4 section boom

[rjk1977]

hi there , i am building a fully RC Liebherr LTM , now i have a problem becouse i want to install a 4 section boom in it , but i have maneged to build it so it can come out (thats not that hard)

but i can't think of it that it would come back in.

Can anybody help me with this problem??

[jantjeuh]

Some pictures might be helpful ;-) Show us what you've built & tried so far.

[DLuders]

@ rjk1977: If you look at this Eurobricks topic, and scroll half way down that webpage, you'll see some pictures and a diagram of a 3-section boom. Perhaps you could adapt those ideas into your 4-section boom....

[Sariel]

You, sir, should be aware of Jennifer Clark's ideas:

More: http://www.jenniferclarkbass.com/lego/ideas.htm

[jantjeuh]

Looks like we have a consensus here

Interesting design, I'm thinking of adopting it for my yet-to-be-built crane.

Edited October 27, 2010 by jantjeuh

[rjk1977]

Some pictures might be helpful ;-) Show us what you've built & tried so far.

Yes i know , but i tried it in small scale and took it apart again, now i'm waiting for parts i ordered so i can build it in bigger scale ,i will trie to leave some pics as soon as possible

this is an idea what i have in mind

Edited January 19, 2012 by rjk1977

[jantjeuh]

Yes i know , but i tried it in small scale and took it apart again, now i'm waiting for parts i ordered so i can build it in bigger scale ,i will trie to leave some pics as soon as possible

While you're at it, why not go for a eight-section boom?

Would love to see the LTM 11200-9.1 as a MOC

[rjk1977]

While you're at it, why not go for a eight-section boom?

Would love to see the LTM 11200-9.1 as a MOC

wow yes i really like to do it , but then i need a ton of parts ,and then its really huge, but who knows lol , first a Liebherr LTM1100

Edited October 27, 2010 by rjk1977

[Countdown]

wow yes i really like to do it , but then i need a ton of parts ,and then its really huge, but who knows lol

Why aren't you using chain links? I found this a couple months ago, but I can't remeber from where; I was really impressed and never got to build something similar

[jantjeuh]

first a Liebherr LTM1100

Cool, Sariel is building a seven-section LTM 1200 I believe.. maybe you two can swap ideas :)

I'm interested in the six-section LTM 1250 myself, but I need more parts/spare time first.

[Sariel]

I found this a couple months ago, but I can't remeber from where

This is an idea by Erik Leppen, the Ultimate Crane Master :)

Personally, I think the main problem with multi-section booms is the friction that increases greatly with every section. I mean, you can built 4, 5 or 6-section telescopic boom, but you may not be able to actually extend it. I've experienced so much friction with long 3-section booms based on Jennifer's idea that many types of string couldn't handle the load while extending.

Having said that, I have no ambition to have more than 4 sections in a single telescopic boom. It's possible but impractical.

Edited October 27, 2010 by Sariel

[jantjeuh]

Yeah, I kind of expected that for more than 3-4 sections. However, I think I might add some more sections just for looks.. I can always give it a nudge to help it while it's extending ;-)

[rjk1977]

<br /> I've experienced so much friction with long 3-section booms based on Jennifer's idea that many types of string couldn't handle the load while extending.<br />Having said that, I have no ambition to have more than 4 sections in a single telescopic boom. It's possible but impractical./>

I'm planning to use steelcable for extending, i hope it would be strong enough.

Jennifers idea is extending AND retracting ? right?

Edited October 27, 2010 by rjk1977

[Sariel]

Right.

[Smithy]

Large cranes do not extend all sections of the boom at the same time - unlike the smaller cranes.

The larger cranes ones have one cylinder and push one section out at a time, starting with the innermost section. that section then locks in place, the cylinder retracts, and pushes out the next section and so on.

[DLuders]

On the TexBrick website, there is a 3-section telescoping boom (with a jib) that has these details:

From http://www.gaasedal.dk/eng/Mobile_Cranes/Grove_GMK4075.html :

Edited October 28, 2010 by DLuders

[rjk1977]

Large cranes do not extend all sections of the boom at the same time - unlike the smaller cranes.

The larger cranes ones have one cylinder and push one section out at a time, starting with the innermost section. that section then locks in place, the cylinder retracts, and pushes out the next section and so on.

They don't start with the innermost section, the operator can choose out of all sections whichone puched out first. I have thought of this principle but i think its impossible to make it work in a lego creation