 Hello everyone, myself Sachin Rathod working in mechanical engineering department from Walton Institute of Technology, Sallapur. Today, we are dealing with the chapter selection of the belt under the course of machine design 1. The learning outcome of this session is student will able to select the V belt from manufacturing catalog. So, this is a figure of the V belt in which this is the pulley in which the belt is mounted. This is a V belt. Generally, the angle of the V belt is 40 degree. So it utilizes the force of friction between the inclined side of the belt and the pulley. So there will be the definitely friction will get occurs between this pulley and the belt because of that friction the transmission of the power is going to occur. They are preferred when the distance is comparatively shorter. If the distance is more at that times we are preferring the flat belt drive. If the distance is smaller then we can prefer this belt. The several V belt can also be used together if power transmission is more. So if the power transmission capacity is more at that times we can use multiple V belt for example electric motor. So in the electric motor the distance is very smaller. So we can use the V belt in this case. So now we will see the design procedure for V belt drive. Step one determine the correction factor according to service from table. So the manufacturing table they had given us in the manufacturing data book. So from that tables we have to find out the correction factor. So from this tables we have to find out the value of F A. So in this table they had given us the type of service. So in the first column they had given us the type of service. So according to that we have to select. So if the light duty under the light duty if the type of the machine is agiator blower exhaust fan or the centrifugal pump compressor at that times we have to prefer this column. So in this column the multiple operation hours they had given us if the machine is going to work for the 15 hours per day we can prefer this column. So like this according to the type of service and the machines also we have to check out the hours per day we have to select the proper correction factor that is indicated by the letter F A. So step number two calculate the design power. So we have to find out the design power by using the equation P D is equal to P into F A where F A is service factor. So step number three we have to determine the cross section of the belt based on the design power and higher speed of the shaft in rpm from the following table. So you can think about this what are the types of V belt. So you can pause this video and think about this. So there are generally 5 types of the V belts are available A, B, C, D, E as also the Z type of the V belt is also available. So that based on the cross section of the belt. So from this manufacturing table we can find out the cross section of the belt. So in this table the A cross section belt is available B, C, D and E. Now there is a task to we have to find out the appropriate type of the cross section belt. So from this table if suppose the smaller pulley is rotated by 1000 rpm right if the smaller pulley is rotated by the 1000 rpm and if the power is 10 kilowatt at that time we have to prefer the appropriate cross section of the belt. So if suppose the 10 kilowatt power is that the horizontal line indicating the power and the vertical axis is indicating the speed of the faster pulley. So speed of the faster pulley is 1000 rpm so we can project the line and the 10 kilowatt power so we have to select the B type cross section of the belt. So like this depending upon the speed as well as the power we have to select the appropriate cross section of the belt. So the cross section of the belt if you have selected then we have to find out the this W, W stands for the nominal top width WP is nothing but the pitch width and T is nothing but the nominal height of the V belt. So if you have selected the B belt cross section of the B belt so at that time the pitch width is 14 mm, the nominal top width is 17 mm, the nominal height is 11 mm and for this kind of the B section belt we have to prefer the recommended minimum pitch diameter of the pulley is 200 mm. So we have to select the minimum diameter of the pulley that is a smaller pulley we have to select as a 200 mm. Step number 4 calculate the diameter of the bigger pulley so this is a equation for finding the diameter of the bigger pulley that capital D we have to find out as we are knowing the value of the input speed and the output speed as well as we have calculated the recommended diameter of the smaller pulley we have to calculate the capital D value. As we are getting the value of the capital D we have to select the value of capital D from the standard data book then next the step number 5 calculate the pitch length of the belt so by using this equation we have to calculate pitch length L as we are knowing the value of the center distance capital D small d we have to calculate the pitch length of the belt so this equation is for the open belt drive. Finally we have to calculate the pitch length for the cross belt drive by using this equation then step number 6 select the standard pitch length so we have to select the standard pitch length LP. So by using this equation we have to calculate the pitch length and if suppose the pitch length is 2500 so we have to select these tables 2500 we have to we can check this it is available standard pitch length if suppose by that equation we are getting the value as 2400 at that times we have to select the 2500 as a standard pitch length of the belt. Then step number 7 find out the correct center distance C by considering the standard pitch length so we had changed the pitch length according to standard table so we have to put the value of the L that is the standard pitch length again we have to calculate the center distance so if the belt is open belt drive we have to use this equation if the belt is cross belt drive we have to use this equation. Then the step number 8 determine the correction factor for the belt pitch length FC from the manufacturing data so this is the manufacturing data we have to find out the value of FC so if the belt pitch length is 2500 we have to select as 1 FC is equal to 1 then step number 9 calculate the angle of contact for the smaller pulley so by using this equation alpha s is equal to 180 minus 2 sin inverse capital D minus small d divided by twice c we have to calculate the angle of contact of the smaller pulley it is also called as wrap angle. Step number 10 find the arc of contact factor FD from the manufacturing data so this is the manufacturing data we have to find out the value of FD if you are getting the value of alpha s so for that alpha s we have to calculate the correction factor FD then step number 11 find the power rating PR from the manufacturing data so if the a section belt is there we have to calculate the value of PR if suppose the diameter is 118 right if the diameter of the smaller pulley is 118 for the 1440 rpm so the value of PR is 2.07 as well as we have to check out the speed ratio that is the speed of the faster pulley to the speed of the smaller pulley so if it is 2 and over then we have to add this point 17 so we are getting the value PR is equal to 2.07 plus 0.17 so like this the multiple tables are there for the a section b section similarly for the c section d section and e section we have to find out the value of PR from this table. Step number 12 determine the number of the belt so by using this equations we have to find out the number of the belt as already we have calculated these values just put this value in this equation and you will get the number of the belt so like this the simple figures are taken so in this figure the number of the belts are the 3 if we are getting the value of the number of the belt as 3 we can select the belt like this if we are getting the number of the belt is equal to 2 we have to select the 2 belt then the last design solution will be as diameter of the pulley that already we have to find out diameter of the larger pulley belt specification so the belt specification for the v belts we have to give like this b 3 2 LP sorry b 3 2 0 0 LP v belt this b is a cross section belt this 3 2 0 0 is a pitch line for the v belt number of the belt required capital N center distance C so these are my reference thank you.