Extreme actuator (long extension)

[Tamas Juhasz]

Hello!

I made some experiments nowadays, also this string operated actuator for heavy equipments:

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

(this last picture is from another model, just shows the working method)

The working pricniple is very simple and effective: the winch in the end of the housing (yellow) pulls out the liftarm construction (gray) with string(s). This isn't realistic, but think about TLC's actuators, they aren't also. I made it for heavy equipment, like crane booms, excavator arms, etc. For raising a big boom, pneumatic has no chance, Lego actuators also. There are two ways after that: custom actuators/custom pieces, or built actuators. I think string is "legal", it can be made also with Lego strings (but would be expensive), so it's 100% legal.

The extension is 15 stud (can be a few studs more, but that would be in the "limit zone"). With longer construction it can be even 30 studs (more would cause deflection).

I wanted to make it as small as possible, it's 3,8 studs wide, 3 tall. The length can be chosen freely (as long as you want - you just need longer liftarms, or more). The final version in my projects will have bley thin liftarms instead of these black ones, so it will be looking like a real cylinder from a distance.

There is 4 paralell strings in this actuator, and at the beginning of the housing there is a little pulley to decrease friction ( http://www.brickshelf.com/gallery/mbmc137/Ideas-Technologies/Extrem-Cylinder/003.jpg ). Strings are very good for smart techniques, this actautor doesn't requires much additional space for motorizing, just make a gearing with a motor after the winch's axle. Of course, you can change the strength of the actuator with stronger/weaker strings. The one in the pictures can create about 100 N of pushing force. This is a bit more than a 10 kg vertical lifting. The backward movement is done by the gravity, but it's not impossible to modify it to pull back the inner part (you can add another string, like 8421's boom extension works).

What do you think?

[Surly]

A rubber band in the base of it would assist gravity and still be lego legal?

Cheers

Surly

[jantjeuh]

Looks sturdy and useful, would be nice to see a video of it in operation :)

[Rockbrick]

Bravo for keeping the lego purists happy !

[Jeroen Ottens]

Nice design. I've been studying this topic as well lately. I found the use of the 3x11 panels for the outer shell very useful. That way you can even satisfy the studless purists + you get a rounded under (or top) side. It does come at the expense of a 4 wide cilinder though.

[Tamas Juhasz]

It's good to hear you like it.

A rubber band in the base of it would assist gravity and still be lego legal?

That could work, but this actuator is for heavy booms, they can easily pull back the inner part. If the moveable structure/part isn't heavy, then we can use the regular methods to move it. I'm just trying to say that I see no application where big force is needed in both ways.(ok, rubber band can't create much force, but then it's unneccessary, gravity does the same)

Looks sturdy and useful, would be nice to see a video of it in operation :)

Maybe I will make a video later, but wouldn't be so interesting, you would see a raising boom or something like that.

Nice design. I've been studying this topic as well lately. I found the use of the 3x11 panels for the outer shell very useful. That way you can even satisfy the studless purists + you get a rounded under (or top) side. It does come at the expense of a 4 wide cilinder though.

Thanks. 3x11 panels? Do you think about the new (42009 have them) ones? How could I keep the ~ 4x3 profile size with those? I think they would be much weaker also. There isn't stronger connection than plate-liftarm put together. Only advantage would be a bit more rounded shape, but black "pins ends" and holes could be seen.

Edited September 17, 2013 by Mbmc

[jantjeuh]

Maybe I will make a video later, but wouldn't be so interesting, you would see a raising boom or something like that.

A video where it lifts 10 Kg ;-)

[Junpei]

I know I've seen a crane built by a now (I think) inactive member of EB that had 16 (!) pneumatic cylinders to lift the boom. I think an actuator made with 3x11 panels with a 3x3 piston would be great for that kind of model, and the wider piston and longer stroke would make it more robust and realistic.

[Tamas Juhasz]

A video where it lifts 10 Kg ;-)

It's built in pretty deep in a moc, so maybe I should make another actuator for the video, when I have time. The problem is, I don't have 10 kg weight from small objects.

I know I've seen a crane built by a now (I think) inactive member of EB that had 16 (!) pneumatic cylinders to lift the boom. I think an actuator made with 3x11 panels with a 3x3 piston would be great for that kind of model, and the wider piston and longer stroke would make it more robust and realistic.

Yes, I have seen that also. From pneumatic you need such a lot to raise heavy booms.

Panels: for 3x11 panel can make a rounded profile, but it would be 4 stud tall or wide just the inner part. It would be much bigger than mine, but this only means that would be good for very very big machines. I need actuator in this scale (outer shell: 4x3 or 3x3, max. 4x4 stud).

Edited September 18, 2013 by Mbmc