(1) Drive Assembly Motor: Motor shall be constant speed, totally
enclosed, horizontal type, suitable for outdoor service, and
conforming to NEMA MG 1. The motor shall be of adequate wattage
horsepower to drive the equipment continuously at the maximum load
encountered under any operating condition without overloading or
exceeding the nameplate rating of the motor. Motor shall be
suitable for operation on [_____] volt, [_____] phase, [_____]
Hertz service. Motor shall be protected against overload, low
voltage, and unbalanced voltage. Motor shall be directly
connected to the speed reducer through a flexible coupling.
(2) Gearing: The main gear and worm gear assemblies shall be
enclosed in a cast iron or fabricated steel housing provided with
felt dust seals. Gear assemblies used in speed reducers or geared
motors shall conform to AGMA service classification II. Gears
used in the drive assembly shall conform to the applicable
requirements of the following standards.
Spur gearing and helical gearing: AGMA 908, AGMA 2001, AGMA 2004,
AGMA 6010, AGMA 6019, ASTM A 48M, ASTM A 48, ASTM A 536
Worm gearing:
ASTM A 536
The main internal or external spur gear shall be of high test
modular cast iron, heat treated alloy cast steel or heat treated
forged steel; pinion shall be of heat treated alloy steel or heat
treated forged steel. Worm gear shall be of cast bronze or
high-test cast iron; worm shall be hardened ground alloy steel or
high-test heat treated cast iron. The main internal or external
spur gear shall have an endurance and strength rating of 1,000,000
cycles.
(3) Bearings: All bearings incorporated within the drive
assembly shall be of the anti-friction type and conform to the
following minimum schedule of rated-life expectancy (L-10) based
on the ABMA SBRB Standards when operating at the normal continuous
torque rating of the collector:
Worm and wheel gearbox bearings:
L10-100,000 hours
Geared motor (direct drive):
L10-100,000 hours
Intermediate helical and spur gearbox bearings:
L10- 17,000 hours
Geared motor (in direct-drive):
L10- 17,000 hours
(4) Main Bearing Assembly: The main bearing assembly shall
include the arrangement of bearings on which the collector
assembly is mounted for support and alignment. The assembly shall
be designed for the radial and axial loads imposed by the drive
assembly and the sludge collector assembly. Bearings shall run in
an oil bath or shall be grease lubricated. The design of the main
bearing assembly shall permit the replacement of the balls or
rollers, or the steel liners, or the complete bearing unit.
Bearing raceway material shall have adequate strength to withstand
all radial and axial loads and shall have a minimum Brinell
hardness of 250. The assembly may incorporate an additional
submerged split-case, water-lubricated bottom guide bearing where
SECTION 11375N
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