How to Calculate Drivetrain Torque

Hello everyone,

I was thinking of testing different drivetrains for our robot, some which gear up and others which gear down. I was wondering how exactly I could calculate the torque that my drivetrain would produce. Furthermore, if someone could help me understand how the torque number relates to the weight that the robot can push, that would also be great.

Much thanks

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There’s a pretty useful online calculator I’ve used.

http://wentec.com/unipower/calculators/power_torque.asp

You can change HP to kW, which is kilowatts. You find that by dividing your volts by 1000, with the max being .012 for the VEX motors. Then just put in your RPM, and it will tell you how much pressure is being output by your drivetrain in whatever direction you are facing in pounds per inch. You could also change it to N.m (newton meters) which would give a more scientific answer, but it is a little harder to quantify

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I don’t have a v5 brain with me right now, but doesn’t the brain, when in manual device control show a torque rating on the graph? I know it shows rpm, watts, and a torque graph… not sure if it has actual numbers on it.

But a drivetrain is different than a motor:

If weight distribution is bad, wheels will spin.

If front/back wheels are not joined together w/ gears/chain then tractive force is less if/when you experience wheelspin.

Friction also plays a part, especially if build quality is poor.

From a competition perspective, you need traction, power, and speed, a fine balance of each.

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