Does motor torque increase as the speed reduction ratio increases? What is the formula for determining torque?
This column introduces the concept of motor output torque when installing a gearhead, including calculation formulas.
Heavy, heavy!!
Vex, hurry up and bring your stuff!
But, Ms. Ori, this luggage is really heavy! I wish it could be carried on a conveyor. I wonder if it could be carried by increasing the torque with the gearhead. After all, if the speed reduction ratio increase, the output torque will also increase, right?
That's right.
Calculation formula for determining output torque at gearhead installation
I believe that the permissible torque for gearhead installation can be calculated with the following formula, right?
Tg = Tm × i × η
Tg: Output torque at gearhead output shaft
Tm: Motor torque
i: Speed reduction ratio of gearhead
η: Transmission efficiency
For example, if we consider induction motor "4IK25GN-AW2J" and gearhead "4GN180K" to be combined with it, we can see the following:
Tm: 205 mN·m [for 50 Hz] η: 66 %
I think. So, if you apply that figure to the formula above, the output torque would be about 24 N·m.
Tg = 0.205 × 180 × 0.66 = 24.354 N·m
In other words, the higher the gearhead's gear ratio (i), more torque will be produced, right?
That's right. But, Vex! It doesn't mean that the calculated torque value can definitely be applied. Actually, the gearhead has a fixed permissible torque, and there's an upper limit to the load torque.
What?! Really?
Permissible Torque Concept
Gearheads use gears and bearings, but there is a limit to their mechanical strength due to the materials, size, and other factors. The permissible torque value is determined based on this.
Hmm. So what happens if you apply more torque than the permissible torque?
In the gearhead design, the mechanical strength is about 1.5 to 3 times the maximum permissible torque. So, it is very unlikely to be damaged by a brief overload, but depending on the frequency and duration of use, it can have a significant impact on its lifetime. Therefore, it wouldn't be recommend using it beyond the maximum permissible torque.
Oh, I see. Then the maximum permissible torque for the "4IK25GN-AW2J" and "4GN180K" is 8.0 N·m, right? Therefore, if you use it within that range, it will have an advantage in terms of longevity.
That's right! Oh! By the way, Vex, the conveyor is driven by a motor to carry luggage?!
That's obviously a joke! Please don't tease me!
Ok, ok! Then let's get this luggage out of here!
Key Points of this Time
Output torque at gearhead installation
The output torque of the motor increases in proportion to the speed reduction ratio of the gearhead.
Permissible Torque Concept
The output torque at gearhead installation can be determined by motor torque × speed reduction ratio × transmission efficiency. It is not recommended to use more than the maximum permissible torque determined by the specifications as it will affect the lifetime.
