shaft reducer or an epicyclic reducer. In some
cases, this choice may be left to the supplier to
allow them to make the most economical selection.
Both of these types of reducers will provide
reliable service. Epicyclic reducers become the
preferred choice for high wattage (horsepower)
vertical shaft prime movers (above approximately 750
kW (1,000 hp)). Again, single reduction reducers
should be used where feasible.
This section is intended to be used along with
UFGS-15131A VERTICAL PUMPS, AXIAL-FLOW AND
MIXED-FLOW IMPELLER-TYPE. The designer is
responsible for determining whether a speed reducer
is required or whether a direct drive vertical
induction motor can be used to drive the pump.
Guidance for making this decision is EM 1110-2-3105,
MECHANICAL AND ELECTRICAL DESIGN OF PUMPING
STATIONS. An additional section for the prime
mover, an electric motor or diesel engine, is also
normally added. The intention is for these
components to be purchased and installed by the
Construction Contractor. Purchase of the three
components in a single contract allows the supplier
to obtain the most optimum combination of components
thus reducing costs while not sacrificing
reliability. This also makes it feasible for the
Contractor to perform dynamic analysis as described
in UFGS-15131A and be solely responsible for
acquiring the necessary data to perform such
analysis. The dynamic analysis is important to
ensure the pump, reducer, and motor or engine
combination is free of detrimental vibration. If
the reducer and prime mover are purchased
separately, the designer is responsible to provide
additional plans and specifications covering reducer
instrumentation. Provisions for a pump, reducer,
and Provisions for a pump, reducer, and prime mover
base plate are described in UFGS-15131A. Pump and
reducer alignment is described in UFGS-15131A. The
"Buy American Act" which will be included in the
non-technical portion of the contract will preclude
the use of nondomestic reducers and appurtenances.
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The speed reducers shall be designed and manufactured by a firm that is
regularly engaged in the manufacture of speed reducers of the type utilized
for these installations. The reducer shall display the certified
manufacturer's AGMA insignia as evidence of conformance to these standards.
The nameplate shall bear the manufacturer's name, model designation,
serial number, unit rating, application factor, reduction ratio, and other
applicable information. The speed reducer shall be [single reduction
spiral bevel] [spiral bevel primary, helical secondary stage] [single
reduction parallel shaft] [double reduction parallel shaft] [epicyclic]
gear type equipped with thrust bearings to make the speed reducer suitable
for use with a vertical impeller pump. Where upthrust is possible during
pump startup or shutdown, the thrust bearing shall be designed to resist
this load. The speed reducer shall be able to withstand all of the
specified operating conditions without damage. A backstop shall be
SECTION 15005A
Page 8
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