Conveyor belt
I have a big appeal to self unloaders. This started in my childhood when my father helped me to build a similar model after we saw
one on a LEGO show in 1987 here in The Netherlands. After the first large self unloader I built two more but the third one was
the best so far and had less malfunctions than the other ones. I broke it off already in 2005 because I needed the red pieces for
the large Mammoet truck. But a self unloader should be a standard in my collection an when I spoke to one of the Holwerda
brothers during the Mack & Special Transport Day I really thought I should pick it up again and it definitely should be their NL12. This time I
actually wanted to built a truck with a drawbar trailer but I couldn't find a suitable example (those are quite rare). The NL12 is an
unique truck of which only a few were sold in The Netherlands so why look further?
The tractor
The base for the new model what is ancestor of 1997. At the time I documented this truck by making instructions with
LeoCad.
But very quickly I saw the front axle was one stud too wide and the boogie could be much better detailed. So I did. The lift axle
works just like the real thing. Not only the back axle is lifted, the driven axle is pushed downwards to create more traction when
the truck is empty. From the front to the back the chassis has the same width and than it's very easy to make it rigid. Modern
chassis are wider at the front to house the engine. This wasn't the case with this NL12. The engine I built from scratch without
using any of the drawings I made in the late 90s. While searching on the internet I found quite a lot of pictures I could use and at
a hauler in my neighborhood I could have a look underneath the bonnet so I could see every detail. In 1997 I was less critical
than I am nowadays; I didn't use that much reference material and there was also less to be found. The last years I'm getting more
a more critical on my own work what I see I would like to build (actually must). Don't I have a picture of a certain detail I will search
for it. That is also time consuming but it's also part of the hobby.
The bonnet is better shaped. Did I work with steps of one studs 13 years earlier this time I did with halve studs. At the front the
bonnet is less wide than with the cab and you have to camouflage that somehow. The mudguards are also better shaped and
are closer to the real thing (the previous one were too low). For the mudguards underneath the cab I used the same arches. The
front grille is except from the logos 100% LEGOs without cutting LEGO parts. The grille itself is 8x10 studs and the Volvo logo is
just in the middle of it of a 2x2 tile. The grey frame I made with some SNOT techniques and with the very popular
'cheese slopes'
I made the outer part. Only this bonnet took me evenings to build and figure out but I'm more than satisfied with the result. And of course the bonnet can be
opened.
Did the '97 cab had the same width overall it had to be different now. The Scania LS111' cab is also
wedged and with this Volvo I had to do the same. The doors are wedged and are following the same line
as the bonnet. Another detail is the NL12's doors can be opened. But when the model was progressing it didn't seemed the doors could
be open again. Fortunately there is space enough between the mudguards to have a reasonable angle when they're open. The interior
is quite basic with a straight dashboard and steering console, two seats and a bed. The back of the cab is rounded
on the sides . I definitely wanted it to keep it like this however it would be camouflaged by the roof spoiler. I solved this by using one brick high
panels.
The roof spoiler is much better lined than its ancestor which had more or less a straight lined one with mainly 45 degrees slopes.
When the cab had its final shape two straight exhaust pipes had to be mounted. At first I made them like I did back in '97 but they
really didn't fit! Much too big! The new model is less hefty a smaller stacks will fit much better. But which parts are best to use? I knew the
Black Cat
contains some chrome parts for the exhausts but actually those
headlight parts
are much better! Only I didn't had sufficient of them in my collection and they were not that cheap via Bricklink. Anyhow just close your
eyes and order them. Now I have stacks of about 30 Euros each ...
The trailer
In a meanwhile I also started with the trailer. It's another one than the truck had when I built it in '97 but most people will only see the
difference in color. The new trailer is white and based on a tri-axle Bulthuis chassis. The body is built by
H.W. van der Peet & Zn.
of Nieuwkoop, The Netherlands. This time I wanted a complete new setup. The body have to be smooth which looks more realistic. A few years
earlier I bought about 1,000 pieces of 1x6 bricks, a very well basis of the body. The red frame I made of the pieces from the De Angelis dolly behind
the Mammoet concrete beam transport which I took apart.
The principle of the trailer is same as the previous ones. The conveyor is going from the front to the back of the trailer and is driven by one single
chain at the back. I used the same system with the Floor on the fifth wheel of the DAF 95XF of Van Keulen and it works properly. For the DAF I
used a double chain because I thought a single one would be far too weak. Because the real thing also has a single one I tried it this time and
on scale it also fits better.
The sloped parts inside the body are made of plates. It's less heavy and the angle more like the real
thing. And when you use plates you can also make a much more realistic tunnel above the conveyor with the help of
angle connectors.
For the tunnel I also used plates instead of slopes. Eventually I did this because I was short in grey slopes for a six studs wide tunnel while I put a
four studs wide one in the previous ones. Actually the conveyor should be fully covered by the tunnel while it's about five studs wide. The tunnel is
needed to lower the pressure on the conveyor and it now runs much better.
The conveyor is driven by the 9V 'RC motors' with a differential in between. Man, those things have much torque! They're so strong a really crushed
many LEGO parts. In the end reduction there is a worm screw and that one has to put it's energy in it somewhere. A worm screw isn't fixed on the
axle and will move itself. To prevent this I put the worm screw between two
double bevel gears
but this wasn't sufficient enough. With lots of force it pierced the gear into a Technic brick and at a certain moment it went even worse when it heated
up the end reduction and several LEGO parts were melted with a Technic brick! I never expected it would run
out like this but with about 18 kg of beans in the trailer lots of forces are put on its
drive train. With lots of trouble shooting I really had it on a certain moment and put the project aside. But realistic spoken I managed to build
something like this for three times already so why wouldn't I manage this time? After some thoughts I continued; what went wrong and why? What
would be then the right solution? To prevent the gears piercing into a Technic beam I had to replace them by something else. But by which LEGO
parts? You don't have much choice but the
metal Technic hooks
seemed to be parts I was looking for. Now I put the worm screw in between them and if this doesn't work I really don't know what to do then ...
Again a new experience but with lots of seriously damaged pieces I started with the finishing touch; the chassis, the axle, side bars etc. It all should
be on and in it. The terraces at the front and back of the body are wedged on both sides and the ladders I made of hoses and Minifig hands. It has
a much smoother look however the ladders aren't quite straight causes by the hoses.
As I've said the body can carry more than 18 kg of beams. It needs about ten minutes to unload itself. After finishing the trailer I had to remove some
aesthetic defects but the conveyor itself only broke once. This is mainly caused by small pieces of beams which are micronized while loading and
unloading the trailer. I have to take this for granted. But this trailer unload itself like the original; first the back part lowers, than the front section and
finally the middle section leaves the trailer.
For my current standard I built this model quite rapidly; I started in October 2009 and finished it in May 2010. In between I was also traveling for a
month so effectively I needed about half a year to build it. I'm very satisfied with the result and I think I will keep this one. I will definitely show it on
the event I'm taking part every year.
Video
Here's quite a long video of how the trailer operates.
