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  GEMCO Brake Systems Application Guide:
    Index
    Brake summary & key features
    Typical description &
       applications hydraulic brakes
    Typical description &
       applications electric brakes
    Selecting brake torque based
       on motor data
    Crane hoist braking torque
    Crane trolley braking torque
 		Selecting brake size based
   on load data
Overhauling load torque
Brake thermal capacity
Overhauling loads
Hydraulic brake selection for
   bridge cranes
Hydraulic brake torque ratings
   & thermal capacities
DC magnetic shoe brake torque
   ratings & thermal capacities
 
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 GEMCO Brake Systems Application Guide:
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Brake Systems Application Guide
 
BRAKE SELECTION FOR BRIDGE BRAKES
The following formulas apply for calculating linear loads such as bridge brake applications:

where:

KEL

=

Kinetic energy (ft-lb)

W

=

Weight (lb.)

V

=

Linear velocity (ft/sec)

G

=

Gravitational constant (32.2 ft/sec2)

R

=

Wheel radius (ft)

T

=

Stopping time

Td

=

Average dynamic torque (lb-ft)
 
Given in terms of tons, wheel diameter, gear ratios, etc., the specifications necessary to calculate crane bridge brakes include the following:
 
Empty crane weight—WE_____Tons
Full load crane weight—WL_____Tons
Max. bridge speed—FPM_____Ft/Min.
Stops per hour—N_____Number value
Track wheel diameter—DIA_____Inches
*Gear ratio brake shaft to track wheel—R_____(To 1)
Number of brakes—NB_____Number value
Acceleration rate—A_____Ft/Sec2.
Min. deceleration rate—dMN_____Ft/Sec2.
Max. deceleration rate—dMX_____Ft/Sec2.
Drive motor inertia—WKM2_____(Lb-Ft2)
 
* Drive motor RPM can be used to verify gear ratios, etc., for a maximum speed and track diameter.
 
In general, service bridge brakes should have sufficient thermal and torque range to stop the bridge within a distance of 10% of the full load speed with full load, or at a deceleration rate as specified by the original manufacturer.  
The kinetic energy and torque calculations can be stated in terms of crane specifications as follows:
 
Kinetic energy absorption rate, per brake per hour:
 

Minimum stopping torque (to stop empty crane at minimum deceleration rate):
 

Maximum stopping torque (to stop fully loaded crane at maximum deceleration rate):