Main engine interlocks

Interlocks are provided so 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.

This reduces the possibility of engine damage and any hazards to the operating personnel.

1.  Turning gear Interlock. This device prevents the engine from being started if the Turning gear is engaged.
2.  Running Direction Interlock. This prevents the fuel from being supplied if the running direction of the engine does not match the Telegraph.
3.  Starting Air Distributor in the end position. This prevents starting from taking place if the shifting of the Distributor has not been completed.
4. Main Lube. oil pressure, Piston cooling pressure, Jacket water pressure, and important parameters must be above the required minimum.
5.  Auxiliary Blower Interlock. The Auxiliary Blower is provided in the case of Constant pressure turbocharging.
6.  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