Page 130 - Tribology in Machine Design

116 Tribology in machine design

and

hence,

where / is the coefficient of friction for driving conditions. This result is
illustrated in Fig. 4.19, where,

Numerical example
A cone clutch has radii of 127mm and 152mm, the semicone angle being
20°. If the coefficient of friction is 0.25 and the allowable normal pressure is
0.14MPa, find:
(a) the necessary axial load;
(b) the power that can be transmitted at 1000 r.p.m.

Solution

4.7. Rim clutch - A general purpose clutch, suitable for heavy duty or low speed, as in a line of
mechanism of operation shafting, is the expanding rim clutch shown in Fig. 4.20. The curved clutch
plates, A, are pivoted on the arms, B, which are integral with the boss keyed
to the shaft, S. The plates are expanded to make contact with the outer shell
C by means of multiple-threaded screws which connect the opposite ends of
the two halves of the ring. Each screw has right- and left-hand threads of fast
pitch, and is rotated by the lever L, by means of the toggle link E connected
to the sliding collar J. The axial pressure on the clutch is provided by a
forked lever, the prongs of which enter the groove on the collar, and, when
the clutch is disengaged, the collar is in the position marked 1.
Suppose that, when the collar is moved to the position marked 2, the