Alert !!!!/ Toad Air Brake Tn rally

[Denny]

Bruce,

Don't hesitate to call Peter at Air Force One. About six weeks ago he called me and said he was sending me a new, updated tank assembly because of some problems that became apparent after all the units he sold and installed at Sevierville. I did receive the replacement and went to his recommended dealer about an hour from me and had it installed.

I did not have any problems with the first tank assembly but he wanted to replace it anyway. He needs to be made aware of your problem since this was the second time (I think) for you.

[Jon Wehrenberg]

I'm with Orren on this one. Upon seeing the picture my first question is why is the relay valve hanging down? Something is wrong if such an important component is hanging by its hoses and worse, if that gets ripped out of there by that spinning driveshaft your bus will puke air at a significant rate and your tag and drive axles are locking up.

Is that relay valve a part of the toad braking system? If so why wasn't it bolted in place?

I also carry a mixture of caps and plugs so if I have an air system leak I can stop the loss of air. I may lose a part of my braking system such as the service brake to a wheel or an emergency brake on a wheel, but at least the air is not leaking and I can drive to a repair facility. With an auxiliary braking system I would insist on having shut off valves where the installer taps into the bus. And if the installer held that relay valve in place with nylon wire ties I would seriously question the integrity of their entire product line.

Anybody that has that braking system needs to do an inspection of the system installation and add those shut off valves. Another reason why owners need to monitor the work done on the coach.

[0533]

Your picture shows a standard Bendix R-12 relay valve (with 4 port) and a pressure regulator (it doesn't permit air to pass through until a preset pressure is reached, usually 65 or 95 pounds) dangling by nylon tubing. I'm sure the howling you heard was your rear brakes engaging as the parking brakes began to set up. No low air buzzer? Just lights and a gauge? Why wouldn't the manufacturer just tee off your existing relay emergency valve? Was that R-12 added by your toad brake supplier? I carry an assortment of tubing fittings in various sizes so I can cap a line if necesary so I can get off the highway and to a service provider.

Hello Orren,

I am not nearly a well versed about this as I should be, but could I ask a few questions.

1. The Howling sound while driving off the ramp seemed to be escaping air from under the drive axle. The pressure on both dash gauges were reading 120 lbs, and no low air pressure lights or alarms were on.

When I arrived at the RV park where I leave the bus and was setting still the howling sound continued, but the air pressure began to drop until it reached 80lbs, then the howling noise stopped.

I inspected the bus carefully and did not notice any damage or heating around the brakes of the bus or the toad. I am very concerned by your and Jon's comments about the drive and tag service brakes being on while driving along at highway speeds. When my brakes are applied I see a light on the dash that shows that the brakes are on, is this light attached to the pedal and not the actual brake, and if so then why did I not see red hot brakes or even some smoke or something. I am getting increasingly more upset about this whole dam experience.

I do know that the Air Force One install taps air from the main or secondary tank, but know that it runs to the R-12 Relay you mentioned, then to a small air tank installed by AFO) then to the toad.

I think that somehow the drive train catches the line or hits the R-12 relay and severs the fitting from the R-12 to the AFO tank and the end result is that it falls onto the spinning drive shaft (PS> scrapping up against it leaving lines scraping around it, hope this does not damage this shaft).

I was under the impression from AFO that in this event there would no effect on the main braking system, but it does not appear to be so as it must be placing a stress on the entire system trying to keep the air pressure up for braking. I also wonder how effective the brakes would be in an emergency braking situation??

Finally I am not a big fan of going under the bus to fix for the second time an install that should not require any service and repair.

My plan is to raise the bus on one side, place the Prevost hydraulic jack under the jack point on the high side, go under and cut the line from the R-12 to the Prevost air tank, crimp and secure the cut line, seal it somehow and then have the entire thing removed and start over, including careful inspection of the drive shaft.

When this happened before I had Prevost Jacksonville reinstall the unit make a new fitting for the R-12 unit and place the whole thing out of the way of the drive shaft so this would not happen again. I do not feel that AFO has completely engineered this install for our buses to insure against this happening?

[Jon Wehrenberg]

The system check valves are doing their job, and the broken fitting was located so the valves could work.

However, the lines to the relay valve appear intact, but one of them had been laying against the driveshaft and it was a question of time before it would have failed. When that line let go it became another air escape point. If the remaining line was then severed you have a third air escape point.

I am surmising the relay valve is not one originally installed on your coach, but is dedicated to the aux braking system. Even at that it should have been secured to the coach in the same manner as the original equipment valves are and the fact that it is hanging and is a few driveshaft rotations away from being ripped off tells me its mounting was inadequate.

Should you have an air loss that is in a location where the safety valves will not stop the leak your braking system air pressure will drop and once it falls to around 40 or 50 PSI your emergency brakes are going to automatically apply. It can be said the installation was a good one because you were protected from a catastophic air loss, but if my interpretation of the picture is correct and your relay valve was hanging as shown and the air lines were rubbing against a spinning driveshaft as it appears you could very well have experienced brake lockup.

[0533]

The system check valves are doing their job, and the broken fitting was located so the valves could work.

However, the lines to the relay valve appear intact, but one of them had been laying against the driveshaft and it was a question of time before it would have failed. When that line let go it became another air escape point. If the remaining line was then severed you have a third air escape point.

I am surmising the relay valve is not one originally installed on your coach, but is dedicated to the aux braking system. Even at that it should have been secured to the coach in the same manner as the original equipment valves are and the fact that it is hanging and is a few driveshaft rotations away from being ripped off tells me its mounting was inadequate.

Should you have an air loss that is in a location where the safety valves will not stop the leak your braking system air pressure will drop and once it falls to around 40 or 50 PSI your emergency brakes are going to automatically apply. It can be said the installation was a good one because you were protected from a catastophic air loss, but if my interpretation of the picture is correct and your relay valve was hanging as shown and the air lines were rubbing against a spinning driveshaft as it appears you could very well have experienced brake lockup.

I never experienced a loss of pressure while at highway speeds or even while at my first stopping location (red light). Not until I got to a the rv park and applied the parking brake did the pressure start to drop below 100lbs or so. It dropped to about 80lbs then the noise stopped. I then checked the bus for damage and found the hanging valve. I then released the parking brake and backed up the bus into its slip. The air pressure never rose above 80-lbs and the noise never returned. I assumed the tank suppling air to the valve had lost all of its air and now was locked out, but now I'm guessing if I were to have gotten back up to highway speeds the pressure would increase beyond 80lbs and the noise of escaping air would have started again.

My job now is to safely remove this line and seal off the fitting or the line itself to allow me to head back to Prevost for repair.

I must say it is very unsettling to rely on after market installs on these big buses and have such a poor result.

As a pilot, I should have been more involved in this install in the first place considering what was involved (air System), I was distracted by the POG events and was not there during the actual install process.

The funny thing here is that I got rid of my ridiculous Blue OX brake at the rally for this one and now am back to square one, plus now I am chasing my tail to figure out a way to get my Bus braking back to some degree of normalcy.

[garyde]

I have only read a little regarding this thread from the beginning when some people had this system installed in Sevierville. My question , is it legal for a after market company to cut into the air braking system on these coaches? I believe Prevost has to certify their coachs for the US and Canada with their braking system as it was originally designed. Does this not create a Certification issue. Maybe this Company, Air Force One, is allowed to modify Prevosts air system and re certify but it appears they don't have a fail safe design.

[Jon Wehrenberg]

Their system duplicates and runs in parallel with the bus braking system. Other braking systems just tap into the relay valve. The fact that Bruce was able to maintain sufficient air pressure shows they are maintaining the integrity of the original braking system.

Don't overlook the fact that Prevost JAX had its hands in this also. To have a relay valve hanging by its air lines suggests to me that both parties have an equal share in failing to create a more substantial installation. I think it could be argued that it was the falling relay valve and its likely contact with a driveshaft that caused the broken fitting this time. I see the failure to adequately secure the valve as the source of this round of problems.

Based on that opinion which can be completely wrong, I suggest everybody with the braking system get it inspected to insure the valves are properly secured and if it were my coach I would add shutoff valves where the Air Force One system attaches to the coach should there still be problems with that system.

[Jim Skiff]

I spoke with Peter in Minnesota and he has re-engineered the product. He also appears to be very responsive to POG issues related to Air Force One.

I'll see if he can respond here.

[0533]

Their system duplicates and runs in parallel with the bus braking system. Other braking systems just tap into the relay valve. The fact that Bruce was able to maintain sufficient air pressure shows they are maintaining the integrity of the original braking system.

Don't overlook the fact that Prevost JAX had its hands in this also. To have a relay valve hanging by its air lines suggests to me that both parties have an equal share in failing to create a more substantial installation. I think it could be argued that it was the falling relay valve and its likely contact with a driveshaft that caused the broken fitting this time. I see the failure to adequately secure the valve as the source of this round of problems.

Based on that opinion which can be completely wrong, I suggest everybody with the braking system get it inspected to insure the valves are properly secured and if it were my coach I would add shutoff valves where the Air Force One system attaches to the coach should there still be problems with that system.

Good morning Jon,

It is a bit ironic that when I first had this problem back in April just after it was installed Prevost Jacksonville sort of scratched their heads when they saw the valve dangling down. They were not impressed by the device or the install, but more as a favor to me than anything else they repaired the broken fitting and placed the valve further away from the top of the drive shaft.

Prevost Jacksonville did not re-engineer the install or even give it much time or thought as it was not part of their planned service program.

I should have demanded that Air Force One have the entire install redone and certified that it would not or could not happen again. Frankly AFO should have done this on their own.

My bus is not designed differently than others, but for some reason has been having this problem.

The only possible difference ( I would love to hear from others who have the install) is that I have been out on the road non stop since the install traveling running up miles and ending up in all sorts of places. This is no excuse but might help better understand why the install is not robust enough to standup to the rest of the Prevost systems.

Its also possible that this one install was done differently, and the tank and valve were placed in the wrong place, too close to the drive shaft and the drive shaft well.

Today I plan on making a close examination of the failure and decide on a fix before heading back up to Prevost for repairs. I will report on my findings.

[phorner]

Bruce,

Mine failed exactly like yours: the small nipple shearing between the tank and regulator.

This has been re-engineered to eliminate the small nipple. Apparently, this has been the trouble spot. Even nipples that have been replaced have failed, which leads me to believe that it wasn't simply a batch of defective nipples in the original setup.

Good luck in your repairs. I know what a PIA it can be. The good news is that Peter will see to it that you get a replacement unit installed.