Although it's a Work In Progress for over 3 years already, it will be finished some day, so lets make a topic about it.

I've been working on a unimog wheel based four axle mobile telescopic crane, the Liebherr LTM1100. The undercarriage is already standing around in semi finished condition for quite some while, waiting till I got inspired again. And while I was tearing down the 42009 I got my inspiration back! Since then I started building the superstructure and crane boom. Because of the scale I was able to make a four stage telescopic boom without making one or more of the sections look out of proportion. This posed a nice challenge, and I think I tackled it by now. At full extension, the boom now reaches to about 2,5 meters. In the pictures, the top part reaches past the ceiling actually.

Boom by Thomas Joling, on Flickr

Boom by Thomas Joling, on Flickr

And a video I made this morning, testing if the mechanics for lifting the actual boom were up to the task:

As you can hear, they are not, but we'll fix that :D

For other pictures, head to the flickr album

If you have any questions, put them below :)

Ok, I will follow this very closely.

I am building one Liebherr Crane in the very similar scale (1:13) for the last three years, and I know the challenges. I am glad to have one more big crane project to observe.

1. awesome!

2. I am so intrigued by all the mechanisms in the crane's carrier, but at the same time, it looks organized.

3. Why no suspension at the end?

4. Steering is greatly executed. I am aiming to the four steering modes, will see how it will work at the end.

5. Boom is a little bit too wide. LTM 1100 is 2.5 meters wide, and in this scale, boom should be around 6 studs wide, your is 9. But having three telescopic sections is cool :)

6. Boom cylinders looks and works great. I have developed similar using strings, cant wait to compare them. You just need to reduce the XL motor 3 times.

7. Does telescoping works ok?

8. Do you think gearbox will survive the weight?

The sheer size of the boom is very impressive. With so much weight I wonder if the chassis will be able to hold it all up! Also the steering system looks a little weak for the weight. Regardless I look forward to seeing the finished product.

tim

Ok, I will follow this very closely.

I am building one Liebherr Crane in the very similar scale (1:13) for the last three years, and I know the challenges. I am glad to have one more big crane project to observe.

1. awesome!

2. I am so intrigued by all the mechanisms in the crane's carrier, but at the same time, it looks organized.

3. Why no suspension at the end?

4. Steering is greatly executed. I am aiming to the four steering modes, will see how it will work at the end.

5. Boom is a little bit too wide. LTM 1100 is 2.5 meters wide, and in this scale, boom should be around 6 studs wide, your is 9. But having three telescopic sections is cool :)

6. Boom cylinders looks and works great. I have developed similar using strings, cant wait to compare them. You just need to reduce the XL motor 3 times.

7. Does telescoping works ok?

8. Do you think gearbox will survive the weight?

I'm afraid the pictures of the undercarrier aren't very representitive for the end result with regard to the technical solutions. I've discarded the idea of the gearbox as it doesn't much to the model, because only the third axle is going to be driven, so I'll apply only the minimum required torque to the wheels in order to keep all the parts intact. More torque provided by a gearbox would only break parts, which isn't my intention :P Also the clip showing the steering system is actually out of date; the system had to much play, wasn't strong enough and had too limited possibilities. It was actually based of an adder-subtractor system, but instead of a driven left and right track, the front two and rear two axles were steered. I am now aiming for the four different steering modes too. So a whole new carrier is being designed, at least technically. Still no suspension though, because I think the added play in the axles will harm the drivability when it's finished, especially because of the huge weight in the end. Also, the chassis will now be stiffer and I have a lot more space to accomodate the steering system. And again, it wouldn't add much IMHO since trial-like activities are alredy out of the question ;)

You're right about the width of the boom, but I think only people familiar with the matter will notice that. Besides it's a technic model, so added technicallity of the four stage boom is prior to the aestetics :P The telescoping is really smooth, except for the last stage. I have yet to motorise it though. Just as the boom raising cilinder it is going to be rope driven. The rope inside the cilinder is running up and down 2 times, giving a mechanical advantage of 4 so it is very strong indeed. The skipping in the transmission of the winch is probably caused by the actual warp of the winchaxle, because the rope more or less pulls the winchdrum away from the gears driving it. The winchdrum is now geared 12:36 and 12:20, but I'll probably change that to 12:36 and 12:36, accomodating the added weight of the telescopic stages which were left out in the video.

The progress of the last weeks. The superstructure received a new brick built frame, which is more rigid and less bulky than the studless frame it had. The turntable has also been changed, the actual turntable is turned upside-down so the superstructure can not detach from the undercarriage. Now tiles are used as bearings, so I hope this won't have to much friction, otherwise I have to put rollers under the superstructure. Up until now everything is smooth sailing though.

Next up, getting the undercarriage to steer as it is supposed to do.

Edited April 17, 20159 yr by TJoling

Looking real good :)

Can't wait to see the final product !

Looks massive, how much does the boom weight?

Thanks kisper!

The weight of the boom all in all is about 700 grams I guess. It's quite a heavy piece of kit.

Thanks kisper!

The weight of the boom all in all is about 700 grams I guess. It's quite a heavy piece of kit.

Wow, have you considered lubricating the turntables? Blakbird told me that improves traverse time considerably and reduces strain on the motor, increasing motor lifespan and making the battery last longer on one charge.

Hey, I'm following this as well. I just started my own project of a large-scale mobile crane, with 12 unimog wheels.

Wow, have you considered lubricating the turntables? Blakbird told me that improves traverse time considerably and reduces strain on the motor, increasing motor lifespan and making the battery last longer on one charge.

I might do that if the friction turns out to be too much, but i'm not afraid of that since the turntable isn't a loadbearing piece between the undercarriage and superstructure

Hey, I'm following this as well. I just started my own project of a large-scale mobile crane, with 12 unimog wheels.

Sounds interesting! I'm curious how you are getting allong

Sounds interesting! I'm curious how you are getting allong

It's very early. I'll create a topic when I have something to show. For the moment, I have the scale roughly figured out and started working on the axles (suepension, transmission, steering...).

Time for another update. Last weekend I brought the beast to a local AFOL meeting where this photo was taken by Barman:

The cab is rebuilt in the meantime, so it starts to look like the real thing now. Also, the winch systems in the superstructure have been fitted and re-fitted to accomodate the immense forces exerted on the parts. At this moment, the winch for extending the boom is functional. It is powered by a L-motor and a 1:24 geardown. Only the last section has to be extended manually, but it will probably be rebuild so it will be extended automatically with the other parts.

The winch for raising the boom has been overhauled completely. At first, the geardown for the winch was only on the outside of the frame, which resulted in the twisting of a 5 studs long section of an 16L axle The winch is now first geared down 1:5 before the axle is led to the outside of the frame where further geardown will be built. Hopefully this will make the winch a little more reliable. Small problem is now fitting the XL-motor to the outside of the frame, since there's only 5,5 studs left to put it, otherwise it would stick out to the side. After that's done, and I found a sollution to drive the hoist winch without any gears or axles sticking out of the body, it's down to the undercarriage to try to make the steering system work, and to see if the beast will actually move by itself. Hopefully we've conquered the biggest hurdles by then. But that's a long way away for now

3 months later...

The raising of the boom is functional! Complete with all 3 three of the extensions it can now be raised by a single XL-motor:

The noise is caused by friction of the rope, not gear skipping.

Next step: motorize the hoist winch.

Quite impressive that a single XL motor can raise the boom. To me it looks much more massive than 700 grams. In this thread you mentioned that you "guess" it weighs that much. Is that just an educated guess or did you actually weigh it? Also, it might help things and decrease the stress on the ropes while lifting the boom to add lubricant to the tops of the light bluish gray tiles that rest underneath the boom extension. Really great job overall..... it takes a lot of time, dedication, money and patience and diligence to stick with a project for so long.....

Well, it's an educated guess, based on holding the boom with a stretched arm. I could be off by about 100 grams :P

I built a new internal frame after shooting this clip, which now connects the cylinder and winch, making the structure much stiffer, reducing friction in the winch gearbox by a great deal. The XL is now capable of raising the boom on just speed 1 of 7 of the PF batterybox! To be honest, I had lubricated the piston as well on that attempt.

It also takes a lot of parts; I've destroyed parts beyond recognition in ways I didn't suppose to be possible before destroying other parts first.

Wonderful.... Keep at it. I love large projects. I will continue to follow this one. It is really looking good.