Torque calculation or clarification please

[achi]

Hi,

I have looked at several sites each posting conflicting information, so I am uncertain that the real answer I am looking for is not expressed properly in a web search. I am hopeful that any mech eng or person knowledgeable will be so kind and assist. I am not an engineer.

Here is my question and I am guessing for some this is pretty simple.

One shaft has 2 gears (Gear 1= 3" diameter, Gear 2 = 5"), the rpm of the gears will be the same given they are on the same shaft, but will they have the same torque when each of those gears connects to another gear?

Hope this question isn't too stupid to ask.

Thanks in advance, and thank you very much for the clarification (education)

Cheers,
Achi

[narly1]

Gears don't generate torque, instead they transfer it as rotational energy.

The shaft that the two gears are mounted imparts a torque onto the gear.

The gear then imparts this energy onto a mating gear via the teeth on its circumference.

The First Law of Thermodynamics (Conservation) states that energy is always conserved, it cannot be created or destroyed. In essence, energy can be converted from one form into another.

So other than the energy lost to spinning up the mass of the gear, frictional losses at the gear teeth meshing, etc., most of it gets transferred.

[Papa]

Torque will be greater for the larger gear. The formula for this is T=F x L, where F is force and L is the distance from the center of rotation (radius of the gear).



https://khkgears.net/new/gear_knowle...on-torque.html

Dave

[NAZ]

Achi, what is it exactly that you are trying to understand? In an automotive context, gears are typically used in power transmission applications to transfer rotational motion or to create a mechanical advantage. Are you trying to understand how torque is multiplied?

[achi]

Hi and thanks for the replies and the site link!

It is for no project other than personal knowledge and education for me and not in an automotive context. I looked at the site khk gears but it still was not clear for me. I do see how L would affect torque from the diagram. This may be one of those things for me not easily understood and maybe I am making something very simple very complicated.


I guess what I was thinking was,
The amount of torque to spin both the gears would be equal as they are both being spun from the same axis. But if one gear is larger than the other, is more torque required to spin that larger gear on the same axis? Is something greater generated from the larger gear than the smaller gear if they are each connected to another gear? Maybe it is not torque that is calculated when that first gear is required to spin a second gear connected to it which sits on a secondary axis. Not sure if I am being clear..sorry for that. (My understanding of torque goes about as far as using a torque wrench.)

On another note, if you take a gear that has to spin another, do you have to figure out how much torque will be required to turn it, or is it just simply if it has enough power it will move it.

Again, thanks for the education, and helping me to understand, hopefully not being too much of a bother.

Cheers,
Achi

[bobl]

Here's my simplistic explanation. EX: You have your input shaft with 2 gears being turned by a 100 lb. ft. torque constant speed motor. Connected to this are 2 gear driven shafts. One driven at 1/2 speed and the other driven at twice the speed (for simplicity). So, 2:1 gear ratio and 1:2 gear ratio. Removing all the losses from friction, heat, mass, etc if you were to measure the torque output of the 2 driven shafts with a torque transducer you would find the 2:1 shaft producing twice the torque at 1/2 the rpm. Conversely the 1:2 shaft would produce 1/2 the torque but at twice the speed. So the actual work being produced is equal If this example were an automotive engine and transmission the Hp would always be equal at the output of the transmission even though the torque output changed (along with the rpm) Horsepower being just a calculation of TQ X RPM / 5252 = HP Hope this helps answer your question, or add confusion as the case may be.

Bob