Time rotor

The Time Rotor was a component in the central column of the TARDIS console. While the TARDIS was in flight, the rotor rose and fell, stopping when the TARDIS reached a destination. It was associated with the 'whooshing' noise heard when the TARDIS was in flight.

The aesthetic design of the Time Rotor, along with the rest of the TARDIS, occasionally changed throughout the Doctor's travels. The Time Rotor was considered to be connected to the lower engines; hence as the TARDIS moved the rotor moved accordingly. Its up-down motion may have been significant to the way the engines worked. As well as signifying the TARDIS' movement, the rotor was also known to malfunction or stop working when something went wrong e.g. the rotor stopped moving as the TARDIS engines stalled, rectified by the Doctor bumping the console (DW: Doctor Who).

The rotor, as it varied through designs, alternated between being a single column or a series of components that moved into each other from above and below. An example of the multiple columns would be in the ninth incarnation's TARDIS and the eighth incarnation's also. In the renovated TARDIS of the eleventh incarnation it was a single component, much like in the earlier versions.

The console in the TARDIS' secondary control room lacked a visible time rotor. (DW: The Masque of Mandragora)

Behind the scenes

 * It is interesting to note that in the non-canon Dalek movie spin-offs, Dr. Who and the Daleks and Daleks - Invasion Earth 2150 AD, the TARDIS lacked the time rotor or even a central console.