In the worst case, with a rather flimsy roof, it may be necessary to apply the force at two points, one at each side of the roof and in line with the roller mechanism. Each case is unique. With some roofs and shutters, a rather complex system of pulleys and cables is necessary to insure smooth movement of the parts. For example, both Ash and Home domes have elegantly designed mechanisms. This brings us to the mechanisms for rotating domes and how domes must be stabilized with rollers to insure that they move smoothly.
Domes are almost always on rollers.
Rather appropriate since Yerkes was a railroad transportation mogul. In the case of non flanged rollers, it is clear that the dome would skitter right off of the rollers if it were not restrained by lateral rollers. The forces used to rotate the dome are applied in various ways, but all tend to push the dome off the rollers. In the case described above, the force is applied to one edge of the dome and would pull the dome right off but for the lateral rollers that keep it centered. Thus, the placement and quality of the lateral rollers should not be under estimated.