Principles of naval engineering - Historic Naval Ships Association

PRINCIPLES OF NAVAL ENGINEERINGREDUCTION GEAR OIL COOLERREDUCTION GEAR OIL COOLERPORT REDUCTION GEAR STARBOARD REDUCTION GEARFigure 22-40.— Schematic diagram of reverse gear lubrication system.75.258When the coupling is assembled, the tworotors are placed facing each other to completethe doughnut (fig. 22-42). The rotors do not quitetouch each other, the clearance between thembeing 1/4 to 5/8 inch, depending on the size ofthe coupling. The curved radial passages of thetwo rotors are opposite each other, so that theouter passages combine to make a circularpassage except for the small gaps between therotors.In the hydraulic coupling assembly, shown infigure 22-42, the driving shaft is secured to theengine crankshaft and the driven shaft goes tothe reduction gear box. The oil inlet admits oildirectly to the rotor cavities, which becomecompletely filled. The rotor housing is boltedto the secondary rotor and has an oil-sealedjoint with the driving shaft. A ring valve,going entirely around the rotor housing, can beoperated by the ring valve mechanism to openor close a series of emptying holes (fig. 22-42)housing. When the ring valve is opened, the oilwill fly out from the rotor housing into thecoupling housing, draining the coupling completelyin two or three seconds. Even when thering valve is closed, some oil leaks out intothe coupling housing, and additional oil entersthrough the inlet. From the coupling housing,the oil is drawn by a pump to a cooler, thensent back to the coupling.Another coupling assembly used on severalNavy ships is the hydraulic couplingwithpistontypequick-dumping valves, .shown in figure 22-43. In this coupling, in which the operation is590