[MOC] MLC300 Crawler Crane - free instructions available

[mdemerchant]

Hi everyone, I have a simple model to share based loosely on the Manitowic MLC300 crawler crane.  The model is fully manual and is about 1m tall in the most basic configuration you see below.

I started building this is January because we had visited my family over Christmas and my nephew who is really big into Lego wanted me to help him build a crane.  It wasn't practical to build much of a crane during the few hours we were at his house and he was mostly playing my kids anyway but later on when I was thinking of things to build I thought I should do a simple crane that would be easy for him to build and fun to play with.  So I started building some crawlers with the intent of just making a generic crane but then I thought variable position counterweight makes it easier to play with and it might as well look like something so I decided to loosely model it on the MLC300.  Liebherr cranes seem to get many more models, both Lego and diecast, so this is an under-represented subject.  I did keep the design really simple, fully manual with cranks and knobs prominently sticking out and no trim like walkways, ladders and railings.  I think you could put them on using system parts and really improve the looks but they would be super flimsy.  Designed for an 8 year old, it's basic.

The real crane, shown below, is I guess what you might call a small large crane.  It's 300-400 ton capacity depending on the configuration so it's at the low end of heavy lift but it's much higher capacity than the 100 ton type crane that you might commonly see around on job sites.  It also looks physically small for it's weight class, at least to me, I guess because of the shape of the crawlers and body.  I happened to see a real one working on I95 in Miami in March and when you see it around those 100 ton type cranes it doesn't look so small in reality but I think it is smaller than the equivalent Liebherr for example.

The special feature of the real crane is the VPC system which is a motorized ballast carrier than runs along a gear rack along the underside of the superstructure.  This allows the weight to be moved to different radius to balance the load on the crane.  I think this is part of what allows it to be a bit smaller, they don't need such a beefy slewing bearing because it can stay better balanced.  The system can also be extended with what they call VPC max where they attach a big extension frame in place of the ballast carrier and the whole frame can move in and out with the ballast then moving along the frame as well.  My implementation of VPC is super simple as you can see below, I just have the ballast tray slide on 15L beams on the superstructure.  Putting in a gear rack would have been nice but I just couldn't see any way to do it without needing more clearance between the bottom of the superstructure and the tracks and I didn't want to lift the structure any higher or make the whole thing a bigger scale.  In general the whole crane isn't very "technic" but it does have gearing on all the winches to make them faster and ratcheting locks.

The model has the basic crane features:

• Two crawlers, no tensioners in them
• Slewing superstructure
• Tilting cab, can also be rotated around the front they way it would be for transport
• Winch to adjust the A frame and main boom angle
• Winch for the main hook
• Winch for an auxiliary hook
• Simple gravity ratchet mechanisms on all the winches
• Optional boom tip extension for the auxiliary hook
• Extra winch - used with the jib (there's a jib? we'll get to that)
• Moveable counterweight - I built them hollow and put a few old batteries inside.
• I stuck a pneumatic cylinder on the A frame which is used on the real crane during self assembly to pick thing up without having to bother with another winch.  Not super useful here, it's decorative and not even connected to a pump.
• All modular so you can quickly break it down into the same types of pieces as you would the real crane for transport.  You can also extend or shorten the boom by using more or fewer insert modules.

Of course, once you start building a crane then you think, this is nice but it could be taller.  It could be a more complicated configuration.  It could lift heavier things.  This of course led to building a bunch of accessories to have the VPC Max functionality and the full crane configuration with luffing jib.  This is pushing the envelope for an 8 year old but if he has enough parts to build it it's light enough that it won't seriously injure him when it inevitably falls over.

The accessories I guess add a couple more functions, the VPC moveable counterweight frame and an extra winch in the derrick to adjust the main boom angle.

Overall I'm pretty happy with how this turned out.  It's pretty simple but it's fun to play with and actually I have it sitting on a table with a smallish boom configuration and it looks ok as a display piece.  There is certainly room for improvement depending on what your goal would be.  Could be much more detailed for a display model.  The one area I'm not that satisfied with is way the main winch is built into the boom.  It's flimsier than is ideal and easily redesigned but I haven't gotten to it.

Since the whole point of making this was to have something my nephew could build, I have made instructions for it.  This was my first attempt at making instructions for anything which took much longer than I expected and led to lots of cursing at Stud.io "features".  I have not built it from the instructions to test them but looking through them carefully I believe they are all correct and should be clear enough.  The build is very simple, if there are minor issues I'm sure anyone reading this forum will have no trouble solving them.  If anyone wants to try I will appreciate any feedback on issues you find.

Instructions for the basic crane can be found on Rebrickable here https://rebrickable.com/mocs/MOC-164685/mdemerchant/mlc300-crawler-crane/

The extra bits for the bigger configurations are here https://rebrickable.com/mocs/MOC-165101/mdemerchant/mlc300-vpc-max-jib-expansion/

There are some extra renders and pictures in the Bricksafe folders https://bricksafe.com/pages/mdemerchant/mlc300 and https://bricksafe.com/pages/mdemerchant/mlc300-expansion

I haven't put the .io files into Bricksafe but I can if anyone is interested in having them.

 

[Lego Tom]

Very cool! Thanks for posting.

[allanp]

Nicely done 

[Jurss]

Somehow simple, but really cool! Nothing too much.

[nerdsforprez]

Haven't been on this site for a while but glad I stopped by.  This is a great build and thats awesome you are offering instructions.   These are the Technic builds I like.  Nothing overly complicated, but teach basic mechanical and physical lessons that offer tons of playability.  Great post (not to mention I think we both have a thing for cranes).  

Edited November 26, 2023 by nerdsforprez

[Jundis]

That is so great! I highly admire you did it in a smaller scale, this seem a perfect pick for this very crane. Fantastic model!

[mdemerchant]

13 hours ago, nerdsforprez said:

Haven't been on this site for a while but glad I stopped by.  This is a great build and thats awesome you are offering instructions.   These are the Technic builds I like.  Nothing overly complicated, but teach basic mechanical and physical lessons that offer tons of playability.  Great post (not to mention I think we both have a thing for cranes).  

Well I do build things other than cranes but so far it happens that only cranes have turned out well enough to bother with posting.  But yes I do like cranes, they are interesting machines that seem simple but actually have a lot of functions.

Thanks to everyone for all the kind words.