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I'm not good in math or physics in general. It's hard to me.

In a DC motor which from start to end take 1 unit of time with 1 unit of weight loaded is the same thing than 2 units of time with half-weight.

The reason I ask this is because I have an old car-window motor weak, I want to increase it's torque by halving a bit the gear.

It will have more torque, it will take more time to finish. But, does it consume the same power in the end changing one for another? If yes, I take a better approach.

I'm assuming normal condition with naturals losses everything has.

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Force x distance equals energy consumed in the exertion of that force to move something that distance.

If the thing is moved in half the time, the energy consumed is the same but, given that power is rate of energy consumed, the power will be double.

For a motor, power is proportional to both torque and speed of rotation so, if a gearbox is used, torque doubles but speed halves therefore power is the same.

Losses in the gearbox and drives alter this a bit but the general principle remains.

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  • \$\begingroup\$ Force x Distance was the principle I was looking for. I had ignored all other physics losses to keep my point simple. Thank you, I was leading to right direction and avoiding some wrong-empirical logic. \$\endgroup\$
    – Ismael
    Jan 7 '16 at 10:45
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Assuming the window motor was once able to move the window, then we know something has changed, but not what, nor where. The motor may need cleaning and lubrication to overcome increased friction due to dirt in its bearings. The window tracks may need a similar treatment. Either of these could now require more torque from the motor than it was designed to deliver.

Or the wiring from the battery and switch to the window motor may have deteriorated over time to make it less capable of delivering the current it once was at the motor's design voltage.

We can't tell from the information in your question where the deficiency might have occurred, and therefor whether changing the gearing will fix the issue or only the symptom.

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  • \$\begingroup\$ Indeed, this will be made because the machine-spirit is in pain, I cannot continue like that. But I was in doubt if increasing the torque would spend less power (watts per minute or any energy unit per time). I didn't want to live in a bliss assumption. \$\endgroup\$
    – Ismael
    Jan 7 '16 at 10:49

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