K'NEX Mobile Crane Truck V.4




About: I don't always make instructables, but when I do, I prefer to use pictures. Stay instructed, my friends.

Changes made since version 3 :

+ lattice boom structure like on crawler cranes
+ string (yes, string)
+ Ackermann-like steering (almost; still needs a little human intervention to achieve)
+ stronger superstructure

So I found time and a new camera.  Here is the instructable.  There's also some photos of a 300g balance.  Yay!  I didn't bother doing a maximum testt - I wanted to see if it could carry anything at all.  Maybe you can test its maximum capacity? ;)

Inspirations to this model:

Supercar - steering and chassis
Picture of a crawler crane
Picture of a crawler crane
Crawler crane - booms
Lego Technic 8460/8431/8438 and 8421 - outriggers

Total number of pieces: 2046

Just like version 3, I made this "backward"; that is, I photographed it while I was taking it apart.  Also, pay attention to the comments in the photos.  Since there is no caption-option available (or I haven't found it), I have tagged almost every image.  If there is anything that still looks confusing, feel free to leave a comment.  As you can see, it's very lengthy, so make sure you have a lot of time.

It's kind of hybridized between a mobile truck crane and a crawler crane, since it uses the body of the truck but the crane of a crawler.  Perhaps in the next version I'll try to make it more truck-like with whatever K'NEX hydraulic technique I can come up with.


Step 1: Pieces Needed

Photos 1 and 2: You will need at least all of those pieces.
Photo 3: Piece count.
Photo 4: Rods
- 394 Green rods
- 236 White rods
- 254 Blue rods
- 60 Yellow rods
- 6 Red rods
- 1 Grey rod & 3 Black rods
Photo 5: Connectors, small gears, spacers:
- 23 Tan
- 4 ???
- 231 Grey (1 port)
- 20 Light Grey (2 ports, 45 deg)
- 55 Orange (2 ports, 180 deg)
- 62 Red (3 ports, 45, 90 deg)
- 30 Green (4 ports, 45, 90, 135 deg)
- 118 Purple Adapter (4 ports, 45, 90, 135)
- 171 Yellow (5 ports, 45, 90, 135, 180)
- 101 Blue Adapter (7 ports)
- 64 White (8 ports)
- 11 small gears (one must have notch)
- 151 Blue spacers (51 can be substituted by 17 Grey spacers)
Photo 6: Bigger gears:
- 1 Big yellow bevel gear
- 8 small pulleys
- 1 Medium bevel gear
Photo 7: Wheels
- 12 Large pulleys + Large tires
- 1 small tire
- at least 442 cm (14'6") of string

Step 2: Begin With the Chassis! the Bottom.

Step 3: Chassis: Axles

Step 4: Chassis: Steering Column

This is the hard part.

Step 5: Chassis: After the Steering Column...

...we stabilize it (as best as possible)

Step 6: Outriggers: Part 1

We're going to make 4 of these, or two sets of these; I'll show you the first part here.  These are for the front outriggers.  The way they work come from Lego Technic 8460/8431/8438.

Step 7: Steering (and Other Miscellaneous Stuff)

Here we put on the steering stick.  You can substitute the yellow rod for a longer one and attach a wheel if you like; I just never bothered with it since I was more concerned about creating a working crane.  Also, the steering stick doesn't do quite an adequate job at turning the wheels (another thing to keep in mind for my next design...), even with the connectors holding it in place.

Step 8: The (base of The) Superstructure

Follow those pictures and captions!

Step 9: The (base of The) Superstructure: Part 2

Step 10: The Front.

...as in the part covering the front wheels.

Step 11: The Cab

...is where the driver sits.

Step 12: Outriggers: Part 2.

We made these before.  The outriggers themselves are exactly the same as the front ones, but their connection points to the truck are slightly different.

Step 13: The Superstructure:

And now we get to the crane part of the program.

Step 14: Strings!

In this step, we will construct the string drums, as well as the crane cabin floor.

Step 15: The Crane Gets a Cabin! (sort Of)

Step 16: The Hook.

Here is the double-hook for the crane.

Step 17: The Counterweight.

Step 18: The Boom.

Step 19: The Final Stretch!

Don't forget to read the notes!

Step 20: Complete!



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18 Discussions

Lightning Boy

5 months ago

What happened to V1? 'Cos I found V2 and V3 but not V1???


Question 11 months ago on Step 14

Do you have pictures of the strings and how the work?


6 years ago on Step 4

your method of attaching the rods so that they are fixed to each other is quite similar to how i did so with my K'nex orrery, very interesting...

1 reply

Reply 4 years ago on Introduction

Sorry for the super late reply, but life got in the way and I haven't any new ideas pop up. I checked out your orrery (where I live, they call it a mobile; yours is probably a mechanical mobile) and I wish I had more of those orange peg pieces! It is similar; however, I don't have the central blue connector support. If you look at a tower crane, they use similar triangles. I suspect it is so that it doesn't bend easily; using purple interlocking connectors will make the connectors unlock under its own weight.


7 years ago on Introduction

really nice, K'NEX should make this an official set
eeehm, well they better don't, because it will have lots of stupid bricks and mini-knex.....

2 replies

Reply 7 years ago on Introduction

completely right,you cant even get a set from a non-online store any more, all they've done is made it more fiddly than it should be!!!!!!!!!!!!!!!!!!!!!!


Reply 4 years ago on Introduction

They should bring back "Classic" sets where bricks were nonexistent, and make new sets from "classic" pieces.


6 years ago on Introduction

Not sure I have enough pieces, but this is too cool for not to at least try and make it!
Wish me luck!


Reply 6 years ago on Introduction

Ah. Thanks. Wasn't sure what the official name for it was. I can see why people call them y-clips. Knex.com says "Standard Black Rod/Connector". Might just go with black rod "Y" connector (or 人)


i like it but it took me 5 hours really fun ........................................................................................................................................... no steering but i put my own if you want to learn how to make steering better go to building tips on knex.com watch and copy the video if not i will post on youtube.com http://www.youtube.com/legodude4292001 it will be posted today if not next weekend on june 30th please subscribe:)


7 years ago on Introduction

Made it - took a few hours, but tis done. Tis rather awesome, but the steering isn't as good as in the version 3.

3 replies

Reply 7 years ago on Introduction

Been thinking - how easy do you reckon it will be to change the steering in this, for that in the Version 3? Only problem i can see (at a glance) will be the front outrigger :/ - will have to look into it tomorrow


Reply 7 years ago on Introduction

Thanks for building it!

Yes, the steering sucks in this one; putting the front outrigger there probably wasn't the best idea. The reason for the steering sucking is that I was going for something a real truck might have.


Reply 7 years ago on Introduction

Ah right. I'm going to build the chassis and steering from version 3 and then try to change it so it takes the outriggers and the rest of the body from this one :)