 Hello, I am Sachin Rathod from Walsh and Instruct Technology, Solapur from Mechanical Engineering Department. Today we are seeing the topic toothed gear. So the learning outcome of this session is student will able to understand the terminology used in the gear. So introduction, gear is nothing but a toothed wheel that can works with other to alter the relation between the speed of driving mechanism and the speed of driven parts. Means just we are using the gear for transmission purpose from one shaft to another shaft. And the gear drive gives you the positive drive. Means if you use the belt drive, at that time slippage action will occurs. Due to that the efficiency will get decreased. So to avoid that we can use the gear drive. So terminology used in the gear. So what is the use of knowing the terminology of the gear? You have to think about this. So I will tell for designing any purpose we require to find out the dimension. So for finding the dimension we should know the different term used in the gear. So for that purpose we should know the terminology used in the gear. So in this figure we are getting areas term used in that gear. So we will see one by one. Okay, the first is a pitch point. The pitch point is a common point of contact between the two gears at which the pivot rolling action will occur. So these are the gear number one and gear number two. If we rotate these gears in this direction this gear will rotate in the direction. So if you rotate the clockwise direction we are getting the output as a anti-clockwise direction. So consider this one is a driver gear we are getting output at driven gear. So first thing is that pitch point. Pitch point is nothing but the common point of contact at which the pivot rolling action will occur. So that point should be acts along the two axis of gear. So this is a common point of contact. That is nothing but pitch point. Next one pitch circle. Pitch circle is nothing but the circle which is drawn due to the pivot rolling actions by two gears. So here the pivot rolling action we are getting. So from this point if you have drawn the circle which gives you the imaginary circle that will occurs due to the pivot rolling action is called as pitch circle. This circle is nothing but the pitch circle. Next one pitch circle diameter. The pitch circle diameter is nothing but the diameter of the pitch circle. It's nothing but this is pitch circle diameter that is getting the PCD. So this is the P circle diameter of the driver gear. This pitch circle diameter for the driven gear. Next one. We'll see the different terms. Addendum, deadendum, circular pitch, clearance, tooth space, tooth thickness, face, flank, topland and face width. So for that purpose the basic things we should know how to draw the gear. This is a tooth of the gear. This one is a thickness of the gear. So first one is a addendum. Addendum is nothing but it is a radial distance from pitch circle to the top of the teeth. So in this, this is a circle which is drawn from the bottom of the teeth. This is a circle which is drawn from the top of the teeth and this is nothing but the pitch circle where the pivot rolling action will occurs. So the addendum is nothing but it is a radial distance from top of the teeth to the pitch circle. Next deadendum, it is a radial distance from pitch circle to the bottom of the teeth. So this one is a addendum, this is a deadendum. And the circle which is drawn from the top of the teeth is nothing but addendum circle. This is addendum circle and the circle which is drawn from the bottom of the teeth is nothing but the deadendum circle. So this is deadendum circle. So next one is a circular pitch. Circular pitch is nothing but it is a distance measured along the circumference of the pitch circle from two adjacent teeth. Suppose this is a pitch circle that is measured along the pitch circle circumference along the two adjacent teeth. So this is called as a circular pitch. Circular pitch. Next one, clearance. Clearance is nothing but the distance in between the two mating gears from addendum circle to the deadendum circle. So if you observe in this diagram, the tooth thickness is up to this point and the tooth thickness is up to this. So this distance is called as a clearance. Next one, tooth space. Tooth space is nothing but it is a space in between the tooth along the circumference. So this is called as a tooth space. Next one, tooth thickness. Tooth thickness is nothing but it is a space between a tooth tooth along the circumference of the circular along the pitch circle. So this is a tooth space and this is a tooth thickness. Next one, face. Face is nothing but the surface above the pitch surface. So what is in the pitch surface? The surface at which the pure rolling action will occur. So we are knowing that this is nothing, this circle gives you the pitch circle. So this is nothing but the pitch surface. Pitch surface. So face is nothing but the surface above the pitch surface is called as face. So this shading portion is called as face. And flank, it is a portion below the pitch surface is called as a flank. So this portion is the flank. This surface is face. Next one, top land. The surface above the tooth is called as top land. Next one, face width. Face width is nothing but it is a axial distance of the tooth along the axis of that gear. This is called as face width. So such terminology are usually in the gear. These are the reference I have taken. Thank you.