help needed with brake calculation

[karmesh]

what is the force required to completely lock an 130mm drum brake(purely mechanical) assuming the vehicle is stationary and weighs about 160kg (not including rider).

 

[Tmoose]

I'm wondering what the "locking" will need to resist.
Prevent rolling downhill on a slight grade? Being nudged when a vehicle parks behind? Prevent being dragged off by a roving punk?

 

[gruntguru]

I think it is safe to say it needs to resist rotation with the tyre dragging on the road. So now we have 3 pieces of information - only need another 5 or so and we can have a shot at answering the OP's question.

je suis charlie

 

[tbuelna]

By definition, if the vehicle is stationary, the force required to "completely lock" the drum brake should be zero, right?

One nice characteristic of drum brakes is that they are self-energizing if the force is applied to the leading edge of the brake shoes. But this only helps if the drum brake is applied in one direction of rotation.

You can roughly calculate the braking torque needed from this 130mm drum brake simply from the static coefficient of friction at the contact interface, the normal force applied to the brake shoe, and the torque produced about the axle of the wheel being braked.

 

[Tmoose]

I think karmesh has left the building.

"After joining Eng-Tips Forums on February 14, 2015, I've logged in 5 times. My last login was on Wednesday, February 18, 2015."