Docking clamp

A docking clamp connected the dome of a Dalek to their upper grating section at the back. By releasing their docking clamp, a Dalek could tilt their dome forward, exposing their mutant form. (TV: Resurrection of the Daleks) Likewise, a similar "catch" connected the grating section to the weapons platform. (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)

While operating a vacant Dalek casing within the Moroks' Space Museum, the First Doctor opened up the dome to peek his head out of the casing. (TV: The Space Museum)

Aboard a Prison Station, the Delta Dalek and Epsilon Dalek sent by the Supreme Dalek released their docking clamps, ostensibly so that Kiston could extract samples of Dalek tissue for Davros' research into the Movellan virus. In reality, the device used by Kiston, once administered to the mutant Daleks, conditioned them to obey Davros. (TV: Resurrection of the Daleks)