basic clutch plate theory uniform wear

[warickwrx]

I have some theoretical questions about clutches that I would like some clarity on, I have answered them and would just like to check my understanding.

1. what is the relationship between frictional torque and axial load.

it is proportional ie linear as axial load increases so does frictional torque, but when does the clutch start to slip, is it when either of the propertied diminishes either axial load or coefficient of friction

2. If we use uniform wear and graph the two values of frictional torque vs axial load

Yes it would

I would think that yes under ideal conditions it would be a straight line as

3.how can we prove that friction torque is proportional to mean radius

As U = T/(W.R) where R is a constant if R where to increase U would decrease and visa versa

u= friction coefficient
T= frictional torque
W= axial load
R = (R1 + R2) /2 (uniform wear)

 

[desertfox]

try this site

http://www.freestudy.co.uk/dynamics/clutches.pdf

 

[tbuelna]

1. what is the relationship between frictional torque and axial load.....it is proportional ie linear as axial load increases so does frictional torque, but when does the clutch start to slip, is it when either of the propertied diminishes either axial load or coefficient of friction

The normal force applied to a conventional disc type friction clutch will result in a given level of torque transfer until the clutch begins to slip. Applying more normal force than that needed to prevent slipping will not improve the torque capacity of the friction clutch. The static coefficient of friction is greater than the sliding coefficient of friction at the clutch interface, so once breakaway occurs slipping can continue even if slightly less torque is applied. The coefficient of friction with most friction clutch materials is reduced as temperature increases. So the heat generated by slipping also tends to decrease the coefficient of friction at the slipping clutch interface. The one obvious exception are carbon-carbon clutch materials which experience an increase in sliding coefficient of friction as their temperature increases.