In another active topic on Eurobricks, modifications to the LEGO 42009 Mobile Crane MKII have been discussed. Many of these modifications have been rolled into a single "ultimate" model which has been under discussion for several months with a full instruction project well underway. I felt that it was time that this magnificent model had its own topic. In this topic I will present the history of the model, detail how all the individual functions work one by one, then go through my review of the build process and thoughts on each function. I expect this writing process will take at least several days, so watch this topic for updates, and please feel free to add to the discussion. By the time the review is done, I'm hoping the "final" instructions will also be available for download. Drafts are already available. It all started with Technic set 42009, "Mobile Crane MKII", by far the biggest crane LEGO has ever released and also the largest Technic set ever by part count. You might think this would be enough to satisfy anyone, but you would be wrong. From nearly the day that the set was released, fans around the world were already modifying the set to make it even bigger and better. The first major modification came from Jurgen Krooshoop. His "Ultimate 42009" looks nearly identical to the official set, but instead of having a single motor and a gearbox to switch between them, Jurgen's model featured 8 motors to control all the original motorized functions as well as driving and steering. Any of these could be operated simultaneously. Jurgen was kind enough to produce a full set of professional instructions for his model. The original model features a 3 stage telescoping boom, but the full extension of this boom is not very impressive because there is so much overlap of each section at the stops. Cristophe Moittie solved this problem by creating an extended boom which was nearly the same length as the original when retracted, but was much longer when extended. Instructions for the extended boom were then created by afol1969 here at Eurobricks. Finally, Eurobricks member Gerger decided to extend the cranes 5 axles to 6. While he was at it, he added full independent suspension to every axle. At this time the model no longer resembled 42009 very closely, so Gerger changed the appearance to loosely match the Grove GMK6400 mobile crane. He was kind enough to provide an LDD file of the completed model, and from there (and a couple of design iterations later) various EB members such as myself took over to make an LDraw file, a parts list, and full instructions. Finally, we arrived at this brilliant model: From the outside, you might be tempted to miss how complex this thing is, but from inside you can see the 9 motors and copious mechanical functions. In this color coded image I've produced, you can see the interweaving of all the functions: Red = Drive: 2 XL motors, all 6 axles driven
Blue = Steering: L motor, 5 axles steered
Yellow = Suspension: all 12 wheels independently suspended
Teal = Outrigger Extension: L motor
Brown = Outrigger Lift: L motor
Pink = Slew: M motor, 360 degree rotation
Tan = Boom Luff: L motor, parallel linear actuators
White = Boom Telescope: L motor, 3 stage telescope using cable return
Green = Winch: M motor
At current count, this model features 3504 parts and 199 pages of instructions.