The mechanical apparatus containing the interlocking logic, usually housed below the levers in a traditional signal tower. It consists of a complex grid of steel bars and locking dogs that physically block the movement of specific levers to prevent a dispatcher from setting conflicting routes or clearing unsafe signals.
Heard on the job
The signal maintainer is down in the locking room filing a dog on the locking frame to fix a binding lever.
Also heard as
- interlocking bed
- locking bed
Related terms
Locking room
The ground-floor space of an interlocking tower that houses the mechanical interlocking apparatus.
Lever frame
A mechanical assembly of large handles used to manually operate switches and signals.
Interlocking tower
A trackside building housing the levers and logic machines that control a local junction.