42043 Alternate - Mobile Crane




Alternate model for 42043 Mercedes Arocs Truck.

My first try on making one set MOC. I decided to build a mobile crane, because Arocs has great amount of universal parts, and it was quite challenging to fit four functions into the supestructure with given range of parts (for example - it uses almost all gears provided with the set). It has three manual functions - steering (three axles are steerable), supestructure rotation and fake V6 engine behind the cab. Four motorized functions are powered by L motor trough two gearboxes. First one allows to fold/retract stabilizers and fold/retract crane arm. Second one operates winch and pneumatic pump. The winch can be locked in place.
It was quite challenging to make it all works with limited amount of parts (gears especially), but it ended quite well.

The model comes with full building instructions, that are divided into submodels (like chassis, cab, deck parts, supestructure, crane arm, etc.)

Please not that 42043 set DOES NOT comes with a string, so this model needs additional, at least 2m long string.

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Name 42043 Alternate - Mobile Crane
Designer M_longer
Designed 2016
Inventory 1836 parts
Theme Technic
Alternate Build of 42043-1 Mercedes Benz Arocs 3245


  • 5 months ago szymanski1991 Level 10
    I will leave here few words about maybe the best I was ever building. The Mobile Crane made as C Model of Mercedes Arocs set by M_Longer.
    Why? I must divide answer for few topics.
    Form. It’s god damn C Model. I’ve seen some C Models in internet, they all great but = at least form those which I assembled till now – this is probably the best. Mercedes Arocs have many functions and A LOT of parts to even make completely other creation from it but… This one is Amazing. It’s fully functional, nice looking Crane model with extendable boom. The number of functions closed in superstructure, level of fulfilling small room for it. I mentioned about many parts in Arocs but for sure there is never enough of gears for making mocs.
    • 5 months ago szymanski1991 Level 10
      Drivetrain and steering. Let’s start from the beginning, the truck. There are 4 axles. One of them is “driving” axle connected by differential to V6 engine on front. And this is first difficulty – Arocs engine unit is Straight 6-cylinder, construction of V – shape must relay on connectors. Second big difficulty. There are 3 steering axles and they are working flawlessly. The turning radius is surprisingly tight, operated by The Hand of God steering knob is situated on rear. Ok, I was mentioned the difficulties, but what hard in making steering mechanism? Do anybody see gear racks in Arocs? Exactly. There are no gear racks so steering axles are connected only by gears, beams and connectors. I can’t even imagine the level of complexity to design system like this. Wow.
      Superstructure. Whole Power Functions and pneumatic have to be on super structure so it’s super complex to pack everything on small area. Power functions. There are four of them, powered by PF L Motor and connected by gearbox dividing power.
      First function is transmitted through the turntable element on fundament of superstructure to the truck, for operating the outriggers. Outriggers are big asset of this model, much better than original Lego outriggers. When they are extended, whole model is not only supported by them to stop moving but even hanging on them. Stable. Reliable.
      Second Function: operable winch. Here of course we must add String, as Arocs have no string in inventory. I used original 200 cm long string from Crane Truck. The winch is well designed and do not move itself. Constructed on worm gear of course. Minuses? Two of them. Firstly: the winch movement is very slow because of ratio of gears BUT as we know it’s C Model and there are no gears left for it. Second because of gear transmission Sometimes Gear leading to winch I rotated a bit by red 16 tooth gear leading to pneumatic pump. It’s because the “clutch” part of red gear is near to bevel gear. Again. Because of complexity of superstructure is probably unavoidable.
    • 5 months ago szymanski1991 Level 10
      Third function: Extending the boom. Of course, boom is extendable, it’s another place where gear rack is needed to operate. MOC creator used the gear racks from Arocs outriggers to create it. Again, only minus is slow working and again – unavoidable with limited resources of gears. But there is another BRILLIANT idea. Boom have its own type of clutch, preventing for engine/gear damage after boom is fully extended. It’s made from Two long pins with stop bush and one round connector. Parts are connected by connector and by bush side to axles. When axle from drivetrain side rotating there is enough friction to rotate structure but if boom can’t expand more it’s stop rotating. I like this idea much.
      Last, fourth motorised function is powering up the pneumatic pump. The air is provided to rise two pneumatic pistons elevating the boom. Curious fact: the pneumatic system used here only rising the boom, after moving the lever in pneumatic selector, gravity doing the job with lowering it. And again. Speed. It’s super slow. Exactly like in Arocs but to be honest – this one small pump can’t be fast. Two or three of them could make the job but not one.
      Last function of whole construction is rotating the superstructure which is manual, with knob situated on truck, next to HOG steering. Nothing to add here.
    • 5 months ago szymanski1991 Level 10
      In conclusion the construction is brilliant, number of functions and usage of parts is great. There are some problems but as we know, this is C model. Steering can’t be better without gear racks and faster working of Power Functions could be achieved only with greater number of gears. This is not a Mobile Crane set but C Model for another set. It’s damn nice.
      Instructions. Must say that quality of instructions was not only great but even “Lego Level”. That was the best made instructions for MOC I ever seen, with axles length and clear steps without mistakes (ok, one with length of one tube but easy to notice and fix).
      Details. There is a driver’s cab with small seats. Set do not contain small steering wheel, so creator mounted Mercedes emblem to pretend to be steering wheel (which look kinda nice ) and “Dashboard gauges”. On superstructure there is third seat for crane operator. There are other things like usage of Digging Bucket Parts to cover the battery box sides, looking very smooth and fit the superstructure. Whole construction with boom raised and expanded, standing on outriggers doing the hella good impression.
      This is very good MOC. Worth every $ spend on instructions. Worth it. Thanks for good time building it.
      Now… Now I want to build bigger crane. Must buy the Rough Terrain Crane or Mobile Crane. I just see that I need to collect few hundreds of parts more to create build LTM MOC :D
  • 5 months, 1 week ago EVANMAC Level 6
    hi, just completed the build and tested all the functions, works a treat. This is my first MOC build and I found it had good level of complexity requiring time and attention to complete. Loved it.   thanks   Evan
  • 5 months, 2 weeks ago szymanski1991 Level 10
    Hi. On start: love this modell.
    I'm on the stage of gearbox when adding first pneumatic hose. Page 110 tells that hose should be 216mm but actualy we should use longest gray hose, the 37L / 29.6 cm
    • 5 months, 2 weeks ago M_longer Level 14 Designed this MOC DESIGNER
      The instructions still shows 216mm? I was sure that I have reuploaded version with proper length. I'll give it a look tomorrow. Thanks for noticing!
  • 6 months, 3 weeks ago wu1 Level 1
    Very nice design. I will try
  • 11 months ago M_Trance Level 4
    Nice MOC, had fun building it! Very well done.
  • 1 year ago Shandyman Level 18
    WoW! Another terrific alternate here. Well done sir!
  • 1 year, 6 months ago Nick3 Level 12
    This is a great model big well done to m longer
    The build is a lot funner than the Arocs, love the steering and the gearbox most of all as it is really complex and fun to make (took me about 4 hours to make just the gearbox :D), big congratulations on that i was really impressed.
    I would recommend this to anyone!
  • 1 year, 8 months ago jkr_007 Level 6
    I hawold like to ask you how can I generate list of parts which are missing in original set 42043 set?

  • 2 years, 1 month ago jonny789 Level 3
    Great model, I just built it yesterday! The instructions were flawless and top quality as well - I especially liked that you used quite many pieces per steps, that's how it should be for advanced models. I have found though one tiny mistake in the instructions: the grey pneumatic tube that should go from the pump to the selector at the other end of the turntable is definitely short (216mm is just not enough), it would need something like 35 cm. I managed to do it with two tubes though. 
    Other controversies: perhaps the cabin doors could have been made operable and the steering wheel is offset.
    But other than these minor issues this is an outstanding model and a very entertaining build!
    • 1 year, 4 months ago magnus2509 Level 4
      Thanks for your comment, first I thought I did sth. completely wrong...worked with 30cm for me.
      right now I' halfway through and really looking forward to the finished model.
      Looks great so far :-)
  • 2 years, 1 month ago Wietze Level 4
    Why no answer on mine question is there no other  way to get this buiding instruction mail me please [email protected]
  • 2 years, 1 month ago Wietze Level 4
    why can i not buy the instructions via ideal.
  • 2 years, 2 months ago didoDM17 Level 2
    I would like to know how it is possible to buy instructions of this moc .I have tried with credit card but I received nothing
  • 2 years, 2 months ago travor.19 Level 2
    I can buy instruction only through PayPal?
    • 2 years, 2 months ago M_longer Level 14 Designed this MOC DESIGNER
      • 2 years, 2 months ago travor.19 Level 2
        Я бы купил эту инструкцию если оплата была не через PayPal
  • 2 years, 3 months ago Hawker17 Level 3
    I spotted this MOC a year ago. Unfortunately there were no PDF instructions available then, only through software. I was very happy to see there are PDF instructions right now, for a very friendly price. Your instructions look very clear to me and i can't wait to build it. I will post a little review later. Thanks for your work.
  • 3 years, 2 months ago psmyth Level 16
    almost finished this MOC and I must say that the instructions are great. A lot of work was put into these plans and well worth the money!! thanks
  • 3 years, 2 months ago JackieWu Level 5
    You did a nice job under the constraint of limited pieces. Very impressive.
  • 3 years, 2 months ago Lego360 Level 12 PRO
    Very nice looking c-model of the 42043. Planning to build thuis one. Great job.
  • 3 years, 2 months ago psmyth Level 16
    this is a great MOC...nice building instructions!!
  • 3 years, 2 months ago BrickbyBrickTechnic Level 19 MOC Designer
    I've already done this! It's my most popular MOC! But you did amazing!
  • 3 years, 2 months ago Technic Scale Crawlers Level 15 MOC Designer
    Cool design but don't really think it's worth money just looks like LXF file instructions plus some of your pictures and you explained give some proof. Not trying to be rood but it really looks like it. I love this design but don't think it's worth it.
    • 3 years, 2 months ago M_longer Level 14 Designed this MOC DESIGNER
      Well, it all depends on what are you looking for. Building it in way you have described would be quite challenging though :)
      • 3 years, 2 months ago Fasztival Level 6
        Alter-lego fantastic job, do not pay attention to the cry babies.
        You are not the first person in the history of the world.
        Hell, along that thinking, LEGO should give us free LEGO, LOL wtf eh?
        • 3 years, 2 months ago Technic Scale Crawlers Level 15 MOC Designer
          So your point is mam oh sir. Excuse me but how ignorant you are, I said free instructions on lego digital designer and was talking about why I think it shouldn't be for sale but ppl never agree. Thats just how we role in the human race.
    • 3 years, 2 months ago alter-lego Level 14 MOC Designer
      Given the amount of work required to generate building instructions for a model of that size, I tend to think that asking 10$ for it is not scandalous at all. Then this is up to you to decide whether you are interested in building the model or not. If you like the model though, 10$ is certainly worth it!
      • 3 years, 2 months ago Technic Scale Crawlers Level 15 MOC Designer
        My reasons why I don't think it's worth it (since I wasn't descriptive enough)

        1.Just think about it free digital designer that can gererate FREE instructions. Then probably little editing, I mean what else could you do.
        2.Also yes it takes a lot of time and effort but every single moc on this site you have to at least do a little effort.I try to do lxf and photo sequence. I use lxf for making part list and I do photo sequence for instructions but you could do lxf to.
        3.I wouldn't care if this was like 3-5$ for instructions makes sense sound like a little donation. 10$ Is just him trying to make money
        4. Somebody came up with this idea before and it's for free just get that one like really.

        Is that not enough?
        • 3 years, 2 months ago alter-lego Level 14 MOC Designer
          Well, generating the instructions from a lxf is indeed not the most time consuming, but creating a lxf for a model of this size and adding steps and submodels is several hours of work (and if not, I pay for the trick!). The fact that someone had a similar idea before does not mean anything. This implementation is very different from the other "published" one, and cannot be considered a copy. Again, compared to other notices advertised on rebrickable, there is nothing special with the price I think.
          • 3 years, 2 months ago Technic Scale Crawlers Level 15 MOC Designer
            Still don't see point of buying them, and I never will.
            • 3 years, 2 months ago M_longer Level 14 Designed this MOC DESIGNER
              OK, few things:
              You can make instructions even inside the LLD. But their quality is... unacceptable :)
              It took about 90-100 hours to make those instructions. That amount of time was needed for making submodels, building a whole model digitaly, editing the instructions itself (puting raw submodels often ends in unreadeable steps in the instructions). Then a good thing is to build a test model, which allows to check if there's something wrong with submodels, their placing or just with step order.

              I am aware that there are much more pricey instructions available, but I decided to make my one cheaper, so more people would have chance to use it.

              If you do not wish to pay for them, I am OK with that.
              • 11 months, 1 week ago rrr_bbb Level 3
                Hi. So apparently, the instructions are now 13 Euros? So that's about 20$, no more 10$... Is the price correct?
                The set is pretty neat, very nice  work! But 20$ seems pretty expensive to me!  I wanted to build the set with my 5 year's old boy who loves Legos and saw the set on YouTube and I was ready to pay the 10$ for your good work... I just hope there's an error in the 13 Euros price...
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