8421 Crane Boom issue

[nychase]

I just finished collected for HANS 8421XL and will be using one of the 100mm ones

http://store.firgell...ts.asp?Cat=1822

Its possible it wont be strong enough to hold the HAN boom in which case I will double them up. The best part about these accuators is that they feature the motor as well as the accuator so its not as expensive as it seems.

Ill let you know how it goes. I hated that I couldn't leave the 8421 "on display", and I lack the ability to create a decent working version of opposed LA's.

I know it seems like I am repeating myself but trust me when I say I have spent the last 3 years looking for an acceptible solution. The Firgelli accuator works very very well for the price since it includes the motor built into such a compact size. Theres another guy thats posted on EB before that made all metal accuators that were designed to connect to Medium and XL motors but hes gone MIA in the last few months.

If there is a strong enough desire for me to build the 8421 with this accuator to show everyone then just voice your opinion and I will get it going so we have a comparison to Alasdair's solution.

I originally purchased the actuators to use on Jennifer Clarkes Baldwin crane which originally used a "lead-screw" which was completely bespoke.

[DarkShadow73]

I am hopeful it will be as close as possible,if not I would think about making a custom LA.

@Alasdair - do you think 1 LA would lift that heavy a boom with it extended as well and not fail with time? I'm no MOC'er like you and many others are on the forum. I may make some simpler ones that I just haven't had the time to take pics of yet, but like in the case of the 8295 Telehandler, that 1 LA struggled with the M-motor and even torquier XL-motor, any telehandler I've ever seen in real life had 2 pistons, one on each side of the boom, even most mobile cranes. Just a thought...no criticism, I will definitely be waiting for your instructions on this mod.

[Alasdair Ryan]

I have found a few bugs witch meant I had to redesign the new upper part.

Now about the weight of the boom....I am using the buggy motor (the most powerfull) to a worm gear so it should be fine......he hopes.....

The 'big' cranes have two rams as it is bigger and can lift more,but since the lego crane is modeled on medium sized crane,one La should be right.

[Alasdair Ryan]

You are now getting a custom La because a lego one is just was not long enough.

Edited November 30, 2012 by Alasdair Ryan

[DarkShadow73]

I have found a few bugs witch meant I had to redesign the new upper part.

Now about the weight of the boom....I am using the buggy motor (the most powerfull) to a worm gear so it should be fine......he hopes.....

The 'big' cranes have two rams as it is bigger and can lift more,but since the lego crane is modeled on medium sized crane,one La should be right.

@Alasdair-

If you compare let's say the 8421, 8053 and 8460/31/38, the 8421 really towers over the rest of them, so I'm (no criticism, please don't take it this way) wondering what a LARGE lego crane would look like, it would have to be a monster...can't wait to see your finished product...

[Alasdair Ryan]

@Alasdair-

If you compare let's say the 8421, 8053 and 8460/31/38, the 8421 really towers over the rest of them, so I'm (no criticism, please don't take it this way) wondering what a LARGE lego crane would look like, it would have to be a monster.

You also have to go by the number of wheels 3 axles is probably going to take you up to the 60 ton mark any heaver than that It will most likely have more axles.

[Technic Gearhead]

I was afraid of the LA being too short, however your solution looks interesting.

The boom looks high enough in your very first image in this thread. Would it go back down all the way flat mounted that way? My guess is that it did not or you might have kept it that way. Keep pushing onward!!

[Alasdair Ryan]

I was afraid of the LA being too short, however your solution looks interesting.

The boom looks high enough in your very first image in this thread. Would it go back down all the way flat mounted that way? My guess is that it did not or you might have kept it that way. Keep pushing onward!!

Yeb that was the problem I could have it the same height raised but it would not lower all the way down or vice-verser.

[DarkShadow73]

You also have to go by the number of wheels 3 axles is probably going to take you up to the 60 ton mark any heaver than that It will most likely have more axles.

@Alasdair -

Very true, hadn't thought of axle count, I indeed have seen some 4 or even 5 axle mobile cranes in real life...

[Alasdair Ryan]

Here is a big crane for you in lego,the boom is transported by another truck in real life. Edited November 30, 2012 by Alasdair Ryan

[DarkShadow73]

Here is a big crane for you in lego,the boom is transported by another truck in real life.

No doubt that's a monster, I've never seen one that large...amazing...if TLG reproduced something like that and added PF or RC, it could easily top out at the highest price Technic set ever, not to mention the highest piece count most likely...

[skylinedan]

LOL< LEGO would never even in a million years come out with something that big, but its pretty damn cool none the less. I have been working on a longer ram just for this kind of build, and yes it won't be a true LEGO part. The purest will complain, but until LEGO get off their butts and come up with something we can use for this application, I,m gonna make my own.

Dan

[Bricktrain]

Here is a big crane for you in lego,the boom is transported by another truck in real life.

Try 32 transporters to transport one with full superlift, 550 tonne configuration. We have one at work.

Lattice boom does not have hydraulics for luffing though so doesnt really apply to this thread. Our Demag AC300 used to use a boom trailer but now has had the axles reconfigured so it is not required by NZ road regs.

Still working on my Grove 5220 model, the full reach is just over 2.4m.

[Alasdair Ryan]

I was not referring to a crane using super lift.

[Bricktrain]

I was not referring to a crane using super lift.

Even without superlift each standard boom section is 3.2m x 3m x12m so is a truckload itself, then there is a butt and tip,

[Alasdair Ryan]

Again you can see cranes with just a ssl version,so the counter-weight and hook are just carried by truck.

Edited November 30, 2012 by Alasdair Ryan

[DarkShadow73]

LOL< LEGO would never even in a million years come out with something that big, but its pretty damn cool none the less. I have been working on a longer ram just for this kind of build, and yes it won't be a true LEGO part. The purest will complain, but until LEGO get off their butts and come up with something we can use for this application, I,m gonna make my own.

Dan

The regular LA's have a longer ram than pneumatic cylinders, but like you said, sometimes you need even a longer ram to do what you need to do, especially for an MOC. I am going to rebuild my 8295 Telehandler and see if I can integrate 2 LA's instead of just the one to see if it helps the lift and thus strain on the XL motor...

[Alasdair Ryan]

So after lots of trail and error (mainly error) I have decided to use one of the ideas I had last year for the custom La Info here.

Hopfully I can post a better update later today.

Edited December 2, 2012 by Alasdair Ryan

[Technic Gearhead]

Your custom LA looks very nice but I'm worried it will be too big visually. I know there isn't much we can do about that except make it as compact as possible. I wonder if we could make the upper mounting bracket on the boom move towards the LA as the LA gets extended. That might actually look bad once you got everything in there that it needed to have to work though. I guess we need some longer LA's too.

[Alasdair Ryan]

So here is the new and improved version of my La.....

It is just about the same size as two pneumatic cylinders are joined together.

[Alasdair Ryan]

So here is a update on progress,yes I am going to need to make my LA longer ,If you don't have a 12 long steering rack I suggest you order one.

The sag you see in the LA will come out one once I make it longer.

Edited December 4, 2012 by Alasdair Ryan

[Technic Gearhead]

More progress! What steering rack is in there currently - 8 or 10? How about a pic in the lowered position?

What do you have planned for the battery box - leave it exposed or maybe partially conceal it with a combination of yellow panels similar to the 8053?

Keep on going with it.

[Alasdair Ryan]

I need to move the boom back along with the drum to keep the weight balanced.

I was thinking of something like this for the back....

I will post a update later tonight.

[DarkShadow73]

Shoot this getting really in-depth with all the extra parts and modifications/ideas, mainly Alasdair (and I thank him for that)...I'm just going to go simplistic and use the beam idea...temporarily snap on a 15L or whatever would be sufficient (I'd have to back through the posts to see, but 1 poster showed a pic of that idea) to keep the boom up and extended for a period of time..then remove the beams when I want to lower/retract it, making sure to pump air back into the pnuematics as the air will have leaked out over a few hours as it always has before and apparently I'm definitely not alone with this irritating issue, then after the cylinders, hoses, and lines are powered back up, just remove the beams and lower/retract the boom...

[Alasdair Ryan]

I will no longer be working on this Mod,I am having to go back to work.