I would like to know what peoples opinions were towards transmissions are. What kind do you use? Are they worth the trouble? Do they cause problems? And are they really that useful during the competition.

Well we personaly really like that a transmission allows use to go both fast but still have the power to push.

We use a two speed transmission on our competition robot and it works very well and has gotten us out of some sticky situations.

The only thing is though, if you dont build it well it can cause more problems then it is worth. But I would say that a well built transmission is very usefull.

Exothermic 10D

I have build a couple of 3 speeds. I model them after car tranmissions in the sense that they have an input up front with the motors and a clutch and the output in the back that needs a differential or 90* bevel in the back. I have never had one work very well. I was able to drive it and get it into 2nd but it took a long time to pull the clutch and shift. By the time I got from 2nd into 3rd I would be out of momentum and would have to shift into 1st. Maybe once the seasons over I will perfect one and get it to work if I have time. If you can get one to work really nice I would love to see it.

The pushing power that’s derived from transmissions seems to be less advantageous than some people think. The best scoring robots won’t give pushing robots the time to switch to torque mode and get in position to push them before they score their desired objects. Similarly, a defensive robot doesn’t need high torque to be effective. Smart positioning and a quick drive train can cut off any route that the opponent attempts to take. That’s my view on it at least. Transmissions are cool engineering/innovation wise, especially using the materials provided by VEX, but they may not be as effective in such a relatively cramped field space.

I absolutely agree with everything you have just said, this has been my view on transmissions for quite some time. I believe having four 393 at highspeed is the perfect speed/torque for a robot that does not weigh too much (10-15 pounds). My team use two have four 269 + two 393 at a 2:1 ratio, we found that it worked excellently in qualifying matches where there were only two minute drive times. Once we got to the elimination rounds, the small time between matches gave our motors little time to cool down and it would heat up. Two 269’s are not that much powerful than 1 393.

Bottom line. I find that a highspeed 393 has the perfect speed/ratio for an efficiency robot.

I have seen quite a few robots this year with a working transmission. Does anyone have a close up video on a well built gateway transmission we could look at?

Here is a 3 speed my old team built before I joined.

Game was Quad Quandary.

  • Andrew

I have some 75MHz RC transmitters for PIC cpus; the usual trouble is multiple transmissions using the same crystal frequency, and then your robot does what someone else wants.

The vexnet system reportedly uses a subset of 802.11 transmission technology.
The usual trouble in our local school environments is that the school IT infrastructure will block the transmission, but only the second time you turn it on, leading to red blinky lights. The solution is to use the Vex utility to get the MacID of all your vexnet usb keys, and put them in the IT infrastructure ‘whitelist’ of allowed users.

I’ve heard that some people are bothered intensely by transmissions; when wearing an aluminum foil hat is not enough to stop them, they have to move to an isolated place without electricity.

I find it much easier to use transmissions during competition; otherwise you have to use tethered mode, and the tether wires usual get tangled.

As one of the first teams to use a Transmission on a competition bot we have tweeked it enough to swich very fast! i do belive that it is worth the trouble. come by our pits at worlds to check it out!:slight_smile: