# Can gears increase Holding Torque of a stepper motor?

1. Apr 13, 2013

### phys_student1

Hi,

I know you can use gears to increase the torque of a motor while it is rotating, but what about when it is still? Will the holding torque be any different from the case without gears?

I expect that there won't be any advantage, but want to make sure.

2. Apr 13, 2013

### Staff: Mentor

You can increase torque without rotation, too. It is the same concept.

3. Apr 13, 2013

### phys_student1

Interesting, can you guide me to a scientific reference (book, magazine, or any 'scientific' website) ?

4. Apr 13, 2013

I mean, you don't need a reference. You just need to know
$$\vec{M} = \vec{r} \times \vec{F}$$

5. Apr 13, 2013

### phys_student1

Thanks I know it.
But if I can always use some gears to increase torque then why would I ever buy an expensive motor with high holding torque? Because it is simpler?

6. Apr 13, 2013

### phys_student1

I also have another question.

Using gears with the motor will require the use of bearing. For two additional gears there will be some four bearings to support. The bearing themselves are not cheap. What is, then, best trade here? Going with high torque motor w/o gears or low torque w/ gears and bearing?

7. Apr 13, 2013

### Staff: Mentor

Well, then you need a gear with high holding torque. In addition, I don't think holding is the only thing the motor should ever do - otherwise you can just fix the stuff to the floor/wall/ceiling.
I think that really depends on the application.