Answer to Question #119131 in Mechanical Engineering for Hilal Nasser Nasser

Question

A multi disc clutch, steel on bronze is to transmit 20 kW at 1440 rpm. The clutch is to be operated in oil with the coefficient of friction 0.08 and the average pressure is 0.3 MPa. Space limitation permits only 230 mm as outside diameter of the clutch. Assuming uniform pressure, determine: (i) Actual axial force required (W’) (ii) Actual maximum pressure (p’max) (iii) Actual average pressure (p’ave) Ratio of (Ri/Ro) can be chosen between 0.5 and 0.75 suitably and logically

Answer 1

P=20 kW, N=1440 rpm, coefficient of friction=0.08 , Average pressure = 0.3 MPa

Ri/Ro=0.5/0.75 ,

So, axial force required

(i)

(ii) We know that, for power transmitted

T= 132696.3 N-mm

Dm=

Using uniform wear theory

132696.3= 0.5

n= 7.5 it will be even number = 8

number of steel disc= 4

number of bronze disc= 4+1= 5

Average pressure

(ii) For average pressure

p= 0.338 MPa

(iii)For actual maximum pressure

p= 0.422 MPa