Hydra-Mechanical Shutoff (HMSO)
1. Pull out the red emergency knob while
The HMSO will automatically stop the engine if there is
observing the air inlet shutoff valve.
an overspeed, low oil pressure or high coolant
temperature. The fuel rack and the air inlet shutoff will
activate when the engine overspeeds.
2. The air inlet shutoff knob must move to the
The fuel rack will reset automatically, but the air inlet
STOP position and shut off the air supply to the engine.
shutoff must be reset to the RUN position manually.
The engine must stop.
The HMSO uses lubrication oil from the engine. It has
3. Push in the red emergency knob to reset the
an oil pump that supplies pressure to the shutoff system.
There is a sump in the valve which must be refilled, if it
was drained, before starting the engine.
4. Move the air shutoff knob to the RUN position
to open the air inlet valve.
The HMSO can also be used as an emergency manual
Test the operation of the HMSO every 500 hours. Use