Turntable bearing greasing

[wrwtexan]

A friend and fellow hoe owner had a question I thought I knew the answer to. He has been told that the grease zerks at the front and back of the bearing ring don't completely grease it and that it has to be hand packed on occasion. I thought they were the sole bearing greasing method and the hand packing under the plate was for the swing gear and ring. This isn't an argument between us as neither of us want the prospect of a $$$$ swing bearing replacement someday!

 

[td25c]

When greasing swing bearing will give it a few shots in one position then swing a few degrees giving it more grease and so on though the 360 circle .

After greasing will swing it several rounds in both directions .

Then back to work

 

[wrwtexan]

That's what I've been doing but he thinks those zerks don't fully lube the balls and race. He says he can feel the bearing balls when he hand packs inside under the cover on a 315 Cat??

 

[check]

As TD25 stated, you have to keep repositioning the turntable and greasing a little more as you go. When I worked on offshore pedestal cranes, I would tie the swing lever back with rope and while the engine idled, I would sit there and pump an entire grease cartridge in. I would do this once or twice a year. We called it "packing the ballring".
They told us to turn the crane about 7 revolutions clockwise quarterly so that the same balls don't do all the work.

 

[92U 3406]

Yep. Exactly what was stated above. Few shots in each zerk, spin it, repeat until you've done a full revolution. Should stop to put grease in it about 10-12 times in one revolution. No need to disassemble the bearing to grease it. The center tub is a different story. That requires old grease to be cleaned out and replaced with fresh grease to lubricate the swing gear.

 

[uffex]

Good day
Often an illustration explains hope it helps.
Kind regards
Uffex

 

[wrwtexan]

Excellent illustration! I had always thought the bearing was like an old style clutch release bearing/thrust bearing where a top race set on a ring of balls on top of a lower race but there wouldn't be a way to frictionless way to account for overloading and separation opposite the bucket side. As it is instead designed, I can now see it is even more imperative for good greasing habits. Thanks to all!

 

[check]

Excellent illustration! I had always thought the bearing was like an old style clutch release bearing/thrust bearing where a top race set on a ring of balls on top of a lower race but there wouldn't be a way to frictionless way to account for overloading and separation opposite the bucket side.

That's the same thing I was thinking. I suppose an excavator get pulled in so many directions they just design them in a manner that will hold the balls in place with least chance of escape. Any low RPM ball bearing will last almost forever if you keep it greased unless it's way underbuilt. I think failures are caused by lack of grease and getting submerged.

 

[John C.]

The bearing is basically greased like a sealed bearing and the biggest problem I've seen over the years is over greasing them. Some machines have three grease fittings and some have two. In either case all that is needed is put the boom between the track idlers and put a couple of pumps in each fitting. Now put the boom perpendicular to the track frame and put a couple of more shots in. Now spin the house three or four times in each direction. The other issue I've seen is greasing the bearing too often. I don't know how many times I've seen the seal blown out of the bottom of the bearing and pounds of grease stacked up on the carbody. Grease at most every forty hours and some manufactures recommended whenever you change engine oil.

The diagram is real good except it leaves out the plastic spacers that hold the balls apart. Slewing bearing can die from lack of grease but usually it is a two step process. Cycles is the first issue and overloading is the second. I've seen plenty of bearings fail in the 5,000 to 7,000 hour range due more to cheap materials or lousy design than not enough grease.

 

[xr4ticlone]

The bearing is basically greased like a sealed bearing and the biggest problem I've seen over the years is over greasing them. Some machines have three grease fittings and some have two. In either case all that is needed is put the boom between the track idlers and put a couple of pumps in each fitting. Now put the boom perpendicular to the track frame and put a couple of more shots in. Now spin the house three or four times in each direction. The other issue I've seen is greasing the bearing too often. I don't know how many times I've seen the seal blown out of the bottom of the bearing and pounds of grease stacked up on the carbody. Grease at most every forty hours and some manufactures recommended whenever you change engine oil.

The diagram is real good except it leaves out the plastic spacers that hold the balls apart. Slewing bearing can die from lack of grease but usually it is a two step process. Cycles is the first issue and overloading is the second. I've seen plenty of bearings fail in the 5,000 to 7,000 hour range due more to cheap materials or lousy design than not enough grease.

My man!

This is ONE of the places you do NOT want too much grease. As John points out you can blow the seals- you do NOT want to blow out the seals. That means taking the body off the x-frame...$$$$. I told customers 2-3 pumps in each side, turn it 90, 2-3 more pumps in each zert & don't touch it again. You'll know if you don't have enough grease. Also, your manual should give you hour intervals as well.

 

[check]

They must be making ballrings differently than they were 20 years ago. Back then the manufacturers of the cranes were telling us to grease them generously and often.

 

[John C.]

I seem to recall that the cranes I worked on were a lot different than what is found on an excavator. I seem to recall brass separators and a lot thicker races with many more bolts in the rings.

 

[uffex]

Good day folks
I noted with interest the comments made earlier and I must agree with John C about the over greasing, for those that are interested Roballo Engineering have many different types of bearings for applications other than excavators this animation may prove to be of interest.

Kind regards
Uffex