Ok I figure you all may be able to help me with this one. I have a "Cooler", as in box that you put soft drinks, and other refreshments in), it’s in quotes due to the fact that it is huge and heavy (24x24x48). It is currently built on a set of 4 pneumatic wheels (4 inch wide x 9 in diamiter). At full weight it is 500lbs. trying to figure out what size motor I would need at what RPM, with what gear ratio, would produce the effect of 4 MPH. Also i was hoping for enough torque that a 15% Grade would only minimally reduce speed. please let me know if i am leaving anything out, or if this should have been in the mechanical heading. thank you for everyones/anyones assistance!!!