One side of the brake drum gets more worn-out than the other

[marellasunny]

I have been trying to understand how the hand-brakes in my car function-and hence I read-up on brake drums and their functioning.

Reasoning that one brake shoe(i.e 1 friction shoe out of a total of 2) always gets worn more than the other: if its a leading-trailing shoe type

In common-usage, brake drums have an hydraulic force applied(see diagram, F_e) and depending on the direction of rotation of the drum,we can have a leading-shoe and a trailing-shoe.

I think the trailing-shoe gets more worn-out than the leading-shoe because there is a partial cancellation of the forces (as explained in the diagram) i.e a de-amplification of the input force.

Is it true in reality? Does one brake-shoe get more worn-out than the other as a theoretical force analysis suggests?

2.Also,can someone provide an insight into the term 'shoe-factor' that most brake engineers use to describe the self-amplification capacity of brakes? How does knowing this value help in racing?

 

[Navin A S]

Yes, it is true in reality. The leading shoe does tend to wear out more quickly than the trailing shoe because of the partial cancellation of the forces. This is due to the fact that the leading shoe is pushed into the drum by the rotating force of the drum, while the trailing shoe is pulled by the rotating force. Therefore, the leading shoe encounters more friction and therefore wears out faster than the trailing shoe.The 'shoe-factor' is a term that is used to describe the self-amplifying capacity of brakes. It is the ratio of the force applied on the brake pedal to the force exerted at the brake shoes. Knowing this value can be useful in racing, as it is important to understand how much force needs to be applied to the brakes in order to achieve the desired stopping power.