[HELP] Crab Mechanism for Hooklift

[Balrog]

Hi fellow addicts. A word beforehand, if I call the mechanism wrong, please correct me.

I am currently still developing some kind of hooklift container truck as a C-model of 42009. This is more challenging than I thought.

At first I had the idea of building a hooklift mechanism as it is common on trucks. But what I came up with was either too unstable or too bulky. So I was thinking about this a lot, then laid it aside for a while. Now I am back at it and have a new idea. I saw some other container trucks, the work with a simple hoist mechanism, but that seems somewhat inapropriate and I will only consider this as last resort. And then I came up with a idea of some kind of a boom that can extend. My idea was, that the "platform" can extend by half and the "hook" travels the hole length so the tipped platform can take on the containers. Still super complicated and probably impossible with the given parts.

Now I have this boom idea tha is basically a boom like on the crane, but instead of extending, I have a crab going the whole length. Containers will be put off and on through tilting the boom and the traveling crab. I have a prototype, but before continuing, I wanted to ask if someone has a brilliant idea to make the crab more stable or rigid. As it is now, it will probably fail under load.

Here is a picture of the boom center:

The boom itself will be wider later to provide good travel for the container and to secure the crab to the sides.

And here is the prototype crab:

The wheels roll on the side liftarms of the boom. The 32L axle drives the wormgear, which then lets the crab travel via the gear racks of the boom.

I would have shown this combined, but LDD wouldn't let me.

The question is: How can I improve the crab to be more stable?

Also there is a height difference. So if the 32L axle would rest in the black 3L pin with center pinhole, that would be awesome. I know the height difference could be solved by driving a 8T gear through the worm gear which sits on the same axle with a 12T double bevel gear which drives the gear racks. Getting the 32L axle to the same level as the pinholes of the boom would be brilliant.

Also, here is the LDD file!

Thanks in advance for all the help!

[Zerobricks]

I suggest you to spread out the wheels further apart to make it more stable.

[Balrog]

I thought about that, too. But today I had a different idea for the crab. Looks promising for now. Perhaps I need to rework it once more.

Basically the frame of 2x4 bent liftarms lies on the upper side of the rail and the 2x1 liftarm with axlehole provide some stability on the lower side. It is run by a 16T gear. The new red 8T slider gear has no function. It is just there, so the worm gear does not slide back and forth. Here is another view:

Next step is to get this properly driven and the 32L axle attached to the boom.

Here is the .lxf

Suggestions are welcome.