The much anticipated (at least by me) set Bucket Wheel Excavator 42055. When this monster was announced, I knew I had to get him. Especially the new gear-part 24121 looks like a great addition to the Technic collection. I’m expecting a new wave of MOC from it. Let’s see if this set can meet up with the/my expectations.

To get an idea of scale of the build I’m accompanied by Tiny Toby and Tall Toby.


The box

The box is the biggest I’ve ever had (42009 and 42030 being the largest yet for me). It measures 57.8 x 47.8 x 16.8 cm and weighs 5970 gram. On the front the main model.

Behind the front are pictures of all the functions of the build.
At the back is the B-model, a mobile aggregate processing plant that separates large bricks/stones from smaller ones.
In the box we find another box, containing the bags numbered 1-3, bags numbered 4-8, an XL-motor, battery box and the instructions/stickers sealed in plastic.

In total there are 31 numbered bags.

The instructions consists of 1 large book, 1.9 cm thick and 541 pages long. The book is sturdy, and after the build it still holds together fine. This is the first time I see instructions numbered all the way through. Usually the steps-counter resets after a series of numbered bags is done, but this one counts all the way through ‘till 669. Also new for me was the white squares to indicated where a part needed to added when the pictures came crowded.



New parts

The inventory of 3927 parts can be found here.
First up is of course the 24121, the new quarter gear. It’s surprisingly sturdy and thick. There are 14 in this set, enough for 3.5 full circles

The other new part is the new Bucket 24120. I’m not sure why there is a new version of this, the old one could have been used too. A theory I found on Facebook is that the inserts inside the bucket makes the rocks fall out easier

Part 15458 is new in Dark Blue.

Another thing I noticed: All the 5- and 9-long axles are yellow. I assume that because they needed a few in yellow to do the railing, and they decided to make them all yellow. Makes the packaging easier.



The build – Step 1

Step 1 builds a little dump truck.It's about 95% the same as 42035 Mining Truck.

One bag in step contains only Light Bluish Grey and Dark Bluish Grey Cones and domes, representing rocks. It’s a nice touch, but somehow I feel like it’s an easy way to boost the part-count.



The build – Step 2

Step 2 builds the bottom part of the frame, on top of which the rest can rotate. I found this part a bit boring. Everything is double symmetrical, so often you have to build the same thing twice or four times.



The build – Step 3

Step 3 builds the 2 tracks on the side of the frame. It’s twice the same build.



The build – Step 4

Step 4 builds the structure that carries the 2 arms. During the build I wondered why there were Technic Wedge Belt Wheel (4185) sitting in different angles at the bottom. There were no belts in the inventory, so I was unclear of their use.

Turns out they roll on top of the large gearwheel to make the rotation more smooth.

In this part the first cluster of gears forms.

And the result after completing step 4. It’s starting to get big.



The build - Step 5

Step 5 makes the small conveyer belt leading to the dump truck



The build – Step 6

This is the biggest step in the build. I even had to presort the parts to be able to find everything. In this step the first half of the big arm is created, with the bucket wheel and conveyer belt.

the bucket wheel is put in quite tight. It takes a lot of pulling and pushing to get it in. Once in it’s held in place by 12 gears.

Something strange is happening in this part. To fully secure the connectors to the axle, the axle has to stick out a little, barely missing the other gear.

When completed you’re left with an impressively large piece. This is really a massive build.



The build -Step 7

Step 7 completes the large arm, adding the motor and a gearshift box to distribute all functions.

Not sure why these parts are used here instead of a standard connector. Or why one axle is red.

The driveline for driving, turning and the small conveyer belt are also connected with these parts. Here it’s more obvious. The parts don’t hold tight to the axle but can slide. This allowing some wiggleroom when lowering and raising the big arm.



The build – Step 8

Step 8 completes the model with the cabin, railing and other small stuff. The cabin is a little too small for a minifigure.



The end result




There are 4 main functions:

1. Powering the conveyer belt
2. Powering the tracks
3. Rotating the top. When rotating the top, the small conveyer belt turns with it. You can lock the conveyer belt so it stays in the same place, so the dump truck doesn’t have to move

4. Raising and lowering the bucket wheel. Unfortunately this is done by hand! In a set of 3927 parts I would have thought they could make this motorized?!




- Great parts pack. Almost all parts are standard parts that are great for rebrickable
- Relatively cheap (yes, I’m dutch). In this set the parts are about € 0.06 cent per part. In for example the Porsche this is € 0.12.
- Great new part: The big gear wheels. It’s going to make a lot of great MOCs
- The build itself is mostly entertaining. My build time was about 10 hours.

- Manually lowering the bucket wheel is cheap!
- Step 2 and 3 were kind of boring.


My conclusion is: Get this set! It’s a great model with lots of play features. And if you don’t like the model, you will get a lot of good rebrickable parts.

Thank you for reading. Any comments or questions are welcome in the comment section

Disclaimer: This LEGO set was provided for review by The LEGO Group. Anything said in this post is the opinion of the author and not The LEGO Group.


  • 2 years, 8 months ago Cooperpear987 Level 2
    Great article.  I read this article. it is very useful. Thanksfor sharing this .

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  • 3 years, 1 month ago Gutworks Level 10
    I just bought this set and can't wait to start building it. Thanks for the great review!
  • 3 years, 4 months ago Gaurnim Level 2
    In step 7, you describe the parts that "don’t hold tight to the axle but can slide" (32494). I've been using this to disconnect the 32494 / 92906 couple. This disconnects the motor from the gears when I lend the excavator to the kids. So they can play with it freely without straining the motor. It also allows them to move the set faster, as the motor is really slow, even if it's an XL one.

    I've been having a great time building this set and the kids were awed by it at several steps and when it was finished.
  • 3 years, 6 months ago Fritz38 Level 4
    The B-model sorter goes behind the outlet of the digger, the truck are used for hauling money to the Lego company :D
  • 3 years, 8 months ago bazza Level 9
    Instructions including B Model (Mobile aggregate processing plant) now available @ lego.com
  • 3 years, 8 months ago stagecoachfan Level 2
    The sticker with the technical data on gives the dimensions of the "real" thing as the same as the model but in m rather than cm, indicating an approximate scale of 1:100 making a lego microfigure about the right size to be the driver :)
  • 3 years, 8 months ago dagupa Level 16 MOC Designer DESIGNER
    I thought the dump truck was the same as the 42035, but looking at your pictures I realized it's actually better (At least I like it better). It has the traditional air filters: the white round plates that look like lights.
  • 3 years, 8 months ago ralfralftorres250 Level 8 MOC Designer
    For engineering addicts and enthusiasts... This is something cool. But does the quarter gears have any indents so they can be fixed into a single gear with 4 axles? Also do they have that part in other colors aside from yellow?
    • 3 years, 8 months ago thea Level 29 Inventory Admin ADMIN
      TobyMac is on vacation. Could someone else who has the set help out with questions this week?
    • 3 years, 6 months ago delithug Level 5 MOC Designer
      I know this is a month old now, but yes, they can be connected to form a ring with an overall diameter of 21. They do not exist in other colors though.
  • 3 years, 8 months ago Hogwartus Level 11 MOC Designer
    When will it be avilable?
    • 3 years, 8 months ago Kamteey Level 14 MOC Designer
      IIRC, on August 1st or on August.
  • 3 years, 8 months ago SALB Level 9
    I so want this set! But I don't have the money to buy it. :( I like that new gear wheel though.
  • 3 years, 8 months ago Batupintar Level 13
    I know it's a lot of extra work for reviewing, but for such a massive and expensive model I'd love to see reviews including the B-model as well. Particularly in this case, cause a bricks sorting machine seems spot-on to me as B-model for such a large set!
  • 3 years, 8 months ago solomall Level 10
    When this monster was announced, I knew I had to get him.
  • 3 years, 8 months ago TomOOO Level 2
    You wondered why the flex joints (Universal joints) were used in the build - probably because of the flex of such a large structure would cause the fixed axles to be strained and increase friction
    Thank you for the review
  • 3 years, 8 months ago A.Brickovsky Level 4
    Pictures are quite poor and somehow spoiled your otherwise OK review.
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