A Question Of Torque

Question

I was wondering if someone could give me a little clarity here. If using gears to reduce a servo's / motor's rotation by 50%, will that increase it's torque per cm?

I'm going to be using a 40kg servo and I am going to reduce its rotation from 210 degrees to 105.

Rich · Accepted Answer

From what I understand and remember of the physics of torque etc. (it's been a while so double check this), if you use a 2:1 ratio gearbox the speed is half and the torque is double (excluding any mechanical losses of the gearbox). So, in this case, to move 105 degrees will take twice as long as before since the servo horn needs to turn the full 210 degrees still. And the torque will be 80kg/cm (less gearbox losses). I have assumed it follows the same laws of physics and principals as anything else however please feel free to double check and wait for other input on the subject.

Troy · Answer

If I understand you correctly, in short, yes. The force used in traveling is expended in a smaller number of degrees. I will try and find a link or two unless someone else does it first. Link1 This is a good one. Link2

Troy · Answer

I agree with Rich. Perhaps I didn't explain it properly. "I have assumed it follows the same laws of physics and principals as anything else ............." Puzzled....

Jaychadw · Answer

That's how I understood it to be. I remember when at school ( some 15 years ago ) I was quite good at physics. However now I'm trying to use it I find myself questioning myself.

Troy · Answer

Thats ok. You'ld be surprised what you can forget when you don't use it.

Rich · Answer

@Troy, why puzzled? FYI you hadn't replied when I started to reply so I had no clue about your reply if that's what was puzzling you @Jaychandw, it'll come back to you. It took a few weeks for my electronics knowledge to flood back to me when I hadn't used it for 15+ years.

Troy · Answer

@Rich Ah I see. I didn't realize I didnt hit send before looking for the links.

jstarne1 · Answer

@jay without getting complicated if you use gearing to reduce speed it will equally increase torque minus efficiency. Gears typically lose about 15 percent. So let's say you reduce the speed by half your going to double torque. Original torque 100 cm , reduce speed by half with gears gives 200 cm minus efficiency loss of 15% that's 170 cm estimated. This doesn't under mind others answers I just put a "simple" one out there.

Jaychadw · Answer

Sorry not been back for a bit, internet issues.

Thanks for that guys it really helps.

@everyone I am remembering bits and bats, getting the confirmation really helps. Thanks for he support. I just wish it'd come back quicker stress

@jstarne I'm definitely going to remember that in my calculations, reduce by 15%

@Troy Thanks for those links, immensely useful.

Jaychadw · Answer

Resolved by all

Jaychadw

A Question Of Torque

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