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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
 
HYDRAULIC BRAKE TORQUE RATINGS AND THERMAL CAPACITIES
 
Using the table below, select the smallest brake size that will exceed KE and TMX calculations listed above. TMN calculations for air powered systems should be above "Minimum" torque limits below:
  

Brake Size

Max. KE per Brake per Hour (ft.-Ib)

Max. Dynamic Torque per Brake (Ib-ft.)**

Min. Dynamic Torque, All Air Powered Systems (lb-ft.)

Type H 1-Brake

Type H 2-Brake or
Type HM

All Air Powered

6 x 3

1.0 x 106

150

150

350

25

8 x 3

1.25 x 106

200

200

450

50

10 x 4

2.5 x 10

425

250

1000

75

14 x 6

5.0 x 106

600

350

1400

125

18 x 8

9.0 x 106

900

550

1800

175
 
** Based on 70 lb. pedal force, 8" max. pedal travel on Type H or HM manual systems.
 
Maximum stops per hour can be calculated using the following:

     where: (Max. KE per brake per hour) = Value for brake size as shown in table above.
 
The additional torque required to stop the drive rotor and the brake wheel inertia is normally insignificant and is ignored when the gear ratio (R) is less than about 10 x 1. If the gear ratio, and thus the drive rotor inertia is abnormally high, considerable torque may be needed just to stop the drive rotor.
 
To calculate the additional torque needed to stop the drive rotor and brake wheel inertia, proceed as follows:
 
1. Complete the previous calculations to establish the prelimary brake size.
 
BRAKE SIZE   BRAKE WHEEL INERTIA
6 x 3   .55 Lb-Ft.2
8 x 3   1.41 Lb-Ft.2
10 x 4   4.25 Lb-Ft.2
14 x 6   24.20 Lb-Ft.2
18 x 8   75.73 Lb-Ft.2
 
2. Record the following data from brake wheel inertia table above and additional data from previous calculations.

3. Calculate No Load Drive Torque, TNLD:

4. Calculate Full Load Drive Torque, TFLD:

 
5. Calculate Total Minimum and Maximum Torques:

6. Check to determine that TMxT is still within the torque limits of the brake size selected. If necessary, recalculate the problem based on alternate brake size and brakewheel inertia.
 
The chart below shows the dynamic torque values developed by manually operated brake systems. Maximum torques tabulated are developed at 70 lb. pedal force, the limit indicated by AISE and OSHA. Two maximum values are shown for 10 x 4, 14 x 6, and 18 x 8 brakes, as follows:

The chart below shows the dynamic torque ranges developed by air powered hydraulic systems. The maximum torques shown are developed by a 70 lb. force applied on the air treadle on Type A/H systems or applied on the pedal of the control cylinder on Type NHM-HRC systems. Air powered hydraulic systems include either a 1 x 5 or a 1 x 8 air hydraulic pressure cluster to apply the service brake. In addition, 10", 14", and 18" brakes include either a 7/8" diameter or a 1-1/8" diameter service brake actuator. Hence, 6" and 8" brakes have two possible maximum torque limits, while 10", 14", and 18" have four possible maximum torque limits.
 
The minimum torque limits shown are developed by light application of the treadle or pedal. Because of hysteresis and friction in the power system valves, it is not practical to consistently control less torque than the minimum calculated.

Static holding torque values tabulated below are those developed by the parking spring on the Type HM brakes. The brake must be correctly adjusted in order to get the holding torque tabulated.
  

Brake Size

6 x 3

8 x 3

10 x 4

14 x 6

18 x 8

Holding Torque, lb-ft.

35

50

450

550

700