torque or rpm

sarathyplkr5

hi .. ...
i am entering a sumobot competition..weight limitation 1kg..dimensions 150mm*150mm...what is more important
torque or rpm...say i have 10 rpm motors with 38kg torque ...and ..60 rpm motors with 20 kg torque...which should i go for...due to the size limitation ..i can go only for 2 motors...any comment is appreciated... Wink

emKhairol

Every single things are not perfect. They will come with pros and cons. With this kind of competition, I would go for TORQUE.

Put it this way, just imagine a big truck can carry a load that heavier than its weight. Even it move at low rpm but still can pull its load with high torque.

In your case, you are about to build a sumo robot, I suggest you go for a motor that has a higher torque than rpm itself.

Just my humble opinions.

sarathyplkr5

thanks a lot...

A.T.

If you gear down the 60 rpm motor to 10rpm, it will give you 6 times the torque it had at 60 rpm. What matters is power = torque x angular velocity. In your example the 60 rpm motor has much more power, so it can potentially create more torque at the same angular velocity.

rcgldr

Assuming you can gear the motors, then you're looking for power that is geared down so that the geared down and multiplied torque is at a maximum. See if you can get the specific motor performance curves for the two motors you're considering.

Note that electrical motors usually produce peak power at 1/2 the maximum no load rpm, but will generate more torque at lower rpms than higher rpms. Link to article that explains this:

dc_motors.html

You'll need to decide on a trade off of speed versus the torque after gearing reduction of your bot when choosing the motor and the gearing.