Page 128 - Tribology in Machine Design

114 Tribology in machine design

Numerical example
If, in the previous example, the clutch surfaces become worn so that the
intensity of pressure is inversely proportional to the radius, compare the
power that can be transmitted with that possible under conditions of
uniform pressure, and determine the greatest intensity of pressure on the
friction surfaces. Assume that the total axial force on the clutch, and the
coefficient of friction are unaltered.

Solution

under conditions of uniform pressure p=0.07MPa, thus

4.6. Cone clutch - The cone clutch depends for its action upon the frictional resistance to
mechanism of operation relative rotation of two conical surfaces pressed together by an axial force.
The internal cone W, Fig. 4.18, is formed in the engine fly-wheel rim keyed
to the driving shaft. The movable cone, C faced with friction lining material,
is free to slide axially on the driven shaft and, under normal driving
conditions, contact is maintained by the clutch spring S. The cone C is
disengaged from frictional contact by compression of the clutch spring
through a lever mechanism. During subsequent re-engagement the spring
force must be sufficient to overcome the axial component of friction
between the surfaces, in addition to supplying adequate normal pressure for
driving purposes.
Referring to Fig. 4.19, let
Q e =the total axial force required to engage the clutch,
p = the permissible normal pressure on the lining,
a = the semi-angle of the cone,
Figure 4.18 / e = the coefficient of friction for engagement.