The time anomaly relocation distributor was a feature of the TARDIS that took effect when a potentially dangerous time anomaly was detected. By default it moved the TARDIS forward "an hour or two". In this sense, it served the same purpose temporally as the HADS did spatially.
The name "time anomaly relocation distributor" was a bit of a mouthful, but unfortunately it couldn't be shortened to its obvious acronym, "TARDIS", as that would be apt to cause confusion. (AUDIO: Aquitaine)