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Sample Calculations

Engineering

APPLICATION EXAMPLES:

EXAMPLE # 1Pure Radial LoadQuestion # 1: EXAMPLE # 2 Combined Radial and Thrust LoadQuestion # 1: What is the adjusted bearing life (L
na hours) for an VPS-239 BrowningBall Bearing with no shock conditions and the following applicationcriteria? What is the adjusted bearing life (L
na hours) for an VPS-239 BrowningBall Bearing with no shock conditions and the following applicationcriteria? Design Load (P)=1300 lbs.Speed (n)=1000 RPMShaft Size=2 Design Radial Load (F
r )=500 lbs.Design Thrust Load (F
a )=1000 lbs.Speed (n)=1000 RPM Shaft Size=2
7 /
16 InchesOperating Temperature=125°F
7 /
16 InchesOperating Temperature=125°F Solution: Solution: 1.Begin with the L
3 10 life formula: L
10 = (C/P) x 16667 n 1.Calculate F
a /F
r = 1000/500 = 22.Begin by calculating the Relative Axial Load (RAL):(From Table 3, page 267)RAL = F Look up the insert of an VPS-239 on page 6. From Table 4 onpage 269, the Basic Dynamic Radial Rating is 11,789 lbs.2.Apply the life adjustment factors:L
a = 1000 = 251 lbs. ND

Browning Mounted Bearings Engineering - 15937 (

11789

)

3 2 3.9690 L
10 = x 16667 = 12,430 hours 1300 1000 3.From Table 3 on page 263, interpolate RAL between200.10 and 300.15 and “e” between 0.30 and 0.34 to obtainan “e” value: 251 - 200.10 = e - 0.30Therefore e=.32300.15 - 200.10 0.34 - 0.30
na hours = L
10 x a
1 x a
2 x a
3 L
na hours = 12,430 x 1 x 1 x 0.456L
na hours = 5,700 hours * 4.From Table 3 on page 267, determine the value of “X”and “Y” through interpolation. Interpolate “e” between 0.30and 0.34 and “Y” between 1.45 and 1.31 because F Question # 2: What is the adjusted bearing life (L
10 hours) for an VPS-39 BrowningBall Bearing with moderate shock conditions and the same applicationcriteria from above?
a /F
r > e; 0.32 - 0.30 = Y - 1.45 0.34 - 0.30 1.31 - 1.45 Solution: ThereforeY = 1.38X = .565.Determine the equivalent radial load (P):P= (X F 1.From Table 2 on page 262: a
3 = 0.5 x 0.456.2.Re-Apply the life adjustment factors to the previouslycalculated L10 life:L
r ) + (Y F
a )= (0.56 x 500) + (1.38 x 1000) = 1660 lbs. L
na hours = L
10 x a
1 x a
2 x a
3 L
na hours = 12,430 x 1 x 1 x (0.5 x 0.456)L
3 na hours = 2,830 hours*
10 = (C/P) x 16667 n Question # 3: Look up the insert of an VPS-239 on page 6. From Table 4 onpage 267, the Basic Dynamic Radial Rating is 11,789 lbs. What is the bearing life (L
10 hours) for an PB-970NEx 2 7/16 TaperedRoller Bearing with no shock conditions and the same application criteriafrom above? 11789
3 L
NA =.456 x Solution: 1.Begin with the L
10/3 10 life formula: L
10 = (C/P) x 500 x 3,000 n Question # 2:

( )

x 16667 = 2720 hours16601000 What is the bearing life (L hours) for an PB-970NEx 2 7/16 TaperedRoller Bearing with no shock conditions and the same application criteriafrom above? 2.PB-970NEx 2 7/16 has 2 7/16” shaft size. From Table 13 x onpage 269, the Radial Rating is 9,030 lbs.
10 9030
10/3 Solution: L
10 =

( )

x 500 x 3,000 = 959,000 hrs. 1300 1000For moderate shock (from table 5) L 1.Find the K factor value from Table 13 on page 273, K = 1.51.2.Calculate the internal thrust reaction (FIR):FIR =0.6 x F
r -applied radial load K-factor K in Table 13
10 = .5* 959,000 = 480,000 hrs* Question # 4: What is the bearing life (L FIR =0.6 x 500 = 199 lbs. 1.51
10 hours) for an SPB-1000NEx 2 7/16 SphericalRoller Bearing with moderate shock conditions and the same applicationcriteria from above? 3.Since the thrust load is greater than the internal thrustreaction (FIR) use the following formula from page 268 to calculate the equivalent radial load. P = (0.4 x F Solution: 1.From Table No. 14 on page 270:L
r ) + (K x F
a ) P = (0.4 X 500) + (1.51 X 1000) = 1710 lbs.4.Caclulate the expected L 32,400
10/3 10 life using the single row rating.Single row rating = 5,220 lbs. This is found in Table 13 onpage 273.
10 = ? x For moderate shock (from Table 6 page 269)L10 = .5 x 754,000 = 37,000 hrs** Excessively high or low hours are not realistic in applications.

( )

x 16,667 = 754,000* hrs. 1300 1000 single row load rating
10/3 L
10 =

(

5220
10/3

)

x500 x 3000 Pn L
10 =

( )

x3000 x 500 = 61,900 hrs. 1710 1000

278

See page 156 for trademark acknowledgments.