Gear Box / Oil Seal Leakage

[sealguy]

Have a gear box used in the news paper insertion industry. The shaft diameter is 230 mm and is stationary. The OD rotates at 2000 RPM. Currently use a 230 mm x 260 mm x 16mm single lip spring loaded Nitrile oil seal. Out of 70 gear boxes we have had 3 leak after the machine was shut down. I think that centrifugal force is lifting the lip off of the shaft and the oil finds its way into some cavity. When the machine stops the oil drains.

Any one have any experience with this type of application?

 

[svanels]

Maybe the shaft or seal is damaged, maybe the gearbox is over filled. A 230 mm shaft gearbox must be quite big. When the equipment is shut down a lot of oil will flow to the low points in the box. Can be that there is a mininmal leakage during operation that goes undetected. Steven van Els
SAvanEls@cq-link.sr

 

[sprintcar]

Check your vents - it could be bleeding a bit of pressure out the seals. Keep the wheels on the ground
Bob
showshine@aol.com

 

[FINN_imported]

First I need some clarification. Are you rotating the gearbox aroung the shaft? This may be an application not mentioned to the gearbox manufacturer and may require a special seal due to pressure created in the box due to centrifugal force of the oil over the breather.
If the gearbox is stationary and you are rotating the shaft, you may wish to check into a VITON seal material in the same seal size. Heat causes degradation of the seal material. I suggest taking the temperature of the seal during operation, and comparing it to the seal manufacturer recommendations.

Good Luck,
FINN

 

[sealguy]

Gentlemen,

Thank you for your help. I did discover, after breaking down a test unit, radial scratches on two of the shafts. This must of occured during installation of the shafts. We have put in new shafts and are continuing the test.

Vents are clear and the seals were not damaged. This is a different type of gear box application where we rotate the Bore / OD around a fixed Shaft /ID. The OD is keyed to a drum. The seals were improperly designed as standard oil seals and it is too late to change our hardware. I was called in as a consultant and have to find a way to stop the leakage. The only thing I can think of is to increase the spring load in the seal which will cause more heat and friction.

Than you for your input.

 

[acp]

Sealguy,

In my opinion no standard oil seal work on this duty as the shaft dia is too high and speed is also on higher side.You will have to calculate PV value.

I suggest to go for specially designed oil seal or best way is to go for low cost/low duty mech. seal.

If you could let me know the cross sectional drg of seal area I can suggest you the solution.

Best Regards.

ACP

 

[azaday]

Hi there,
I just subscribed the eng-tips today. While surfing through I came across your issue and problem.
Well!... the problem that you have encountered is a common problem to the lip seal. At this point of time, there is no lip seal available that can 100% sealing especially with the mechine having high speed. Maybe when it is still new.
Looking at the operating speed you've mentioned, this might create thermal expansion of the shaft thus cause more friction and force agin the lip seal during operating mode. Not forgetting temperature increases direct to the seal that might cause the seal to be hardened. When you stop your mechine, for sure oil leak will occur.
I still believe M/seal might help you to solve your problem.
You can get help from AC PUNDE.

Best regards and have a nice day ahead.
Azaday

 

[Gibit]

There are air assisted Labyrinth seals that can definetly handle the speed and size of your application.