such as the PT brake assemblies we just described.
normal engagement can occur. The clutch is made up of
Consisting of two complete units, a shaft break
a friction pack and dental clutch assembly. The friction
assembly is mounted on each starboard first reduction
pack is needed to bring the GTM input shaft speed to
quill shaft. Once all permissive are met, the single
within 11 rpm of the first reduction pinion. Once the
purpose of this break is to stop MRG rotation.
speed permissives are met, air pressure is applied to the
dental clutch to complete engagement. When the dental
MAINTENANCE OF EQUIPMENT
clutch is engaged, all torque is transmitted from the
GTM input shaft to the MRG's first reduction pinion.
This clutch assembly also houses a friction-type PT
brake that serves two purposes. The primary purpose of
The maintenance of the clutch and brake assemblies
the PT brake is to stop and hold the PT stationary. If the
and associated equipment and components will
PT brake is used in conjunction with an engaged clutch,
normally be accomplished according to the PMS.
the PT brake also acts as a shaft brake. The
General cleaning, tests, and inspections will be your
forced-synchronization clutch is being phased out of
primary concern. Because of the good operational track
Navy service in favor of the SSS clutch.
record associated with the SSS clutches,
troubleshooting and repairs should be minimal. This is
the main reason the Navy is phasing out the
forced-synchronization type of clutch.
In the following paragraphs, we will discuss some
The SSS clutch system performs the same functions
general maintenance and repair practices associated
by transmitting engine torque through the input shaft to
with clutch and brake assemblies that you, the GSM,
the MRG first reduction pinion. It does not, however,
may be required to perform or supervise.
require any external controls to perform the engagement
sequence. For clutch engagement to occur, the SSS
clutch requires only that the input shaft speed be greater
than the speed of the first reduction pinion. The SSS
The cleaning of clutch and brake assemblies will
clutch is fully automatic, and by design, centrifugal
primarily be accomplished when the MRG is cleaned.
force causes the main sliding member to move and
Cleaning the clutch assembly will be limited to external
engage with the output assembly.
cleaning with attention to the areas around the
Depending on the ship class, the SSS clutch system
inspection and access cover plates and the clutch
uses two different types of PT brake assemblies. The
position indicating ports.
CC-47 class ships have a PT brake assembly similar to
The cleaning of externally mounted brake
those installed on the DD-963 class ships. It is an
assemblies will require a little more effort. To properly
internally housed friction clutch design that is mounted
and thoroughly clean any of the external brake
to, but operates independently of, the SSS clutch
assemblies, you must remove the guard screen. Once
assembly. The main difference between this brake and
you remove the screen, pay particular attention to
the one installed on the DD-963 class ships is that it
removing any dust accumulation on the brake and to the
cannot be used as a shaft brake. Because of the SSS
cleanliness of the disc. It is important for you to keep
clutch design, even if the brake is applied with the clutch
dust accumulation to a minimum. Once the dust mixes
engaged, the clutch will disengage once the PT input
with oil, it can be deposited on the brake disc or absorbed
speed drops below the speed of the first pinion.
into the pads. Excessive dust and/or oil accumulation
The other type of PT brake assembly is the one
can seriously degrade the brake's operation.
installed on the DDG-51 and FFG-7 class ships. This is
a single-disc caliper brake assembly that is externally
Tests and Inspections
mounted to each PT input shaft. These brakes are also
used in conjunction with the SSS type of clutch in which
Unless a casualty occurs to either the clutch or brake
their only purpose is to stop and hold the PT stationary
assemblies, all tests and inspections will be performed
according to the PMS. For all practical purposes, there
The last type of brake assembly we will discuss is
are no tests or inspections related to SSS clutch
the shaft brake assembly. Shaft brake assemblies are
assemblies, unless you are assigned to a CG-47 class
installed only on the FFG-7 class ships. The shaft break
ship. Remember, that particular type of SSS clutch has
assembly is also a single-disc caliper brake assembly,
an internal PT brake assembly. The ship's maintenance