MF 220 digger slew actuator seals.

jf850 said:

I have a 220 back actor on an MF 50 . It must be 15 years ago that it started leaking oil out of the top of the slew motor , where the outside "pot " turns .
I asked an MF expert , eg a man who had a similar machine for years .
He told me that what happens is ,
Dirt get down into that round groove , sits on top of the seal . It then wears the steel at that point , as well as wearing the seal to a certain degree.
The cure . There is a ring of Allen headed bolts holding the top ring on the pot . Open out all the studs , then , there are two threaded holes in the ring , but no threads for them to screw into in the bottom section . So , by screwing in these bolts , you are rising the top ring off .
The top ring is probably 2 1/2 to 3 inches thick. You will see the seal in a groove . Take it to an engineering place and they will machine a new groove in it , lower down , to take a new seal , that will.be sitting against a fresh undamaged bit of the inner shaft . Put a new seal in the old seal place as well . It will prevent dirt getting down again and damaging the new seal. From memory , the seal was a common seal , that the engineer had in stock himself .
Also , the slew pot should have a "Top hat " on it , which keeps the dirt out . I fitted a top hat when the new seal was put in and never had any trouble since .

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