To avoid self-engagement in cone clutch, its semi-cone angle is always kept

Concept:

A cone clutch consists of inner and outer conical surfaces.

• The outer cone is keyed to the driving shaft, while the inner cone is free to slide axially on the driven shaft due to splines as shown in the figure.
• They are simple in construction and are easy to disengage. However, the driving and driven shafts must be perfectly coaxial for efficient functioning of the clutch.
• Cone clutches are friction clutches. 

• To avoid self-engagement in the cone clutch, its semi-cone angle is always kept greater than the angle of static friction.