
Concept explainers
(a)
Design a Gates Rubber V-belt drive to transmit power from the motor to the compressor flywheel.
(a)

Explanation of Solution
Consider a
Write the expression for center to center distance between pulleys.
Here, length of the belt is
Write the expression for contact angle for smaller pulley.
Here, the center distance between pulley is
Write the expression for contact angle for bigger pulley.
Here, the center distance between pulley is
Write the expression for contact correction factor
Here, the contact angle for smaller pulley is
Write the expression for velocity of the smaller pulley.
Here, the rotational speed of the smaller pulley is
Write the expression for allowable power per belt
Here, the angle of wrap correction factor is
Write the expression for design power.
Here, nominal power is
Write the expression for number of belts.
Write the expression for torque
Here, the design power is
Write the expression for difference in tension in tight side an slack side of the belt.
Here, the torque is
Write the expression for centrifugal tension
Here, the speed of the belt is
Write the expression for initial tension in belt.
Here, the coefficient of the friction is
Write the expression for tension in tight side of the belt.
Here, the centrifugal tension in the belt is
Write the expression for tension in slack side of the belt.
Here, the difference in tension in tight side an slack side of the belt is
Write the expression for factor of the safety.
Here, allowable power per belt is
Write the expression for number of the belt passes.
Here, belt parameter is
Write the expression for the belt life.
Conclusion:
Substitute.
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Thus, the factor of the safety is
Substitute
Thus, the belt life in passes is
Substitute
Thus, the tool life in hour is
Thus, the selected belt is C-270.
(b)
Whether the cutting of the V-belt grooves in the flywheel is avoided by using a V-flat drive.
(b)

Answer to Problem 20P
The cutting of the V-belt grooves in the flywheel cannot be avoided by using a V-flat drive.
Explanation of Solution
Write the expression for the fully developed friction torque on the flywheel using the flats of the V-belts.
Here the friction coefficient of flat on flywheel is
Write the expression for the flywheel torque.
Here, the torque constant is
Conclusion:
Substitute
Substitute
Since, the torque produced by V-belt is lower than the torque given by flywheel. Thus, he cutting of the V-belt grooves in the flywheel cannot be avoided by using a V-flat drive.
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Chapter 17 Solutions
Shigley's Mechanical Engineering Design (McGraw-Hill Series in Mechanical Engineering)
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