777D A/C belts problem (FKR prefix)

[Dimonsof]

Hi All.

Did anybody has had troubles with A/C belts on 777D (serial number prefix - FKR)?
We had struggled with this in Namibia since 2014, and the belt part number we were using was 213-6558.
CAT made couple updates - none of them helped.
We are now in Mali with same problems. Recent CAT update came up with some pulleys rearrangement and another belt p/# - 117-0036.

We used about 10 each of them by today, still doesn't work.

We are thinking about trying to get GATES cogged belts with same dimensions (maybe a little shorter). CAT so far keeping their head in their ..s. But we are in construction phase and can't wait few months for their decision, and West Africa is hot - couple month later it will be damn hot here.

Thanks in advance!
Dima

 

[Cmark]

I've not personally come across this, but I can see the update (REHS7192) that you have had done. They are running the back of the belt around a couple of idlers so it's not surprising the belts aren't lasting. I can't see any reason why you can't try a cogged belt.

Another suggestion is to try a belt for a mower deck. These are designed to run in weird directions around multiple pulleys. I believe they have kevlar (?) in them and the ones I have seen are green in colour.

 

[Dimonsof]

Hi Cmark.

Thanks for advice.

Part of the problem is that these 2 pulleys (where they are running the back of the belt around) are flat. And the one just close to A/C compressor - is the one where belts slides off. There is nothing that holds the belt on the pulley. I just found that 777D (AGC prefix) using different type of pulley (147-0782), and, basing on SIS picture, that pulley has kind of flat groove. Will try to order it and see if it fits and works.

Regards,
Dima

 

[kshansen]

Dimonsof, I had to look at REHS7192 to see what this setup looked like, they sure are working that belt over with all that monkey business!

I also took a look at the 147-0782, worth a try.

A couple off the top of my head thoughts. Would it be possible to add a flange to your existing pulley? Maybe tack on a 1/8 inch thick disk to the edge the belt is walking off?

Another idea. Is there enough "meat" to the pulley to machine a shallow groove on the surface the belt runs against? Thinking just a rounded bottom maybe 1/8 inch deep just enough to "encourage" the belt to stay centered.

Good luck and keep cool! Wish we could send you some it is -13ºC here this morning!

 

[Cmark]

Yes, I see what you're looking at. That grooved pulley is part of the 1299491 compressor mounting group used on early serial number AGC machines. The thing is, that same group is also used on your FKR machines, albeit with the latest flat pulley instead of the grooved pulley.

I'm guessing that your machines were delivered with the 1299491 group and this group was removed and replaced with the 3680081 compressor mounting group, which is essentially what REHS7192 is telling you to do.

I think that in order to use the grooved pulley, you would have to reinstall the 1299491 group, along with the grooved pulley. Essentially converting your machines to the early AGC spec. I'm not sure that this would solve the problem, as Cat must have discontinued it for a reason.

 

[Dimonsof]

Thanks Kshansen!
I was thinking about making groove in that pulley... We just started here, so it is temporary shop, no lathe or anything like that. The disk might be a solution if we find piece like that. We'll try.

Thanks anyway!

Regards,
Dima

 

[Dimonsof]

Yes, Cmark, machines originally were shipped with previous style pulleys and CAT changed them while assembling the trucks.

We don't have any other options yet. local CAT dealer is slower than smoke of the sh..t. Actually like any other company here - the word "urgency" doesn't mean anything.
If this trick with pulley will not work - as Kshansen said above - we'll try to find machine (lathe) shop around here and try to rework existing pulleys...

Thanks,
Dima

 

[lantraxco]

From the world of flat belts and conveyor belts, you might need a crowned pulley, a little higher in the center... I never did give too much thought to the physics but a belt will naturally try to climb the slope.

 

[Nige]

Check out Service Magazine SEPD1920 of 27/01/2015. It details improvements to the parts included in the REHS7192 procedure, including a different Part Number of idler pulley assembly - 466-1650. Depending on when the work was done it may be that the latest and greatest parts weren't used.

 

[Dimonsof]

Thanks Nige. We'll check that pulley also.

Regards,
Dima