not less than 320 BHN. Wheel sizing and flange-to-rail head clearances
shall be in accordance with CMAA 70 recommendations. Bridge travel wheels
shall have tapered treads.
2.3.6
Bridge and Trolley Brakes
**************************************************************************
NOTE: Select "100 percent" for outdoor crane, "50
percent" for indoor crane.
**************************************************************************
Provided crane with electro-mechanical bridge and trolley brakes conforming
to CMAA 70. Provide brakes with a minimum torque rating of [100] [50]
percent of the drive motor rated torque.
2.3.7
Bumpers
**************************************************************************
NOTE: Select "spring" bumpers for bridges on cranes
over 5 metric tons tons capacity or with a bridge
speed of over 250 mm/s 50 fpm; and for trolleys on
cranes over 10 metric tons tons capacity.
**************************************************************************
Provide bumpers on the bridge and trolley. Provide [spring] [elastomeric
or spring] type bumpers on the bridge. Provide [spring] [elastomeric or
spring] type bumpers on the trolley.
2.4
ELECTRICAL REQUIREMENTS
2.4.1
Motors
**************************************************************************
NOTE: Select two speed motors for bridge and
trolley drives if magnetic controls are specified in
paragraph entitled "Controls"; select single speed
motors if electronic controls are specified in
paragraph entitled "Controls."
**************************************************************************
NEMA MG 1. Provide [two] [single] speed AC squirrel cage induction type
motors for the bridge and trolley drives. Provide two speed, AC squirrel
cage induction type motor for the hoist. Motor insulation shall be Class
F. Provide totally enclosed non-ventilated (TENV) motor enclosures.
2.4.2
Controls
**************************************************************************
NOTE: Select one of the following options. The
first option provides magnetic controls for the
bridge, trolley, and hoist. The second option
provides electronic controls for the bridge and
trolley and magnetic controls for the hoist.
When the two-speed bridge and trolley motor is
specified, the slow speed will be 1/3 to 1/4 of
rated travel speed. Reduced voltage starting,
acceleration, and deceleration, serve to reduce the
acceleration rate that is normal for squirrel-cage
SECTION 14636N
Page 13
Previous Page
