Anti-gravity clamp

Anti-gravity clamps were devices capable of removing gravity from an attached object.

When the 200 shuttle bus was stranded on San Helios, the Tenth Doctor and Christina de Souza took some anti-gravity clamps from the Tritovore ship and attached them to the vehicle's wheels and its steering column. By using the gold in the Cup of Athelstan that Christina had nicked from a museum to conduct a charge, this activated the clamps and enabled the bus to be flown. (TV: Planet of the Dead)