CHAPTER 4REDUCTION GEARS AND RELATEDEQUIPMENTThis chapter contains information on theoperation, care and maintenance of reductiongears and related equipment found on Navy ships.All EN1s and ENCs must be familiar with thedesign and construction details of naval reductiongears and related equipment. When more detailedinformation is needed, refer to the manufacturer’stechnical manual.REDUCTION GEARSThe main reduction gears are the largestand most expensive single units of machineryfound in the engineering department. When themain reduction gears are installed properly andare operated properly they give years of satisfac-tory service. However, when casualties occur tothe main reduction gears they put any ship outof operation or force it to operate at reducedspeed. Main reduction gear repairs are verycostly. Usually they must be accomplished by ashipyard.FACTORS AFFECTING GEAROPERATIONProper lubrication is essential for the efficientoperation of reduction gears. This includessupplying the proper amount of oil to the gearsand bearings, and keeping the oil clean and atthe proper temperature. All abnormal noises andvibrations must be investigated and correctiveaction must be taken immediately. Gears andbearings must be inspected in accordance with cur-rent instructions issued by NAVSEA, the typecommander, or other proper authority.Lubrication of Gears and BearingsThe correct quantity and quality of lubricatingoil must be available at all times in the main sump.This oil must be clean and it must be supplied tothe gears and bearings at the pressure specifiedby the manufacturer. In order to supply theproper quantity of oil, several conditions must bemet. The lubricating oil pump must deliver theproper discharge pressure, and all relief valves inthe lubricating system must be set to function attheir designed pressure. Too small a quantity ofoil will cause the bearing to run hot. On the otherhand if too much oil is delivered to the bearing,the excessive pressure will cause the oil to leak atthe seal rings, and may also cause the bearing tooverheat.Lubricating oil must reach the bearing at theproper temperature. If the oil is too cold, therewill be insufficient oil flow. If the oil supply istoo hot, some lubricating capacity is lost. Formost main reduction gears, the normaltemperature of oil leaving the lube oil coolershould be between 120°F and 130°F. For fullpower operation, the temperature of the oil leav-ing the bearings should be between 140°F and160°F. The maximum temperature rise of oilpassing through any gear or bearing, under anyoperating condition, should not exceed 50°F, andthe final temperature of the oil leaving the gearor bearing should not exceed 180°F. Temperaturerise and limit may be monitored by a thermometeror by a resistance temperature element installedwhere the oil is discharged from the bearings.Cleanliness of lubricating oil cannot beoverstressed. The oil must be free from suchimpurities as water, grit, metal, and dirt. Par-ticular care must be taken to remove metal flakes4-1
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