An open, flat belt drive is required to transmit 25 kW at 200 rpm. The diameters of (14)

the driving pulley and the driven pulley are 200mm and 150 mm, respectively. The angle of contact on the driven pulley is 176° and the centre distance between the parallel shafts is 1,5 m. Use a coefficient of friction of 0,37 to calculate the following:
6.1
Ratios of the belt tensions.

1 answer

To calculate the ratios of the belt tensions in an open flat belt drive system, we can use the following formula derived from the belt tension equation:

\[ \frac{T_1}{T_2} = e^{\mu \theta} \]

where:

  • \( T_1 \) = tension in the tight side of the belt
  • \( T_2 \) = tension in the slack side of the belt
  • \( \mu \) = coefficient of friction
  • \( \theta \) = angle of contact in radians

Given data:

  • \(\mu = 0.37\)
  • Angle of contact for the driven pulley = 176° (we need to convert this to radians).

First, convert the angle of contact from degrees to radians:

\[ \theta = 176° \times \frac{\pi}{180} = \frac{176 \pi}{180} \approx 3.073 , \text{radians} \]

Now, substitute the values of \( \mu \) and \( \theta \) into the tension ratio formula:

\[ \frac{T_1}{T_2} = e^{0.37 \times 3.073} \]

Calculating \(0.37 \times 3.073\):

\[ 0.37 \times 3.073 \approx 1.137 \]

Now, applying the exponential function:

\[ \frac{T_1}{T_2} = e^{1.137} \approx 3.115 \]

Thus, the ratio of the belt tensions is approximately:

\[ \frac{T_1}{T_2} \approx 3.115 \]

Conclusion

The ratio of the belt tensions \( T_1 \) to \( T_2 \) is approximately 3.115.