PRINCIPLES OF NAVAL ENGINEERING 



OIL STRAINER 

 ^G AIR STRAINER 



R A NO REDUCING 



VALVE 



SA^SI 

 BOARD 



Figure 22-33.— Example of independent propulsion units. 



75.248X 



Tlie coupling illustrated has radial spring 

 packs as the flexible element. The power from 

 the engine is transmitted from the inner ring, 

 or spring holder, of the coupling, through a num- 

 ber of spring packs to the outer spring holder, 

 or driven member. A large driving disk con- 

 nects the outer spring holder to the flange on 

 the driven shaft. The pilot on the end of the 

 crankshaft fits into a bronze, bushed bearing on 

 the outer driving disk to center the driven shaft. 

 The ring gear of the jacking mechanism is 

 pressed onto the rim of the outer spring holder. 



The inner driving disk, through which the 

 camshaft gear train is driven, is fastened to the 

 outer spring holder. A splined ring gear is 

 bolted to the inner driving disk. This helical, 

 internal gear fits on the outer part of the crank- 

 shaft gear and forms an elastic drive, through 

 the crankshaft gear which rides on the crank- 

 shaft. The splined ring gear is split and the two 

 parts are bolted together with a spacer block at 

 each split-joint. 



The parts of the coupling shown in figure 

 22-35 are lubricated by oil flowing from the 



bearing bore of the crankshaft gear through the 

 pilot bearing. 



CLUTCHES, REVERSE GEARS, AND 

 REDUCTION GEARS 



Clutches may be used on direct-driven pro- 

 pulsion Navy engines to provide a means of 

 disconnecting the engine from the propeller 

 shaft. In small engines, clutches are usually 

 combined with reverse gears and used for 

 maneuvering the ship. In large engines, special 

 types of clutches are used to obtain special 

 coupling or control characteristics, and to pre- 

 vent torsional vibration. 



Reverse gears are used on marine engines 

 to reverse the direction of rotation of the pro- 

 peller shaft, when maneuvering the ship, without 

 changing the direction of rotation of the engine. 

 They are used principally on relatively small 

 engines. If a high-output engine has a reverse 

 gear, the gear is used for low-speed operation 

 only, and does not have full-load and full-speed 

 capacity. For maneuvering ships with large 



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