Diameter of pulley=400 mm, Diameter of smaller pulley=250 mm, Distance between two pulleys=2 m, Coefficient of friction between smaller pulley surface and belt = 0.4, Maximum tension when the belt is on the point slipping=1200 N.

Find the power transmitted at speed of 10 m/s. it is desired to increase the power. Which of the following two methods you will select?

1. Increasing the initial tension in the belt by 10 percent.
2. Increasing the coefficient of friction between the smaller pulley surface and belt by 10 percent by the application of suitable dressing on the belt.

Find also, the percentage increasing in power possible in each case.

Subject: Kinematics of Machinery

Topic: Belts, Chains and Brakes

Difficulty: Medium

Given :- $d_{1}$ =400 mm =0.4m; $d_{2}$ =250 mm= 0.25 m; x= 2 m; $\mu$= 0.4;

T=1200N; ν =10m/s.

Power transmitted

We know that for an open belt drive,

$\sin\alpha=\frac{(r_{1}-r_{2})}{x}=\frac{(d_{1}-d_{2})}{2x}$ =(0.4+0.25)/(2×2) = 0.0375 or $\alpha$ = 2.150

Angle of contact, $\theta$ = 180$^{\circ}$ -2$\alpha$= 1800-(2×2.150) = 175.70

=175.7×($\pi$/180) =3.067 rad. …