Geared motor (direct drive):
L10-100,000 hours
Intermediate helical gearbox bearings:
L10- 17,000 hours
Geared motor (indirect drive):
L10- 17,000 hours
Speed reducer case shall be equipped with oil fill port, oil drain
line, and an oil level indicator pipe.
(4) Chain and Belt Drives: Drive transmission within and from
the drive assembly shall be by chain and/or belt. Chain and belt
drives incorporated in the drive assembly shall be designed with a
minimum factor of safety of 4 as applied to the ultimate breaking
or transmission strength of the chain or belt with respect to the
loads transmitted at normal continuous operating load. Chain and
sprockets or V-belt and pulleys connecting motor and speed reducer
shall be enclosed in a weather-proofed fabricated steel or
fiberglass guard. Chain connecting motor and speed reducer shall
be steel roller type. Sprockets shall be hardened ground alloy
steel or high-test cast-iron, having a minimum tensile strength of
276 MPa 40,000 psi cast in a chill, and shall have Brinell
hardness of not less than 360 with a chill depth of not less than
5 mm 3/16 inch. Sprocket teeth shall be accurately ground to fit
the chain. V-belts shall be rayon corded with heat and oil
resisting rubber covering. Motor position of V-belt drives shall
be adjustable to increase or decrease belt tension. The drive
sprocket shall be keyed on the output shaft of the speed reducer
and shall be bronze bushed with a grease-lubricated bronze bushing
and provided with shear pin overload protection. The drive chain
shall be of the steel roller type, shall weigh not less than 1.36
kg per 300 mm 3.0 pounds per foot, and shall have an average
ultimate tensile strength of 110 MPa 16,000 pounds. The drive
chain shall have a minimum pitch of 65 mm 2.6 inches. A drive
chain tightener shall be provided to adjust and tighten the chain.
c.
Collector Drive Assembly: Collector drive assembly includes
collector drive chain, sprockets, rails or tracks, and supporting
structure. Collector mounting to drive assembly shall be provided
with counterweight or similar device to counteract leverage
exerted by the collector assembly and permit all surfaces to be
scraped uniformly.
(1) Collector Drive Chain: Collector chains shall have an
ultimate strength of not less than 96.5 MPa 14,000 pounds each.
Chain links shall be of corrosion resisting malleable iron having
an average tensile strength of not less than 517 MPa 75,000 psi
and a Brinell hardness of 170 to 190. The drive chain shall
extend the full length of the run. Means shall be provided for
continuous lubrication of the chain. Chain drive shall be covered
by a metal guard of No. 15 zinc-coated steel. Coupling pins shall
be not less than 13 mm 1/2 inch in diameter heat-treated high
carbon steel. All other pins shall be stainless steel. Means for
chain adjustment shall be provided.
(2) Sprockets: Sprockets shall be high-test cast-iron, having a
minimum tensile strength of 138 MPa 20,000 psi cast in a chill and
shall have a Brinell hardness of not less than 360 with a chill
depth of at least 5 mm 3/16 inch. Sprockets shall be stress
relieved before machining. Sprocket teeth shall be accurately
SECTION 11375N
Page 51
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