Ok, maybe I am being a little dense here, when conducting the experiments the cart does not actually move, the winch just applies a load as measured by the scale on the back of the cart? I am curious if there are differences in forces based on where the load is in relation to the winch? Would this method be more of a static load than vs. a dynamic load? Would that even make a difference on the measures you are recording? curious to see what you do next with this.....As I said previous, it was easier to put the winch load scale at the back of the cart inline with the anchor rather than build a sliding tray to mount the winch on. The rolling resistance is very low. Those are high dollar casters and the force to move it on the smooth concrete is sub 5 lbs if I had to guess. I can check it, but it is very low.