Why doesn`t vex sell 3 wire motors?

Wouldn`t they be the easiest motors to use for brains pic/cortex And signal spliters. because you do not need a motor controller.(29)
You could save some money and time.

Yeah they would be, and they also don’t burn out as fast as 269s do. :confused: But they have plastic internal gears and the 2 wires have metal gears. I do like 3 wires, since they are much easier to use. I really don’t know why they stopped selling them.

in stead of making a new thread also what is a good compimised gear ratio?
(more towards Torque than speed but still good.)

They could slightly raise the price and make metal gears. right?
And i think all the teams everywhere could benifit.

If you want to do a gear shift for torque, 5:3 is a good ratio.

The cost assumption is just completely false if comparing a 2 wire to a 3 wire. Right now we sell the VEX 2 wire motor + motor controller for the same price as the old 3 wire motor.

The old 3 wire motor had the motor controller built in to the motor itself. If you want to expand a system to different kinds of motors, then keeping the motor controller inside the motor is just not smart.

Right now, with 2 wire motors there is much more flexibility as you can plug the motor in to a 2 wire port directly or use a motor controller to use one of the three wire ports. In addition, if the direction of your motor is wrong, then you can just flip the two wires (red to black, black to red) and change the direction.

We stopped selling them because the components we used in those motors costs were increasing exponentially and raising the end user price was just not acceptable to us.

Actually, this is incorrect. One of the reasons VEX separated the motor controller & the motor was because in the old 3-wire motors that had internal motor controllers, sometimes the motor controller would break but the motor itself would be fine. There was really no way to repair this and you had to throw away a perfectly functional motor.

Now if a motor controller goes up in smoke, you just replace a 10 dollar part instead of the entire motor, saving you money.

Edit: See Paul’s statement… he is the VEX Robotics President after all.

We also save lots of money by not buying clutches for the new motors.

+1 (10 char)

You do have to be more careful with the 2-pins being more fragile. We’ve broken a couple, and we never did that with the 3-pin configuration.

We have found clutches to be useful in preventing 2-wires from overheating and breaking, so we still use clutches for certain purposes.

We haven’t used a clutch in a while. What real purpose does it serve?

The clutch is used between a power source and whatever that power source is driving. If the thing that it’s driving locks up, instead of the power source getting damaged, the clutch will dissipate the energy from the power source. For the little green clutch that you get from VEX, you would connect one end to the motor, and the other end to your mechanism. If the mechanism locks up while the motor is spinning (eg. your wheel cannot spin), the clutch will start “popping” and prevent your motor from getting damaged/overheating.

In a 2-wire motor, it can prevent your gears from stripping or your motors from breaking (which a great many teams this past year would’ve appreciated on their drivetrains). We found that they also go a long way in preventing drive and lift motors from overheating.

Thanks for this explanation. Needed a refresher.

And some of us still have the Three Wire Motors, that need to have the Clutches installed…

Well, you don’t absolutely need the clutches, I just built a robot that used 3-wire motors without clutches. Instead, I used shaft collars due to space reasons. Nothing broke in the short time that I tested them.

If you install the Clutches, and when driving you Bot, you don’t hear the Popping Sound of the Clutches, then you can get by without them… Your not Pushing the Motors that hard…

The most strain is when having a heavy Robot, and going from Full Speed One direction to Full Speed the Other… You will get the Clutch Pop as the Motor Reverses, and the Robot hasn’t ( yet ). Without the Clutches, the Motor Gears break…

Its pretty epic how most NZ teams only use 3 wire motors, and 4 high strengths. It has something to do with 2 wire motors locking up with too much stress on them, while 3 wire motors keep going and just strip the internal gears?

we just went through our annual “motor bucket cleanup/fix”
and guess what?
90% of the “working” motors were 3-wires…
most the two wires, when they “die” its the internal DC motors that crap out
which is impossible to fix
so we just gut the entire motor and everything from that is now “spare parts”
(gears, housing, screws, EVERYTHING)