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This manual provides description, operation, overhaul and replacement parts information for SG governors (Figure 1-1) and various optional auxiliary features. The SG governor is a hydraulic speed droop type governor used on small diesel, gas, or gasoline engines where isochronous (constant speed) control is not required. The design of the speed droop governor is such that the governor operates at a slower speed as engine load increases. It is through this characteristic that stability of the governed system is achieved, and division of load between paralleled units made possible.
SG governors are available with 10.8 or 21.7 inch-pounds (1.2 or 2.5 J) of work capacity over 36° of terminal shaft (output) travel.
If not supplied with an internal return spring, the 10.8 inch-pound governor requires an external return spring (not furnished by Woodward) that exerts a 20 pound-inch (2.3 Nm) torque on the terminal shaft in the closing direction. The 21.7 inch-pound governor requires a spring that exerts a 40 pound-inch (4.5 Nm) torque on the terminal shaft in the closing direction.
A new cover for the standard SG governor is a vertical return-spring type cover. This cover is used with or without a return spring, and also, with or without a Pittman PM (Permanent Magnet) speed-setting motor. For SG governors without a motor, the cover is furnished with a guide plug for the low-speed stop screw (see Figures 1-1 and 1-2).
The SG governor is usually arranged to operate at 2400 or 3600 rpm at normal rated engine speed, and will control down to approximately 25% of normal speed. Special configurations are available, however, to meet other speed requirements.
The governor uses engine oil or oil from a separate sump (not furnished by Woodward) as a control medium; it does not have an independent sump.
Product Specification 04048