Governor:

Diesel engine speed is controlled solely through the amount of fuel injected within the engine through the injectors. Since a diesel engine is not self-speed-limiting that's why it needs not only a means of changing engine speed (throttle control) but also a means of managing the desired speed. The governor provides the engine along with the feedback mechanism to modify speed as required and to manage a speed once reached.

A governor is necessary a speed-sensitive device, designed to manage a constant engine speed regardless of load variation. Because all governors used on diesel engines control engine speed by the regulation of the quantity of fuel delivered to the cylinders, those governors might be categorized as speed-regulating governors. As with the engines they there are several types and variations of governors. In this module, just the general mechanical-hydraulic kind governor will be reviewed.

The main function of the governor is determined through the application of the engine. In an engine which is needed to come up and run at only a single speed regardless of load, the governor is known as a constant-speed type governor. The governor is called a variable speed type governor if the engine is manually controlled or controlled by an outside device within engine speed being controlled over a range. The governor is a speed-limiting type if the engine governor is designed to keep the engine speed above a minimum and below a maximum. The last category of governor is the load limiting type. This category of governor limits fuel to ensure in which the engine is not loaded above a specified limit. Remember that several governors act to perform several of these functions concurrently.