Journal Bearing Lubrication Analysis

The following procedure leads to a complete lubrication analysis which forms the basis for the bearing design.

1) Diameter of bearing d.
This is usually determined by considering strength and/or deflection requirements for the shaft using principles of strength of materials.
2) Length of bearing L
This is determined by an assumed l/d ratio in which l may or may
not be equal to the overall length, L (See Step 6). Bearing pressure and the possibility of edge loading due to shaft deflection and misalignment are factors to be considered.
In general, shaft misalignment resulting from location tolerances and/or shaft deflections should be maintained below 0.0003 inch per inch of length.
3) Bearing pressure pb
The unit load in pound per square inch is calculated from the formula:
pb =W/Kld
where K=1 for single oil hole
K=2 for central groove
W=load, pounds
l =bearing length
d=journal diameter, inches