The gearboxes tend to locked when they are transmiting high torque, in this cases you need to use a clutch for disconnect the gearbox to the trasmission between speed changes.
For eliminate this problems exist a gearbox type which doesn't need clutch for change speeds, the planetary gearboxes.
It uses planetary gears connected between them, for changes speeds you only need lock the corresponding planetary gear without any other mechanism or clutches
This system is very comfortable for secuential gearboxes, but it has a big problem to built it with Lego.
Only exist two more or less planetary gears in Lego and both are big and uncomfortable: a turnable or a extrange Power Miners part
Using the planetary gearbox idea I have designed a version without planetary gears ;). It only uses standard gears (as z12, z16, z16 with clutch, z20...) and some axles and liftarms.
With the same base design you can built differents gearbox types.
Type 1: 3 speeds
- 1st speed: locking the first rotor the gear ratio is x0.8
- 2nd speed: without lock rotors, direct transmission x1
- 3rd speed: locking second rotor -> x1.6
Of course you can ger others gear ratio changing some gears
Type 2: Forward, neutral and reverse
Looks almost like the 3-speed type, but is very different.
- Neutral, without locking rotors
- Reverse, locking the first rotor
- Forward locking the second rotor
You can join some of this types to built a big gearbox with more speeds, reverse and neutral. now some examples.
- 3 speeds in each direction and neutral
- 6 speeds
- 6 speeds in each direction and neutral
Try to make you onw configuration!!!
Also here you can see a video explaining how the gearbox works
You can see more pictures here:
And download instructions step by step for both in the INSTRUCTIONS page, enter and access to the Download folder
Thanks for reading!!!