centreugal tension in belt

CENTREUGAL TENSION IN BELT

• Since the belt continuously runs over the pulley, therefore some centrifugal force is caused. The tension caused by centrifugal force is called centrifugal tension.

• The effect of centrifugal tension is to increase the tension on both tight and slack sides. 

• At lower speeds the centrifugal tension is very small. But at higher speeds, the centrifugal effect is considerable and thus should be taken into account.

Derivation: Consider a short element AB of belt, as shown in Fig.8.23.

Let

m = Mass per unit length of belt in kg/m,

v = Linear velocity of belt in m/s,

r = Radius of the pulley in metres,

TC = Centrifugal tension on tight and slack sides of element in newtons, and

FC = Centrifugal force on the element in newtons.

Centrifugal force acting on the belt element AB is given by

FC = mass of element × acceleration

= (length of element × mass per unit length) × acceleration

Resolving the forces vertically, we get

Thus it may be noted that centrifugal tension does not depend on the radius of pulley. Thus, irrespective of radii of driver and driven pulleys, the centrifugal tension is same at both the pulleys.

1. Maximum Tension in Belt Drive

We know that the effect of centrifugal force acting on belt is to introduce centrifugal tension Tc on both sides of the pulley.

Thus, maximum tension to which the belt can be subjected due to centrifugal tension,

2. Stress Induced in Belt

We know that Tmax = Maximum stress x Cross-sectional area of belt

where Tmax = Maximum tension in the belt in newtons,

σ = Maximum safe stress in the belt in N/m2,

b = Width of the belt in metres, and

t = Thickness of the belt in metres.

Note 

The centrifugal tension has no effect on the power transmitted.