I have an overhead crane and we are having some issues with the gearboxes that drive the bridge. The total crane weight is 44250lbs and has a 4 ton capacity. The wheels are 13.5 inches in diameter and have a wheel load of 16500lbs. The gearbox is driven by a 2HP electric motor at 1750rpm. The gearbox itself is 30:1, the output speed is 233rpm and 2232in-lbs of torque. I added the weight of the crane and capacity to give me 52250lbs, and divide it by 4 for each of the wheels of the end truck I get 13062.5lbs. Using HP = n*T/5252 I can solve for T which should be the torque required to move the crane correct? I then have 5252*2HP/233rpm=T. This gives me a value of T=45.0015ft-lbs which is 540 in-lbs of torque. So our current gearbox has plenty of torque. Am I on the right path? I haven't done this in awhile. Thanks in advance.