How can I determine if a single worm gear reducer will backdrive? The gearbox has a 15:1 ratio which has around 90 percent efficiency. The gearboxes output shaft also turns a pair of sprockets that creates a 3:1 ratio. This in turns 8" inch diameter steel wheel on a 28000lb trolley, that rides on steel rails on a level surface. The user wants to verify that if the trolley is not properly centered over it's load that it can center itself. Any help is greatly appreciate. Thanks to all of those who reply.