[MOC] Max's Tatra 8x8 Trial Truck

[MaxSupercars]

I’d like to present you my version of Tatra 8x8.

About 3 months ago I decided to create a crawler but I didn’t want to make simple common 4x4 crawler. I like Tatras so I decided to build my version of Tatra because of superior independent suspension, very good climbing performance of 8x8 in rough terrain. I didn’t want to make very big model like Madoca1970’s great Tatra so I have decided to use the medium sized 81,6 balloon tires. The main purpose was to make strong 8x8 Tatra that can climb on obstacles or do easier wall tests.

Main characteristics

- 8x8 Drivetrain with final 1:3 gear reduction

- 4x PF XL-Motors for drive

- 2x L-Motors for steering

- 2x Li-Po Rechargeable batteries

Dimensions (LxWxH): 51x19x21cm (64x24x26 studs)

Weight: 2,2 kg

Design details:

- fake custom V12 engine

- openable doors

- adjustable seats

- first aid kit, fire extinguisher, spare wheel, side details, exhausts

Video

Driveline

The main objective was to make powerful drivetrain. I begun with 2 XL Motors but as the weight of the model rised I had to add second pair of XL Motors. The problem in this case was to transfer huge power and torque into drivetrain. The advantage of Tatra drivetrain is that there is one central drive shaft without any universal or cv- joints which could be the weak point. That’s the advantage in comparison with live axles or other suspension or driveline types. Because hard coupling of 4 XL Motor cause the gear skidding I decided to transfer power on 2 places of driveline – before and after 3rd axle. This solution makes the 3rd axle very strong what is very usable by climbing on obstacle when only central 2nd and 3rd axles got contact with the ground. I didn’t want to split the driveline to the front and back, because so I can use the power of driveline also when any of axle is in the air and the load will be redirected to axles with the grip.

Steering

I wanted to have fast steering and big steering angle 45°! So I used 2 PF L Motors and I didn’t gear it down much. Steering got quite much power. After many tests of different steering systems I decided to use the gear racks and linkages what gave me best results by bump steer. From the same reason I placed the linkages down also to minimize force to turn the portals hubs with pivot point more inside of model. When I placed steering down I had enough place at the top to place another parts of the model for ex. the steering L-Motors and the body remained despite of this very slim.

Suspension

Tatra suspension got a lot of advantages. As mentioned the driveline remain straight and can transfer a lot of torque and every wheel is suspended independently. As you can see in video the halfaxles are shifted by offset like in real Tatra. Connection of halfaxles with central driveline via Linear Actuator holders makes very rigid connection and there NEVER appear the skidding between 12 tooth bevel gears what is huge advantage. At the end of halfaxles and at the end of driveline are portal hubs with 1:3 reduction. This increases end torque and adds extra ground clearance for Tatra. For ex. the real Tatra 810 uses the portal hubs. Other Tatras use mainly wheel reductions.

Electrics

Each of XL Motors is being fed by separate PF IR Receiver, pair of receivers are fed by separate Li-Po rechargeable battery. I used my own blinking electrics for blinking of upper orange warning lights what gives the model very attractive feature and makes fun by playing.

Design details

By building I started with chassis, suspension and steering. When I was finished and model got very good performance, at that point got model weight for about 1,6 kg. After adding all the details and eye catchers like cabin, body, fake motor, spare wheel, exhausts, first aid kit, fire extinguisher etc. added additional 0,5 kg what forced me to add additional XL Motors without reducing the Tatra speed and gearing it down. The final weight is about 2,2 kg and this fine details can be removed in case of Truck Trial to make the Tatra lighter and give better performance.

The cabin is inspired by Tatra 813 cabin but is shifted more to the back to reduce the long nose and give better climbing performace.

The working fake V12 motor is placed on right place at the nose between seats like in real Tatra 813 and is air cooled by a big fan. The front hood can be opened like in real Tatra.

Steering wheel is working and connected to steering system.

The doors are openable and the seats adjustable. In the cab are nice details like fire extinguisher and first aid kit. Behind the cab are located exhausts and big spare wheel with some other nice details at the side. On top of the cab are blinking orange lights and side mirrors.

The rest of the body is very slim and creates nice line to the end with look on powerful XL Motors and Li-Po Batteries.

Enjoy images and video and I'm open to answer your question when interested...

Max

Edited December 9, 2015 by MaxSupercars

[Technic Jim]

Very nice model with a lot of power. It looks like a good climber as well.

[Zerobricks]

Well done! We dont see many tatras at this medium scale, and you did a really good job. The total gear ratio is 1:3, right? Those wheels are actually a good choice, because unlike the bigger 94,8 ones, these are from softer rubber AFAIK.

Good work with syncronizing the audio and video too.

Only thing I would like to see is this beast's belly and underparts

[MaxSupercars]

Thanx, yes the final gearing is 1:3. I add it to description. :)

I add more images later. In video can the underpart be seen. :)

Max

Edited December 8, 2015 by MaxSupercars

[jorgeopesi]

Powerfull tatra .

[Trango]

Wow. Bookmarking this post. Plenty of inspiration here for a medium 8x8. By all means do share more material!

[Nalyd997]

Well done and awesome presentation! Loving the colour combo and how cool the xls look in the back. I have to get back into the trial truck groove!

Edited December 9, 2015 by Nalyd997

[SmeggedAU]

Really nice, great job!

[Beck]

I love the simplicity! Very clean design!

[nerdsforprez]

Max... i am sure you have posted more but I think this is the first thing of yours that I have seen. Great job! I love how compact it is..... and the fake engine and fan :wub:

[2LegoOrNot2Lego...]

Amazing build! Nice scale indeed and it is so strong! Also love the color combinations and the interior details, especially the first aid kid!!! :thumbup:

Next would be to compliment you for the video: i compliment you for the video... This is really well done... What I do like to see is some more off road action!!!

[Milan]

Hey Max, nice to see your new truck. Very nice colors and mechanics. Hope we will see more such great mocs from you!

[Victor Imaginator]

Max, very nice truck. So much nice little details, while motors stay uncovered, i like this, really add awesomeness to MOC) And colors are very nice. Did you tried lime rims too, at least four at one side?

Edited December 9, 2015 by Victor Imaginator

[9 fingers]

Looks great. The color scheme is a burner. I realy like it.

[SevenStuds]

Epic! The photos are magic! I saw your site and there is definitely a lot of skill behind that 5D!

The Tatra performs very well and I think that medium size builds like this are far better as power to weight is at an advantage.

How much worse do you think the performance would be with only 2 receivers?

[MacKaiwer]

Really nice and well done gearing, powerline and transmission. Looks are superb and V12 fake engine is just eye candy I like it very much

[flyboy01]

looking GOOD!

[MaxSupercars]

Hi guys,

thank you for comments. I answer them later... :)

Here are some climbing tests of my Tatra 8x8. I didn't include it in original video because of poor quality and mess in background. That was my test area. Tatra must complete this task otherwise would not see the real sunlight and would not deserve to look outside... I wanted to post you this video from developing phase to have a look at it's abilities. As you can see it is really strong.

I make later better video as soon I find enought time to make it on higher quality level.

Max

Edited December 9, 2015 by MaxSupercars

[Grandadbrick]

I like that very much indeed.

I built a 6x6 crawler using a 1/10 scale rc hpc wheelie king.

Got all the chassis and running gear axles etc complete but stuck with the body. This has given me the idea to use Lego for the cab and load area.

Thanks,

Steve

[metulskie8]

Fantastic Build :thumbup:

[Edwin Korstanje]

Stunning Tatra Max .

It's looks great and drive almost perfect for a trial truck, only in my mind it's to high geard and to fast(maybe to powerfull )and loose grip in your first video.

The presatation is fantastic

[2LegoOrNot2Lego...]

Indeed a mess in the background... :thumbup: ...but that does not change your Tatra does well!!!

[MaxSupercars]

Powerfull tatra .

Yes... that was the main objective. Thank you. :)

Max... i am sure you have posted more but I think this is the first thing of yours that I have seen. Great job! I love how compact it is..... and the fake engine and fan :wub:

Yes I love the fake engine a lot. First I used the normal big V12 TLG engine but I wanted somwthing different. This one suites very well I thing... Thank you :)

Amazing build! Nice scale indeed and it is so strong! Also love the color combinations and the interior details, especially the first aid kid!!! :thumbup:

Next would be to compliment you for the video: i compliment you for the video... This is really well done... What I do like to see is some more off road action!!!

I build first simple body but then I wanted to do it prettier. By Trial truck every gram of weight is minus so I could go the Model Team way. When I was adding the first aid kit I though on you. I knew that you like it. Thank you Ingmar... :)

Stunning Tatra Max .

It's looks great and drive almost perfect for a trial truck, only in my mind it's to high geard and to fast(maybe to powerfull )and loose grip in your first video.

The presatation is fantastic

Yes you're right. It's a different Trial truck. I do not like the lazyness of normal trial trucks so I wanted fast version with fast steering and high ground clearance. Thank you. :)

Thank you all for the comments :)

Max

Edited December 12, 2015 by MaxSupercars

[TheNextLegoDesinger]

don't you have problems steering because of the ofset of the wheels?

[MaxSupercars]

No problems... look at video at 2:45. You can see that the one linkage connection point on the rack is one stud shifted too. :)

I'm now working on smaller Tatra where I used other solution. The halfaxles are on one line and I used different type of steering suitable for smaller models.

Max

Edited December 12, 2015 by MaxSupercars