A simple mechanical governor must overcome friction in the linkages and exert a control force. These forces act in different simple servo is however unstable because the pilot valve allows full oil to the servo or it drains the servo thus giving full fuel on or off conditions. Stability could be provided by making the value larger than the servo supply ports. This would however reintroduce a dead band. The solution is to provide feed back from the fuel linkage and this comes about with speed droop i.e. graph of % speed against engine load directions depending upon whether the load is increasing or decreasing. This in fact produces a dead band in which the governor will not exert any fuel control. By having the rotating weights only move a pilot valve which directs oil to or from a servo. The control force and friction forces are eliminated and hence the dead band is removed. The Speed control is carried out by varying the main spring tension acting on the flywheels. Feed b...