Hinge bolt

A hinge bolt is a steel pin that sticks out from the edge of the door, usually on the hinge side, and goes into a hole in the frame when the door closes. It is fixed: the key does not move it, it simply engages when the door leaf shuts.

Its job is to stop the door being taken out on the hinge side even if someone cuts or rips off the hinges. That is why security doors and armoured doors have them, and they can be added to other doors.

In Spanish the same word, bulón, is also used for the round bolts of multipoint locks. If a door starts to rub right where the bolts are, it is a sign that it is dropping and it is worth adjusting. More under lock installation and anti-jemmy hinges.