Wheels on top or bottom?

Why do the wheels on observatories always go below the base ring and face up? I'm thinking of attaching them to the top of the ring on the dome, on a hinge, so they can be pushed down through the base ring to ride on a ring attached to the knee wall. When not engaged, the dome will be sitting flat on the base ring not on the wheels. This should help to keep the weather out while not in use, and make it easier to tie down during the rare toronado that passses by. that is attached to the dome.

Am I missing something? Confidence tend to be the feeling I get when I've overlooked something.

Thanks for all you help.

Dan

On the one we just built, as well as on most of the designs I've looked at, the wheels go on the bottom support ring and face up to the dome.

Then a skirt of some kind is attaced to the lower rim of the dome to keep the weather out.

I can visualize what you are proposing but I also think it might run afoul of the "keep it simple" rule, adding complication that can nip at you further down the road.

-Paul S. Walsh