EX120-3 Slew Gear Bearing Grease Dilution

[Maine HD6B Dude]

My Ex120-3 Slew Gear Bearing grease is being diluted with hydraulic oil. If this is from the Swing Motor reduction gear, why isn't the level going down? The oil in the reduction gear appears to be hydraulic and not gear oil. If the Swing motor seal is leaking, wouldn't the reduction gear box be overflowing. I guess the swivel is ruled out because it's leakage would be internal. I have recently purchased this machine.
Mike

 

[cps]

I guess the swivel is ruled out because it's leakage would be internal. I have recently purchased this machine.
Mike

Not always the case, i have seen a few swivel joints leak into the slew bearing! The big o-ring in the swivel joint goes hard a brittle! If it is hydraulic oil for certain then id say its your swivel for sure, you can pull the rubber boot to one side around the swivel and may see the oil leaking out!

hope this helps, Aiden

 

[Maine HD6B Dude]

Hello Aiden,
That is what I want to hear. Someone said awhile back that it could be the swivel. I did check under the boot a couple days ago and it was wet with hydraulic oil. With the grease dripping out of the slew gear bearing, does this mean there is a high level of hydraulic oil getting into the bearing or oil dripping directly into the bearing? What I am trying to say is that the area under the slew bearing was clean and dry but, after one hour of work, there is enough oil and grease to fill a coffee cup. How can that much oil leakage get into the bearing?
Mike

 

[Mjrdude1]

Most swing bearing cavaties have an access hole with a cover on the top of the carbody for checking grease level in the gear area. the swing drive gear needs to have grease for lube between the drive gear and the swing bearing gear. If you have oil leaking around the outside of the bearing it would indicate the cavity is full of oil and it's seeping into the bearing at the joint between the bearing halves. It will eventually wash all the grease out of the bearing and shorten it's life.
Usually it's caused the the swing drive gearbox lower seal failure, in your case sounds like the swivel. The swivel can be resealed, just make sure to mark connections of the hoses before removing it. Also if you find the cavity is dilluted, make sure to clean it out and put the correct amount of grease in it, too little and the drive gears are not lubed, too much and the drive gear seal is ruined by cold weather operation.

 

[cps]

I have seen a swivel leak enough oil to empty the tank in a shift! That was an extreme case though! Like Mrdude1 says, you can access the grease pan under the bearing through an access plate between the main lift rams on the main frame! you should drain this out and regrease the bearing after you have resealed the swivel!

Aiden

 

[RobVG]

I've done 2 ex 120-5 swivels. Same type of leak. Not a bad job. Worst part is cleaning things up before you start. Seals were not cheap.

Edit: Um, that was 8 years ago. The swivels needed repacking but I don't really remember where the oil was coming out.

 

[Maine HD6B Dude]

Good Day,
Thanks alot for the info. I will tackle the Swivel reseal job very soon.
Mike

 

[Maine HD6B Dude]

Hello,
Finally got to rebuilding the swivel and found that the sealing o-ring was worn down considerably. I changed the bushing and all the seals. I will not go through OEM next time. Unit tested out A-OK.
Thanks for all the help.
Mike

 

[rorydelmue]

Hello,
Finally got to rebuilding the swivel and found that the sealing o-ring was worn down considerably. I changed the bushing and all the seals. I will not go through OEM next time. Unit tested out A-OK.
Thanks for all the help.
Mike

Just reading your past post here. I am having the same issue with a ex120-2 I just bought at auction. I don’t know any history on the machine. It leaks a lot of hydraulic fluid into the slew gear cavity. The swing gear box fluid is constant so I am ruling out the swing motor. I pulled the boot back on the swivel joint and see a little bit of wet, but it doesn’t look the the large amount coming from the table. Am I missing something here? All the covers are off and still can’t find the large source of fluid leak. Did the swivel joint fix your leak? And if so did it look like it was a big leak from the swivel joint? I am thinking it must leak under load and I just don’t see it leaking.