# Nip Roller Torque

1. Aug 20, 2013

### tomizzo

I'm wondering if someone could help me. I'm curious what the torque in each driven roller would be in the following picture.

Say for example I want the input tension(T1) to be 10 lbs and the output tension(T2) to be 20 pounds. Assume the radius for each driven nip is the same. Also assume there is a brake upstream somewhere. I am having difficulties in figuring out what the torque would be for each of the nips. I don't care about the speed of each nip but am only curious about the torque. I just don't understand how each nip isolates input and output tension. Any help?

2. Aug 21, 2013

### Baluncore

The torque on the roller is equal to the difference in tension on either side of a roller.
The tension force in the material is parallel to and equivalent to surface force on the roller, which can be interpreted as a torque of roller radius pounds.
If the output tension is zero,
then S2 = T2
and T2 = T1 + S1 etc
Make sure you get the signs correct.