[MOC] Lego Liebherr LTM11200

[Jeroen Ottens]

Hi,

I would like to present to you my latest MOC. It is a scale model of the 9 axle Liebherr LTM11200 telescopic crane. It is fully remotely controlled using all 8 channels of the Lego RC system to control 20 (!) functions.

The truck contains 7 functions with 4 motors (1 XL, 3 M) and 2 IR units:

1) Drive (and engage the 8 cilinder fake engine)

2) Steer

3) Switch between crab steering & normal steering (with ackerman geometry)

4) Rotate outriggers outwards

5) Extend outriggers

6) Lower outriggers

7) Switch between 1,2,3 and 4,5,6 (just like 8043 switching)

The superstructure contains 13 functions with 4 motors (1 XL, 3 M) and 2 IR units:

1) Spread guying arms on boom

2) Raise boom

3) Raise contraweight

4) Extend boom (4 sections)

5) Rotate superstructure

6) Raise guying arms on boom

7) Rotate operator cab back to front

8) Raise operator cab

9) Tilt operator cab

10) Cable drum 1

11) Cable drum 2

12) Rotate and extend optional legs on boom

13) Switch between 1,2,3 and 4,5,6 and 7,8,9 and 10,11,12 (using a nifty mechanism to engage only 3 functions at a time, thus enabling 4x3=12 functions with only 3 motors)

The boom is detachable by pulling out 4 axles. In theory it can than stand on its own legs (function 12) and the truck can drive under it.

The superstructure is also detachable by pulling out 4 axles.

Aproximate piece count so far is ~6000 pieces.

Here is an image of the gearbox of the superstructure:

And here is an image of the underside:

The green lines indicate where the gearracks are located. Each axle has a 13L gear rack at the front side and a second 7L gear rack at variable distances at the backside. One long axle with multiple 12T gears on it can be moved 2 studs. This way either the front racks are engaged (crab steering) or the back racks are engaged (normal steering). A mechanical lock is used to ensure that the switching movement is only possible when the axles are at 0 degree turning.

However, the sad part is that a some functions do not work . Lifiting the boom is impossible due to the weight. Rotation is impossible with the Lego turntable that I used.

Functions that do not work, but that can be fixed:

all outrigger functions (I need to reduce the play in the gear train at some critical points, but that seems to be doable).

the switching mechanism in the truck (it works, but it is not foolproof)

the steering needs to be geared down

Giving the fact that I'm pretty sure that I can't solve the boom raise issue I wonder whether or not it makes sense to go through another design iteration to solve the other issues or that I should leave it at this. What is your opinion?

Jeroen

[efferman]

holy moly what a huge thing. for lifting the boom, maybe you can use a winch system like which is used in girder mast cranes.

it is not the correct method, but i think it is the only way to lift this boom.

[trekman]

Hey Jeroen, I know what it feels like to get so far and discover that some functions do not work as expected. Then the problem is that if you try to rework, then you can actually compromise on something else. It's not my crane, so I would be looking at it differently, but I do know that you have fitted in some amazing functions. For example the dual mode steering on the shifting axle, as well as the 4x3 function gearbox, as well as other features.

My opinion would be to present the MOC despite it's failings, and then go away and rebuild the features into a crane with a smaller functioning boom.

Well done on what you have done anyway. (You know we don't always get MOCs right first time) & have a happy New Year

[Hrafn]

Wow! The whole thing is very impressive. I'm also more than a little envious of the number of parts you have.

The way you switch between Ackerman and crab steering is very clever - I may have to steal that!

How much is the XL geared down to lift the boom? How heavy is the boom, and how long? Is there any way you could gear it down more without losing too much power to friction?

[Jeroen Ottens]

Wow! The whole thing is very impressive. I'm also more than a little envious of the number of parts you have.

The way you switch between Ackerman and crab steering is very clever - I may have to steal that!

How much is the XL geared down to lift the boom? How heavy is the boom, and how long? Is there any way you could gear it down more without losing too much power to friction?

Feel free to steal , that's what this forum is for. It is a tricky system though. I use two gearracks in the front and the back of the model to push the axle either way. However the sum of the axle lengths is not equal to the length of the model (each axle is o so slightly shorter than an integer number of studs and when you have so many connected the total length is significantly shorter, in this case ~0.5 stud). If you're interested I can make a picture of just the steering mechanism.

The boom is a few kg's and 70 cm long.

It is geared down with a worm gear * 24T and then it uses a wormgear to drive the gear racks in the pistons directly. However the power of the motor is not the problem. The amount of torque in the piston is so great that the elements are pulled apart. I can reinforce that part of the piston even further, but it will compromise the looks.

[JGW3000]

We face similar issues at work all the time - my arguement is always to get the device working and do your proof of concept, and along the way you can figure out how to make it more efficient, less expensive, more like the intended outcome - since you have come this far with your fantastic MOC, I'd keep going and try to lift the boom regardless of what is required. If the end result is not acceptable, you will at least have learned the limits practical building with Technic.

[Pyropetepete]

Would like to see video of what works so far. Amazing

[Rishab N]

Wow that is amazing!

[timslegos]

I would love to see more photos as well! Simply insane how many functions you have managed to build in!

tim

[jantjeuh]

Wow, that looks amazing. Perhaps make lifting the boom hand-operated. You have plenty of other functions that are remotely controlled.

Edited December 27, 2013 by jantjeuh

[Zerobricks]

Its a good try, even if not all work, its still a good learning model!

[nychase]

I highly recommend the Firgelli Actuators. They have two different throws (50 and 100cm) and the strength is fantastic. You might need to double or even triple them for this boom but I think it will work. Plus, don't forget that the motor is built into the unit so you wont need to find an alternate housing for motors or worry about axle torque. I used just one of these to life a heavy boom and it can lift it at FULL extension from level. Its a 45 stud long boom with a 40 stud inner boom, and its completely studded so there are no weight savings.

http://store.firgelli.com/category_s/1822.htm

I can try to answer any questions you might have if you need.

[Lakop]

Brilliant work. I like what you've done and I like that you've presented it despite the boom not functioning etc, it shows faith that no one is going to be negative about it. This is a very positive forum and website. Could you look to raise the boom in stages or deploy pnuematics on mass. I'm sure between us all we can come up with something. Just had a thought, maybe it needs the help of a smaller crane to build it. Could it be part of a crane team?

H

[Johnny P]

how about combining multiple pneumatique cilinders?

lets say 8 minimum or so?

i wouldn't give up to fast.

just imaging finishing this fine piece of engineering.

what a beauty it would be.

Edited December 27, 2013 by Johnny P

[Paul B Technic]

This is HUGE. Thanks for sharing :)

[Jeroen Ottens]

how about combining multiple pneumatique cilinders?

lets say 8 minimum or so?

i wouldn't give up to fast.

just imaging finishing this fine piece of engineering.

what a beauty it would be.

Thanks for the encouragement , it is indeed a great goal to have it all in working order .

Pneumatics will not do the trick I'm afraid. I need a stroke of 14 studs, that requires 4 cilinders in series. I see no way to combine that into the volume that I have available (4x4x27 studs)

When I assist the boom with my hand I can make it raise. Lowering it can do all by itself (although it takes >5 minutes).

I highly recommend the Firgelli Actuators. They have two different throws (50 and 100cm) and the strength is fantastic. You might need to double or even triple them for this boom but I think it will work. Plus, don't forget that the motor is built into the unit so you wont need to find an alternate housing for motors or worry about axle torque. I used just one of these to life a heavy boom and it can lift it at FULL extension from level. Its a 45 stud long boom with a 40 stud inner boom, and its completely studded so there are no weight savings.

http://store.firgell...gory_s/1822.htm

I can try to answer any questions you might have if you need.

I hadn't thought of these ones. Even though I have seen them come by in this forum. I need a stroke of 14*8=112 mm. That is close to the max stroke they offer. It would be a small compromise. Then again I would like to first try to solve the challenge with all Lego parts. So I'll keep this in mind. Thanks for the link.

Brilliant work. I like what you've done and I like that you've presented it despite the boom not functioning etc, it shows faith that no one is going to be negative about it. This is a very positive forum and website. Could you look to raise the boom in stages or deploy pnuematics on mass. I'm sure between us all we can come up with something. Just had a thought, maybe it needs the help of a smaller crane to build it. Could it be part of a crane team?

H

Thanks for the kind words. This is indeed a very positive minded forum.

I like the smaller crane idea, however it can't be a too small crane: the top of the first section is ~80cm above the ground when fully raised and it would still need to lift a considerable mass.

Edited December 27, 2013 by Jeroen Ottens

[Pyropetepete]

I highly recommend the Firgelli Actuators. They have two different throws (50 and 100cm) and the strength is fantastic. You might need to double or even triple them for this boom but I think it will work. Plus, don't forget that the motor is built into the unit so you wont need to find an alternate housing for motors or worry about axle torque. I used just one of these to life a heavy boom and it can lift it at FULL extension from level. Its a 45 stud long boom with a 40 stud inner boom, and its completely studded so there are no weight savings.

http://store.firgelli.com/category_s/1822.htm

I can try to answer any questions you might have if you need.

Thanks for that link. I'm going too treat my self to some of these for up and coming projects. 4 of each and matching cables should be me covered.

[olaf9198]

That is awesome! Can you make more pics? And it looks like the operator cab is hanging a bit lose, is that right? Anyway, great MOC !

[Jeroen Ottens]

That is awesome! Can you make more pics? And it looks like the operator cab is hanging a bit lose, is that right? Anyway, great MOC !

Thanks. The operator cab is lowered halfway in picture. It can lower to the ground, or raised to above the superstructure level. I'll try to make a video of that function tomorrow to show what I mean.

[TinkerBrick]

This is really impressive. Given the sizes of this moc, why don't you try a Self Build LA. I found this on TechnicBricks:

http://www.technicbricks.com/2008/09/tbs-techtips-16-la-discrete-design.html

[paulincanada]

Well for what it's worth, I say continue! That looks awesome.

[Tamas Juhasz]

Impressive project, I like the function switching mechanism.

I wonder that nobody thought about string operated actuators:

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=534220

Extremely strong, small, can be built in different lengths. Except for the string it's 100% Lego.

[zux]

Wow, this is amazingly huge MOC. That steering mechanism sounds smart. I understand that not all of the functions work as expected, but I wish to see a video of the ones that are OK.

[Technic Builder]

Looks really outstanding. Great simple solution to the two steering modes. I'm kicking myself for not thinking of something like that. Any more pictures or a simple video of the control setup would be awesome. Love the studless technic look.

[Jeroen Ottens]

Hi,

Happy New Year! After all the encouragment I received last week I have decided to continue my design. And not without succes :

- I have been able to strengthen and gear down the geartrain for lifting the boom: it now can lift itself (but only without the extendable sections).

- I built a rollerbearing for the superstructure and redesigned that geartrain: rotation works very smoothly now

- I strenghtened and geared down the geartrains in the truck: driving, steering is going well

- I strenghtened the geartrains for the outriggers: extending the legs is OK, spreading the outriggers works better, but is still not good enough, extending the outriggers is impossible . I made a thinking error in the way the axles should turn. The left outriggers want to extend, while the right outriggers want to contract at the same time. More redesigns needed here...

I shot some videos, but the quality is really awful , so I haven't uploaded them. Sorry. I do have some pictures of the gear trains though:

These are all the functions in the superstructure:

They are colour coded (blue, yellow, red, green) for the 4 groups of each 3 functions. I have now tested 10 of the 12 functions (extending boom & extending boom legs excluded) and they are working fine. I changed the order around a bit. The cable drums now are in the same group as extending the boom. This way you can extend the boom at the same time as rolling out the cables to keep the hook at the same height (assuming gear-ratios do match).

And this is the geartrain of the truck, with only the steering & driving parts:

The pink stuff is used for the switching between the steering modes, the dark purple is the steering. The medium purple is for driving the two wheels below the turntable. For the clever ones: there is a special relationship between the position of the grey axlejoiners and the 12T gears for the steering.

So thanks again for the support and I'll keep you updated on any progress (slow probably, because holiday is over for me).

Jeroen