p = N / πr2;
(60)
and, introducing this value into equation 59, the moment of friction of the flat pivot is found to be
2⁄3ƒNr
(61)
or two-thirds of that of a cylindrical journal of the same radius under the same normal pressure.
The friction of a conical pivot exceeds that of a flat pivot of the same radius, and under the same pressure, in the proportion of the side of the cone to the radius of its base.
The moment of friction of a collar is given by the formula—
| 2⁄3 ƒN | r3 − r′3 | , |
| r2 − r′2 |
(62)