2.9.13.1
Body
Dusttight, of welded heavy steel plate construction with base angles not
less than 6 mm 1/4 inch thick. Top plate, bypass plate, and reducer
mounting plate shall be not less than 6 mm 1/4 inch thick, with other
plates of not less than 11 gage (3.04 mm0.1196 inch) steel plate. Provide
large, gasketed, dusttight doors with adjustable pre-set compression type
latches and forged steel hinges for inspection and maintenance purposes.
Door openings shall be sufficient to allow removal of feeder and hopper
without removal of screws or bolts.
2.9.13.2
Feeder
Feeder shall be a self-contained unit with an endless belt which shall be
capable of being removed from one end or side. Construct feeder of heavy
rigid steel frame with an 11 gage (3.04 mm0.1196 inch) stainless steel
plate to support the belt on the carrying run. Head and take-up shafts
shall be cold rolled steel carried on self-aligning ball bearings equipped
with dust seals and fitted for pressure lubrications. Bearings shall be
capable of being lubricated during scale operation. Take-up shaft shall
have screw-type take-up bearings and pulleys shall be crown faced steel for
proper belt tracking.
2.9.13.3
Feed Belt
Channel type and of endless construction without splice. Belt shall be not
less than 7.94 mm 5/16 inch thick of three ply heavy fabric core
construction with chemical and abrasion resistant rubber coating. Feeder
skirts and leveling plate shall be stainless steel and shall be arranged to
provide a continuous stream of constant width and depth coal on the feed
belt.
2.9.13.4
Electric Motor And Drive
Totally enclosed [_____] volt, [_____] phase, 60 Hz, with heavy duty
reduction gear not less than 0.56 kW 3/4 hp as specified under paragraph
entitled "Motors and Drives" in this section. Scale shall be capable of
bypassing coal without disconnection of the drive. Drive disconnection
shall not be required for feeder removal unless special provisions are made
for a quick and simple drive disconnection.
2.9.13.5
Coal Bypass
Provide a quick-operating coal bypass with an easily operable lever located
on the outside of scale body. Operating lever operation shall instantly
bypass coal around the feeder section and weighing mechanism without
release of belt tension to prevent entry of coal between belt and pulley or
support plates. Bypass construction shall not restrict inlet opening size
for normal scale operation.
2.9.13.6
Weighing Mechanism
Enclose in a dusttight compartment. Construct weighing mechanism of cold
rolled steel for minimum deflection, warp, and twist. Pivot points shall
be self-aligning with hardened double bearing surfaces. Weighing mechanism
shall be complete with weight lever, tare adjustment, and compensator,
[with design subject to approval by the Contracting Officer], and scale
shall be guaranteed to weigh coal accurately within 0.25 percent.
SECTION 15502N
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