Tamas Juhasz

Worm gear: pros: - the same reduction requires less space - large reduction is possible (for example a 16 tooth gear driven with worm gear gives you a x16 reduction) - no backward drive: the wheels can't be steered by the terrain if you use less reduction(for example 1:3 with normal gears) cons: - lot of friction(so unefficient) in the case of high torque in the steering mechanism (steering usually needs the high torque in a TT) - minimum x8 reduction: the smallest gear has 8 teeth, so this is the minimum reduction, which can be too much if you don't want a gearing up after the worm gear (but if you use it, the steering will be very unefficient) - requires more power from the steering motor --> slower steering But these are also depending on the use of the truck.

Thanks all. Instructions: ok, I will upload in the next few days when I have time.

Hello! My newest mini moc is also a Tatra. My goal was to make a 8x8 813 model with realistic Tatra suspension: This was my first moc, which could be build with 1:1 scale from a paper: I always wanted to build a really small Tatra with the wheels from 8842. This wheel has a diameter of 43 mm, so the proportional width is about 11 stud. That's even not enough, too narrow, but I had success with the suspension and drivetrain in 13 stud width. The first and second axle has steering, and all axle is driven and suspended. With U-joint there is no way to build it narrower. I used 3 different shock absorbers. The first axle has harder ones to hold the weight reliable in the front. The steering mechanism only steers directly the left wheels, the right ones are steered by the 9L links: http://www.brickshel...y.cgi?i=5748589 The ground clearance enables 25 mm high obstacles under the truck. Of course it can go through much bigger ones, as can be seen below in the video. The drivetrain is pretty simple Tatra like, with assimmetric left and right side: http://www.brickshel...y.cgi?i=5748587 In the picture it also can be seen that the front 4 wheels are driven with a small 2L thin liftarm to prevent clacking(if it uses pins and pulley). There wasn't problem with that, in every terrain kept the front wheels the correct position. They look like the valve cover of the wheels.( I forgot to take them also in the rear wheels) Maybe from the pictures we can think that the 12 bevel gears can go out in the middle of the axles. They can't. The 2L red axles prevent that (I used strong 12 gears and loose U-joints). The suspension worked well in terrain, this Tatra doesn't carries tons of weight, stronger axles aren't necessary. The wheel travel is about 2 stud or a bit more depending of the axle. Technic inside: http://www.brickshel...y.cgi?i=5748652 The steering M motor is in the front, the driving M motor is in the rear part. The M motor is powerful with 6:1 final ratio. It can be, because the weight is only 761 g. The stability surprised me. In the video can be seen some test. The aesthetics was also important for me, this one isn't a trial truck, more civil version. I had to cut the mudguards to give space for the wheels, and of course it's a bit higher than the real Tatra to have wheel travel. The front grill has a Tatra logo and some covering sticker: The on/off button is in the top of thew vehicle: If you hit the PF connector, the front LED lights will work(video). I didn't want a PF switch, and wanted to try this out. And the video with infos: If somebody needs, I can upload the building instructions.

Thanks for this link. That's a very smart truck, there is no opportunity to build it smaller, although it's totally different compared to mine in functions and realism. It can be smaller without the second receiver and lights, but I didn't want that short trailer.

I uploaded my smallest truck few days ago: Folder: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=520763 My purpose was a very small trailer truck with remote control. The PF RC system rquired the trailer, in the tractor truck there is only space for one micromotor and the suspension. Total length is 42 stud, width is 5 stud in the truck, 6 in the trailer. The trailer's height is 10 stud at maximum. One old 71427 motor drives the rear wheel of the truck with universal joint: Then, 6 of the 12 tooth bevel gears make connection with the rear axle: The steering is done with micromotor. There is 4 functions in this moc: 1 driving 2 steering 3 Led lights in the back 4 suspension There is one receiver for the leds, so they(orange and red) can be controlled individually: Except the truck's driven axle, all axle has suspension. Front: http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5733797 Trailer - the red suspension parts are from the city theme, I like these small live axles, they are perfect for here: The most tricky part was the tractor truck of course. Fortunately I have two large red doors from an old set, so I could do the truck with this looking: I know that the wheels are a bit small for this body, but who cares. If we take a look at this( http://www.autospies.com/images/users/cawimmer430/5678_1.jpg ), then it's not so big. The trailer is full with PF parts. From the front part there are: 71427 motor - AAA battery box - two PF receivers - leds. The few metallic silver grill plates cover the receiver's infra parts, so you can't see them, but the communication between them and the remote controller is still good: For the control the 8879 remote control is recommended, as can be seen in this video: Hope you like it.

Yesterday I found an another solution to control the gearbox: The picture tells everything, I think with this the control is easier and a bit faster, but needs two of the remote controller. What do you think?

Yes, my problem is that it's called a LEGO heli with those lot of custom parts.

"flugfähiger RC LEGO Heli" - it sounds interesting, because all of the RC parts and motors, etc. aren't Lego. It is equal with a regular RC helicopter which carries weight. Why makes it sense to do this with a Lego body? I see nowadays even more models which have a lot of custom parts(like this), and with these the essence(building creative mocs with Lego technic parts) of Lego technic is loosing. A few(1-2) custom parts or custom wheels(like many of us used them in crawlers) aren't makes a moc non-Lego, that's absolute ok.

This is one of the best looking supercar I have seen yet. I really like the front part.

Sounds interesting, but something is hard to solve: if we can make a flying plane with buggy or another motor and sealed wings, how can we control that? The PF receiver's range isn't enough in outdoor. Or do you think about a non controlled(just flying until reaches ground or something) plane? So, if we think about a controlled vehicle, imho helicpoters are better(I know, nearly impossible to make with Lego without wires - but a wired one is half success).

Thanks guys. Yes, it's more complicated than the real Uniknick. This complication is needed for the much better weight distribution. This kind of vehicles can easily fall over. I hold that in my hands at our Malug TT meeting last year. That's a really well made Uniknick with realistic design, as always by Zoli. But there was a couple of roll over during the race. Then later, in september, the central steered TTs with the Uniknick's simple suspension also loved to roll over. That's why I wanted to try out this suspension. The battery box is quite low, turns half with the cab of the axle's turn. That helps a lot, but even this design isn't as stable as a regular 4x4 TT with linked suspension and PP wheels. But has an advantage: allows to integrate the efficient drive train with simple design, even the 3:1 gear ratio (36t - 12t gears) was enough to climb the obstacles in the video.

No problem, but you don't understand what I wrote: "I know, it's not an RC controlled helicopter" ; "I just wanted to prove that Lego can fly from it's own power." That could do it, this is fact. And the most important that it's not a single propeller, which take off. It has a body(ok, small ) and two propellers. I never seen(of course, that doesn't mean that there isn't) an other moc without cables, wich is more than a single propeller, AND can rise up and fly. That's only a propeller. Many of us had succesful experiments with a single propeller. My first experiment was also with a single small prop and the 8L axle about 6 years ago with one pull-back motor.

Hi! First of all, congratulation to Zblj for these soultions. I'm just wonder that nobody remembered at this flying Lego machine: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=500935 I made it last year, and this was the really first flying Lego object. It rised from it's own power. Weights 7g. Propeller max rpm was about 10000. It was already proved month ago: I know, it's not an RC controlled helicopter, but the first flying Lego machine. I just wanted to prove that Lego can fly from it's own power.

Merry Christmas!

I present my newest trial truck, a pretty special one, this Mercedes Uniknick: (folder: http://www.brickshel...ry.cgi?f=515930 ) ORIGINAL: http://www.brickshel...spiration02.jpg This construction has central steering, this allows to have only one gear from the driving motors to the wheels. Reduction is 5:1, or 3:1 (has enough torque with it). I didn't want to make an average central steered vehicle like dump trucks, so I decided to add something new. One of the problems was the stability. This kind of off road vehicles like to fall over, that's enough when one section(front or rear) is turned 90 degrees. So this one has a linked like suspension, but with gears and turntables instead of links( not my idea, TT made it in this truck: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=444654 ): So this construction allows to do these at the same time: There is two version from this truck, one with PP wheels(secondary version) and the one with cutom RC4WD crawler tyres(primary model). The PP wheeled truck weights 1767 g, the crawler wheeled 1423 g. I know, it looks much better and realistic with the RC4WD tyres, that's the main reason I used them. The tyres give a bit better climbing abilities (PP wheels are still good), the highest obstacle was 1,5 times bigger than the wheels's diameter. For steering there is one XL motor to have enough power to do it. It's necessary because of the 16 t turntable driving gears, there are two of them, one on each side to make the steering reliable. There weren't any problem with it. Front lights: The hardest part in the building process was to make the central part, to be reliable and functional with keeping the proportions of the original Uniknick. I made a video for each version. Note the PP wheels abilities compared to the crawler tyre. RC4WD Crawler wheel: PP wheel: Hope you like it.

Thanks all. I think it doesn't need a lot of imagination to implement it in a moc. Anyway it's already built in to a truck I'm working on now, and performs well even under 2 kilogramm of weight(load) in the rear axle. Yes, of course, two of the sliding axle gearbox would be very long. Two of the clutch gear gearbox wouldn't allow to make the current gear ratios(5,3,1.666,1), so this combination is the best compromiss I found. The efficiency is very important for me, in this gearbox there is only two gears in every speed, this is the minimum in a four speed gearbox, which is able to control with simple PF RC. There would be possible to make it shorter without the sliding axle part, and using only clutch gears in shifting, but that wouldn't be so strong and efficient(at least one more gear would be necessary) as now. Feel free to try it out.

Hi! Last week I had an idea of a remote controlled gearbox, which is enough compact for vehicles and has definite control: The special part is the controller, this allows the shifting from 1 to 4 with one hand. You can shift very easily by using this positions: Neutral/start: Then 1-2-3-4 gear: This gearbox sustains high torque too, there weren't any scratches when I tested with XL motor. I was thinking about a gearbox like this since long ago, to have something with four speed to build in my mocs. You don't have to know which gear is momently engaged(like in case of steppers), just select the gear you want. It can shift from any gear to any other one, doesn't matter which is the current gear. The pictures show everything about the construction and working method. Two gearbox are combined: Of cousre, the controller motors can be placed in many other way, this is just a quick solution for working. The ratios are: first gear: 5:1 reduction second gear: 3:1 reduction third gear: 1,666: 1 reduction fourth gear: 1:1 (no reduction) --> so it's the same as the popular four speed gearbox. Folder: http://www.brickshel...ry.cgi?f=518300 This video shows the working, and the shifting times(about 4 sec from 1 to 4) can be also seen:

Thanks for answer, that's the situation. I wanted the working outrigger, but didn't see possibility to make them functionable. With the small pneumatic cylinder it would be bigger and that would require also a compressor.

Thanks. The wires caused a lot of problem in the end of building, but after some modification they could be put mostly in the drivers cab and near to the turntable. In the middle there is a little "empty" space. Actually I made the whole instruction for this moc, there can be seen the outriggers mechanism. I can upload when I have time.

Mobile cranes and small mocs are two from my favourite themes, so I decided to build a moc which fits to both. In the case of mobile cranes a small moc is only small compared to 81,6 or 94,8 (or even PP) wheeled cranes. I chose the Liebherr LTM 1130 five axle crane to build a full RC one: http://www.brickshel...ry.cgi?f=514492 Scale is 1:31, the main aims were: keep proportionate, and to be full RC with the 9 functions. I had to economize with the space, to put in this crane 6 M motors, one 9V motor, 3 conversion wire, one AAA battery box, 4 receivers and more. I haven't thought that the hardest part will be the turntable driving in the building process. Finally, a belt drive was built in with 90° rotated axles, there were space only for that because of the other construction elements. But as can be seen below in the video it works fine. The outriggers mechanism was also tricky. One M motor operates the four legs, in extension process the red rubber band extends the outrigger, then the M motor pulls them back with the string and winds up the rubber band: http://www.brickshel...LTM1130/040.jpg The legs are only for working, they don't support anything. This isn't problem, because the crane can't fall over, it's own weight stabilize it in the case of 50-100 g weight in the hook. With one motor for two functions(outriggers in out - legs up/down) can be save one receiver output, I used that for the front led lights: http://www.brickshel...y.cgi?i=5634921 The nine functions: Driving, steering, outriggers in/out, legs up/down, boom lifting, boom extension, superstructure rotation(fortunately can be in 360°), hook lifting, front lights. There is a very limited space inside, so many functions are driven with rubber bands. I used 43 mm wheels. Main dimensions: length: 487 mm width: 114 mm (95 in the body) height: 128 mm (top of the boom) max. height: 654 mm weight: 1636 g (with batteries) speed: 0,2 km/h number of pieces: 1500 Max boom length: http://www.brickshel...y.cgi?i=5634874 Max. height: http://www.brickshel...y.cgi?i=5634875 The crane needs a flat surface to move, the ground clearance is ~ 1 mm to save space inside. Has a differential in the driven axle: Four of the five axles can be steered: http://www.brickshel...y.cgi?i=5634857 http://www.brickshel...y.cgi?i=5634858 The battery is placed in the front, and two receivers are sitting in the cab instead of the driver : http://www.brickshel...y.cgi?i=5634943 I wanted a dashboard too: The superstructure contains 3 motors, the actuators, covering, and the crane operator cabin. This cabin was the hardest part in the superstructure: Here can be seen in action:

Thanks, I see. Everything ok. (I thought you just have forgotten it, no problem. I used to write the builders name in the file I save, when I saw something interesting) The gearbox itself is yours, but it's also a modified 8880 gearbox, and as you wrote based on Erik Leppens design( http://www.brickshelf.com/cgi-bin/gallery.cgi?f=279654 ; http://www.brickshelf.com/cgi-bin/gallery.cgi?i=2513289 ). This 4 speed gearbox is a very general one, if you want to build in this size, you don't have many possibilities. The challenge isn't in the building of the gearbox, but in the control. To control without NXT or RCX. When I built that, I didn't want a stepper, I wanted a definite control - one controller lever and direction --> one gear. You have right with the autovalve, I modified the description. The situation is that I made it exactly for my excavator, a compact, dual autovalve was needed. The novelty was the formation.

Great moc, you made the axles very compact. But it's a crawler, not a TT. Truck trial(TT) means trucks in hard terrain, at least Unimog or similar. No, they shouldn't be damaged if you do that.

Sariel: It was a big surprise to me when I saw my gearbox in this moc, but the biggest was that you didn't wrote it's not your idea. Please do it. If you use somebody's idea, then write in every description, video, what's the situation. Like I did in a few of my mocs. The gearbox has also a post(11th in this topic): http://www.eurobricks.com/forum/index.php?showtopic=70284&st=0&p=1298278&fromsearch=1entry1298278 Folder: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=504221

If you need a fast vehicle, you need power. It doesn't matter if the motor has high rpm with low torque or low rpm with high torque, only the power(torque*angular velocity) matters. If you have a motor with 60 rpm and 1 Nm torque, the power is ((60*2*3,1415)/60)*1 = 6,28 W. I think from this piston engine with air operating you couldn't get much power, maximum some percent of a Buggy or XL motor. If you need power to speed, then an RC buggy motor (or PF XL, but the buggy is better) is recommended for you. But if you can run this engine at several thousand rpm, it's possible to have the same power(or even more) as the buggy motor. The torque is little because of the short stroke, you can mostly increase the power with increasing the rpm. But in that case the motor will consume a lot of air, so it would require a compressor or a very big air tank. I think it will be useful in low rpm with very little air consumption, so you could operate a car with piston LPE, but without wires and pneumatic tubes from compressor. I'm planning to try out the engine with sealing, now I'm looking for a good string.

I don't have any idea yet. Modding or drilling pieces is not so acceptable for me, imho it would be great only with Lego. I think my motor with your sealing could work well(with sealing it could work only with an air tank - I needed the compressor because of the lot of air loss). I think it's not so plausible that a pneumatic piston motor could operate also the valves. One 9V motor for valves isn't so much in a moc which is equipped with this piston motor. You need remote controlled steering and "throttle" if you want to build the engine in a moc. I don't have better idea.