 Hello everyone. Today we will see the break. I am Sachin Rathore working as an assistant professor in Mechanical Engineering department from Walton Institute of Technology, Solemn. The learning outcome of this session is student will able to understand working of single block or shoe break. Generally the breaks is a device which is used to bring to rest a body which is in the motion or to hold the body in the state of rest or of uniform motion against a action of external force. Means if any kind of the rotating system is there, so we can stop by using the break. So break is a very important term in a mechanical engineering. The types of break, first one the hydraulic break. So hydraulic breaks we will observe in pump or hydrodynamic break and fluid agitator. So generally the hydraulic energy is used to stop the rotating system. So for that case we can call hydraulic break. Second type is electric break. So in that we will observe the examples of generators and AD current break. So electric energy we are using for stopping the rotating system. And the third one is mechanical break. So the mechanical breaks in which the mechanical energy we are using for stopping the rotating system. So generally if we can take the consideration of the any systems like how are the car break is a example of mechanical break. So in that the classification of mechanical breaks. So first one is single block or shoe break. Second one simple band break. Third one differential band break. Fourth one band and block break. And fifth one internal expanding break. So we will see all these five types one by one. So first one single block or shoe break. So this is a schematic diagram of single block or shoe break in which one lever is there which is pivoted at point O that is called as a fulcrum O. And on that lever the shoe or the block is mounted rigidly and our rotating wheel is there. That is also called as a drum. So when the drum will get rotated in clockwise or anti-clockwise direction at the times when we want to stop the rotating wheel where apply the force at one end of the lever by an amount of P in a downward direction then there is a friction wheel occurs in between block and the wheel and the wheel get stopped. So this is a working of single block or shoe break. So you can think about this what are the applications of shoe break. So generally the shoe breaks we will observe in case of or the bicycle break or we can see the train for stopping the train on that the train wheels we are using the shoe break. So this is a bicycle breaks. So such kind of the break is called as single block or shoe break. So we will see what is the working of this single block or shoe break. This is a rotating drum on which when we are applying the force of the shoe and this shoe is attached by using the lever. It is pivoted at point O it is also called as a lever end on which we are applying the force P in the downward direction. Suppose the length of the lever is L and the center of this wheel distance from fulcrum to the center of the wheel is A. This is a block which is rigidly fixed to this lever when we are applying the force P in the downward direction at one end of the lever then there is a friction awkward between this rotating wheel and this block. The angle of this blocks is 2 theta and R is radius of this wheel. This is a wheel or drum. This is a lever. So we will see how the forces are acting on this wheel. So if suppose the wheel is rotating in clockwise direction. So at that time the normal reactions from this block to the wheel is acting in a downward direction and the frictional force if it is rotated in the clockwise direction the frictional force will act like this. So this is our the normal reaction R and on the wheel and the frictional force f is equal to mu R and this is a free body diagram of wheel. So what are the friction will occurs that occurs on this block or the shoe because the material of the shoe or the block is softer than that of the wheel. So we will draw the free body diagram of block. This is our the block and here the lever is there. So on this block as on the wheel the normal reaction is acting vertically downward direction. So the normal reactions occurs on the block or the shoe it is acting in a upward direction and the frictional force is opposite of this frictional force it is acting in this direction that is the f is equal to mu Rn. So like this forces are acting on this block. So we have to calculate the value of Rn because what are the amount of the friction will occurs that will occurs on this block. So for designing purpose we should know how much amount of the friction will occurs. So for finding the value of Tb, Tb is nothing but the breaking torque. So the breaking torque is nothing but the frictional force f into radius of wheel and this frictional force f is equal to mu Rn into the R. Therefore Tb is equal to mu Rn into the radius of the wheel. So by using this equation we can easily calculate the value of breaking torque. So here the important term is Rn. So our task is to calculate the value of normal reaction Rn. So for calculating the normal reaction there are two cases. So first one your the drum will get rotated in the clock way direction or your drum will get rotated in the anti clock way direction. So respective through that our the direction of frictional force will acting in this direction or in this direction. So we will see that in the next session and the second thing is that the position of fulcrum. So in this case, the position of the fulcrum it may lie along the line of the friction. So this is the line of the friction of frictional force. So this is a frictional winding force. So if the drum will get rotates in the clock way direction the frictional force will acts in that direction and if your drum will get rotates in the anti clock the frictional force acts in this direction. So, the position of the fulcrum it may be the line along the line of the action of the frictional force at this position or the fulcrum O it is acting below the line of the action of the frictional force by an amount A or the position of the fulcrum is acting at this position that is above the distance from the line of the frictional force. So, these cases also we have to see in the next session. So, these are my references. Thank you.