Chapter 4—REDUCTION GEARS AND RELATED EQUIPMENT121.18Figure 4-2.—Starboard gear unit with cover removed—view from aft and inboard.of the ship, the availability of Navy repair ac-tivities, and the operational schedule of the ship.CAUTION: No portion of the gear casing orits access openings, plugs, piping, or attached fix-tures shall be dismantled or removed without thespecific authorization of the ship’s engineerofficer.Refer to the gear shown in figure 4-2 duringthe following discussion. Assume that the afterbearing for the inboard pinion has been wipedbecause of an obstructed oil passageway.When making repairs to this unit, ensure thepropeller shaft is locked rigid and the lubricatingoil is pumped from the sump BEFORE the bear-ing cap is disturbed. For the physical security ofmain reduction gears refer to Naval Ship’sTechnical Manual chapter 9420 and current shipsinstructions. After removing the bearing cap,remove and inspect the upper half of thebearing. Then, with the aid of a special jack, rollout the lower half of the bearing. The functionof the jack is to relieve the weight from the lowerhalf of the bearing and to properly support therotating elements when the journal bearings areremoved.The journal surface of the shaft and all oilpassages (nozzles) should be carefully inspectedand cleaned. The new bearing to be used to replacethe wiped one should also be cleaned andinspected. Its crown thickness, as measured at thefactory, is stamped on the new bearing. Themeasurements of the new bearing should be com-pared with those of the original bearing and withthe specifications in the manufacturer’sinstructions.After ensuring that the new bearing is welloiled, the lower half of the bearing can be rolledinto place and the jack removed. Then the upperhalf is placed in position. Be sure that the bear-ing and its dowel are in the required position,and in accordance with the manufacturer’s4-5
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