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Discussion Starter #1
I have an old 197x vintage MTD 143-990 tractor with a bad lower PTO assembly. The PTO pulley and PTO shaft mutually self destructed, probably because of the wear of the two supporting PTO bearings.

I am interested in finding somebody with just the pulley and the shaft or the whole PTO bearing assembly. I would prefer used parts since I do not want to put a lot of money into my 30 some year old tractor.

The MTD part number for the double pulley is 756-0177 although it has 719-0175 stamped on it. And the PTO shaft MTD part number is 738-0156.

I found these parts at a site online that even listed them 'in-stock' and so I ordered them, but two days after I ordered them I got an email that said that these parts are no longer available. If anyone has an idea where to find these parts please let me know.

I did find multiple sources for the bearings, so they are hopefully not a problem.

Thanks,
Rich
 

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The MTD part number for the double pulley is 756-0177 although it has 719-0175 stamped on it. And the PTO shaft MTD part number is 738-0156
Does yours take the smaller (1/2") or larger (5/8") belts? The early, small belt model had an idler pulley for the engagement that stretched the belt outward, and later, larger belt model had an idler pulley that rode on the outside of the belt.
 

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Discussion Starter #4 (Edited)
My tractor does use a pair of 34" x 1/2" belts (PN 754-0165). However, it also has an idler pulley that pushes from the outside(back) of the belts to engage the PTO.
 

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I have a complete PTO set up with the smaller belts if interested . . .
 

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I can snap some pic's of it tonight after work for ya. The belts will be included.
 

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I don't have the shaft and pulley to sell but I did just rebuild mine. It takes a pair of bearing number 6204-2RSNR. They are normal 6204's but with an o-ring groove. Mine were ready to grenade any minute. Some balls were already missing and the seals were long gone.
Some 990's are different and have needle bearings and thrust bearings. Mine is the newer style (1973?) that takes 1/2" by 34" belts with the tensioner contacting the backside of the belts. Good luck finding the parts you need. Rick
 

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Discussion Starter #10
That looks remarkably the same as my PTO bearing assembly. I just want to make sure that the pulley seems to be firmly attached to the shaft without any play? That is where my PTO assy has failed. My pulley now has a 1/8" oval shaped gap between itself and the shaft.

So, the next question is what is the easiest way for me to buy this?
 

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That looks remarkably the same as my PTO bearing assembly. I just want to make sure that the pulley seems to be firmly attached to the shaft without any play? That is where my PTO assy has failed. My pulley now has a 1/8" oval shaped gap between itself and the shaft.

So, the next question is what is the easiest way for me to buy this?
Have you tried to replace the bearings? The one I have here, I would recommend replacing the bearings in it. They are really easy to do. I did mine, the one on my tractor. If you want me to rebuild it for you I could do that too. That process would include Cleaning, replace bearings, and paint. Let me know.
 

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Discussion Starter #12 (Edited)
The problem is that it appears that the pulley came 'slightly' loose from the shaft. After one hour, that slightly loose fit turned the nice round pulley hole, into an 1/8" to 1/4" oversize egg shaped hole in the pulley. And in the process, the shaft is also seriously worn into a oval shape where the 'key' and the pulley attached. This all happened rather quickly while mowing the lawn only 2 times.

I have disassembled the whole PTO assembly and the bearings do not appear to be that bad, but I would replace them anyway, since I really think that they must have partially seized. The PTO shaft is a little worn where it contacts the bearings, which make me think that the shaft must have been slipping inside of the bearings at some point.

I have attached a cell-phone picture of the damaged pulley and shaft, but it is hard to see how badly damaged the two pieces are from this picture.

I actually ordered 2 bearings for my old unit before I found that I could not easily find the pulley or shaft.
 

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Due to the poor design, there is nothing to lock the whole assembly together properly. Just a lock washer binding the outlying bearing. After building up both bearing surfaces today, the pulley land will also be built up and the bore of the pulley bored out to match and the race bearing surfaces turned down for new bearings. A tube between the bearings should help lock them together and keep them from spinning in the future.

Most likely any used one is well used and liable to have this problem that needs addressing. Plus rebuilding the keyway too.

I have to do this on the front PTO also, at least the pulley. Is it possible to get the adapter shaft for such an old 16hp Briggs? Save me some work, not sure where to look for particular engine parts. Briggs 326421 engine,

Thanks
 

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I just made this drawing for the PTO Shaft if you can have someone make it for you. I hope this helps. If there are any questions let me know.


Very nice drawing.

Update: I sold him the extra PTO I had.
 

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Does anyone have a cheaper source on the bearings for the 990 rear PTO?

MTD part# 741-0161

MTD wants $31 plus shipping each. Both of them here look and feel really well, and their bores are reading right at 20mm.

Thanks for the diagram, forgot to do that before brazing. In a rush, this is taking too long.
 

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I went to the local bearing store. I think that's what I paid for both of them.
 
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