Drivebase Speed and Torque

VEX Robotics Competition Discussion
1

Currently trying to decide on the gear ratio for my drivebase.

I’m planning on doing an xdrive, but I don’t want to go with the direct drive 200 rpm, since I feel like a lot of teams are going to do that, and I feel like speed is important.

However with the sqrt2 speed increase of an xdrive, there’s a 1/sqrt2 torque, and I’ve heard that you need torque in order to accelerate quickly to be able to get to your top end speed.

I was planning to gear down 600 rpm motors 60:24 (torque ratio, not sure which gear is meant to go first, driven or driver) to an rpm of 240, or effectively 330 rpm with X drive, but I don’t know how much that would affect the acceleration of our robot.

I plan to include pneumatic brakes so we can’t be pushed around easily, however we still wouldn’t be able to push others around

What do you guys think of that idea, or should I just go simple direct drive 200 rpm and be the same speed as everyone else, or should I try my idea.

2

24 tooth gears are not great, they have a lot of friction (as ive heard). I havent used many x drives but Fast X Drive - YouTube this video uses 257 rpm. And also, if youre thinking that other teams care whether or not you made something similar to them, they dont.

3

200 rpm 4in wheel x drives are plenty of fast for this years game. And once you start going faster, you will really start to feel the lack of torque. Plus, gear trains on x drives are incredibly complicated and annoying.

5 Likes
4

If you really want to do a geared x-drive, I would do 300 (600 motor geared 24:48 for torque) on 2.75 inch wheels. Equals about 290 rpm tank drive on 4" wheels.

1 Like
5

It’s not about if other teams care that I’ve done the same X drive rpm, but I want to be able to be faster than other teams, and if a large number of teams are direct drive 200 rpm 4in X drive, then we’ll all be the same speed.

1 Like
6

Yeah afaik you need to have the gears stacked vertically over each motor.

I just want to be faster than other teams, is the lack of torque that noticeable? What effects does it usually have?

1 Like
7

lack of pushing power and pushed more easily, just having an x drive in the first place makes you susceptible to pushing, I think that a traditional tank drive on 257 or 360 rpm will be one of the best options and used a lot

8

This topic was automatically closed 365 days after the last reply. New replies are no longer allowed.