I volunteer with an athletics group that has some large mats that they roll out for practice and I started thinking of a way for us old timers to roll them up at the end of practice. The mats are rolled up on a reel, that when empty is 14" in diameter, when full with the mats the diameter is 60 inches. I was thinking of adding a gearbox to the roll the reel. The mats are around 300lbs and around 150 feet long. We would only have to use the gearboxes to roll the mats back onto the reel, as it is really easy to unroll the mats by hand so I would have to find a clutch to engage to allow for freewheel option. The mats rest on a hardwood floor so friction should be pretty low. To find the maximum torque needed would be 300lbs x 30in=9000in-lbs correct? Thanks for checking my theory and answer and feel free to correct me if I am way off base.