Proell governor is similar to Porter governor having central load at the sleeve. But, Proell governor differs from Porter Pivot governor in ‘size’ as well as ‘arrangement’ of fly-balls. Refer to Fig. 1.
Construction of Proell Governor
In Proell governor, comparatively small diameter fly-balls can be used for same height. In Proell governor, the fly-balls are mounted on the extension links of lower arms, whereas in case of Porter governor, the fly-balls are attached at the junctions of upper and lower arms. The lower arms with extension links in Proell Motion of sleeve governor act as ‘Bell crank lever’.
Fig. 1: Proell Governor
Under normal conditions, the extension links remain vertical; however, they change their positions with the variations in speed caused due to variations in load on the engine.
Working of Proell Governor
Proell governor works in the same manner as that of porter governor. An increase in speed of rotation (due to decrease in load) increases the radius of rotation of fly-balls and raises the sleeve, thus reducing the amount of working fluid (fuel) supplied to the engine. Conversely, decrease in speed of rotation (due to increase in load) decreases the radius of rotation of fly-balls and lowers the sleeve, thus increasing the amount of working fluid (fuel) supplied to the engine.
Application of Proell Governor
Proell governors are suitable for ‘medium speed range’ applications.