Leif

[WIP] 8x8x8 sub structure of crane, the big style

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Gents, bear with me. this is my first MOC in 30 years :classic:

Cranes then and cranes now, but for the time being just the sub structure. My plan is to add the nowadays more or less standard Ultimate 42009 superstructure

together with afol1969 boom, modified by myself some time ago, making third part of the boom stronger, described here http://www.eurobrick...00#entry1996084

This is an 8x8x8 all wheel driven, all wheel steered. I skipped suspension this time, got my hands full with the build anyway and it would take some time to figure out a sturdy suspended structure.

I stayed with the portal hubs although they have some issues concerning steering geometry.

The machine is driven by 1 XL PF and it seems powerful enough as well as modest speed, good for a crane.

steering is PGA technic - Pretty Good Ackerman :sweet:

and as a matter of fact, the machine passes the carpet test :thumbup:

I had a different gear ratio to 2nd and 3rd axle and that one did not pass the carpet test so I've been there and back.

I also had a weak drive train in first version, grinding where I fed first diff from engine from time to time, but still it passed the carpet test without any grinding so I would like to call it flying colors - so far! adding weight may prove something else..

this is a ver 1.0 and the build is already improved right after pics taken so please share any insights or recommendations but I am might be on some of them :tongue:

Wheel colors are of course temporary, If I finish I may invest in some to get get color matching!

Overview:

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backend

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frontend

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Steering!

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Belly shot

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old and bad version of drive train and engine

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new and improved drive train!

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Not bad for a combeck MOC! I would reinforce the drivetrian though, where the second pair of 12:20 tooth gears drive the differential. Also add some bracing where tthe worm is spinning so it doesnt push the beams apart.

Edited by Zblj

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Not bad for a combeck MOC! I would reinforce the drivetrian though, where the second pair of 12:20 tooth gears drive the differential. Also add some bracing where tthe worm is spinning so it doesnt push the beams apart.

thanks a lot!

Can you point out where to reinfoce drivetrain? first pic of drivetrain is old, first version, and not is use, 2 last pics are current and it feels quite strong?

The truck is still a skeleton so reinforcements will be done, for example around worm gear for steering. funny thing is clutch wheel disengage long before any beam pushing so no dealbreaker...

I had a different gear ratio to 2nd and 3rd axle and that one did not pass the carpet test so I've been there and back.

I would like to clarify that I meant gear ratio to 2nd and 3rd axle steering, rack and pinion - not the drivetrain if anyone thought so :blush:

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Good try. There are quite a few 8x8x8 setup without suspension but in compact design. you can google them easily.

eg.

If this is gonna be BIG style, you may need more torque by adding XL motors in order to keep your carpet test success :blush:

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If this is gonna be BIG style, you may need more torque by adding XL motors in order to keep your carpet test success :blush:

Yeah I know! I have 5 XL motors on the shelf som I am ready to add :tongue:

Naturally I will also sooner or later build a larger superstructure, to match scale!

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Crane in place! At this moment I basically added the Ultimate 42009 superstructure with a few changes. along with afol1969 boom, with some reinforcements by myself.

The big change and a new idea, double turntables..

One turntable inside the substructure where the protruding beam is attached to lower part of turntable, and after that attached inside crane superstructure. Are you still with me..?.. :wink:

This idea really stabilizes the superstructure to the extend of more or less bending the chassi rather than the "classic" near-popout of turntable!

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And some pics of the crane from different angles. the 8x8x8 still passes the carpet test and has a pretty good Ackerman geometry :classic:

If this MOC continues the superstructure should of course be rebuilt to match scale! Right now it is just Proof of Concepts (POC) of different ideas!

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So what's next? I don't know really. I am not really into cosmetics, just a rough edged builder..

I should build outriggers of course, but then I have to extend the chassi some in order to fit them between the wheels and that would require more or less a whole tearing apart and rebuild..

If I build outriggers I can promise they will be powerful and stable!

Drivetrain is still sufficient but adding one more PF XL motor would not hurt. There are some grinding gears when driving on an extra thick carpet so I though of have another motor at the other end of the drivetraing in order to offload some. We'll see, still - first MOC in approx 30 years :sweet:

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I think you could use homemade Lego L.A.s for this scale, you could have more power and balance with the rest of the MOC.

Edited by jorgeopesi

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I think you could use homemade Lego L.A.s for this scale, you could have more power and balance with the rest of the MOC.

So far the Lego L.A. s really have no problems lifting. Homemade LA will of course require a whole new superstructure so that is another story to put together..

Welcome back to moc'ing!

Thank's a lot :sweet:

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Well, you could say I',m bumping an old thread but it is my own so I figure it's ok :classic:

New and improved version of this 8x8x8 chassi.

Steering has been simplified using one single train of axles across the entire structure and racked gears with different distance instead of different gearing. Steering motor is temporarily installed though.

Motors have been better integrated into the chassi. 2x XL hard coupled geared down 8:24 - 12:20 -12:20 (diff) and finally 20:28 (portal hub)

Colors have been sorted out!

The machine is strong as a horse! Steering has been upgraded to RGA - Really Good Ackermann and passes the carpet test, with load, with flying colors! and having the Unimog Tyres along with portal hubs and still have decent Ackermann - I'm proud!

Still - this is probably the end of the line for this machine. I have learned a lot and, being a quite new AFOL, I am still in the learning curve. My next project might be some kind of crawler and I will probably build 1 or 2 of Madoca's excellent MOCs in order to pick up some ideas and insights

I have analyzed and taken notes of my building technique compared to proper MOCs and I know, and have concluded that I still build the old way - bottom and up, instead of the new no studded technique - from inside to out.

That is, I build a chassi and try to cram in the motors :blush: rather than building a drivetraing and get a good chassi surrounding this.

However, I know that my machines are quite sturdy and with good bracing, but I have to rebuild so darn many times due to not being able to foresee needs in the structure! need to change tactics sooner or later!

Oh well, some closing pics of the machine. As said, 8x8x8, Ackermann, Portal hubs. 2 x XL driving. strong as a horse!

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Tell me, is it ackermann because each axle has a different steering lock?

Well a pic says more than a 1000 words

170px-Ackermann_simple_design.svg.png

But apparantly I had a brain fart on axle 1 and 4 since they have not compensated for this on axle 1 and 4. only on axle 2 and 3.

I know why, I took a last minute decision to change the width of the vehicle and for some reason forgot to rebuild steering rack! oh well, not in production yet so no recall needs to be done :blush:

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