[TC22] City crane

[Erik Leppen]

It's been a while since I actually built some stuff. But I'm back with a new work in progress, for the new competition. The theme is, build a small-scale (maximum 10000 cubic studs) construction vehicle. My choice of subject is a city crane, or compact crane. A mobile crane where the main cabin is on the superstructure.

I won't base my model off a particular existing model, I just want to build a fun mobile crane. As far as I know, no 3-axle mobile crane has outriggers between the axles, but mine has, inspired by 8460.

Functions so far:

• steering on axles 1 and 3. I used virtual pivot steering in he hope the model can be more compact, but the turning radius isn't very tight.
• outriggers (all linked). The outriggers work very similar to those in 8460, but I managed to link the left and right pair

The turntable is not linked to any knob right now. I don't think there's room for that.

I'm not settled yet on the color scheme. Right now I used dark azure with white, with some dark-gray and black as support colors, but I might switch to something totally different. I already tried medium blue with yellow, but I just don't have enough medium blue parts, especially small parts. But I might switch to a whole other color scheme. As with all my models, I use red/yellow axles for functional axles.

Right now it's 15 studs wide and I think I should be able to stay within that. Current length is 33 studs and height is about 9 studs. If I can stay within 17 height and 39 length, that would be 15 x 17 x 39 = 9945, just within the limit. Will be a challenge.

Next main challenge will be to connect a boom. Ill probably use a LA for raising that, and I hope to add the usual 4 crane functions (slewing, raising, extension and string). I probably won't do any functions beyond that.

[m00se]

Looks interesting. Good luck keeping within the 10000 cubic studs.

[Erik Leppen]

First experiment with the boom.

The whole superstructure is crude, just to see if I can get things to fit.

The boom is 4 studs wide, which I think is reasonably to scale. 5 is too much, 3 is too little, also, 3 doesn't allow space for an inner section. But it does mean the boom is not centered, because the cabin is 5 wide and the whole crane is 13 wide, so 5 + 4 + 4. But I don't mind that.

A side view:

The red things below are just there to keep track of the height (17 studs).

I have decided I want to rework the chassis to lower the outriggers by one stud. That should be possible. Then, the're less in the way of the superstructure, and they will actually lift the vehicle (which right now they don't).

As a final little test, toying around with cabin shape (don't mind the blue and red bits, these are temporary):

If I do this cabin shape, the color scheme will have to change though, because I don't have many colors where I hvae the required parts. Basically, only black and white, and I don't like to use black too much. So I probably switch to white for the cabin, but I don't want an all-white crane, so I think I pick another color for the boom and outriggers. Not sure yet, I only have 3x11 panels in a few colors.

[GerritvdG]

Thanks for the update, looks very promising. I follow this one with interest because 8460 was one of the two sets I get for my birthday in my childhood and I really like the subject. 

[Thirdwigg]

Thanks for the update, as this is a fun project.

I respect anyone who can build a module in an 4 wide space. And I really love anything with a worm gear mechanism, so that boom is going to great from my perspective.

I really like the While, Red, and Dark Azure, so I would keep the Cabin white, and see if you can accent with a little red or DA depending on what you have. Shaping is great.

There has to be a better way to do the steering axles though, right? I just can't get past the Golden Ring parts.

[2GodBDGlory]

Good job so far! It's interesting seeing your build process in action.

52 minutes ago, Thirdwigg said:

There has to be a better way to do the steering axles though, right? I just can't get past the Golden Ring parts.

I think this part would work pretty well here; have you considered it?

 

One of these could be helpful under it:

[Erik Leppen]

Sorry for not replying more often and showing progress more often, but I had both other obligations, and other interests. But I finished the model - I believe I'm still on time for the contest.

I changed the color scheme from red to yellow to avoid copying sets like 42077, I think this color scheme is used less, so I think it's more interesting. Also, I had exactly enough 3x11 panels in yellow to do the boom in that color.

I think I have a pretty nice list of functions for a model this size:

• steering on axles 1 and 3
• outriggers (all linked) from knobs on the side of the carrier
• slewing, manual (no knob)
• raising boom with long LA, from knob on the bottom rear of the superstructure
• extending boom, from knob on the top rear of the superstructure
• string reel, from knob on the top of the superstructure
• manually attached jib

I'm particularly happy with the counterweight section of the superstructure, because that section packs 3 function gear trains, and 2 of them are geared up to make them less of a pain to use manually (i.e. make them work faster). Actually, there is a 24:8 gear pair at the bottom of the superstructure to gear up the winch operation while using a worm, so I didn't need a ratchet (that would have increased the height probably).

I had to make a few adjustments to make it fit the box. The vehicle is 13 wide, but those 2 knobs on the sides made the whole thing 15 wide, which wasted a lot of box volume. With 17 height and 41 length, this didn't fit. So I had to change the innards of the carrier to make the knobs 14 wide. But now the gears rub against the panels, so maybe it's actually 14.1. But I consider that 14. The height is 17, also because I lowered the knob on top to sit flush with the roof of the cabin. With those measurements, the available length would have been 42 (42 x 14 x 17 = 9996) which could have been the nearest to the 10`000 limit of maybe all entries :) But alas, the total crane is only 41 long, meaning 41 x 14 x 17 = 9758. Still nice.

Also, I added a jib :D

Now, the rules state, no taking stuff off to stay within the box, but the jib can be attached using a brown #5 axle, but this isn't needed to stay in the box, so I consider that legal. And it's an extra function, which increases the range considerably :)

Here's how the jib works. It is attached to the main boom using the brown #5 axle with the white 2L beam. If you remove that, and put it at the end where the 3x7 bent liftarm sits betewen the blue connectors, then it can be rotated 180 degrees (and then locked with the 2L beam on the brown axle) and the string can be reeled over the pulley at the end.

Finally, box proof:

I will write up the entry post this evening. :)

 

 

 

Edited May 30, 2022 by Erik Leppen

[1980SomethingSpaceGuy]

Hi Erik!
Excuse the curiosity; what is that shiny brass piece on top of the boom's work gear? I think I've never seen this one..

[Thirdwigg]

Should be this. I think.

[1980SomethingSpaceGuy]

My precious! 

Thank you very much!