Stronger motors

i know that this has been discussed a lot before, but i’m not sure if Vex heard our request for stronger motors when they were making new parts. I would really like to see a stronger motor for drivetrain applications. i was thinking simply more windings on the armature and a longer armature itself to provide more torque. i think vex should really consider this because i heard that during competition motors often overheat because those small motors have a hard time pushing a 15 lb robot and that i just want more torque without having so much of a reduction which brings the speed down a lot. i see lego has come out with multiple types of motors for different applications. i would like it to be affordable, around $25-$35. Not to say that the guys at vex are doing a bad job, i’m just suggesting.

I agree with you stronger motors without losing speed would be great
a different ratio in the gearing would suffice for this

A change in gearing to increase speed would result in a loss of torque.
A change in gearing to increase torque would result in a loss of speed.

A gearing change won’t do it.

The only time you would need a higher powered motor is if you wanted comparable torque at a higher speed, or more torque at the same speed.

The only problem with a higher power motor is that you couldn’t use as many of them. A higher powered motor with the same speed would draw more power.

I would still want them, as I could use a more powerful motor once in a while.

Which more batteries would be needed to supply the more power, resulting in more weight, resulting in a need for bigger motors… Resulting in a never ending battle…

I partly agree with everyone. Stronger motors would really be helpful, but if the motors are too strong, all the parts would have to be stronger, and it would result in paying more $$$, so that might not be that great.In some applications, it might be good, though.
If the motors were faster with more torque, that would be cool. You can have a fast but strong drivetrain or arm.
If you want to make a strong drivetrain for a heavy robot and you don’t want to sacrifice speed, you can just add on a few more motors for torque. To avoid the problem, you can just use aluminum.

yeah, but i don’t have $100 to spend on aluminum. i’d rather have a $30 solution.

Just an observation, but I suspect the folks at Vex are already thinking about more powerful motors. Remember that they announced the VEX Pro Controller. This is based on the “Qwerk” controller, which has 4 DC motor outputs.

The FAQ has a conceptual drawing of it that shows 8 screw-terminals, which seems to imply something other than their current line of motors and servos.

I realize that product is still being figured out and the drawing is not a final design, but I’m hoping they’ve got some unannounced products on the horizon in the motor department.


  • Dean

yeah that new controller does look pretty enticing, but i hope i can afford it (i probably won’t)

Now that’s a pretty sweet looking controller.

assuming that this controller is capable of handling the output from a full compliment of higher powered motors without its fuses tripping, the I see no problem with higher powered motors other than nth need for a larger battery. it would still be practical to have higher powered motors on the current controller as long as they were on a robot that is only using a few motors. For example, it’s a serious pain to design a robot for speed using only two drive motors and have it be able to go anywhere :mad:

Translation: i need to buy myself more motors.

I used to have 10Ah NiMH batteries and RC motors which draw up to 20A of current. The motor drivers for them are rather huge, but the sufficient power opens up many possibilities.

20 Amps!!! that’s like a ******* air conditioner!

Just remember 20 amps at a few volts is a whole order of magnitude different than 20 amps at 120 or 240 volts in terms of power.

Power (Watts) = Voltage * Current (amps) → P=VI

12 volts * 20 amp = 240 watts. A CIM motor from FRC under a moderate load will draw about this much current.

120 volts * 20 amp = 2.4 kilowatts, or 2400 watts.

The motors were rated about 40W but the current spikes can be quite high.

I’ve got a qwerk and these jameco motors and it works great.

But I want to use a vex track kit. I’m still new to robotics so I’m short on terms but i noticed the shaft(?) hole on the tank tread kit is square and the jameco motors use a hub to connect to a wheel. Any thought on how to use the jameco motors with the tank treads? Maybe a gearbox?


Can you be a little more specific about what you are running into that makes it seem that the motors need to be stronger?

Because John nailed it. If you need more power from an electric motor, then you have to gear it down. Gearing it down means it will be slower. That’s how the physics works out and nobody can change it. And scaling it up would mean changing a lot of things, not just the motors.

If you need fast AND powerful, then maybe electric motors are not the answer. When we run into those requirements in FRC, we often turn to pneumatics. And VEX does have pneumatics, but I’m not sure if you can use them in your competition.

Since I don’t know what your building I can’t say if pneumatics could work for you, but pneumatics do have several advantages. Power with speed is one of them. Another is that those tanks of compressed air are like adding more batteries (storage of energy) to your robot.

If anyone wants to learn the basics of pneumatics, Team Da Vinci has a wonderful page to help you out:


PS – When the heck is the gyro going to be out?

more powerful motors would be great for my purposes. The extra draw would hardly be noticed in a 2 min match. Plus, more powerful batteries aren’t noticeably heavier and we’ve been needing vex to make a better one for forever. It’s really a pain to easily get better batteries and not have them be competition legal.

I’ve used MFA gearmotors with great success before, check these out:

P.S. they aren’t competition legal, but good for your own projects should you need them

so how did you mount that motor with the round shaft to the square shaft? it looks really strong, just what i need to take over the world…i mean, uh…

output is a D shaped axle. You can use a wheel/hub which takes in the D shaped axle, or use a coupler to couple the output to the square axle.
You can also look for a spur gear which has the same pitch as the vex gears and fits the D axle.