Very good diagram of the basic mechanical operation
Forget about clutches, dampers, ignition cut etc. I am going to describe a full power racing shift in a zeroshift box with no torque reduction techniques applied. I refer you to Cheapracer's excellent illustration which demonstrates clearly that both gears are driving simultaneously. Look at figure 2 where the red hub (second gear) which is travelling faster than the blue hub (first gear) has just made contact with its "bullet".
1. At this instant first gear is still doing all the driving since second gear has only just contacted its bullet and is not yet exerting any force.
2. A microsecond later the picture still looks the same. Both bullets are still in contact with their hubs however 2nd gear is now taking some load and the 1st gear load has been reduced by an equivalent amount.
3. The progress described in the previous step continues for a small but finite period. The load on the 2nd gear "bullet" continues to increase while the load on 1st gear correspondingly reduces until . . . .
4. The load on 1st gear finally drops to zero and 2nd gear is doing all the driving. The picture still looks like "2" in Cheapy's illustration but it is about to change.
5. Now that 1st gear is fully "unloaded" the 1st gear hub starts to outrun its bullet and we move to diagram 3 and 4 in Cheapy's illustration.
The key point here is that diagram 2 (both gears driving) is a state that exists for a finite period of time. It has to, because the disengagement of 1st gear relies on the engagement and "overdriving" of the mainshaft by 2nd gear.
NOTE. If the components were infinitely rigid (not possible in the real world) the "overlap" period with both gears driving would be zero. (There would still be no gap in torque transmission).
However grunt you have chosen to ignore the essential modulation of the operation and the damping.
Your description of the operation would produce a graph nothing like the one shown (Zeroshift POWER ON
Your graph would show a propshft torque trace running to the center of the graph with a slight rise dependent on acceleration.
The trace would then drop verticaly at a right angle until it reached the next higher gear torque level.
It would then simply turn through another sharp 90 degrees to horizontal and rise slightly to off the graph.
You are saying there is no break in torque, so the shift overlap would take zero time
If it took any time at all there would still be a GAP
The shift would also be a sudden bang of engagement and not at all smooth like the real zeroshift 'slow' torque reduced shift is.
There are a number of reasons why you cannot simply ignore the control needed on engine torque delivery and the clutch disengagement (slip).
The engine rpm has to be suddenly reduced to the new higher gear level during the shift and within the shift window.
It cannot be achieved in the zero time you state.
The shift cannot be achieved without controlling engine torque, because the road engine shown has a heavy flywheel and clutch with a great deal of rotating inertia.
Even just engine control is insufficient, so the clutch has also to be disengaged (slipped).
You are close in your description to over run shift operation in F1 and similar though.
This is because F1 cars are very light and the flywheel and clutch is also very much lighter than a road cars.
There is also no need for a smooth shift in an F1 box.
Unfortunately a spring detent mechanism such as this one shown in the videos and diagrams would not last for long shifting at very high speed.
AFAIK F1 shift mechanisms are all ratchet types.
Edited by 24gerrard, 11 March 2012 - 16:42.