Liebherr LTM 1250-5.1 with crab steering

[Dawid_Szmandra]

Hi, I'd like to present my latest project, the Liebherr LTM 1250-5.1. Some people will probably be bored because it is almost the same crane again, but maybe it will interest someone.

LEGO Liebherr LTM 1250-5.1 by Dawid Szmandra, on Flickr

The project began with a new steering control concept that uses two servos to steer a long beam along the vehicle. The turn of each axle is connected to it and by moving it in parallel, all the wheels turn by the same angle, moving the beam to the left on front and to the right at the rear, the wheels will turn respectively.

This allows the individual axles to turn by different angles with normal steering and the same angle with crab steering.
it is also very easy to use, because we only have two servos and by changing the polarity of one of them (with the button on the SBrick profile) we change the steering mode between crab/normal.

By controlling one servo, you can also turn only the front axles, or only the rear axles (in real cranes there are also such steering modes). I don't know if I have described it clearly, but I hope so. ? The effect is best seen in the video.

Steering + drive is made as a separate module for easier build and can be seen here:

LTM 1250-5.1 by Dawid Szmandra, on Flickr

The rest of the model is rather standard. 7 motors, 4597 parts, 3 section boom with a third section moved by a string. I tried to make the model as simple to build as possible, therefore it is very modular, with a limited number of illegal techniques and weak connections. It should be simpler and nicer to build than the previous LTM 1070.

LEGO Liebherr LTM 1250-5.1 by Dawid Szmandra, on Flickr

Some sample pages from the manual:
 

Flickr: https://flic.kr/s/aHsmSgNcHk
Instructions: https://szmandracranes.e-junkie.com/
Instruction om rebrickable: https://rebrickable.com/mocs/MOC-57421/Dawid_Szmandra/liebherr-ltm-1250-51

 

[1gor]

Dawid, if some people are bored, let them keep this to themselves; I personally find this crane very impressive 

[MinusAndy]

Surely nuanced cool features like this are exactly what people are interested in. Awesome build!

[Jeroen Ottens]

You have a very high standard!

I have been thinking about a similar setup for the steeringmodes, but I thought the long beam would not be stiff enough to give proper steeringangles for all axles...

Did you do something special to reinforce it?

For the rest it is a masterpiece

[Dawid_Szmandra]

Here is the beam. Nothing special to reinforce it, but it is quite strong for bending

.

Edited November 26, 2020 by Dawid_Szmandra

[neonic]

2 hours ago, Dawid_Szmandra said:

Some people will probably be bored because it is almost the same crane again, but maybe it will interest someone.

Yes, it's maybe same/another crane, but bored?? Never 
It looks great. Smooth and lot of details. 
Specially the steering is impressive. One moment just turning, the next 'crabbing'. (just wondering how you do that, motor?)

 

[steph77]

How do you want us to be bored facing such creation????

I have some question sir :

- Does the direction setup be based (basically) on two independant servos. Each of them connected to respectively 2 and 3 axles with different lock angle?

I guess it cannot be as simple due to fact that crab steering need the same angle for each axle when normal steering mode needs différents angle for each. How do you solved that?

- The linear actuator is a XL one? true? However, the maximum raising angle doesn't seems to be that important. Wheight issue?

 

GREAT model. You surely do not have to hesitate in case of recidive :) 

Edited November 26, 2020 by steph77

[Dawid_Szmandra]

7 minutes ago, steph77 said:

Each of them connected to respectively 2 and 3 axles with different lock angle?

No, front servo is connected to front end of the beam, rear servo is connected to rear end of the beam. Axles are connected to the beam. The beam moves sideways (parallel or X-shaped)

12 minutes ago, steph77 said:

The linear actuator is a XL one? true? However, the maximum raising angle doesn't seems to be that important. Wheight issue?

Yes, it is long actuator, but it is still much too short, so the boom raising angle is too low.

[Andman]

Nice, i really like it!

[pdw]

Very nice, and a very elegant solution to the steering.  I assume the beam is only pinned in one place, and that all the other connections slide in the central channel of the beam?

I'm working on a model with mixable crab/normal steering, but I only have two axles to worry about!

[JintaiZ]

Personally, I'm not into cranes, but this is amazing!

[Erik Leppen]

Now this is something! At it happens, exactly the same crane in the same scale is on my to-build list, and I started twice, but never finished. But I wouldn't come close to your level of realism in looks I think. Your model looks exactly like the real crane. It's as realistic as it gets in terms of looks, and packs quite a punch under the hood in functions. Edit: also I like that it's not oversized for what it does. /edit

I'm quite surprised by how well all those functions seem to work, and that there's some lifting power as well (which is impressive at this scale). Especially that steering seems really quick and smooth. I know the "beam method", but I didn't expect it to work on this scale.

I honestly don't get why TLC doesn't grab these kinds of licences and brings out these kinds of sets. I mean, this is what the Lego medium is about, right?

Dang, I should really get my crane up and running :P

Edited November 26, 2020 by Erik Leppen

[Brickend]

Looks amazing and moves really well for the size, I guess limiting the driven axles keeps the drivetrain losses to a minimum?

Was it difficult getting permission from Liebherr to reproduce their logo for sale?

[Jubuilder]

Absolutely fantastic model! Love seeing your cranes, they never get old :) 

[Dawid_Szmandra]

On 11/26/2020 at 5:07 PM, pdw said:

I assume the beam is only pinned in one place, and that all the other connections slide in the central channel of the beam?

Exactly this

On 11/26/2020 at 5:53 PM, Erik Leppen said:

Now this is something!

Thanks, after my dark age (~2007) I spent a lot of hours studying your brickshelf gallery, you were one of my authorities back then, so it's nice to hear that! 

On 11/26/2020 at 6:27 PM, Brickend said:

I guess limiting the driven axles keeps the drivetrain losses to a minimum?

Yes, the drivetrain is simple and effective, And 1 driven axle seems to be ok for flat surfaces.

On 11/26/2020 at 6:27 PM, Brickend said:

Was it difficult getting permission from Liebherr to reproduce their logo for sale?

Hmm, I haven't even asked them yet. So stickers are currently illegal, but I'll ask them. 

[suffocation]

The looks and functionality are mind-blowing

Still struggling to wrap my head around the multiple steering system - I'll have to try it out.

[mnpumar]

Wow! Thank you so much for making the stickers and instructions available for purchase, I just ordered them! Do you plan on releasing larger models like the 7 or 9 axle in the future?

[Dawid_Szmandra]

On 11/29/2020 at 7:43 AM, mnpumar said:

Wow! Thank you so much for making the stickers and instructions available for purchase, I just ordered them! Do you plan on releasing larger models like the 7 or 9 axle in the future?

Sure, but not in the near future.

[mnpumar]

23 hours ago, Dawid_Szmandra said:

Sure, but not in the near future.

Looking forward to it  thanks!