Mini RC Tatra 813 - 8x8

[Tamas Juhasz]

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.

Edited February 7, 2013 by Mbmc

[captainmib]

Wow, this is a really cool build. Nice to see an 8x8 with steering in such a small space!

And it looks like it can quite handle those ramps! (but maybe the stairs were a bit to much )

[rm8]

Masterpiece! So compact and functional!

[jorgeopesi]

I saw on you tube, great work again, I have to build one of these.

[Zerobricks]

Really great! Its so small, yet functional!

[DLuders]

If somebody needs, I can upload the building instructions.

Yes, please post the Building Instructions!

[rumpletump]

I love the bottom view pictures. There are some great ideas in your work

[Tamas Juhasz]

Thanks all.

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

[Tamas Juhasz]

The instructions are available here:

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=523224

I only made 120 pictures for it, are they enough?

[jorgeopesi]

For a small Tatra like this sure 120 pics are enough , welldone.

[Feri84]

Great MOC! I love Tatra 8*8.

[DLuders]

I have compiled all 161 JPG images of Mbmc's Lego Technic Mini RC Tatra 813 - 8x8 into a single, 10.3-MB PDF file, available for download via SkyDrive here.

[Doc_Brown]

I have compiled all 161 JPG images of Mbmc's Lego Technic Mini RC Tatra 813 - 8x8 into a single, 10.3-MB PDF file, available for download via SkyDrive here.

Thanks Dluders!

And well done Mbmc for an awesome small Tatra! Its performance is fantastic.

[jerryyao]

Really Cool model, good looking and full function!

[Junpei]

Why does the drive motor have 14t gears connected to it? Or is that the steering motor?

[Tamas Juhasz]

That's the steering motor with the 14t gears. They are a bit stronger than the 12t ones (after my experience). And they can be hold stronger in the axles, in this case you have half stud to hold the bevel gear in place. I like that the 14t gears are flat compared to the 12 ones. Sometimes they are simply better.

[Junpei]

OK thanks Mbmc! I always thought they were weaker. Coincidentally, I was over at a friend's house just hours before typing this and I saw some 14t gears, and he said that I could have them. I guess I can try them out, and I also like how they are flat, and are good for meshing at angles that are not 90 degrees. They are also much more similar to real ones than the 12t gears, right?

[Tamas Juhasz]

I think they are stronger a bit because I have less broken 14t gears than 12t. The old material is more rigid, stronger, but because the rigidity they are more likely to brake.

Yes, they can be use in severeal unique configuration, for example with 24t gears as a normal gear (not bevel). Shape: the 14t ones are looking like old industrial bevel gears, nowadays we use thicker gears, like these (and 12t ones): http://www.google.hu...img.T2tzlW4l5Is (and the teeth are angled and bent in most cases)

Another thing: the 14t gear is the smallest which can drive a 1stud wide chain.

Edited May 19, 2013 by Mbmc