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Discussion Starter #1 (Edited)
Well I was getting the Hydro rebuilt, because the entire unit was getting way too hot. So I show up at Ray's mower shop of Boyertown Pa for a drive shaft u joint, we get to talking about the hydro, when he tells me to check the rear for a destroyed Bull gear that could be the reason for the failing hydro. The last thing I was expecting to do was rebuild the rear too, here is where I fell deeper down the rabbit hole.




I get to the bull gear in the rear, and I can't believe the condition of it.





The entire casing is full shavings that made there way right through the hydro, so I have to beak the casing's apart to wash all this out. One thing for sure had I not torn this down and fixed it, I surly would have damaged the new hydro. Below is a pic of the original bull gear next to the rebuilt one I scored from Ray's.

 

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If those are recent pics, then someone else had the same problem last year and took almost identical pics showing identical damage.

If I recall, there were several good suggestions for repairing the damage.
 

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Wow! So how does somebody rebuild something like that?
Does the damaged portion get pressed out from the surrounding gear and then a new readily available one get pressed in?
 

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Discussion Starter #4
He explained to me how the machine shop did it, it was some real deep machine shop knowledge that was way beyond me. He did say that even mine was rebuild-able, they would take the bull gear which is way over built "even with that damage", turn it 180 degrees then machine the grove for the pin into the bull gear. He did say that the pin was an off size and they had to have it hardened.

Then they updated the design by adding hardened washers behind the Pinion bevel gears to keep them from grinding on the bull gear from the start. A shortcoming in the original design they believed, as from the factory without the washers, the grinding on the bull gear would start immediately.

I can't believe it still worked, how you can test for this is to jack up the rear wheels and spin them both forward then back. There should be almost no play in a good rear, mine had 5+ inches of play forward stop to back stop.

I took some of the pics about a week ago, & some yesterday, trying to be more consistent in taking pics for a smooth flowing story.
 

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Your pictures are great.
So it's ray that's having a local shop rebuild them? Do you have to return your original to Ray?
 

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Discussion Starter #6
He used to do them in house, when the demand was there, now he has a shop in the area do them, (maybe a little bit of both). He would need your core to do the rebuild.
He told me he used to get $450 for them when they were in demand, but since I was the fist guy to ask for one in over 5 years he gave me that one for $150, that has been sitting around. He may have more, I just don't know.
 

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Here's how mine was fixed. Although on an HT-20, it's the same thing.

http://www.flickr.com/photos/[email protected]/1215029205/in/set-72157624632644721/

http://www.flickr.com/photos/[email protected]/sets/72157601619301405/

http://www.flickr.com/photos/[email protected]/sets/72157601612350438/

One set was done about fifteen years ago, the other about 10/12 years ago. The older one is on the HT-20 with a FEL and Carlyle ags. The tires (26x12x12) are fluid filled, cast weights, box blade with four cement filled cinder blocks on top. LOTS of traction. The bucket is 48" wide and I can drive it three inches under sod and pick up about 24" of it. With all that this Bolens has done since that rebuild, the axle play is still less than 1/2". Getting that bull reworked will last at least another thirty years!
 

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Discussion Starter #8
Ok, time to wrap this up; the amount of steel shavings in both the main casing and in both arms to be washed out was just unbelievable.















I strongly believe now that the first thing one should look at when reviewing a prospective purchase is the rear transaxle first, and check the play forward to back. As the rear fluid is combined with the hydrostat, and if the rear goes, it will take the hydrostat with it and be very costly. Then make checking the motor #3 on the list, these units are getting really up in years, and I bet this is getting real common.
 

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I strongly believe now that the first thing one should look at when reviewing a prospective purchase is the rear transaxle first, and check the play forward to back. As the rear fluid is combined with the hydrostat, and if the rear goes, it will take the hydrostat with it and be very costly. Then make checking the motor #3 on the list, these units are getting really up in years, and I bet this is getting real common.
That's what filters are for.
 

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On most hydraulic systems unless they are a very fancy set up the fluid is filtered after it goes thru the system on the return side,most have a screen to filter the intake side but very small particles that can destroy hydraulics can pass thru them.trz430 I was wondering what the final bill was?
 

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On most hydraulic systems unless they are a very fancy set up the fluid is filtered after it goes thru the system on the return side,most have a screen to filter the intake side but very small particles that can destroy hydraulics can pass thru them.trz430 I was wondering what the final bill was?
Hydros have the filter on the supply side specifically for this type of situation. Most normal hydraulic systems do not have gears and bearings, with their associated fine particle wear products, residing in the reservoir and can get away with only a screen on the pump supply line.
 

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Discussion Starter #12
Yea Tudor, normally I would agree with you that the filter should do the job, but below is the pan filled with metal shavings after the case was cleaned. So I don't know how much credence to put in the filter. There is no screen for the inlet as with this design it would be impossible to service with reasonable ease.



As for the price, let's divide this into two threads, let's finish with the transaxle then I will start a new thread for the hydro.

The only cost on the transaxle was the bull gear at $150, and I did all the work, the hydro,,, a whole different animal.
 

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Yea Tudor, normally I would agree with you that the filter should do the job, but below is the pan filled with metal shavings after the case was cleaned. So I don't know how much credence to put in the filter. There is no screen for the inlet as with this design it would be impossible to service with reasonable ease.
Just goes to show you how much the filter collected if all of that was left in the sump. When I drained the oil from my final drive when it had severe mechanical damage, it looked like metal flake paint as it was pouring out, and as it lay in the collecting pan. All those suspended particles of metal would have been trapped by the filter, along with all the particles that were already plugging the filter so bad that the drive would only work for 20 minutes at a time.

What is laying in the bottom of your pan are the bits that were too heavy to go into suspension and never made it to the filter, along with all the fine bits that settled out while the tractor was down between jobs. That damage was a long time being created in a machine that probably didn't get used for more than 100 hours a year.

It's one thing to have confidence in the filter. It's another to insist on verification of that confidence. Check the valve plates in the hydro for scratches, as well as the pistons, bores, slippers, and swash plate, and don't forget the gears in the charge pump.

Lots of clean, lint free rags.
 

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Brilliant idea to re-mill the bull gear at 90 degrees. Yes, I would like to see what was done for the hydrostatic.
 

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TRX,

Awesome write-up on the transaxle rebuild. I'm in the process of rebuilding mine because the LH axle shaft is actually broken in two at the splined end near the bull gear.

This transaxle is in an HT20 with a loader that I bought a couple of years ago when another MTF member posted that the machine just quit moving.

Your post could not have been timed more perfectly. Thank you for taking the time to share your experience and post your pictures.

I'll be watching to see your progress.
 
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