Overspeed Governor:
1. Speed of ME is primarily controlled by fuel lever setting.
2. Fuel lever controls fuel pump settings, which in turn control the amount of
fuel injected / working cycle, into cylinder.
3. Speed of engine would remains constant for any fuel lever setting, provided the load on engine did not change.
4. Overspeed Governor is fitted to ME, in order to keep engine speed within reasonable limits, in the events of load change, like in heavy weather, propeller shaft fractured or propeller is lost.
5. Governor is connected with fuel pumps or fuel pump suction valves.
6. When the speed of engine rises, governor reduces quantity of fuel injected, and when the speed returns to normal, it restores the fuel pumps to the setting given by fuel lever.
7. Overspeed governor operates within ME speed limits of 5 ~ 10% below and 10% above normal speed.
8. Hand adjusting gear is fitted, so that governor setting can be altered, while engine is running.
2. Fuel lever controls fuel pump settings, which in turn control the amount of
fuel injected / working cycle, into cylinder.
3. Speed of engine would remains constant for any fuel lever setting, provided the load on engine did not change.
4. Overspeed Governor is fitted to ME, in order to keep engine speed within reasonable limits, in the events of load change, like in heavy weather, propeller shaft fractured or propeller is lost.
5. Governor is connected with fuel pumps or fuel pump suction valves.
6. When the speed of engine rises, governor reduces quantity of fuel injected, and when the speed returns to normal, it restores the fuel pumps to the setting given by fuel lever.
7. Overspeed governor operates within ME speed limits of 5 ~ 10% below and 10% above normal speed.
8. Hand adjusting gear is fitted, so that governor setting can be altered, while engine is running.
Three types of Overspeed Governor:
1. Inertia Type. (Fitted on older slow speed engine)
2. Centrifugal mechanical Type [with spring-loaded sleeves and flyweights].
3. Mechanical hydraulic Type.
2. Centrifugal mechanical Type [with spring-loaded sleeves and flyweights].
3. Mechanical hydraulic Type.
Sensitivity: Ability to control the engine speed, within narrow limits.
Stability: Governor is stable, when there is only one radius of rotation of flywheel for
each speed, at which governor operates within the speed range.
Droop: Reduction or change in speed, which occurs from no-load to full load,
is ‘governor droop’.
Hunting: When engine load changed, governor tends to over-control and under-control,
and this causes fluctuation in rotational speed, which is referred to as ‘hunting’.
Stability: Governor is stable, when there is only one radius of rotation of flywheel for
each speed, at which governor operates within the speed range.
Droop: Reduction or change in speed, which occurs from no-load to full load,
is ‘governor droop’.
Hunting: When engine load changed, governor tends to over-control and under-control,
and this causes fluctuation in rotational speed, which is referred to as ‘hunting’.
Overspeed Trip:
1. Over-speed trip is fitted on engine, where governor may not be safe.
2. Its function is to shut-off fuel supply and stop the engine, when engine speed rises to dangerous level.
3. It protects the engine, when governor becomes inoperative, or shaft fractured or propeller is lost.
4. Mechanism has to be manually reset, before engine can be started again.
2. Its function is to shut-off fuel supply and stop the engine, when engine speed rises to dangerous level.
3. It protects the engine, when governor becomes inoperative, or shaft fractured or propeller is lost.
4. Mechanism has to be manually reset, before engine can be started again.
Trunk engine piston seizure:
Causes:
1. Blocked coolant supply to piston.
2. Overheating of the unit.
3. Exhaust valve damaged.
4. Rings damaged.
Causes:
1. Blocked coolant supply to piston.
2. Overheating of the unit.
3. Exhaust valve damaged.
4. Rings damaged.
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