This is the only LEGO Technic set released in the second half of 2016 which is not a model of a licensed property, and I also applaud the Danes for experimenting with something different to the countless number of regular excavators and other yellow construction vehicles. 42055 Bucket Wheel Excavator is also the biggest LEGO Technic set ever produced, not only in size but also in piece count. There is a natural limit to how big sets can be, considering the flexible qualities of Technic parts, and with this set this limit seems to be nearly reached...
Box and contents
The total amount of bags inside, excluding the ones containing the hefty 550-page instruction book and Power Functions elements, is 32. Just so you know where your money goes: of the 3,900 parts more than 1,800 pins are included, as well as over 140 gears (including gear racks and turntables) and over 270 axles. The amount of Technic liftarms and beams is just as impressive, numbering over 800. It is a true parts pack, perfect for designing your own LEGO Technic creations.
The first three bags, all numbered "1", are used to construct the white mining truck as well as containing an assortment of grey bricks used as stones.
Bags 2Now it is time for the real deal, starting with the base of the bucket-wheel excavator.
The centre of the base is formed by a turntable (of the new beveled type introduced last year) with an axle going through it that drives the tracks. This is accomplished by a rather straightforward assembly of axles and gears with a double-speed reduction. Like its real-life counterpart, this excavator moves very slowly. Considering the size of the machine, I was a bit surprised to see that only the front axle is actuated. Although smoothly moving the thing on tracks is not much of an issue, it would have made more sense if both axles were linked to the central gear assembly.
The construction of a central ring of gears concludes the base of the build. This ring is comprised of a new piece: a gear rack in the shape of a quarter-circle. It has inner 35 teeth (making the total circle 140 teeth), a diameter of 21 studs and it is cast in Bright Yellow [TLG]/Yellow [BL] (Element ID 6151167 | Design ID 24121). The rack has a half-stud thickness at the end, allowing it to combine with other gear racks of similar type. Besides the axle holes at the ends, it contains eight pin holes and one more axle hole in the middle. These are placed in a way such that pins attached to the structure below can hold it into place: a simple example of a perfect Pythagorean triangle. There are a total number of 14 of these racks included in this set.
The third phase of the build focuses on the tracks, comprising two identical elements.
The number of gears is impressive and a series of wedge belt wheels are also added at the bottom of the upper structure. These will eventually roll over the arches of new quarter-circle gear racks, even though this is more for support than for making the upper structure rotate freely and smoothly over the gear-racked circle.
The fifth phase of the build gives you all parts to build the small conveyor belt.
The build of the conveyor belt is straightforward and is set into motion using one of the vertical axles we built in the previous step. Also, it includes a distribution system formed with simple Technic beams, ensuring the soil and rocks transported end up on the right belt.
The most interesting part of this smaller conveyor belt is its manual movement. It can be rotated almost half a circle around two of the new arched gear racks and is operated with a knob at the bottom back of the model. It also includes a rather simple yet effective clutch system operated with a driving ring. This allows the smaller conveyor belt to have three positions. It can either rotated freely, be locked or remain stationary regardless of the position of the central structure: a neat feature that enhances the playability of this behemoth even further.
The bucket-wheel is turned by the end of the conveyor belt, although I had assumed it would be the other way around. Although this set-up is completely understandable from a design point of view, it comes with a downside. Because the wheel lacks direct actuation, it becomes rather feeble. It causes a jerky motion and is easily stopped by blockages or when lifting a heavy object.
Bags 7A Power Functions XL Motor, battery box and three bags of parts comprise stage seven of this lengthy construction process. The weight of the Power Functions provides a suitably heavy counterweight for the bucket-wheel.
Joining both parts of the arm and adding extra sturdiness with even more beams is a satisfying undertaking. When finished and mounted on the main construction, the attachment of the arm is surprisingly solid. Unexpectedly, it turns out that a simple pair of linear actuators are able to carry and move the entire arm. This is predominantly courtesy of a well-balanced design, so, definite kudos to Markus Kossmann, who is the lead designer of this set.
B-modelThe B-model, whose instructions can only be found online, is called a Mobile Aggregate Processing Plant and is about 88cm long.
This set is a remarkably good deal price-wise and an excellent parts pack for beginner LEGO Technic builders with a modest collection. I also applaud that the LEGO Technic team are trying to enter new terrain, by developing sets that are not yet another excavator or racecar. It certainly brings something new to their palette, and in size and extremities it will be a tough act to follow.
It is a fascinating and in some ways unusual build, resulting in a truly giant piece of mining equipment. Aside from the various functions I have described throughout this review there are a lot of fulfilling play features, including the addition of the white mining truck. However the main function, the scooping and transportation of dirt, only works well if you give it a hand; the bucket-wheel does not always move in a constant fashion and is jerky. Like the real thing, most of the other motorised functions are sluggish to the extreme but this merely emphasises the physical limits of how big a LEGO Technic set can become. Indeed, perhaps 42055 Bucket Wheel Excavator stretches the boundaries of what is possible with axles, gears and beams.
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