Tatra phoenix

[GuiliuG]

Hello everybody ! Today I finished my last project which is a tatra phoenix with the 8110 wheels.Unfortunately, the truck does not work properly and I'm a little dissapointed with it but, as we say, it's trough mistakes that we learn, isn't it?

The truck weights 2kg153,it's heavy and only four axles support all the weight. These axles propuls the truck via two differentials placed perpendicularly to the wheels. The friction is huge on these axles and the Xl motor has a hard time, same with 12T/20T-8T/24T reductions.

The steering works well but the turning radious is rediculous, due to the tatra suspension ( difficulties to build a decent steering with such a suspension in lego). There is an ackermann effect. This mechanism is assured by a M motor and 12T/clutch-8T/24T

Two hard springs begin to be insufficient to support the cab weight and the front suspensions work not perfectly ( this phenomenon is increased when the cab is lifted but a priori, we do not drive the cab lifted ^^). Rear suspensions work weel because there is less weight in this part of the truck.

The compressor is also powered by the Xl motor via a gearbox ( so I can choose either the propulsion or the compressor) and the reductions 16T/20T-12T. The frame is not strong enough and move a lot when the pressure begins to be high. It was my first pneumatic creation and now I know how I had to build a frame when there is a compressor in it ^^.

Moreover, the skip can't be lifted with the pneumatic cylinder because too much force is needed ( it weights approximativly 400g) and the compass lift (?) breaks before. Contrariwise the skip can be lifted on the right or left side just with the pneumatic cylinder. It's impossible to put two pneumatic cylinder due to the frame tightness but anyway the compass break before and I can not reinforce due to the tightness of the frame...

As you can see, it's far to be perfect but I have learnt a lot of things and I'm very pleased with the building experience I have had :)

So, after this long comment, here are some pictures ( others are in my brickshel galery) and the video :

Edited August 22, 2011 by GuiliuG

[Rafal]

In my opinion, it's a copy of 8110 Unimog with a bit another bodywork.

But it looks good.

Edited August 22, 2011 by Rafal

[Dutch_EE]

In my opinion, it's a copy of 8110 Unimog with a bit another bodywork.

I don't know what you have seen from the Unimog, but the chassis is completely different. Not only is the chassis a bit bigger, the biggest difference is that

The Unimog has pendular suspension, this has individual suspension. The only thing that is equal to the Unimog, is that there are Portal axle reduction boxes.

These can also be baught without buying the Unimog.

[P4trickvH]

Great looking MOC, only it looks like the air cilinder has a hard job getting the back up.

[GuiliuG]

Maybe is it important to read what I write? ;-) I have clearly said that the cylinder can not lift the skip and it's for this reason that I help it.

Otherwise, my truck has nothing to deal with the frame of the Unimog8110!

[timslegos]

Nice job on the tarta. The cab looks really nice, especially with the new Unimog wheels. Its a shame that the cylinder has a hard time lifting the bed.

tim

[captainmib]

These axles propuls the truck via two differentials placed perpendicularly to the wheels. The friction is huge on these axles and the Xl motor has a hard time, same with 12T/20T-8T/24T reductions.

Well, i think i have a rather logic question on this: why did you not put the differentials between the wheels as normal?

The solution you have causes a lot of friction on those gears and axles - the differentials can make this go away for a huge amount i think...

For the rest - looking good. Just try and go on with making improvements.

[GuiliuG]

Because it's a tatra suspension. If you don't know what it is : look at this picture which comes from the official site :

As you can see, if you put a differential between the wheels, the suspension system can not work because they oscillate thanks to a central axle;-)

Edited August 23, 2011 by GuiliuG

[captainmib]

Because it's a tatra suspension. If you don't know what it is : look at this picture which comes from the official site :

As you can see, if you put a differential between the wheels, the suspension system can not work because they oscillate thanks to a central axle;-)

Ah, thanks for enlighten me, i didnt know about tatra suspension and stuff.

But, is it not possible to use the central axle with gear which connects to a normal placed differential to oscillate?

[Alasdair Ryan]

Have you tried using a rubber band or a bit of string attached to the bed?

[GuiliuG]

@captainmib : Yes, I think that it's possible but it's not the solution used on real tatra :)

Alsadair, I haven't tried use a rubberband and it's still disassembled because I was not satisfied with it !