Highly extendable cylinder/actautor for Lego mobile cranes

[Tamas Juhasz]

Hi!

About 3 month ago I was thinking about a long "pneumatic" cylinder, or actuator, which can raise heavy booms, and made only of Lego parts except one or two. I was searching something to that, when I saw this pillar: http://www.bricklink.com/catalogItem.asp?P=6168c01

I have a brown one, but it's very good for craeting an actuator with long extension:

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=510750

Only one custom part was added, a 0,1 mm fishing line, which is enough strong to lift the wieghts in the video below. It's a very simple and reliable mechanism, an axle screws up the fishing line(I think there isn't a lot of difference between custom strings and this), and that pulls out the 12 or 16 L axle from the cylinder:

The fishing line can be placed in the up of the cylinder(this is better, because in this case it helps to raise) or sideways.

The mechanism in the pictures is only for showing it's working, the cylinder can be placed in many ways.

I needed something to my future mobile crane projects, and I really don't wanted to build a very big actuator from regular technic parts. Or something with custom metal parts. The "Support 2x2x11 solid pillar" is also available in yellow, so it fits well to mobile cranes.

To increase the capacity of lifting, two, three, or four of them also can be placed next to each other:

The maximum extnension(is this the good term?) is about 13 stud when you use a 16L axle:

http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5583601

http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5583600

Video:

[jorgeopesi]

Great, great, great idea, for a big dumper or a crane is perfect where the cylinder only has to lift, not so good for an excavator but we will see, nice idea again.

[Alasdair Ryan]

Love it.

Going to bricklink now to order some of those yellow beams......

[timslegos]

Nice design, although I am worried that the line will cut into the brown piece over time.

tim

[Tamas Juhasz]

Thanks guys. Yes, the line cuts a bit the pillar(lifts more kilogramms), but after it cutted, than cuts no more, create a small "corridor" to move. If you use it in one side from the four, it's a minimal damage, but I would be more happy if it won't cut. I didn't find a better solution, you need a very strong line to get this power, and it's easy to motorize. My pillars are only used for this actuator.

Edited August 24, 2012 by Mbmc

[Alasdair Ryan]

Could you attach some sort of pulley on the end to stop it digging in?

[Tamas Juhasz]

I think that's not impossible, I will think about it. Some small parts would be good with relatively large surface, and the line would hold it in place, because you can't build more parts to the end of the pillar. But if we won't find a solution to that, and it cuts, then do it. That's a very small damage.

Edited August 24, 2012 by Mbmc

[Alasdair Ryan]

What about one of these?

[Tamas Juhasz]

That part has also a 90 degree edge where the line connects to it, but two of them, so it can decrease the effect, but the cylinder wouldn't look so good with that.

Edited August 24, 2012 by Mbmc

[Alasdair Ryan]

That part has also a 90 degree edge where the line connects to it.

Yep you could fit one of these with just the rim on it.

That might not work.

Could you just use string instead as that is softer than fishing wire?

Edited August 24, 2012 by Alasdair Ryan

[Tamas Juhasz]

Yep you could fit one of these with just the rim on it.

Oh.. yes. Great idea, and this can be is the solution for cutting, but the cylinder would be bigger, and many times you don't have so much space between the cylinder and the boom to place there also these parts.

Edited August 25, 2012 by Mbmc

[skylinedan]

I,m working on something that will address this problem, it wont be LEGO though. I have to go to the hobby store near me and see if they have the stuff I need to build it, I will say it is very similar to what you got. More or less to tubes one fits in side the other with some clearance for the string on either side, at the top will be two pulleys. No down force, strictly for lifting like your set up. I want to build a truck crane,and I,m not happy with the current ways to lift the boom.

Dan

[Tamas Juhasz]

Sounds interesting. Post picrures when you made that actuator. But I will use this, I don't want metal parts in a moc. Two of them is enough to a 94.3 wheeled 4 axle crane.

Yep you could fit one of these with just the rim on it.

That might not work.

Could you just use string instead as that is softer than fishing wire?

I tried it out, and it doesn't work, the original placing of the line is the best until now. The roller doesn't help, the line always touches an edge.

String wouldn't be better than fishing line. It's much more weaker and would cause more friction between the cylinder and the axle. What's the problem with fishing line? Works well with that as can be seen in the video. Ok, not Lego, but if you use a non Lego string, that's also not Lego.

Edited August 25, 2012 by Mbmc

[skylinedan]

Sometimes you have to bend the rules to get the outcome you want, people are using third party tires on their crawlers. SO what if a guy comes up with a working long ram that will work for cranes and anything that needs lifting, but no down force. LEGO comes up "short" when it comes to LA,s, LOL.

Dan

[skylinedan]

Just finished three extendable axles, I figure out how to post pictures on here you guys can tell me what you think. There all LEGO except for the main tube on the outside, I used 3/8" PEX tubing. The pull back piece that the axle goes in fits really tight inside it to the point you dont need to glue it. I,m gonna work on a phumatic cylinder that will give me the lenth I need to build a proper crane, and something like your set up. I want to figure out a way around the friction problem where the string comes out of the tube.

Dan

Just finished three extendable axles, I figure out how to post pictures on here you guys can tell me what you think. There all LEGO except for the main tube on the outside, I used 3/8" PEX tubing. The pull back piece that the axle goes in fits really tight inside it to the point you dont need to glue it. I,m gonna work on a phumatic cylinder that will give me the lenth I need to build a proper crane, and something like your set up. I want to figure out a way around the friction problem where the string comes out of the tube.

Dan

[Tamas Juhasz]

Sounds good, I am curious about it. But why is there problem with friction in my actuator? Think about it: with that friction the working of my actuator needs only more power from the motor, but that doesn't matter, because the extension is slow(a very fast lifting won't be good). A medium motor with 5:1 reduction moves it very well and srongly. The limit is the fishing line's tensile strength.

Sometimes you have to bend the rules to get the outcome you want, people are using third party tires on their crawlers.

Yes, custom parts are used, and they makes the moc a Lego-custom hybrid, depending of the used cutom parts in %, for example if you have a moc with 100 piece and from those two isn't Lego, then it's 98% Lego. With custom tires performs a crawler very good, but but this is the minimum, with a custom tire it's not hard to achive incredible abilities(imho ).

Edited August 26, 2012 by Mbmc

[jorgeopesi]

It is easy for me, if you need non Lego parts then it is not a Lego MOC for me, what is the limit?, wheels, linear actuators, motors. It will be a great MOC but not a great Lego MOC, call me purist.

[Alasdair Ryan]

I only use non-lego string,band's and pneumatic cable as these are expensive parts to get when dealing with the amounts I need.

[skylinedan]

Not saying that everything I build will have non LEGO parts, just that in some cases you need something that LEGO doesnt have. I can relate on being a purist, but if we never think outside the box somethings will never be built.

[jorgeopesi]

I only use non-lego string,band's and pneumatic cable as these are expensive parts to get when dealing with the amounts I need.

That things can be use in my opinion without problem but I say again in my opinion, everyone can do whatever he wants of course , I am a purist for my MOCs.

[Tamas Juhasz]

Yes, I also think so. A Lego moc is made with Lego, or 99%+(but it depends also on the weight of the non Lego part) Lego.

Not saying that everything I build will have non LEGO parts, just that in some cases you need something that LEGO doesnt have. I can relate on being a purist, but if we never think outside the box somethings will never be built.

Yes, there are many ideas which are impossible to make with the current Lego parts(mostly small structures). If something is not possible to build, then I think we shouldn't build it instead of making custom pieces for that. Lego technic has many limits. I also used non Lego motor and metal wires long ago, and those weren't so much Lego mocs in my eyes. But if somebody(like you) made a custom (even metal) part to mocs, which fits well to the Lego system, that's not bad. It's a complicated theme, depends on the mocer to use custom parts. I use only custom strings(damils) and rubber bands. We can also think outside the box, if we see the possibility of using a non technic part as technic part. Or parts from assembled units, like this: http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5494302

I understand you, sometimes I have the feeling it would be very good if I had a part which doesn't exists. For example a 24 tooth clutch gear, like the 16t. That's what I need since long ago.

Edited August 26, 2012 by Mbmc

[Tamas Juhasz]

I found a solution for cutting in the pillar:

http://www.brickshelf.com/gallery/mbmc137/Ideas-Technologies/LongCylinder/020.jpg

http://www.brickshelf.com/gallery/mbmc137/Ideas-Technologies/LongCylinder/021.jpg

Doesn't solves the problem completely, but decreases much the effect. But now it's uglier.

[jorgeopesi]

Looks like I have to buy some pilars, they will be useful

[Burf2000]

I had come up with a similar idea for someone in our club, nice to see it working and it is prettier than the solution I suggested!