Maximum Speed Limit
The maximum speed limit defines the highest position the electronic throttle kit can take the actuator to, and therefore the highest speed that can be reached. The limit is established through the mechanical travel; it is chosen so as not to exceed the engine's rated speed and the speed the machine allows.
Three constraints are considered together when setting the limit:
- Engine: the rated speed must not be exceeded.
- Driven machine: the maximum input speed allowed by the pump, alternator or gearbox may be lower than the one the engine allows. For example mud pumps typically turn at 100-200 rpm and there is a gear or belt ratio in between; the limit is calculated according to that ratio.
- Mechanics: the actuator must stop before the throttle lever comes to rest on its own mechanical stop, otherwise the cable and the joint are strained.
On the GS740-3P this limit is taught with the blue wire trigger: the engine is brought to the desired top speed with the potentiometer, the blue wire is briefly touched to chassis, and after about 8 seconds the upper limit is stored in memory. The taught limit is not a protection; it does not prevent the speed running away in case of an engine fault or load rejection.
Context in which this term is used: Electronic speed and throttle control on a diesel engine