02 July 2021

LEGO® Technic designer interview: Samuel Tacchi & Milan Reindl reveal 42128 & 42129

Posted by Admin

The LEGO® Technic brand has just revealed more sets for the second half of 2021: the pneumatic-powered 42128 Heavy-duty Tow Truck and remote-control 42129 4x4 Mercedes-Benz Zetros Trial Truck.

Samuel Tacchi (pictured left) and Milan Reindl (right), two designers from The LEGO Group's Technic division, joined New Elementary's Zach and Caz (the palindrome team!) for a chat during the Recognised LEGO Fan Media Days about these two upcoming big rigs as well as Technic element design. The following transcript has been edited for clarity, readability and narrative flow.

New LEGO Technic 42128 Heavy-duty Tow Truck

Samuel Tacchi: The US tow truck is not motorized but it is pneumatic. You can lower the back and this is all powered by the hand pump here on the side. Here you can lift and lower the boom; you can also extend it. It's a mix of geared and pneumatic functions in this set which makes it very playable.

Caz Mockett:
What made you go down the pneumatic route for that set rather than more conventional gearing?

Samuel: I think it was the right time and the right model to bring back these pneumatics because it's such a great feeling to see the movement and the smoothness of the air. I think it's something great on a model like this so I think it was the right one to bring it back. 

Milan Reindl: There's parts of the community who love pneumatics there's parts of the community who just rely on motors and actuators. We need to cater for both these big groups of fans... and honestly I'm a big fan of pneumatics myself so I'm glad to see it back again after three years.

Zachary Hill: Does this truck's pneumatic system use any new elements?

Milan: These are all cylinders that we've used previously. The long, slim ones are from the Arocs, and the other thick one was used on the Arocs and as well on the Forest Machine before.

Caz: Are there any plans to have a set with pneumatics with a motorized pump rather than just a hand pump?

Milan: That could easily happen, yes. It happened in the past and I don't see why it shouldn't happen in the future again. 

Samuel: On this one it's fairly difficult to put a motor running the pump, because you see it's a very dense model. You can see there is barely any space to put any motor in it.

Samuel: It's a wonderful product because it comes with so many functions - we stopped counting them really! I'm demonstrating only half of it now, but you also have a third axle that goes up and down. It's something on the tow truck for when you're carrying heavy loads; you need a third axle to reach the floor for stability so it's in the set as well. Then you've got outriggers on the sides - they just pop out, and there are two at the back as well so there's a lot of playability around the back of the set. A lot of things are moving in the front, so you see the really authentic look of the US truck and you pop the hood. Inside there is a six cylinder in-line, and you see the pistons moving as well. That is a layout we used to have on the Corvette and other small cars, and I believe the Mack.

Milan: The Mack truck was the first one to introduce it.

Samuel: So this is actually the second truck to have those mini cylinders. Then you can pop open the doors in the front, and you can steer the wheels using the cog in the top of the cabin. So this set is a very dense American tow truck with full function at the back with lots of playability. Hats off to Markus Kossman who designed this set, which is genius, really. Also, the towing fork has a new 'flip-flop' beam.

Caz: Huzzah! We like you at New Elementary.

Milan: It's an 11-module length that's been used on this truck, on the back and the side. It helps make the structure a bit more solid so I think it's a great usage on this model.

LEGO® Technic 42128 Heavy-duty Tow Truck has 2017 pieces and is available 1 August 2021 priced 149.99 EUR / 139.99 GBP/ 269.99 AUD/ 149.99 USD/199.99 CAD. Please consider using our affiliate links, New Elementary may get a commission: USA LEGO Shop | Australia LEGO Shop | UK LEGO Shop/for Europe 'Change region'

New LEGO Technic 42129 4x4 Mercedes-Benz Zetros Trial Truck

Milan: Now let me present my latest baby which is the 4x4 Mercedes-Benz trial truck. This model - as you can see - is quite big, with a bright green back and a dark gray cab. You can open the doors on both sides and you can open the hood. There's some engine details and a spinning radiator fan, you can open the latch over here at the back as well, and you can take a look at the gearbox. There's suspension, live axles on both in the front and in the rear. There are some other authentic details like the air snorkel and the fire extinguishers, et cetera. We also have a rubber duck on the front!

Milan: Besides all these features, it can drive because this is the totally opposite side of our portfolio from the tow truck. The tow truck is purely manual, while this is mainly remote control. You can still steer while climbing up. To talk a little bit about how it drives, you can maybe see at the bottom there are two large motors that are hard-coupled to a single drive train. That's the main reason why it has so much power to climb steep slopes, plus we have the planetary hubs behind each of the wheels which slow down the drive train even more. It's reduced more than five times to one so you gain even more torque, and there's one motor for steering. There's one more motor that does this funny clicking sound, and that's the function that we've never done in Technic before: a remote-control differential lock. So whenever your truck loses traction on any surface that is a little bit slippery or uneven, we just push the button in the app, and the central differential and a different differential in the rear axle get locked at the same time. Afterwards, constant, continuous distribution of power goes to all four wheels.

Milan: Besides that we have some new elements as well, you probably noticed we have a new tractor tire that is smaller than the one from XERION from 2016. If you want to build a classic tractor that has two sizes of the wheels, this is the perfect tire for the front wheels. We do have some parts in new colors: the small 3x7 panel and the toggle joint are in dark gray and the 2x3 panel extension that we just recently introduced in the first half year assortment comes in dark grey too. We have a brand new Mercedes star deco on the shield, and there's a lightsaber in dark gray as well.

Samuel: There's four lightsabers!  

[Editor's note: these are very expensive currently on the secondary market, having only appeared in a few sets before disappearing in 2008.]

Milan: The most important functional part is this universal joint that spins around and you can actually slide it on the cross axle without friction. So this is the perfect part for anyone who wants to build and create offroad vehicles, trial trucks, 4x4s and whatnot. If you have suspension with high travel, you need to compensate for the drive axle that's becoming shorter or longer. This element is tremendously simplifying this because - while you can build something similar - it becomes cumbersome, not very reliable and takes too much space. So this element will be something that hopefully the fans will appreciate.

Caz: To build something like that is normally at least three modules wide, right?

Milan: Yeah, if you want to build it, it's at least three modules wide and this is just slightly over one module in the thickness just around the ball joint.

Zach: And how long is that new U-joint piece?

Milan: It's five modules in total length, and the pocket is about three and a half. Basically two modules of free movement of the axle without worrying about it falling out. And then, we talked already about the flip-flop beam; the 11-module flip-flop beams are inside this set. This regular beam next to it is just representative of the bright green color that I'm bringing back for the rear of the truck.

Caz: We frequently read complaints about certain colors, like Bright Green and Olive Green, being used in sets because the possibility to create MOCs with these colors is limited. Do you think it's an actual issue and are you actively trying to change this?

Milan: We are always trying to make the fans happy and we listen to what you post online. We look for your comments, and if it makes sense for any Technic model we always try to bring more elements in those colors back so you can enhance the family of the panels and beams that you already have to open up for creating more of your own MOCs.

Zach: Going back to new sliding parts, I'm reminded of the new thinner springs (65151) that are in the Ducati Panigale. Was that part designed to fit more easily within that space of one module since other springs tend to be a bit thicker?

Samuel: I think for that model in particular, we were struggling with the space of the suspension in the front because it's so narrow and so compact as a build. So it was a good moment to introduce a new shock, which is a bit more stable than the previous one and it takes less space. So we had everything greenlit to develop certain elements like that for these motorbikes. 

Milan: And as well I think the building interface of it is much better because you have holes in two directions so it's easier to lock inside the front fork.

Zach: Do you know what quantities of the new elements are included in each set?

Milan: I believe for the universal joints, there are three in the truck. There's plenty of the 11 module flip-flop beams and there's at least three of the dark gray panels. That's just looking at the model, what I can see right now. There's four tires. 

Caz: That's good!

Caz: Going forward are we to expect lots of little rubber ducks in future Technic sets?

Milan: Whatever is necessary will appear there. This is for the trial truck community - they always put fire extinguishers on the side, loads of sponsors everywhere around the truck, and they always put a little mascot on the front bumper or the bonnet no matter if it's a teddy bear or rubber duck. Since we already had them it seemed like a nice homage, but does something different - an animal in a Technic vehicle.

Available to pre-order now, LEGO® Technic 42129 4x4 Mercedes-Benz Zetros Trial Truck has 2110 pieces and is released on 1 August 2021 priced 299.99 EUR/ 274.99 GBP/499.99 AUD/299.99 USD/399.99 CAD. Please consider using our affiliate links, New Elementary may get a commission: USA LEGO Shop | Australia LEGO Shop | UK LEGO Shop/for Europe 'Change region'

The LEGO Technic team answer 2021 element design questions

Caz: Other parts introduced this year are two rather simple panels: the curved 2x3 (71708) and flat 3x7 (71709). Were these panels designed recently or have they been sitting in a drawer for years, waiting for the right opportunity?

Samuel: The 3x7 has been around for quite a while if I remember well. The 2x3 panel extension, not that long.

Milan: Not for so long but it is fun, it is much easier. 

Samuel: Once again, when we had the opportunity to have it in a set, we took it.

Milan: And as soon as you introduce that part, you know how universally usable it is actually, because pretty much all the models are using it across the portfolio right now.

Caz: It's got one cross hole as an attachment point, why is that? Did you make any prototypes with only pin holes for the 2x3 part?

Milan: At one point we were just playing with the position of the cross hole… we wanted a cross hole since it's just a single module thick part. Locking it in a structure needs to be somehow possible, and this is the easiest way to do: just have a cross hole somewhere. We were afterwards just playing with the position of the cross holes from different corners or moving it alongside, and yeah, the corner at the heel is probably the best.

Caz: What led you to the development of the versatile flip-flop beam (the 15-module part 71710 and now this new 11-module)? Were there any challenges that prevented you from introducing flip flop beams earlier?

Samuel: Honestly, those elements were designed ages ago, it just wasn't the right time. They didn't fit within the frame and there were some small production issues. So now, we could release them without any problems and we are going to continue extending the family hopefully.

Caz: Excellent. That's great news. The summer Friends sets included a new Technic ring piece 11 modules in diameter. Was it created for Technic and then Friends happened to issue it first, or the other way around?

Milan: It was created by the Friends team and they afterwards came around and showed it to us to see if it could be potentially usable for us, but it's their own element.

Caz: Does that happen very often with elements?

Milan: More often than before. The Technic interface is finding its way into a lot more elements across the company, which is great for us.

Zach: I've never understood why there was such a divide. I mean, we've recently seen more sets having a Technic frame, but being sold as a System set, is that something that the Technic team is involved in? Or is it something that others are doing of their own volition, using your parts?

Samuel: They are using our parts to improve their model, in a way, and then showing off a bit more function and things moving around. We are good at it so we are here to help them really get it right - to help them get the right 'mood' with Technic because sometimes it's very difficult to understand how it works and how it's going to be installed in sets.

Milan: I think partially it comes from the fact that Technic, especially the studless form of it, is way more three-dimensional, way more lightweight, and allows you to build more rigid and solid structures very simply and very easily. With bricks you need to insulate everything and sandwich it between several plates. Just use one Technic frame and afterwards you can just extend it to have a solid structure for vehicles, spaceships, whatever you need.

Caz: Did the inception of Powered UP and Control+ change the way you approach motorized models at all?

Samuel: I would say yes because it brings us a new layer of authenticity to the model. We have one Powered UP model with us today. I think it's a good thing to add on top of a LEGO Technic model, and the app allows us a bit more freedom creating new things, having more motorized function in one set without having the control to be huge as a plate. So I think it's a very versatile way to approach the future of powered models. 

Milan: Right, it's basically an upgrade of the platform from Power Functions. It was super simple to start but on the other hand, I personally don't like how the infrared interacts during sunlight. This is so much better because you can stand 20 meters away and the model still keeps going while you're touching the screen of your phone, which is quite amazing. With the accelerometer built in our Smart Hub, you can do so much more and you can use it for powerful programming stuff which changes the behavior of the model, which was not possible before. Plus since we have the tacho readers in our large and XL motors, it allows us to do a lot more precise control compared to Power Functions. 

Caz: Thank you very much chaps for talking to us, we really enjoyed it.

New Elementary will soon be exploring these two trucks for a detailed look at the new parts Milan and Samuel shared with us in this chat. We sincerely thank them for their time and the efforts of the AFOLET team in organising the interview. Are you looking forward to these trucks as much as we are?


LEGO® Technic 42128 Heavy-duty Tow Truck has 2017 pieces and is available 1 August 2021 priced 149.99 EUR / 139.99 GBP/ 269.99 AUD/ 149.99 USD/199.99 CAD. Please consider using our affiliate links, New Elementary may get a commission: USA LEGO Shop | Australia LEGO Shop | UK LEGO Shop/for Europe 'Change region'.


LEGO® Technic 42129 4x4 Mercedes-Benz Zetros Trial Truck has 2110 pieces and is available to pre-order now in advance of release on 1 August 2021 priced 299.99 EUR/ 274.99 GBP/499.99 AUD/299.99 USD/399.99 CAD. Please consider using our affiliate links, New Elementary may get a commission: USA LEGO Shop | Australia LEGO Shop | UK LEGO Shop/for Europe 'Change region'.

READ MORE: All the new LEGO® pieces released in July 2021 in a handy list

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  1. Very good interview!

    I'll confess, my interest in Technic has decreased somewhat following the end of the rebooted Bionicle theme. As more of a fan of sci-fi and fantasy than real-world vehicles, a lot of my interest in Technic was related to wanting to make creative functions for creature or vehicle builds in that theme. But I still appreciate seeing where the theme is going and what sorts of new parts are being introduced. If nothing else, it helps prepare me for when some of those parts occasionally find their way into themes I do collect and build in like Ninjago and Monkie Kid.

    1. It's an exciting theme for mechanical functions, but there is something special about doing them in a fantasy setting like Bionicle. I'm digging how function-dense these trucks are - I wouldn't be interested if they didn't have creative recreations of their real-world capabilities.

  2. Looking forward to a closer look at that new universal joint. Can't tell much from the picture.

    1. Milan says it's very useful, and as someone who's built cars only to have their half-shaft fall out of a U-joint, I'm thinking it will be too. I'll be sure to do a close examination in the upcoming reviews of these sets.

    2. Agreed! And I think I'm understanding that it's not really the U-joint that's interesting, it's the integrated slip joint that is the real star of the show! Up to now if you need a slip joint it's either a huge assembly or you just do without and rely on the looseness of your tolerances to make it work

  3. If they so choose to, those designers could use the new ring piece as a case for a ball-bearing system. Ball bearings reduce friction overall and allow LEGO Technic axles to spin more freely, so I can definitely see many practical applications for such a system. https://www.youtube.com/watch?v=omRAf5kvYDY

  4. What would you have? A ball and socket with bearings somehow "stitched in" or "in built?" You would have to incorporate a housing or casing over an existing joint. That begins to defeat the purpose of LEGO, doesn't it?

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