Types of Governors
The type of
governor used on diesel engines is dependent upon the application required. The six basic
types of governors are:
centrifugal flyweight style that relies on a set of rotating flyweights and a control
spring; used since the inception of the diesel engine to control its speed.
servomechanical style that operates similar to the mechanical centrifugal flyweight but
uses engine oil under pressure to move the operating linkage.
governor that relies on the movement of a pilot valve plunger to control pressurized oil
flow to a power piston, which, in turn, moves the fuel control mechanism.
governor that is responsive to the air flow (vacuum) in the intake manifold of an engine.
A diaphragm within the governor housing is connected to the fuel control linkage that
changes its setting with increases or decreases in the vacuum.
governor uses a magnetic speed pickup sensor on an engine-driven component to monitor the
rpm of the engine. The sensor sends a voltage signal to an electronic control unit that
controls the current flow to a mechanical actuator connected to the fuel linkage.
governor uses magnetic speed sensor to monitor the rpm of the engine. The sensor
continuously feeds information back to the ECM (electronic control module). The ECM then
computes all the information sent from all other engine sensors, such as the throttle
position sensor, turbocharger-boost sensor, engine oil pressure and temperature sensor,
engine coolant sensor, and fuel temperature to limit engine speed.
used on heavy-duty truck applications and construction equipment, fall into one of two
governors, sometimes referred to as minimum/maximum models since they are intended to
control the idle and maximum speed settings of the engine. Normally there is no governor
control in the intermediate range, being regulated by the position of the throttle
or all range governors that are designed to control the speed of the engine regardless of
the throttle setting.
Other types of
governors used on diesel engines are as follows:
intended to maintain the engine at a single speed from no load to full load.
limiting, to limit the load applied to the engine at any given speed. Prevents overloading
the engine at whatever speed it may be running.
used for adjusting to the amount of load applied at the engine to suit the speed at which
it is set to run.
regulating, used on an engine driving a pump to maintain a constant inlet or outlet
pressure on the pump.
At this time
on heavy-duty truck and construction equipment applications, straight mechanically
designed units dominate the governor used on nonelectronic fuel injection systems.