Forced-Synchronization ClutchThe forced-synchronization type of clutch requiresship’s service air and MRG LO availability beforenormal engagement can occur. The clutch is made upof a friction pack and dental clutch assembly. Thefriction pack is needed to bring the GTM input shaftspeed to within 11 rpm of the first reduction pinion.Once the speed permissive are met, air pressure isapplied to the dental clutch to complete engagement.When the dental clutch is engaged, all torque istransmitted from the GTM input shaft to the MRG's firstreduction pinion. This clutch assembly also houses afriction-type PT brake that serves two purposes. Theprimary purpose of the PT brake is to stop and hold thePT stationary. If the PT brake is used with an engagedclutch, the PT brake also acts as a shaft brake. Theforced-synchronization clutch is being phased out ofNavy service in favor of the SSS clutch.Synchro Self-Shifting ClutchLike the forced-synchronization clutch, the SSSclutch performs the same functions by transmittingengine torque through the input shaft to the MRG firstreduction pinion.It does not, however, require anyexternal controls to perform the engagement sequence.For clutch engagement to occur, the SSS clutch requiresonly that the input shaft speed be greater than the speedof the first reduction pinion. The SSS clutch is fullyautomatic. By design, centrifugal force causes the mainsliding member to move and engage with the outputassembly.Depending on the ship class, the SSS clutch systemuses two different types of PT brake assemblies. TheCG-47 and DD-963 class ships have a similar PT brakeassembly. The PT brake assembly is an internallyhoused friction clutch design that is mounted to, butoperates independently of, the SSS clutch assembly.There is one main difference between the CG-47 classships brake and the one installed on the DD-963 classships. The CG-47 brake cannot be used as a shaft brake.Because of the SSS clutch design, even if the brake isapplied with the clutch engaged, the clutch willdisengage once the PT input speed drops below thespeed of the first pinion.The other type of PT brake assembly is the oneinstalled on the DDG-51 and FFG-7 class ships. This isa single-disc caliper brake assembly that is externallymounted to each PT input shaft. These brakes are usedwith the SSS type of clutch in which their only purposeis to stop and hold the PT stationary when required.The last type of brake assembly we will discuss isthe shaft brake assembly. Shaft brake assemblies areinstalled only on FFG-7 class ships. The shaft brakeassembly is also a single-disc caliper brake assembly,such as the PT brake assembly we just describedConsisting of two complete units, a shaft brakeassembly is mounted on each starboard first reductionquill shaft. Once all permissive are met, the singlepurpose of thiS brake is to stop MRG rotation.MAINTENANCE OF EQUIPMENT ANDCOMPONENTSThe maintenance of the clutch and brake assembliesand associated equipment and components is normallydone according to the PMS. General cleaning, tests, andinspections will be your primary concern. Because ofthe good operational track record associated with theSSS clutches, troubleshooting and repairs should beminimal. This good operational record is the mainr e a s o nthe Navy isp h a s i n go u t t h eforced-synchronization type of clutch in favor of theSSS clutch.In the following paragraphs, we will discuss somegeneral maintenance and repair practices associatedwith clutch and brake assemblies. You, the GSsupervisor, must be familiar with these practices so youcan properly supervise maintenance and repairs.CleaningThe cleaning of the clutch and brake assemblies isdone primarily when the MRG is cleaned Cleaning theclutch assembly is limited to external cleaning. Payattention to the areas around the inspection and accesscover plates and the clutch position indicating ports.The cleaning of externally mounted brakeassemblies requires a little more effort. To properly andthoroughly clean any of the external brake assemblies,you must remove the guard screen. Once you removethe screen, pay particular attention to removing any dustaccumulation on the brake and to the cleanliness of thedisc. It is important that you keep dust accumulation toa minimum.Once dust mixes with oil, it can bedeposited on the brake disc or absorbed into the pads.Excessive dust and/or oil accumulation can seriouslydegrade the brake’s operation.Tests and InspectionsUnless a casualty occurs to either the clutch or brakeassemblies, all tests and inspections are performed3-9
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