Sr. No. 
Particular 
Frictional torque 

Uniform Pressure 
Uniform Wear 

1 
Flat Pivot Bearing 
\(\frac{2}{3}\mu WR\) 
\(\frac{1}{2}\mu WR\) 
2 
Conical Pivot Bearing 
\(\frac{2}{3}\mu WR.\csc \alpha \) 
\(\frac{1}{2}\mu WR.\csc \alpha \) 
3 
Trapezoidal Conical Pivot Bearing 
\(\frac{2}{3}\mu W.\csc \alpha \left[ {\frac{{r_1^3  r_2^3}}{{r_1^2  r_2^2}}} \right]\) 
\(\frac{1}{2}\mu W.\csc \alpha \left( {{r_1} + {r_2}} \right)\) 
4 
Flat Collar Bearing 
\(\frac{2}{3}\mu W\left[ {\frac{{r_1^3  r_2^3}}{{r_1^2  r_2^2}}} \right]\) 
\(\frac{1}{2}\mu W\left( {{r_1} + {r_2}} \right)\) 
5 
Single Disc or Plate Clutch 
\(\frac{2}{3}\mu W\left[ {\frac{{r_1^3  r_2^3}}{{r_1^2  r_2^2}}} \right]\) 
\(\frac{1}{2}\mu W\left( {{r_1} + {r_2}} \right)\) 
6  Cone Clutch  \(\frac{2}{3}\mu W.\csc \alpha \left[ {\frac{{r_1^3  r_2^3}}{{r_1^2  r_2^2}}} \right]\)  \(\frac{1}{2}\mu W.\csc \alpha \left( {{r_1} + {r_2}} \right)\) 