alokpatra said:
am nt sure if am posting in the right section bcoz this is my 1st post..
please could i get help in understanding how to increase the torque of a dc motor without changing the rpm..
n how are gearboxes designed exactly which increase torque..
i basically want a mechanism 2 deliver higher torque maybe some way 2 increase torque externally (outside the motor )to use in ROBO WARs...
Welcome to PF. You are in the right section since this is a general question. If it was a specific homework problem it would go up in the homework section.
As for your problem, the simplest solution is a gear box. The long story short with gears:
A smaller gear that turns a larger gear will turn the larger gear slower, but with more torque.
A larger gear turning a smaller gear will turn the smaller gear faster, but with less torque.
The gear ratio is the ratio of the RPM in and out of any group of gears.
I don't know what kind of physics background you have, but torque is just a force that causes rotation. Torque itself is calculated by multiplying the force that is perpendicular to the axis of rotation by the distance from the axis, or the "lever arm".
In this animation the dark blue arrow that appears on the ball is the force that creates the torque. The lever arm is the length of the arm that goes from the axis to the ball.
Same idea with a see saw. If you place the fulcrum (point of rotation) three quarters up the board and place a big mass on the short end you'll be able to counter balance it with a lighter mass on the other side, because of the longer lever arm.
Gears follow the same principle, the larger gear has a much larger radius that it exerts the force over, as opposed to the smaller one. So that's how it works.
"Gear reduction" basically sums up to less speed, but more torque. Which is what you're looking for. For robotics specifically you should be able to find pre-made assemblies in hobby shops, or just pick up some gears and experiment with different ratios yourself.