# Difficulty with band type brake

1. Apr 6, 2017

### torrgud

1. The problem statement, all variables and given/known data

What is the brake torque and the needed force to stop the drum.
Photo of problem: https://gyazo.com/5c814dc6791b29362cc2835dacf7005a

Data not on photo: Max pressure is 0.7MPa and friction coefficient is 0.2.

2. Relevant equations
T=(P1-P2)D/2
p=2P/bD
dP-fdN=0
dN=Pdθ
3. The attempt at a solution
The only thing I've been able to do is use p=2P/bD and rearange it to get F=8.68N
I am unsure of what dθ is supposed to be since the band lifts up on a portion of the drum.

Last edited by a moderator: Apr 6, 2017
2. Apr 6, 2017

### Dr.D

This looks like a textbook problem, and I suspect that the intent is that you use the given geometry, neglecting any lifting of the band.

3. Apr 7, 2017

### CWatters

There seems to be some information missing? Any braking force will eventually stop the drum if it's not being driven.

4. Apr 7, 2017

### torrgud

This was all the data I was given in the problem. There might be some eqations I forgot but the data is all there, at least what the teacher put.