[MOC] Dragline excavator w transport and instructions

[Ivan_M]

Backstory:
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.

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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.

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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:

 

Edited August 31, 2018 by Ivan_M

[Beck]

Very nice models! I saw a pf wire connected to the dragline excavator while unloading. Is this connected to the power source for unloading? Also, why did you choose a US style trailer for this combo? 

[Aventador2004]

Very well made and nicely presented. Great work overall.

[mpj]

Excellent work, I enjoyed very much reading the full story. I also appreciate how did you scale correctly the models, following drawings of real machines.

[Ivan_M]

7 hours ago, Beck said:

Very nice models! I saw a pf wire connected to the dragline excavator while unloading. Is this connected to the power source for unloading? Also, why did you choose a US style trailer for this combo? 

Thank you. The BB is in counterweight and that is not attached during transport/unloading. It would look weird and the whole superstucture leans too much back when it is not balanced by boom

Counterweight

As for the trailer - mostly becuase it is much simplier. Low loaders in Europe are usually with steerable wheels and I was running low on key parts

[Cumulonimbus]

That is a really good looking crane @Ivan_M. It reminds me of my 42042 redesign and I like that we had similar ideas I: the use of the BWE stickers for the counterweight, the adjustable track width, the modularity of the boom, etc. I would have like to see that changing the track width did not require a partial rebuild but is realized by a linear movement, but I understand that this might compromise the rigidity of the carrier too much at this scale.

You mention the lack of a free-fall function and I wonder why you eliminated this feature? In my model I have built in linked clutches on two of the three winches, specifically for a dragline configuration. These clutches are spring loaded, so normally they are engaged and transfer power from the gearbox to the winch. When a lever is pushed, the clutches disengage and the two drums can rotate freely under their load and the bucket can drop.

[Ivan_M]

 

1 hour ago, Cumulonimbus said:

...

Thank you. You are right about the undercarrige rigidity. You also have to consider that the range of movement is quite big so the mechanism would have to rely on brick build accurator or some linkage - not very space efficient.

The lack of free fall winch is most probably lack of my skill. I would love to see your solution if it is possible. I also wanted to keep it fully RC, I'm not sure if that is your case.

[Cumulonimbus]

5 hours ago, Ivan_M said:

... I would love to see your solution if it is possible. I also wanted to keep it fully RC, I'm not sure if that is your case.

My version works like the original 42042: PF powered but manually operated by two-way switches. My crane is a similar scale as the 42042 set, so it is smaller than yours. The image below shows my cranes drivetrain, colored according to the functions. Not sure if it is clear enough, but the orange components are part of the free-fall mechanism. Pushing the lever sticking up between the switches (not shown here), releases the two clutches in the drivetrains of the blue and green winch. The spring buried in the middle re-engages the clutches when the lever is released. The yellow winch which controls the boom angle can never be decoupled for obvious reasons.

I only have one issue with this crane and that is the gear ratios. The total gear reduction caused by the worm gears, diameter of the winch axles and the power transmission from the PF motor to the gearbox is too large, so the lifting speed is glacial. I'm still working on that.

 

[Ivan_M]

That is the way I have tried, but abandonded very early for two reasons - I wanted to keep only 3 IR receivers and I wanted to stay fully RC. Beside that there was no space. I wanted BIG winches, with 36T bewel gears on side as they look very nice that way. In real machine the winches are also massive and they are almost fully inside the body. I was not able to sink them that low unfortuntally. Here is color coded drivetrain:

dragline gearing #1

The superstucture ends with L motors and all M motors are also at the edge.IR receivers are above L motors. The front had to stay quite empty to fit cabin. What I regret is that the front most winch is smaller and not aligned with other two like this:

[ArsMan064]

Amazing moc! I really like crane and truck. Both model looks very well

[tw2ka]

Beautiful moc! Amazing how you got the shapes so close to the original with all the functions. 

[BusterHaus]

Excellent work, the boom is my favorite part, followed closely by the truck.  Both are very eye-catching.  The excavator has some great details too, like the bucket and the cabin.

Do you think the track width conversion mechanism is possible at this scale?

[lcvisser]

Very nice!  I really like the combination and especially that you took a lot of care to have matching scales. Each of the three components is a great MOC by itself. Great job  (It reminds me a bit of a very improved version of one of my all-time favorites, 8872 )

On 8/29/2018 at 12:25 AM, Beck said:

Also, why did you choose a US style trailer for this combo? 

Just out of curiosity, what's the difference between US and non-US style trailers?

[Ivan_M]

7 hours ago, BusterHaus said:

Excellent work, the boom is my favorite part, followed closely by the truck.  Both are very eye-catching.  The excavator has some great details too, like the bucket and the cabin.

Do you think the track width conversion mechanism is possible at this scale?

Thank you! Boom is my favourite part as well. I think it is possible to have tracks with various width mechanism, but certainly with some drawbacks like larger middle section or tracks not beeing wide enough in extended mode. Maybe next time :-)

1 hour ago, Ludo Visser said:

Very nice!  I really like the combination and especially that you took a lot of care to have matching scales. Each of the three components is a great MOC by itself. Great job  (It reminds me a bit of a very improved version of one of my all-time favorites, 8872 )

Just out of curiosity, what's the difference between US and non-US style trailers?

Thank you! I think the main difference is that in US roads/streets are wider so there is no need for steered axles. I don't think roundabounts are used in US as well

[terryli]

Awesome creation! Can't wait to build it. When the instructions will be avaliable? 

Thanks and appreciated!

[AFOLegofan66]

Very nice crane... reminds me of the drag line crane of @designer-han. Well done and thanks for making instructions. Well priced for all the work you put in this project !!

[Ivan_M]

9 hours ago, terryli said:

Awesome creation! Can't wait to build it. When the instructions will be avaliable? 

Thanks and appreciated!

Thank you! I have already submitted it to rebrickable, it is in the process of validating. I hope it will be published soon.

 

7 hours ago, AFOLegofan66 said:

Very nice crane... reminds me of the drag line crane of @designer-han. Well done and thanks for making instructions. Well priced for all the work you put in this project !!

Thank you. I mention it in first paragraph, Designer-han's dragline is one of my most favourite crations and reason I have build this one

[zux]

Wow, it is not just one but three great MOCs. I really like the effort you put into details not just to function but also look great.

[Ivan_M]

Thank you for your kind words. Dragline is published on Rebrickable:

https://rebrickable.com/mocs/MOC-17193/Ivan_M/dragline-excavator/#parts

[gate]

Amazing job, props to you @Ivan_M for detalization and keeping the scale. I have to learn from you.

And it's always nice to see more tracked vehicles! As for playability - it's fine if you ask me. Usually one doesn't play it 24/7, as many other construction machniery as well, but it looks really cool on the shelf.

[1gor]

Very nice small size combination  it could fit Mack Anthem perfectly IMHO.

[Ivan_M]

Truck is finally published on Rebrickable:

https://rebrickable.com/mocs/MOC-17197/Ivan_M/8x4-heavy-duty-truck-rc/

lowloader is in progress, I think I will finish it before end of the week.

[Ivan_M]

Lowloader is also finished:

https://rebrickable.com/mocs/MOC-17382/Ivan_M/lowloader/