Construction and Working of Internal Expanding Brake – Brakes and Dynamometers – Theory of Machine


Here we are going to see in this video the construction and working of an internal expanding brake as the name here we are having an internal expanding brake it is also called as drum brake if we look at the diagram here the parts of the brake are given we can see that at first here we are having a brake lining which is red in color next we have the brake drum this brake drum is the member which will be rotating and we have to stop the rotation of this member then we have a backing plate backing plate is like a support it acts as a support for the internal expanding brake next we have a cam this cam is the actual ting mechanism it means because of the cam the braking action takes place the starting of the braking action is provided with the help of cam then we have retracted spring now retracted spring is used that once the braking action has been taking place and then you have to bring the brakes into their proper position that is the initial position for that we are using the retractor spring so this was regarding the construction of internal expanding brake next if we see how it works at first when we are pressing the brake pedal means when we are driving a vehicle and in that if we are pressing the brake pedal then through linkages through mechanical linkages the brake pedal is connected to the cam the moment we press the brake pedal this cam will rotate and when this cam rotates it will be pressing or it will be pushing the brake shoes which we can see here the brake lining towards the brake drum it means the brake drum is rotating suppose I am assuming the direction as clockwise brake drum is rotating in clockwise direction and here at bottom if we are seeing these two they are called as anchor pins anchor pins are like fulcrum pins that is when the cam rotates this brake assembly will try to move about this fulcrum so here when the cam gets actuated when the cam is moving then about the fulcrum these brakes they would be moving outside and hence when they are moving outside the surface of the brake lining comes in contact with the inner surface of the brake drum and then the vehicle or you can say the brake drum stops so this was regarding the functioning of internal expanding brake instead of cam we can even have your cylinder and piston arrangement that is the brake fluid will enter it will push the piston on both the sides and then because of that Pistons the brake lining would be coming in contact with the brake drum so that is another method of actuate in the internal expanding brake one method is we can use cam here and the second method is we can use the piston and cylinder arrangement now such kind of brakes as they are called as drum brake the advantage of drum brake brake is that it is enclosed means here the construction which we are saying this construction will be visible to us once we open the brake drum otherwise it is completely protected next when the brake lining gets worn out in that case the braking for such kind of breaks it is very much we can say effective as compared to the other brakes so that is an advantage of internal expanding brake and if we consider where it is used it is mostly used in cars and we can say that in all four-wheeler vehicles the disadvantage of this break is that you’re the cooling of the break because as we know when breaking action takes place lot of heat is generated so since internal expanding break is enclosed we can say it is very much closed in that case what happens that the break does not get cooled effectively so that is a decibel advantage of internal expanding break and that is why to overcome that disadvantage we are going on to disc brake so with this we complete internal expanding brake

16 thoughts on “Construction and Working of Internal Expanding Brake – Brakes and Dynamometers – Theory of Machine

  1. You teach me more in 5 mins that what I get in an entire lecture of 1 hour. Thank you Sir. Keep up the good work. 😊 You explain very well.

    -Ruchi A.

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