42128 Single-cabin mobile crane (my first alternate model)

[MP LEGO Technic creations]

Hello everybody!

I'd like to present you my very first alternate model, built from parts provided by the 42128 set.

I started building this one because I wanted a new challenge, something different from builds I usually do.

The model uses about 85% pieces (some spare parts included).

It took me about 3 days to build and I'm quite happy with the result (since I haven't done something similar before, I don't know whether I should...)

Maximum height of the model is 71 cm.

 

Anyway, here are the features:

 

3-axle steering with proper geometry

Working fake engine connected to 3rd axle

Front and rear outriggers

Manually rotated superstructure

Cabin lifting

Cabin tilting

Cabin's boom extension

Folding right rear view mirror together with main boom's transport support

Winch with a ratchet mechanism

Pneumatically elevated boom

Pneumatically extended two-stage boom

External boom's extension

 

Any feedback is appreciated.

 

 

 

 

And a video:

 

Edited July 19, 2022 by MP LEGO Technic creations
video added

[1gor]

Actually it is very cool alternative; interesting is that there is a cab only on superstructure like on 42082 set. Undercarriage reminds me a bit on legendary 8421 set

[GerritvdG]

Well done! 

[MP LEGO Technic creations]

17 minutes ago, 1gor said:

Actually it is very cool alternative

 

12 minutes ago, GerritvdG said:

Well done! 

Thank you!

17 minutes ago, 1gor said:

interesting is that there is a cab only on superstructure

I took the idea from this (it doesn't seem to be a common feature, though). Anyway, I decided to go this way because there just weren't enough parts to make a good looking (to me) standard mobile crane with 2 cabins...

 

Edited July 19, 2022 by MP LEGO Technic creations

[GerritvdG]

I like the outrigger mechanism, which solution is used? Can’t see it clear…

it reminds me of the mechanism of the trailer outriggers of the Arocs B-model.

[Jundis]

Very nice an original B-Model!

Sadly the 42128 doesn't contain another gear rack to make the two stage boom extend even further :-/

Side note: Sariel is currently building this exact vehicle in the scale of 42082.

[Jurss]

Good. Could have been official B-model

[Erik Leppen]

This is great. Love it. There are two things I particularly liked.

1. those outriggers! I love how they move down and out at the same time, and stand at an angle. There must be some clever geometry inside that makes this work.
2. pneumatic extension! I didn't expect this one. The range is naturally limited, but the principle is there, and it's something very rarely (if ever) seen in Lego. And the third inner boom is of course an added bonus! I wouldn't know of a simple way to icnraese the range, beyond using string, but I believe you already used up all the set's strings for the winch and inner extension.

But actually, I like many things. it looks like the steering radius is pretty small, which is good. Also, I believe the set has only one steering axle, so you must have used nonstandard ways to make the other axles steer. Also, the whole cabin lifting is also neat. I know some real cranes do it, but I don't believe I have seen many Lego cranes doing it.

Also, considering this comes from one set, I think your color scheme is also still rather sane. There's no mishmash of colors, it looks quite organized with the orange boom and the blue cabin operation. The gray front and rear ends of the undercarriage look a bit messy, but it's functional enough, and you had to work with limited parts so it's understandable.

There's only one thing I liked less, that is, that a single cylinder for the whole boom seems a bit too little. But I understand it's by the parts limitation, and seeing from the video, it seems to work better than I would have expected, I just would have prefered a double cylinder personally. However, you used the other cylinder for the extension, which is much cooler so yeah :)

If you don't mind, I saved the source pictures of the white Liebherr crane to my "Lego inspiration" folder, as it looks like a fun subject to build in the future, when I'm in a crane mood again :)

[MP LEGO Technic creations]

2 hours ago, Erik Leppen said:

There must be some clever geometry inside that makes this work.

 

18 hours ago, GerritvdG said:

which solution is used? Can’t see it clear…

In fact, there is no marvel going on here... 

The red thin liftarms are powered and the blue one belongs to the frame.

Hope this schematic is understandable.

 

2 hours ago, Erik Leppen said:

pneumatic extension! I didn't expect this one

That's indeed my favourite function

 

2 hours ago, Erik Leppen said:

I wouldn't know of a simple way to icnraese the range, beyond using string, but I believe you already used up all the set's strings for the winch and inner extension.

Maybe I haven't clarified this above but the extension mechanism uses 2 long thin pneumatic cylinders (one for each section), so one string is still left unused... (the other one had exactly the wanted lenght to reach the ground even from the full height so no tying was needed)

 

2 hours ago, Erik Leppen said:

that a single cylinder for the whole boom seems a bit too little

Yes, you're quite right. It's enough when the boom is retracted, fine when extended, OK when extension mounted but putting more then 100 - 150 grams of weight is starting to be way too much for one cylinder.

Of course, I could've connect the cylinder in a different way but then the angle of fully lifted boom was too little, though the force had increased. 

I'd also prefer two cylinders for this but the set provided only a single one.

2 hours ago, Erik Leppen said:

Also, considering this comes from one set, I think your color scheme is also still rather sane.

Thank you! As the set didn't have only one main colour, making a B-model which wasn't rather speckled was indeed a nightmare 

Edited July 20, 2022 by MP LEGO Technic creations

[Gray Gear]

I have never seen a single-cabin mobile crane before! I never thought about it, but it makes so much sense to make it like this! Very cool you made this work so well in LEGO form.

[AFOLegofan66]

Fantastic alternate design well done!

[GerritvdG]

1 hour ago, MP LEGO Technic creations said:

Hope this schematic is understandable.

It is, thanks! Just a clever linkage, I really like it!

[thekoRngear]

Really liked this soundless approach. A very well thought MOC. Liked the stabilization. Wish the cab could remain horizontal when the cab's boom being raised. 

Edited July 20, 2022 by thekoRngear

[MP LEGO Technic creations]

3 minutes ago, thekoRngear said:

Wish the cab could remain horizontal when the cab's boom being raised.

This also came to my mind but in fact, that doesn't make sense that much because real cranes sometimes need to only tilt their cabin, without lifting it.

Edited July 20, 2022 by MP LEGO Technic creations

[Thirdwigg]

Great job with this alt build. Like others, I love the crane extension. An the outriggers are a perfect solution. It's crazy how such a simple solution can be so effective.

Can I assume 42128 came from your TC22 win? Way to use the set for this build!

[MP LEGO Technic creations]

2 minutes ago, Thirdwigg said:

Can I assume 42128 came from your TC22 win? Way to use the set for this build!

You're absolutely right 

Anyway, I've just found your first alternate model, too.

12 minutes ago, Thirdwigg said:

An the outriggers are a perfect solution. It's crazy how such a simple solution can be so effective

However, this left me with 4 small LAs unused, as those were too weak to use instead 

Edited July 20, 2022 by MP LEGO Technic creations

[gyenesvi]

This is a pretty neat alternate build, I like how much of the functional elements of the set are reused, great unusual functions, and I also like how well the color consistency is kept despite the set having many colors.

17 hours ago, MP LEGO Technic creations said:

However, this left me with 4 small LAs unused, as those were too weak to use instead

So did you try one LA per outrigger and that was too weak?

[m2fel]

Great model. Wish this would make it to the front-page as it really shows what I like in technic builds. Clever functions although it's an alternate model with part limitation! Technic is more than diecast like models :)

[MP LEGO Technic creations]

2 hours ago, gyenesvi said:

So did you try one LA per outrigger and that was too weak?

Indeed. I wanted the outriggers to extend by 90 degrees (like in the A model) but that didn't bring much stability (like in the A model) because the outriggers started to retract under the model's weight once the chassis was tilted a little.

So I abandoned this idea and started thinking about a different mechanism where the LAs wouldn't be loaded with the model's weight when extended. This ended up with something completely different where no linear actuator was used at all and worm gears instead.

1 hour ago, m2fel said:

Clever functions although it's an alternate model with part limitation!

I'm glad you like it!

[Johnny1360]

Great what you have done here, my favorite is that is something I am totally unaware even existed, bonus points for that one, lol. Also that it is an alternate of an current set is great as most of my mocs are done like this, I have the most fun, limiting available parts for a moc.

Thanks