Caroni Flail Belt Failure

[davitk]

Off topic a bit, but the idler pulley on my Dodge pickup has been failing, (me bad, I have known for three weeks) allowing my serpentine belt to overheat and shred during rush hour this morning. The belt broke the washer fluid pump and lacerated the upper and lower radiator hoses. 500 bucks plus a 79.00 tow plus an unplanned vacation day

 

[sunspot]

Ouch.
So you escaped the wraith of the Chinese and Italian belt deities but Dodge bit you.

 

[Eagleview]

Ummm, I think Iron Horse meant resonanance, but I'm just guessing.

My bad , meant to say "Critical Speed" .


Island Tractor.// I would see if you can drill out the eyes a bit larger if you can without weakening them . 3/16" or 1/4" prefferably .You could then use a small clevis with a hardened pin , or a small hardened 'D' shackle to attach the chain or maybe 2 pieces of 3/4"X1/8" flat bar held together in a vice and drilled so that the holes are exact . They would then be put either side of the eyes and a hardened pin or grade 8 bolt put through them ( i think i would use this option myself) . No matter what you use it must be fail proof , if it fails your belts are toast .

 

[Reg]

I also found the Gates B43 at RocklandAuto dot com for a $7.35 each (about $3 less than McMaster-Carr). They are described as "GATES Part # B43 {Hi-Power II Belt B 21/32" x 46"} Category: Classical Section Wrapped V-Belt" which sounds right.

Now, I need to find a bigger spring or a solid threaded link. A new threaded link would be nice but then I'd need to deal with an attachment point. Maybe using a small section of chain to replace the existing spring would be easiest. Is there any reason not to just reinforce the existing spring by wrapping wire tightly through it?

Here's a clue;
Find a global arborvitae about 4ft across, say 25 years old.
Back up over it with your mower lifted and running, lower the mower, just before it gets to the ground the chances are the 5 or 6 inch diameter trunk will rip right out of the ground and jam the mower.
Hear any belt slip (Squealing) just before the tractor stalled ?
How about when it was loading down while munching on the mid section ?
Right, didn't think you would.
Increasing the belt tension is only going to add side load to the shaft bearings and lead to OTHER problems.
Dunno why we're so ready to assume that Caroni don't know what they're doing here, that their designers are idiots, etc., but I for one ain't about to re-engineer this thang on a whim.
Belts slip, we know that much.
We know it is a GOOD thing that belts slip and absorb shock loads instead of passing forces back up to more expensive parts.

 

[Reg]

Agri-Supply is sending me a new set of belts "for testing".
I will mark the originals before taking them off so they can be aligned to each other for any subsequent testing.
I will probably try shifting them 120 degrees just to see what difference it makes.
I will also get a fish (weighing) scale to measure the force on the belts at the roller, which is SOME representation of tension.

There is a lever effect; but right now the cover is on, it is bug time out there and I'm not remembering whether the lever divides or multiplies the force of the spring. Whichever, I'll be sure to measure it at the roller anyway and see what I can find on the Gates site re recommended tension.

 

[Reg]

I just reviewed Island Tractor's pics.
Thanks, I had forgotten the layout.
The lever in fact multiplies the spring's force, by about 1.5 at a guess.
Without trying REAL HARD at the time I remember casually pushing on the roller one time and noting that it didn't budge. I'll get the fish scale and see if I'm strong enough to budge it after my Wheaties tomorrow.

 

[IslandTractor]

Hear any belt slip (Squealing) just before the tractor stalled ?
How about when it was loading down while munching on the mid section ?
Right, didn't think you would.

I have stalled the tractor occasionally while mowing with the flail. I don't believe I've ever heard belt squeal. However, there was quite a lot of what I think may be belt debris (fine fluffy stuff that did not appear to be vegetal in origin) at the bottom of the belt cover when I took it off this weekend. That was only about 5 mowing hours since I last took the cover off. Just for reference what I mean by quite a lot is enough to half fill a spray paint can cap...it is light and fluffy so it weighs next to nothing. Again, I did not do any careful inspection but it seemed suspicious to me that it was almost all grey brown in color and that I'd only been mowing green grass the day before. See photos. I'd love it if someone told me it was just fine mowing crap and not belt related.

I think I will first try to max out the existing spring adjustment. Then I will try a solid replacement for the spring but will be careful not to over tension it. I did get a infrared thermometer (thanks Amazon) so I should be able to tell if there are any changes in belt cover temperature. I just read IronHorse's new suggestion regarding strength of the spring replacement. I'd already picked up some 1/8 inch smooth steel rod that I intend to cut and bend some v hooks onto the ends to serve as a spring replacment. I may or may not get around to doing the switch this weekend but will report back. I could not find a more powerful spring in appropriate size at HD and don't know if I'll have time to track one down before the weekend but that is the other route to consider.

 

[Eagleview]

I just thought of a better way to do the task . A short piece of pushbike or small motorbike chain and two joiner links , the links would have 1/8" hardened pins and would fit both eyes .

 

[IslandTractor]

I just thought of a better way to do the task . A short piece of pushbike or small motorbike chain and two joiner links , the links would have 1/8" hardened pins and would fit both eyes .

I thought of that but haven't been near a bike shop. Maybe I should. I had figured that the 1/8 inch unhardened steel was probably up to the task. The original spring is 1/8 inch for starters. When I looked at the spring forces permitted for even bigger springs at the hardware store it seemed that I needed only about 100-200lbs of force to exceed the original spring by three or four times. In a static set up with a pulling load (forget the engineering term) I'd think that 1/8 inch steel would suffice. 1/8 inch chain can be used for swing sets that handle about the same load or more.

 

[wstr75]

This link provides information on causes of belt heat, belt life, effects of ambient temperature changes and a bunch of other stuff relating to this thread. About 3/4 through the document, he provides statistics on how much a one degree rise shortens a belt's life. He mentions air flow through the housing and ambient temperature as two things that affect belt life. According to this guy from Gates Rubber's information, cutting grass on a 100 degree F day at wide open PTO revs with a sealed cover will significantly shorten a belt's life.

MRO Today - Think you know drive belts?

Bill in NC