dontworryaboutit:
To answer your last question first:
Robots without transmissions have been winning VEX games for years, and I don’t think that is likely to change.
In 95% of matches in VEX Sack Attack, having a transmission will not have a decisive advantage over single-speed drives. However, there are cases where you are being blocked and cannot push past the other robot where a two-speed drive can save the match. But for the most part, transmissions are just to show off (because they’re cool).
If I were going to make a transmission to put on a competition robot, it would have a “normal” speed that you would use 95% of the time. Then there would be a high-torque speed in case you were getting blocked or had to push your way through some sacks. The speed switcher would be a single differential per side of the drive base that locks one output or the other using pneumatics. It is very light and only adds a few gears to the drive train (albeit bevel gears).
Hope that helps
Personally, I do not want to use transmissions this year
NissanskylineN1:
Well, what you can do is try to design a transmission involving the least amount of gears, due to friction. That will lower heat.
As for our team’s robot, I think we will try to come up with an effective gear ration and make our bot single speed. We might add in a torque gear with a simple transmission.
I’m currently designing a speed-shifter that only adds two axles between the motor the wheel, so the friction should be minimal. All of the planetary gear sets that people are building add a lot of hassle and resistance to the shifting operation. We’re looking at 2:3 for speed and then 3:2 for torque as our two ratios (on Mecanums).