ball-and-socket type or heat treated ductile iron, self-aligning
type. All bearings, except those for bracket-supported driven
sprockets, shall be bolted to the tank walls. Bearings shall be
designed to allow minimum field variations without shimming.
Bracket supports, except on head shaft driven sprocket, will not
be allowed. Bearings above water shall be provided with flush
ball-check grease-lubrication fittings. Underwater bearings shall
be water lubricated with tops designed to prevent solids
accumulation. Underwater bearings shall have flush ball-check
grease-lubrication fittings for use during initial operation and
at times when the tank is dewatered. Take-up bearings shall be
provided on take-up shaft. Take-up bearings shall be
self-aligning, shall be arranged to slide between or to be
steadied by two cast-iron, mild steel or silicon bronze guides.
Take-up bearings shall have a minimum range of travel of 250 mm 10
inches and shall be positioned by a stainless steel or silicon
bronze threaded power bolt which shall be arranged for locking at
any position of the bearing. All bearings shall be rated for a
minimum of 5 years' continuous service condition.
(5) Collector Flights: Collector flights shall be made of Select
Heart California Redwood graded in accordance with RIS Grade Use.
Flights shall be 50 mm by 150 mm 2 inches by 6 inches and shall
extend the full width of the tank with 13 mm 1/2 inch clearance at
each end. Flights shall be spaced at approximately 2.75 to 3 m 9
to 10 foot intervals and shall operate at a linear speed between
10 to 15 mm per second 2 to 3 fpm.
Wearing shoes shall be provided on each flight to run on tee rails
on the tank bottom. Wearing shoes shall be fabricated of 10 mm
3/8 inch thick steel angles, case hardened to a minimum Brinell
hardness of 555. Wearing shoes shall be as wide as the flight
thickness and 25 mm one inch longer than the width of the bottom
rail. Flights shall be accurately drilled and notched at the
factory and shall be carefully grouped and fastened together for
shipment.
(6) Rails and Tracks: Two industrial type steel rails, minimum
weight of 7.26 kg per 900 mm 16 pounds per yard each, shall be
provided for each collector mechanism. All necessary splice bars,
rail clips, and appurtenances shall be included. Return tracks
shall be structural steel shapes having a minimum thickness of 10
mm 3/8 inch and shall be supported by steel cross members
supported from compartment walls.
2.9.3.2
Traveling Reciprocating Type Sludge Collector
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NOTE: Delete paragraph and subparagraphs thereto
when step aeration type is specified or extended
aeration type where eventual conversion to step
aeration is contemplated.
**************************************************************************
The equipment shall be traveling reciprocating type designed either to move
settled sludge to a sludge hopper or to continuously collect settled sludge
by means of an airlift pump integral with the sludge collector assembly.
The equipment shall include motor drive assembly, collector drive assembly,
and collector assembly.
SECTION 11375N
Page 48
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