Chapter 4—REDUCTION GEARS AND RELATED EQUIPMENT
121.18
Figure 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 or
its access openings, plugs, piping, or attached fix-
tures shall be dismantled or removed without the
specific authorization of the ship’s engineer
officer.
Refer to the gear shown in figure 4-2 during
the following discussion. Assume that the after
bearing for the inboard pinion has been wiped
because of an obstructed oil passageway.
When making repairs to this unit, ensure the
propeller shaft is locked rigid and the lubricating
oil is pumped from the sump BEFORE the bear-
ing cap is disturbed. For the physical security of
main reduction gears refer to Naval Ship’s
Technical Manual chapter 9420 and current ships
instructions. After removing the bearing cap,
remove and inspect the upper half of the
bearing. Then, with the aid of a special jack, roll
out the lower half of the bearing. The function
of the jack is to relieve the weight from the lower
half of the bearing and to properly support the
rotating elements when the journal bearings are
removed.
The journal surface of the shaft and all oil
passages (nozzles) should be carefully inspected
and cleaned. The new bearing to be used to replace
the wiped one should also be cleaned and
inspected. Its crown thickness, as measured at the
factory, is stamped on the new bearing. The
measurements of the new bearing should be com-
pared with those of the original bearing and with
the specifications in the manufacturer’s
instructions.
After ensuring that the new bearing is well
oiled, the lower half of the bearing can be rolled
into place and the jack removed. Then the upper
half is placed in position. Be sure that the bear-
ing and its dowel are in the required position,
and in accordance with the manufacturer’s
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