The PSG governor providers hydraulic powered travel in the increase-fuel direction only. A return spring is used to provide travel in the decrease-fuel direction. The standard PSG cover provides for a vertical return spring in the governor. Governor models are available with horizontal return springs, or the governor can be fitted with a customer supplied external return spring.
Spring-driven and oil-damped ballheads are available to filter out torsional vibrations. A special temperature-compensated needle valve can be supplied to compensate for temperature effect on stability.
Droop may be set in some governors with a permanent movement of an adjustment inside the cover. Other governors are equipped with externally adjustable droop. External adjustment is available on either side of the case. Droop is adjustable from 0 to about 7 percent in all governors.
Electric speed-adjusting motors or pneumatic speed-setting is available for certain remote speed-setting applications. In most cases the speed-setting shaft dose not extend from the case when other types of remote speed setting are used.