Trapped Key Interlocking Systems

The locks follow a certain sequence which is not possible to by-pass. 
In the sequence above we want to unlock C. This will open the door to where a dangerous machine is.
To do this we need to start at A. 

1) Lock A switches off the machine. 
2) We can take out key B.
3) Key B is used to release key C and to open the door to the machine.
4) The person going into the machine brings Key C with him/her. 

The same locking sequence has to be followed backwards too. Taking out key A will start the machine. But this can only be done if the B & C keys have been placed back in the locks. 

In this way, no one can start a machine while someone is inside and working on it.
Learn more about the product in the videos below.

Lock sequence with several doors: 

Machine with run-down time and multiple doors: