Technic

Mobile Crane

A handsome yellow crane that looks the part and builds like a proper Technic set.

Brick Rated Score

3.8/5

Set 42108 · 2020

Pieces1,292

Minifigsn/a

Year2020

Set number42108

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The verdict

This one is honestly lovely to look at, all classic black and yellow with a boom that stretches to about 30 inches once you extend it.

The functions are all hand cranked, which I actually prefer because you get to watch every gear do its job. It won't wow you with a motor or a gearbox, and the boom is genuinely too heavy for its own base, but as a mid weight build it's warm and satisfying. If you want a good looking crane you can play with, it delivers.

Best for: Technic fans who want a good looking hand cranked crane without a huge price or a motor

The full review

What it is

The LEGO® Technic 42108 Mobile Crane is the kind of set that wins you over the moment the boom is finished and you crank it up to full height. It's 1,292 pieces in that classic construction yellow and black, and the finished thing stands tall and looks genuinely like a real mobile crane you'd see parked on a job site. This is a hand cranked model, no motor, no batteries, no gearbox, and I mean that as a compliment. There's something honest about turning a wheel and watching the linear actuator push the boom skyward while the gears click along. You feel connected to what's happening in a way you just don't when you flip a switch and walk away. It's got 8-wheel steering, two cabins, four outriggers, and a telescopic arm that extends out to around 30 inches. For a set that launched at 99.99 dollars, that's a lot of proper Technic going on.

The catch

Now for the honest bits, because there are a few and builders have been vocal about them. The big one is balance. That gorgeous long boom is heavier than the chassis can really cope with, so at certain angles the whole crane will tip forward and topple, which is exactly the moment you were hoping to admire your work. The outriggers are supposed to steady it, but they're mostly decorative here, and the front pair is the real headache. The rear ones extend nicely with little gears, but the front two have no gears, no handles, and no hooks, so you're left tugging them out by hand with a red pin, and it's more fiddly than it should be. On top of that, raising the boom takes roughly 60 turns of the actuator, so patience is part of the deal. And the only cargo it's really built to lift is the buildable pillar that comes in the box. It scored 3.9 out of 5 on Brickset, which feels about right, a solid set with a couple of real flaws rather than a knockout.

Who it's for

So who should grab this one? If you love Technic for the mechanics and you want a big, good looking crane that you operate entirely by hand, you'll get a lot of joy out of it, especially as a step up from the smaller sets before you tackle the giant flagships. It's approachable enough for a newer Technic builder but meaty enough to keep you busy for a good few hours. If you're chasing motorized play or you want something your kids can bash around without it tipping over constantly, this probably isn't the one for you. But taken for what it is, a handsome, mechanical, hands on crane, it's an easy set to be fond of, flaws and all.

The parts story

What the build is actually like, and the pieces worth knowing about.

The build breaks down into a satisfying rhythm. You start with a fairly simple chassis, since there's no gearbox or engine to wrestle with, and get the 8-wheel steering sorted early. Then you work up through the rotating superstructure and the two cabins before the whole thing culminates in the boom assembly, which is easily the best part. That last stage brings together a handful of gears and a string to run the winch, plus the linear actuators that do the lifting. Because it's all manual, the engineering is right there in front of you the entire time, and following how the drive trains connect is genuinely more engaging than pushing buttons. It's a mid weight build, challenging enough to feel like an accomplishment without ever tying you in knots.

On the parts front, there are a couple of things Technic fans will care about. The star is the new extra-long linear actuator, which at the time had only appeared in the much pricier 42100 Liebherr R 9800 excavator, so getting it in a 100 dollar set was a nice win. There's also a curved Technic panel in a color that had previously only shown up in the older 42009 Mobile Crane MK II, so it's a welcome recolor for anyone parts building. Add in a big pile of that construction yellow, all the pins, gears, and the panels that give the crane its clean shell, and the 1,292 pieces feel well spent. It's not a set stuffed with brand new molds, but the parts that matter here are the useful, reusable kind.

Fun facts

01The boom extends to roughly 30 inches (78cm) when fully deployed, which is a huge reach for a set of this size.
02The 42108 is entirely hand operated with no motor, gearbox, or batteries, so every function runs off cranks and gears you turn yourself.
03It carried the new extra-long linear actuator that had previously only appeared in the far more expensive 42100 Liebherr R 9800 excavator.
04Raising the boom to full height takes about 60 turns of the actuator, which several reviewers clocked as a real test of patience.