Motivator

Dalek motivators were a component of the Dalek casing which allowed them to move and ascend to hover position. (PROSE: Remembrance of the Daleks)

Behind the scenes
In NOTVALID: Inside a Skaro Saucer, motivators are depicted as humongous built-in "caterpillar tracks" which allow a Dalek flying saucer to move on land, crushing cities underfoot. They are occasionally used at the Dalek Commander's command.