Funny thing, first gear is still going 8000 rpm, even though the bullet ring (and the engine) is suddenly going 4000 rpm, so first gear immediately outruns the blue bullets, releasing their interlocking grasp. At this point the blue bullets will pop over to second gear, either because of the spring pulling on them from the bullet ring or because the next first-gear dog has come swinging around and smacked it from behind (figure 3).
Which brings up another clever little detail about these Zeroshift bullets, they're angled on the other side so a dog hitting them from behind will push them away from the gear.
Wow, we just shifted from first to second gear at full throttle without lifting and with no interruption of power, and we did it with a nearly conventional dog box with some very clever dog rings. Step back for a minute, revel in the brilliant simplicity of this design. Have a beer. Take an aspirin.
Why you can't have one yetIs your head done throbbing yet? Let's think about why you don't have this gearbox in your car yet.1: They just thought of it a few years ago It's youth that's the only thing keeping Zeroshift from selling you this technology in a racing gearbox right now. There are bigger fish to fry than your racecar, though. The Zeroshift design has the potential to offer the same ambidextrous performance as the VW/Getrag DSG, putting real, usable manual shifting and seamless slushbox performance into one transmission. And without the DSG's more expensive multi-plate clutches and concentric input shafts, it should be much cheaper to build.
Ah, but making it civilized brings up problems two and three.
2: Shift shockThe gear ratios I made up were a little unrealistic, so the engine won't go from 8000 to 4000 rpm in an instant, but it probably will go from 8000 to 6000. Dumping 2000 rpm worth of engine inertia into the drivetrain in one sudden jolt will cause, well, a sudden jolt. No big deal if you're drag racing. Very big deal if you're trying to sell a car with this transmission to your Great Aunt Ethel.
Same thing happens when you downshift. Say you're trail braking into a corner at 6000 rpm and you bang down a gear. Instantly the engine has to be going 8000 rpm, and the power to spin it up has to come from the drive wheels. The car lurches, the drive tires bark in protest and you go spinning into the weeds.
So Zeroshift has to work on some way to smooth this shifting thing out. It could be some sort of slipper clutch. It could be some connection to the engine management that cuts power during upshifts or blips the throttle slightly during downshifts. Or something else entirely. They're smart, they'll figure it out.
3: Shifting the rest of the timeUpshifting under power works great and downshifting during engine braking works great, but what if you mash the gas first and then decide to downshift? This will happen with a manual if you're not planning well, and it's standard operating procedure on an automatic, which doesn't know you need to downshift until you mash the gas.
If you're in second gear at full throttle, the red bullets will be locked into second gear. Shift down to first and the blue bullets will try to grab the dogs, but they'll hit the back of the bullet, the side that's cut so it gets kicked away from the dog, and you'll stay in second gear.
Downshifting here will require a brief lift off the throttle to let the red bullet disengage second gear. Zeroshift could program the ECU to cut power for a fraction of a second to pull this off, but it isn't going to happen with the mechanical simplicity of the full-throttle upshift.