1. Design and Electromechanical systems
Dr Jason Matthews
UFMF
Design and Electromechanical systems
Tutorial 6 - Solutionsocess

2. SKF.com – Bearing calculator
2/22/2019
UFMF

3. Calculating bearing life
Where:
P = Load on bearing in KN
p = 3 for ball bearings, and 10/3 for roller bearings
L = Life in number of millions of cycles
C = Load rating
2/22/2019
UFMF

4. Equivalent Dynamic Load (P)
Standard equation for computing an equivalent radial load
Fr= Radial force on bearing(N)
Fa= Axial force on bearing(N)
X and Y are given in manufacturers data books
2/22/2019
UFMF

5. Example 1
Fr=15kN
Select a ball bearing having an internal diameter of 30mm suitable for the axial force of 15kN as shown. We want a life expectancy of 60million revolutions, Considering that a1=a2=a3=1
In this case X=1 and Y=0

6. The Max C from the table is 43.6 kN …..what should I do now

7. Solutions Change from single row deep groove to double row deep groove
Change to Cylindrical roller bearings
Change the internal diameter ( if it is possible)
Use two bearings instead of one ( not the best option)

8. P= 15 kN, then
No more iteration needed

9. Example 3
Select a ball bearing having an internal diameter of 30mm suitable for two axial forces of 5kN as shown. We want a life expectancy of 60million revolutions, Considering that a1=a2=a3=1
Fr1=5kN
Fr2=5kN
It is clear that in this case Fa=0 then X= 1,

10. Example 3
Fa=15kN
Select a Thrust bearing having an internal diameter of 40mm suitable for the axial force of 15kN as shown. We want a life expectancy of 60million revolutions, Considering that a1=a2=a3=1
It is clear that in this case Fr=0 then Y= 1,