Overspeed Protection
A protective arrangement that stops the engine independently when the engine speed exceeds the safe limit. It typically trips 10–20 percent above rated speed and generally requires a manual reset. It is a chain that continuously measures speed and is independent of the throttle control; limiting the throttle lever position does not take the place of this function.
The protection logic is built on independence. Even if the throttle control itself fails, the protection must keep working; for that reason it has its own speed sensor and its own stopping path — a fuel shut-off solenoid or an air shut-off valve. Requiring a manual reset after it trips makes it compulsory that the event is recorded and its cause investigated.
A clear distinction is needed here. The GS740 and GS740-3P are not an overspeed protection. No such function is declared in the product documentation. The upper speed limit set in these kits limits only the mechanical position the actuator can go to; if the engine picks up speed for another reason (for example the load suddenly coming off, or a runaway), this limit has no effect whatsoever.
Therefore overspeed protection must be installed separately as part of the engine's own system and must not be skipped because a kit is present.
Context in which this term is used: Electronic speed and throttle control on diesel engines