1. Journal bearing, Ball bearing
Experiment 7
Journal bearing, Ball bearing

2. Journal bearing and Ball bearing

4. Lubrication oil
Lb-sec/in2

5. Journal bearing

7. Revolutions per second
Petroff equation
viscosity
Radius of bearing
Friction force
Revolutions per second
Length of the bearing
Radial clearance

9. Average pressure in the bearing
Hydrodynamic theory of lubrication
Sommerfeld number
Average pressure in the bearing

11. Example 1
A shaft runs at 1800 rpm in a 2x2 in2 bearing at a stable temperature of 150oF. The oil used is SAE 20, the load is 2000 lb, and Cr =0.001in. Find friction force and hp.
Sol.
From Fig. 8.11(b), fr/Cr=3.6 from Fig.8.11(a) h0/Cr=0.44. therefore, h0= in.

13. Ball and roller contact bearing

14. Static and dynamic load

15. Note: The reliability for C10 is 0. 9
Note: The reliability for C10 is 0.9. a=3 for ball bearing, 10/3 for roller contact bearing

16. Combined Radial and thrust Loading

19. Example 2
A single roll deep groove ball bearing( d=20mm, D=42mm, B=12mm.) running at 700 rpm, the load is 10 kN and in radial direction. Find the life of the bearing.
Sol.
From the catalog the bearing has a dynamic rate load of 9.4kN.

20. Mounting and enclosure

23. Experiment 7-1
Determine the power need to overcome the friction of the journal bearing for a optical disk spindle motor. The internal diameter of the bearing is 0.1 in, length is 0.2 in. and the clearance is in. The lubrication oil is light turbine oil. The rotating speed is 8000rpm. If the operating temperature is 140oF, find the power needed to overcome the friction of the bearing.

26. Experiment 2
If the break of a motorcycle has a bearing which loaded by a dynamic force. The style of the bearing is TPI d=12mm,D=32mm. The required life of the break is hr, find the maximum design load of the bearing. Please Draw a cross section (with dimensions) of the assembly of the bearing (including the mounting arrangement).