Today I'd like to show you a 6-speed sequential type LEGO gearbox, made by YT user haRtV70R, that I've found only a few weeks ago.
He refers to it also as a Tiptronic transmission but this term is often used erroneously, hence I'd simply call it a manual sequential transmission. The Tiptronic term refers to torque converter automatic transmissions that incorporate a manual upshift/downshift feature, which I do not think to be the case here, despite we can't see any inner details from this design.
Although the internal gearbox design is not disclosed in the video, I find the overall solution quite interesting.
The video shows the sequential gearbox being exercised while the power is transmitted into this, by a V8 pneumatic engine inspired on LPE Power V8 Engine. Nice decoration added with the yellow panels on the top, though.
If you have the interest, you may also find at other videos from the same author, how his V8 LPE performs [1, 2].
Some weeks later, haRtV70R also included a set of modifications to add a Reverse, turning into a '6-speed +N +R' sequential gearbox type. See the demo on the video below. Here with the input shaft, driven by a PF M-motor instead.
The usage of one NXT servo to precisely control the gearbox up/down shifting, is indeed the cornerstone that makes all the difference to this electrically controlled sequential gearbox.
The motor looks very well integrated into the gearbox design! Unfortunately its size is rather huge - Definitely we need something smaller for the same functionality, with less torque probably as it is not really needed here.