Caroni Flail Belt Failure

[Reg]

I think it has already been established that the Caroni belts don't squeal on start up or when mowing heavy wet tall grasses, they also have enough grip to stall Island Tractor's tractor (without squealing) when the mower finds an "un-munchable" object. The same happens on mine. From this too little tension doesn't seem likely (to me) to be the problem.
I have been under the impression that the "standard" 3/8 deflection is for belts without tensioners, i.e. those that are adjusted by moving either the driving or driven pulley, alternator belts, etc.

The replacement belts that Agri supply sent me are too short, I can get them on the pulleys, but cannot get the tensioner bolt through the hole, even when really leaning on a long wrecking bar as a lever to push the tensioner roller forwards. They might work without the tensioner, the slack is probably around 1/2 inch, though I havn't measured it.
I havn't had the time to call and discuss it with them, one had a price sticker still on the cardboard sleeve - $3.9x. They didn't seem to be any sort of a matched set, i.e. the printing on one cardboard sleeve was much more faded than the other two. I'll give it one more round with Agri, then pursue it with NAPA for segmented belts.

$30 or so ?, maybe....

My approach is to "AVOID wasting energy in the mechanism".
Less tension is a possibility, less work devoted to belt flexing is another.
Carrying excess heat away is less attractive, I am MUCH more interested in not generating that excess heat.

 

[IslandTractor]

I'll do my best to make the comparison of spring tensioned vs solid tensioned as fair and pseudoscientific as possible. I'll take a break (necessary for the switch over anyway) and will document the temp before starting again. If possible I'll do some non mowing work in between. I'd love to wait another day but don't have that much time on the island this weekend. If the results are confusing I can always repeat them in reverse order another time.

One question I have is how to set the 3/8 inch deflection on the solid tensioned trial. I would presume using the longest open stretch of belt but I am not sure how much pressure to apply in looking for the 3/8 inch. Thumb pressure?

 

[Cyberroc]

it was supposed to be light hearted

oh, no harm / no foul

That was my way of saying that you did not have to point out that I was wrong, I knew that when I wrote it.

In the end, I hope this is something easy to address as this in a unit that I am highly considering as my next purchase, if I don't go with a befco.

 

[Eagleview]

One question I have is how to set the 3/8 inch deflection on the solid tensioned trial. I would presume using the longest open stretch of belt but I am not sure how much pressure to apply in looking for the 3/8 inch. Thumb pressure?

Thank you IT for offering too answer this question for all .

This is a page from my Berti catalogue , they suggest 5mm at 5kg but it has 4 belts and the pully centers are quite close , it may help , 5mm = about 1/4" and 5kg= 11lb . Distance between pullies has a big influence over deflection . If it where mine i would adjust it too 3/8" with enough thumb pressure to turn my thumbnail white . (this is a very scientific approach) but in the real world is quite adequate.

 

[IslandTractor]

Thanks Mate, I'll use the thumb capillary refill technique.

 

[Eagleview]

I new there was a correct term for it ......not .

 

[sunspot]

I'll give it one more round with Agri, then pursue it with NAPA for segmented belts.

$30 or so ?, maybe....

Do you have a part number?
I found the number for Kelvar belts but I haven't bought them so check it out for yourself first.
5H460 should be the same as B43

 

[SPYDERLK]

The replacement belts that Agri supply sent me are too short, I can get them on the pulleys, but cannot get the tensioner bolt through the hole, even when really leaning on a long wrecking bar as a lever to push the tensioner roller forwards. They might work without the tensioner, the slack is probably around 1/2 inch, though I havn't measured it.
I havn't had the time to call and discuss it with them, one had a price sticker still on the cardboard sleeve - $3.9x. They didn't seem to be any sort of a matched set, i.e. the printing on one cardboard sleeve was much more faded than the other two. I'll give it one more round with Agri, then pursue it with NAPA for segmented belts.

$30 or so ?, maybe....

My approach is to "AVOID wasting energy in the mechanism".
Less tension is a possibility, less work devoted to belt flexing is another.
Carrying excess heat away is less attractive, I am MUCH more interested in not generating that excess heat.

Segmented belts are not compatible with idlers that back flex the belt. They will be short lived due cracking at the cog roots.
I hear you about wasting energy. Unfortunately idlers do just that by the added flexing. Too bad that is the way Caroni chose to tension the belts.
larry

 

[GinNB]

Not sure of the exact belt size on these mowers, but just thought I'd mention that it's possible to replace expensive metric belts with pretty-bloody-close "standard" equivalents on flail mowers with good results. Just take a new belt to an industrial rubber belting shop and have them measure it up and get their opinion. I found that a $6 B belt was just about exactly the same size as a $60+ (forget exactly) metric belt on one mower. That particular mower takes 3. $18 vs $180, plus the cheaper belts are always in stock locally. Also, overpowering a mower in heavy cutting will burn out belts even if everything is adjusted and working properly on the mower. That's probably not a problem running compacts but some of the fellows have done that on our mowers with 80+ horsepower to play with.

 

[IslandTractor]

OK guys, here is my report on testing the spring vs solid belt tensioning on the Caroni TM1900.

I used an infrared thermometer (Mastercool MSC52224A from Amazon)to measure temperature of 1) belt cover over the top pully, 2) top pully spindle center, 3) top pully peripherally close to belt, 4) bottom pully, 5) belt temp at top dead center on top pully and 6) cover of non powered bearing on other side of the mower. The thermometer reads almost instantly and has a laser dot to show where you are measuring. All measurements were taken within a foot so the area measured was about an inch to inch and a half diameter with the dot in the center.

I measured first after mowing with the stock spring tensioning set to 3/8 inch deflection with the now famous Iron Horse thumb blanching test. I measured the deflection with a tape measure while applying thumb pressure on the forward longest belt run between top and bottom pully. (Note, there was some slight individual variation between the three belts but I standardized on the first outer belt). After running the first trial with the stock spring, I returned to the barn, and replaced the spring with a piece of 1/8 inch steel with bent hooks on either end. The belt tension was then reset at 3/8 inch just as with the spring. The break between mowings was 2 hours and I documented the belt cover temp was down to 90F before starting the second mowing.

I tried to cut adjacent nearly identical fields for identical times on the same afternoon with ambient temp in the low 80s. Both fields had been cut once this year I think in mid May. I was cutting mostly mixed grasses about 18"-30" but also cut some brush on the borders of both fields. Engine speed was kept at 2000-2100 rpm with recommended 540 PTO speed being 2500rpm (don't ask why, I just routinely mow at that speed).

After each session I immediately stopped tractor in a shady spot, shut off engine, lowered 3PT and then took cover temp followed by removal of cover (takes me only a minute or so in the field with a ratched socket) and then took the temperature measurements in the same order as listed above. All temps were measured and recorded within about 3 minutes of finishing mowing.

Despite efforts to keep the test at equal time on equal fields, in fact the stock set up spring tensioned mowing lasted just under an hour (53 min) and was in retrospect just a little easier field to mow than the one with the solid rod tensioner which took just over an hour (65 min) and bogged the engine more often. Bogging was due both to heavier, taller grass and also due to uneven ground. As noted though I did bog the motor occasionally and had to adjust throttle, especially on the second job, I heard no belt squealing at any time.

Drum roll: Here are the measurements. All temps Fahrenheit and measured within a minute or so of removing the belt cover. For each site, the first temp is with standard spring, second is with the solid bar.

Belt cover: 159, 166
Top pully center: 198, 217
Top pully peripheral: 219, 230
Bottom pully center: 215, 230
Belt at top: 210, 224
Bearing cover on opposite side of mower: 104, 100

There is a consistent pattern that the measured temps were higher after the second mowing with the solid rod. As noted earlier, this was a somewhat longer and tougher mowing job as it turned out. Still, it seems pretty clear that 1) the solid rod did not markedly lower the belt or pully temps even though belts were tensioned equally to 3/8 inch Iron Horse thumb blanch deflection units with both trials. 2) The other notable point is that this puppy runs hot when doing serious mowing.

There was no smell of burning rubber and the belts on my mower look fine on close inspection. I have about 30-35 hours or so on the mower now with most of that being bush hogging and the sort of field grass mowing I did today. No lawn cutting or easy stuff. No cracking on the belts. Belts are smooth. The belts fit flush with the tops of the pully belt guides.

I grabbed some photos just to show belt tension and idler wheel setting but will post those later. Nothing dramatic.

Any chance one of you with a different brand flail mower could get similar measurements with an infrared thermometer to compare? Mine only cost $45 and you'd be surprised at the number of things you can take temps on to impress your friends and neighbors.