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Ivan_M posted a topic in LEGO Technic and Model TeamBackstory: Ever since I emerged from my dark age I was mesmerized by Designer Han’s models – especially dragline excavator. I like all kind of excavators so I was slowly gathering pieces for it to buy instructions and build it. I have realized over the time that building from instructions is not entertaining for me and that I can build almost anything if I have the drive (and parts). I still admire Han’s models, but I know that I would be disappointed because of his design choices. Don’t get me wrong – I still like his work, but I don’t want to build it anymore. Long story short – I wanted my own dragline excavator with truck transport. Preparations: First of all I had to pick a reference machine, in this case Sennebogen HD 670 tracked crane. Why this one? Sennebogen because it is not very known and because of this fantastic die cast model: http://www.cranesetc.co.uk/library/rosreviews/203/203review.htm . Such models are very good because you can see the machine from a lot of angles and you can replicate small details from them more easily. The model is however 690HD and I have picked smaller 70 ton 670HD. This is because of whole concept with transport truck. The scale is dictated by wheels, in this case by wheels on truck and wheels on excavator as well. Since TLG is making only two wheels for tracked vehicles it is simple choice. With bigger tracked wheels the scale is 21,5:1, meaning that 49,5mm tires for truck are perfect fit. 690HD with the same wheels would be closer to 23:1 and we do not have truck wheels for this scale. Features: Undercarriage Real crawlers have either retractable tracks or dismount them completely when transported. In order to achieve that I had to place all motors to superstructure and use single battery box. As you can see from datasheet, the tracks can be retracted so they are not wider than body. To replicate it I have built it in such way that both tracks are very easily detachable from central piece that can be swapped for narrow one. Replacing this central piece doesn’t take more than few minutes, it is only necessary to take apart two liftarms on each side as seen in the picture. Another stud or two narrower tracks would be probably better, but I would certainly lose the ability to swap it easily. All four wheels are driven by two shafts from superstructure connected to M motors; final ratio is 9,265:1. Wide track Narrow track IMGP5236 Superstructure The superstructure holds six motors (4x M-motor and 2x L-motor) – two M motors are for tracks, 1x M motor is for slewing via worm gear on turntable (56:1) and rest are for winches. Slewing gave me quite a headache because of the desired gear ratio. The real machine can rotate up to 4 revolutions per minute so I wanted to replicate that. In the end the only viable solution was to use older turntable driven by worn gear without further gear reductions. I use train PF remote to start and stop smoothly. The usage of older turntable meant I had to shorten boom because of its less stability as it bends significantly more than new type. The A frame is fixed – the boom is raised by pulling floating pulleys with attached ropes. Bigger machines uses movable A frame where the angle between A frame and boom is fixed. The A frame can be folded down when the crawler is transported. A frame is Pythagorean triplet with beams length 29-21-20. There are 3 winches for boom raising, bucket lifting and bucket drag. All three are equally geared 5:1. Counterweight is detachable as on real machine, it of course holds standard Technic battery box. Cabin features opening doors and foldable walkway. IMGP5220 IMGP5222 Ready for work side by side Boom Booms on real machines are made out of several truss elements bolted together. There is usually lower boom section that stays on crawler when transported, then are intermediate sections in various lengths (2,9m, 5,7, and 11,2m) and then headpiece section. I wanted to replicate this kind of boom so I focused on correct shape of each section and size as well. This mean that the lower boom section is pyramid-shape: 5x1 studs wide at crawler side and 9x9 studs at opposite end. I guess not all connections on it are TLG legal, but everything fits nicely without any stress and thanks to it truss-like constructions it is very sturdy. The same principle follows at intermediate section, in my case the shortest one (2920 mm => 17 studs). Boom ends with headpiece that is quite similar to lower section but ends with two pulleys. They are of course not real pulleys as TLG doesn’t make anything free-spinning in that size but size was more important to me. The drawback of such modular boom is its weight; it is almost double the weight of boom that would be built in one piece so I had to stay low with total length. There are also two pulleys serving as fairlead so the rope dragging the bucket goes to winch from top, the fairlead pulleys are mounted on lever so they stay in same position regardless of boom angle. Headpiece side comparsion boom Bucket It is brick-build and its size is only guessed from pictures and its volume, I was unable to find any datasheets with buckets. Bucket Greebling, look and difficulties As usually I pay a lot of attention to greebling like railings, mirrors, cabin shape, lights and other small details. I really had fun with this model as it is quite packed with it. The biggest obstacle during the build was constant lack of parts. Together with truck and low-loader it is reaching 4000 pieces and I was even running low on both 2l and 3l pins once. I had selected yellow color at the start, green would be certainly better for Sennebogen, but I already had some yellow parts and green technic is very expensive. Beside that I have seen pictures of Sennebogen machines in various colors like yellow, red and blue, so I think it is fine. The whole internal build is very symmetric; the only asymmetric is gearing on left side for slewing and gearing on right for drag winch. IMGP5223 Playability Honestly, playability sucks. There is one important feature of real dragline omitted – free fall winches. Without it you can place bucket too close and drag it only few centimeters. Grabbing anything with the bucket is also very difficult. Drive and slew works very well though. Truck The truck is very loosely based on this real counterpart: http://www.ditzj.de/html/en/trucks/scania/wiesbr500.html i.e. 8x4 tractor with short wheelbase, 2 steered axles, high cabin and tower behind it. It is driven by L-motor and servo is used for steering. Both steerable axles use the same configuration like in my previous truck – 5l steering arms and hubs with 3 ball joints. There is of course Ackermann steering and different angle on both axles. Rear axles are connected to fake V6 engine. Cabin features two seats, IR receiver between them and steering wheel. Whole cabin can tilt to reveal engine. Gear ratio from L motor is 7:1 because it is meant to haul quite a lot of weight. The truck can be easily modified to low cabin version as the high roof is only held by four pins. The tower is too high then so it is replaced with bare battery box. The whole truck is quite heavy on front and it have sometimes trouble with driving when it is without load so it is possible to add ballast box on its fifth wheel. There is also coupling for draw ball trailer, but it is not meant for pulling. I think the most difficult part of design was not to copy my previous truck. The cabin is still quite similar, I’m aware of that, but in the end I’m happy with other small details that makes it different – flags on front, mud flaps, detachable roof, etc. IMGP5248 IMGP5249 Working fake engine Low cabin Ballast box Low-loader Low loader with detachable gooseneck is based on Motomat’s trailer because in the end you realize there is only one viable way how to build it – two technic beams with plates between. A little challenge was how to mount wheels without using single axle for both sides. The frame between wheels can be only 4 studs wide meaning the axle can be supported by 2 studs. I have used 8L axle with stop supported by thin liftarms. In the end the wheels are supported enough, they can rotate freely and you can take them apart without axle. IMGP5260 Lowloader with detachable gooseneck Instructions I have made instructions for dragline and truck as well. Lowloader will follow soon. Both will appear on Rebrickable soon, I will add link here later. Due to amount of work it took I will sell instructions for dragline for 10€ and truck for 5€. Lowloader will be free as it is not something trully mine. Both instructions are as usually PDF generated by LPub3D. Especially the dragline is compressed into as few steps as possible, with only 115 pages (~2400 parts), so if you don't like TLG instructions for beeing too easy this might be something for you. Dragline rebrickable link: https://rebrickable.com/mocs/MOC-17193/Ivan_M/dragline-excavator/#parts Video & gallery Whole gallery is here: https://flic.kr/s/aHskDJiTT8 And one crappy video for end:
Hi guys I am working on a massive walking dragline. If you don't know what a dragline is, they are usually used for coal, oil, and tar mining above the surface. Mine will have a gearbox for switching functions which will use an L motor, an XL motor for lifting the main boom and for rotating the structure. It will have an L motor for the drag rope and for one of the feet, finally another L motor for the hoist rope and for the other foot. I have already completed the main boom. I cannot upload any pictures of it yet because I am on vacation skiing without my LEGO, you will all need to wait until Sunday or Saturday. :( If you don't know what a dragline is, well look it up!!