Articles on: Learning & FAQ

How to Calculate the Actual Output Torque of A Gearbox?

A gearbox, also known as a reduction gearbox, is a device commonly used in mechanical transmission systems. Its function is to convert the input speed and torque of a motor or other power source into an output speed and torque suitable for a specific application.

Through different gear combinations, the gearbox can achieve different speed ratios and torque outputs, and is an important part of the mechanical transmission system. The most important role: reduce speed, increase torque.

NOTE: Gearboxes do not generate torque, but transmit it.

The rated torque of the gearbox refers to the maximum torque that the gearbox can withstand when it is designed. Exceeding this torque will cause the gearbox to be damaged or fail. The instantaneous allowable torque refers to the maximum torque that the gearbox can withstand in a short period of time, usually within a few seconds or less. The instantaneous allowable torque depends on the design and material selection of the gearbox, as well as the load and working conditions it bears.

Normally, the output torque of the gearbox should be less than the rated torque to ensure that the gearbox can work normally and have sufficient life.

The actual output torque of the gearbox is the actual output torque after the reducer is equipped with power. The specific calculation can be obtained by the following formula: Gearbox output torque=motor torque*reduction ratio*gearbox efficiency. Take 17HS15-1584S-MG10 as an example. This product is equipped with a MG17-G10 gearbox on the 17HS15-1584S motor.

The torque change before and after the gearbox is installed is shown in the figure below:

Motor SpeedMotor Torque(Nm)Gearbox speedGeared Motor Torque(Nm)Motor Torque*Gear Ratio*Efficiency

It can be seen that after the motor is equipped with a gearbox, the actual output torque of the gearbox is basically consistent with the calculated value. Therefore, we can flexibly choose the combination of gearbox and motor with different reduction ratios when large torque is required.

So is the gearbox with a larger reduction ratio more capable of outputting torque?
The answer is no. When choosing a gearbox, it is not that the larger the reduction ratio, the greater the output torque of the gearbox. The theoretical value calculated by the formula must not be greater than the rated torque of the gearbox, otherwise it will affect the service life of the gearbox and even cause damage to the gearbox.

Updated on: 31/10/2023

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