Cub Cadet garden tractor eating PTO belts


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Old 05-19-24, 05:35 PM
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Cub Cadet garden tractor eating PTO belts

My Cub Cadet has suddenly decided it wants to break PTO belts.

It's an 18-yo 2544 that I've had going on six mowing seasons and it never broke a PTO belt until last week. I installed a new belt and the second one broke in about 90 minutes of operation.

I never smelled any burning rubber or heard or felt anything unusual until the belts snapped. They both broke almost straight across, with a little tail of cord in the center hanging out. Both of them were really warm, like almost hot enough to burn you, but I didn't see any signs of abrasion.

I checked the mower front end and deck pulleys after the first break and didn't feel anything concerning. After the second belt broke, I removed the deck and re-checked them and re-greased them, even though I'd only done it this past march.

And both of the the belts (which were OEM) were so tight they were hard to get on. I couldn't manage to get them to mount by putting them on the pulley on the mower deck last so I ended up at the other end, mounting them on the PTO pulley last. I used a super-long screw driver to lever the mower deck idler arm all the way to its limit to create as much slack as possible but with only one hand free I couldn't get the belt to follow the pulley around. A couple of the references I found on the 'Web said to check and adjust belt tension but there's nothing in the manual about it, so I'm not sure it's adjustable. And never having had to change one before I couldn't say if ir's normal for them to be so tight.

The only 'fix' I found that I thought might be applicable to my circumstances was to check the levelness of the mower deck. That obviously affects the line of the PTO belts but I wouldn't think it could be so far off as to cause a belt to overheat. But check I did and found my deck was most of an inch off level (I'm surprised I didn't notice the unevenness of the cut).

With the third belt in two weeks mounted, pulleys greased and the deck leveled, I went back to the yard but I only mowed a couple of turns before shutting it off and checking the belt temperature. It was pretty warm, not as hot as the ones that broke, but hotter than I would think is 'normal.' And I went back to mowing but only enough to finish the section I was on, then I checked the belt again. And I'm pretty sure it had got hotter still, but it still wasn't as hot as the ones that broke. That was when I decided to call it a day.

So before I break down and spend money to have it put right, anybody have any suggestions?
 
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Old 05-20-24, 01:22 AM
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A belt can be "read" to determine what caused it to fail. Your description of the break sounds like a tension break, usually happens when the blades hit something suddenly and come to a stop or when someone engages the PTO and the belt is sub-par and lets go instead of getting the blades up to speed. The tensioner pulley shouldn't be at it's fullest extended travel when the belt is installed. If it is, that indicates a problem. Either the belt is routed incorrectly, over a guide, a pulley is the wrong size, the belt is wrong, or something has bent and moved the deck away from the PTO clutch. Sometimes a hit to the front of the deck causes the front deck hanger attachment point at the front of the mower frame to move back, which makes the deck move away from the engine and in turn increases the belt tension.
 
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Old 05-20-24, 04:18 AM
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Maybe a bearing going somewhere in the drive train?
 
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Old 05-28-24, 07:28 PM
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I haven't been able to get it to a shop but today I started it up and ran it a bit, then checked the temperature of the PTO belt with an IR thermometer.

I put it on hardstand with the mower deck at it highest setting, engine running at full throttle and turned on the PTO for 60 seconds. Temperature at the time was mid-80s F. After the IR thermometer registered 127.

That sounded unreasonably high to me for a "no-load" condition so I pulled the deck off (again) and greased every zerk fitting I could find, and gave the deck a GI cleaning. Tested every pulley and they all seemed to turn freely. Repeated the 60 seconds at full power and the PTO engaged and the second time the belt checked 115. Which still sounds high to but less threatening than 127F.

The PTO layout is pretty simple and straight forward and I can't figure what it is I'm overlooking, but there must be something, else I wouldn't have blown the second belt, and I don't think I'd still be having a belt running at 127F.
 
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Old 05-29-24, 06:28 AM
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I feel kinda silly going behind Cheese but what crossed my mind was;

If while removing the deck or changing belt, you have removed or "unhooked" that large heavy duty spring, you may have reinstalled the spring in the wrong hole (wrong location) on the deck, thus causing more tension on the pully system, making the belt too tight. Make sure you reinstalled the spring in the correct holes etc.

Just a thought.
 
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Old 05-29-24, 01:42 PM
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If you're referring to the PTO's idler arm assembly, there is no adjust ability or multiple holes.



The whole contraption is simple and straightforward (i.e., idiot-proof) in design and operation. That's why it vexes me that I can't work this out.

When I engage the idler arm lever, the PTO belt is taut enough that when I pluck it it "twangs." So it's pretty seriously tight but never having had reason to twang it before, I can't say it's tighter now than before it started popping belts. There's a bit of slop but not much.

The fore-and-aft location of the deck is fixed by the implement lift links and rear deck brackets (below). These don't show any signs (that I can see) of having been damaged, and are so sturdily-built that if they had been knocked out of kilter by bashing the deck into something, I would expect it would also impact the raising and lowering of the deck. Which as best as I can figure is working normally.



And below is a photo of the break in one end of one of the belts (which should have been in my OP). The break was very nearly perpendicular to the belt but it's tilted toward the camera to show the inner damage.

 

Last edited by Fred_C_Dobbs; 05-29-24 at 03:03 PM. Reason: bat spellink
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Old 05-29-24, 08:38 PM
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Looks like an over-tension break. Is the front of your deck lower than the rear? Let it down close as you can to a level surface (garage floor) without the gauge wheels touching the floor and get back from it and kneel down with your head near the ground and see if the front is lower than the rear. If so, bring the front up, this will tilt the deck to line the pulleys up with the drive pulley better and reduce the tension on the belt. The front should be just a touch higher than the rear.
 
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Old 05-30-24, 09:46 AM
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Since most people want a flat looking mowed lawn versus a sawtooth, I would think the mower blades being parallel to ground trumps mower deck being parallel to ground (unless both being same but not likely) with the deck drive pulley orientation being what is left. Not a problem on my mower as the PTO pulley is vertical to horizontal deck pulley with vertical idler pulleys providing belt direction change. In this arrangement, mower deck drive belt pulleys relative orientation provides latitude. Yours may be different.
 
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Old 05-30-24, 07:57 PM
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I give up. As soon as I can figure out who has my trailer, I'm taking the mower to a pro. Yesterday I did one turn around the yard with the mower deck at the next-to-highest setting (on account of my grass is deep). After that maybe 2 minutes of mowing I could faintly smell burning rubber and the belt temp was 140F. It was cutting fine, despite the deep grass, but the belt was hotter'n blazes.

Cheese, thank you for all your advice. I went to the Co-Op's repair shop today and the free advice guy mentioned the deck level, which I set years ago but hadn't thought about until today. He said make it 1/8th inch higher in front or back but he said he thought they cut better if higher in the front. Last I set it I set it higher in the front, but it's beyond my mechanical talent to get the 1/8th inch right. so I'll settle for any amount that lets me be sure it's higher in the front. I'll check that tomorrow before I haul it off.

The Co-Op free advice guy also said it could be that one of the bearings in the mower deck is worn out but the play is undetectable without the tension that the mower belt applies. Not sure how I would check that, being that the belt tension pretty much firms up everything. My usual mower guy has been gone on a hunting trip but he's due back on Saturday, and none too soon because it's the height of mowing season and all the other mower shops in town are a month behind.
 
 

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