We have seen 4wd and 6wd
And the results have been more favored towards the 4wd because the middle wheels would “rock” the robot even more vigorously when going over the bump
But has anyone tried small wheels in the middle?
how were the results?
(something like this)
Thats the configuration my team is currently using.
We didn’t like the bounce of a true 6wd at all and the instability while going over the bump.
Unsure how much the middle wheel helps, didn’t do much testing with a 4wd without the middle wheel. Will see if I can remove it and compare performance sometime within the next week. (fieldless right now)
My B team had this configuration. It went over the bump quite well, though they eventually switched to only four wheels. I think they had it geared up to compensate for the 2.75 inch radius
we geared it the same as the 4" wheels because during normal gameplay, the small wheels dont touch the ground so it doesnt affect anything
but when its on the bump, it helps drive it over. And the off-set of the ratios only occur in a short time frame and distance that it should be a negligible difference.
I had this setup for the early part of this season. I found that the robot was capable of getting over the bump as long as the lift moved to shift the center of gravity, but that could have been easily solved if the middle wheel had been chained to one of the driven wheels. In the end, I ended up switching to a true 4 wheel drive configuration with no middle wheel and mounted the wheels on pillow bearings in order to get the clearance needed to get over the bump. I have found the current setup much more effective.
Our middle school team uses this configuration. It works pretty well, and allows them to drive over the bump without an elevated chassis, but I think an elevated 4-wheel drive gets over faster and more cleanly. Sometimes, if their robot stops part of the way across the bump, it can be very difficult for it to get off of the bump.
Any particular reason the thread title refers to Gateway?
My team uses the middle wheel configuration.
It works pretty good but the 4wd is definitely superior.
Here and here are pictures.
This design is the best 6wd in my opinion because the robot doesn’t rock a whole lot (at least with the setup I have) so I don’t have to worry about tipping.
Overall, this drivetrain layout is best if you are looking to save space vertically (because the 4wd needs complete clearance). This save about an inch of height. However, if space vertical isn’t an issue, then go with a 4wd.
My team will be switching to a 4wd.
Did that. Posted on the website.
The middle wheel doesn’t help. It actually hinders you compared to just 4 wheels. Pillow block them, and you’re good.
Yes, in this setup, the middle wheels is indeed chained to both the 4" wheels
4 hrs of sleep took its toll 
Indeed, this was why we choose this design
we need the extra vertical space
this should be better than just 4" 4WD with no pillow blocks
The general vibe I’m getting from this thread is that this not the worst drivetrain configuration however there are better alternatives. An elevated drive is a much better option than this middle wheel. Even if pillow blocks aren’t a possibility for you, use some small pieces of C-channel to mount your wheels a bit lower than the rest of your drive. Is it really impossible to tweak your design to accommodate that loss in vertical space?
This drive configuration should be able to go over the bump:
https://fbcdn-sphotos-f-a.akamaihd.net/hphotos-ak-frc3/425460_1908586492362_2130541033_n.jpg
LOL, man first look, that was really funny. The stuff you guys prototype eh?
Yeah and the other teams were wondering where all the wheels in the classroom went…
Lol, wow, what is it? It seems like it could run over anything, the isolation zone barriers, and robots.
Not sure what the builder was intending when he built this, but my guess would be he wanted to overcome anyone and anything in his way.
Murdo is this your robot? or a team your mentoring
its a bot made at gladstone
Ik, the original post.
Our team used to have a smaller wheel in the middle, but we’ve since migrated over to 4 wheel drive. It gets over the bump just fine, and the wheel just seems extraneous after a while
My teams current design has four wheels with the back motors attached directly to the back wheels and the front wheels chained (1:1) to the front wheels with the motors right next to the back wheel motors. I am hoping to put tank treads on the chain that spans between the front motors and the front wheels. This will, hopefully, help it over the bump to some degree.
