So our team uses a 24:60 gear ratio with 2.75” wheels. We have an omni on either end, and two traction in the middle. Our team wanted a really small drivetrain, and this is the smallest drivetrain you can make with 4 2.75” wheels (12T gears don’t work) But upon testing, I didn’t realize how slow 240 rpm can really be, since our motors are on the 24T gears. We have a tournament in a week, and we don’t have time to rebuild, so the only other option would be to move the motors on the 60T gears. However at this point, the 24T gears don’t do anything. Alternatively, we have a drive base that uses a 60:36:36:36:36:36:60 ratio, but doesn’t have much power. Any feedback or solutions? (If you need more info just ask) Thanks so much for your help!!
Move the motors to the 60t gears and keep the 24t gears. It will make your robot really quick and it’s a really solid and consistent drive. Look at 21417A Robotkauz they have been using this drive for the past couple of seasons.
side note: if you have your 24t gears not on screw joints and don’t have time to do that take them off and then put them on screw joints after the comp
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Thanks for your reply! We will take your feedback! What will screw joints do though, is it just less space? Also, is 600 rpm a little fast, or is it good for Over Under? Thanks so much!
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It’s the fastest gear ratio any team has ever been competitive with, but at this point, you don’t have many options. I do hope that you have a 6-motor drive though, because 600rpm with any less than that would be atrocious.
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You can do a 36:48 gear ratio (450 rpm), because it uses similar spacing to your current drive so it won’t be hard to switch too and is a much more reasonable speed then 600rpm. It is still a relatively fast speed though and I would not recommend it unless you have a 6 motor drive.
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Screw joints on drivetrains reduce friction considerably. Instead of a shaft, they use a screw and free-spinning inserts (though you can’t attach this to a motor) on gears not connected to the motor. Here is a post:
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I think 600 rpm is a little fast but it is also coming more into the meta of having a faster robot so I don’t think you will have any issues with it. I’m actually working on a rebuild for states and worlds that will be a 600rpm base.
screw joints reduce friction and brace the drivetrain at the same time without having to use bearings and shaft collars. ryan from 4253b has a great video on them here.
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dont do 60 to 24 if thats what you were saying thats over 1200 rpm which is unreasonable
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The wheels are on the 60-tooth gears, the only reason the 24-tooth gears exist are to transmit power between wheels. It’s still 600rpm.
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Your drivetrain being on 2.75” Omni wheels definitely is significantly affecting your speed. You should 3.25” at the smallest.
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I disagree. Especially this year, you want your center of gravity to be as low to the ground as possible due to all the defense and tipping going on. However, still make sure you’re able to go over the barrier.
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To each his own, I guess. All of the best teams in the world use 3.25” at the smallest and many use 4”. There are other ways to lower center of gravity. My robot uses 3.25” omnis and I’ve never managed to tip it over at 6 motor 450RPM speed.
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Are you sure? At least in the U.S. most teams are on 2.75s for the good COG and compatability with 600 direct drive.
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In Ohio I see most teams on 3.25” and the best team in the world according to true skill is 2011A and they use 4” omnis to go over the barrier very easily. I use 8 wheel drive on 3.25” and my center of gravity is still very low. I’ve never managed to tip it over or anything and my drivetrain is 450RPM on 6 motors. So any size can work. I’ve seen a couple of 600RPM direct drive drivetrains on 2.75” and I see the appeal, but it’s not for me.
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Just do direct drive with blue motors at that point
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Are you sure about that? I think the most prevalent gear ratios for this game are 600 rpm direct or 450 rpm, both on 2.75" wheels. Not trying to discount other drives, just giving my opinion.
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In Indiana rn most teams are on 3.25 360-400rpm gears included. But Robokauz currently is 600 direct on 2.75
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After a lot of changes, our bot is now on 450 RPM with 2.75 on 66W blue motors. It works great! Thanks for all your help, everyone.
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Really, however, all of the videos that I have watched all are on the 3.25 inch wheels. But im not saying your wrong.
Right now our brain and pneumatic tanks are REALLY low on our robot
Like our brain is about 3/4 inch off of the ground