[WIP] Rough terrain crane MKII

[suffocation]

I wasn't pleased with my first rough terrain crane, so I'm redesigning and rebuilding it from scratch.

I've got a very rudimental carrier chassis done for now.

Current features:

- 4x4 drive (4 L motors geared down 1:11.67)
- four-mode steering (2 servo motors): front-wheel steering, rear-wheel steering, four-wheel countersteering, four-wheel crab steering
- independent suspension
- 2-stage outriggers (1 L motor)
- fake 6-cylinder inline engine

Typically, rough terrain cranes have floating axles, which I find rather hard to implement in a model like this without compromosing rigidity and proportions. My previous crane had long-travel pendular axles that worked flawlessly but also took up a lot of space, so I decided to go with independent suspension. It's far from realistic but it allows for a lower, tougher chassis.

A previous version of the chassis had planetary hubs but they caused far too much friction, so I had to ditch them and gear down more before the differentials. I hope this doesn't come back to bite me in the rear end when the model's done with all its sweet weight. The hubs are loosely based on Didumos' Greyhound hubs. Portal hubs are out of the question. (Those grey 2L half liftarms are temporary.) Tyres will most likely be these: https://www.amazon.it/dp/B07FCLHXBZ/ref=pe_3310731_189395851_TE_3p_dp_1

Edited September 12, 2018 by suffocation

[1gor]

It looks very stiff and Inline 6 is (IMHO) logical choice 

About tire; I prefer original LEGO tires, but who knows, perhaps one day I find 3rd party tires that will perfect...

[suffocation]

On 9/12/2018 at 8:55 AM, I_Igor said:

It looks very stiff and Inline 6 is (IMHO) logical choice 

Indeed, I read some product sheets by Tadano and LIebherr and couldn't find a single model with a V engine. I guess 42082 has one because it looks cool, which is understandable from a marketing point of view.

As for the stiffness, I tried placing three 1 KG weights on the chassis and didn't notice any sagging, so that's good. The combination of O frames, dogbones, L motors and servos works really well.

On 9/12/2018 at 8:55 AM, I_Igor said:

tire; I prefer original LEGO tires, but who knows, perhaps one day I find 3rd party tires that will perfect...

I really wanted to use Claas tyres but I think they look too small. This is what it looks like with the third-party tyres I linked above:

A quick test revealed three welcome positives:

- there's no need for four shocks per wheel. In fact, with three KGs on top and just two shocks per wheel, they compress about one-third of the way. It's all about the mounting point (ahem Bugatti ahem)

- the drivetrain works even with all that load on top. Since I plan on keeping the model a lot less panelled up, with more guts showing, I doubt I'll be adding that much weight on top anyway

- the outriggers work quickly and flawlessly. I can't imagine why the outriggers on 42082 were geared down so much since they still won't lift the model.

And one huge negative:

- the custom hubs refuse to hold up under all that weight when the model is being driven, so I'll have to come up with something else.

 

Edited January 26, 2019 by suffocation

[1gor]

Somehow I'm starting to like Unimog tires on industry mocs, but I understand that CLAAS tired are not perfect because they have tread for tractors, combine harvesters and forest equipment and they are not IMHO first choice for cranes. Look at this side - now you have opportunity to fix all "mistakes" made with previous version.

To me it looks like on 42082 all functions are working approximately on same speed so perhaps this was the reason, but I could be wrong.

I have feeling that this crane would be massive and could end up really good, so I'll keep my fingers crossed

[aminnich]

I love to see a failure (as you put it) and then the following motivation to rebuild it into something greater!  I will follow with interest, good luck.  

[1974]

I think you're off to a wrong foot here, imho

No actual real life "rough terrain" crane have double wishbone suspension and outriggers like that

Now, it can be rather difficult to make outriggers that actually work properly

TLG did fine with 8460 (the setup you partly copied) and failed with 42009 (more realistic but doesn't actually work)

But I think as this scale a proper classic "horizontal out + vertical down" type of outriggers should be doable. You got the scale and probably also the parts to do it

I'd much rather see that working than any type of suspension (which is rather boring on this type of vehicle)

Kudos for the straight 6L though, because that is what these machines often have

[gate]

At this point, it looks great!

Having a turret in the center solves a lot of problems for a crane really, but kind of limits the length of arrow, interesting to see what you come up with here.

Outriggers should work and do its function, that's only thing that matters imho. Horizontal, vertical, 2 or 1 stage outriggers is really not that important.

The tires look awesome

[suffocation]

2 hours ago, 1974 said:

No actual real life "rough terrain" crane have double wishbone suspension and outriggers like that

Thanks for the feedback

As I stated in the first post, I'm aware that this type of vehicle typically has live axles. However, any kind of live axle setup is going to either take up a ton of space or compromise the model's rigidity, which is much more important to me than a "realistic" suspension setup. I already used a pendular suspension setup on my first crane and, while very effective, it took up a lot of room.

As for the outriggers, I actually had the 42070 setup in mind - never was even aware of 8460 - but wanted the stabilisers to extend much farther out, hence the hybrid solution. My solution goes from 27 studs retracted to 64 extended - I'm not sure that kind of reach is feasible with a typical two-stage solution without the end result being flimsy and/or taking up too much space, and/or compromising on clearance, and/or perhaps resorting to pneumatics which I'd rather avoid here. I'd be quite happy to be proven wrong.

[1gor]

This link shows RTC axles, so it could help you a bit...

https://images.cranenetwork.com/cn/cranes/image/IMG_52931.jpg

[suffocation]

Thanks, Igor

The carrier chassis is ready - before moving on to the bodywork, I have to figure out what livery to give this bad boy. Since I want the green engine to be well in sight and the outriggers are pretty much stuck in grey (I have the gear racks in red but I don't want this thing to look like a Christmas tree), what would you guys recommend? I was thinking a mostly black carrier and a mostly yellow superstructure. I tried mounting the superstructure from my crawler crane to see what it might more or less look like:

So, a couple of questions:

1) Do you think a mostly black carrier plus green engine plus LBG/DBG outriggers plus mostly yellow superstructure livery would look decent or is it a recipe for colour vomit? Please help out a colourblind lowcarder.

2) Does the boom need to be longer?

Thanks for any feedback

[1gor]

You're welcome 

IMHO black carrier is best color that would go with green engine and yellow superstructure and  for boom honestly I'll have to see blueprint of your inspiration to be smarter...

[suffocation]

Hi Igor,

I'm not really following a blueprint of any sort - I'm just going by what might look good

If you were designing an RTC from scratch, would you make the boom longer, shorter or keep it as it is in the picture? As it is, it has a dozen studs overhang.

[suffocation]

First, very tentative bodywork tries. Not too pleased but I just can't seem to improve here

 

[BrickbyBrickTechnic]

Not bad, looks much better than mine

Your front/fenders are nicely done, but your middle panels (between the wheels) are lacking size and depth.

[1gor]

Looks very good indeed 

[suffocation]

8 hours ago, BrickbyBrickTechnic said:

Not bad, looks much better than mine

Your front/fenders are nicely done, but your middle panels (between the wheels) are lacking size and depth.

Thanks! I dunno, I really like how yours turned out, especially the front-to-rear flow.

The sides definitely need a lot of work. I'm not sure how much room I'll have there after adding battery boxes or BuWizzes and Sbricks

5 hours ago, I_Igor said:

Looks very good indeed 

Thanks, Igor! Don't you think the front is a bit flat, or at least a bit "overbricked" compared to the mass of gears and the engine right behind it?

[1gor]

No, front is just fine and simple how it is on real cranes. Only designers for modern cars have this unnatural lines and forms...

You have only ti much free space between wheels like @BrickbyBrickTechnic mentioned

Edited September 25, 2018 by I_Igor

[gate]

On 9/15/2018 at 2:21 AM, suffocation said:

1) Do you think a mostly black carrier plus green engine plus LBG/DBG outriggers plus mostly yellow superstructure livery would look decent or is it a recipe for colour vomit? Please help out a colourblind lowcarder.

2) Does the boom need to be longer?

1)It is a common practice to make chassis and other decorative elements in one color and the "dangerous" crane structures and outriggers in the other bright colour, so I feel like you should stick to those 2-3 colours max.

2)From the looks of it, if it is longer that would be really swooping into the eyes, but the real cranes seem to have longer boom, roughly for a half-length of the crane itself.

Hope that helps

[suffocation]

On 9/25/2018 at 7:49 AM, I_Igor said:

No, front is just fine and simple how it is on real cranes. Only designers for modern cars have this unnatural lines and forms...

You have only ti much free space between wheels like @BrickbyBrickTechnic mentioned

Thanks again, Igor Funny thing is, I knew something was off with the front and I finally figured it out today looking at the pics while I was sitting through a deathly boring faculty meeting. Will post updates soon, I hope.

On 9/25/2018 at 10:01 AM, gate said:

1)It is a common practice to make chassis and other decorative elements in one color and the "dangerous" crane structures and outriggers in the other bright colour, so I feel like you should stick to those 2-3 colours max.

2)From the looks of it, if it is longer that would be really swooping into the eyes, but the real cranes seem to have longer boom, roughly for a half-length of the crane itself.

Hope that helps

Thanks, Gate! Yeah, I think there might be too many colours going on now. Tan and red can easily be done away with, but I'll see what the overall package looks like first. As for the boom, I made an extended version of 42009's and the overhang is a bit more pleasing now. I hope to have a rudimental superstructure done soon.

[1gor]

You're welcome @suffocation. I hope for myself that I'll have time for LEGO for weekend or next week due to madness at my work 

At least I have some time to surf through forum. Looking forward to see new images 

[suffocation]

Haven't updated this in ages. Managed to start working on the boom at long last - just a very tentative prototype based on the Grove model published elsewhere on this forum.

[Yevhen]

Your outriggers look enourmosly huge, complicated and weak.

[Bartybum]

Oof those are big outriggers. Can they lift the chassis?

[1gor]

Outriggers are a bit big, but crane is huge (as it should be). Somehow I have feeling that you will need new furniture to store it after build 

Did you consider outriggers like this?

http://www.aquickpickcrane.com/wp-content/uploads/RTs-006.jpg

[suffocation]

6 hours ago, Yevhen said:

Your outriggers look enourmosly huge, complicated and weak.

Said the troll who's never MOCed a pin in a beam.

3 hours ago, Bartybum said:

Oof those are big outriggers. Can they lift the chassis?

The chassis yes, the whole crane no since the end model is likely to weigh in excess of 5 kg. I went for reach over power.

3 hours ago, I_Igor said:

Outriggers are a bit big, but crane is huge (as it should be). Somehow I have feeling that you will need new furniture to store it after build 

Did you consider outriggers like this?

http://www.aquickpickcrane.com/wp-content/uploads/RTs-006.jpg

Ha, I guess I'll be out of money for new furniture by then

Those outriggers are standard fare but it's hard to give them any decent reach without being ridiculously flimsy.