Catch

What the First Doctor termed a "catch", similar to the docking clamp which connected the dome to the grating section, (TV: Resurrection of the Daleks) likewise connected the grating section to the weapons platform at the back of the Dalek casing. This catch could be released externally, and so tilted the top part of the Dalek casing forward, exposing their mutant form. (TV: The Daleks)

Within the Dalek City on Skaro, the First Doctor unlocked the catch connecting the neck and shoulder sections, allowing him and his companions to take out the Dalek mutant within so that Ian Chesterton could get in and operate the machine, posing as a Dalek. (TV: The Daleks)