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klingra

I want to convert AC912 over to sundstrand hyd lift system

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klingra

I want to convert a AC912 tractor over to hydraulic lift system. I have a Simplicity 7117 parts tractor which has a hyd lift system on it. The parts tractor is basically only the back half. I would like to take the lift cylinder, hoses, valve, steel tubing off of 7117 and put those parts on the AC912. I want to use the current sundstrand pump unit that is already on the AC912 tractor. My Question is - Do I have to do anything to the sundstrand unit on the AC912, other than remove the plugs and install the hyd fittings to deliver the hyd fluid to the hyd valve? Do I have to change out any relief valves or remove - install any plugs? The AC912 tractor has a manual hand lift system on it. Any info, advice or expertise on this subject will help myself and other members. Thank You   

Edited by klingra

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PhanDad
5 hours ago, klingra said:

I may change out the whole Sundstrand unit or just the small parts specified. If anyone has any further advice, I'm all ears

Many ways to go on this one.  Most important is the shape of the donor rear end.  And does the donor include the BGB, cone clutch, and sideplates?  

If the donor is complete and in good shape from the BGB back, I'd swap out the rear ends.  It's a relatively easy swap and if it turns out it was a bad move, then it's easy to go to a more complicated transplant (and you know what the issues are with the donor components).  

If the BGB isn't part of the donor tractor, I'd consider swapping just the hydro motor if you know it's good or moving the "small parts" .  The reason I wouldn't swap just the complete tranny is I'm not a fan on messing with the cone clutch if it's working and it would have to come off to swap just the tranny - IMO there's not way to lift and rotate a complete tranny for the left axle hub to clear the side plate.

If your donor tractor has the swivel type elbows on the pump, I'd swap the "small parts".  On an early hydro lift install I did, the donor had fixed elbows and they couldn't be screwed in without taking the charge pump off.  I didn't want to do this, so I bought the newer swivel type fittings that came on later tractors.  They look like this:

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Unfortunately, like many Simplicity parts these days, they cost a fortune (part#1675789, $28.60 at Jack's).  I don't know if a similar part is available somewhere else.   And maybe removing the charge pump isn't that big of a deal so it would be easy to install the non-swivel fittings.  

Hopefully others will give their opinions.

 

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GregB

If your current hydro pump holds pressure when off, stay with that known rather than the unknown of the replacement pump.

As these hydros age they lose the ability to hold pressure, the result is drifting backwards on a slope.

So if you current hydro pump does not allow the tractor to drift backwards, I would say move all the small parts and be done with it.

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klingra

I have the old non-swivel hyd. fittings, so I will have remove the charge pump, if I go the parts route. My tractor does drift backwards on an incline. The donor tractor (7117) does not look as good as my tractor, which is an (AC 912H) with replacement 18 hp twin Magnum engine. I do have the 7117 rear out of the donor tractor. I may just put the whole donor Sundstrand hydro pump-hyd drive motor unit onto the AC 912H transmission.

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klingra

Well I'm half way to completion. BTW I am going with the small parts swap way. I have the Sundstrand small pump parts removed from donor sundstrand unit and installed into the AC912H sundstrand unit. I put a hose loop onto the AC912H sundstrand unit to make tractor usable until I get the misc. hyd lines, hyd valve and hoses put on. the pic will explain what I mean by a temporary hose loop. As you can see a sundstrand unit is mounted on the transmission with just 3 bolts.

 

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klingra

Well I got project completed about a week ago. The hardest part was welding in the tube bushing pivot point for the left hand hyd lift control handle. I also had to remove the hand lift rockshaft out of AC912H and replace it with the hyd rock shaft out of the Simplicity 7117 donor tractor. Who would believe that they had two different rockshafts for the same series tractors. One rockshaft for the hand or electric lift models, And one rockshaft for the hydraulic lift models. 

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JohnFornaro

Those swivel hydraulic fittings mentioned by Phan Dad above:  Part # 1675789, $28.60 at Jack's.  They leak, especially the supply fitting, which must resist a pressure of as much as 800 psi.  Worse, they're made in China, which IMO, explains the thinking behind the poor manufacturing standards.  As to the cost being a "fortune", that is a hard one to call on any other basis than personal opinion.  I've gotten tothe point where I absorb those costs since there's little other alternative, if one's time has any value.  Anyhow...

From my 20/20 hindsight department, I just typed in:

msc swivel elbow hydraulic fitting

to the googol.  The "proper price seems to be under $10 bucks.  It may be worth while for somebody to see if there's a less expensive swivel fitting.  I'm on a deadline at the moment, so I can't do it right now.

As to Klingra's remark:

"Who would believe that they had two different rockshafts for the same series tractors."

This aspect pisses me off to a certain extent.  forty or more years ago, Simplicity was just changing things for the sake of changing them.  In my fleet, there are any number of different designs for different parts that simply do not need to be different, but it made for higher profits for dealers.

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klingra

I want to show the differences in the rockshafts, There is one rockshaft for the hand lift or electric lift models, and one rockshaft for the hydraulic lift models. the difference is in the inside dimension of the clevis arms on the rockshaft where you connect the rod end of the hyd. cylinder to the rockshaft clevis. The rockshaft clevis arms are welded to close together. The cylinder rod is wider than the slot between clevis arms. Also the hand lift rockshaft has a longer shaft so that the manual lift handle can be mounted on the left side of the tractor. 

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Edited by klingra
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