type mounted directly on the conveyor shaft. Provide tie rods, when
required, to prevent reduction gear rotation and for adjusting belt tension.
2.11.3.8
Service Platforms
Provide service platform conforming to OSHA regulations as indicated to
properly maintain and service conveyor drive unit.
2.11.4
Bucket Elevator
Provide a dusttight bucket elevator centrifugal discharge type, having
approximately [_____] meter foot [_____] mm inch sprocket centers, vertical
chain and bucket, operating at a speed not to exceed [_____] meters per
second (m/s) feet per minute (fpm), and having a capacity of not less than
[_____] Mg per hour of 640 kg per cubic meter tons per hour of 40 pounds
per cubic foot ash. Provide bucket elevator complete with continuous chain
and attached buckets, sprockets, gears, shafts, bearings, casing, top hood,
discharge spout, bottom boot, access doors, electric motor, reduction gear,
service platform, and accessories.
2.11.4.1
Head and Foot Shafts
Head and foot shafts shall be not less than [_____] and [_____] mm inches
in diameter, respectively. Construct shafts of cold rolled steel and mount
in antifriction roller bearings with forced lubricating type fittings.
Mount foot shaft in fixed pillow blocks. Head shaft shall have screw-type
takeups with not less than [_____] mm inches adjustment.
2.11.4.2
Terminal Sprockets
Cast iron with chilled rims. Head sprocket shall be not less than [_____]
mm inches in diameter and foot sprocket not less than [_____] mm inches in
diameter.
2.11.4.3
Buckets and Chain
Construct buckets of malleable iron not less than 200 mm long, 127 mm wide,
140 mm deep 8 inches long, 5 inches wide, and 12 inches deep.
Buckets
shall be mounted by not less than four bolt attachments to a single strand
of steel bushed chain having an ultimate strength of not less than 178 kN
40,000 pounds and pitch of 100 mm 4 inches. Bucket spacing shall be not
greater than 406 mm 16 inches.
2.11.4.4
Backstop
Differential band brake type to prevent reversal of chain and buckets in
case of power failure.
2.11.4.5
Casing
Elevator casing shall be not less than 298 by 991 mm 11 3/4 by 39 inches
inside and constructed of not less than 5 mm 3/16 inch thick commercial hot
rolled mild steel plate with 50 by 50 by 6 mm 2 by 2 by 1/4 inch corner
angles for full height of elevator casing. Fabricate casing in standard
sections from 250 to 300 meter high with 50 by 50 by 6 mm 10 to 12 feet
high with 2 by 2 by 1/4 inch angles at both flanges for each section.
Provide a hinged inspection door not less than 610 by 762 mm 24 by 30 inches
in the section immediately above the boot section and at other indicated
points. Casing and inspection doors shall be of dusttight construction
SECTION 15502N
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