shall be integral components of standard hoists or hoist/trolley units of
manufacturers regularly engaged in the design and manufacture of hoists or
hoist/trolley units for Class A, B or C cranes. Gear reducers shall be
designed, manufactured and rated in accordance with AGMA 6010, or AGMA 6009
(for trolley drives only), as applicable. Except for final reduction, the
gear reduction units shall be fully enclosed in oil-tight housing. Gearing
shall be designed to AGMA standards and shall operate in an oil bath.
Operation shall be smooth and quiet.
2.3.6.2
Open Gearing
All gears and pinions shall have adequate strength and durability for the
crane service class and manufactured to AGMA 2001 quality class 6 or better
precision per [AGMA 2009-B] [AGMA 2011-A] [AGMA 2000]. Open gears shall be
enclosed with safety guards provided with openings with covers for
inspection and access for grease lubrication.
2.3.7
Brakes
Brakes shall be of the shoe, disc, or conical type with thermal capacity
suitable for class and service specified in this section. Shoe, disc, and
conical brakes shall be spring-set and electrically-released by a
continuously rated direct acting magnet. Brakes shall be self-aligning and
provide for easy adjustment for torque setting and lining wear. Brake
lining material shall be asbestos free. Brake wheels shall be cast iron
conforming to ASTM A 159 or shall be the manufacturer's standard
high-strength ductile cast-iron, provided that the material exhibits wear
characteristics in the form of powdered wear particles and is resistant to
heat-checking. Disc brakes shall be totally enclosed and have multiple
discs with stationary releasing magnets. Brake torque shall be easily
adjustable over a 2:1 torque range.
2.3.7.1
Hoist Holding Brakes
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NOTE: If non-critical loads are handled, one hoist
holding brake with a torque rating of 150 percent of
motor full load torque should be specified. If
critical or hazardous loads are handled, two holding
brakes with a torque rating of 125 percent of motor
full load torque should be specified. Specify two
holding brakes for DC control systems.
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Each hoist shall be equipped with at least [1] [2] holding brakes. Holding
brake shall be disc, shoe, or conical design, applied to one of the
following: motor shaft or gear reducer shaft or rope drum. Braking system
shall be designed to have zero hook lowering motion when a raise motion is
initiated. Primary brake shall be a spring-set, electrically-released,
disc, shoe, or conical type brake. Brake shall have a minimum torque
rating of 150 percent of motor torque. Brake shall be capable of holding
the rated load with zero hook drift. Primary brake shall be automatically
set when controls are released or when power is interrupted. Provisions
shall be made to facilitate easy brake adjustment. Hoists shall be
furnished with mechanical-control braking or a power-control braking
system. Typical power means include dynamic lowering, eddy-current
braking, counter-torque, regenerative braking, variable frequency, and
adjustable or variable voltage.
SECTION 14630A
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