Friday, July 19, 2013

TBs TechReview 26 – 42009, Mobile Crane MK II

Set reference: 42009                                                                                                                                                               
Set name: Mobile Crane MK II
Theme: LEGO Technic
Release date: 2013.Aug

Number of parts: 2606 (plus a few spares)

LEGO Designer: Kossi (Markus Kossman)

Model under review: Main model
Weight: 2.490g (87.8 oz) - w/o batteries
Approximate set dimensions: Fully raised and extended boom, and outriggers
Length - 58,5cm (23.0")
Width - 26,4cm (10.2")
Height - 77,0cm (30.3")
Approximate box dimensions:
Length - 47,8cm (18.8")
Width - 57,8cm (22.8")
Height - 9,0cm (3.5")

Stickers: Yes
Building instructions: 6 booklets (84, 76, 84, 68, 36 and 84 pages): 1/6, 2/6, 3/6, 4/6, 5/6, 6/6
B-model: Reach Stacker and Truck - Building instructions available online only:
1/5, 2/5, 3/5, 4/5, 5/5

Recommended for ages: 11 - 16
Building difficulty level: High+
Estimated building time: 7h - 10h

Price range: 200€ aprox.
Price per part: 7,7 euro cents

Inventory (Bricklink): Link
Other user reviews (Brickset): Link

And here we're to review the biggest LEGO Technic set in 2013, the flagship as we use to call it.
This review was preceded by a few live building sessions, that were streamed online and you may have eventually followed. If it was not the case, you may still find some of recordings at TechnicBRICKs Live Stream Channel

This model has caused some expectations among the fans, because with over 2600 parts, it is the largest LEGO Technic set released so far. So everyone is curious to see how it performs as we have already seen some of the largest sets struggling to have its functions moving seamlessly.
This is also a model designed by one of the most known LEGO Technic designers, Markus Kossman, who had designed some of he most mythical sets in the recent past years, and also designed the 8421, Mobile Crane XL in 2005, with 1884 parts. Thus, the comparation is more than expectable and inevitable...
Because its predecessor was also designed by the same author, they have used a 'MK II' suffix to the name, which could have two readings - "Make II" like a remake of a former model, or "Markus Kossman II" in homage to the designer.

Whether this is just another LEGO Technic Mobile Crane, or it brings in fact some innovation relative to its ancestors, is something we are going to see along the following sections.

1. The package and contents

With the traditional large card box with lift-up cover, this set comes with the usual LEGO Technic flagship type box.
The front cover depicts the main model, its functions and other main information about the model like the number of parts, the PF elements included, etc.
Notice this model includes one PF L-motor, which is still a relative rare element because of the high demand from the Technic fans and due to the fact it is still not available as a spare part at

On the back, or bottom side, as usual we see the proposed B-model, which is a Reach or Container Stacker, plus a Truck to carry containers in this case.

Once opened the flip-up cover reveals in deeper detail the electrical functions of the model, with emphasis on the functions switch box and a numeric association with several illustrations showing the main functions of the model. Also other characteristics are shown, like manual functions and the dimensions of the model.

The electrical functions are:
  1. Lift of the crane boom
  2. Outriggers control (all 4 simultaneously), with auxiliary control lever on the right side of the truck chassis (switchable between extension/retraction of the outriggers and lower/raise of the outriggers feet)
  3. Lower/raise winch
  4. Extend/retract crane boom
Additionally we have some manual functions
  • 8 of 10 wheel steering via knob on the truck rear side
  • Continuous rotation of the crane superstructure
  • V8 fake engine with moving cylinders, as the truck rolls

The box is really heavy and full of content. You won't have any doubts about it once you open it. This must have been one of LEGO Technic boxes with least Billund air, released so far. And I only say "one of", because there are other in this semester as you will see in the next few days.
This is something expected as the box has the same size as from the 2012 flagship (9398) and almost twice the parts included. While this is more environment conscious you also fell better realizing you have paid a large amount of money, for a box full of LEGO, than one only half full.

As any other recent sets above a certain size, this one comes with the building instructions books and stickers sheet, protected with a cardboard inside a plastic back, so that they won't get damaged during transport as it often happened in the past.
There are 6 books included, 3 for the truck, 2 for the superstructure with cabin and 1 for the crane boom.
This bag also includes the string for the winch, unlike the small card box that uses to contain the string elements in LEGO sets.

Unlike previous sets that use to include the parts list in the end of the last book, this time this comes in the first pages of book 1, what seems to me a sensible measure.
Notice that from the 2606 parts included, nearly 1000 are pins and alike. But all know these always come in big proportion at LEGO Technic sets.

When taking the box contents out, we remain with a large bunch of polybags and some loose parts like tires and PF elements.

Bags got numbered (1 to 3) what should help building such a large set with huge partcount, unless you take prior special sorting measures to ease the building process - like I did.

2. The new parts

Before getting into the new parts, I'd like to highlight some facts.
This set comes with some parts that are not exactly new, but were introduced for the first time in sets from the 1H13. This is the case of new parts (1x5 thin liftarm with axle holes in the ends - 11418), or existing parts in never before released colors as seen from the picture on the left.
In the picture on the right side we can also see a couple of parts which are now released with this set, in new colors for the first time. It is the case of the 16L axle (50451) which was only available in white and now also in black (a much more common color for Technic axles) and the Axle and Pin Connector Perpendicular Triple (63869) now released in black for the first time.

As for really new parts, we have the new design for the 11x3 Technic panel, which we first saw in images from the LEGO MINDSTORMS EV3 Education Expansion kit (45560) in black - here it is released in yellow.
This part got extra pin holes for improved connectivity and sturdier constructions. These were added at its longest sides offering extra and new orientation connection points at specific points in this element.

And finally a new element which has been generating some hype - the 8 teeth sliding gear. This gear is based on the same design as the newest version of the standard 8 teeth gear (10928) which got wider teeth preventing it from sliding into the beams hole recession.

If you notice the details on the close-up photo, you should realize there are only two inner contact points instead of four in the regular 8 tooth gear. This alone with eventually a slightly larger inner radius, should allow for the gears to slide easily over an axle.

This sliding capability will offer new functional possibilities as we will see ahead in this review.

3. The parts assortment

Although this is not a very rich or even rich set in terms of included PF elements, perhaps because of its huge partcount and functions, this is a rich set in terms of parts diversity. Not a bit of everything is included in the assortment of course (like pneumatic or suspension specific elements), but still there is a large representation of current Technic elements. Besides the omnipresent beams, axles and pins, we get many other elements in reasonable amounts and diversity, from frames, panels, connectors, a huge set of gears and the two kinds of linear actuators available (2 large and 4 mini).

This is definitely a good set to start stocking your Technic elements, if you want to start building your own models and you can afford purchasing such large and expensive set. Despite expensive in overall, due to its huge partcount it is also a good deal in terms of price per part figures. Specially if you can wait and look for better deals or for the prices to start falling as the set gets closer to its retirement in a couple of years.

Additionally to the partlist print above, you can also see the full assortment listed here.

4. Building experience

This time because I was doing the live building streaming and also trying some time lapse video footage, I decide to not use the IKEA cutlery trays... but to sort all the parts over my workbench, hence the numbered polybags were not really useful as such.

And here we're, READY TO GO!!

We start with the first book of course, and with the chassis of the truck supporting the superstructure and crane.
At the end of the first book and after 75 steps, we are like this. The five axles and respective steering racks (4) are in place along with the basic switching box mechanism in the center, that will allow the selection of the two outrigger functions (extension/retraction and feet lower/raise).

We proceed into the second book until we get the basic chassis structure finished few steps ahead, before getting into the construction of the outriggers modules.

The outriggers are deployed as two distinct modules and here we have some intermediary photos from the rear outrigger module (top, bottom and top view again).

Interestingly the outrigger extension arms, are built with a double gear rack stacked setup. This allows for the exact height required to let it run perfectly tight inside the studless chassis structure. Also it provides a convenient top slot that provides a guiding line for an half pin which this way locks each outrigger arm in place and prevents it from getting out of the respective casing.

And then the rear outriggers module, gets properly attached into the rear section of the chassis.

In these photos you should finally see the red sliding 8 tooth gears in use. These allow to drive the outrigger feet descend/raise functions trough the black 16L axles, when this is the function selected, or allow the same axles to travel trough the same gears when we have selected the outriggers extension/retraction function.

Moving forward we also build the front outriggers module and attach it into the chassis.
The next step consists in guarantee that the front axle is well aligned with all the four rear axles. For that we are going to build an auxiliary beam structure to align the axles in place. This is the second time we use such procedure in the building of this model and the auxiliary structure is disassembled just after.

With this, we have now reached the end of book 2.

The model proceeds with some fairing, the fake engine behind the driver cabin and the construction of the cabin itself.
These constitute all the building steps from book 3, and let us with an almost 60cm length giant truck.

It was quite later that I've noticed that placed the side panels covering the engine, with the stickers upside down. How could one expect to avoid such small mistakes, if building, taking photos, doing a video live strea m of the process and talking at the same time...

We are now diving into the second part and start building the mobile crane superstructure.
The next two books cover the most complex part of the superstructure, with all the gearing from the model main switch box and the driving of the pair of large linear actuators that will sustain the crane boom.
This is where the PF L-motor comes in, to drive all the model's motorized functions, inclusive those laying in the trucks chassis underneath (the outriggers command). As usual this is achieved by routing a driving axle through the large turntable attached to the bottom of this structure and to the truck chassis.

Like what was done in the design of the 8043 Motorized Excavator, here the 20 tooth gears with pinhole (87407) are also mounted facing each other, thus forcing the Linear Actuators (LAs) to drift in opposite directions to compensate when the boom gets lifted and becoming out of phase.
Doing some calculations we can determine a total lag of about 250º or 7/10 of a turn. In a total of about 26,5 turns to fully extend a LA, this represents about 2,6%. This is a progressive lag that represents always the same percentage as the LAs extend, but over 40mm when they get fully extended, this represents a difference near to 1mm between the two LAs.
It might be not enough to stress the whole structure too much over the complete boom lift, although it looks still a technical design flaw.
Wondering if there is some reason for this design decision, like an intended design symmetry for aesthetics purposes, or instead no one realized on this detail once more.

Thanks to Mike Hatton (Parax), for preparing this excellent pictorial explanation.

But moving forward again... here we have the same structure after some fairing and getting the upper reel mechanism to wind the winch cable, the goes on the telescopic boom.

At the end off book 5, is when we get this structure ready, with the crane operator's cabin and battery box at counterweight place, attached to the truck chassis by fixing the large turntable on it.
You should realize on a small detail - the 8 tooth gear on a friction axle/pin, next to the large turntable, preventing the whole structure to freely rotate with minimum friction.

Getting into book 6, we start building the last element of this model - the telescopic boom and crane.

Below the inner boom assembly, with crane's second and third section, at retracted and extended positions.

This one goes inside the first and external section, which also provides the final look as it is seen from the outside. It is a remarkable step from the previous LEGO Technic mobile cranes, in terms of aesthetics, because of the use of the Technic panels as fairings. Only possible if building at a larger scale, as it is the case of this model.

Once assembled together, this is the final look of the three section telescopic boom, seen in different positions (fully retracted, half extended and fully extended).

The last steps consist in attaching the telescopic boom to the cabin structure providing the necessary gearing is put in place, passing the winch cable over the boom and around the winch wheel, and fixing the end.

Eventually you will end with something like this...

And I say "eventually", because I ended with this tremendous amount of spare parts...
Although it seems an increasing trend, I cannot stop thinking that eventually some may have been left behind during the building process.
Usually these are not extras required for the B-model.

The parts list indicates one 32L axle, which is used by the main model. Although there are included in the box. Assuming the B-model does not use both, which I really don't know but guess not, this is an weird part to be included among the spares as it is large enough for not being lost that easily.
Unless, I was a lucky bastard getting this as consequence from a virtually unique mistake from the sorting machines in the packaging line...

We're done with the building enterprise!

5. Functionality and playability

Before getting into the model's main functions I would like to focus on a few functional details and I'd start with the outriggers.
It is not the first time I see used into an official model, some friction blue axle/pins, while I'd expect the corresponding frictionless tan version. There are situations where the friction doesn't seem to be needed at all, and it just drains power from the overall function, which is a waste specially when this is motorized.
It seems to be the case again with the feet on the 42009 outriggers.

The blue axle/pins on the 2x4 L beam in the picture above, generate unnecessary friction at two points and there are four of these outrigger feet, moving simultaneously in the whole crane.

Adding to the fact that when I first tested the model with fresh charged batteries, this function seemed to be not working at all, makes me even more convict that the tan pins would have been a smarter choice. Maybe not a significant difference, but definitely an improvement even if a small one.
The feet were not moving at all, and the corresponding gears seemed to be stuck somewhere. Because I was building, while doing the live stream and speaking sometimes or getting distracted with the UStream chat, I immediately suspected that something might have went wrong during the building steps related with this function - it would be a nightmare to find in the end what may have went wrong... Although all my inspections didn't reveal anything wrong, and after some time slightly pushing gears here and there, it finally started to work progressively.
My conclusion was that the mechanism associated with these was almost in the limits of the L-motor strength and anything not put in its optimal place, could be enough to jeopardize the whole function. Hence I'd prefer to reduce friction in each feet, besides the small benefit it might constitute. Again, we must remember this is a function where the motor is in the upper structure, and driving a quad outrigger setup in the chassis of the truck, through the turntable connecting both structures.

My next remark goes for the cabin in the superstructure, from where the operator sits and commands the telescopic crane, winch movement, superstructure slew, etc.
This requires him to have big visibility on whats going on all the time, and often such cabins can be adjusted (raise and tilt) to facilitate such visibility.

On such a large model, I'd expect to have the possibility to make such adjustments to the cabin in the superstructure, even manually. Specially after having the possibility to tilt the cabin in the former 8053, but it is not the case here, where it is absolutely fixed.
I'd like to have seen a cabin that could tilt and lift a bit, even if has to be done manually.

Although we got opening doors and adjustable seats in the cabins. It was the minimum I'd say!

The hook used for the winch itself deserves some remarks. Also since the release of 8053 in 2010, LEGO seem to have abandoned the good old metallic hook (70496). The pulley used with that hook was its main problem IMO, because the string often moved out of the pulley too easily, requiring then one to disassemble it at put the string back in place.
By doing the hook out of other discrete Technic plastic elements also allows to build always in scale with the model and eventually to make a design that fits closer with the hooks used in real cranes. The pulley wheel (56902) used in these is also far better than the former one, because it has a much deeper slot where the string moves in.

The only drawback is that such hooks are likely not much heavy as the original was, thus causing less tension on the winch cable, when the crane is not lifting any payload.
This is something we really notice with this model, as LEGO went for a new type of string. It is really an high quality string, as it is made from a different material then the previous ones which, were made of some kind of softer fibbers. The string is also significantly thicker and one can notice the lack of tension too easily, while moving the winch upwards or downwards, if not loaded.

Another aspect related with the winch movement is that it does not move in synch with the telescopic boom when it is extending or retracting. This was a feature only seen in the old Mobile Crane XL from Markus (8421).
When extending the boom, more cable is needed and consequently the winch gets closer to the booms' tip, eventually getting stuck at that point. The opposite happens when retracting the boom, eventually leading the winch to hit the ground. To avoid such effects one should shift between the boom and the winch operation.
Don't think it has been the lack of power available from the L-motor that contributed for this design decision, so maybe we can wait for a MOD from someone, regarding this aspect.
Although this is not a big problem as a full extension or retraction from the boom, just displaces the winch about 11cm vertically, whereas the whole model it is 77cm high. One can perfectly plan the movements in advance if really concerned with this missing feature.
Also I was trying the 8421 again as I didn't remember exactly how this work, and realized the movements were not properly synch, but running simultaneously at quite different speeds. Hence the problem persists there and 42009 does not stay behind in this aspect!

Some have also mentioned about the manual slew of the superstructure, claiming for some motorization regarding this function.
Again I don't think it was the lack of power delivered by the L-motor, that prevented the used of this functionality, but eventually the need to keep with a 4-way switching box, thus avoiding the need to go for a larger one that certainly would require more space and elements into an already huge model.
Although older mobile cranes (8460/8431/8438) had this function controlled manually with a knob/wheel. It would have been great to see something in this direction, done with this large model too!

As for the motorized functions in this model, I found them all working pretty well, but really slow in most of the cases!
I'd say the only function that doesn't run that slow, is the outriggers extension/retraction. All the others take about 45'' to 60'' for the full movement amplitude (with rechargeable batteries), which is quite a lot of time. In the case of winch it even takes about 2'15'' from the top (extended boom) to the ground, or near 3' if we let the whole string unroll.
Although better to have these functions running slow then faulty! If we want to do a fair judgment, such kind of machinery in real life, also work at a very slow pace, then this toy is at least realistic in that regard.
The only function I think that should run definitely faster is the winch...

I'm also in believe the gearing ratios and the low speed choice for the functions, play a great role in reducing the velocity at which this model drains the batteries. After several days playing with it, taking video footage and exercising the functions to take many photos, it is still running as when I started playing with it.
Good work done here to save batteries, if it was done intentionally.

Nevertheless I must say the slow movements also have the advantage to make the functions to work really well, because there is enough torque available at the expenses of speed.
For instance the telescopic boom extension works flawlessly and without the "hiccups" we can observe on 8421. This is definitely achieved with the contribution of a great bracing done for the gear plus worm gear setup, at the top of the the boom, which guarantees that the mechanism never slips back.

Another great improvement in terms of playability compared to 8421 (the biggest Mobile Crane before 42009), is the fact that the boom is lifted mechanically (with a couple of large Linear Actuators) instead of a pneumatics circuit. In fact we notice the biggest advantage not exactly when it lifts but when it is lowered.
You certainly remember how abruptly the booms descends on 8421, unless you have a very precise handling of the respective control valve...
This is one of the cases where Linear Actuators have a huge advantage compared to pneumatic cylinders, despite they're not the better option in terms of realism.

In this model, if I have to use pneumatic cylinders, I'd have used them to control the outriggers feet, which would look realistic and faster...
Although we should not think this was a natural option for this model because of the impacts and consequences it would have on the design. The gearing is already available at the outriggers level, and with a small switch box we can also control the feet. It was also the right excuse to get the new 8 tooth red sliding gears.

A special note also goes for the easiness to replace the batteries. The battery box detaches really easily and you don't have to disassemble any surrounding parts to access the batteries compartment.
This was also a nice improvement when compared with 8421, which still used the old 9V battery box (2847c03), prior to the Power Functions era.

Although, I'd not go into the next topic without a negative remark, which I could have produced since the first day we got see the PF elements, but never did without a reason. "Easiness to replace batteries" is a way of saying...
In fact, IMO the actual PF Battery Box sucks! For those like me who use large capacity rechargeable batteries, these tend to be a bit fatter than most common batteries and this turns quite difficult to remove the last battery from this BB (the one lasting in the picture below).
I believe this element could be easily redesigned to avoid or at least to minimize this annoying problem!

Now about the steering and turning radius. Although I've not made any precise measurements, I estimate that 42009 has a turning radius of about 70cm, while 8421 turns with a minimum radius about 35cm, although the axles in this one kind of over steer a lot, making the turning of direction quite difficult (a more natural steering radius for this would be about 40-45cm).
We must realize that 42009 truck with its 5 axles, is quite longer then its predecessor (4 axles) and distance between axles is also longer. Hence the observations are quite within the expected.
42009 has a realistic and differentiated steering for each of its different axles. The center axle does not steer and the next ones immediately after and before turn 13º. The rear axis turn 17º and the front one turns 21º as it is the farther from the central axle. These differences seem very adequate for a natural and effortless steering.
All the steering axles turn with the same gearing ration combination, hence the differentiated steering angles are achieved through different length steering arms on each axle.

In the video below you can see a demonstration with most of the functions above mentioned.

And also my first serious timelapse experiment, with a few missing fragments.

Hope you enjoy the videos despite a bit tedious (eventually)...

One aspect you may have noticed in the video is that because the string and boom extension movements are not synch, I did switch between both movements a few times. Usually when extending the boom I need to lower the winch a bit to compensate the string length required for the boom extension, and when retracting the boom I need to raise the winch.
Although and once I've followed exactly the instruction steps provided, whenever I switch between both functions, I also need to reverse the polarity switch on the battery box, which is quite inconvenient... It would be easier if I just need to switch between functions using the lever on the switch box.
This could be easily fixed, if the string is winded on the reel, in opposite direction. It is not even need to disassemble anything to fix this. It is enough to lower the winch till the end and let it continue winding in the opposite direction, till the winch reaches the tip of the boom.

...And that's the time for a family photo, with some of the LEGO Technic Mobile Cranes, that I keep assembled and stored in the garage...

Love them all, but 42009 is definitely the best looking, most functional and most realistic one!

6. The B-model

As B-model for the 42009 Mobile Crane MK II, LEGO proposes something quite original in the LEGO Technic assortment, a Reach Stacker or Container Stacker.
In fact this set assortment of parts is so rich, that it was enough to build not only a Reach Stacker, but also a container and the truck where the stacker can pick/drop the cargo for transportation.

While this provides extra playability to the set and more specifically to the B-model, I would have preferred to improve the aesthetics of the stacker, sacrificing the transportation truck. I'm not sure whether this could have significantly improved the stacker itself... however I feel something should have been done differently on the stacker car to make it look nicer.

On the the other end, the then wheels used in the main model, are the exact number required to build a stacker with double wheels in the front axle (like the real ones) plus the truck. This way we shouldn't have a significant amount of parts left after building the alternate model.

Although I've not yet built this model, I'm already impressed with the functions and realism put on the spreader (the containers gripper mechanism).
Unfortunately the container is nothing more than a frame, but there were not enough panels in the set to build something different and even if it was, then the weight may turn it impractical to use with the model.

As far as it seems, the B-model should offer also a rich set of functions. After a glance I've identified at least these:
  • Stacker telescopic boom lift
  • Stacker telescopic boom extension
  • Spreader rotation
  • Container locking mechanism on the spreader
  • Steering of the rear axle on stacker
  • Truck 4WS via HOG
  • Passive container auto center function on truck
And I'm not sure whether the stacker cabin could be lifted or not, but it looks like it is.

    7. Final thoughts

    With five motorized functions, this is a major step forward relative to its ancestor 8421.
    As I've said earlier, 42009 looks nicer, it is a lot more realistic than the others and it works flawlessly, if you can live with its characteristic low speed.

    I became a fan of this model, and must confess it made me to look at 8421 with much different eyes than before - one of my favorite Technic models so far.

    I feel that virtually nothing was sacrificed in this model, that would fit into its already large size.
    As an example, the nice detail about the pulleys on the wheels, which the designers didn't want to sacrifice even though the large partcount of this model.

    Of course there are always a few things one could think to improve, like the motorization for the superstructure rotation, the cable synch with the telescopic boom function, the superstructure cabin lift, a different material for the rope, or some friction/frictionless pins here and there. Although it was a great pleasure to build this model and finally to have the privilege of playing with it!

    8. The Ratings

    After having wrote quite a lot about this model, there isn't much to add anymore...

    It offers a great value for money, specially in terms of perspectives for the price-per-part, and the playability offering of this model is definitely well above average!

    Although the still high ranks regarding innovation, these were the among the lowest ones as we always expect for more new parts specially in a vary large set such as this one. Also the mobile crane concept is something that have been visited quite often in terms of LEGO Technic sets, without much variance among them, besides the size and complexity. For example all them are yellow, if you understand what I mean...
    The set innovation could be even higher if we take the B-model into consideration. Although since it is not in the main scope of this review, a better rating for this category was also hindered.

    The set design details is among the best, however several potential for improvements have been suggested. 

       as value for the money
       for parts innovation
       for set innovation
       for set design
       for functionality and playability

    Overall rate: Recommended  

    This is a must have set for a LEGO Technic collector or anyone who ever wished to have 8421, but never had the chance to get one. For all the rest it is something really worth to buy, but those living with budget restrictions will likely need to pass this one.

    Finally the build of such a large model is always a risk for some, that may never finish it after long hours building marathons...

    Leg Godt!


    Parax said...

    Ugh.. I see they made the same mistake as on the 8043 Excavator. The gears to the pair of actuators should be on the same side not the opposite! As the boom goes up they should rotate the same way, not in different directions. (a 75 degree rise on one side is 75 degree fall on other, giving 150 degrees out of phase.)

    Eran1243 said...

    The extra 32L axle is given to everybody,probably because of how easy it is to accidently bend it.

    TechnicBRICKs said...


    You're right, they become out of phase!
    The involved gear ratio (20:12) on a ca. 75º boom rotation, would produce a total 250º lag.

    In a total of about 26,5 revolutions the LAs will rotate, this represents a difference of about 2,6%.
    It is not really noticeable among other LEGO Technic parts tolerances.
    Maybe that's the reason why the designers didn't care about it once more. Nevertheless technically this seems to point towards a design flaw.
    Wonder if there is some reason for this decision, like the design symmetry, or they just didn't realized on the difference???

    TechnicBRICKs said...

    I'll also add a reference to this aspect, in the review.

    Thanks for the heads-up Mike!

    Captainowie said...

    Wow, an impressive piece of work, both for the model and the review!

    You mentioned that the string was significantly thicker than in other models. I must confess that I was quite disappointed in the quality of the string that came with my Unimog model - the last time I had bought a model with string was the 8462 Tow Truck, whose string has a much more solid feel to it. Have you had anything to do with this older string and could comment on whether this is a move back to a better string, or is it a third type of string?

    Either way, I think I'll have to grab a copy of this one!


    TechnicBRICKs said...


    I think it is a third type and better type of string.
    Although I'm not totally satisfied with it.
    I'd prefer one of the same material but a bit thinner so it would get tensioned easier with light weights.

    In the case of 41999 (to discuss in the next review) I inclusive had difficulties to make it through the hook, because the string was supplied with burned tips, to avoid it to shred.
    Needed to cut and burn again after making the knot.

    Björn Leenen said...

    I was waiting for a review from you one this one. Last time was the Unimog review and you also posted the BI's, before Lgo gave them away ;) And here again, thank you for this.
    Of course the review counts too, because you wrote is very detailed. Thanks for this.

    rherberg said...

    Nice review (as always), can't wait to build it myself.

    btw, you can use the lid of the battery box to remove the battery pretty easily

    TechnicBRICKs said...


    That's what I do sometimes, however you can't apply much strength without damaging the lid.
    My problem is mainly with larger capacity rechargeable batteries, like Duracell 2650mAh (in the picture) or Energizer 2500mAh, which are a bit fatter and much more difficult to remove.
    As Jetro suggested in another thread, applying a few Gs does help, but still a a bit difficult to remove quite often.

    I'd really prefer a redesign, as I imagine the difficulty some kids may have with this.
    In their case, probably also with more common and thinner batteries. :P

    Allanp said...

    Thanks for the review, lots of lovely gear trains but this model is still not for me.

    Ryan said...

    Is the string the same as 8421? That was quite sturdy...

    And how can you change the direction of one of the 20 pin-holed gear? There is no way you can alter the base where the gear is mounted on...

    TechnicBRICKs said...


    I'm not sure about the original string on 8421 anymore. :P

    As for the 20t gear it is enough to rotate one of them 180º and mount it on the other side of the LA bracket.

    rm8 said...

    Thanks for review! Very detailed as always

    Alex Campos said...

    Thanks for the review, and the explanation on the symmetrical/asymmetrical 20T gears! I never understood what the problem was, since the gears spun freely on their axles and therefore (I thought) could be mounted either way, but I didn't take in consideration the fact that the angle changes.

    Regarding the string on the 8421, as far as I remember from the copy usually present on my LUG's events (which is Fernando's 8421, actually ;)) it is of the thin, fragile and easy-to-tangle variety.

    Blakbird said...

    It looks like the boom does not telescope nearly as much as it could. Some overlap is required for strength, but it looks like very much overlap is still present. What stops the telescoping boom from going farther? On the 8421, there were a couple of 1/2 pins that acted as stops. If you removed or moved these pins, you could get another 6-8 studs of extension without compromising strength.

    TechnicBRICKs said...


    It looks the boom could effectively have been made to extend a bit longer.
    There is a 1x2 thin liftarm blocking it intentionally (see on page 23 from book 6).
    Even the middle section could have been made longer, once there is free space available in the outer section, when fully retracted.
    However this relates directly with the length of the second section and I think the limitation is on the length of the strings with end studs used. Not so much options available in the assortment.

    Kenneth Westelinck said...

    Thank you for the review. To be able to have the gears on the same side, instead of opposite sides you _do_ need an additional part to accomplish this. You'll need a Liftarm 1 x 3 Thin.
    Don't believe me, try it :)

    Tom K said...

    This probably is not the best place to ask this, but I have a question on assembling this. I am stuck on a step. Can someone help me here or point me to a better forum??


    TechnicBRICKs said...

    @Tom Kunsman

    Maybe you can ask here, or then try EuroBricks.

    Mark Bellis said...

    Is it considered by TLG that there is no problem for the opposite-side bevel gears with the redesigned LAs?

    Unknown said...

    I have finished the truck assembly for this set and ran into an issue that I hope gets resolved when the motor is attached. Here is the issue. The outriggers extend and retract just fine with the main gear. However, they do not raise and lower when I turn that same gear with my finger. It seems as if there is a lot of tension on the gears throughout the entire assembly. Was this an issue for you on initial assembly? Did the issue correct itself when the motor assembly was attached? Thank you very much for the excellent review and any help you may be able to provide me with.

    TechnicBRICKs said...

    @Nicholas Hoelter

    I described a similar problem that happened to me, in the review.

    Read about, at "5. Functionality and playability"
    After the first image in the same section.

    rherberg said...

    I'm also building this one and I have something I noticed also in previous sets, different colours yellow in different parts. I have parts that are a lighter yellow than other other parts (It even seems to be of a cheaper plastic, more seethrough.

    Did you have the same problem? It is very noticable on the gearbox (see picture:

    and a bit harder (on a picture) with the panels(see picture:

    I only noticed it with yellow for the last year or so, also in non technic sets/parts). Maybe they're Chinese parts?

    TechnicBRICKs said...


    Yes I noticed that too.
    It is natural on some parts which are made from a different plastic, or some "difficult" colors.
    In such colors, production cost increases dramatically as you try to keep the color reproducibility within acceptable ranges.

    However this should not be the case of such common color as yellow...
    Hence I guess TLG is saving some money on the raw plastics to produce their parts, going to less accurate colors-

    rherberg said...

    I finished it last evening and I also have a 32L axle spare. Weird, because I also beleive it isn't used in the 2nd model (I skimmed through the manuals)

    Unknown said...

    I'm just asking to double check but to fix the linear actuator problem do I just reverse the set up for one of the gear mounts?

    TechnicBRICKs said...


    I've not tried it myself, but I'd say it is correct!

    Anonymous said...

    when im finishing my 42009, i will put a power function switch into the
    gear module.. to switch about forward and backward :)

    Unknown said...


    Just finished this model with my son. But there is one question that I hope can be answered in this group.

    It is about the operation of the two linear actuators for the boom. I've read some comments about the 20T gear should be on the same side, will that solve my problem, which is:

    When the boom is at the highest point or lowest, there is no clutch that stops the axles from turning, which makes the gears at the bottom of the actuators to "jump" over tooth's. Is this normal or any idea where we've done something wrong?

    TechnicBRICKs said...

    @Tor-Einar Pettersen


    Are you sure you see those gears "jumping".
    The internal LAs clutch should come into action before, hence the cracking sound you are hearing.

    Although I've not my model with me to confirm, at the moment.
    It is at exhibition in a shop at the moment, until beginning of next year.

    Unknown said...


    Thanks for the reply, I'm not so sure anymore, looks like the gears are not turning and the noise is coming from the LA actuators. So things might be normal. But I find the noise a bit high and sounds like the model is breaking up. The only negative thing I've found on this model.

    I can't see why they have not used a clutch on the transmission, but I suspect the boom might be to heavy for this.

    Thanks anyway for you reply :)

    Knutti said...

    Come on people....

    The LA actuators don't come out of phase. Please study the internal design and you will see my point, and as long you adjust (by turning the outer part) it has no concern if it's turned 180 degrees or not. This is PLAIN mechanics people :-)

    Unknown said...

    hi, I am starting to build my crane. just a thought would application of ceramic grease, like I do on my Taamiya RC cars, make the crane operate more efficiently?

    TechnicBRICKs said...

    @Sam Mad

    I don't know about ceramic greases, but generally would not mess LEGO with greases.

    Girildo said...

    Hi everyone.
    I just finished assembling the gearbox. I have a problem: I noticed that the bottom left gear (the one that serves to extend the boom) rotates even though it is not engaged. Is that normal (as I didn't mount the boom yet the gear isn't loaded in any way) or did I possibly make a mistake during the assembling.
    Thank in advance.

    Pedro Oliveira said...


    I follow your blog almost everyday because it's one of the best i've seen and because you are portuguese like myself.

    Can anyone tell me the normal period of sale to this set?
    Let me explain better, i want to buy this set but i'm saving money to do that and i'm afraid that the price rises when LEGO stops selling it!

    Thanks in advance for the answer!

    TechnicBRICKs said...

    Thanks for the praise Pedro.
    Unfortunately it is far the time when I wrote at TBs almost daily... :)

    Typically such flagship sets have been selling by LEGO for something between and 3 years.
    This set you're looking for was released in August 2013, so you're in the safe side for at least more than on year still.

    Pedro Oliveira said...

    Thanks for the quick answer Fernando.
    By the way do you think the price tag will drop? In amazon for instance! Or even in Lego Shop.

    TechnicBRICKs said...

    It may drop specially in the phase out period, but this of course not certain and depends also on your luck to catch the period, specially if it turns to be very short.
    Suddenly the product may become still listed but definitely not available anymore.
    Although specially on the Christmas period you may have the chance to find some good deals in certain store chains near you.

    Ludo said...

    Great review! You convinced me to buy the set :-)

    I was left with different spare parts: a bunch of small things like you, but instead of a 32L axle I finished with a 5L, 6L, 7L and two 8L axles left. (Adds up to 34L ;-) It made me seriously wonder if I hadn't forgotten something.

    While I agree that the model is indeed awesome (albeit a bit slow), I was really bothered by the instruction manuals, for two reasons. I had a problem discerning black from dark grey pieces; twice I had to disassemble part of the model to replace a black part with a dark grey part. But the more annoying was the sheer number of instructions: 70+ per booklet x 6 booklets = a lot. I was looking back at my instructions for 8880 (super car) and 8480 (space shuttle), and both needed only about 40 instructions for the whole model. (Maybe it has been like this for a while... the last set I bought before this one was the 8479 Barcode scanner truck ;-)

    TechnicBRICKs said...


    Indeed Tecnhic changed a lot since the old days and building instructions have like this for a long period.

    Many other things have changed as well which might have contributed to this - bigger models and change from studfull to studless construction.

    Still many AFOLs complain about the small steps used nowadays.

    Ken said...

    I am currently building the crane 42009 and I am in my last book. on page 57 step 39 can you show me in any way what and how the line that attaches to the 5 hole yellow piece in holes 2 and 4 goes? I have asked Lego for some direction and have really gotten nowhere with their help. In fact they had me going to step 57 in their last email. I need to know how this is to go so that I may move on from this step and onto step 40. Thank you in advance.

    Ken said...

    Hi Fernando,

    I am wondering if you can help me with step 39 on page 57 of book 6? I have been trying to figure out just how this line goes and what path it is to travel in order to perform the function it is designed to do. I have asked help of Lego Experts and I am not getting much help. They even directed me to step 57 as my answer. They then told me that it attaches to part in step 38. I know this however the question is the line that goes in holes 2 and 4 of the yellow piece is what I need help with as to how it is placed so that I can move to step 40 and beyond to finish this project. Do you have or can you provide any photo's as how line is to be routed? If anyone has any help they can offer I would be very grateful. Thank you in advance.

    Dieter_be said...

    i got this set last christmas. interestingly I had a similar amount of spare parts, but not the long axle, instead I have several smaller black and grey axles. (and trust me, I didn't forget any pieces while building the model ;-)
    Also i wonder what's the point of the extra wire. I have to agree with your point about the outrigger feet, why the friction pins... maybe it makes mechanical sense? One of my remarks about this kit is that in general everything is very sturdy, there are lots of reinforcements everywhere.. except the outrigger feet have a very minimal design where a lot of weight comes down on 2 pins. it looks flimsy, having an L-beam on both sides of each feet would make it sturdier. I also wonder if the gearbox really had to be as complicated as they made it, not that I mind much. This kit was my comeback after not having played in 15 years or so, I was happy to see some of the new stuff like the cog wheel that skips instead of blocking, the red sliding wheel, the adjustable coupling of cog wheels on the axles, etc.
    PS: great review!

    Dieter_be said...

    PS: I also wonder why the outrigger control switch is on the left side of the truck while the controls of the other axles are all on the right.
    when i'm using the various power functions this becomes annoying to go back and forth. since the base of the truck is so symmetrical, I think they could easily have moved the outrigger control to the other side.

    Unknown said...

    Step 39 miffed me also for a good long while. Finally I realized that the little black stud connected to the thread is actually two stubs connected in one. You have to separate them out and then the stud with the shorter free string goes on the left and the other on the right. Doesn't really matter much though whether left or right, The studs just need to hold the string there, that's it. Hope it helps someone else!

    ROLAND said...

    I'm half way done building this and it seems the front pair of actuators go down as the back pair go up. I double checked the instructions yet still they do the same. Do you remember if there's a mistake in the instructions?

    ROLAND said...

    p.s. I meant "outrigger feet" not actuators

    Jetro said...

    I remember having some issues with the outriggers working the opposite way they were expected to on one side of the crane. I solved the issue placing the tan single bevel 12t gears that are placed in the mini Linear Actuators on the other side opposite side of the black gear they mesh with on the locations that caused me trouble.

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