MAINTENANCE OF ELECTRIC HYDRAULIC ACTUATOR
GENERAL. The electric hydraulic governing
system controls the engine speed, either independently, in
parallel with other sets, or with commercial power.
Components of the system include the electronic
governor controller A106, and the hydraulic governor
actuator. The governor actuator is a proportional actuator
with a backup centrifugal governor. The actuator has a
transducer which directs oil pressure to actuate the fuel
control mechanism on the engine. The governor actuator
has two major sections, the electric governor section, and
the centrifugal governor section.
TEST. The following test is required after repair
or overhaul using a test stand.
Recommended Tools. Recommended tools are
listed in tables 2-1 and 12-1.
shown in figure 12-1, to hold speed adjustment screw.
Turn spring seat (56, figure 12-3) until the pilot
valve plunger for the actuator gently bottoms,
then back off two turns. Screw spring seat screw
(56) until actuator's power piston (152, figure
12-3) is all the way up, eliminating interference
from the actuator.
Check pointer alignment with maximum position
on dial plate by rotating terminal shaft in the
increase fuel direction until the power piston is all
the way up.
Table 12-1. Recommended Tools
Electric Hydraulic Actuator
Pilot Valve Wrench
Gauss Meter, Bell Model
Preliminary Steps. (See figures 12-1, 12-2, 12-3
Mount unit on test stand and
connect oil inlet, pump pressure and drain
connections (see figure 12-4). A minimum
oil pressure of 5 psi (0.07 kg/cm2) at a
temperature of 140 to 150°F (60 to 66°C) is
Drive the unit in the normal
clockwise direction of rotation.
Remove cover (13, figure 12-3)
and use adapter plate
This is important since the unit operates
below minimum position due to the linkage
arrangement between the actuator and
governor. The unit becomes unstable when
operated below minimum. This check of the
dial plate and pointer position insures that
the unit is operating in its correct range.
Surge the unit by setting speed
droop to zero and opening needle valve
(92). Zero speed droop is set when the pin
on bracket (32) is on a centerline