I’m coming to the VEX Community to try and help out my middle school team. They are trying to determine how to rig up their 4 motor base drive. And yes, they will be staying with 4 motors. They started out with HS motors on a 1:1 ratio. This all worked fine but they would like more speed. They geared the 4 HS motors at 2:1 and picked up speed but they started tripping and stalled during competitions. Their scissor lift may be a little heavy. So their question now is would they benefit from going to 4 Torque motors geared at 2:1? Would they pick up quickness with less chance of stalling?
High-Speed gears are 1.6:1, so HS geared at 2:1 would be 3.2:1
Torque geared at 2:1 would be 2:1 (obviously) This would be a little faster than direct HS, and have a little lower torque. If it doesn’t stall at HS direct, that I would fathom that it would likely won’t for Torque 2:1
They are actually 1:1.6
Turbo 1:1 would be a good in between at 2.4:1, and it would be easy to set up.
You would probably be fine with a 4 motor torque then 1:1
They might still stall, though…
It would at least be better then high speed 2:1. Also the external gearing in that setup would add extra friction the 1:1 turbo wouldn’t have.
Guys, you cant put a scissor lift on a four motor turbo drive. Even high speed will probably stall rather easily. I would recommend starting with torque.
@Bryan R is absolutely right, you cant have a 4 turbo drive, I’ve run it a couple times on very light bots and it still stalled in some games. an average DR4B is fine with 1:1 HS, but a heavier scissor will probably require 1:1 torque to be reliable. i generally wouldn’t recommend an external ratio, but if you do plan on keeping that 2:1 ratio, you almost definitely need to use torque, and even then it would probably stall. use this chart to compare different drive ratios. https://image.ibb.co/fLie9G/image.png
Thanks for all of the replies guys. Due to motor and wheel placement they chain motor to wheel so they will have the extra friction even if they go 1:1. They ran 1:1 with HS motors for three tournaments and never had stall problems. Sounds like the 2:1 ratio with the torque motors would give a small increase in speed over the 1:1 HS motors so maybe they will try that.
It seems they may also have had a problem with tripping the cortex as they had all four motors in ports 1-5. They are also going to separate 2 motors off to ports 6-10.
Yes splitting the pull of the motors between twon bridges is a good idea. Another drive setup i use fro m time to time is a 1.5-1(18t-12t) sprocket ratio. This is great cause then i can easliy swope out drive speeds between matches and skills. The torque setting would provide 150 rpm which is lower than 1:1 high speed but high speeds on this ratio give turbo speed with more internal torque.
We use a 4 motor HS 1:1 set up for our base and we’ve had no problems with it burning out during competition; although, it ends up burning out after strenuous work after 8-10 minutes.
They should switch to torque geared motors and 5" wheels, if they can fit.
i suggest keeping the four motor HS drive. improve speed on everything else and lighten weight of the bot.
- getting rid of unnecessary metal
- use all aluminum
- design lighter and more effective systems