MAINTENANCE OF ENGINE ASSEMBLY
Section I. GENERAL
13-1. DESCRIPTION. This chapter contains detailed
instructions for maintenance of the engine assembly
which provides the mechanical power to drive the main
generator. The engine assembly consists of a 12-
cylinder, V-type, turbocharged, after cooled diesel engine.
13-2. REMOVAL OF ENGINE ASSEMBLY. Refer to
Chapter 2, Section IV, and remove the engine or
generator assembly, as required, for the replacement of
parts, repair, rebuilding, and overhaul of specific
components listed in this chapter.
Section II. SPEED SWITCH, TACHOMETER DRIVE AND ADAPTER, AND STARTER
13-3. SPEED SWITCH (Code "A"). To adjust and repair
the mechanical type speed switch, refer to figures 13-1
and 13-2 and proceed as follows:
The speed switch, driven by the
camshaft through a tachometer drive
assembly and an adapter, provides
sequenced control of circuits during engine
startup and protection against engine
overspeed during operation. Three sets of
contact elements, S9-1, SO-2, and S9-3,
contained in the speed switch, are set to
open, close, or transfer by centrifugal force
at certain engine speeds. The speed switch
drive gear is designed to drive the speed
switch at one-half engine speed.
At an engine speed of 580 to 620
rpm (accelerating) element S9-1 transfers
two sets of contacts, energizing the field
flash circuit and de-energizing the crank
relay to stop the starting motor.
When the engine reaches the
speed range of 1180 to 1220 rpm, element
S9-2 closes, energizing the
electrichydraulic governor which takes
control of engine speed.
Speed switch element S9-3
consists of two sets of contacts which are
set to transfer at an engine speed 2250
25rpm to shut down the engine and
prevent damage to the equipment.
Shutdown is achieved by de-energizing the
fuel shut-off valve, cutting off fuel to the
engine, and closing the air box solenoid.
Elements S9-1 and S9-2 reset at
100 rpm (decreasing) below actuation
speed. Element S9-3 is manually reset by a
pushbutton on the speed switch housing.
Speed Switch Removal. Refer to Operator/Crew
and Organizational Maintenance manual for
removal of the
Speed Switch Tests, Adjustment, Repair and
Installation (Mechanical Type Switch).
Connect a variable speed drive
device to the speed switch drive. The drive
device must have a tachometer in order to
determine the speed of the device in rpm's.
With an ohmmeter on the R1
scale, reading from the speed switch
connector, check for the contact conditions
of elements S9-1,