Heyo…
We are building our drivetrain and we are planning to use this gear ratio:
We are going to use 3.25 wheels and feel like the speed will be decent with green cartridges.
Is this ratio viable?
Thanks!
- Henry 344E
We are going to use 3.25 wheels and feel like the speed will be decent with green cartridges.
Is this ratio viable?
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This is a very viable speed of 333 rpm on 3.25 inch wheels. However, if you have access to blue cartriges, using them with a 36:60 ratio will allow for pretty easy traversel of the barrier which is an advantage. Nonetheless, good job doing your homework and picking a gear ratio that will work well!
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This is certainly okay, although in general, it’s better to gear down than gear up. If you have blue cartridges, I would recommend reversing your gearing for 360 RPM. If you only have green, this is one of the best gearings you’ll be able to have for your drive. See the Catalogue of Drive Gearings for more information regarding drivetrain gear ratios.
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I used that gear ratio last year for spin up, and felt it was fast enough, but lacking in torque for push fights and trapping (both the one trapping and being trapped). So it would be good for speed, but I recommend an anti-static wheel in the middle so you cant get bullied as easily.
That’s the plan, we are using an antistatic so we cant get pushed.
Good to know, thanks! Our mentor isn’t allowing us to use blue carts for our drive unfortunately…
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That catalogue was definitely part of our research. Thanks for your reply!
What’s your mentor’s reasoning? Why can’t you use them?
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We don’t have enough of them for all of our teams. (plus we probably don’t even have enough for a drivetrain…)
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That’s unfortunate but you can get by without them. There are good ratios with 200 even if people don’t usually like to use them
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I feel for you @bantha cuz I just had to put in a $350 order from vex for stuff like blue cartriges, 72T gears, and 5.5W motors because my school refused to buy us more parts and it was to short notice to do fundraising. 
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This is probably the best ratio imo for 200 rpm motors. But if you’re stuck with only 200 rpm motors and have 5.5w motors you might as well make a 5 motor drive to get more out of this gearing.
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Yeah we don’t have 5.5’s unfortunately.
I don’t mean to bump this discussion again but I had another follow-up question.
We are changing our robot up to allow us to add two more motors to our drivetrain to make it 66w, and were trying to figure out how to mount the motors. Would it be reasonable to stack another 60t gear on one of the main ones and mount it that way? (see original post)
Thanks in advance!
- Henry 344E
Yes… it could work…
However, that is a little high to mount a drivetrain motor. Do what you have to do, but if your robot has been wheelieing, then this will only make it worse.
Also...
Happy Valentine’s Day! (Almost)
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We were probably going to do it on the front side of the drivetrain so no wheelie. What alternative(s) would you recommend?
You can try doing this:
However, don’t cantilever the axle like I did (have it supported on the other end too). It leads to a lot of mesh problems, especially when changing directions quickly.
It will make your drivetrain pods quite a bit wider though.
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from 606X drivetrain explanation
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Do you have more pictures of this? We might end up doing this in our drivetrain. In my cad software I can’t find a way to get 36 tooth gears to stack
I would recommend doing this. If I am not wrong, this is your plan, right?
(This image is taken from the Catalogue of Drive Gearings, as mentioned by another user in this thread).
I would recommend doing it like this in order to get an 8 wheel drive. Not only does this allow you to mount another drivetrain motor on each side, 8 wheels reduces the amount of ground pressure per wheel, meaning your robot sinks into the tiles less and moves across the field more easily. In addition to this, there are more points of contact on the ground, giving more traction to push other robots, as well as increased stability from longer length.
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