2.2
BEARINGS
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NOTE: The selection of thrust bearing type should
be left to the reducer manufacturer. The selection
of bearing type is based upon thrust load. For very
high thrust loads, a hydrodynamic fluid film thrust
bearing may be needed. If the designer has specific
experience which relates to which bearing type is
best for the application, one of the options for
thrust bearing type may be omitted.
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2.2.1
Thrust Bearings
Thrust bearings shall be either hydrodynamic fluid film type or
antifriction type. Antifriction thrust bearings shall be either tapered
roller or spherical roller type. The thrust bearing shall be sized for the
pump thrust plus the weight of the impeller and shaft. The thrust bearing
size and arrangement shall be coordinated with the pump supplier. The
bearings shall be able to sustain continuous operational load as well as
startup and shutdown loads. Hydrodynamic fluid film thrust bearings shall
use pivoted segmental shoes with the babbitted face surfaced as recommended
by the bearing manufacturer to maintain an optimum oil film.
2.2.2
Radial Bearings
Radial bearings for spiral bevel and parallel shaft reducers shall be
antifriction type. Radial bearings for epicyclic reducers shall be either
hydrodynamic fluid film type or antifriction type.
2.2.3
Hydrodynamic Fluid Film Bearings
The bearings shall be designed to have a minimum oil film thickness of 12.5
m 0.0005 inch under the most severe operating conditions. The bearing
loads shall not exceed 2400 kPa 350 psi for the maximum load. Where
hydrodynamic fluid film thrust bearings are used, suitable hydrostatic lift
provisions shall be made if required to prevent bearing damage during
startup. Thrust bearings shall be provided with either spring loaded or
embedded instrumentation to monitor operating temperatures.
2.2.4
Antifriction Bearings
Antifriction bearings shall be rated for an L-10 life of 100,000 hours at
the operating load of the reducer. Ball bearing load ratings shall conform
to ABMA 9. Roller bearing load ratings shall conform to ABMA 11.
2.3
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NOTE: Designer must delete inapplicable statements
which pertain to the gear types not used.
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[Epicyclic gearing shall be of the double helical design.] [Parallel shaft
gearing shall be of the helical design.] [Right angle gearing shall be of
the spiral bevel design.] Spiral bevel, helical, and double helical gears
shall be gas nitrided or carburized, hardened and ground. For epicyclic
SECTION 15005A
Page 11
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