Example 1. A centrifugal clutch is to transmit 15 kW at 900 r.p.m. The shoes are four in number. The
speed at which the engagement begins is 3/4th of the running speed. The inside radius of the pulley rim
is 150 mm and the centre of gravity of the shoe lies at 120 mm from the centre of the spider. The shoes
are lined with Ferrodo for which the coefficient of friction may be taken as 0.25. Determine:
1. Mass of the shoes, and
2. Size of the shoes, if angle subtended by the shoes at the centre of the spider is 60° and the pressure
exerted on the shoes is 0.1 N/mm2.
Solution. Given: $P= 15 kW = 15 \times 10^3 W$; $N= 900 r.p.m.$ or $= 25 \times 900/60 = 94.26 rad/s$; $n=4$;
$R= 150 mm = 0.15 m$; $r= 120 mm = 0.12 m$; $\mu = 0.25$
Since the speed at which the engagement begins (i.e. $\omega_1$) is 3/4th of the running speed (i.e. $\omega$),
therefore
