There are two long bolts on the back of the pedestal at the height of these cogs. Wind these in as far as they will go before you split the column from the pedestal, these then provide a bit of support for the cogs. After you split off the column, you can usually wind them in a bit further. Just remember to wind them out after reattaching the column, as they cause quite a bit of friction otherwise.
Laying the pedestal on its back during transport will also help to keep the cogs in place. If they do come adrift, the legs of the pedestal have several panels that come off allowing access to the chain drives.
Ian is correct, the bolts are imperial (well they were on the 507 I moved).