[MOC] Flatbed Tow Truck

[KevinMoo]

Hi, everyone!

It’s been a long time since I posted my last MOC on EB.

Today I’m gonna show you one of the projects I’ve been working on lately: a flatbed tow truck / US style wrecker.

This is the biggest MOC I’ve made so far...And it is packed with loads of features & functions.

Some general specs:

Weight: over 4 KG

Parts used: over 3800 pcs

Dimensions: 760mm (L) x 170mm (W) x 220mm (H)

It features:

- V8 fake engine

- Openable doors

- Working headlights

- Independent suspensions on front axle

- Pendular suspensions with shock absorbers on rear axles

Motorized functions:

There are 8 motorized fuctions in total, powered by 9 PF motors,

remotely controlled by 1 IR Controller + 1 IR Speed Controller (channel switching on both controllers is needed), simple structure with no gear box:

- 2 XL for propulsion

- 1 Servo for steering

- 1 M for opening bonnet

- 1 M for wheel lift lowering & raising

- 1 M for wheel lift reaching out & retracting

- 1 M for bed tilting

- 1 L for bed sliding

- 1 L for winch

A video showing all functions: (Original video on YouTube is 60fps, don’t know why it doesn’t work here)

I managed to hide all motors inside the chassis, including the one that powers the winch. I’ll talk about it later.

Some more video clips: (Again, all 60fps)

This is the propulsion motors assembly.

2 XL hard-coupled with 12-teeth bevel gears, and has a total gear ratio of 25 : 9 before power reaching rear-axle differentials.

That’s enough torque to propel this heavy truck.

Rear axles have pendular suspensions, connected by 3 small turntables. Soft springs are for balancing.

Structure is solid enough to bear the load, but I also designed a similar one with extra support on the middle turntable.

It’s 1 stud longer so I didn’t use it on this already long truck.

This is what the chassis looks like.I was wearing latex gloves for anti-sweating...

Eight 200mm-long PF extension cables were used to connect motors to IR receivers and IR receivers to battery pack. They were well hidden right underneath the battery pack.

Now let’s take a look at the bed.

In the picture above, the arrows indicate how power goes up the bed. Red ones are for bed sliding while green ones are for the winch.

I decided not to put a motor on the bed because it is ugly and too big. A real flatbed’s winch motor is fairly small compared to its size and usually unnoticeable.

As a result, I have to compromise on deck height...

More photos:

At last, I have to say I’m not satisfied with this MOC for several reasons:

Deck height: just too high for a flatbed. As I will not compromise on a visible motor on bed, height increased at least 3 studs.

Loading angle: about 19 degrees, not a good number

Most importantly, too long and too heavy. Front wheels and Servo are working under high pressure, even with 3 hard springs on each side the front part is still overburdened.

Perhaps an extra pair of wheels in the middle would solve the problem, but it will lose its aesthetics and no longer looks like a longnose US truck.

I didn’t want to publish it at the beginning because it’s imperfect, but I spent too much time on it and don’t want to waste it, so finally created this topic and shared it with you.

Again, see my other creations on Rebrickable at:

http://rebrickable.com/designer/musenkevin

And my YouTube Channel:

https://www.youtube.com/c/KevinMoo

Enjoy!

Edited September 19, 2015 by KevinMoo

[LeocornoProductions]

Just phenomenal

[lcvisser]

Great build! I like the overall look of the cabin and truck in total. The pictures look great also, and it's nice to see the "behind the scenes" movies.

I agree that the bed is a bit high. It seems the suspension of the rear axle is in the way of the bed mechanisms. To me it seems really hard to build a truck suspension at this scale using the standard LEGO shock absorbers. 2LegoOrNot2Lego does a great job using the rubber bands though, and his trucks seem to be quite heavy too. Maybe consider such suspensions for future MOCs so you can have more space around the rear axles.

[Kiwi_Builder]

Looks great! I just found it on Youtube then hopped on here and here it is, it works really well Those 'behind the scenes' videos are great, they really help to understand how the truck works. Could you give some more details on the front suspension? Whenever I try to make front suspension in this scale using that technique I always get problems with not having a good turning circle and having the wheels on terrible outwards angles from each other. It would be great if you could share more on that and good job on the MOC.

[Alasdair Ryan]

Nice looking truck,why has Jim not given you a technic badge yet?

[Rishab N]

Nice truck! I think you should be happier with this MOC as there are many good points

[Thirdwigg]

Very cool. I like the winch idea. I love using those long axles with some sliding gears.

[Erik Leppen]

Not satisfied? With this? I think it's brilliant! I wish I could build this good ;)

I'm glad that in the end you decided to post it, because I think it's really great. Yes, I also noticed that the bed was a bit "high", but I think that gives it a really strong look, which I really like. It looks really heavy-duty. I think it's a great combination of function and form.

To give a few feedbacks, there's a few things I noticed:

I think the ground clearance is too small. There are beams below the frame that look really close to the ground. Maybe you could get rid of those. I know everything is filled with functions, but with the 5x7 frames and long beams you can build a pretty strong frame that takes little space.

Another one is the rear wheel covers. I think those are pretty large. The rear wheels don't steer, so you can build the wheel arch close to the wheel. I think this would be more realistic.

Also if the suspension on the front axle is a problem, maybe you could do with a live axle suspension for the front instead.

But of course these are minor issues. I think the truck is pretty much a masterpiece :)

Edit: also, the presentation is also really good.

Edited June 20, 2015 by Erik Leppen

[Edwin Korstanje]

Very great Flatbed truck

[Boulderer]

Great presentation ... thank you for taking the time to put so much detail into your post.

The truck looks great. The bed height may be a little off by comparison with the real world but, Lego components are what they are and you have to work within the limitations that they impose.

As said further up the topic, I wish I could build half as creatively as you are able.

[KevinMoo]

Great build! I like the overall look of the cabin and truck in total. The pictures look great also, and it's nice to see the "behind the scenes" movies.

I agree that the bed is a bit high. It seems the suspension of the rear axle is in the way of the bed mechanisms. To me it seems really hard to build a truck suspension at this scale using the standard LEGO shock absorbers. 2LegoOrNot2Lego does a great job using the rubber bands though, and his trucks seem to be quite heavy too. Maybe consider such suspensions for future MOCs so you can have more space around the rear axles.

You’re right. To let the shock absorbers bear the load alone is a terrible thing, just like the front axle...So I used a pendular suspension, two rear axles can “rotate” independently and let the three turntables share the load. Also two Technic Pinballs are added to each axle to reduce the “rotation” like this:

[KevinMoo]

Looks great! I just found it on Youtube then hopped on here and here it is, it works really well Those 'behind the scenes' videos are great, they really help to understand how the truck works. Could you give some more details on the front suspension? Whenever I try to make front suspension in this scale using that technique I always get problems with not having a good turning circle and having the wheels on terrible outwards angles from each other. It would be great if you could share more on that and good job on the MOC.

It’s a simple combination of a 12-teeth gear & a 7M gear rack. Note that the two thin beams highlighted in the picture is a little bit in the way of the wheel hub's movement, but not a big problem. The real problem is, the truck is too heavy and the Servo didn’t work quite well. Such kind of independent suspension should be used on lighter models, or using more wheels for extra support. I still don’t figure out how to solve this problem on a long-wheelbase model without using more wheels. About a good turning circle: more steered wheels. Both on the front and back. Like set 42009. Outwards angle? How?

Nice looking truck,why has Jim not given you a technic badge yet?

I’m still a newbie to this forum and Technic building. Long way to go.

Think I need more better MOCs to earn one.

[TheItalianBrick]

First: looks very well executed! Be happy and satisfied really!

In my opinion the cabin looks "ugly", I do prefer european trucks, but I'm ok with American style ones if done nicely.

The rear axle has an unusual setup, but nothing wrong with it if you are happy with!!

What I find outstanding is the video quality!! Simply impressive! I would love to be able to do same quality videos!!! As conclusion be proud of this MOC and I really like it a lot!!

[AndyCW]

Wow! The function density is impressive. I have driven vehicles of this size and they are entertaining for a couple of miles and then it quickly becomes tedious.

v/r

Andy

[KevinMoo]

Not satisfied? With this? I think it's brilliant! I wish I could build this good ;)

I'm glad that in the end you decided to post it, because I think it's really great. Yes, I also noticed that the bed was a bit "high", but I think that gives it a really strong look, which I really like. It looks really heavy-duty. I think it's a great combination of function and form.

To give a few feedbacks, there's a few things I noticed:

I think the ground clearance is too small. There are beams below the frame that look really close to the ground. Maybe you could get rid of those. I know everything is filled with functions, but with the 5x7 frames and long beams you can build a pretty strong frame that takes little space.

Another one is the rear wheel covers. I think those are pretty large. The rear wheels don't steer, so you can build the wheel arch close to the wheel. I think this would be more realistic.

Also if the suspension on the front axle is a problem, maybe you could do with a live axle suspension for the front instead.

But of course these are minor issues. I think the truck is pretty much a masterpiece :)

Edit: also, the presentation is also really good.

Good catch on those beams, they are not in my original design. I don’t know if the chassis will break without those beam, it seems fragile down that part even with 5x7 frames. You’re right about the rear wheel covers, I made it large only to create a delusion, which makes you think the truck is not so long and the bed is not too high...

Front suspension is a total failure to me. Those shock absorbers have a travel distance of about 1 stud, and they are fully loaded...Perhaps I won’t try a truck this size and weight any more...

[Lakop]

I would buy this. it looks very clean, I love the functions and you have presented it very very well. In my opinion there are a couple of things could be done differently but that would only make it better.

A great build and I would put it in hof.

H

[sm1995]

First: looks very well executed! Be happy and satisfied really!

In my opinion the cabin looks "ugly", I do prefer european trucks, but I'm ok with American style ones if done nicely.

The rear axle has an unusual setup, but nothing wrong with it if you are happy with!!

What I find outstanding is the video quality!! Simply impressive! I would love to be able to do same quality videos!!! As conclusion be proud of this MOC and I really like it a lot!!

Hmm, I don't think it looks ugly. I mean trucks are supposed to look ugly to a certain extent, and I think he captured the look rather perfectly.

So far, this is one of my favorite MOCs this year. Superb work OP

[TheItalianBrick]

Hmm, I don't think it looks ugly. I mean trucks are supposed to look ugly to a certain extent, and I think he captured the look rather perfectly.

He definitely captured it perfectly.....unfortunately they look ugly in reality!! But hey, just my opinion! The rest of the truck it's amazing!

[MaxSupercars]

I like it... Very good MOC... Great functions, great movable flatbed... I have no problem that flatbed is higher... as mentioned it looks more heavy duty... :)

I like the whole gearing inside etc...

Outstanding MOC... :)

Max...

[TheNextLegoDesinger]

AAAAAAAHHHhhhh to beautiful

great moc. i can see your unsatisfaction of the deck.

[Kiwi_Builder]

Outwards angle? How?

Here's what I get every time I try to build independent suspension on the front:

I'm pretty sure that it's something to do with where I attached the 6L ball arms to the steering rack but as of yet I haven't solved the problem.

[jono rocky]

One word 'awesome'. :thumbup:

[trekman]

Despite what you think are flaws, that is a nice truck. I do understand that in Lego you are working with bulky items which are out of scale compared to what is used on actual machines. Nevertheless, I am glad that you posted it. Well done.

[KirTech LAB]

Nice truck!

[Sariel]

Excellent photos, video, and one of the best studless cabins I've ever seen. The wheels look a tad small at first glance, though.