2.6
MOTORS
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NOTE: Single speed motors are sufficient for slow
operating speeds. When two-speed motors are
specified, the slow speed will be 1/3 to 1/4 of the
rated speed. Squirrel cage motors normally have a
high acceleration/deceleration rate. Specifying
reduced voltage starting, acceleration, and
deceleration for the trolley (see article below
entitled "CONTROLS") will reduce this rate and
improve load spotting and handling ability.
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NEMA MG 1. Hoist [and trolley] motor[s] shall be [single] [two] speed AC
squirrel cage induction type. [Trolley motor shall be [single] [two] speed
AC squirrel cage induction type.] Motor insulation shall be Class B
minimum. Provide totally enclosed non-ventilated (TENV) motor enclosures.
Maximum motor speed shall not exceed 1800 RPM.
2.7
CONTROLS
Provide [single] [two] speed magnetic control for the hoist [and trolley].
[Provide [single] [two] speed magnetic controls for the trolley.] [Provide
reduced voltage starting, acceleration and deceleration for the trolley
drive.]
2.8
LIMIT SWITCHES
Provide upper and lower limit switches which de-energize the hoist motor.
2.9
BRAKES
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NOTE: Specify trolley brake for motor operated
trolley. Select "100 percent" for outdoor monorails
and "50 percent" for indoor monorails.
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Provide hoist with an electro-mechanical holding brake and a mechanical
load brake, each capable of holding 130 percent of the rated hoist
capacity. Hoist holding brake shall be capable of being released to test
the load brake. [Provide trolley with an electro-mechanical brake.
Provide trolley brake with a minimum torque rating of [100] [50] percent of
the drive motor rated torque. Trolley brake torque shall be adjustable
down to 85 percent of its torque rating.]
2.10
LOAD BLOCK AND HOOK
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NOTE: A minimum hook throat opening may be required
to accommodate special slings or other devices.
Check with user.
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Construct load blocks of steel. Provide forged steel, swivel type hook,
with hook nut keyed to hook shank by means of a setscrew installed in a
plane parallel to the longitudinal axis of the hook shank, or other similar
easily removable securing device. [Hook throat opening shall not be less
SECTION 14622N
Page 12
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