3.13.4 Taper-type locking device (pulley and shaft). The head and tail pulleys shall be
provided with an inner hub which clamps to the shaft by moving axially along a taper in the
outer hub. The mechanical clamping shall be accomplished by the use of a screw member or
members providing for mounting and removal of the pulley.
3.13.5 Bearings. The head and tail shafts shall be mounted in self-alining, antifriction,
greasable-type bearings furnished with labyrinthtype grease and dust seals. Bearings shall
conform to FF-B-185. Mounting of bearings in a manner other than securing against shoulders
shall be subject to the approval of the contracting officer for the specific application.
3.13.6 Takeup adjustment. To provide belt tension, a takeup adjustment consisting of two
l-inch Acme thread arrangements (one per side) shall be provided at the tail pulley. The total
available belt take up shall be not less than 12 inches.
3.13.7 Belt carriers. The conveyor belt shall be carried between pulleys on troughing rolls,
troughing impact rolls, and return rolls conforming to the Conveyor Equipment Manufacturers
Association (CEMA) Standard No. 502.
188.8.131.52 Troughing rolls. The troughing roll assemblies shall be spaced not more than 3 feet
apart and shall start from the last impact roll and continue toward the head end of the upper run.
184.108.40.206 Impact rolls. The area under the receiving hopper, including the area under the jaw
crushing component, shall be provided with impact type troughing carrier rolls mounted at
intervals of not more than 1 foot measured center to center.
220.127.116.11 Return rolls. The return rolls and mountings shall be spaced not more than 6 feet
apart. One return roll shall be mounted on the upper run of the conveyor ahead of the tail pulley
and underneath or slightly to the rear of the back flashing on the receiving hopper. The
mounting may be modified to suit the installation. If the vertical centerline of the tail pulley is
within 6 inches of the back flashing on the hopper when 6 inches of belt takeup remains, the
return roll shall not be required.
3.13.8 Discharge conveyor belt. The discharge conveyor belt shall be not less than 30
inches in width, and constructed with not less than two plies of synthetic tensile fabric. The top
rubber cover shall be 1/8 inch thick and the bottom cover shall be 1/16 inch thick with a skim
coat between all plies.
18.104.22.168 Belt fasteners. The conveyor belt shall be provided with bolted-metal-plate
fasteners. If the conveyor belt is removed for shipment, it shall be provided with
bolted-metal-plate, hinge-type fasteners capable of disassembly and reassembly by removing and
replacing the hinge pin.