The precise movement is needed to align the center of gravity of the container to the center of the deck, or else the dollies may turn over when in motion. In addition, the containers or pallets on dollies are secured with built-in locks. Revolving platform - Some dollies have a revolving platform to facilitate rotating the ULDs to the correct orientation before transferring them onto a cargo conveyor belt or ULD/pallet lift leading to the aircraft bay.