Interlocks are the blocking devices which ensure that the engine can be started or reversed only when certain conditions have been fulfilled.
When there is remote control of engines, it is essential to have interlocks.
Interlocks are defined as a way to prevent something from happening in a system.
A simple example of an interlock is pushing the brake pedal or clutch in your car before shifting it into drive or first gear. You need to press on the brake pedal to release the shifter into the drive position to prevent the car from lurching forward.
Interlocks reduces the possibility of engine damage and any hazards to the operating personnel.
Types of Interlocks in Main Engine:
- Â Turning gear Interlock: This device prevents the engine from being started if the Turning gear is engaged. It blocks the starting air from reaching the engine.
- Â Running Direction Interlock:Â This prevents the fuel from being supplied if the running direction of the engine does not match the Telegraph. An interlock also prevents starting of the engine if an attempt is made to start the engine before the reversing has been completed.
- Â Starting Air Distributor in the end position: This prevents starting from taking place if the shifting of the Distributor has not been completed.
- Critical Parameter Interlock: Key parameters such as Main Lube. oil pressure, Piston cooling pressure, Jacket water pressure, and important parameters must be above the required minimum.
-  Auxiliary Blower Interlock: The Auxiliary Blower is provided in the case of Constant pressure turbocharging. It should be in auto before engine can be started.
- Â Air Spring pressure Interlock: In case of the present generation of engines using Exhaust valves shut by Air Springs, the Air Spring pressure must always be maintained, else the exhaust valve may not close.
A smaller generator engine might have a tommy bar for manual turning interlock, the engine would not start if the Tommy bar is removed from its stoved position by a limit switch
