Gearbox -physics related question

[sporno]

so whats this mean in a nutshell , im kind of lost

[MrForbes]

In a nutshell, what it means is that you're probably not going to gain the benefit you though you might, from lightening the rotating parts in a robot gearbox.

Originally Posted by sporno

If i cheesed a couple of the gears in the AM , or KOP gearboxes , decreasing rotational inertia , and rotational mass , would that have any effect aside from just cutting weight?


would it actually put more power to the ground , and create less drive train power loss?

It would put a little bit more power to the ground as you are bringing the robot up to speed--that is, it would help you win a "drag race" against another robot. But it will not give you any more pushing power, because once it is up to speed (or when it is standing still) there is no more gain from the lightening.

The idea might be useful for an arm, though, as it will take less power to raise an arm that has less inertia. So, when you are doing arm design, keep the weight at the outer end to a minimum!

[sporno]

The drag race is exactly what i was getting at , and the power power to the ground

lets say you were ramming another robot ( i know not legal)

but if you got up to speed quicker would that change the momentum that someone was hit with?


Was i sorta right about the first topic

[MrForbes]

Hmmmm.....I dont' know whether or not you would have more ramming energy with more speed and less flywheel inertia, or the other way around, or the same. Interesting question.

Let's say you have two robots, Robot A has normal unmodified gearboxes. Robot B has gearboxes with very lightweight gears in them, so they can "spin up" faster given the same motor torque as Robot A.

Robot B would win a drag race, that is it would accelerate more quickly. However, Robot A would win a "coasting" race, as that extra energy stored in the heavier rotating gears would keep it moving longer than Robot B, after you turn off power to the motors.

[sporno]

well knowing this, someone can dial in their bots a bit more

[chris31]

I dont have Inventor, but has anyone taking the AM shifter gearboxes and seen how much you can remove from some of the gears. And then from this calculate the weight saving, any acceleration benefit and any weakness you creat in the gears by doing this?

[sporno]

this past year my team cheesed our gear boxes , we cut off some weight , but we never calculated anything that this thread is about

[MrForbes]

This past year 1726 left the chassis and drivetrain heavy, and the robot never fell over (unlike the previous year)