Browning Mounted Bearings Engineering - Kop-Flex - #9

Selection/Life Calculations Tapered Roller Bearings

Engineering

This section outlines the formula used to select bearing size or calculate expected bearing life for Browning Tapered Roller Bearings.

Tapered Roller Bearings are excellent for applications where radial and/or thrust load ratings exceed the capabilities of a ball bearing. Note: Maximum speeds are lower for Tapered Roller Bearings than Ball Bearings and Spherical Roller Bearings.

C = Basic Dynamic Rating (lbs.) 90,000,000 revolutions

P = Equivalant Radial Load (lbs.)

L10 = Rated Life (hrs.)

Fa = Applied Thrust Load

Fr = Applied Radial Load

K = Geometry Factory

n = Speed RPM

FIR = Bearing Internal Thrust

Use Step 1-4 at right and follow formula.

_L10= _(C/P)i0/3 _x ^{3000 hours x 500 RPM}

Select an initial bearing size, and calculate the expected L10 life. If the life is not acceptable, select another bearing size as appropriate and recalculate the L10. Continue this iterative process until an appropriate L10 life is obtained.

For applications where combined radial and thrust loads are present the equivalent radial load (P) must be calculated before applying the L10 life formula,

For applications with only a radial load present P=F_r Where F_r = Applied radial load in pounds

For applications with only a thrust load present, Consult EPT Mounted Bearing Tech Support

1. Calculate the bearing internal thrust reaction (FIR):

FIR= ^0.6 *^F K

- applied radial load

- factor K for 900/950 Series page 268 920/970 Series page 269

2. If the thrust load (F_a) is less than or equal to FIR, then calculate the equivalent radial load as follows:

P = (0.5 x F_r) + (0.83 x K x F_a)

3. If the thrust load (Fa) is greater than FIR then calculate the equivalent radial load as follows:

P = (0.4 x F_r) + (K x F_a)

4. Calculate the expected L10 life using the single row basic dynamic load rating. For 900/950 Series page 268.

For 920/970 Series page 269.

Lio _( single row load rating \^10/3 _x

3000 x 500 n

P

Multiply the theoretical life by the above factors to determine derated theoretical life.

1. See page 272, 273 for load and speed capabilities.

2. See General Engineering page 276.

See page 156 for trademark acknowledgments.