TM 9-6115-604-34
NAVFAC P8-633-34
SECTION VI. ELECTRIC GOVERNOR SYSTEM
6-22. GENERAL. The electric governor system is an electrical sensing system that maintains precise control of engine
speed at any selected point, and provides rapid transient response to load changes. It is all electric and requires no
engine drive or hydraulic system. It is ruggedly built to resist vibration and physical damage. The governor system is
designed to provide steady state speed stability of less than plus or minus 0.25 percent, generally referred to as
isochronous regulation. Droop can be obtained with a simple jumper connection at the control panel terminal block. The
electric governor system consists of a magnetic pickup PUl (mounted in the engine flywheel housing), an actuator L101
(mounted on the fuel pump and electrically linked to the electric governor control unit), and a load sharing panel A104
(mounted inside cabinet B). The load sharing panel A104 is comprised of the electric governor control, a 50/60 Hz
module, and a precise load sharing module.
a.
Actuator.
(1)
The actuator Li 01 is an electromagnetic rotary solenoid valve mounted in the PT (Type G) VS-EFC fuel
pump. By regulating fuel pressure and hence fuel flow into the injectors, the actuator Li 01 determines
engine speed and horsepower.
(2)
The actuator Li 01 is controlled by the electric governor control unit which senses electrical signals
proportional to actual engine speed from a magnetic pickup PUl, mounted on the engine flywheel housing.
(3)
The electric governor control unit compares this feed back signal (engine speed and any speed variations
brought about by load changes) against predetermined speed control reference set points and provides
compensating current signals which turn the actuator shaft to either increase or decrease fuel pressure in
order to maintain the preselected engine speed regardless of load changes.
(4)
Anytime the load is increased, the engine slows down causing a decrease in frequency signal from the
magnetic pickup PUl. This signal change is picked up by the electric governor control unit which then
drives the actuator shaft to increase fuel pressure until the engine is brought back to the preselected
speed.
(5)
Refer to paragraph 6-9 for testing, removal, or replacement of the actuator.
b.
Magnetic Pickup PUl.
(1)
The magnetic pickup PUl is a magnetic device that is mounted in the flywheel housing. As the flywheel
gear teeth pass the pickup, an ac voltage is induced, one cycle for each tooth. The frequency input signal
from the magnetic pickup PUl may be as low as 0.5 volt rms or as high as 30 volts rms. A value of 1 volt
rms at cranking speed is adequate.
(2)
The magnetic pickup PUI is mounted through a threaded hole in the gear case of the flywheel bell housing.
The magnetic pickup PU 1 can be screwed in (with engine stopped) until the tip strikes the top of the gear
tooth, then backed out three-quarters of a turn and secured by the locknut.
c.
Battery Voltage Input. The input battery voltage is 24 V dc (do not connect to a battery charger). All circuits are
isolated from the case; therefore, no ground is required. The maximum input current for 24 volts is
approximately 3 amperes.
d.
Load Sharing Panel A104 (see Figure 6-30).
(1) The load sharing panel A104 consists of three components:
(a)
An electric governor control unit for engine speed control.
(b)
A precise load-sharing module for load sharing of two or more engines.
(c)
A 50/60 Hz module which permits the engine to operate generator G1 at 50 or 60 cycle operating
output. This module contains two frequency trim adjustments.
(2)
The load sharing panel A104 will provide accurate control at temperatures from -65 to 175F (-54 to 79C).
The power resistors on the load sharing module will develop some heat which must be dissipated.
(3) The three load sharing panel A104 components are prewired into the top row of the 30-position terminal
strip.
6-57
