Hobart 9OC24S Operation Manual page 46

OPERATION, MAINTENANCE, AND OVERHAUL MAN UAL, TM-240A
SELF-PROPELLED GENERATOR SET, SPEC. NO. 5381A
NOTE: Other safety switches added by Hobart are connected in the fuel
shut-off valve circuit and are described under Hobart modifications.
(c) Engine overspeed protection
The engine is protected against overspeed by the electric-hydraulic governor
,system and by speed-limiting mechanism in the fuel pump.
(5) Engine-cooling fan
The engine fan is designed to blow air outward through the radiator; rather than
draw it in as a conventional fan does.
Refer to the engine Operation and Maintenance Manual, which is included with these in-
structions, for more engine details.
C. Hobart Installed Engine Equipment (See Fig. 3)
The engine is modified at Hobart Brothers by the addition of the following equipment:
(1) Electric-hydraulic governor
An electric-hydraulic governor kit is installed on the engine to replace a con-
ven tiona I, mechan ica I type. The electric-hydraulic governor system, for con-
trol of engine speed (and generator output frequency), was selected for this
application because it provides faster engine response to changes in load con-
ditions. This results in much closer frequency control.
The governor system consists of the following main components :
Electric control unit with potentiometer
Hydraulic actuator
Magnetic pickup
(a) Electric control unit
The electric control unit (19) is a compact assembly of solid state components
enclosed in a metal box. It regulates the power supply to a constant voltage
for the amplifier section, senses speed changes and the rate of speed change,
and provides a voltage signal to the hydraulic actuator. The control unit is
equipped with a potentiometer for adjusting engine governed speed.