Tamas Juhasz

Impressive project, I like the function switching mechanism. I wonder that nobody thought about string operated actuators: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=534220 Extremely strong, small, can be built in different lengths. Except for the string it's 100% Lego.

No, this topic isn't for mini building. If it were, the title would be "mini versions of Lego technic sets". Arvo's cars are fantastic, but others: they have no motorized or working functions. They are more models, mine (8868) more focuses on the autentic functions (compressor, pneumatic valve, steering - similar like 8868's solutions) When I wrote about the planned mini set mocs, I thought about mini models with some working functions, which are similar, like in the original technic sets.

Boxerlego has right, a reverse gear is unnecessary in a gearbox because of the electric drive motor. Yes, with reliable control you can do 3 gears with the PF servo. The speed controller is very unstable and isn't reliable for shifting. A servo operated gearbox is a very simple and easy to build construction. You have to build a 4 speed gearbox (for example this: http://www.brickshelf.com/cgi-bin/gallery.cgi?i=2513289 ) with 16t clutch gears and synchronizing rings, and put two servos to each side. The servos's 0 position is neutral:http://www.brickshelf.com/gallery/mbmc137/pictures-videos/servo-gearbox.jpg The 4 gears on each side aren't necessary, I just had no space for the servos sideways. (sorry sor the bad picture, but it's built in to a "secret" project )

This gearbox isn't 100% reliable. Works well with fresh batteries, but it's not for high torque. Why this isn't good for you?: http://www.brickshel...ry.cgi?f=518300 - handles high torque, easy to use and reliable. I try to share my gearbox (transmission) building experiences: There is two part of an RC gearbox: 1. The gearbox itself. Can be linear, synchronized, etc. This is the easier part to make, you can find a lot of gearboxes on brickshelf. 2. A shifting mechanism. This is the essence. If you use a linear actuator for a linear gearbox, then how can you know, the gears's teeth are exactly an precisely overlapped? Every time you watch it? If the teeth ar overlapped 60% instead of 100%, then they are more able to deform, then it can handle less torque. This is the problem with continous control. You don't know exactly, how the gears are connected to each other. You hear that the new gear is in, then it's ok. But sometimes it isn't. That's why I made with lot of experiments the definite controlled gearboxes ( http://www.brickshel...ry.cgi?f=518300 ). You can control them in 100% darkness. If you push one lever up, that always do the same gear change. In a linear control, you have to know which is the current gear, to change it. For example, from 3 to 2 or from 4 to 2. If you want to shift to 2, then you have to know which is the current gear, to know how much shifting you need to do. Control mechanism is the most important. You can do a definite controlled 4 speed gearbox also with two PF servo motors. I tried out, works well. Another thing: When two gears are close to each other in a linear gearbox, then it's able to scratch a lot during shifting under load. The sliding gear is connected to two other gear at the same time.

I made last year a 4 speed one, it's pretty strong and reliable: http://www.brickshel...ry.cgi?f=518300 http://www.eurobrick...7000&hl=gearbox You can see the controller in the last part of the topic. Needs two PF remote controllers, this is the better controller setup: http://www.brickshel...y.cgi?i=5742902 (better than this: http://www.brickshel...y.cgi?i=5698446 ) You just pull the lever, and the gearbox does it's job. Doesn't matter, which is the current gear in, you can shift also from fourth to second.

Thanks, but what about with this in my moc topic? As you wrote, it's not automatic. It's not a challenge to make a motorized valve.

Very clewer idea with only a single switch. Your video is also well edited and clear to understand. I associated to the 8868's B model, that is similar (and the best B model all time).

Last day I realized something: when I use this ( http://www.brickshel...ry.cgi?f=534632 ) autovalve with a new/tight pneumatic switch, it's able to click instead of moving the gear with the worm gear. It's no problem with loose pneu switches, but I want to make it reliable for every setup, so I rebuilt it into a V2 autovalve, based also on worm gear conception: Now it's 100% reliable, can't get wrong. The second worm gear holds up the pneu switch's lever. The pump isn't in the pictures, but it's easy to build in.

Yes, it's true. But a curve will be interesting to see the maximum rpm with the constant torque. How much is that rpm limit? It depends on air flow and pressure (and the limit of Lego parts). Power has a maximum value, so rpm also has to be.

Even clutches are many times unnecessary, automatic clutch can be made from a normal clutch connected with the gearbox operating mechanism. When you shift gear, the clutch works (not easy to made). Friction disc clutches are big, I don't recommend you in a single 4x4 car. But the gear shifting would be better with clutch of course. Your choice, if you want a clutch, then add it. But when there isn't much torque in the drive chain, and you dont want to shift gear when there is load on the gearbox, then clutch doesn't add too much plus to your construction, "only" will be the car more realistic. Centrifugal clutches need a LOT OF rpm. Even with buggy motor, you can produce a small amount of torque to transmit. It can be made with Lego technic, but a serious centrifugal clutch would be also pretty big. You have to stop the driving motor during gear change to have sence of the clutch. But maybe it's good for you, I never tried this type of clutch.

There is two friction clutch I know about: 1. http://www.brickshelf.com/cgi-bin/gallery.cgi?f=532696 2. http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5059300

It's good to be curious, but it took me 3 seconds with google: http://en.wikipedia.org/wiki/Power_take-off

If I remember well, it's a freewheel system, in one direction it allows torque to transmit, in other rotation direction isn't. An automatic clutch works like a car clutch, in both direction.@Dans lego: What type of automatic clutch do you think about? Like a real car clutch with friction discs, like a 16 tooth clucth gear (for example in Sheepo's Land Rover), or like a freewheel? Clutch has many types.

The driving axle is a very clewer solution. How do the chain links connect to the main driving axle in the engine? There is a "flat" surface of the axle. So all power is transmitted through 1s wide Lego chains? Anyway, Nicjasn has right, if there is enough from something (even from a little thing), you can move tons. LPEs are pretty strong, and 8 bar pressure is serious. Beside torque, rpm is also important. Power is torque*rpm (rad/s), so at maximal torque, how much rpm can produce this engine? Is there available an rpm-torque diagram (I'm an engineer ) ? That would be interesting, would tell "all" about the engine.

You didn't get it. There would be absolutely no problem, if they wouldn't advertise it as "life sized car made entirely out of Lego". Where do you see in the BBC article written, it has a metal frame/metal loaded parts? It's a normal car, covered with Lego and driven by an LPE. Why should be someone jealousy? Rather than that, people can be feel scammed. Every people who reads the article, think, it's full Lego. That's the problem. If it were a big ship (like VFracingteam's mocs), or a huge moc car fully made of Lego, Lego technic, then I will happily congratulate them. As I said before, the 256 piston engine is genial, but that's all in this car which is a Lego technic construction. This forum is for conversations, pros and contras. Permanent gratulation for everything wouldn't be so interesting. Lipko and Meatman wrote the essence: "Well, Burf would be a bit rightfully jealous. And all other awesome builders who don't have the chance to get some attention outside of the tiny Technic community, because their creations are not "life sized", "1 ton", etc." "They are promoting this as a "Car built entirely of Lego" and that just isn't the truth. It has nothing to do with being jealous, more so with being deceptive on their part and they are being called out on it. You can't come along and advertise something and then when people start asking questions you make excuses and get upset."

The most unabashed LIE in their webpage: "Working car made entirely out of lego, powered by air & reaching dizzying speeds of 30km/h" "entirely" There would be no problem, if they would describe this as a lego body and an LPE in a car frame, but they don't do this. Ridiculous.

In TLBC: The engine is awesome, but that's all. I even don't understand, why consider Lego builders great this car, if it's NOT a lego creation. Metal structure and metal loaded parts?? Then no sense of all. The thruth is, you can make a similar sized vehicle from 100% Lego parts, that would be great. But for those, a lot of engineering work would be needed. Wheels are one of the hardest parts only from Lego, but not impossible. Thinking outside of the box helps a lot. My only problem is with such a big project that I don't have tons of parts and time. Many people will consider this a LEGO car which works, and life sized, even it's strongly a mixture of a metal car and Lego body & engine. They are so "humble" they call their own project superawesome: http://www.superawes...ject.com/about/

@Lipko: I'm currently building a mobile crane with similar, big boom. There is no way to use pneumatic. Pneumatic cylinders looking out ridiculous in such large booms. I use this, and I strongly recommend something similar, string operated cylinder: http://www.brickshel...ry.cgi?f=534220 With a strong string and this working method, there is no stronger cylinder, which looks good. (You can even decrease the string force with using reduction inside the cylinder.)

Thanks! I don't know yet exactly, which flagships will be made, but likely the followings: 8479, 8862, 8466, 8421, 8258 (extremely likely), 8110 (with the new 49,5x20 "small Unimog wheel"), maybe 8285.

Thanks all! I'm planning to make more flagships in this size, the only problem I have limited time nowadays. 8868 is also one of my favourite sets too. It's the perfect '90s technic set, and a very good part package.

Hello! Some years ago I made a miniature version of the 8868 classic technic set. It's a 1:2 scale model of the original set. The pictures could be better, but I made them in 2010, back then I didn't care much about lights and background. Original: http://www.brickshel...y.cgi?i=3727866 My version: Folder: http://www.brickshel...ry.cgi?f=429085 I tried to make a model also of the V6 engine: Like the original, it has a pneumatic compressor: You can control the small pneumatic cylinder which can raise/lower the claw arm in the back with this pneumatic switch. In the original 8868, this switch is placed similar. (there are sticker copys about the original's stickers to show the arm's positions) You can steer it with HOG, and a micromotor drives the vehicle (unfortunately back then I used a cutted piece in the drive shaft, but it can be made with regular Lego pieces - I"m planning to make this mini 8868 again in a better way) Of course, it has cables for powering the compressor's 71427 motor and for the micromotor. The claw arm can be only raised, and a small rubber band is responsible for the backward movement: With the small 8t gear in the right side of the cabin you can rotate the upper structure. This is the mechanism to make it: http://www.brickshel...y.cgi?i=4453741 Video:

My fault, I don't have time to read all the comments, in this case there is no problem. But a linear motion doesn't help to solve the basic problem/idea of this topic. So I understand now, you wanted to show us a technic for linear motion with magnets, thanks for it.

@aol000xw: What you showed us that isn't a loop, only single straight sections. Show me a similar magnet track which is circle shaped, so continously. That doesn't exists, would be free energy from nothing. FROM NOTHING. The potential energy with the ball you put to the system, will be full consumed by friction few seconds later. @Piterx: This would be a working way, but as you can see, power is needed to the system continously. So simple. If you put once the vehicle to the track, and that would run forever, then second law of thermodinamics would be ignored, which is impossible. So if you want to save a few hours of doing the system which won't work (won't work as you imagined, it could be work for a few seconds), you shouldn't do it all. Energy/power for propulsion won't appear from nothing. For a circle shaped track you need continous power for propulsion (because of friction, drag (air)), a simple potential energy input in the start isn't enough. It's so simple, believe this: Magnets create force, not energy. Very important. Because the basic idea of this topic needs energy for keep moving, there is no more a lot of sence to discuss about the original idea. JM1974: I have about 12 neodinium magnets (bar shaped). They are so strong that it would be the biggest challange to fix them. For long travel suspension for off road cars they are pretty badly usable. Good idea, but the construction would be much more bigger than shocks.

Tech-nick wrote the essence: "In theory your truck would be lifted (less weight on the tracks) a bit, but there is no force to put it in motion. Magnets with same poles facing each other of course pushes them apart but the next magnet on the track is pushing against the trucks magnet in equal force --> tracks magnets cancel each other (no propulsion, only lift)." And: You have friction. A moving vehicle in the track generates "friction power" (not only force, power!), which became mostly heat. You don't have any power source for putting power in the system, so you want to generate the power for "fight against friction power" from nothing. This would be a perpetum mobile, as someone said before me. You can make a magnet tarck, which levitates the vehicle, but you have to put power in the track or in the vehicle for propulsion.

I posted this piece last year: http://www.brickshel...ry.cgi?f=505115 I recommend it, very useful. It's a true 4x3 T piece. You think, but it's not true. First of all: this T piece isn't in the RC remote control unit, it's in the steering unit: http://www.brickshel...y.cgi?i=5494285 --> that steering unit is much more useless, than this piece. Anybody, who say it's "illegal", don't know technic theme well. Why is it illegal? Because you have to take apart (with screws --> no damage!) an RC steering unit? You can take it back to the steering unit anytime, screws again, and it's like it was before. I used it many times, for example: http://www.brickshel...y.cgi?i=5634869 ( http://www.brickshel...y.cgi?i=5634833 ) http://www.brickshel...y.cgi?i=5375032 ( http://www.brickshel...y.cgi?i=5374973 ) IMHO in a contest, it also would be legal. Lego produced, damage isn't needed to grab this piece. So simple, it's all about creativity to find parts like this. (the use also depends on the contest rules, if only cataloged parts are allowed, then it's "illegal" to use of course)