gears are engaged yes, but the dogs driving the gears aren'tautogyro wrote:Two gears are NOT delivering torque at the same time, even though companies like zero shift would like you to think so.
In a constant mesh lay shaft gear box, ALL gears are engaged at the same time by virtue of the design.
So the term engaged is misleading.
It is certain components of the shift over lap mechanism that are engaged at the same time during a shift.
Engine torque cannot be delivered to the rear wheels through two gears at once.
in the good old H dogbox it was impossible to enable 2 dogs at once - have the transmission be in 1st and 2nd gear at the same time, because if that was the case - something would go awfully wrong and you would finds bits and pieces of something that used to be a gear or a dog
that being said - now imagine that the recess in the gear where the dog ring fits in is a bit larger than the width of the dog - meaning, while in an engaged position - you could rotate the gear against the dog for a few degrees back and forth (this is what one poster before me referred to - limited time to disengage the previous "gear")
and now the "magic" of the seamless shifting - you have your 1st gear engaged - and while it is engaged - you also engage 2nd gear - and as soon as the 2nd gear starts to transfer the torque of the motor the wheels, the 1st gear dog no longer is transmitting any torque and the dog can now easily be (and MUST be) disengaged fast - and all thanks the larger recess in the gear for the dog teeth previously explained
so the 2 gears are never transferring the torque at the same time
and the "blip" or intentional misfiring of the engine during this seamless shift is to lower the stress on the whole thing, make the parts last longer
now if you understand all this, you would never ever say that shifting during acceleration was better or faster with the good old H pattern dogbox, it simply is not true, because the mechanical design of the gearbox prevents true continuous transfer of torque from engine to wheels
shifting under braking is different thing, but one could argue that with precise enough control you could achieve the seamlessness there too - something nearly impossible to do manually from the drivers seat - which is a bad thing if you want to see just pure driver competition on the track, but then there are hundreds of engineers working behind the drivers for the whole thing to go faster - so - while old school dogbox was good skill test - now days you simply have to appreciate the engineering that goes into the computer controlled shifting / braking / harvesting as well, and this is where Mercedes have really excelled
