How can you tell if air brakes are in need of service?

[Ted Lambert]

Originally Posted by 96 Wideglide

I think the NTSB link is refering to crawling under with 3/4" wrench in hand !

Are you sure the size of wrench you have is correct? Those slack adjusters must be monsters!

[Ted Lambert]

Originally Posted by twinboat

For people who are new to air brakes. Although that is the basic procedure, there is a bit more then that.

You need to make sure the air pressure is up, the wheels chocked and the parking brake is off, if you are checking the rear brakes. If you turn the adjusters the wrong way, you loosen your brakes. ( I've seen it )

I understand that the DOT inspectors, are real sticklers about brake adjustments.

Since MHs don't stop at inspection stations, I would let the self adjusters do their job.

You should do a visual inspection of slack adjuster movement, as recommended, and if there is a excessive of movement, get an air brake shop to inspect the brakes.

But even the visual inspection, is with the parking brake off, so blocking the wheels and an assistant is necessary.

There seems to be a consensus about pumping the brakes before a trip, to adjust them. Running the air down to check recovery time, is part of the air system check, anyway. It won't hurt anything.

Now, about the mechanics of self adjusters. As the brakes wear, the slack adjuster moves a longer distance, out. If it moves to far, it ratchets a bit to shorten the movement. If you are light on the brakes, there is less wear, so there should be less movement.

If you are not wearing down your brakes, how are they coming out of adjustment.

Another point, although only applying to the rear, spring brake, is, when you set the parking brake, the spring pressure will force the slack adjusters out, almost as far as a heavy brake application. When you release the parking brake, if there was to much movement, the auto adjuster will adjust it.

Just my take on things.

Very well said!

[Ray,IN]

Originally Posted by Gary RVRoamer

You want a truck chassis shop, not an RV dealer, to check or repair air brakes. A few large RV stores have qualified chassis departments, but most are not experts or even knowledgeable amateurs on chassis problems.

Auto slack adjusters work best with hard braking, and motorhomes generally don't get much of that, so the general suggestion is to brake sharply now and then, both in forward and reverse, just to give them a chance to do their thing.

Air brakes have a slight lag between pedal and braking - could that be the "wooden" feeling? Was the air pressure up in the tanks, i.e. dash air gauges showing about 125 psi? The brakes work all the way down to around 65 psi, but reduced air pressure would change the feel. Normal operation of the air system is right around 125 psi. Anything less for more than a few moments indicates a significant air leak or a compressor problem.

Other than that, you tell if the brakes are working by how well the coach stops, straight and steady. It is rare for a motorhome to need new brake pads or anything like that - the brake system is made for much greater wear & abuse than most any motorhome ever sees.

You are right. Here is the explanation from Idealease with more details.

[DMTTRANSPORT]

Originally Posted by Ray,IN

You are right. Here is the explanation from Idealease with more details.

Truck or Coach, I keep them Manually adjusted it's a simple task! and a peace of mind.......

[Ted Lambert]

Originally Posted by DMTTRANSPORT

Truck or Coach, I keep them Manually adjusted it's a simple task! and a peace of mind.......

Well said. Anybody can do it just gets somebody who knows what they are doing to show you.
Also the best way to tell if they need replacement is doing a cam rotation. Cam rotations should be done on a yearly basis. Although you don't have a commercial vehicle you have the same complex system that commercial vehicles have. Take some time and find out what is required for brakes on commercial vehicles it is simple once you know what to do. I held an inspection licence for years. But really it is not rocket science. Highway transport departments should be able to supply you with a book at minimal cost to show what is required. As far as I'm concerned every DP owner should have the knowledge to inspect and determine when repairs are required.
Although I guess a person can wait till they fail than get them repaired while the DW is recovering in hospital!

[96 Wideglide]

Originally Posted by narampa

Are you sure the size of wrench you have is correct? Those slack adjusters must be monsters!

I 'did' take a air brake course, just a couple of years ago ! 9/16" sound about right ?

[flaggship1]

Originally Posted by narampa

Although I guess a person can wait till they fail than get them repaired while the DW is recovering in hospital!

You're kidding right???
I suppose it could happen. But I don't recall "the air brakes failed and DW" was in the hospital posts. Hope it never happens to anyone - but annual inspections, daily driving and always looking at the pad before departure seems sufficient. OK flame on, but knowing the coach - watching the computer, the ground, etc combined with routine maintenence works for me.

[CampDaven]

Originally Posted by flaggship1

You're kidding right???
I suppose it could happen. But I don't recall "the air brakes failed and DW" was in the hospital posts. Hope it never happens to anyone - but annual inspections, daily driving and always looking at the pad before departure seems sufficient. OK flame on, but knowing the coach - watching the computer, the ground, etc combined with routine maintenence works for me.

10-4 bro!
A good tech works every time, along with the ol "look see" by us.
I do believe in hard braking at low speed (10 mph) forward/backward a couple times a year keeps them tuned up.

[TheArnolds]

Individually this may be good information applicable to your year/make of chassis recognizing that many who posted are talking about chassis that are 10-15 years old. I just read the instructions about air brake adjustment for my 2014 Freightliner chassis and it is nowhere as complex as some of what I have read on this thread.

After saying all this, what I suggest is you check the maintenance and operation instructions for your specific chassis and follow those instructions. You may be saving yourself a lot of work or maybe trouble by performing some of the recommended procedures not understanding that one size does not fit all.

[96 Wideglide]

Your air brake system in your '14 Freightliner is no different than any other system. They 'dumb down' the instructions in RV manuals, because they know the owner likely has no training in air brake systems.

[TheArnolds]

Originally Posted by 96 Wideglide

Your air brake system in your '14 Freightliner is no different than any other system. They 'dumb down' the instructions in RV manuals, because they know the owner likely has no training in air brake systems.

Have you read the Freightliner manual for my chassis? BTW, this is not my first Freightliner chassis, just my newest. People here are recommending adjustment procedures that are specifically not recommended by Freightliner. All that stopping 8 or 10 times are for adjusting NEW breaks and if you need to manually adjust it may be hiding a problem and to take it to an authorized repair station. All I suggested was to read your chassis manual, is that a bad recommendation? You are also telling me that air break technology is stuck in time and what was recommended 15 years ago holds true today.

[flaggship1]

Originally Posted by TheArnolds

Have you read the Freightliner manual for my chassis? BTW, this is not my first Freightliner chassis, just my newest. People here are recommending adjustment procedures that are specifically not recommended by Freightliner. All that stopping 8 or 10 times are for adjusting NEW breaks and if you need to manually adjust it may be hiding a problem and to take it to an authorized repair station. All I suggested was to read your chassis manual, is that a bad recommendation? You are also telling me that air break technology is stuck in time and what was recommended 15 years ago holds true today.

Well played sir. Well played.
The air portion of air brakes is by far the bigger concern to me. I am more concerned about keeping the air operating correctly than I am the brakes - and I'll let the brake man and real mechanics deal with it. My role is to watch and know the performance and recognize changes. Others want to touch everything - some know what they're doing - some don't. Some ask what to do. I leave it to the shop. It's just my preference.

[Ted Lambert]

Originally Posted by flaggship1

You're kidding right???
I suppose it could happen. But I don't recall "the air brakes failed and DW" was in the hospital posts. Hope it never happens to anyone - but annual inspections, daily driving and always looking at the pad before departure seems sufficient. OK flame on, but knowing the coach - watching the computer, the ground, etc combined with routine maintenence works for me.

Not kidding at all!
Why should a couch be immune to inspections or at least the drivers have an air brake endorsement on their operators licence.
Experience is great but don't forget everything above the frame is pure truck.
Respect it and learn what makes it tick.
You mention annual inspections. By who?
Yes it probably works for you and I'm not talking about you.
I'm talking about t h e people that think there driving car taking the kids to school.
Next time your in park talk to the people with the big coach's. I have there are a lot that don't know the first thing about air brakes . I get that from asking questions and it amazes me the answers I get. 90 percent know what they are doing a lot of fellows with truck experience or mechanical aptitude.
I'm just playing the devils advocate.
It's the 10 percenters that I worry about.
Sorry if I offended you. The people out there will know who I'm addressing.
And I really recommend cam rotations yearly as they are the only way to determine the condition of the brake components. It done on trucks in order to pass the CVIP inspection so why not coaches.
For those who don't know what a cam rotation is. It is a test that can accurately check wear in the. S CAMS. Slack Adjusters.Overall travel which includes shoe to drum clearance. A lot of people don't realize that just because the show and drum have no wear. The other components may be junk.
Used units might have just had shoes and drums replaced but what about the components that make them work.
S cams and S cam bushings along with wear in slack adjusters can make for a disaster if they are not checked. Only a cam rotation will determine the overall wear in the system.
When buy a used coach insist on a cam rotation as part of the deal. Shoes and drums are cheap and are a great shortcut to dump a used unit. The other components can cost more as they can be labour intense of not serviced regular.

My comment about the wife n the hospital was pure satire. I believe a lot of people wont be sharing their misfortunes about accidents and what we do see is probably a very small percentage.
Safe travels everybody!

[flaggship1]

^^ no longer offended by anything on this forum or anywhere these days. Life on the road is too much fun. I pay professionals - Freightliner - Cummins - Independents - to do their job. I like it that way... I wasn't a mechanic by trade and will not be in retirement. And if I were going to be, I wouldn't take my training here.