LEGO 2: Sariel.Pl » Speed Automatic Gearbox

Step-by-step instruction and a two drive motors variant included. Since the power-to-weight ratio of each vehicle decides how much points it gets, it is favourable to reduce this power to minimum.

Lego 2 Speed Gearbox

This is where gearboxes come in handy – they allow to use less motors, or less powerful motors, increasing gear reduction when needed, and decreasing it when less torque is needed. The loads exerted on vehicles’ drivetrains in our races are so high that it’s very difficult to use a gearbox with driving rings. In most cases, it results either in the driving rings disengaging under load, or in mechanical damage to them. Therefore it’s a common practice to use simple linear gearboxes, with as few gears as possible, as most vehicles can do very well with just a 2-speed gearbox.The need for reducing amount of gears to minimum resulted in integrating the drive motors into the moving parts of the gearboxes, so that the motors slide as the gears are changed. Fiat’s gearbox has failed during the race, but it has given me the opportunity to observe exactly what are the causes of its malfunction. Based on this experience, the new gearbox has been reinforced in all the crucial spots and is practically immune to mechanical damage, while still being relatively compact and simple.

I have provided schemes, views from various angles and a full instruction for the gearbox, as well as a scheme and views of a version using two drive motors instead one. Fiat have shown that it’s best to make it part of the chassis close to the gearbox, that part of the gearbox itself. Still, building such a mechanism should be fairly simple, as all it has to do is to slide the central bracing a single stud back and forth, and keep it in place.

Lego Technic Ultra Compact 2 Speed Gearbox + Instructions Lego Technic Mastery

The most compact Studless Lego Technic 2 Speed Gearbox I could design to this day !

I followed the building style of my last 4 …

The mini linear actuators are one of the many options that can be considered here. The gray frame that braces the gearbox should be fixed and not moving – instead, the gearbox moves through it.

I have no idea what is this “ground level” question about. The gearbox is too simple for the extra torque to get wasted.

I build a mechanism like you did with humvee?

I was having some trouble trying to explain exactly what the problem was. Thanks though, your always a big help whenever i have problems building. The initial problem is with my drive shaft because it wont allow me to push forward into the next gear. If i connect the gearbox to the frame of my truck it wont switch gears because it just pushes the frame and starts to grind gears. However, changing the speed should be made fast, in order to prevent the gears from stucking. Maybe a fast geared small actuator can do this?

If you put bushes there, the gearbox won’t have space to slide. But it’s still good to keep the gears meshed properly, or they may be more prone to mechanical damage.

I know that these 20 and 12 toothe gears tend to cause friction when given a one-stud wide space like here.

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Build Lego Technic Compact Speed Gearbox / Instructions

Instagram: Build this gearbox for your own lego car!

Only 32 pieces needed!

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