Madoca 1977

[MOC] Tatra 813 Trial Truck

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Hello everyone,

My new creation is a big Tatra. It is my first 8x8. All problems of size, weight, friction and powertrain were the most challenging for me.

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Total weight: 2790g

2 hard coupled XL motors for 8 wheel drive without differentials. They are connected to each output of V2 receiver #2, powered by 8878 battery of left side. (Motors of the rest are connected to V2 #1, powered by 8878 of right side)

1st and 2nd axle are steered in different angles by 2 L motors.

M motor for 2 speed heavy duty gearbox. 9:1 (high) 25:1 (low)

Working steering wheel and V12 engine.

Openable hood and doors.

External roll cage and LED lights are easily removable.

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This is my suspension setup. The central axle is free from the friction by the force of suspension movement. Each 6.5L springs limit the angle of swinging half-axles. In these limited angles, bevel gears smoothly engage.

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Since the building process was complicated, I haven't made instructions yet. Hopefully it will be available in a few weeks.

I drove it in high gear in most part of the video. Despite heavy weight, not a single gear was damaged. In low gear, it is surprisingly powerful.

Video:

Building instructions and more pictures: https://plus.google.com/u/0/photos/117021167471864977943/albums

I hope you will like it! :wink:

Edited by Madoca 1977

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Good work Madocca! But I DO have to say real tatras dont use portal hubs. What are the total gear ratios and how did you do the steering?

EDIT AWESOME TECHNIQUE used so there is no friction on the main drive axle.

Edited by Zblj

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sick model dude!

i usually don't like tatras, actually i kinda hate them xD but this one looks so cool that i like it heheh

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Good work Madocca! But I DO have to say real tatras dont use portal hubs. What are the total gear ratios and how did you do the steering?

EDIT AWESOME TECHNIQUE used so there is no friction on the main drive axle.

Because I didn't have any proper planetary hub reduction ideas. And I thought using portal hubs was simple and robust solution with minimum friction.

Total gear ratios are 9:1 and 25:1.

High: 12/36 - 8/24

Low: 12/20 -12/20 - 12/36 - 8/24

Since each half-axles contains 36t bevel gear in it, they became bulky and stable. Never bend or twist. :classic:

Steering is simple gear rack and 9L links. 1st axle is steered by 12t bevel, 2nd by 8t gear. Yes, it's not like real.

Edited by Madoca 1977

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Love the details. Cage is Awesome :thumbup:

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Congratulations, it is perfect!!! Its performance is amazing, I didn't now that unimog tires have so much grip, wish I had some :-) Really cool that you are preparing BI for such a big model. I will definetly check them out!!!

Edited by MajklSpajkl

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Another totally awesome model Madoca, though I didn't expect anything less from you :classic: Great job! Looking forward to the parts list and instructions. Thanks for taking the time to make these.

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I like it. We need a Trial Truck hall of fame so new builders can find inspiration.

Edited by PROlego

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WOW, just WOW. Impressive, I couldn't believe it was still climbing up after the 4th axle got on the smooth wood surface. I wanna build something like that when I grow up :laugh:

Edited by miguev

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Remarkable, looking forward to buying instructions! Would love to add to my Technic collection.

Please notify me when instructions are available :laugh: :laugh: :laugh:

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Too bad you did not drive it outside, but it is too shiny to get dirty :)

As others said, one of the best TT. Look, techniques, performance.

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Too bad you did not drive it outside, but it is too shiny to get dirty :)

As others said, one of the best TT. Look, techniques, performance.

I wanted to drive it outside, but It was a rainy day.

Someday I will make the video of my trial trucks crawling outside. :classic:

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I wanted to drive it outside, but It was a rainy day.

Someday I will make the video of my trial trucks crawling outside. :classic:

Stop building for a while. Go outside and enjoy your trucks, man;)

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Great beast!

but as ZBLJ says indeed tatras do not have portal axles, only the pinzgauer does along with a tatra like chassis.

so this model is an improvement on the tratra 813!

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