[an oil slinger] [pumps]. The drive shall be provided with an oil
"dam", spring loaded lip seals or other means of positive
protection against lubricant leakage around the output shaft. An
oil level gauge or sight glass and drain fittings shall also be
provided. The thermal rating of the gear reducer shall exceed the
design load or proper cooling shall be provided.
b.
Lubricating pumps shall be removable for maintenance without
disassembly of the drive and/or removal of the motor. Either a
low pressure or low oil level switch shall be provided to shut off
the unit in the event of insufficient lubrication.
2.3.2.6
Power transmission from the motor to the gear reduction system shall be
supplied by [a flexible coupling, direct driven. The coupling shall be a
nonlubricant type, manufacturer's standard, and shall be selected to
provide a minimum service factor of 2.0] [sheaves and [V-belts] [chains].
To reduce the output speed, the sheaves shall be removable.] The assembly
shall be covered with a suitable guard and shall be protected from
splashing.
2.3.3
Mounting
The drive system shall be a base mounted type which is separately mounted
on a concrete pier or a shaft mounted type which is supported by the drive
side rotor bearing.
2.4
LOW SPEED SURFACE AERATORS
The low speed mechanical surface aerators shall be furnished and installed
as indicated. Each unit shall be complete and include an electric motor, a
gear reducer, shaft and impeller driven at a constant speed, and all
necessary fasteners, stabilizers, anchoring devices, and other mechanical
and structural appurtenances necessary for the mounting and operation of
the units. The aerators shall be designed for continuous operation.
2.4.1
Impeller Shaft
The shaft shall be constructed of [carbon steel] [_____] and shall be sized
to withstand all torque loads and bending moments produced by operation of
the system. The shaft and bearing assembly shall be designed to allow
operation below 80 percent of its natural frequency without the use of
stabilizing devices. The shaft shall be so constructed that its deflection
will not affect the alignment of the antifriction bearings or cause
misalignment of the gearing during the mixing/aeration operation. The
shaft supporting the impeller shall be removable from the drive assembly,
without disassembly of the gear box. Rolling, antifriction type bearings
on the impeller shaft shall have a minimum L-10 life of 100,000 hours in
accordance with ABMA 9 or ABMA 11. The entire weight of the shaft and
impeller shall be supported by a thrust bearing integral with the gear
reducer. A rigid coupling shall be used to connect the shaft and turbine
assembly to the output shaft of the reducer. Bearings on the shaft shall
be either grease or oil lubricated, and shall be positively sealed against
penetration of moisture, or leakage of lubricant down the shaft. Provisions
shall be included for checking the adequacy of lubrication.
SECTION 11391
Page 18
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