pic: One for the middle
 

Re: pic: One for the middle
 

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?

Re: pic: One for the middle
 

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.

Re: pic: One for the middle
 

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.

Re: pic: One for the middle
 

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.