Question

In a multiple–disc clutch, the axial intensity of pressure is not to exceed 0.2 MPa. The inner radius of the discs is 100 mm and is half the outer radius. The axial force per pair of contact surfaces in N is 
1. 2000 π 
2. 3000 π 
3. 4000 π 
4. 6000 π 

Answer 1

Correct Answer - Option 3 : 4000 π 

Concept: 

From uniform wear theory, axial force is given by,

\(W=2π C(r_0-r_i)\)

When the intensity of pressure is maximum at the inner radius : \(C=P_{max}× r_i\)

When the intensity of pressure is minimum at the outer radius: \(C=P_{min}× r_o\)

W = 2π (P ri) (r0 - ri)

Calculation:

Given P_max = 0.2 MPa, r_i = 100 mm = 0.1 m, r_o = 200 mm,

W = 2π (0.2 × 10⁶ × 0.1)  (200 - 100) × 10^-3 = 4000 π