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midnightpumpkin

Possible Powermax rear seal solution

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midnightpumpkin
Any of you who have had a powermax know about the problems with the rear seals leaking. My thoughts are that the seals fail, because the axle shaft is not adequately supported by the bearings. If the shaft does not run true in the seal, the seal is bound to fail. The axle shaft is supported on the inboard side by the differential which is supported by tapered roller bearings on each side of the differential. Outboard of the seal, the shaft supports the brake disks and then goes to a splined coupler to mate it to a stub shaft coming out of the drop box. The figures below show the inner and outer bearings I am talking about. In the figure below, item 28 is the drive shaft, items 9&10 is the tapered roller bearing, and item 8 is the seal, and item 11 is the support plate that holds the bearing and seal.


In the figure below, item 8 is the coupler (spline to spline), item 13 is the bearing, item 11 is the stub shaft, and item 15 is an outer bushing to support the stub shaft.


Now to get to my idea. I believe the drive shaft needs an additional bearing before the coupler. I am thinking of adding a bearing to the outer brake disk shown in the picture below.


It would require some sort of bearing retainer be welded or bolted to the disk to hold a bearing. Alternatly the bearing could be mounted in the axle extension adjacent to the outer brake disk. I would like to hear comments from any of you, on your thoughts on this idea, and any ideas to implement a bearing retainer. In summary, my thought is that the rear seal on an automatic transmission lasts for many years and many many miles, there is no reason the rear seals in the Powermax should not last just as long. Comments please. John U

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DMedal
Good thinking, John. It is obvious there's an engineering miscalculation on those seals, a weak link on a great tractor. How would you align that bearing? If the shaft and bearing aren't nearly perfectly centered in the seal it seems the stress on the seal would still be there, but I guess it wouldn't be moving back and forth. Maybe mock something up and post a picture of this? I wonder how many of us with a Powermax have no brakes? Don

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JP
I agree, point taken. I'm not sure the issue is that or just the tractors getting that old(?). 30 plus years is a long time for a seal to last. I have not heard back from customers that bought unit that the seals were replaced if there was a problem. Before 'buttoning up' the plate, I usually try to align the new seal as centered as possible. Seems to help.. The issue would be to see what would fit in the space available. Besides, Power Max's have brakes? :O

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