Grease gun overlubrication of roller bearings

[martwizz]

Hey guys

 

Since I first started until yesterday, I have always used a greasegun to lubricate roller bearings 'daily' as instructed by colleagues and stickers on machinery. I simply pump until a bit comes through the seal, assume its full, clear the excess and carry on with my day.

 

However I have been reading about machinery lubrication, and it turns out that overgreasing is a huge reason for the deterioration and failure of roller bearings.

 

Overgreasing means that the bearings glide instead of rolling, which compacts the grease and squeezes out the base oil. The soapy residual grease that remains doesnt have lubricating qualities, so the joints wear and heat up, which causes the wax to harden. From here a variety of issues arise, as you can imagine.

 

So as a first point of call, to everybody who didn't know about this, now you do, and its actually pretty important. One of my employers had a flywheel bearing change on his timberwolf which was in a horrid state, and in hindsight it could well have been a result of overgreasing.

 

Now a question for the members who knew and are mechanically minded:

 

Recently, when I've gone to grease the main flywheel bearings of my HB20, I've noticed that grease no longer seeps from the entire seal, and rather just from one point near the nipple. As mentioned before, I greased it before every day of use with a greasegun. It doesn't seem to take nearly as much in as it used to either. I have concerns that my negligence of correct lubrication may have started to lead to the aforementioned issues (build up of hardened waxy grease). Its important to note that there doesn't seem to be any excessive vibration, heat or stiffness (yet).

 

Is there a simple way that I could clear out the bearings and re-fill them from scratch? WD40, or white spirit, or petrol? Its not something I want to take to pieces myself at this point.

 

Cheers boys!

[Johny Walker]

are the bearings on a hb20 purge bearings or sealed , purge bearings are the 1, you pump till you see clean grease , sealed a couple of pumps so not to blow the seal,

[PeteB]

Hi Martin, you are correct in that you can over grease bearings and do more harm than good. The gallery that carries the grease from the nipple to the bearing races can get blocked and then it is hard to get grease to where it is needed and pumping in too much grease can pop the seals out too.

 

Sometimes it is advisable to rotate the part will introducing the grease, this could get it in fairly equally. Ine something a grinder, there is the school of thought that purge/cleaning is best but on a chipper, I would've said 2/3 pumps once a week would be ideal.

[treequip]

However, in slow moving applications like roller boxes the grease seldom gets anywhere near what in most applications would be considered normal operating conditions, particularly temperatures.

 

In these slow moving, high contamination environments its often advisable to grease on the heavy side to purge contaminants.

[NFG]

Agreed,

 

Over-greasing is a cause of bearing failure, ran a reactor plant with dozens of pumps years ago & bearing greasing was carefully controlled.

 

Dont know enough about HB20 but I would consult manufacturers

 

 

N

[Jonny69]

Hey guys

 

 

Recently, when I've gone to grease the main flywheel bearings of my HB20, I've noticed that grease no longer seeps from the entire seal, and rather just from one point near the nipple. As mentioned before, I greased it before every day of use with a greasegun. It doesn't seem to take nearly as much in as it used to either. I have concerns that my negligence of correct lubrication may have started to lead to the aforementioned issues (build up of hardened waxy grease). Its important to note that there doesn't seem to be any excessive vibration, heat or stiffness (yet).

 

Cheers boys!

 

I grease my HB20 several times per grinding day and always when its really warm. I keep pumping to pretty much replace most of, if not all the grease. Comes out smoothly all the way round and rarely look dirtier than it went in.

 

You do have to keep an eye on the right hand side grease nipple getting clogged as it tends to be in the dirt a lot and this make it hard to pump.

 

No idea if greasing warm is a good idea but you drain engine oil warm so I figured its pretty much the same.

[cornish wood burner]

Its the base oil that does the lubrication so if you are heavily loading the grease or running at extreme temperatures and speed the oil will be shed quicker from its carrier. Once this happens then as you say Mart the remaining soap does not have the correct lub properties.

Many years ago my collegues did have a damaging case of balls skidding in a gyro bearing but apparently that was down to the lub used being too slippery. That shows you need to use the correct grease for the bearing applied in the correct quantity at the correct interval, considering the loading and temperatures it will experience. I have always worked on little and often but the manufactures guidelines

should of course be followed especially in high stressed situations.

The other thing I have seen too many times is the grease gun put on the nipple without cleaning it first.

Any grit etc present will then of course be pumped into the bearing

[Ty Korrigan]

Martin,

The bearings have a wee channel and holes which seems to block easily.

Even when we purge grease 3 times a day it eventually blocks and the bearing recieves less and less grease.

You may dismantle the bearing from it's housing and clean it out or replace.

The bearings are quite inexpensive if bought from a bearing supplier. Global supply them with the cast housing which is not required and very expensive.

Regards

Ty

[openspaceman]

I

Many years ago my collegues did have a damaging case of balls skidding in a gyro bearing but apparently that was down to the lub used being too slippery. That shows you need to use the correct grease for the bearing applied in the correct quantity at the correct interval,

 

... but can one ever over grease a plain bearing? I know a build up of grease oozing round a shaft can be one of the ingredients of a grinding paste.

 

The other thing I have seen too many times is the grease gun put on the nipple without cleaning it first.

Any grit etc present will then of course be pumped into the bearing

 

which is one of the reasons for sealed for life bearings. Even just wiping over a grease nipple can push a bit of grit past the ball, but yes the nippe should be cleaned first.

 

I regularly greased my Cranab every day of use from 1984 and it was still going strong when I parked it up 7 years ago ( must go and see if it's still there ;-)) but I'm seeing premature failure on joints and bearings on the firm I do work for simply because users don't grease and fitters don't read the service instructions.

[simonm]

i like to grease the living **** out of my tackle! never had any problems or bearings go so far. Especially on me stump grinder, had it 3 years and its still on the original bearings.