Alert !!!!/ Toad Air Brake Tn rally

[Jon Wehrenberg]

This is a place for Peter to jump in and help. It is my understanding the assembly that attaches to your bus receives air pressure only when the service brakes are supplied. Its purpose is to function as a pass through device when everything is working perfectly. When the toad breaks away however, it will break the air line from the bus to the toad so the bus mounted device functions like a propane tank valve and shuts off air flow when it senses the line to the toad is now broken. That preserves the bus braking system and is a safety device.

I am presuming your broken fitting was between this device and the bus braking system.

The device on the toad serves to create vacuum via pressure venturi and it is that vacuum that keeps your power brake booster in a negative pressure condition to provide power assist when the brakes are applied. Additionally that device has a small internal air pressure storage tank to apply the toad brakes in the even of a breakaway. When the toad is connected to the bus and all is operating normally, your air brake pressure on the bus is also supplied to the toad to operate the toad brake pedal via the small air cylinder attached to the brake pedal.

If the system, as I described it is correctly installed it is unrelated to the bus air system pressures and it may be just a coincidence you are experiencing problems reaching normal pressure. At the pressures you describe you will not even be able to lift the front of your bus, and the rear will be marginal.

[0533]

This is a place for Peter to jump in and help. It is my understanding the assembly that attaches to your bus receives air pressure only when the service brakes are supplied. Its purpose is to function as a pass through device when everything is working perfectly. When the toad breaks away however, it will break the air line from the bus to the toad so the bus mounted device functions like a propane tank valve and shuts off air flow when it senses the line to the toad is now broken. That preserves the bus braking system and is a safety device.

I am presuming your broken fitting was between this device and the bus braking system.

The device on the toad serves to create vacuum via pressure venturi and it is that vacuum that keeps your power brake booster in a negative pressure condition to provide power assist when the brakes are applied. Additionally that device has a small internal air pressure storage tank to apply the toad brakes in the even of a breakaway. When the toad is connected to the bus and all is operating normally, your air brake pressure on the bus is also supplied to the toad to operate the toad brake pedal via the small air cylinder attached to the brake pedal.

If the system, as I described it is correctly installed it is unrelated to the bus air system pressures and it may be just a coincidence you are experiencing problems reaching normal pressure. At the pressures you describe you will not even be able to lift the front of your bus, and the rear will be marginal.

I agree that its time for Peter to get in and help. To answer your second question about the place where the fitting broke, it broke at the (AFO) valve and the (AFO) tank, not the bus tank. I cannot speak to the rest, but it all sounds right.

[Jerry Winchester]

Jon,

I also don't understand where the air could come from unless the brakes were activated. The system they installed for us worked perfectly during the 1600+ miles we have driven since it was installed.

I can also say the LEDs show up well mounted on the hitch and in direct sunlight they are visible, but not like they are at other times.

I'll inspect my installation next trip out to the hanger.

JDUB

[smibrake]

Jon, Bruce and others,

Let me first address the air assembly on the coaches. The AFO keeps the coach within the FMVSS #121 regulation because of the addition of the air tank and relay valve assembly which are added during the installation. Bruce was able to hear air while the engine was running and his foot was NOT on the brake because the relay valve was no longer attached. Air Force One uses the "metered air" to determine how much "tank" air to release to the brake system. The bus brake system operates the same way. The treadle (brake pedal) meters air to the relay valve assemly, which in turn opens and closes the relay valve that uses tank air to apply the coach brakes. The flow protection valve on the other side of the AFO tank kept him from losing all the air, that is why we add it. There was an open flow on the output side of the tank because the relay valve was apparently hit by part of the "bus box" when the bus was dropped all the way. The flow protection valve kept him from losing all the air which is why it was perfectly safe to drive the coach. It was noisy, but still perfectly safe. While it is very unfortunate, it does demonstrate the "engineered in" safety of the Air Force One. If, for example, an air brake system that simply tapped into the air lines to the coach brakes had an open flow, the coach brakes would not function properly. Using our approach, even in a catastrophic event such as this, the bus brakes operated normally. Although the air was low and fluctuated, it stayed within operating range the entire time he was driving.

Now for the engineering of AFO. Brent and I created Air Force One almost 4 years ago. The original design was tested for over 9 months with 20 coaches. We used the feed back from the installers and the testing to create the product you have. At this time there are hundreds of installations done each month all over the country. To date, there has not been one car nor one coach in which we were unable to install the AFO product. We also have three rally teams and over 900 dealers. There are literally thousands of AFO's on the market and most of them are installed with wire ties under the hood. Bruce is correct, his is tied to wires, as is often the case. The use of wire ties makes it easier to service the car if it becomes necessary. In Lloyd's case the unit is screwed to a flat plate in his Jeep. In Will's case, I believe the unit is wire tied to an area near the master cylinder. The point is, no two makes of cars are the same and each install is handled accordingly. The plastic cover that Bruce is talking about should not be loose. From memory the unit is not touching the cover and this should not be causing a problem. There are three posts (two in the back and one on the driver’s side) that the cover snaps into. The oil cap holds the cover in place on the passenger side. While every effort was made to ensure the cover was replaced properly, it is possible that I missed a post or did not push it down completely. In any case, I do not think it should be a problem to snap it down.

As for the Vue and the other problems, they should not be related to the AFO. This sounds like a situation related to the brake switch or the circuitry related to it. However, anything is possible. With Bruce’s car, the brake switch does not operate when the key is not completely on. In this case we must use a pressure switch to control the LED lights. Since we used a pressure switch, we did not attach anything to his brake switch.

I also want you all to understand that as a rally team, we have installed over 250 systems at rallies since 1/1/2008. It is true that the hours are long, but we are completely accustomed to the work and that is no excuse for not doing a job right. We take pride in our work and our products and we are very focused on customer satisfaction. The problem Bruce had could have happened any time and was related to the placement of the tank assembly under the coach.

I want to offer each of you that had an install the opportunity to have your system inspected by one of our Tier One or Tier Two Dealers. All you need to do is call me and I will see who is closest to each of you. We do not have 100% coverage with this level of dealer, but we will do what we can.

I think it is also important to understand that if there were a problem with any of the other installs, it would have shown up by now. I hope that this helps you understand the installation and operation of the Air Force One brake system. Please post more questions and I will be glad to address them.

Peter Schuck
President

[Jon Wehrenberg]

Peter, Thank you. Can you post an accurate systems schematic, detailed sufficiently to illustrate your explaination? I may have misunderstood your explaination at the rally and was of the opinion you were taking air that goes to the brake chambers for the system, but it sounds like you are using metered air from the foot treadle instead. Is this correct?

I am still trying to get my arms around why he had air flow with no brake application. Any sound of escaping air is a signal to me to stop driving, and I am presuming the bus air compressor is operating 100% of this time.

[0533]

Peter, Thank you. Can you post an accurate systems schematic, detailed sufficiently to illustrate your explaination? I may have misunderstood your explaination at the rally and was of the opinion you were taking air that goes to the brake chambers for the system, but it sounds like you are using metered air from the foot treadle instead. Is this correct?

I am still trying to get my arms around why he had air flow with no brake application. Any sound of escaping air is a signal to me to stop driving, and I am presuming the bus air compressor is operating 100% of this time.

Hi Jon,

Peter did a very good job explaining how his system works. Its gratifying to have the owner step up and offer his input and stand behind the product. In no way am I saying his product does not work, or should not be considered by other POG members, it is simply a matter of my field experience and a hope to create a dialogue with POG members and Peter in an effort to make a better mouse trap.

Jon brings up a point about the continuously escaping air while I was driving from Amelia Island to Jacksonville Prevost. I monitored both the main and backup air systems for the entire 50 mile trip and they fluctuated back and forth by about 5 to 20 lbs from normal, (Normal for me is 100-133) (abnormal 85-105) both sides. I do wonder though if air was bleeding off the entire ride could this have had any affect on the failure of my Air Dryer??? The problem in this is when the Air bags were changed out at Prevost, they really give the air sytem a workout pumping them up, deflatting them many times checking for leaks etc, placing some extra stress on the Air Dryer, but in the end it would not blow off and the pressure was above 145, at least the bags didn't leak.

There was also one other minor, very minor damage when the valve was sheered off, and I should have done something about it at Prevost. When the valve dropped down around the drive shaft with the black Air Lines attached one line rubbed up against the shaft for the 50 mile ride, and was left with a small groove in the plastic. I will have to change this line when I have the time for safely purposes.

The bottom line is that I am happy to get rid of the big BLUE OX and just plug and play. One additional thought for Peter: When one takes off the tow bar assembly to stow it away it would be nice to get 2 extra plastic caps for the air lines to keep them from the Wx, dirt and dust extra.

Thanks Peter for introducing us to your creative ideas and for standing behind your products. Now I bet you wished that you had brought your fishing pole.

Bruce

[smibrake]

Bruce,

Thank you for being so understanding and patient.

It is safe to assume that the air pump was running often. Probably not continous but very often. I rebuilt my air dryer the part of the year and was amazed at how it works. The biggest villian is this white milky sludge that is caused by a mixture of air/water/oil. The pop off can get "stuck" because of the build up. In Bruces case, his pop off was stuck closed. In my case it would stick partially open. The air pump is a mechinical pump that is virtually impossible to wear out. I would imagine that if you looked at that air dryer in Bruces bus you would have found the sludge, it is just a natural by-product of drying air.

I will try to locate a .pdf of the "plumbing" for hte AFO and post it this afternoon. Basically, the AFO tank is "spliced" into one the feed lines to the bus air tanks with the flow protection valve on the input side of the tank. The treadle air is spliced in the 3/8 air line that goes between the quick release valve (e-brake) and the service brake relay assembly.

Here is how it works:

When you park the air is removed from the chambers which allows the spring to fully apply the brake (i.e. park brake). When you release the brake, air is allowed into the chambers which pushes the spring off. When you apply the treadle, air must be removed from the spring brake side of the chamber while at the same time being allowed into the service brake side. This is rather difficult to picture in your mind but a fairly simple process.

To be as safe as possible using the air on the bus, we tap in after the bus service air but before the e-brake air, if that makes sense. This is metered air but the service brakes have already used it so brake timing from front to rear is not changed more than one or two pounds. If we simply grabbed the air from the service relay as many do, brake timing from front to rear would be changed drastically. Brake timing is the time that passes between the front brakes coming on and the rear. If the timing is changed too much abnormal wear can occur on the fronts since the rears are delayed by a lack of air.

By adding the AFO tank and relay assembly, brake timing is preserved and catastrophic events are avoided.

I hope this helps you understand the system. I will look for the .pfd after church.

Pete

[Jon Wehrenberg]

"To be as safe as possible using the air on the bus, we tap in after the bus service air but before the e-brake air, if that makes sense."

No it does not make sense. But that doesn't mean you are incorrect, it just means I still haven't grasped it. I always treated the air supply to the emergency brakes which is "on" while in motion as a totally separate system from service brake air.

I would have guessed you would tap in at the relay valve to the tag axle. I am still unclear how the minimal air flow to your system would have a measurable impact on the timing between the front and rear.

[smibrake]

When you are driving the quick release valve is turned off. This is controlled by the e-brake button in the coach. The quick release valve operates much like the service relay valves but in reverse. The air that comes from the front of the bus does not apply the brakes nor is used set the e-brake. The air from the front simply controls (meters) the air from the tanks. If you tap into the air at the service relay or at the air cans then more air must be sent from the treadle before the relay "cracks" the air from the tank to apply actually apply the brakes.

Brake timing is the time that passes before the rear brakes engage after the fronts. Fronts brakes do a higher percentage of braking in all vehicles. If the timing is tampered with then premature brake wear will occur on the front brakes. According to the engineering department at Bendix, tapping into the air at the service relay will cause the crack pressure to increase by several PSI. If the standard crack pressure 8 - 10 psi and you take the air from the service brake for a tow brake system then the crack pressure will increase up to 15 - 17 psi. It does not effect the brake effort supplied at the wheels, only the timing of when they apply.

With the e-brake off air enters the system and pushes the spring which releases the brakes. In order for the treadle to operate the brakes it must work in conjunction with the spring brake valve. Metered air is sent the main relay assembly to put air on the "non-spring" side of the brakes. In order for the brakes to apply air must be removed from the spring brake side. The two systems work together. It is true that AFO uses the metered air that goes to the spring brake side but according Mike Oneal at Spartan and engineers at Bendix, this will only slightly impact the timing of the front and rear brakes. Because the metered air first goes to the main relay assembly and cracks the valve, no air is lost to this part of the system. The metered air is used in the main relay assembly and then passed to the spring brake. The AFO is tapped into the 3/8 line that connects the main relay assembly and the spring brake assembly.

It is true that air could be taken from the tag brakes and not impact timing. However, depending on the year and the make, tag brakes are typically set up to brake 20% - 40% less than the drive axle. Again, it is certainly something that is done but I do not know of a tow brake system that is designed to use tag air. The end result would be a tow brake that did not function as it should Because the air pressure was lower than it is engineered to receive.

The service relay valve is very similar to the AFO relay valve. Tank air comes into the valve and is metered by the treadle air. When Bruce lost his relay valve it did not impact the timing any more or less than if the valve had remained attached. However, since it was not attached to the AFO tank, the tank air was compromised. The air pump on the bus is capable of keeping it up to drive it in, that is a DOT regulation. The flow protection valve on the tank protected the air so it did not bleed out. Again, this safety is engineered into the AFO on purpose. Up to this event, we have never had any feed back about the function og the flow protection valve. Now we know it works and protects the coach as necessary.

I have heard for a few of the others and all say that the system works great. Will tows that 2500 Hemi Ram and feels that he stops substantially easier with the AFO. He said that in normal stopping the brake does not apply. As he stops just slightly harder than normal, the AFO applies the brakes in the truck.

I tried to simplify the operation of air brakes. It is difficult to understand and even harder to explain. Bendix has some great information available on air brakes. I will get Brent to look for a link to their site and post it Monday if he can find one.

Pete

[Jon Wehrenberg]

Thank you.

Now explain the escaping air sound when the brakes were not being applied.

From the treadle the air flow, when the treadle is operated goes to the relay valve and then to the respective brakes. There is no air flow in the system until and unless the treadle is operated. Or am I mistaken?

Also, just out of curiosity, if you prefer to not use the tag axle, what about front axle air to the service brakes?