the casing covers must be opened for any reason other
entered the oil system. The condition must be resolved
than inspections, such as bearing removal, the work will
before it damages any other components on the MRG.
be performed by an outside activity. While the repairs
No Oil Flow Evident in an Individual Sight Flow
are being made, however, ship's company may be
Indicator. If there is no oil flow detected in any one of
allowed to assist in the repairs and will be required to
the sight flow indicators, this may or may not be a
provide the security watches.
serious problem. According to the EOCC, however, you
There are a few components that you may be
should always treat this symptom as if it were an
authorized to remove and repair. These components are
indication of a loss of LO pressure to the entire MRG.
the attached pump angle drive assemblies and the
Once the MRG is stopped, you can begin
clutch/brake assemblies, with we will discuss in the
troubleshooting by using the approved procedures. In
most cases, you will find the casualty was caused by one
of the previously mentioned problems we discussed in
the section concerning restricted or reduced oil flow.
CLUTCH AND BRAKE ASSEMBLIES
SHOCK MOUNTS AND SNUBBERS. A typical
Depending on the type of ship to which you will be
shipboard technician would have trouble identifying a
assigned, you will encounter either one or both of the
problem with the MRG shock mounts and snubbers
two types of clutch assemblies currently in use on gas
unless the problem were obvious. You will likely
turbine-powered ships. The first and most widely used
discover the more obvious problems, such as severe
clutch assembly is the syncro-self-shifting (SSS) type.
MRG vibration, loose, missing, or broken mounting
This type of clutch assembly is installed on all CG-47,
bolts, or large cracks in the shock mount or snubber
DDG-51, and FFG-7 class ships. The other is a
isolation material, during your operation or PMS
pneumatically operated, forced-synchronization type of
inspections. The repair work will be accomplished by a
clutch assembly, which is installed on DD-963 and
ship repair facility under the direct supervision of the
DDG-993 class ships.
Naval Sea Systems Command (NAVSEASYSCOM).
Along with the two types of clutch assemblies, there
PUMP ANGLE DRIVE ASSEMBLY.
are two types of PT brake assemblies installed on gas
Determining a problem in this area is not very difficult.
turbine-powered ships. One ship class has a separate
Symptoms such as excessive noise, difficulty in
shaft brake assembly, The type of brake assembly used
engaging or disengaging the drive, and a high failure rate
depends not only on the ship class but also on the type
of the attached pump flexible couplings are all good
of clutch assembly installed.
indications of a damaged drive assembly. If the problem
In this section, we will briefly discuss the normal
is caused by a failed bearing, the ship can usually make
operation and the maintenance related to both types of
the repairs. In most cases, however, the drive shaft will
clutch assemblies and all the brake assemblies. Because
be damaged and machine work will probably be
of its complexity, its elaborate control system, and the
required. If this is the case, assistance from a repair
large number of labors hours required for its
activity will be needed because your ship is not likely to
maintenance, the Navy is gradually phasing out the
have the experienced personnel or the required materials
forced-synchronization type of clutch. For this reason,
for this type of work.
we will focus our discussion mostly on the maintenance
TURNING GEAR. If the problem with the turning
practices associated with the SSS type of clutch.
gear is mechanical, then you would probably approach
troubleshooting the problem in much the same manner
as you would a problem with the pump angle drive
assembly. Just remember the turning gear is driven by
Both types of clutch assemblies perform the same
an electric motor and not by the MRG. If the problem is
function-they connect a GTM or the GTMs to the MRG
electrical, you will need to call upon a GSE to assist in
to drive the propulsion shaft. However, the method of
clutch engagement varies drastically between the SSS
Removal and Replacement of Components
Remember: Before you remove or replace any
components that require the MRG casing to be opened,
The forced-synchronization type of clutch requires
ship's service air and MRG LO to be available before
the engineer officer must be present. In most cases, if