towards the flywheel and pressing the longer ends of the levers inward. The levers are forced to turn on their suspended pivot and the pressure plate moves away from the flywheel by the knife edges, thereby compressing the clutch springs. This action removes the pressure from the clutch plate and thus moves back from the flywheel and the driven shaft becomes stationary. On the other hand, when the foot is taken off from the clutch pedal, the thrust bearing moves back by the levers. This allows the springs to extend and thus the pressure plate pushes the clutch plate back towards the flywheel.
p = Intensity of axial pressure with which the contact surfaces are held together,
r1 and r2 = External and internal radii of friction faces, and
µ = Coefficient of friction.
We know that area of contact surface or friction surface,
=2 π r.dr
∴ Normal or axial force on the ring,
δW = Pressure × Area = p × 2 π r.dr
and the frictional force on the ring acting tangentially at radius r,
Fr = µ.δW = µ.p × 2 π r.dr
∴ Frictional torque acting on the ring,
Tr= Fr × r = µ.p × 2 π r.dr × r = 2 π × µ .p.r.r dr