A few years I had the idea to build a mobile crane, but it had never came that far. I had the idea already in spring 1996. During the
Modelshow Europe I bought a number of photo's of a Gottwald AK 850 of the
company. I was very enthausiastic, but because you have to put a lot of time in such a model, I postponed it constantly. Begin
1998 I cut the knot and once again I bought some photo's. But this time of another crane, namely the Liebherr LTM1800/LG1550.
I had built a certain crane three years before than already, but I was not satisfied about several things. That is why I have decided to
build the same crane, but then one which could do everything which is possible to do with it. The crane that I have built three years
earlier was off the same type, but certain things were built from my own inspiration.
The Liebherr LTM1800/LG1550 is one of the biggest mobile crane which exist, with its lifting capacity of 800 tonnes and 184
metres height with a main boom and adjustable jib. It can work with two beams: a latice boom construction or a telescopic boom.
For travel the telescopic boom is removed and loaded on to a semi-trailer. This means the LTM1800 is then under the maximum
weight limit for road travel. The telescopic variant is typed as the LTM1800. I have built the other version: the LG1550. When this
crane has to turn out with its total equipment, about 22 semi-lowloader trucks are needed to transport all the beams and necessary
The LG1550 can be set up in several configurations, from a light boom for the hoisting of not to heavy weights to a heavy equipment
for heavy weights. The boom height varies from 21 metres to a maximum height of about 184 metres. My aim was to build the crane
in the SDW-configuration, a main boom, a adjustable jib and a superlift. The maximum height would be about four metres. Rather high for
a plastic crane.
The truck chassis
The truck chassis is the driven part of the crane. This crane has eight axles from which six are steered. Two axles are driven and the
crane can drive with the help of one 12 volt motor. The several steered axles have another wheel outcome, so they will prevent that
the wheels would wring. Axles 1 - 4 are connected together. Both rear axles are steered seperately by the spare wheel on the back
of the truck chassis.
Driver's cab and transmission
The driver's cab is provided with a complete interior. The seats are adjustable and the steering wheel turns when the truck is taking a
corner. The gearbox comes straight from
the TECHNIC Super Car. But my version is more compact because the space at the front is limited. Further it works just like the one
from the Super Car, it has four synchronised gears forward.
The engine block
Above the first axles houses a V12 engine with moving pistons. The engine block is just an extended version of the one from
but have I put four more cylinders on it. It is just a standard engine block, because I did not exactly knew how it looks like. You
can hardly see it on the pictures and because I gave the strenght of the chassis more priority above the accurancy, I built the
engine from my own inspiration. The engine is driven by a 9 volt motor which is connected to the Barcode unit. When the truck
drives, the cylinders are moving. You can determine the speed of moving by shifting the gearbox.
During the construction of the undercarriage I had the idea to put a real engine sound in it. I had bought the Barcode Truck a few
Just before axle 5 and behind axle 6 there are sensors.
When the crane drives forward a clump hits the sensor. To provide keep turning the motor, I have put a white 24 tooth gear on the
axle of the clumb. This is also concerns the second sensor.The Barcode unit is placed above axle 3 and 4, just behind the engine block.
One part of the crane which is very difficult to build, is an electrical driven turntable. Many people could not manage to construct
a well drive to slew such a big crane. When I finished the largest part of the crane towards the end of June 1998, I started to test
the crane in the backyard on a beautiful midsummer day. The boom was ready and I was curious if the crane would hold the weight.
It proved the necessary had to be changed in the drive of the turntable. The superstructure shocked namely when it turned. The
drive exist of two layers. In the first layer I changed a couple of gears and I renewed the whole second layer. In the 'old version' of
the turntable the where still some 48-tooth gears, which where put horizontally in the drive. The actual turntable was connected to the
drive with 8-tooth gears, like the crane in
the Technic Cotrol Centre. I was not very satisfied with this construction and it also was the main cause that the crane shocked
during slewing the superstructure. Moreover some 8-tooth gears broke several times. I have solved this problem to connect
wormscrews directly to the turntable. This intervention was a whole improvement, now the turntable hardly shocks, even with such
a heavy superstructure as on this crane.
The stabilization of the crane occurs automaticly. Behind the drive of the turntable I have put a compressor which is driven by a 9 volt
motor. This compressor is connected to four pneumatic switches to swing out the outriggers. It is a sort of a scissors system. The
outriggers are also extendible. There is a 4,5 volt motor
in each outrigger. The two front outriggers are not slided in completely because of the distance between the second and third axle.
Through that it was possible to create a gear construction to extend the outriggers. Both back outriggers have also 4.5 volt
motors, but I have also put a small round reduction unit in it. Because these outriggers are slided in completed during transport, there
was not much room left to put a drive in it. I have solved this to assemble the motor in the turning point of the outriggers, so they can
slide in completely. The crane is stabilized in a cross. The stabilization base is 1.2 metres by 1.2 metres. The crane is in such a way
stabilized that the wheels comes off the ground. This is also in real, so I wanted to try this also and I have managed it.
The finishing touch
To conclude the finishing touch of the truck chassis followed. Several things where put on it like mirrors, width poles,
lenght and width lights, fuel tanks, a spare wheel etc. I always try to build a model as precise as possible, the model must be a
well likeness. The deco's where put on it in a later phase.
Building the truck chassis was not too difficult. The chassis was very easy to build. The only part which has cost me a lot of time was
constructing a powerfull drive to drive the chassis electrical. A second part which was not easy where
the swing out stabilizers. I have used several constructions, but I was not satisfied with all of them. Finally I found a well solution.
About the turntable I did not have racked my brains over. It took me about 70 hours to build the truck chassis.
The superstructure was the most difficult, but interested part to build. The room in the superstructure was limited, because
nine motors + drives had to be placed in it. Several times I have changed the lot and broke it off, because it did not agreed. Or
everything had to be make place for another drive because there was no space left.
There are nine motors placed in the superstructure, four of 12V and five of 4.5V. The serves for:
winch 1: hoist drum (1 x 4.5V)|
winch 2: hoist drum (1 x 4.5V)|
winch 3: luffing the main boom or superlift (2 x 12V)|
winch 4: A-bracket (2 x 12V)|
to swing the operator's cab (4.5V)|
the winch on the front (4.5V)|
the drive of the engine block (4.5V)|
The drives are built straight above each other, there was not too much space left. Because I didn't use the front winch (no. 6 from the
table), I have used a square reduction unit as a drive. These
reduction units are not strong entirely, but for such occasions I can use them. For the swinging mechanism of the operator's cab I
have also used a reduction unit, a round one in this case. All winches are driven separately, the drives are underneath the drums
itself. For the drives I have chosen for the old type of LEGO motors of 4.5 and 12 volt. I have done this because they are more compact
than the later 9 volt motors. And, by the way, it is also possible to shorten the leads and you can thread them through Technic beams.
The first two winches are driven by 4.5 volt motors. This is more than enough because these winches serves for raising of lowering the
hook and as the model will not lift heavy loads, it doesn't need more powerfull motors. Both other winches, for luffing the boom and luffing
the superlift and/or fly jib, are driven by two 12 volt motors each. The motors of each drive are connected together with a differential
so the drive has more power. Designing and constructing a drive is not an easy job. As usual you never manage to build such
things in one time and It also must be powerfull enough. The drives fits perfect in the superstructure and they work also very well.
When the drives where finished, I started to turn all the cables into the crane. Because black braided ropes are hard to find, I
have chosen for white rope with a thickness of 2 mm. Because it is very thick, it rolls perfectly on the drum. Per drum I needed
about one hour to turn the cables on it! There is an alumium tube in each drum. I have chosen for this solution because they are flat.
Besides, the drums are much stronger know. The rope must be turned on the drum equally. There is about 150 metres (!) of chord in
the superstructure. The connections of the four winches are on the right side of the turntable. In the superstructure there are several
leads to the motors. All leads are made in the right size. However, it is not possible to disconnect the superstructure from the truck
chassis. The colossus, with its weight of 14 kilogrammes, has to be taken from the attic in one part, over small stairs ....
As I already said the operator's cab is movable sideward with the help of a 4.5 volt motor with a reduction unit. Besides that the cab is
inclinable to the rear. Therefore I have used two small pneumatic cylinders. The disadvantage of the small cylinders is that they
are not as strong as the normal pneumatic cylinders.
The A-bracket is largely constructed of Technic bricks with two layers of plates above and underneath it. A torsion resisted bar is
assembled halfway. The A-bracket takes care off luffing the main boom or the superlift. I was very surprised that the A-bracket did not
bend while the boom came off the ground.
The total construction time of the superstruction was about 75 hours. Certain components, like the winches, where modificated in a
later phase. In total I needed 165 to 170 hours to build the whole truck chassis and superstructure. I put the deco's on it later.
The logo's on both doors I made on the computer. The lettering is made by hand from stickers from a Kibri construction set. I
copied those larger on a piece of paper and with the help of a photo scanner I have printed them on transparant sheets.
Finally I put them on the model with photo glu.
The boom sections
This is not an easy job to manage and certainly not for such a huge crane. My aim was to build the crane as high as possible. I
ordered a lot of Technic beams and couple pins for this crane. I had an idea for the construction already; the boom had to be a thicker
than the earlier version of this crane. The boom constructions where not very stable and they would not be equal to such high
weights. After several calculations I have counted that the maximum boom height would be about 3.5 metres. The boom would
consist of a main boom of almost two metres with a fly jib above it.
SD-configuration: 2.25 metres height
First I have built a normal boom of 2.25 metres long and a superlift with a length of 1.8 metres. This was not that difficult and when I had
finished the construction, I took the crane into the backyard to do a testing program. Testing a model crane costs me a lot of time,
because I have to carry
all components outside. Besides that the crane must be build up. Before the boom is lifted, the indicator of the clock is two hours further.
In this configuration the main boom can be luff with two Technic motors of 12 volt. First the A-bracket lifts the superlift, after which
the main boom follows. Finally the lifting hook is hung up in the main boom. The crane works perfect and I have tested it.
Slewing, main boom up and down, lifting, everything was possible. It was in the middle of August and I would exhibit the crane for the
first time at an expo. I have exhibited the crane on this event as described above. Everything worked well untill the end of the
afternoon. The crane has crashed!! The ravage was enormous, but only a few elements where damaged. LEGO really is durable!!
Afterwards I was lucky, because the crane was not swinged a quarter. In that case I really had a big problem. The cause: because
the superstructure was slewed several times a Technic pin felt out of a Technic beam. The great advantage: everything was
cleared very quickly.
SW-configuration: 3.6 metres height
About one and a half month later I would take part with another expo. I would extend the crane further and finish the construction of
it (logo's and company names where still not put on the model). Before this event would took place, I had started to experiment with
a 3.6 metres high boom. The superlift was rebuilt to a fly jib. Mid september that was realized and I have taken all components to the
back yard for the second time. This time it has cost me much more time to build up the crane. I had never built an adjustable jib
before and it sure was exiting if every would hold the weight. I really was amazed. After a few hours the crane was operational!
Although, there was one problem: because of all efforts I have forgotten to hang the lifting hook in the crane. Before the wind would
come up I quickly shot a few pictures of it, because maybe this would be the maximum to manage. But afterwards it seems to be risky
to put the crane in this configuration in the middle of a crowd during an event. If something would go wrong, the boom maybe would
crash in the middle of the audience with all consequences you could think off. I have decided to construct the superlift once and
extended the main boom with 50 cm. The result was a 2.75 metres high crane and it also can work.
The maximum: 4,2 metres
But: you always want more. I had a target and I wanted to reach that: a crane higher than 4 metres! For some nice pictures and a
video shoot I have decided to fulfil this target. Once again I have bought some new Technic sets and constructed the fly jib for the
second time. Because I did not had enough black Technic bricks, I have made some boom sections in white and red. You can also
see that on real cranes.
Finally the crane would reach a height of 4.2 metres!! Therefore I had to wait for a suitable day to test everything outdoors. It had to be
outdoors because there you could make better pictures. A few months earlier I went to a pilot to test the 2.75 metres high crane, but I
was not satisfied with the result of the pictures. On a Saterday in November it really was calm and even the sun was shinning. A
perfect day to test a huge model! I have started with it early in the morning. Because you can't do everything by yourself, my father
has helped me building the model up. Everything was perfect: the crane boom has reached the top. During shooting some pictures it
almost went wrong: a slightly wind came up and the boom had started to bangle. An enormous power was on all guy cables. When the
pictures where made, we had broke off everything. The pictures tells you enough.
How is such a crane set up?
It has been quite a while before a crane could start its lifting operation. Before a crane actual could start a lifting operation, they
calculate the most suitable position to place the machine and how many counter
weights are needed and the necessary beam length. Build up a crane costs a lot of time, what also counts for the LEGO model.
With a normal main boom I need about one hour to build it up. In case of a 4.2 metres boom length it takes me 2 to 2.5 hours.
The machine has arrived on its destination. The crane is stripped and has to be build up. This type has the outriggers on the
superstructure already. All other components, like beam parts and counter weights, are transported by trucks. This counts for all
huge cranes like this one. The outriggers have been swinged out and extended. The pad jacks have dropped and the pad jack
boards have been fitted. Now the wheels of the truck chassis are coming of the ground. Now, a too such an extant weight pushes
on the machine, that the axles could not hold it. The pad jacks and outriggers are strong enough to haul the weight.
Now the A-bracket is placed in position. In this case the superstructure has swinged a quarter before the boom can be fitted. This
depends of the situation. Namely, it is also possible to fit the boom at the back side of the truckchassis.
The counter weights and beam parts are next. In real other cranes are needed to assist. My crane is equipped with '160 tonnes'
counter weight. It is not necessary to support the upperstructure at the back; the crane is in balance, even with a 4.2 metres boom
Finally the boom is tipping up. The quy ropes which connect the A-bracket to the upperstructure provides that the boom comes up.
Within a few minutes two 12 volt motores provides that the boom will be in the lifting position. Off course, you may not forget the lifting
Provisionally the last mobile crane
December 1998 I exhibited the crane for the last time at an expo, this time with a 2.25 metres high main boom and a superlift. Begin
1999 I demolished the crane. At this moment I haven't got further ideas to build another mobile crane. Many people ask me when I
will start building a new one, but I have to disappoint them. Since 1999 I have only build trucks and the machines which they transport.
And a new mobile crane? Maybe in the future. That could be years from know ....
Length truck chassis:
SD: 2.25 m; SW: 3.6 m; SDW: 4.2 m|
truck chassis and superstructure: 14 kg; SDW-configuration: about 30 kg|
April - December 1998|