Technic

Cement Mixer

The one Technic truck where the drum actually spins concrete out the back.

Brick Rated Score

3.9/5

Set 42112 · 2020

Pieces1,161

Minifigsn/a

Year2020

Set number42112

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The verdict

This one surprised me.

It's a mid-size Technic build that ends up being weirdly satisfying to fiddle with, because that big drum has an Archimedes' screw hidden inside that genuinely churns the little concrete bricks and spits them out when you spin it the other way. It's not the flashiest set on the shelf, and the giant purpose-made drum mold will annoy the purists, but the working functions punch above the price. If you like trucks that actually do the thing they're modeled on, you'll get a real kick out of this.

Best for: Technic fans who want working functions without a supercar price tag

The full review

Some sets win you over with looks and some win you over with a trick, and the Cement Mixer is firmly in the second camp. On the shelf it's a tidy, believable model of the kind of concrete truck you sit behind at a red light and never think twice about. Pick it up and start turning things, though, and it comes alive. This LEGO® set drops 100 little 1x1 bricks into the drum as your load of concrete, and the whole point is watching them tumble, mix, and then pour out the back chute. It's the sort of set that makes you keep spinning the crank long after the build is done, which is honestly the best compliment I can give a Technic model this size.

The clever bit is inside the drum. LEGO made a brand new two-piece mold for this truck, and tucked an Archimedes' screw along the inner wall. Spin it clockwise and your concrete stays put, spin it the other way and the screw walks everything up and out through the funnel. There's a three-mode switch on the chassis too, so you can have the drum turn automatically as you roll the truck along, leave it in neutral, or drive it by hand with a crank. For a set with no motor and no batteries, that's a lot of genuine mechanical play.

Now the caveats, because they're real. That gorgeous drum is one enormous purpose-made part, and if your idea of Technic is engineering a shape out of beams and panels, a pre-formed cylinder is going to feel like a shortcut. Plenty of builders grumbled about exactly that. The steering also runs off a bright yellow Technic rod poking up behind the cab, which works fine but looks a bit silly next to how carefully the rest of the truck is detailed. And at its original 120 dollars for 1,161 pieces, it was never a bargain-bin part count. If you came purely for the fake V8 in the cab and the piston action, that's nice but it's not the reason to buy this. The reason is the drum. If you want a model truck that performs its actual job on your desk, this delivers, and the working functions are genuinely fun to demonstrate. If you'd rather solve a big mechanical puzzle or you're chasing raw parts value, one of the beam-heavy Technic sets will make you happier. For everyone in between, it's an easy set to enjoy, especially now that it's retired and the price has crept up on the resale market.

It landed a 3.9 community average on Brickset, and after playing with it I think that's about right. It's a very good set with one or two honest quirks, not an all-timer, and it knows exactly what it wants to be.

The parts story

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

The build splits into two instruction books, and here's the fun quirk: by the end of book one, everything mechanical is already done. The chassis, the fake inline engine with its moving pistons behind the cab, the gearbox, the steering, even the wheels are all on before you're halfway through. That's backwards from most sets, where the tires are the triumphant final click, and it felt a little odd to have them on so early. Book two is mostly the cab bodywork and building up the drum and its support frame. None of it is hard. The instructions are clean and the pace is gentle, so it's a relaxed few hours rather than a head-scratcher.

The star part is obviously that brand new mixer drum, molded in two halves with the Archimedes' screw built into the inside wall. It's the piece that makes the whole set possible, and you won't find it anywhere else. Beyond that you get a solid pile of useful Technic staples: eight tires, a proper little gearbox with the three-position selector, gray panels for the cab, and 100 of those 1x1 concrete bricks that are handy for all sorts of things later. At 1,161 pieces for 120 dollars it wasn't a part-count champion, and a chunk of the bulk is that one big drum, so buy it for the functions rather than the brick haul. What you're really paying for is a mechanism that works, and on that front it earns its keep.

Fun facts

01LEGO created a brand new mixer drum mold just for this set, split into two halves with an Archimedes' screw running along the inside so it can pull the concrete in or push it out depending on which way you spin it.
02The set ships with 100 little 1x1 bricks that stand in for the concrete, so you actually have a load to churn and pour rather than an empty drum.
03There's no motor anywhere in the box, yet the drum still turns automatically thanks to a gear that drives off the wheels as you push the truck along.
04Released in August 2020 and retired in November 2021, it had a short life on shelves, and sealed copies have since climbed well above the original 120 dollar price.