[MOC] ZiS 22M Halftrack

[Milan]

Production of the ZiS-22 lasted from 1938 until 1940 resulting in only 200 samples built of which a small number was used during the Russo-Finish conflict of 1939/40.

(photo from

05m6.de, used with permission)

LEGO Model:

Made on ZiS 5 chassis, all the vital components are the same.

Steering and suspension is the same on front axle.

Drive is different, it has faster output from XL motor, because tracks have internal reduction.

For detailed description of the chassis, suspension, cabin and cargo bed and its components, please see my

ZiS 5 model

Back axle:

Back axle has differential, and reinforces all around.

Turntables are used as a connection points to the trucks for three reasons:

1. To release drive axles of any pressure from weight of the truck

2. To have strong 4-point connection of axle and single caterpillar track

3. To allow caterpillar tracks to have infinite rotation (needed for rolling over obstacles)

This axle is extremely strong with turntables, weak point is differential, which can break the central 12 bevel gear under heavy pressure.

It took me few days for axle to make, test and implement into the chassis.

It can be removed and changed with regular axle for wheels in about 30 seconds.

Caterpillar tracks:

Tracks are made to be as real as possible.

In order to achieve perfect realistic look, they have many parts, and single track weights 370 gr.!

These red covers are, like on real one, protection of chain drive system. Yes, real halftrack has indeed chain drive, which sometimes broke and caused great problems.

Final setup weight about a kilogram:

Cargo bed:

For this version I wanted to make canvas bars, so I did it with axle and connectors and a lots of axle joiners.

The rest of the cargo bed is the same, with small modifications to be able to connect with canvas bars.

Variations:

From variations, I choose to make cargo bed version, and tractor version.

Playability:

Model was tested outdoors and it performed ok, without breaking gears.

The truck weights nearly 3.5 kg,

For best results, it should be kept and used indoors, on flat surface or on carpet. Then it can easily climb over sleepers, carpets or small obstacles.

Instructions:

If there is enough interest, step by step paid instructions will be completed

I am still giving away free .ldr files as a rough sketch.

Video:

(2.5 mins)

http://youtu.be/s6_helFqsNQ

Photos:

Rest of the photos are on my website:

www.ultimate-design.org

[Zerobricks]

Nice use of studded differential casing and a 12 tooth gear! How are chains holding up?

[Doc_Brown]

What an amazing project! looks great. :thumbup:

I'm curious to know too about the chains as well.

[dhc6twinotter]

Awesome project! I like how you built those tracks.

I never realized the halftracks used chains. Pretty interesting!

[Milan]

Chains are actually not a issue, I tested the halftruck by pushing the chair (which I have done numerous time with ZiS 5), and it did push it, but chair had good grip few cm later and central diff's gear cracked. Chains were good. They never snapped, which is surprise for me! Also they endure on the outside play in dirt, while small gear cracked again.

I left chains to be a tiny bit longer than they need to, to be more elastic, maybe that helps.

dhc6twinotter: this truck is a rare exception. Chains are never good with tracks. But I guess designers in 1938 did not have much time to make other solution. BIg boss was inpatient for his new winter vehicle :)

[Blakbird]

You always come up with great models of subjects I've never seen before. Thanks for keeping my life interesting!

[Rishab N]

This entire series of trucks that you've made are all excellent and this complements them well

[Alasdair Ryan]

Very nice truck,its something different which I like.

[jorgeopesi]

Nice black and white pics, the tracks always will be my weakness...

[darsedz]

Nice work, especially track solution...

[Milan]

Thanks all!

Moving on to the construction equipment and rc buggys!