# Rolling resistance, stiction calculation for pipe roller

1. Apr 2, 2013

### aggie_mech

My ultimate goal is to spec a motor for a shop tool. It is a stand to rotate a glorified pipe. The pipes are quite large (up to 19,000lbs). The pipe will sit on four wheels. Two of the wheels are motorized. I have a good idea of the torque/hp needed to accelerate to the desired angular velocity based on the mass moment of inertia. I have ignored one thing so far though: rolling resistance or resistance due to static friction and wheel deformations.

I have searched on the internet and all I can find is one equation: F = Crr*N. F is the rolling resistance. Crr is the rolling resistance coefficient. N is the normal force. There is also a version where Crr is terms of a distance which is then divided by the radius of the wheel. This equation seems to primarily apply to a vehicle/car moving across the ground/floor.

How does this change in my case and are there any other applicable equations? Is there a way to calculate a more accurate Crr based on deformation and etc (the wheels might be supporting threads)? or is it a Crr guessing game?

Now if I know this rolling force, will be as if it is applied at the wheel surface? Will the torque required to overcome this force just be the radius of the wheel times the force?