PRINCIPLES OF NAVAL ENGINEERING 



OUTER 

 SPRING HOLDER 



INNER 

 SPRING HOLDER 



OIL SLINGER 



TAP BOLT 



PILOT BUSHING 



OUTER DRIVING 

 DISK 



TURNING RING 

 GEAR 



FITTED BOLT 



.INE RING 



?ANKSHAFT 



INNER SPRING HOLDER 

 ATTACHING BOLTS 



75.251X 



Figure 22-35.— Flexible coupling. 



Sintered blocks are made offinely powdered iron 

 or bronze particles, molded in forms to the de- 

 sired shape, under high temperature and pres- 

 sure. 



As far as engagement of the friction clutches 

 is concerned, the application of force-producing 

 friction can be obtained either by mechanically 

 jamming the friction surfaces together by some 

 toggle-action linkage, or through stiff springs 

 (coil, leaf, or flat-disk type). Air pressure is 

 also used to engage friction clutches. 



TWIN-DISK CLUTCH AND GEAR MECHA- 

 NISM.— One of the several types of transmis- 

 sions used by the Navy is the twin disk trans- 

 mission mechanism, shown in figure 22-30. Gray 

 Marine high-speed diesel engines are generally 

 equipped with a combination clutch, and reverse 

 and reduction gear unit— all contained in a single 

 housing, at the after end of the engine. A sec- 

 tional view of this mechanism is shown in figure 

 22-30. 



The clutch assembly of the twin disk trans- 

 mission mechanism is contained in the part of 



the housing nearest the engine. It is a dry-type, 

 twin-disk clutch with two driving disks. Each 

 disk is connected, through shafting, to a sepa- 

 rate reduction gear train in the after part of the 

 housing. One disk and reduction train is for 

 reverse rotation of the shaft and propeller, the 

 other disk and reduction train for forward ro- 

 tation. The forward and reverse gear trains 

 for Gray Marine engines are illustrated in 

 figure 22-36. In figures 22-30 and 22-36, it will 

 be observed that the gear trains are different in 

 the two illustrations; however, the operation of 

 the mechanisms shown is basically the same. 

 Since the gears for forward and reverse 

 rotation of the twin-disk clutch and gear mech- 

 anism remain in mesh at all times, there is no 

 shifting of gears. In shifting the mechanism, 

 only the floating plate, located between the for- 

 ward and reverse disks is shifted. The shifting 

 mechanism is a sliding sleeve, which does not 

 rotate, but has a loose sliding fit around the 

 hollow forward shaft. A throwout fork (yoke) 

 engages a pair of shifter blocks pinned on either 

 side of the sliding sleeve. 



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