# Best motor/gearbox for lifting

What is the best motors and gearbox to use for lifting this year?

Whichever one works in your prototype. This isn’t a kind of thing other teams can answer for you.

Any motor can lift any load-- it’s just a matter of time.

If you want to hang quickly then you need larger/more motors trying to lift the robot.

Figure out how fast you want to lift your robot (how many seconds to lift)

Figure out how high you want to lift your robot (the change in height of the center of mass, in meters)

Figure out how heavy your robot is (in Newtons).

Then you can calculate the power (in watts) required to lift your robot the desired height in the desired time:

watts = Newtons*meters/seconds

Once you know the required watts, you know you’ll need a motor with at least that much power. To be sure, multiply by a safety factor.

Then, gear that motor so that when it is spinning at half free speed (max power), it will lift the motor the desired distance.

I know our team has designated 2 CIMs for hanging, but it is a high priority for our team, it really depends on how reliable you want it to be and how important it is that you hang.

my team is going with a bag motor and a versa 1:100 gearbox for lifting

…or, less robot.

Maybe this’ll be the first time in our history we don’t bother ballasting up our robot…we’ve done everything from steel I-beams to dumbbells last year (wrapped in black tape to keep with the theme).

Another concern you should have: Will the design hold position after the power is cut at the buzzer? Some designs will regardless of motor, others won’t.

Have you done the math to make sure you won’t exceed the torque rating on the output shaft of that 100:1 gearbox?

Then, divide the wattage by 12v and make sure you’re not going over the current limits of the breakers. If you are, you are trying to go too fast (or you’re too heavy)

Sparks

eek I have not where is this data?

edit: found it and it is thanks though for the thought I had visions of expensive motor/gearbox combos breaking

Close, but no cigar.

The motor wattage rating is the mechanical power at the output shaft, not the electrical power the motor is consuming.

But your point is well taken. The operating current should be checked.

You can find the operating current by using the motor curves or this motor calculator.

Fair point - but running at peak efficiency those motors are around 80% efficient anyway, so you can definitely get a ballpark assuming mechanical energy is equivalent to electrical energy. The actual motor model is a lot less fun

Sparks

We tested our lift today, and are certain that one CIM can do the job… But we are using two, even though the lift isn’t appreciably faster, just to be sure. (We have the weight, so the extra CIM is just insurance of the current/power variety.)

“Just To Be Sure!” could be the motto for our climbing team… We’re likely over-engineering everything, and adding in robot-safety features that really aren’t necessary, and we’re glad to do it!

Fun is a matter of perspective. I happen to think actual motor models are incredibly fun. :]

And motors running at maximum power are definitely NOT running at their peak efficiency. Current draw will be higher than you think.

Ether is right, you need to do the math. The calculators he pointed to will help you with that.

Adding ballast and needing extra weight is a foreign concept to us…