[Tom]

The engine fan/air drive pulley has 3 belt positions, I have 3 spare AX-74 belts, These should be the ones, I am aware of the tension regulator valve above and have released the tension. belt placement is pretty simple on these 3.

On the other hand, I have the Bus A/C & the Generator below it. 2 belt positions on the pulleys. I was told that I need a BX-94 on them? Is that correct? Looking at my spares that Bill had in reserve, I have 2 belts labeled BX-93.

is there a BX-94 And bx93 combination? If so which one sit on the forward pulley position and which is on the aft?

I see that I can adjust the tension via the bolt by the generator housing. I am just really unsure about the BX 93/94 deal.

any hep is appreciated.

chip

[Archived]

if you have 93 belts than I would put them on to compressor with the tensioner you will feel if it is correct size easily I wouldn’t think you would have the wrong size left with the coach.

[Archived]

Chip,

The belts are routed outside the AC compressor and 24V alternator and inside the idler pulley.

Either size will work. It depends on where you want to position the belt adjuster under the alternator.

Here’s a trick to replacing the belts. First, it assumes the same belt size is being used. Remove the idler pulley by removing the 2 nuts that hold it down. Install the belts and replace the idler pulley. Make sure you line the idler pulley up to where it was. You can usually tell where the washers made contact with the pulley’s mounting bracket.

This happened to me once. I blame the mini air bags not coming up fast enough. They did leak a bit at the time, which probably didn’t help.

[Archived]

It’s not uncommon for one or more of the 3 belts to come off because of no aux air pressure on start up and the bellows are flat. I always make sure I have some aux air before starting. Not saying that is what caused your problem, but it happens, then other belts get jammed up.

[Archived]

Two comments. You CC owners can help out a lot if you post some photos. I doubt if the coach in question has Prevost OTR so what is needed is some photos of how CC ran their belts for their accessories.

But I disagree with Tom about aux air to keep the belts tight for start-up. Unless someone knows seated coaches have aux compressors or are leak free I strongly suspect their belts go slack between runs. From what little experience I have had as a seated coach passenger I also suspect the drivers leave the fast idle switch on at all times so when they start up their engines race right up to 1000 RPM. If anything should throw belts it would be seated coaches.

Look for an issue beyond loose belts and it could be misalignment or even a bad idler pulley.

[Larry & Diane]

Chip, my reply was specific to your coach.

Tom, I agree. My belt failure occured after checking into a campground. My guess of the problem is that the engine was still warm enough to engage the fan at start up. Of course, this would be a non issue if starting a cold engine and my leaking mini bags didn’t help. Although my minibags now stay inflated for days, I do have a habit of using the aux compressor before starting if the bags are deflated.

[AL]

With all respect to Gil on this one, If my belts were routed like that I would sure want them tight on start up. Mine look nothing like that thank goodness. With little more than 90 degrees of belt contact on a pulley I would feel very uncomfortable.

[Chip & Pam]

That is a constant problem on the CC’s with CC OTR. That bottom pulley for the alternator is just to much of a tight radious. My belts only last about 8 to 10 thousand miles before I notice them cracking. They are the ones that usually cause the problem throughing off the other belts.

Thats my next project, changing the angle of that pulley.

Those compressor belts will be 93 0r 94. depends how much adjustment you have in the lower alternator. It is not much.

[Larry & Diane]

thanks to all for the inputs and advice. I will route the BX-93 as Gil has in the picture. I have new ones on order from my local parts folks. For now I have the 3, AX-74 belts on, so we can at least move in an emergency.

the minibags and the age of BX-93 belts are what I suspect caused my problem. The bus has been camped for 3 weeks at Tyndall. We started the bus with normal expectation & got abnormal results.

I think Gil is correct, I’ll be adding a step to “Start Up” checklist to check the minibags and to start the aux compressor prior to turning the ignition key anytime the bus has sat for a period greater than 2 or 3 days.

Have great Memorial Day everyone

Chip

[AL]

Install check valve on mini air bellows and if they are not leaking they will be tight , plus make sure fittings are not leaking!!!!!!!! Install at inlet on regulator to mini air bellows…

[Archived]

It doesn’t bother me that the belts have 90 degrees of contact with the pulleys. This is common practice in the autmotive industry. I have never heard of anyone saying their belts slipped and many run these loose.

What is a problem is the amount backwards bend put on belt from the lower idler pulley. There is a debate among us CC owners as to whether we are better served with a solid or cogged belt. I use a cogged belt and have put 20,000 miles on them with no problem. Gates makes belts for this kind of configuration. Unfortunately, they don’t make one this long.

[Dick]

gil

looking at the photo of your alternator, my belt adjuster is full in and yours is only half way in. Your adjuster show thread and mine is flush. As I have found out loosening the side nut on the alternator to much and you unthread the adjuster. No fun was had trying to get it threaded back on. The biting yellow flies added more ambiance to the experience giving me a Flash back to the Mid East working on T-56-15’s

My question is: what is the adjustment spec used by CC ?

[Archived]

The position difference is because we are using 2 different belt lengths. Most adjust the belt until it no longer hits the frame past the idler pulley. That’s pretty much how most did it in the old days. There is a method of measuring belt deflection, but this guage is the way to go. Gates has a tension spec on their web page. I opt for the low end of acceptable.

http://www.amazon.com/Gates-91132-Belt-Tension-Tester/dp/B000CRDLZM

[Archived]

I’m an trying to (in an emergency) bypass the a/c compressor.

I’ve measured the distance leaving out the a/c compressor as 88.25″, where the original belt is 93″.

Does anyone know the a specific parts number for that (shorter) belt?

Thanks.

[John]

I think you can tell any parts house I need a B93 or what ever and they will know what you are talking about.

The B designates the belt V size and the numerical designation is the length.