Sears tractor keeps destroying pulleys

[John]

Hello

My Sears 1000 XLT tractor is driving absloulutely nuts . The pulley that drives the left side blade keeps stripping. The pulley is attached to it's shaft with a star connection. If I hit a root or stick or for whatever season the blade is stopped the belt will keep the pulley spinning and the connection is destroyed. The star opening on the pulley gets every so slightly stripped and enlarged and begins to saw away at the spindle destroying both within seconds. This happens only on the left blade, never on the right. To replace the pulley and spindle costs me about $60 each time. so far in the two years that I have owned time machine this happened 4 times! Can anyone tell me what going wrong ?

John

[dpb]

Sounds like you're hitting stuff that shouldn't be. _Something_ is going to give if you hit something solid enough to stop the blade while the drive is engaged. Don't know what you expect to happen???

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[salty]

You need to WALK the area and remove all these obstacles that do not belong there. Your blade should not be hitting anything but grass.

[DerbyDad03]

I'm not going to disagree with sa or dpb, but I'll admit that it does sound strange that if an obstacle is what is causing the problem, you somehow managed to hit it (or them) with the left blade 4 times and never with the right.

Is the left blade closer to the ground? Do you always (typically?) follow the exact same route such that the left blade meets the obstacle but the right never does?

Obviously clearing all obstacles is the first thing you need to deal with, but I would also try to determine what is different about the left side blade vs. the right - either its position on the tractor or the route it travels when you mow.

[dpb]

...

I'm not taking offense as you don't intend to be critical I understand, but I'll add a little note... :)

He says the blade is stopped by an obstruction while in gear.

If there is something other than an external cause, that would be a fault that could be addressed mechanically otherwise nothing but changing the operation would seem to address the problem.

I do suppose the chance of the leveling could be a contributing issue, but if it is so bad as to cause the left side to be digging in to the point it stops a blade tip and the right not, one would think the unevenness of the cut would be obvious enough to be noted.

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[salty]

He could always go out and deliberately hit a tree stump with the right side as an experiment to see if it also breaks! LOL

[Chris Lewis]

According to John :

Despite what others say, it should be able to stop momentarily without destroying anything. I hit lots of things (rather rough ground in places), and I've never had any damage (except for the blade getting dinged of course).

Can you slacken off the belt a bit so it'll slip? Maybe it's too tight.

[DerbyDad03]

I think we are on the same page here. That's why I mentioned both the position of the blade and the route taken.

Let's put a root out in the middle of his yard. Now let's assume his left ball...err...blade hangs lower than his right. If he travels a route than continually takes his left one over the roots, he going to smack it everytime he goes by (ouch!). However, if he varies his route a little to one side, the right one might clear it.

This could happen due to uneveness of turf, a physically lower left ... blade, or even a left blade that is bent differently than the right.

[dadiOH]

Can't say for sure but it sorta sounds like there is vertical wobble at the star (shouldn't be). One thing sure, hitting a stick should

*NOT* cause what is happening...I regularly hit oak roots and fallen branches - branches up to 2" in diameter - with no damage other than dulling the blade which is always dull anyway. I don't mow, I thresh :)

I've never even had debris stop the mower unless it is physically big enough and oriented so it gets kicked up and wedged in the blade housing. In that case, the blade drive belt slips. And smokes if I don't shut it off. You sure your belt isn't too tight and that you are using the correct length (BTW, belts are a lot cheaper at auto stores). No wobble in the pulleys? All the bearings good?

[DerbyDad03]

Good point. Shouldn't there be a sheer pin or key that would give before a pully would strip out?

[dpb]

But it's that far off and he hasn't figured that out???? Seems farfetched to me. Not impossible, but surely unlikely I would think unless the guy is also blind as well as imbalanced... :)

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[dpb]

That would be "shear", curtains are "sheer"... :)

If there were one, certainly one would expect that to occur. Many cheapies don't. I wouldn't expect to hit anything so hard so frequent as to stop a blade entirely dead w/o causing damage.

Not sure what OP is calling a "star" drive -- could be that it's failing there because it was designed as the weak point. The JD's I have use a keyed shaft and the key serves the function of the shear pin.

Whatever it is, I still say the solution is most likely the answer to the old story about the doctor's solution to the complaint "It hurts when..." :)

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[Oren]

(multi-posted)

Agree about the belt. Over tightened belts will cause faster wear on bearings, bushings, etc. I've seen this happen on alternators and older car generators.

[DerbyDad03]

re: unless the guy is also blind as well as imbalanced

Hey, he's replaced it 4 times in 2 years and he's just asking about it now? Who knows? ;-)

[Eric]

I wonder if the deck is designed in such a way that if the right blade hits a loose object it gets deflected or ejected thru the chute, but when the left one hits something it gets wedged and stops the blade?

Eric Law

[John]

Original poster here:

Thanks for all the replys. I have done quite a bit of root removal and I ry to be careful.It's never going to be completely pristine yard though . But it seems to me the trackor should be able to take a bit of punishment. My old Wheel Horse which was a third the price would hit obsructions too but in that case the belt would slip an I would see and smell it burn. I'd stop without much damage being done . I think I must be missing something. The belt is not all tight, the pulley was bolted down very well and still I'm broken down for god knows how long. I question is , has anyone had this happen to them as well ? Is there a design problem?

[DerbyDad03]

re: That would be "shear", curtains are "sheer"...

I've alweys heted thet thay put the "a" key so close to the "e" kay. I gat tham mixed up all tha time.

[tnom]

Is this a spline shaft?

Steel is not just steel. Properly heat treating the correct type of steel makes a huge difference in the longevity of a splined connection.

Are your replacement parts aftermarket parts? Did Sears change their supplier of parts? Can you swap left from right to troubleshoot this possibility.

[dpb]

I don't really think so, no.

What are you actually hitting?

My suggestion w/o seeing what your situation is to raise the blade higher so it doesn't hit obstructions.

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[Oren]

Isn't a pulley pressed onto these spline (star) shafts?