[MOC] Tatra T813 8x8 PROFA

[Madoca 1977]

Hello everyone.

This is my second Tatra model.Comparing to previous Tatra 813 Trial Truck built in 2014, it is bigger, heavier and a little bit faster.

Weight: 3810g  Length: 62.4cm  Width: 24cm  Height: 25cm

-Powered by 2 SBricks

-6 L motors for propulsion

-2 M motors for steering

-M motor for 2 speed gearbox

-Working steering wheel and V12 engine

-Openable doors, front grill and roof hatch

The model was specifically inspired by a unique truck of Jansa Team participating at real truck trial events. I tried to replicate overall look as possible without using any stickers. The cabin became one stud longer than it should be. Also using many system parts was somewhat compromising as a Technic builder.

This time I omitted offset axles because symmetrical structure was more robust and efficient. Each side of half axles are independently driven via two parallel drive shafts. That enables slightly smoother turning than previous one adopted single drive shaft.

Body parts are removable by pulling out both seats and two 5.5L axles behind the rear bed.

When I completed the chassis early in 2018, it never came to my mind that LEGO would officially release "game changing" planetary wheel hub. Admittedly those bulky half axles using portal hub look outdated in 2019.

The core of chassis contains bunch of L motors which I called 'Six Pack Abs'. The gearbox is simple yet packed 16 gears into tiny space between L motors.

Although suspension mechanism is not like real Tatra, pairs of swing half axles move like real one. That realizes good off-road capability.

The steering angle of 1st axle is twice as 2nd axle. Two hard-coupled M motors move 13L gear rack via dual pinion gears. For more powerful steering, I did not use white clutch gears. Consequently geared down motors keep rotating and make clicking noise when gear rack reaches end position.

After all, this MOC ended up to be just a big truck driven by old technology. (Strangely it sounds like aged Tatra 813 in modern truck trial events...) Still I am happy with the result and sharing another massive 8x8 model. If you like it, feel free to put colorful stickers on it, make alternate cabin design or build more accurate chassis with new hub parts.

Building instructions available on Rebrickable.

Edited August 6, 2019 by Madoca 1977

[1gor]

Great Moc.

Looking forward to see version with new wheels hub from 42099 set...

[Mechbuilds]

You are amazing @Madoca 1977! Thank you so much for making instructions! 

[xpst]

Genius Design, Thank you for sharing the instruction!

[LegoTT]

Hello, in your previous 8x8, it was not possible to put two 16t gears in the portal hub, because it led to many gear clicking. How about this one ?

[ArsMan064]

I really like how you made suspension!

[jrx]

Wow, really good looking MOC with impressive power. Can you tell which inclination it masters?

Edited August 6, 2019 by jrx
Blindness ... ?‍♂️

[Bubbha]

Another great MOC from Madoca, congratulations, your skills are amazing... 

[Madoca 1977]

6 hours ago, LegoTT said:

Hello, in your previous 8x8, it was not possible to put two 16t gears in the portal hub, because it led to many gear clicking. How about this one ?

I’m sure that will lead to even more clicking because it is much heavier and putting larger tires.

[nerdsforprez]

Don't comment much on MOCs but I absolutely love this one.  The performance is out of this world for such a large build.  I know L motors are fairly powerful, but really, it seems you are drawing every ounce of power out of this build you possibly can.  Also love the looks, the color combination is terrific.  Usually I vie for third party tires in and off-road build, but the CLAAS tires look and perform great. 

 

*Sigh* been more or less away from the hobby for more  a year now..... can't wait to get back.  This will be one of the first builds I try once I am back.....

Edited August 5, 2019 by nerdsforprez

[brunojj1]

@Madoca 1977 Great to see you back again with such a fantastic build ! I´m always blown away by your building techniques. Your "simple" gearbox, efficient motorization and the uncompromised looks of the entire vehicle . And thanks for sharing free building instructions - you are a noble Samurai  .

Edited August 6, 2019 by brunojj1

[Mister Phes]

Very nice, @Madoca 1977 - your MOC has been posted on the Eurobricks frontpage!

[T Lego]

Great to see another brilliant MOC of yours.  I realy love your suspension setup. Thanks for sharing!

[Zerobricks]

Brillinat idea with suspension, so the axles can swing in pairs. Now we just need an upgrade to the new hubs which will allow for much smoother steering and even more torque.

[MajklSpajkl]

Awesome build! Still can't believe that it is possible to build so dense. Fantastic!

[Madoca 1977]

6 hours ago, brunojj1 said:

And thanks for sharing free building instructions - you are a noble Samurai  .

Thank you! For me sharing MOC is purely enjoyable. Making money is not. Even though I’m not rich at all. The truth is, I’m a stubborn cynic who wants to go against the grain. 

[Madoca 1977]

1 hour ago, Zerobricks said:

Brillinat idea with suspension, so the axles can swing in pairs. Now we just need an upgrade to the new hubs which will allow for much smoother steering and even more torque.

This odd suspension linkage was necessary to make chassis narrower because steered axles with portal hub move wheels deeper toward the center of frame.

For years I’ve been searching how to conquer terrain and gravity. And I’m still looking up your 8 XL powered FOX 8x8x8. This is yet another answer to it.

[Madoca 1977]

19 hours ago, jrx said:

Can you tell how heavy it is and which inclination it masters?

3810g is more than 1kg heavier than the old one. The inclination in the last part of video is 40 degrees.

Surprisingly there was no gear clicking in that scene. I think because all wheel (8 pairs of bevel gears) equally shared the load.

[Mestari]

This is just great! I love to see you back online, I was getting worried you took longer break from LEGO ;)

Your Tatra looks serious, like it means business ;)

[LEGO Train 12 Volts]

Ouch what a beast!

Amazing video and impressive performance!

[rm8]

Amazing model. Must build!

[jrx]

6 hours ago, Madoca 1977 said:

The inclination in the last part of video is 40 degrees

That's formidable! My Zetros prototype managed 45 degrees but unfortunately I missed to put it on the scale. The final truck was limited to 25 degrees at a weight of 4,55 kg.

[AFOLegofan66]

So glad to see you back with some beautiful LEGO models and instructions...thanks. I always enjoy building them. 

[KD123]

Thank you for such a wonderful creation!  Glad to see you are back! ?

[Madoca 1977]

I am very sorry, I rechecked instructions again and noticed that I have used wrong photos for step 24-25. I just fixed it. If you have already copied early version of instructions, please check the (tiny) differences and use correct photos.

Turns our concentration on working became lower than in my 30s...