Screw hanger bearings shall be rabitted-type, with cast iron hangers having
removable bearing caps held in place by a U-bolt. Design hangers to fit
inside the conveyor trough and equip bearing for grease lubrication with
grease fittings penetrating the dust cover to allow bearings to be greased
without removing dust cover. Hangers shall not be located at trough
joints, feed, or discharge openings. Locate hangers at not less than [3.66
meter12 foot intervals for screw diameters larger than 250 mm 10 inches]
[and] [3 meters10 foot intervals for screw diameters 250 mm 10 inches in
diameter and smaller].
2.9.11.4
Conveyor Screws and Couplings
Construct conveyor screws of helocoid-type flights and connect with cold
rolled steel couplings. Assemble conveyor screws so that at the hangers
there is 180 degrees rotation between the flight ends of each adjacent
screw section. Screw flight shall end over last discharge spout so bare
pipe extends across this area to prevent material carry-over.
2.9.11.5
Electric Motor
Totally enclosed, fan cooled, high torque, [_____] volt, three phase, 60
Hz, not less than [_____] kW hp as specified under paragraph entitled
"Motors and Drives" in this section. Install motor at discharge end of
conveyor. Motor shall be supported by a unit bracket attached to the screw
conveyor trough end plate and shall be connected to reduction gear through
a -belt drive. Reduction gear shall be shaft mounted, double reduction
type mounted directly on conveyor shaft. Provide tie rods, when required,
to prevent reduction gear rotation and for adjusting belt tension.
2.9.11.6
Service Platforms
Provide service platform conforming to OSHA regulations as indicated to
properly maintain and service conveyor drive unit.
2.9.12
Belt Conveyor
Inclined and approximately [_____] meter feet between pulley centers,
operated at a speed not to exceed [_____] m/s fpm, and have a capacity of
not less than [_____] Mg tons per hour of [_____] size coal. Provide belt
conveyor complete with continuous belt, shafts, pulleys, idlers, takeups,
belt cleaner, frame with conveyor cover and walkway, transfer chute,
hopper, emergency stop cord and switch, alignment switch, reduction gear,
electric motor, bin high level limit switch and alarm.
2.9.12.1
Head and Foot Shafts
Construct shafts of turned and polished cold rolled steel not less than
[_____] mm inches and [_____] mm inches in diameter, respectively. Mount
shafts in antifriction roller bearings with forced lubricating type
fittings. Mount head shaft in fixed pillow blocks. Foot shaft shall have
screw-type takeups with not less than [_____] mm inches adjustment.
2.9.12.2
Takeups
[Three pulley guided vertical counter weighted type] [Screw type] to
maintain proper belt tension. Shafts shall be as specified above and not
less than [_____] mm inches in diameter. Provide a safety device to
prevent free fall of take-up pulley. Takeups shall provide a minimum
adjustment of 1.5 percent of total belt length.
SECTION 15502N
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