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Well, it's certainly about time I made a work in progress thread for this monstrosity. A while ago, I decided that I wanted to build a 9 axle mobile crane, similar to a Terex AC 1000, with all of the features. I chose the crane for several reasons, including: -The fact that it has star formation outriggers, rather than telescopic ones, which would be easier to make strong. - The Sideways Superlift, or SSL. On the real crane, it is used to maintain tension on the boom, allowing the crane to lift heavier loads. A problem with many Lego cranes is that the booms sag, something I hope this will remedy. -The sheer size of the thing gives more room for including functions, like steering and outriggers. (more on that later) As a model, I want to be able to have: Fully remote control drive and steering Swapable steering modes, from normal to crab steer Automatically deploying outriggers, using only one channel Full crane functions, winch, luff, slew, and boom extension. SSL, to maintain tension on boom Minimum amount of parts to be fitted by hand, instead having everything attached. Lights A red and black Mammoet inspired livery Be able to lift 42009 at minimum radius. Now, with those goals in mind, I made a prototype boom: The colors are awful, but it was a good proof of concept. It weighed 2954 [2366 in revised version.] grams, extended to 263 centimeters long, and was 105 cm retracted. I say was because I took this apart and made version two, which sadly hasn't been photographed yet. This version of the boom uses an XL motor for extension of the first section, operating through a very long drive shaft, a reinforced bevel gear box, and then a worm gear to 40z gear setup. The second section has 2 slaved M motors for power, which operates through a nightmarishly complex gear train, and extends the 3rd and 4th sections together, via a rope system. The SSL spreader mechanism was just as bad, having to operate through a spline shaft. This version had a number of problems, including drivetrains that were needlessly complex, and it weight too much. The new version is lighter and simpler. The boom head. The reel on the side is one of two that operate the 4th boom section, through the pulley system described here: Jennifer Clark also describes this on her site, and it is used in 8421 and 42009. However, I had to actually use string reels, because nothing else was long enough. This is actually my 5th or sixth try at this, because initially I had a motor at each section, but when that proved too complex, I employed this solution. Another snag I hit was getting the 3rd section to extend. I was for a time using a custom gear rack made out of pins, but that ultimately proved to be too unreliable, so I went through my boxes of stuff, and got enough gear racks to make it work. Moving on, this was one of the easy parts. The base of the boom, with the mechanical cylinders that would have elevated it, and the XL motor that extends one of the sections. The LA brackets carry the gears that would have driven the SSL from motors in the superstructure. The SSL The above picture shows the extension mechanism, with 2 u joints to make an awkward connection, and the SSL mechanism. The SSL would have been elevated by a linear actuator, then spread by two small ones. The spreader actuators are driven through a worm gear, which is free to slide along the red 12L axle, maintaining connection to the rest of the drive train at all times. However, this mechanism is over complex and flimsy, meaning that it will receive a redesign. And now, for the pictures of this boom fully extended: So far, the boom is mostly complete, and I have prototypes for most sub systems, so this should be great once finished. Progress Edit: I have made some progress on this project, namely working out some of the stuff involved with the outriggers. The below picture is a mockup of the crane on the turntable, with all the wheels in their correct locations. The lime beams in the foreground are my width guide for when I'm building axles. The crane is going to be about 23 studs wide when complete. Most of the outrigger is figured out, but now my real challenge is figuring out how to integrate the superstructure and the lifting cylinders. Below is a picture of the outrigger mechanism as it is complete right now. More Progress: I have built most of the superstructure that holds the boom. It is made with some Znap truss pieces, and is quite strong. Also shown is the chain drive, which switches on a set of recievers in the superstructure. The winches and all that will go behind this unit, on a piece that is detachable, for ease of transport. Slowly, but surely, this project is coming along. Be patient.
