The feeder shall be provided with four "
3.10.3 Ground mounting=
legs and frame supports for
mounting the feeder on the ground and
conveyor. When the feeder is ground mounted,
discharging into a portable
the height of the discharge
shall be not less than 48 inches.
3.11 Feed conveyor. The feed conveyor shall receive crushed material
from the reciprocating feeder. It shall deliver material into the
receiving hopper for the vibrating screen mounted on the screening unit.
The conveyor belt shall be 24 inches wide and shall be driven through
the head pulley by a 10-hp electric motor. The conveyor-belt shall
operate at a speed between 280 and 300 feet per minute.
3.11.1 Head pulley and drive. The head pulley shall be steel, not
less than 26 inches long and not less than 14 inches in diameter,
crowned and lagged, and shall be mounted on antifriction bearings.
184.108.40.206 Crown. The crown shall be approximately l/8-inch-per-
foot taper to the center of the pulley. The outside surface of' the
pulley shall be concentric with the shaft within a total-indicatxm
reading of 0.060 Inch, except that a total-indicator reading of O.090
inch is permissible in an area immediately adjacent to a longitudinal
220.127.116.11 Bearings. The mounting bearings shall be in accordance
with FF-B-185, class and type as applicable. Mounting Of the bearings
in a manner other than securing against a shoulder shall be subject
to the approval of the contracting officer for each specific applica-
tion. Taper-bore bearings are acceptable when affixed to the shaft
by an adapter incorporating a tapered sleeve and locking nut. Taper-
bore bearings need not be secured against shoulders.
18.104.22.168 Driving mechanism. The driving mechanism shall consist
of a reducing gear arrangement powered by a 10-hp electric motor
through a multiple V-belt drive. Gears shall conform to B6.6, class
2. Bearings shall be heavy duty, antifriction bearings and shall
conform to FF-B-171, FF-B-185, or FF-B-187. Bearings conforming to
FF-13-171 may be retained on the shaft by a bearing retainer plate
and shims between the retainer plate and housing to provide endwise
22.214.171.124. Hold-back device. An automatic hold-back device with an
overrunning clutch shall be furnished to prevent slippage or reversal
of flow when the motor stops.