pic: One for the middle

As this year’s game progressed we talked about advantages of having a shift on the fly 3 speed transmission. Having a low gear in the 5fps range, a middle gear in the 10fps range to pick and place game pieces and a high gear in the 15-17fps range to transverse the field upshifting along the way. A combination of AndyMark, iR3, WestCoast Products and VEXpro parts are shown in the rendering. Shifting is accomplished using two dog gears, one on output shaft toggling between low and middle output gears and one on the counter shaft toggling between middle and high input gears.

Technically you have designed a four speed (2 speed on one shaft x 2 speed on the other = 4 possible ratio combinations), unless one of your shifting stages is a 1:1 ratio.

Edit: Looking closer at the image (instead of relying on the description) I can see what you did to make it a 3 speed. Took me a minute to follow the power path from input to output. I still don’t see how you get the power routed through the first layshaft though. It appears as though the selection of the input cluster is irrelevant as the center gear is tied to the shaft (AM style) without that cluster selected how do you transfer power to the single input side of the gearbox?

In low, output shaft dog gear is engaged into 45 tooth output gear and countershaft dog gear is engaged into a 28 tooth input gear. In middle, output shaft dog gear engages into 35 tooth output gear. In high, countershaft dog gear engages into 35 tooth input gear. 3 speeds in total.

I see it now. The possibility of the 4th gear is eliminated by a possible jam though. 35 tooth input gear and 45 tooth output gear selected at the same time splitting the power on the input shaft and supplying it to two fixed sources on the output shaft at two differing ratios.

Looks good though. I like it, I need to get back into tinkering for FIRST purposes. I do this stuff at work all day but I haven’t experimented in a while.

With proper software to disable the drive motors, this jam could serve as a reasonable mechanical brake. Could be useful for certain situations like the bridges in 2012.