What do I need to know about air brakes?

FIRE UP wrote:

Groover wrote:
I have driven my DP about 20,000 miles so far and everything is good but I was wondering why commercial licenses require an airbrake certificate and what you are expected to know to get that certificate. Is that something that I need to know? The manual mentions checking the air dryers annually and greasing the brakes. Someone advised me to watch the air pressure gauge to be sure that I am not loosing too much to leaks. Is there more?

I keep my rig under a roof rust should not be much of an issue.

Thanks!

Groover,
Well Sir, air brakes, the components that are used to make up the entire system, are phenomenally different than their brothers, Hydraulic brakes. Brakes are brakes, THEY SLOW OR STOP YOU, but how they're applied, what makes them work, things that you SHOULD know for use, application, maintenance, problems, etc. are quite a bit different than hydraulic ones.

In all reality, if you don't know that much or, almost nothing about your air brake system, my first bit of advice would be to get on the net, look up anything that would pertain to the system itself and, how they work and all that. Telling you to "check your slack adjusters" to a person like yourself, is like telling a person who knows nothing about computers, TO WRITE A PROGRAM FOR ONE.

There's quite a bit to air brake systems. It all starts with an air compressor, attached to the engine, that's gear driven internally. That compressor, basically is just like any home air compressor. Next in line is what's called a governor. It does, what the name implies. It controls the compressor to turn on, and, shut off. Those terms incidentally are termed, "Cut in and Cut out" pressures.

Since COMRESSING AIR causes heat, it will also cause moisture or water to develop in the system, NOT GOOD! So, next in line is what's called the AIR DRYER. Again, it does what the name implies. It, through one or two filters (some have one and some, two) dries the air, prior to it being sent out and delivered to the next phase, THE STORAGE TANKS.

The storage tanks are where all your built up air is held, until needed.

OK, that's the basics of the system. Now, as for your brakes. You have what's called a "treadle valve" for a brake application valve, under the brake pedal. When you step on it, you are allowing air, from the air tanks, to travel through that valve, through some lines, through other fittings and lines, through ABS systems (about 90% of the coaches now days have anti-lock braking systems integrated into them) and, into a final destination, what's called BRAKE CANS.

Now, those brake cans receive the air, and through mechanisms inside them, convert that to mechanical movement, to apply the brakes. Most of the air brakes in todays coaches are actuated by what's called an "S" cam. Basically, there is an axle, mounted right in the middle of the "S". As that axle turns, those portions of the S, rotate. When it rotates, there's little rollers that follow the S curves, and, those are attached to the brake shoe ends. Obviously, when the rollers follow the curves of the S, they travel outward which, in turn, pushes on the brake shoe ends which, in tern expand, and applies the shoes against the drums, neat huh?

That's the basics of how the brake systems work. There's a whole lot more to the system(s) but, that's the basics. Now, one more thing, INSIDE the REAR brake cans ONLY, are mounted some seriously strong, gigantic springs. Those springs are also what's used to apply the rear brakes. But, they don't apply them when your driving the coach. They are held back via a super large diaphragm and, a ton of air pressure.

But, when you park your coach, and pull that little YELLOW button on the dash or, where ever it's mounted, what you are doing is, releasing all that air, that's holding the diaphragm, which is holding the brakes in the OFF POSITON, to a allow those seriously large springs to apply those brakes.

By law and DOT rules and regs, parking brakes can only be applied and held on, by MECHANICAL MEANS! They cannot be applied and held on by air or in the other brake systems, hydraulics.

So, that's the basics of how your air and brake systems work.

As for maintenance, well, I could write another book here but, suffice to say, there's really not much. They're pretty self sustaining. You've been told to check to see IF you have slack adjusters. "Slack Adjusters", AGAIN, are just what the name implies. They basically take any SLACK out of the application system.

In hydraulic brakes, there are adjusting "Stars" inside the brake drums that can be rotated or, adjusted, to expand the shoes so that they are almost, if not actually touching the drums. That's done so that there's very little brake pedal needed to apply the brakes.

Well, the slack adjusters, used in air brake application, are the same thing. They basically "self adjust" to take up slack, when the brake shoes begin to wear which, causes a larger gap, between them and the drums. If that happens, your shoes travel farther out to come in contact with the drum and, in order for that to happen, you need more air and consequently, more pedal and, your brakes are not as efficient and effective either.

So, those slack adjusters are fairly important. Now, back to maintenance. One of the important things to check on a somewhat frequent basis is, check for moisture in the tanks. Sometimes, moisture gets past the air dryer and, accumulates in the bottom of the air tanks, not very often, but, it can happen, from time to time.

About 99.9% of your air braked coaches come with lanyards, attached to bleeder valves, mounted to the bottom of the air tanks. Not all, but most. Once you know where those are located, you can pull on them to see if any moisture is spit out the bottom of the tanks. I've pulled my a few times and, nothing has ever come out but, dry air.

On the S-cam shaft housing, from the brake cans to the brakes, is a lube fitting, that's used to lube that shaft and rotational points. You lube those every time you lube your coach. There are also lube fittings on the slack adjusters. Again, those are lubed at the same time. But, be frugal with the grease on both of those fittings.

As for the air dryer. Those are quite often, a neglected but, important part of the air system. Some guys on here, are capable of doing the required maintenance on them and, the replacing of the filters. In many of them, like mine, the air system has to be disconnected from them and, then they are un-bolted from their mounting position and, serviced on the bench. It's not all that hard to do that. On ones like mine, you DEFINITELY have to remove it to service it.

Now, how often does that need to be done?? Well, normally about every couple of years, plus or minus. I'm not sure what the actual, written maintenance schedule is, I just know my own maintenance schedule and, when things are in need of service. Those filters inside the air dryer, do get quite contaminated with dirt, debris, corrosion, and more so, it pays to get it serviced so your air system can work at it's prime efficiency and, you have waaaaaaaaaaay less chance of goofing up all the little valves and mechanisms in the air/air brake system.

Well, I'm sure you're quite tired of reading at this point. Hope I've helped here. There's a whole lot more to what I told you. I've given you, in comparison, one small paragraph of a book about the air system and air brake system.
Scott

cmeade wrote:

FIRE UP wrote:

Groover wrote:
I have driven my DP about 20,000 miles so far and everything is good but I was wondering why commercial licenses require an airbrake certificate and what you are expected to know to get that certificate. Is that something that I need to know? The manual mentions checking the air dryers annually and greasing the brakes. Someone advised me to watch the air pressure gauge to be sure that I am not loosing too much to leaks. Is there more?

I keep my rig under a roof rust should not be much of an issue.

Thanks!

Groover,
Well Sir, air brakes, the components that are used to make up the entire system, are phenomenally different than their brothers, Hydraulic brakes. Brakes are brakes, THEY SLOW OR STOP YOU, but how they're applied, what makes them work, things that you SHOULD know for use, application, maintenance, problems, etc. are quite a bit different than hydraulic ones.

In all reality, if you don't know that much or, almost nothing about your air brake system, my first bit of advice would be to get on the net, look up anything that would pertain to the system itself and, how they work and all that. Telling you to "check your slack adjusters" to a person like yourself, is like telling a person who knows nothing about computers, TO WRITE A PROGRAM FOR ONE.

There's quite a bit to air brake systems. It all starts with an air compressor, attached to the engine, that's gear driven internally. That compressor, basically is just like any home air compressor. Next in line is what's called a governor. It does, what the name implies. It controls the compressor to turn on, and, shut off. Those terms incidentally are termed, "Cut in and Cut out" pressures.

Since COMRESSING AIR causes heat, it will also cause moisture or water to develop in the system, NOT GOOD! So, next in line is what's called the AIR DRYER. Again, it does what the name implies. It, through one or two filters (some have one and some, two) dries the air, prior to it being sent out and delivered to the next phase, THE STORAGE TANKS.

The storage tanks are where all your built up air is held, until needed.

OK, that's the basics of the system. Now, as for your brakes. You have what's called a "treadle valve" for a brake application valve, under the brake pedal. When you step on it, you are allowing air, from the air tanks, to travel through that valve, through some lines, through other fittings and lines, through ABS systems (about 90% of the coaches now days have anti-lock braking systems integrated into them) and, into a final destination, what's called BRAKE CANS.

Now, those brake cans receive the air, and through mechanisms inside them, convert that to mechanical movement, to apply the brakes. Most of the air brakes in todays coaches are actuated by what's called an "S" cam. Basically, there is an axle, mounted right in the middle of the "S". As that axle turns, those portions of the S, rotate. When it rotates, there's little rollers that follow the S curves, and, those are attached to the brake shoe ends. Obviously, when the rollers follow the curves of the S, they travel outward which, in turn, pushes on the brake shoe ends which, in tern expand, and applies the shoes against the drums, neat huh?

That's the basics of how the brake systems work. There's a whole lot more to the system(s) but, that's the basics. Now, one more thing, INSIDE the REAR brake cans ONLY, are mounted some seriously strong, gigantic springs. Those springs are also what's used to apply the rear brakes. But, they don't apply them when your driving the coach. They are held back via a super large diaphragm and, a ton of air pressure.

But, when you park your coach, and pull that little YELLOW button on the dash or, where ever it's mounted, what you are doing is, releasing all that air, that's holding the diaphragm, which is holding the brakes in the OFF POSITON, to a allow those seriously large springs to apply those brakes.

By law and DOT rules and regs, parking brakes can only be applied and held on, by MECHANICAL MEANS! They cannot be applied and held on by air or in the other brake systems, hydraulics.

So, that's the basics of how your air and brake systems work.

As for maintenance, well, I could write another book here but, suffice to say, there's really not much. They're pretty self sustaining. You've been told to check to see IF you have slack adjusters. "Slack Adjusters", AGAIN, are just what the name implies. They basically take any SLACK out of the application system.

In hydraulic brakes, there are adjusting "Stars" inside the brake drums that can be rotated or, adjusted, to expand the shoes so that they are almost, if not actually touching the drums. That's done so that there's very little brake pedal needed to apply the brakes.

Well, the slack adjusters, used in air brake application, are the same thing. They basically "self adjust" to take up slack, when the brake shoes begin to wear which, causes a larger gap, between them and the drums. If that happens, your shoes travel farther out to come in contact with the drum and, in order for that to happen, you need more air and consequently, more pedal and, your brakes are not as efficient and effective either.

So, those slack adjusters are fairly important. Now, back to maintenance. One of the important things to check on a somewhat frequent basis is, check for moisture in the tanks. Sometimes, moisture gets past the air dryer and, accumulates in the bottom of the air tanks, not very often, but, it can happen, from time to time.

About 99.9% of your air braked coaches come with lanyards, attached to bleeder valves, mounted to the bottom of the air tanks. Not all, but most. Once you know where those are located, you can pull on them to see if any moisture is spit out the bottom of the tanks. I've pulled my a few times and, nothing has ever come out but, dry air.

On the S-cam shaft housing, from the brake cans to the brakes, is a lube fitting, that's used to lube that shaft and rotational points. You lube those every time you lube your coach. There are also lube fittings on the slack adjusters. Again, those are lubed at the same time. But, be frugal with the grease on both of those fittings.

As for the air dryer. Those are quite often, a neglected but, important part of the air system. Some guys on here, are capable of doing the required maintenance on them and, the replacing of the filters. In many of them, like mine, the air system has to be disconnected from them and, then they are un-bolted from their mounting position and, serviced on the bench. It's not all that hard to do that. On ones like mine, you DEFINITELY have to remove it to service it.

Now, how often does that need to be done?? Well, normally about every couple of years, plus or minus. I'm not sure what the actual, written maintenance schedule is, I just know my own maintenance schedule and, when things are in need of service. Those filters inside the air dryer, do get quite contaminated with dirt, debris, corrosion, and more so, it pays to get it serviced so your air system can work at it's prime efficiency and, you have waaaaaaaaaaay less chance of goofing up all the little valves and mechanisms in the air/air brake system.

Well, I'm sure you're quite tired of reading at this point. Hope I've helped here. There's a whole lot more to what I told you. I've given you, in comparison, one small paragraph of a book about the air system and air brake system.
Scott

FIRE UP wrote:

Groover wrote:
I have driven my DP about 20,000 miles so far and everything is good but I was wondering why commercial licenses require an airbrake certificate and what you are expected to know to get that certificate. Is that something that I need to know? The manual mentions checking the air dryers annually and greasing the brakes. Someone advised me to watch the air pressure gauge to be sure that I am not loosing too much to leaks. Is there more?

I keep my rig under a roof rust should not be much of an issue.

Thanks!

Groover,
Well Sir, air brakes, the components that are used to make up the entire system, are phenomenally different than their brothers, Hydraulic brakes. Brakes are brakes, THEY SLOW OR STOP YOU, but how they're applied, what makes them work, things that you SHOULD know for use, application, maintenance, problems, etc. are quite a bit different than hydraulic ones.

In all reality, if you don't know that much or, almost nothing about your air brake system, my first bit of advice would be to get on the net, look up anything that would pertain to the system itself and, how they work and all that. Telling you to "check your slack adjusters" to a person like yourself, is like telling a person who knows nothing about computers, TO WRITE A PROGRAM FOR ONE.

There's quite a bit to air brake systems. It all starts with an air compressor, attached to the engine, that's gear driven internally. That compressor, basically is just like any home air compressor. Next in line is what's called a governor. It does, what the name implies. It controls the compressor to turn on, and, shut off. Those terms incidentally are termed, "Cut in and Cut out" pressures.

Since COMRESSING AIR causes heat, it will also cause moisture or water to develop in the system, NOT GOOD! So, next in line is what's called the AIR DRYER. Again, it does what the name implies. It, through one or two filters (some have one and some, two) dries the air, prior to it being sent out and delivered to the next phase, THE STORAGE TANKS.

The storage tanks are where all your built up air is held, until needed.

OK, that's the basics of the system. Now, as for your brakes. You have what's called a "treadle valve" for a brake application valve, under the brake pedal. When you step on it, you are allowing air, from the air tanks, to travel through that valve, through some lines, through other fittings and lines, through ABS systems (about 90% of the coaches now days have anti-lock braking systems integrated into them) and, into a final destination, what's called BRAKE CANS.

Now, those brake cans receive the air, and through mechanisms inside them, convert that to mechanical movement, to apply the brakes. Most of the air brakes in todays coaches are actuated by what's called an "S" cam. Basically, there is an axle, mounted right in the middle of the "S". As that axle turns, those portions of the S, rotate. When it rotates, there's little rollers that follow the S curves, and, those are attached to the brake shoe ends. Obviously, when the rollers follow the curves of the S, they travel outward which, in turn, pushes on the brake shoe ends which, in tern expand, and applies the shoes against the drums, neat huh?

That's the basics of how the brake systems work. There's a whole lot more to the system(s) but, that's the basics. Now, one more thing, INSIDE the REAR brake cans ONLY, are mounted some seriously strong, gigantic springs. Those springs are also what's used to apply the rear brakes. But, they don't apply them when your driving the coach. They are held back via a super large diaphragm and, a ton of air pressure.

But, when you park your coach, and pull that little YELLOW button on the dash or, where ever it's mounted, what you are doing is, releasing all that air, that's holding the diaphragm, which is holding the brakes in the OFF POSITON, to a allow those seriously large springs to apply those brakes.

By law and DOT rules and regs, parking brakes can only be applied and held on, by MECHANICAL MEANS! They cannot be applied and held on by air or in the other brake systems, hydraulics.

So, that's the basics of how your air and brake systems work.

As for maintenance, well, I could write another book here but, suffice to say, there's really not much. They're pretty self sustaining. You've been told to check to see IF you have slack adjusters. "Slack Adjusters", AGAIN, are just what the name implies. They basically take any SLACK out of the application system.

In hydraulic brakes, there are adjusting "Stars" inside the brake drums that can be rotated or, adjusted, to expand the shoes so that they are almost, if not actually touching the drums. That's done so that there's very little brake pedal needed to apply the brakes.

Well, the slack adjusters, used in air brake application, are the same thing. They basically "self adjust" to take up slack, when the brake shoes begin to wear which, causes a larger gap, between them and the drums. If that happens, your shoes travel farther out to come in contact with the drum and, in order for that to happen, you need more air and consequently, more pedal and, your brakes are not as efficient and effective either.

So, those slack adjusters are fairly important. Now, back to maintenance. One of the important things to check on a somewhat frequent basis is, check for moisture in the tanks. Sometimes, moisture gets past the air dryer and, accumulates in the bottom of the air tanks, not very often, but, it can happen, from time to time.

About 99.9% of your air braked coaches come with lanyards, attached to bleeder valves, mounted to the bottom of the air tanks. Not all, but most. Once you know where those are located, you can pull on them to see if any moisture is spit out the bottom of the tanks. I've pulled my a few times and, nothing has ever come out but, dry air.

On the S-cam shaft housing, from the brake cans to the brakes, is a lube fitting, that's used to lube that shaft and rotational points. You lube those every time you lube your coach. There are also lube fittings on the slack adjusters. Again, those are lubed at the same time. But, be frugal with the grease on both of those fittings.

As for the air dryer. Those are quite often, a neglected but, important part of the air system. Some guys on here, are capable of doing the required maintenance on them and, the replacing of the filters. In many of them, like mine, the air system has to be disconnected from them and, then they are un-bolted from their mounting position and, serviced on the bench. It's not all that hard to do that. On ones like mine, you DEFINITELY have to remove it to service it.

Now, how often does that need to be done?? Well, normally about every couple of years, plus or minus. I'm not sure what the actual, written maintenance schedule is, I just know my own maintenance schedule and, when things are in need of service. Those filters inside the air dryer, do get quite contaminated with dirt, debris, corrosion, and more so, it pays to get it serviced so your air system can work at it's prime efficiency and, you have waaaaaaaaaaay less chance of goofing up all the little valves and mechanisms in the air/air brake system.

Well, I'm sure you're quite tired of reading at this point. Hope I've helped here. There's a whole lot more to what I told you. I've given you, in comparison, one small paragraph of a book about the air system and air brake system.
Scott

Ava wrote:
If you do not have air brake certification on your drivers license in Canada you are violating the law. I have to assume it is the same in the U.S.