 Hello students, myself Siddhasher B. Thurzapure, Associate Professor, Department of Mechanical Engineering, Walsh and Institute of Technology, Solapur. So, today we are going to deal with the topic Introduction to Turning Moment Diagram. The learning outcome of this session. At the end of this session, students will be able to interpret the turning moment diagram. The contents are definition of turning moment diagram, plotting turning moment diagram, areas or fields requiring consideration of turning moment diagram, cause of variation of output torque, terminologies in turning moment diagram and references. First of all, definition of turning moment diagram. Turning moment diagram, also known as crank effort diagram, is the graphical representation of the turning moment or crank effort for various angular positions of the crank. Now, the definition we can observe, it is nothing but it is graphical representation and that representation is between two parameters, one it is the turning moment or the crank effort or it is also called as torque and the second parameter is the angular position of the crank. So, between these two, what relation is there that will be represented on the graph and that graph it will be called as turning moment diagram. Plotting the turning moment diagram. So, it is plotted on the Cartesian coordinates and in the Cartesian coordinates, we are having that x axis and y axis and the x axis or the abscissa, we can take the crank angle and on the ordinate or y axis, we have to take the turning moment. Now, this is an example of a turning moment diagram. Now, in case of this one, we can observe that we are having the x axis here and the x axis it is representing the crank angle that is various angular positions of the crank and it is represented as theta. So, it will be in terms of radiance and we are having on the y axis the torque or the turning moment or crank effort it is. Now, in case of this diagram, you might observe that we are having this blue colored line. So, this blue colored curved line, it is indicating the torque or the turning moment at various positions of the crank it is. So, now, we can take some say crank angle it is say theta 1 and you can vertically upwards you will get the corresponding torque here. So, you can go for another angle crank angle it is theta 2 and you will get the corresponding torque here like this with the help of this graph what we can observe is there is variation of torque with reference to the crank angle that is the torque is not remaining constant. So, it is now in case of this one, there is no blue colored straight line which is horizontal which is representing the constant torque with reference to the crank angle that is there is variation of the torque with reference to the crank angle. Now, in case of this one, you can observe on the lower side it is done as one cycle. So, one cycle refers to the say the crank angle rotation. So, it is from 0 to we have taken here up to say it is theta 1 etcetera. So, here after this part we are if we are plotting the again the values of the torque against the crank angle we are going to have the repetition of the same curve it is that is the repetition of the torque and crank angle curve it is going to take place after this one. So, here up to this one we are going to call it as one cycle. This one cycle is representing nothing but it is crank angle rotation only, but it might vary with reference to the different types of the machines which we are using. So, it might be say 180 degree, it might be 360 degree or even it might be 720 degree etcetera. Areas or fields requiring the consideration of turning movement diagram. Turning movement diagram needs to be considered when there is variation of the output torque in a cycle that is the power source cannot provide the constant torque or the turning movement. Now, think of which are the power sources that cannot give the constant output torque throughout a cycle. You can think of the different power sources like the internal combustion engines are there like petrol engine, diesel engine etcetera. You can think of the external combustion engines having the reciprocating motion like say reciprocating steam engine. Then you can think of electric motor etcetera. So, out of this which is the power source which cannot provide the constant output torque throughout the cycle. So, the answer is these power sources are internal combustion engines like say petrol and diesel engines and also the external combustion engines like steam engines. So, in case of this one it is reciprocating steam engine and in both these cases you can see that we are having one power stroke at regular interval. Now, see the cause of variation of the output torque. The diagram it is now representing internal combustion engine. In case of this one on the top side we can see that we are having the spark plug or it is fuel injector is there. So, in case of internal combustion engine we are having different strokes as say it is initially suction stroke, then it is compression, then it is ignition and then it is lastly the exhaust stroke is there. So, in case of the ignition stroke we are going to have the ignition of the fuel inside this cylinder and then we are going to have the power stroke the piston it will be pushed vertically downward in the present case and we are going to have the crank rotation. So, this power stroke is not continuous. So, suction then compression then power stroke and then lastly we are coming to the exhaust stroke. So, the power is available only during the power stroke or the ignition stroke it is. So, that is the cause of variation of the output torque. We can think of the say reciprocating steam engine. In case of the reciprocating steam engine now here it is the cylinder is there. So, now the steam is generated outside and say the expansion of the steam it is taking place and the piston it will be moved towards the right hand side and then the rotation of the crank it is going to take place and based on whether it is double acting or single acting etcetera the backward motion of the piston it will be dependent. On this side also if the expansion of steam is taking place the piston will be pushed due to the pressure of the steam towards the left hand side it is. So, like this in this case also we are now having the intermittent say the power stroke will be there. So, not continuous one and even during the power stroke the say the speed it is going to vary because the pressure it is going to vary. Terminology is in turning movement diagram. In case of the turning movement diagram the present one it is say turning movement diagram for a 4 stroke cycle internal combustion engine and as told to you earlier you can see that here it is suction stroke compression stroke working stroke and the exhaust stroke is there and this one it is turning movement diagram is there. So, here the first term it is mean resisting torque. Now, suppose the IC engine it is connected to a vehicle and that vehicle is carrying a constant load from one place to another place that vehicle it has to move and that load is to be displaced from one place to another place. So, the corresponding to that constant load we are having this one as T mean it is say it is torque mean, mean resisting torque we are going to call this much it is constant requirement then energy or it is the work done. So, you can see that this say we are going to have these different say areas which are representing the energies and now we are having say the excess energy or the shortage of energy. Now, in case of this one the T mean line we observed above this one whatever portion of that turning movement diagram it is lying it is representing the excess energy. So, this triangle is there which is representing excess energy and on the lower side you can observe that sometimes there is say energy generation and if it is falling below 0. So, it is called as negative look energy will be consumed here. So, either say we are going to have the shortage or we are going to have the excess of the energy and whereas the requirement it is constant. You can see that the turning movement diagram for a single cylinder steam engine which is double acting. So, in case of the double acting steam engine so 0 to 180 will be one cycle and after this one you can see that the curve has been repeated from 182 to 360 degree. Then it is turning movement diagram for multi cylinder IC engine. So, in case of the crank is driven by number of cylinders like in case of the four wheelers or say the trucks and say buses etc. Number of cylinders we might have. So, cylinder number 1 corresponding to this one the turning movement diagram is there corresponding to cylinder number 2 and 3 also the turning movement diagram is there. So, in case of this one the resultant turning movement diagram is shown on the upper side and then the mean corresponding to the load which is going to be constant the mean torque line it has been shown here. These are the references which are used for this session. Thank you.