Even P buses have bad days!

[mbulriss]

Country music act Lady Antebellum didn't make it all the way to Texas Stadium this morning for the upcoming ACM show in Dallas. Turns out, P buses can burn down real good also. Article said "tire caught on fire".

[davidbrady]

There's more over here. My speculation is that it was a dragging brake caliper that caused the heat that caused the blow out that fueled the fire. The older style Prevost disc brake has a rubber boot covered sliding pin caliper design. The rubber booties disintegrate exposing the pin to the elements. Rust and corrosion sets in preventing the brake caliper from releasing. The solution is to keep the pins lubricated and the booties in good shape, or upgrade to the latest calipers.

I'd say it pays to get out once in a while and shoot your wheel assemblies with an IR thermometer.

[rrueckwald]

Never thought of that. Good idea. Now I have to remember that.

You see, I have a theory that memory cells reside in hair pigment. I'm in deep trouble. Have to remember to put it on my checklist....

[mbulriss]

(04-16-2015 20:53)davidbrady Wrote:  There's more over here. My speculation is that it was a dragging brake caliper that caused the heat that caused the blow out that fueled the fire. The older style Prevost disc brake has a rubber boot covered sliding pin caliper design. The rubber booties disintegrate exposing the pin to the elements. Rust and corrosion sets in preventing the brake caliper from releasing. The solution is to keep the pins lubricated and the booties in good shape, or upgrade to the latest calipers.

I'd say it pays to get out once in a while and shoot your wheel assemblies with an IR thermometer.

These comments above about excessive hub heat coincide with my first casual thoughts about the blow out and subsequent fire. However, at the Lone Star Birds rally over the weekend, one of the members that recently purchased a P bus H3-45 pointed out another possibility. He noted that right over the tag axle on the passenger side, there is a battery bank. His suggestion was that a normal road hazard (or old age) blow out could have flung a steel belt around in there, ripping and shorting some battery cables, thereby causing some serious arcing and a resulting fire. It's certainly another plausible theory. It also gives me pause to remember that the house battery bank on most wide bodies is very close behind the tag axle tire on the passenger side also, close enough to generate lots of heat evaporation on the leading batteries in the trays (at least that is the seeming affect on my bus). Because of that, I have recently insulated the area in front of the battery slides to try and cut down on the heat transfer. As a result of this discussion, I think I may have to take another closer look at how to further protect the cables that hang on the back side of the battery bank.

BTW, I do agree with the IR thermometer suggestion and carry one to randomly check hub and tire temps on long runs. Just replaced the battery in it last weekend.

FWIW,

[davidbrady]

Mike,

Excellent info. The guys over on POG were also talking about this bus fire. Along with the two causes mentioned in this thread they add the possibility of a parking brake not fully releasing and the possibility of lack of lubricant in the hub. Prevosts use parking brake canisters on both the drive and the tag wheels. The poster suggested doing the normal DOT leak down air brake test with the addition of walking around the bus listening for air leaks; of course, with the bus securely chocked to prevent rolling. Basically, chock the wheels, start the engine, build air pressure, wait for the air dryer to spit, turn off the engine, release the parking brakes, walk around listening for hissing sounds, come back inside and note the air gauge pressure loss which should be no more 2 psi in one minute.

How many of us do this pre-trip inspection test on every trip? A parking brake canister can have a slow leak such that it doesn't quite release and the brakes drag causing heat and a fire.

[cmillsap]

(04-19-2015 00:26)rrueckwald Wrote:  Never thought of that. Good idea. Now I have to remember that.

You see, I have a theory that memory cells reside in hair pigment. I'm in deep trouble. Have to remember to put it on my checklist....

HaHa Ron. Too funny. Carrying an IR thermometer can also serve another purpose. Battery banks should be shot with one periodically. When a battery starts to sulfate, its temperature will start to rise. Using an IR thermometer to check your battery temps can reveal a battery about to go bad.

[patticake]

With all this discussion on this subject, do you really think a driver of a tour bus does anything other than drive. I know they should, and it is their responsibility(CDL), but, do they do it.

[davidbrady]

Word is that the Antebellum fire was caused by: "oil seal on the hub failed, and the bearing overheated and caught fire, mostly happens on trucks and buses that have the fancy hub caps that cover the hub seal, poor pre-trip on the driver's part", as reported on the TMZ site.

I had leaking stemco hub caps on my tag axle. While this isn't the leaking hub seal in question it is yet another leakage point. When I bought my bus in Kamloops, BC and stopped for service at Vancouver the techs spotted it. They said Prevost went to a new style stemco hub cap. Of course this is a separate item then the hub seal, but any leaks should be attended to. Here's a pic of the newly installed cover, note the larger red breathing button. There's a fill port on the side of the cap; don't try to remove the red breather:

[cmillsap]

I have replaced every hub seal on my LXi. The bus sat in the Florida sun on the POs resort site for awhile and baked and dried out the seals. They weren't leaking when I bought the bus. But after exercising the bus cross country. the leaks began to show up one by one, so I just replaced them all.

Chuck

[davidbrady]

So, what's wrong with the photo I posted in post 8?