Tommy Styrvoky

[MOC] M4 Sherman Crab tank (RC)

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19310300574_c183ed1a83_b.jpgLego M4 Sherman Crab (RC) by Tommy Styrvoky, on Flickr

Finally after 2 months of work, I present my latest model, a 1/18th replica of a M4 Sherman with a mine clearing flail. This model is one of my most complex models I have built. It houses 7 Power functions motors (2XL, 2L, 2M, 1 servo), 3 IR receivers, and a 8878 rechargeable battery.

Photo of real vehicle with flail in operation


Design of model

This vehicle has been a dream of mine to replicate a M4 Sherman ever since I began building tanks. There was a lot of planning over the past year to the design of this, there are different components from other tanks of mine that I combined to build a ultimate version of a Sherman. There is little space left inside, as the transmission, electronic clutch braking mechanism, and flail components take up all of the lower hull space, there was little space for the turret's mechanisms to be routed into it. The gun's elevation is controlled by a mini linear actuator that is located below the turntable and rests on top of the mechanism that shifts the gears for the transmission, and elevates/depresses the flail.

The first Sherman I built was my 3rd tank of a larger scale, it was designed to replicate a British version of the Sherman, the Sherman Firefly. It was flawed in several locations, but I wasn't pleased with certain components of it, the suspension was inaccurate for the early version of the Sherman, as it uses VVSS(vertical volute spring suspension). My model had HVSS (horizontal volute spring suspension), this version of suspension is only used on later variants of the M4A3E8 Sherman(vehicle used in Fury). I attempted to build another version of a Sherman in the fall of last year, but it suffered from the same issue, the suspension was incorrect in size, I decided to scrap the project and build other vehicles instead until I found a better, more accurate solution. I decided to use the Torsion bars from the Hetzer, as it would provide the proper angle for the suspension swing arms, and be low profile, so the hull could mount the Transmission from my Tiger I.

The transmission takes up nearly the entire 3/4 of the lower hull of the vehicle, it fits between 10 studs of free space, and has 2 gear ratios, a 1:2084, and a 1:1.3474. The remaining space of the lower hull is taken up by the electronic clutch braking mechanism (this creates the effect of the real steering mechanism of the M4 Sherman, to steer one track's power is diverted to the other track, and the unpowered track is braked). The space behind that is for the 8878 rechargeable battery.

Another complex component for the Sherman is the turret and the transmission housing cover, these pieces have a complex shape to them, and are both round. The transmission housing cover is situated at the front of the vehicle, where the final drives interface with the transmission. It took 5 revisions of it to cover the knob gears behind it, and retain the proper shape. The turret was difficult too, but I broke it up into 4 different shapes that could be replicated in bricks and be combined to produce the proper round shape. Those components being the sides, top, mantlet, and rear bustle. The sides and bustle were the most difficult to replicate, as the bustle has a complex protrusion off of the back of the turret that is used to house the radio. The sides were difficult as they had to slope upwards to to roof of the turret.

Sherman Firefly from over 2 years ago


The current model isn't entirely perfect, the major imperfections being the height of the center portion of the hull, and turret size. The hull is 2 studs too tall, as it needs to mount the flail's L motor for power, and the main axle that powers the flail's Linear actuators has to have a directional change. The turret is slightly too tall, but this was to compensate for the height of the hull, it looked too small, and the mini linear actuator made it taller. If a standard version of a M4 Sherman would be built, it wouldn't have these issues, because of the internals, though I am pleased with how it looks, it could still be improved.


The Sherman crab was designed to clear minefields the Allies would encounter during the Normandy landings, there are several other Flail vehicles used too, but I chose the Sherman variant.I will spare the remaining bits, as this post is getting long, more information here if anyone is interested in the history of it. http://www.dday-over...g/crab_tank.htm


19906663476_594c6434e4_b.jpgLego M4 Sherman Crab (RC) by Tommy Styrvoky, on Flickr















As some may know I will have college coming this fall, so this will be my last MOC for a long time, I am uncertain if I will have time to build something large over any breaks, though there is LDD and Ldraw , it isn't the same as working with real bricks. I do have big plans for next summer, as I suspect that will be the next time I can work on a model.... 1/15 MAUS... but more information on that come in a couple weeks.

Edited by Tommy Styrvoky

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Tommy great work! It looks very real. Sometimes I had to look at photos longer to know if it is model or real tank. It must be enough hard to build in all the motors and gearing and to make the the tank visual real... Thanx for sharing... :)

Very nice photos and details... :)


Edited by MaxSupercars

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I think you absolutely nailed the proportions of the Sherman. Excelent model!

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To non-tank-experts like me, this looks fantastic despite the shortcomings you listed. Enjoy college and don't worry if your Lego break lasts longer than two semesters - you'll be back sooner or later.

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Truly great way to make a memorable creation before long pause on college! :) Everything is nearly perfect, I just saw one side of the chain mechanism-arm has lost its connection, on the video. One side has support that prevent this, but this side has driven axle that powers the chains, so I guess its the reason why it could not be reinforced better.

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Excellent MOC! I like the second render of the drive train and the use of knob wheels. Nice work!

I have a second render is coming, I exported the .3DS file from Ldview, so I am am making a higher quality render of 1000 samples in Blender, the only problem is the Ldraw parts are low polly, and I am unable to smooth the textures for some odd reason.

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I love it, the flail performs great and the whole tank looks great. You really mastered tank building...

No landmines in your garden ha? The ninja cat scene is hilarious :-)

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It has been awhile since I have been at home, and I had a break over the past 4 days. I got around to disassembling the M4 Sherman crab, and building another MOC. Here's the transmission from it.

22345876939_14b535b39a_c.jpgLego M4 Sherman Crab transmission by Tommy Styrvoky, on Flickr

22345877779_dd06461173_c.jpgLego M4 Sherman Crab transmission by Tommy Styrvoky, on Flickr

22344999378_691f71dd19_c.jpgLego M4 Sherman Crab transmission by Tommy Styrvoky, on Flickr

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