PistenBully 600

[MOC] Liebherr 250 EC-B Towercrane 1:18

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Hello everyone,

My current project is the construction of a Liebherr 250 EC-B towercrane in 1:18 scale. The model is fully functional. The hoist winch is powered by one XL-Motor, the trolley winch uses one M-Motor and the slewing ring is powered by two L-Motors. All motors are controlled by an S-Brick. I have started building this model 4 months ago.

Here the crane is assembled with 110 cm tower and 180 cm jib:

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The maximum height under hook is about 2 meters; the maximum jib length is 230 cm. The total length of the model with 230 cm jib is 330 cm.

Here the crane is assembled with 150 cm tower and 230 cm jib:

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The crane can be disassembled into the same number of small parts as the real crane. These parts have roughly the scale measurements.

 

Thanks to efferman´s turntable support ring the slewing ring is quite stable and rotates well (in the first video above the support ring was not attached yet, that is why the crane swings so much when it lifts or drops the load). The maximum capacity of the crane is approximately 400 grams in 2 fall-operation. But there is a second trolley and hook which allow an automatic change between 2 und 4 fall operation. The mechanism is the same as used for the real Liebherr fast erecting cranes und smaller EC-Bs.

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Edited by PistenBully 600

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I spent the last two months in creating a climbing unit for this crane. Real tower cranes use climbing units to climb up along growing buildings during construction.

The climbing unit lifts the complete upper part of the crane, including the crane head and counter jib. A hydraulic cylinder mounted at the climbing cage braces itself on a “K” shaped strut of the tower and presses the upper part of the crane upwards. This happens 5 times until there is enough space beneath the slewing ring to insert the next tower section.

Here is an animation that shows the system developed by Liebherr:

 

 

The climbing unit was the most difficult feature of this model. At first, with the crane in its smallest configuration with 150 cm jib, it has to lift a weight of 4.2 kilograms. The finished climbing unit has a weight of 1.8 Kilograms, so the total load that has to be lifted (including one tower section in front of the climbing unit) is around 6.5 kilograms. This load is lifted by two linear actuators, extended by strings with a tear strength of 35 kilograms. Any other string I tested has torn. The two cylinders are powered by one XL-Motor using a worm gear with 1:24 reduction. But anyway the motor has to struggle with the weight.

Fortunately I found out the right dimensions of the climbing frame so that it guides the tower very well without too much friction or backlash, which is very important for the climbing process. This is because the climbing unit has to absorb all kinds of imbalance of the upper crane, which could not be adjusted by the counterweight or the position of the trolley and hook. So the climbing cage has to be very stable, too. Especially when the climbing process itself is done and the next tower section can be inserted. At this time, the climbing cage touches the tower at a length of only 15 cm. All upcoming forces have to be absorbed by this small part of the cage.

But this is enough of writing – after all there was the final load capacity test with a load of 4.8 kilograms (6.7 kilograms including the climbing unit). And what shall I say? It worked! Here is a picture of the climbing cage lifting this weight:

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After adding some details such as walkways and a small trolley powered by 2 micro motors for inserting the tower sections, the climbing unit was finished:

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The lifting unit:

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Here is a video of the climbing process:

 

And a video of the crane climbing back down. In real life this happens when the construction of skyscrapers is completed and the crane can be disassembled:

 

At the moment I am improving the model and I am reducing some weight in the upper structure.

The jib lost 200 grams at a length of 200 cm:

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All in all this is a very cool project for me and I like the result. I hope you like it, too - feel free to comment.

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Great model and I am just in awe, especially regarding the short timeframe it took to this point! :) 

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Love it, especially how all the studded parts make it look so imposing.

Do you have a link to the string you used?

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A big waow. And congratulations.

Probably one on the best model I've seen these days. I'm very surprised by the stability during movement, even with a load. Very great work.

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