Concept explainers
A 6-in-widc polyamide F-l flat belt is used to connect a 2-in-diameter pulley to drive a larger pulley with an angular velocity ratio of 0.5. The center-to-center distance is 9 ft. The angular speed of the small pulley is 1750 rev/min as it delivers 2 hp. The service is such that a service factor Ks of 1.25 is appropriate.
- (a) Find Fc, Fi, (F1)a,. and F2, assuming operation at the maximum tension limit.
- (b) Find Ha, nfs, and belt length.
- (c) Find the dip.
(a)
The value of
The value of
The value of
The value of
Answer to Problem 2P
The value of
The value of
The value of
The value of
Explanation of Solution
Refer the Table
Refer the Table 17-4, “Pulley correction factor
Write the expression for weight of the foot of belt.
Here, width of belt is
Write the expression for velocity ratio.
Here, the velocity of the driven pulley is
Write the expression for contact angle for smaller pulley.
Here, the center distance between pulley is
Write the expression for velocity of the driving pulley.
Here, diameter of the driving pulley is
Write the expression for centrifugal tension
Here, weight of the belt per
Write the expression for torque
Here, the power delivered is
Write the expression for actuating force on tight side of the belt.
Here, the width of the flat belt is
Write the expression for difference in tension in tight side and slack side.
Write the expression for tension in slack side of belt.
Write the expression for initial tension in belt.
Conclusion:
Substitute
Substitute
Substitute
Substitute
Substitute
Thus, the value of
Substitute
Substitute
Thus, the value of
Substitute
Substitute
Thus, the value of
Substitute
Thus, the value of
(b)
The value of
The value of
The belt length.
Answer to Problem 2P
The value of
The value of
The belt length is
Explanation of Solution
Write the expression for the transmitted horse power.
Here, the velocity of the driving pulley is
Write the expression for factor of the safety.
Here, the transmitted horse power is
Write the expression for contact angle for bigger pulley.
Here, the center distance between pulley is
Write the expression for the length of the belt.
Conclusion:
Substitute
Thus, the value of
Substitute
Thus, the value of
Substitute
Substitute
Thus, the belt length is
(c)
The dip of the belt.
Answer to Problem 2P
The belt dip is
Explanation of Solution
Write the expression for belt dip.
Here, the center distance between pulley is
Conclusion:
Substitute
Thus, the belt dip is
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Chapter 17 Solutions
Shigley's Mechanical Engineering Design (McGraw-Hill Series in Mechanical Engineering)
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