MM GTB Hydraulic Pump

dadleman · Nov 8, 2015

Am looking for a source to rebuild an Eaton pump that is part of the Uni-Matic hydraulic system on my 1953 MM GTB. OR, a source for parts for that same....

Alan K · Nov 9, 2015

What do you need for parts? Where are you located?

dadleman · Nov 9, 2015

Located by Lansing, MI. Not sure yet what parts I need. Haven't torn it apart yet, just know the pump is bad.

Alan K · Nov 9, 2015

Is there no pressure? Are you using an earlier MM cylinder with the lock out valves on it? If not it wont hold a load using another cylinder.

dadleman · Nov 10, 2015

I was dragging a disc thru a field when I started loosing power. Soon it was smoking from the tank/pump area. As soon as I unhooked the disc, it was fine. I think using the hydraulics to lift and lower the disc caused something in the pump to blow - maybe a seal or something. Won't know for sure until I take it apart. Was hoping to find a rebuilt pump or kit to do so myself.

This tractor has been rebuilt and bored out so it has plenty of power under any other circumstance - never had any issue until this one time using the disc.

Alan K · Nov 12, 2015

Does your control valve move freely and go back to neutral when the lever is released? If it stuck in one of the directions it could have affected the pump. The cam in the reservoir over time will wear and can slip out slightly and not release the valves back to neutral.

dadleman · Nov 13, 2015

(quoted from post at 22:06:04 11/12/15) Does your control valve move freely and go back to neutral when the lever is released? If it stuck in one of the directions it could have affected the pump. The cam in the reservoir over time will wear and can slip out slightly and not release the valves back to neutral.

No, it doesn't return on it's own...so maybe the cam is worn in the pump. With as much smoke and heat generated in it the last time I was using it - it must've done some damage.

Any thoughts on where I might find parts or a rebuilt unit?

Alan K · Nov 14, 2015

The valves work against pressure. When you move the lever and it "locks" into position, the valve is supposed to return to the neutral position (center / lever on reservoir straight up and down) when the hydraulic cylinder reaches the end of the stroke. If it doesn't Im betting the cam in the reservoir is an added problem as well. The Eaton pumps did have a problem with the keyway on the shaft wearing as well as the center gear on the shaft getting cracked by the keyway. They will still operate just fine when they are cracked though. They should be the same as a U, I will take a look in the parts book, if so I might have one here you can just install. It is a used pump. There aren't any rebuilts for those as far as I know. I think you would be farther ahead finding a different pump than repairing yours, since there are a lot of them out there more than the parts available.

MM GTB Hydraulic Pump

dadleman

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Alan K

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dadleman

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Alan K

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dadleman

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Alan K

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dadleman

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Alan K

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