853 Sundstrand Hydrostatic Pump

[HMILLER]

This question concerns the right side of the hydrostatic pump as determined by sitting in the operators seat facing forward. The right control stick is cable attached to the neutral adjustment bracket, which consists of a control arm (the horizontal bracket) and the Spool ( the vertical rod that goes into the pump casing). When operating the right control stick forward or reverse, the horizontal bracket actually moves up and down about 1/8" along with its moving on its axis making it appear to be loose on the spool or the spool loose in its casing. The right control arm and spool actually appear to have a wobble in it. The same assembly on the left side that is attached to the left control stick only moves on its axis, no wobble. I hope I've described this clearly enough to make sense as I couldn't figure out how to attach a PNG photo file to this question. Any ideas as to what causes this wobble and what any future failures could be in store here?

 

[HMILLER]

Just added a photo in the gallery section showing control arm and spool I'm referencing this question to. File is called 853 Sundstrand Hydrostatic Pump.

 

[Tazza]

Just added a photo in the gallery section showing control arm and spool I'm referencing this question to. File is called 853 Sundstrand Hydrostatic Pump.

Are there any obvious spots of wear? They need a little play to be reliabily move, but what you have may be a little too much.
I have never worked on am 853, so i can't tell you for sure what it should be like.

 

[HMILLER]

Are there any obvious spots of wear? They need a little play to be reliabily move, but what you have may be a little too much.
I have never worked on am 853, so i can't tell you for sure what it should be like.

Can't see any obvious wear, but this is definitely too much wobble. Checked the service manual and it appears that there are several o-rings, etc. on the spool. Don't know if that would contribute to wobble.

 

[Tazza]

Can't see any obvious wear, but this is definitely too much wobble. Checked the service manual and it appears that there are several o-rings, etc. on the spool. Don't know if that would contribute to wobble.

There are orings and a sleeve. You need to be really careful with these parts, they are easily damaged from memory.
If there was excessive wobble, i would have thought there would be an oil leak....

 

[HMILLER]

There are orings and a sleeve. You need to be really careful with these parts, they are easily damaged from memory.
If there was excessive wobble, i would have thought there would be an oil leak....

Quite possibly a leak there running down back of pump. Am in process of building the engine removal bracket to pull engine/pump assy. Will know more after the removal. I think the orings are a good bet.