I'm trying to solve a design problem involving the dimensioning of a gearmotor that drives a rack & pinion system to move a cart.
The cart weighs 600 kg and is supported by 4 V-shaped steel wheels such as those in the picture which are in contact with an L-shaped steel profile.
Now, the design speed for the cart is 0.5 m/s and the acceleration has a ramp of 0.5 m/s2.
I want to find the maximum tangential force on the pinion in order to choose the appropriate motor, and I know that it has two components:
- acceleration * mass
- mass * friction coefficient (600 * 9.81 * u)
Which is the appropriate value for the friction coefficient? I believe it should be the rolling friction between steel and steel (i.e. 0.005), but do I also need to take into account the radius of the wheel or something?
Thank you for any advice.