Page 73 - Tribology in Machine Design

60 Tribology in machine design

and the virtual coefficient of friction is then given by

Figure 2.25 The graph of Fig. 2.25 shows the variation of/r/c for varying values of e/c.
The value of/when e = e/c = 0.7 occurs at the transition point from film to
boundary lubrication, and at this point / may reach an abnormally low
value. Thus,ifc/r= l/1000;/ min =0.0009. It should be noted that this value
of/mm relates to the journal. If/ r is the virtual coefficient of friction resulting
from the reaction torque M r on the bearing, then

Equation (2.156) is the result of the subtraction of eqn (2.155) from eqn
(2.152). For the value £ = e/c=0.7 the virtual coefficient of friction for the
bearing is then

2.13.12. The Sommerfeld diagram

Rewriting eqn (2.147) the load per unit length of journal is

Using the Sommerfeld notation