V belt drive

design procedure and steps to follow before manufacturing belt drive. particularly V - Belt drive

1. V- belt drive Mohammed Rajpurwala – 150050119540 Abhay pathak – 150050119535

2. CONTENT INTRODUCTION STANDARD CROSS SECTION OF V-BELTS ADVANTAGES AND LIMITATIONS APPLICATIONS NOMENCLATURE SELECTION OF V-BELTS FROM MANUFACTURER’S CATALOGUE

3. INTRODUCTION The cross section of the V-Belt, which is trapezoidal is as shown in background. It consists of three parts : 1. Central load carrying textile, Nylon or steel cords; 2. Surrounding rubber to transmit pressure from cords to side walls; 3. Outer fabric and rubber cover. The V-belts run in grooved pulleys known as sheaves.

4. STANDARD CROSS SECTION OF V-BELTS Belt section Width(mm) Thickness(mm) Min. pitch dia of pulley(mm) Correction (mm) Z 10 6 85 30 A 13 8 75 36 B 17 11 125 43 C 22 14 200 56 D 32 19 315 79 E 38 23 500 92 Z A B C D E

5. ADVANTAGES Used to transmit power over long distances. Due to wedging action, V-belt drives can transmit large power as compared to the flat belt drives. It permits high reduction ratio, even up to 7:1. The sli p is negligible in V-belt drives due to wedging action.

6. DISADVANTAGES The efficiency of V-belt drives is lower than that of the flat belt drives. It ranges from about 80 to 96%. They are costlier as compared to flat belt drives. APPLICATIONS V-belt s are used with electric motors to drive blowers, compressors, machine tools, farm and industrial m/c. Used to drive the accessories of automotive and most other IC engines.

7. NOMENCLATURE Pitch width ( Wp ) It is the width of the belt at its pitch zone. Nominal top width ( W ) It is the top width of the trapezium outlined on the cross-section of the belt. Nominal height ( T ) It is the height of the trapezium outlined on the cross-section of the belt. 4. Angle of belt ( A ) It the included angle obtained by extending the sides of the belt. The standard value of A is 40 degree. 5. Pitch length ( Lp ) It is the length of the pitch line of the belt. W Wp A T

8. SELECTION OF V-BELTS FROM MANUFACTURER’S CATALOGUE The data available is: Power to be transmitted, P; Input & output speeds and Approximate centre distance. Select the service factor or load correction factor ‘ Fa ’ for the given application. 3. Calculate the design power ‘Pd’ Pd = Fa * P

9. Select the type of V-belt cross-section : The selection of type of V-belt cross-section depends upon two factors, namely, the design power and the speed of faster pulley. Select the standard pulleys : calculate the required speed ratio and select the pair of pulleys from the standard list so as to give the speed ratio as closer to the required speed ratio as possible. Calculate pitch length of belt : L = 2C + π ( D+d )/2 + 1/4C*(D-d)2

10. Select nearest standard pitch length of the belt from manufacturer’s catalogue and calculate the exact centre distance : C = A + (A – B2)1/2 Find the power rating ‘kW’ of the selected V-belt from the manufacturer’s catalogue. Calculate arc of contact for the smaller pulley and find arc of contact correction factor ( Fd ). Find belt length correction factor ( Fc ). C alculate the modified power rating (kW)M of the V-belt. (kW)M = (kW) * Fd * Fc

11. Find the number of belts required : z = Design power / modified power rating of the belt = Pd / (kW)M = P * Fa / (kW) * Fd * Fc Thank you