Cylinder cam

The cam is the rotating part of the lock cylinder that, as the key turns, pushes the lock mechanism to throw or draw back the bolt. On a euro profile cylinder it is the tab that shows in the central part, between the two halves.

Its position matters: to take a cylinder out of the lock or put one in, the cam has to be tucked inside the profile. That is why, when changing it, you have to turn the key slightly until the cam lines up and the cylinder comes out.

If the key turns all the way round but the bolt does not move, the cam may be broken or not engaging in the case. It is a fault that can be fixed. More under lock installation and cylinder replacement.