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Viscosity Factors for Tapered Roller Bearings

Viscosity Factors for Tapered Roller Bearings

Viscosity Factors for Tapered Roller Bearings

Hi Guys,

I'm at a bit of a dead end with regards to understanding viscosity factor formulas for tapered roller bearings. A guy who used to work for the company I'm at did a spreadsheet-based calculator on Excel which calculated the L10 life of tapered roller bearings. It takes viscosity into account, and he has used a range of different formulas for the calculations. They are as follows:

FV - VISCOSITY (Formula: 0.5767 x viscosity (CSt)^0.133
TA - SPEED OPTION 1 BRG A (Formula: KT x Engine Speed^0.2)
TA1 - SPEED OPTION 2 BRG A (Formula: 0.1405 x shaft speed^0.38)
FTA - RESOLVES TA & TA1 (Formula: If shaft speed > NC, TA, TA1)
TB1 - SPEED OPTION 1 BRG B (Formula: KT x Shaft Speed^0.2)
TB1 - SPEED OPTION 2 BRG B (Formula: 0.1405 x shaft speed^0.38)
FTB - RESOLVES TB & TB2 (Formula: If shaft speed > NC, Speed option 1 Bearing B, Speed Option 2 Bearing B)

I've attached a small screenshot of the viscosity factors in question.

Many Thanks.

RE: Viscosity Factors for Tapered Roller Bearings

I think I'd start with the info on pages 4 thru 10 here.


I'd kind of expect your formula is simplified for a fairly small range of bearing sizes and speeds.

i'll try to dig up my bearing text books.

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