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Mechanically controlled engines
Engine revs are regulated with a mechanical throttle
pedal, which transmits the pedal po sition mechanical-
ly via a throttle cable or rod to the injection pump (or
throttle body). The fuel demand on the injection pump
is adjusted via a mechanical injection pump lev er or
a mechanical throttle plate. To realize a speed limiting
system on a mechanically controlled engine, an elec-
tromechanical speed limiter is used to decou ple the
driver’s demand from the injection pump in order to
limit the maximum speed. In this application, the vehicle
must be equipped with a separate speed limiter sys-
tem.
Electronically controlled engines
Engine revs are regulated with a mechanical throttle
pedal which converts the mechanical pedal position
to an electrical signal, and transmits it via an electrical
wire to an electronic control unit. The control unit
regulates the fuel demand via electronic injection such
as electronic diesel control (EDC), a pump line nozzle
system (PLD) or common rail direct injection (CDI).
In this application, the speed limiter function could be
one of numerous functions managed by the engine’s
or vehicle’s electronic control unit.
Example of a mechanically controlled engine
Example of an electronically controlled engine with speed
limiter function in the engine or vehicle ECU
Mechanical injection pump
Mechanical linkage
Electrical throttle position
Electronic injection system
Technical conditions
Two different engine technologies used in vehicles require different speed limiter
device applications.