Page 154 - Tribology in Machine Design

140 Tribology in machine design

Now, it is appropriate to consider the curved brake block in action. Three
cases shall be discussed.

(/) Uniform pressure
Figure 4.42 represents the ideal case in which the block is pivoted at the
point of intersection C of the resultant R^ and the line of symmetry. Since
/? = (/> and the pressure intensity p is constant, eqns (4.115) and (4.116)
apply, so that

resisting torque
Figure 4.42

and

also

so that

(ii) Uniform wear

Referring to Fig. 4.42, it is assumed that the vertical descent 6 is constant for
all values of 0. Hence, measuring 0 from the line of symmetry,
normal wear at position 0 = <5cos0

and applying the condition for uniform wear, pa is proportional to <5cos 0
or

Applying the integrals as in the preceding case