator "blow off"

Again, this is a complex system, and it's important to understand how it works, how to maintain it, and what to watch for so you know if there is a malfunction. It will all be detailed in your manual, give it a good read.

RickO · 08-06-2011, 12:01 PM

By all means educate yourself on the operation and maintenance of air brakes. Some states even require a special license for operators of rigs with air brakes so it's important to understand what's going on there. BTW, if your air pressure were to drop too low (~60lbs?) your back brakes will probably lock up and bring you to a rapid halt.

Good luck...

Rick

MaverickBBD · 08-06-2011, 01:07 PM

Quote:

Originally Posted by JimM68

Reading the manual is a good idea...

Mine has 2 air tanks, one for the front and one for the rear.
2 air pressure gauges, one for the front tank one for the rear.
Normal pressure on mine id 115 psi.
Below 65 psi, I get a low air pressure warning, both a light and a gong.
Also below 65 psi, the air bag suspension does not inflate, it's saving what air it has for the brakes.
While I'm certain my brakes will work at 65 psi, I do not ever try to move my coach until she has pumped up to 115 and I hear the regulator "blow off"

Again, this is a complex system, and it's important to understand how it works, how to maintain it, and what to watch for so you know if there is a malfunction. It will all be detailed in your manual, give it a good read.

A little clarification may be in order. It may look like you have two tanks put in actuality you have five tanks. A wet tank, easily identifiable by the automatic dump valve on the bottom. This is where the air from the compressor enters. A primary tank, which controls the air to the rear brakes. A secondary tank, that control air to the front brakes and customer supplied manifold as well as your leveling (air bags) . Thus the front and rear nomenclature on the dash gauges. Then two ping tanks, that receive air from and give back to the air bags. Technically your rear brakes should be enough to stop your coach. That is why the alarm stops at 65 psig. I say technically because your air bags are probably still inflating and in my case it would not allow the front wheels to clear if I decided I wanted to make a turn. At somewhere around 110#psig your secondary tank should be up to pressure and you have front brakes and you should be at ride height. That is when you hear the psssst of the automatic dump valve opening to blow out any gunk (water) in you wet tank.

Hope this helps.

ga traveler · 08-06-2011, 04:35 PM

The purpose of the guages is to tell you when it is safe to drive. Your brakes are not put on with air, they are taken off with air. It takes 65 psi to release the brakes.
full air brakes are applied by very strong springs. When you apply the brakes you are actually taking air away and letting the springs apply the brakes. When you pull the yellow park break you can hear the air release. That stops all air and lets the spring set the brake.if you lose air pressure underway, your brakes will come on.

ga traveler · 08-06-2011, 04:44 PM

Just a side note. When i used to deliver a motorhome to a customer (delivery checkout) I would always caution them. If they had young children in the coach and left them alone, always shut off the engine and then pump the brake pedal until the pressure was below 50 psi on both guages. This would set the brakes and the yellow park brake would not release. this was after we had two different customers children release the park brake and wipe out the neighbors house.

RickO · 08-06-2011, 07:29 PM

Great write ups Maverick and ga traveler! Thanks much for sharing.

Rick

JimM68 · 08-07-2011, 07:04 AM

Quote:

Originally Posted by ga traveler

shut off the engine and then pump the brake pedal until the pressure was below 50 psi on both guages. This would set the brakes and the yellow park brake would not release. this was after we had two different customers children release the park brake and wipe out the neighbors house.

I always dump all the air whenever I park the coach.
That way it levels much closer to the ground too.

Skip426 · 08-07-2011, 01:13 PM

Quote:

Originally Posted by ga traveler

The purpose of the guages is to tell you when it is safe to drive. Your brakes are not put on with air, they are taken off with air. It takes 65 psi to release the brakes.
full air brakes are applied by very strong springs. When you apply the brakes you are actually taking air away and letting the springs apply the brakes. When you pull the yellow park break you can hear the air release. That stops all air and lets the spring set the brake.if you lose air pressure underway, your brakes will come on.

ga,a little point here; Only the park brake is a spring applied, air released, brake. During regular braking air is applying the brakes at the chambers, front and the lower of the two chambers in the rear, these chambers are spring return. Lack of air pressure will about 60 psi, cause the rear park brake chamber, top of the two stacked at at the rear brakes, to over-ride the lower chamber and start to drag the rear brakes and below approx. 45 psi go to full apply. Locking the rear wheels only to allow steering.

ga traveler · 08-07-2011, 01:30 PM

Quote:

Originally Posted by ga traveler

The purpose of the guages is to tell you when it is safe to drive. Your brakes are not put on with air, they are taken off with air. It takes 65 psi to release the brakes.
full air brakes are applied by very strong springs. When you apply the brakes you are actually taking air away and letting the springs apply the brakes. When you pull the yellow park break you can hear the air release. That stops all air and lets the spring set the brake.if you lose air pressure underway, your brakes will come on.

Quote:

Originally Posted by Skip426

ga,a little point here; Only the park brake is a spring applied, air released, brake. During regular braking air is applying the brakes at the chambers, front and the lower of the two chambers in the rear, these chambers are spring return. Lack of air pressure will about 60 psi, cause the rear park brake chamber, top of the two stacked at at the rear brakes, to over-ride the lower chamber and start to drag the rear brakes and below approx. 45 psi go to full apply. Locking the rear wheels only to allow steering.

I don't have first hand knowledge on air brakes. The system I was talking about was a coach we had on our lot that we had to have a specialist come out and fix the brakes. This was the way he described the system on this coach to me. The only thing i know for a fact is, if the pressure gets low the brakes will come on. (had it happen on several Tourmasters.)

Skip426 · 08-07-2011, 05:27 PM

Quote:

Originally Posted by ga traveler

I don't have first hand knowledge on air brakes. The system I was talking about was a coach we had on our lot that we had to have a specialist come out and fix the brakes. This was the way he described the system on this coach to me. The only thing i know for a fact is, if the pressure gets low the brakes will come on. (had it happen on several Tourmasters.)

All modern coaches will have the rear;park ; brakes come on in a low air situation. Only way to move the coach is to build air in the system , with the engine mounted compressor , or introduced air through the manifold.

The other method; cageing the springs is an absolute, last resort best left to the tow truck driver.

JimM68 · 08-07-2011, 08:49 PM

Quote:

Originally Posted by ga traveler

The purpose of the guages is to tell you when it is safe to drive. Your brakes are not put on with air, they are taken off with air. It takes 65 psi to release the brakes.
full air brakes are applied by very strong springs. When you apply the brakes you are actually taking air away and letting the springs apply the brakes. When you pull the yellow park break you can hear the air release. That stops all air and lets the spring set the brake.if you lose air pressure underway, your brakes will come on.

Quote:

Originally Posted by ga traveler

I don't have first hand knowledge on air brakes. The system I was talking about was a coach we had on our lot that we had to have a specialist come out and fix the brakes. This was the way he described the system on this coach to me. The only thing i know for a fact is, if the pressure gets low the brakes will come on. (had it happen on several Tourmasters.)