Full load motor torque ![full load motor torque calculation](/getattachment/Resources/Useful-Formulas/formula-1_1.JPG.aspx) |
Horsepower (P), hp
Shaft speed (N), rpm
5252 = Constant
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![formula for full load motor torque given horsepower and shaft speed](/getattachment/Resources/Useful-Formulas/Formula-1.JPG.aspx) |
Average dynamic braking torque ![adverage dynamic braking torque calculation](/getattachment/Resources/Useful-Formulas/formula-2.JPG.aspx) |
Total inertia reflected to brake ![calclation for total inertia reflected to brake](/getattachment/Resources/Useful-Formulas/formula-2_2.JPG.aspx)
Shaft speed at brake (N), rpm
Desired stopping time (t), seconds
308 = Constant
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![formula for average dynamic braking torque given total inertia, shaft speed and desired stopping time](/getattachment/Resources/Useful-Formulas/formula-2_3.JPG.aspx) |
Static torque (T), lb-ft |
Force (F), lb
Pulley or drum radius, (R), ft
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![formula-3.JPG formula for static torque, given force and pulley or drum radius](/getattachment/Resources/Useful-Formulas/formula-3.JPG.aspx) |
Overhauling dynamic torque reflected to brake shaft ![formula-4-(1).JPG calculation for overhauling dynamic torque reflected to brake shaft](/getattachment/Resources/Useful-Formulas/formula-4-(1).JPG.aspx) |
Weight of overhauling load (W), lb
Linear velocity of descending load (V), ft/min
Shaft speed at brake (N), rpm
0.158 = Constant
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![formula for dynamic torque given weight of overhauling load, linear velocity and shaft speed at brake](/getattachment/Resources/Useful-Formulas/formula-4_4.JPG.aspx) |
Static torque of brake ![calculation for static torque of brake](/getattachment/Resources/Useful-Formulas/formula-5.JPG.aspx) |
Dynamic braking torque required ![calculation for dynamic braking torque](/getattachment/Resources/Useful-Formulas/formula-5_2.JPG.aspx)
0.8 = Constant (derating factor)
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![formula for static torque of brake given dynamic braking torque required](/getattachment/Resources/Useful-Formulas/formula-5_3.JPG.aspx) |
Inertia of rotating load reflected to
brake shaft ![calculation for inertia of rotating load](/getattachment/Resources/Useful-Formulas/formula-6-(1).JPG.aspx)
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Inertia of rotating load ![calculation for inertia of rotating load](/getattachment/Resources/Useful-Formulas/formula-6_2-(1).JPG.aspx)
Shaft speed at load ![calculation for shaft speed at load](/getattachment/Resources/Useful-Formulas/formula-6_3.JPG.aspx)
Shaft speed at brake ![calculation for shaft speed at brake](/getattachment/Resources/Useful-Formulas/formula-6_4-(2).JPG.aspx)
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![G formula for inertia of rotating load reflected to brake shaft given inertia of rotating load, shaft speed at load and shaft speed at brake](/getattachment/Resources/Useful-Formulas/formula-6_5.JPG.aspx?width=175&height=39) |
Equivalent inertia of linear moving load
reflected to brake shaft ![calculation of equivalent inertia of linear moving load reflected to brake shaft](/getattachment/Resources/Useful-Formulas/formula-7-(1).JPG.aspx)
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Weight of linear moving load (W), lb
Linear velocity of load (V), ft/min
Shaft speed at brake ![calculation for shaft speed at brake in rpm](/getattachment/Resources/Useful-Formulas/formula-8-(1).JPG.aspx)
2 = Constant
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![formula for equivalent inertia of linear moving load reflected to brake shaft, given weight, linear velocity and shaft speed](/getattachment/Resources/Useful-Formulas/formula-9.JPG.aspx?width=175&height=42) |
Kinetic energy of rotating load, ![calculation of kinetic energy of rotating load](/getattachment/Resources/Useful-Formulas/formula-10.JPG.aspx) |
Inertia of rotating load reflected to brake shaft
Shaft speed at brake ![calculation of shaft speed at brake](/getattachment/Resources/Useful-Formulas/formula-11_3-(2).JPG.aspx)
5875 = Constant
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![formula for kinetic energy of rotating load given inertia and shaft speed](/getattachment/Resources/Useful-Formulas/formula-11_2-(1).JPG.aspx?width=100&height=37) |
Kinetic energy of linear moving load ![calculation of kinetic energy of linear moving load](/getattachment/Resources/Useful-Formulas/formula-12-(2).JPG.aspx) |
Weight of load (W), lb
Linear velocity of load (v), ft/sec
g = Gravitational acceleration constant ![gravitational acceleration constant of 32.2 feet per second squared](/getattachment/Resources/Useful-Formulas/formula-12_2.JPG.aspx)
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![formula for kinetic energy of linear moving load given weight of load, linear velocity and gravitational constant](/getattachment/Resources/Useful-Formulas/formula-12_3.JPG.aspx?width=69&height=39) |
Change in potential energy (PE), ft-lb |
Weight of overhauling load (W), lb
Distance load travels (s), ft
|
PE = Ws |
Total energy absorbed by brake ![calculation of total energy absorbed by brake](/getattachment/Resources/Useful-Formulas/formula-13.JPG.aspx) |
Total linear kinetic energy ![calculation of total linear kinetic energy](/getattachment/Resources/Useful-Formulas/formula-14_3.JPG.aspx)
Total rotary kinetic energy ![calculation of total rotary kinetic energy](/getattachment/Resources/Useful-Formulas/formula-14_4.JPG.aspx)
Potential energy converted to kinetic energy
(PE), ft-lb
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![formula for total energy absorbed by brake, given total linear and rotaty energy and potential energy converted to kinetic energy](/getattachment/Resources/Useful-Formulas/formula-14.JPG.aspx) |
Thermal capacity required for rotational or linear
moving loads (TC), hp-sec/min
|
Total system inertia reflected to brake shaft
Shaft speed at brake ![calculation of shaft speed at brake in rpm](/getattachment/Resources/Useful-Formulas/formula-15_3.JPG.aspx)
Number of stops per minute (n), not less
than one ![calculation of number of stops per minute, not less than one](/getattachment/Resources/Useful-Formulas/formula-15_4.JPG.aspx)
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![formula for thermal capacity required for rotational or linear moving loads, given total system inertia, shaft speed, and number of stops per minute](/getattachment/Resources/Useful-Formulas/Formula-15_5-(1).JPG.aspx?width=110&height=41) |
Thermal capacity required for overhauling loads
(TC), hp-sec/min
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Total energy brake absorbs ![calculation of total energy brake absorbs](/getattachment/Resources/Useful-Formulas/formula-16-(2).JPG.aspx)
Number of stops per minute (n), not less
than one 550 = Constant
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![formula for thermal capacity required for overhauling loads, given total energy brake absorbs and number of stops per minute](/getattachment/Resources/Useful-Formulas/formula-16_2.JPG.aspx?width=80&height=30) |
Linear velocity, ft/min |
N = rpm
Diameter (D), ft
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![formula for linear velocity given diameter](/getattachment/Resources/Useful-Formulas/formula-17.JPG.aspx) |