strength AND speed

how can i make my robot go very fast without the motors locking up when i get in a pushing battle with another bot? i know there is a shutoff for the motors if they draw over 4 amps or something like that? is there a possible way to override that? or whats the best gearing system to go faster than 1:1 but be strong and not lock up? i am using 2 269 drive motors and any of the 3 wheels are available.

Your trying to pull power out of thin air… It’s not likely to happen. If you want speed, you need to sacrifice torque. It you want torque, you need to sacrifice speed. Also, I don’t think there’s anyway to override the motor. I tend to like the 4" wheels. They give a good speed and torque in 1:1. That should give you a benchmark to go from.

well make a transmission hah, have fun. actually they are sort of simple to make with pneumatics, but it kind of take ups some space depending on where you put it.

One thing to keep in mind when gearing a robot is the weight of the robot. If your robot weighs more than four or five pounds, two 269 motors 1:1 driving four inch wheels will most likely cause you some trouble in a pushing match.

It is very important to understand what exactly causes this trouble. Sometimes, it is caused by drawing too much current from the microcontroller causing a momentary failure of all the motors connected to the reset fuse. However, I have found that more often than not (at least on drive bases), the problem is heat. In my experience, 269 can be a pain and definitely don’t have nearly the headroom as the 393. If you still can only afford 2 motors for a drivebase, two 393s at 1:1 on 4" wheels might allow you to just scrape by with enough headroom to survive a pushing match.

its not that i cant afford them, but its through a school class so bigger motors arent offered. sounds like a good idea though, when i move to the advanced class they might be in our kits.

can anyone post a link to a transmission with two drive motors and one motor used to switch gears? thanks in advance

Topgun - think about starting a club and doing some fund raising, if you are participating in the VEX Robotics Competition. Then you could afford some parts not found in the classroom kits. You might talk to your teacher about this.

Right there is a pretty decent picture that demonstrates the concept of the transmission with motor. If you have pneumatics available i would use them instead because with pneumatucs you have linear motion instead of on a motor you have rotational. It still works with a motor but it is more efficient and easier to use (in competition anyways, not sure if it would make a difference though because it sounds like your doing this for school).

easy, hook up more motors :wink:

Since there are at least 6 wheel types available from Vex,
this sounds like a classroom competition with rules and objectives you have not fully explained.

Classroom competitions are won by

  • luck
  • good building practices
  • sometimes by doing something that others aren’t, like a different gear ratio
  • practice driving, plus native driving skill
  • matching your strategy to play to the strengths of the robot you have
  • matching your strategy to the weaknesses of your opponent

You’ll get more traction by moving the battery over the driving wheels.