Mechanical Engineering Design - Journal Bearings

This page gives the comparative results of using the Raimondi and Boyd charts with the Java applet for determining characteristics of parallel shaft journal bearings with hydrodynamic lubrication.
d, mm 20 20 20 100 100 100 100 40 40 40
length 5 5 5 100 100 100 100 40 40 40
c 0.005 0.005 0.005 0.05 0.05 0.05 0.05 0.04 0.04 0.04
Load 10000 10000 10000 100000 100000 100000 100000 2500 2500 2500
Revs/s 100 100 100 20 20 20 20 30 30 30
Viscosity 0.01 0.01 0.01 0.1 0.1 0.1 0.1 0.0275 0.0275 0.0275
circ ints. 72 180 180 180 360 180
length ints. 16 16 32 20 100 16
Iterations 1000 1000 1000 5000 40000 2000
Oil hole dia, mm 0.5 0.5 5 5 5 4
Oil press, N/m2 100000 100000 100000 100000 100000 100000
ecc. ratio 0.925 0.925 0.93 0.47 0.47 0.47 0.47 0.59
Sommerfeld No. 0.04 0.04 0.04 0.2 0.2 0.2 0.2 0.132 0.132 0.132
Results: Chart results Applet results Applet results Chart results Applet results Applet results Applet results Chart results Applet results Applet results
Friction force, N 10.4 10.76 16.18
Attitude angle 17o 21.8 19 58.5 58.5 59.4 58.9 52 52
Resultant N 8600 9769 80048 99339 99923 2554
Av. Press, MPa 86 97.7 8 9.93 9.99 1.596
Coef. of Friction 0.0011 0.00104 0.001075 0.0046 0.0045 0.00449 0.00448 0.0066 0.00647
Friction power W 69.1 65.5 67.6 2890 2820 2820 2815 61
Oil flow l/s 0.0015 0.000146 0.000146 0.02 0.0148 0.01477 0.01478 0.00358
p/pmax 0.155 0.153 0.153 0.46 0.454 0.431 0.461 0.4054
Theta po, o 23 22 21.6 85 84.5 79.4 83.9 76 70
Theta pmax, o 7.6 7 7.6 17.6 16.5 17.4 16.9 18 18

These results (and others) tend to show that with a reasonable number of circular and longitudinal intervals, 2000 iterations are normally sufficient to give answers which are converged within close limits, certainly closer than the limits for much of the real data input for the computations.

David J Grieve, CEng, MIMechE, updated: 7th February 2015, 17th December 2009