 Hello everyone, Myself Sachin Rathod working as assistant professor in mechanical engineering department from Walsh Instruct Technology, Solar Pood. Today we will discuss the selection of the belt part 10 under the subject of machine design one. The learning outcome of this session is the students will able to design the V belt from the manufacturing catalog. So, just we will consider one problem statement from which we will get the design procedure how to select the V belt from the manufacturing data book. So, this is a problem statement. A V belt is required for 15 kilowatt power having the speed of 1440 rpm electric motor which drives a centrifugal pump running at 360 rpm for a service of 24 hours per day means we have to convert the speed from 1440 rpm to 360 rpm on which the centrifugal pump is mounted. So, here the application is centrifugal, we have to run the centrifugal pump from the electric motor. From space considerations, the center distance should be approximately 1 meter, the distance between input shaft and the output shaft that is nothing but the distance between electric motor shaft and the centrifugal pump shaft is 1 meter. So, we have to determine the belt specification number of the belt, the correct center distance and the pulley diameter. So, these are the given data 15 kilowatt power speed of the input and the output shaft that given us the service we have to use for the 24 hours per day centrifugal pump and the center distance is 1000 mm. So, the step number 1 is to determine the correction factor according to the service that is F A from the design data book. So, from these tables we have to find out the service factory F A. So, as they had given us the 5 kilowatt powers the speed of the input shaft is 1440 that is a faster pulley and the fan service is 24 hours per day. So, according to this we have to find out the service factory F A. So, we have to run the centrifugal pump and it is running for the 24 hours per day. So, you have chosen the factor service factory is 1.3. So, the second step we have to find out the design power, design power is calculated by using the equation design power is equal to F A into transmitted power. So, the F A is 1.3 and the transmitted power. So, step number 1 determine the correction factor according to the service from the table. From which we have to find out the service factory F A. So, this is a given data on the power is 15 just correct that the power is 15 the input speed is 1440 rpm and the fan service is 24 hours per day. So, by considering the 50 kilowatts so, it comes over 7.5 so, it comes under the medium duty and the service we have to use for 24 hours per day. So, we can see like the service factor is 1.3. So, in the step number 2 find out the design power. Design power for the V-belt we can calculate by using the equation F A into transmitted power. So, transmitted power is 15 into the service factor is 1.3. So, you are getting the design power is 19.5 kilowatt. Step number 3 determine the cross section of the belt based on the design power and the high speed of the shaft in the rpm from the table. So, this is a table from which we have to select the proper type of the cross section of the belt. So, in these tables we have observed that there are the 5 types of the belts are available A, B, C, D and E. So, based on the high speed and the design power we have to select proper cross section of the belt. So, the horizontal line on the horizontal axis indicating the power and the vertical line indicating the speed of the faster pulley. So, as the design power is 19.5 kilowatt. So, this is a line for the horizontal line indicating the design power just I have drawn one line which is passing from 19.5 and the speed of the faster pulley is 1440 rpm just I have drawn the horizontal line. So, intersecting is at this junction. So, this is we have to use the B cross section belt. So, which is ranging from this line. So, I have selected the cross section of the belt is B type. So, the cross section of V belt is B type. So, in the next steps the dimension of the cross section standard cross section belt that is a we have chosen as a B belt. So, the pitch width, nominal width and the nominal heights are we have to take from this table. Also, the recommended minimum pitch diameter of the pulley is 200 mm and the permissible minimum pitch diameter of the pulley is 125. So, you can select the value of the diameter of the smaller pulley which is ranging in between these two or you can select 125 or 200 as a diameter of the smaller pulley. So, for the B section belts the value is ranging from these two value. So, you can consider the diameter of the smaller pulley as 200 mm. Now, in the next steps you have to calculate the diameter of the larger pulley by knowing the equations n 1 d is equal to n 2 d. So, these equations we are getting from the relation the speed of the shaft and the diameter of the pulley that speed is inversely proportional to the diameter therefore we are getting n 1 by n 2 is equal to capital D by small d. So, from that equations we are getting this. So, just put the value of n 1, n 2 and small d you will get the value of capital D. So, capital D is equal to 800 mm. So, from the standard data books you have to check out this data. So, we have selected the B belt 800 is available. So, you can select the value of the capital D is 800 mm. So, in the step number 5 calculate the pitch length of the belt. So, in the step number 5 calculate the pitch length of the belt. So, pitch length is calculated by using this equation as the data we are knowing capital D small d and c put that value you will get the length of the belt. So, we have to check out the standard pitch length from this table. So, for B section belt you can select the pitch length of the belt is 3600 mm. In the step number 7 find out the correct central distance c by considering the standard pitch length. So, you can pause this video and you can think about this why it is necessary to find out again the center distance that is called as a corrected center distance. So, you can think about this. So, if you put this value in that equations you will get the corrected center distance is 968.118 mm. In the step number 8 determine the correction factor for the belt pitch length fc from the given manufacturing data. So, this is a table from which we have to calculate the correction factor fc. So, as we are using the B belt and the length of the belt is 3600. So, the correction factor fc is 1.10. So, I have selected fc is equal to 1.10. In the step number 9 calculate the angle of contact for the smaller pulley. So, by using this equation we have to calculate the wrap angle put the value of capital D small d and c you will get the wrap angle alpha s is equal to 143.89 degree. So, you have to find out the arc of contact factor fd from the manufacturing data book. So, this is a table from the manufacturing data book calculate the value of fd. So, we are getting the value of the fd is 0.905 as the alpha s if you observe that alpha s which is ranging in between these two 142 and 145. So, the factor should be the in between these two value. So, you can consider the factor is 0.905. So, the step number 11 find the power rating of the belt that is a power transmitting capacity of the belt PR. So, as they are given us the speed of the faster pulley is 1440 rpm and the diameter of the smaller pulley is 200 rpm and the B section bed having the speed ratio is 4. So, speed ratio is nothing but the speed of the input shaft divided by speed of the output shaft we are getting as a 4. So, by using this data you have to find out the power rating. So, the speed of the faster shaft is 1440 rpm. So, we are getting the diameter of the smaller pulley is 200 mm. So, it is the value is 5.90. Again, we have to consider the speed ratio is a 4. So, the speed ratio is 2 and over the value is 0.46. So, 5.90 plus 0.46, 5.90 plus 0.46 you will get the power rating as 6.36 kilowatt. So, in the last step, step number 12, determine the number of the belt. So, the number of the belts we are getting by using this equation. So, just put this value you will get number of the belt is 3.07. So, you can take the whole number as 3 belts. So, the 3 belts we required for that power transmission. So, you have the final design solution will be obtained as the diameter of the pulley small d is equal to 200 mm, diameter of the larger pulley is 800 mm, diameter or the belt specification is B3600 LP V belt. Number of belt required is 3, the center distance is 968.118 mm. I have taken this reference as a design of machine element book which is author having VB Bhandari. Thank you.