Technic Builder

Intro and Giant Mobile Crane build thread

Recommended Posts

Hey everyone. I've been registered on Eurobricks for ~ 1.5 years under a different account, but I decided to standardize all my lego related stuff across one gmail, youtube, and Eurobricks account (and blog URL of which there is nothing on it). My other account here only had 12 posts anyway, so no big loss.

I'm making this build thread because I wanted to share the progress I've made so far on the giant mobile crane I'm building. I refer to it as a "giant mobile crane" because it's not replica of an existing crane. If you were to compare it to anything it would be a chassis similar to the Liebherr LTM 11200 9.1, with the outriggers of the LG1750. The main boom WILL NOT lift or operate like a traditional mobile crane boom. The reason for this, is that at this scale I don't feel lego does well in cantilever. Instead, the boom I'm building will be 4-5 seconds, each section being at least a meter in length but they will only extend straight up. At the top of the boom will be a short (less than a meter), but stout lattice luffing jib. The turntable for the boom will be at the TOP of the boom and not at the bottom like most mobile cranes. Even if I make the most stable reinforced turntable I can think of, I don't think putting it at the bottom of 5-6 meters of lego is a good idea. There will be the issue of what counterweight system makes the most sense for a crane of this type. Haven't figured that out yet. If this crane really existed it would be special use to erect wind turbines. The crane has a lot of height and decent lifting capacity, but only at short radii.

The other main difference is instead of two hydraulic pistons (well, the lego equivalent is two gear rack pistons, or two string extended pistons) the main boom will be lifted by a collapsing triangle. Imagine the boom laying horizontally, then imagine a stout A frame also laying horizontally but connected to the mid-point (or slightly above the mid-point) of the boom. The bottom of the A-frame and the bottom of the boom are connected with string. As the string gets shorter the triangle collapses and the boom is forced upwards. Since string can handle lots of tension and it's easy to create a pulley system I think even an extremely heavy boom (40 pounds?) can be lifted without straining the legos too much. The legos mostly undergo compression under lifting which they should handle just fine.

The color scheme for the crane is yellow with black trim and L bley panels for the deck (because I have a lot of those heh). I'm a real sucker for standard Technic yellow and black.

Key features / functions of the crane. The starred ones I'm not sure about yet.

1. All wheel steering

2. Two steering modes (minimum turning circle and crab steering)

3. Third steering mode of reduced rear axle turning (for city driving)***

4. Fourth steering mode of rear axles locked (for highway driving)***

5. All wheel independent suspension

6. Pneumatically adjustable suspension (technically when one pneumatic cylinder compresses it affects the others, but not that much so I'd still call it independant suspension)

7. 4 speed gearbox

8. 3 speed gearbox plus reverse and a one-way clutch***

9. Giant outriggers that extend, telescope, and deploy.

10. Giant outriggers that with the help of other non-telescoping or extending outriggers near the front and rear of the vehicle lift the vehicle from the ground.***

11. Pneumatic outriggers*** (I have enough LA's already, but I'd have to buy a LOT of pneumatic cylinders to do it pneumatically. . .not sure if I want to do that)***

12. Brake Lights

13 Turn signals

14. Turn signals that are properly synchronized in the front and rear of the vehicle*** (I know I can get them in the vehicle but not sure if I can make them sync up)

15. Low beams

16. High beams

17. Working steering wheel

18. At least a few other MISC cabin features (adjustable seats, locking doors - windshield wipers would be a fun one if I have space for another motor)

18. The fake engine will be a compressor made of 6x small pumps. I don't think I'll include the standard Technic fake engine. That compressor will be used for the suspension, and potentially to pneumatically lock the boom in a vertical position.

19. Full RC except for high and low beams and windshield wipers or any other vanity features added (flashing lights, etc)

For the boom and crane:

1. The boom, jib, and counterweight assembly will be detachable from the vehicle. All electronic systems will be separate. In real life, for a crane like this the boom would be brought in on a separate truck. I currently don't have any plans to make a a truck (but who knows. . . ). I'll probably "cheat" and place the boom on top of my model with my hands, but no other connections will need to be made.

2. The boom will be at least 4 and possibly 5 sections. Not sure exactly how long each will be.

3. The boom will be erected by a collapsing triangle pulled together by string.

4. The boom will extend up one section at a time and each section will lock in place. The "ram" that will extend each boom will also be string powered.

5. For the ram that extends the boom I'd like for it to run at a slow speed when lifting, and a very fast speed when descending***. I think this can be done with differentials.

6. The same motors that erect the boom might also extend the boom*** (probably 4x XL motors)

7. The turn table for the boom will have at least 3x bearings. A large ring bearing at the top, and then two. . . .are they trust bearings? I forget the word. . .but anyway, two additional bearings that extend down into the boom to keep the upper rotating structure stiff in all directions (I HATE slop)

8. The counterweight assembly will automatically unfold into the correct orientation under the force of gravity. ***

9. If that doesn't work I'll use LA's to position and lock things into place.

10. The luffing jib will luff of course.

11. The main winch I'm hoping can lift at least ~ 10 pounds. The max weight will be mostly contingent on how I design the counterweight system.

Well, that's about all I can think of for now. I'm sure you can read all that and say "whatever. . . who is this guy. . . he really thinks he can build that?" I really think I can. It will take a long time, but I'll get it done. I have an engineering mindset and I understand simple mechanics extremely well. When I was a kid (maybe 10 or so) I built a mechanism similar to the automatic axle sorter, but alas I have no record of it (this was before digital cameras and I never thought to photograph my stuff). While I did take a long break from building with Legos, and Technic changed from studded to studless during that time period, I still grasp this stuff really well.

Ohhh yeah and a little about me. I'm 30, I'm married (my wife supports my hobby as long as I start writing about it). I coach triathletes and cyclists. I'm in the twilight of my photography career (in fact, I probably shot my last event earlier today). I work from home so I have a lot of time to build. I have two cats which will one day knock over one of my lego drawers for sure. I live near Atlanta, GA. I went to Georgia Tech, but I have a Business Management degree, not an Mechanical Engineering degree (ohhh well. . . I never could have held an office job anyway). I swam in college and I still compete in triathlons and bike races.

Here are three videos with a tour of my lego room, an explanation of the steering of the crane, and an explanation of the drivetrain. I WILL get better at making videos as time goes on. First time you do anything you're the worst at it you ever are. That's the first time I've made a lego video, so they're the worst ones I'll ever make. In the future I'll edit them. While I have worked as a photographer, and I even worked on a movie for 2 months, I haven't created many videos for my own purposes.

Also, here's a link to where I'll dump periodic pictures of my build. You can see a failed design path I went down a long time ago as well as some of odds and ends.

http://www.sammorgan...26491&k=7pzdqqw

Share this post


Link to post
Share on other sites

This is going to be an amazing crane if you manage to fit everything into it that you listed above. :sweet:

I noticed that on your axle setup your pivot point of the portal axle is wrong which is why you had to make a 2,1/2 long axle.

The middle of the universal joint should be in line with where the portal hub pivots.

Share this post


Link to post
Share on other sites

Welcome. Sounds a very interesting crane. I have been working for a crane company for 2 years now and have still not completed my six axle model I was building before I started there. I have added several new features though that are found on real cranes. I wish I was at home more so I can do more building, working 80+ hours a week and being away for six months of the year doesnt help my building progress. I look forward to seeing how you cope with some of the difficulties that I have struck.

Paul.

Share this post


Link to post
Share on other sites

WOW, looks like it will be awesome! :thumbup: I don't think the u-joints will be a problem as he's using CV joints for the other pivot.

Share this post


Link to post
Share on other sites

thats a lot of stuff, i am also working on sorting everything out butt that takes a while. and i also do triathlon :laugh:

Share this post


Link to post
Share on other sites

That's awesome!

I don't want to sound negative, but which features will you sacrifice if not everything can be fitted in that crane? How long would you go in modding Lego parts?

Share this post


Link to post
Share on other sites

That's awesome!

I don't want to sound negative, but which features will you sacrifice if not everything can be fitted in that crane? How long would you go in modding Lego parts?

The only other part I might modify is to drill out some wedge belts (pulley wheels? Whatever they're called) so they can spin freely on the same axle.

I'm using non-lego string, and I have non-lego pneumatic tubing (but I also have lots of lego pneumatic tubing, so I might not need it).

For the battery packs I'm REALLY thinking about making my own custom 8 cell rechargeable packs. I'm not a fan of the performance of the motors on 7.4 volts, but I'm not going to feed this crane endless AA non-rechargeable batteries. The other big reason for using non-lego battery packs is I think each lego pack has some kind of current limiting functionality either by a thermistor or some other mechanism. I'd be annoyed if my batteries are capable of putting out 4 amps (just a guess) but the Thermistor limits the pack to 2 amps. There's a guy who's figured all this stuff out and his site is in my favorites somewhere.

As far as features I might cut they're the ones listed with *** by them. All the others with no *** I will find a way to include.

Edited by Technic Builder

Share this post


Link to post
Share on other sites

There's a guy who's figured all this stuff out and his site is in my favorites somewhere.

Yeb his name is Philo, he is a member here.

I just call him "the made french man" don't ask me why.

His site

Edited by Alasdair Ryan

Share this post


Link to post
Share on other sites

Yeb his name is Philo, he is a member here.

I just call him "the made french man" don't ask me why.

His site

Yeah 750ma per battery pack - I'll either be shunting existing battery packs, or cannibalizing existing battery pack output connectors and making 7 or 8 cell NiMH packs of my own. I have a bunch of V2 receivers so I don't want to be dealing with current limitations at the battery pack.

Share this post


Link to post
Share on other sites

That's an ambitious project! *oh2* And YES you need pneumatic outriggers. And pneumatic everything else. :grin:

Edited by TwentyLeggedHen

Share this post


Link to post
Share on other sites

I think you might have an issue with the CV joints popping out, Ive had much lighter builds and they disconnect all the time. They just don't work to well for drive

Share this post


Link to post
Share on other sites

What you're building sounds like a Grove GTK 1100:

GTK2.jpg

Except, your crane won't be mounted on a trailer, but a regular crane base.

More info in this article: http://www.vertikal....ews/story/5116/

Also, I'm building a nine axle crane with crab steer, so you might want to follow along with how I'm making that work.

Share this post


Link to post
Share on other sites

Also, I'm building a nine axle crane with crab steer, so you might want to follow along with how I'm making that work.

Thanks a lot for the link. I was completely unfamiliar with that crane. The support guide wires was something I thought about for my model. Looks like they are in fact used in real life.

Do you have a direct link to a thread (or website) on your 9 axle crane?

Share this post


Link to post
Share on other sites

That sounds (and looks) like a very nice moc. I hope you will be able to finish it (not to question your building skills, but building on this size has its disadvantages :wink: ).

I'll keep an eye on this topic to see the progress :classic:

Share this post


Link to post
Share on other sites

I was out of town for Thanksgiving for 5 days and I also had some work to do, so it doesn't look like I've actually built that much, but I've had a lot of time to think about the project.

In a nutshell:

Gotta re-do some of the gearing for the steering, but I expected this.

I can do 3 steering modes for sure

I think I can also do the 4 speed transmission but I definitely won't be doing a clutch or 3 + R, just 4 speeds

Pneumatic functions will be:

Suspension lifting (I won't include return lines to lower the suspension - gravity will do this. If the wheels get off the ground when the crane is lifted with the outriggers the mini cylinders are not strong enough to compress the two weak springs plus lift the weight of the wheels, so I won't include the return lines)

Pneumatically shifted steering mode (between crab steer and minimum turning radius mode. The 3rd mode will probably be shifted via a motor

Maybe Pneumatic widening of the outriggers. I'd probably need two cylinders per arm. The biggest problem is that as air leaks over time you'd be able to push them in by hand - unless they're constantly topped off. 2nd issue is I don't want them to swing out too fast. I think LA's would probably work better for this function.

The next hard thing is going ot be implementing the XL motors for drive connected to a 4 speed transmission. I have space (an area of ~ 11x11x25 studs), but it's more of an issue of figuring out the best way to do things.

Ohhh yeah, and I don't have to run any wires through the main body of the crane. Each area where I have motors will have space for battery packs and receivers.

Lastly, I'm going to cheat and make my own 8 AA NiHM battery packs. I have a lot of the regular lego battery packs and I'm going to steal the connectors off them and solder them on to the other packs. This gets me 9.6 volts rechargeable, and I bypass current limiting.

I made a video. 10 minutes flies by. I know if I edited I could get the duration down, but that takes too long for now. Brickfair Alabama is coming up, and I'm out of town again for ~ 2 weeks around Christmas. I'd like to have at least the chassis completed by then so I can display a work in progress.

Tell me what you want to see more or less of in these videos.

Edited by Technic Builder

Share this post


Link to post
Share on other sites

LOL, love the cat voice over intro. I have 2 cats myself, but they aren't that big yet. Looking forward to seeing your giant mobile crane completion.

Share this post


Link to post
Share on other sites

Does your cat spill your Legos on the ground? Mine still thinks it's hilarious even though she is 13 years old :P

Share this post


Link to post
Share on other sites

I had a good laugh watching your second or third video, when you pulled out the needle nose pliers. Might get some purist noses out of joint :laugh::thumbup: I myself have a small pair as well...

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.