Page 148 - Tribology in Machine Design

134 Tribology in machine design

so that

and

Applying this result to the evaluation of the initial tension, T 0

Under driving conditions,

Hence, adopting the notation for two unequal pulleys

Adding these results and equating to the initial extension due to T 0, we
obtain

This is a representation of the maximum permissible va'lue of T 0, if the
driving tension T 1 is not to exceed the specified maximum when the belt is
transmitting maximum power, and is based on the assumption that the
stress-strain curve for the belt is parabolic.

4.10.5. V-belt and rope drives
An alternative method of increasing the ratio of the effective tensions is by
the use of a V-grooved pulley. Figure 4.38, case (a), shows a typical groove
section for a cotton driving rope, with groove angle 2\l/ =45°. The rope does
not rest on the bottom of the groove, but only on the sides, the wedge action