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Load Torque Calculation Formula

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Motor Shaft Conversion Torque: TO

Z1 : Teeth number of the motor-side gear
Z 2 : Teeth number of the load-side gear
R : Gear ratio Z2/Z1
η : Transmission efficiency % /100
T : Load-side torque[N・m]

To= R・T [N・m]
η

Torque when Adding the External Force of the Rotating Object: T

D : Diameter of the drum [m]
F : External force[N]

T= 1 D・F [N・m]
2

Torque by Friction Force of the Feed Screw and External Force: T

P : Feed screw lead[m]
M : Mass of the load [kg]
g : Gravitational acceleration[m/s2]
μ : Friction coefficient of the feed screw
F : External force[N]

T= 1 P(F+μMg) [N・m]

(Normally, μ : approximately 0.05 to 0.2)

Torque by Friction Force of Rack and Pinion and External Force: T

D : Diameter of the pinion [m]
M : Mass of the load [kg]
g : Gravitational acceleration[m/s2]
μ : Friction coefficient of the rack and pinion
F : External force[N]

T= 1 D(F+μMg)[N・m]
2

(Normally, μ : approximately 0.08 to 0.1)

Torque by Friction Force of Conveyor and External Force: T

D : Diameter of the roller [m]
M : Mass of the load [kg]
g : Gravitational acceleration[m/s2]
μ : Friction coefficient of the conveyor
F : External force [N]

T= 1 D(F+μMg)[N・m]
2

(Normally, μ : approximately 0.05 to 0.1)

* The friction coefficient value μ varies depending on the machine processing accuracy, lubrication condition, and other factors.
  Pay enough attention when calculating the load torque.
* The transmission efficiency η between the motor and load varies depending on the connection method. The following shows typical values.
Spur gear: 0.85  Chain: 0.9  V-belt: 0.9

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