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Intro and Giant Mobile Crane build thread
Technic Builder posted a topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
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