List of Non-Compound Gear Ratios and Output RPM's

Getting the right speed for a drivetrain can be pretty tricky, so I made a list of all the possible output rpms that could be achieved with only two gears. This includes the 24 and 48 tooth gears available in the vExplorer kit and from VEX IQ, and the custom 1200 and 3600rpm cartridges that VEXU teams are able to make.


Would be nice if we got new 24, 48 and 72 tooth gears. We’ve been stuck with 1:3:5:7 gear ratios for pretty much forever, unless you want to spend $100 on a 2007 ebay set for 2 parts.


Well, I think the main reason we are stuck with there ratios is fitment issues, the 12,36,60,84 fit perfectly into the hole spaces the 1/2" spaces they give you. Any smaller and you have to custom make things, any bigger and it won’t be worth making it since people won’t want them as much.

24 and 48 tooth gears exist, you just need to buy an entire vexplorer set for those parts. If Vex sold those parts individually then I would probably use them on my robot.


why would they stop making them like they do the rest of the gears?

I’m wondering the same thing. Probably since they aren’t on the same holeset as the other gears, but Vex sells 1/4" pitch bearings to make them usable on the same line of holes.

I recently got my hands on 3 vexplorer kits. I did not find any 24 tooth gears. The pinions in the lift section are 12tooth gears.

The good news is that 48 teeth gears mesh perfectly with the standard gears but do require custom spacing or 1/4 pitch spacing. I did explore the possibility of using pythagorean irrational spacing on 5-wides to approximate 1/4 pitch spacing. The closest results were the 2-3-3.6055 triangle and the 2-4-4.472 triangles (4.472 is very close to 4.5). You would have to file or drill out the holes slightly to utilize the spacing. It is probably more effective to just space a 2nd c-channel off the first one and adjust the distance to a custom length.

These results indicate that VEX has decided to not make 48teeth gears available because the 48 teeth gear has no good gears to mesh with other than itself. In addition, from Chris_3553B’s spreadsheet, they do not appear to generate any useful rpms not approximatable from conventional means. But it should be noted that they are useful for their small size and spacing which is why they were first used in the vexplorer kits.

I did not find any 24teeth gears, but if they do exist. Please share pictures.

On a side note: can someone try modifying the 24 teeth worm gears into spur gears and share the results?


Aren’t the 24T Gears in the claw?

I did not check that but it is a fair possibility. From images online, the Vexplorer claw appears to be identical to the standard green one so I did not bother to check. The pinion in the claw iirc was 12 tooth. There are 2 custom gears fused with the claw mechanism but I am not sure about the teeth count on those. I did not consider using those gears because I would have to snip off the arm plastic and the gears would be missing a few teeth.

Like the OP said, IQ has a 24 and 48 tooth gear kit.

I have kids that use the odd and even multiples of 12 together by simply using the offset holes. The teeth mesh well enough for IQ, but I’m not sure how it would work for VRC.


The worm (wheel) gears in the advanced motion kit (Advanced Mechanics and Motion Kit - VEX Robotics) are 24-tooth gears. Although they have a slight helix to mate with the worms, they are close enough to the regular spur gears to mate. We’ve had a team in years past use these successfully on a robot design, in a low-strength application.

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Huh, that is good to know. I’ve never personally owned a vexplorer kit but from talking to others online I knew they were a source of 48T gears but I must have just assumed that they also had 24T gears. I’ll update the doc to show that. For using 48T gears in VRC I’d personally use lexan so that you can drill or cnc the holes at exactly the right spacing.


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