Ok so we need some help figuring out what type of gear ratio we should use for our lift. We are using 4 motors and a 10 bar lift. We have minimal parts which include: 2 12t high strength, 2 12t, 4 36t high strength, 2 24t, 2 60t high strength, and 2 60t gears. We need a ratio that is greater then 1/5 do u guys have any suggestions? We want something that can carry two cubes and doesn’t have to be that fast just not anything over a 1/25 ratio. Thanks for the help we really appreciate it! If anyone’s going to the Pwnament see you there! If the past I’ve had problems with chain but we also have 2 6t and 2 26t high strength chain gears if that would help at all but whenever I’ve used chain it tends to skip or not have enough power. Maybe we could use both but I don’t know what would be the smartest ratio for that.
Ok, so instead of guessing like my team, as well as many others, have done in the past, I am going to post a walkthrough of the math behind finding your gear ratio.
To start with, you are going to need to find the weight of everything you want to lift. This includes game objects, the metal on the lift, the intakes, motors, etc. + at least a 15% safety factor (screws, standoffs, spacers, etc.).
t = r * f, where t = torque, r = radius, and f = force.
The r is radius is the length of you arm. I don’t know how long your arm is, but this is r.
Force is the weight of what you are trying to lift.
Torque equals to the torque of four motors, since that’s what I read in your post, multiplied by your gear ratio. The torque of a single motor is published by VEX. So setting up your equation should be as follows:
t * gear ratio = radius * weight
And now you solve for the gear ratio. I’m not going to do that, since I’m going to assume you know your algerbra.
After all of that, you can make a chart of all the gear combinations. From here, you can see if you need to compound it, or if you don’t.
…and that’s it!
Do you have any high strength shaft? I’m not sure this is of any use, but maybe on each side of your lift you could use two motors to drive a single 12 tooth pinion gear, which drives a 60 tooth high strength gear. On the same shaft as that 60 tooth high strength gear you have a 36 tooth high strength gear. Then you have that 36 tooth high strength gear drive a 60 tooth high strength gear, which is screwed to your lift’s bar.
So that would be 12:60 and then 36:60 for a total gear ratio of about 1:8, I think.
Would that make any sense or am I having a brain fart about this?
Oops, I just noticed you don’t have enough 60 tooth high strength gears for that.
Let’s see…
You could have 2 motors power a 12 tooth gear, which then drives a 36 tooth gear. On the same shaft as that 36 tooth gear you have a 12 tooth high strength gear (pinion), which then drives a 60 tooth high strength gear. That would give you a 12:36 and then a 12:60 for a total about about 1:15, I think.
The problem is that you would be using two motors to drive a 12 tooth normal plastic gear and then a small shaft to transfer the torque from the 36 tooth gear to the pinion. And that would be likely to twist the shaft if not strip the gears.