A Czech truck built by a French guy... Praga V3S

[hanjin-san]

Hello multi axle truck lovers

I'm glad to introduce you my current project, which is already well underway.
It's a 6x6 Czech truck named the "V3S" from the Praga brand (for those who don't know it), who participated to the Czech championship trial truck.
Here are 2 pics of the real one:





Scale is 1/8, AR60 axles with leaf springs, Traxxas Summit gearbox, Hollow point tires and stamped wheels by RC4WD, Hitec 7950TH servo, 750kv outrunner motor from Hobbyking, 3S battery...
All the rest is made by myself; aluminum frame with stainless brazed crossmembers, motor mount, transfer case with 3 outputs, all the suspension components (including leaf springs), tubular parts...

First of all, for a big project like this, the design, done with Solidworks:





To be continued...

[scale4x4]

Watching! If it's 1/2 as good as your truggy this will be one to look out for!

[rockhugger]

I was wondering when someone was going to do an AR-60 6x6 or 8x8.
how are you doing your middle axle?

subscribed

[hanjin-san]

Hello,

The middle axle is like the real one, the drive shaft for the rear axle, pass over the middle axle, guided by a bearing

So, after a little presentation, it's time to show you what has already been done.
I started machining the first pieces in July 2012:

Front leaf spring mount:



In place on the axle housing:



Some châssis parts (rear links, links and leaf spring mounts, gearbox mount, transfer case spacer and driveshaft bearing shaft):



Transfer case machining, with Tekno RC mod 1 steel gears in it:





Motor and spur gear mount:



On the Summit gearbox (with Traxxas gears):





Shift linkage:



Another parts batch (steering servo spacers and bracket, gearbox and bumper nuts, front leaf spring mount):



The stainless steel crossmembers:



Frame rails (approx. 29" long) made with 1" square aluminum tubing cut in half:



And all these parts assembled together:















Next to my Comanche:

[rockhugger]

Beautiful work. Great planning and execution.

Hey everybody, did you see this!?!?

[HDMM]

This is nuts! I need a cnc mill!!!

[Dostradamas]

Damn skippy!

You want an apprentice in your shop?
Passport ready............................................. ...................

Nice work, nice project idea.
Subscribed.

[greenjk]

Beautiful work, I look forward to watching the progress on this.

[hanjin-san]

Many thanks guys !

Originally Posted by HDMM

I need a cnc mill!!!

Me too... All those parts are done on a column drill with cross table... No cnc here...

Originally Posted by Dostradamas

You want an apprentice in your shop?
Passport ready............................................. ...................

I need to ask question to my boss

Well, as I told to rockhugger, the drive shaft for the rear axle pass over the middle one.

Here is a pic of the 1/1 rig (the long and thin shaft in the middle is for rear winch):



As I cannot modify the AR60 housings like the SCX10 axles to get two outputs, I designed a piece, drilled to install two ball bearing for a shaft.
In addition, this part is also a bracket for the top suspension link.
The result after some cad work:



The right piece is for the rear axle, just to mount the link.

A view of the setup:



Let's start the milling process, step by step

I decided to use an "Alplan" aluminum block who have the right and precise thickness for the parts:



Face milling with an over-lenght, to grab it in a vice:



Roughing 11mm holes:



Slope milling:



The excess material is cut with a band saw and milled for a clean finish:



Drilling a few holes:



Another slopes milled:



Bottom shoulders:



Another milling step:



The bottom recess, which fits on the housing:



Ball bearing bore (I use flanged bearing):



Cutting of the parts:



And the last step, the finish (chamfers, radius...):







And the fitting test:





Hope you like it
Thanks for watching

[rockhugger]

I don't have the capabilities just yet, but I've contemplated a pass through diff cover for the AR-60 to add a pinion gear and allow you to pass through to the other axle.

Maybe 3-D print, or machining at some point.




Thanks for the step by step. Parts look fantastic !!!

[hanjin-san]

Thanks

Yes, create a new diff cover can be another solution.
On the other side, using the stock small 2mm cover screws to secure it to the housing can cause some durability issues... Or perhaps by using the bearing mounts screws
In my case, I wanted something that was like the real setup and also something easy to make.
So I choose this method and it works great

[scale4x4]

Beautiful work!

[BigSki]

Nicely fabricated parts! By doing the modeling in CAD, you solved all of the design issues before machining any raw material.

I'm guessing that the rear axle is being run in the opposite offset compared to the middle axle to make room for the 2nd drive shaft?

[hanjin-san]

Thanks

Originally Posted by BigSki

I'm guessing that the rear axle is being run in the opposite offset compared to the middle axle to make room for the 2nd drive shaft?

Exactly !
The switchable diff on these AR60 axles is great for that !

The next stage was the making of the rear leaf springs.
After some hesitations for the choice of the material, I finally decided to use a stainless steel ruler.
The elasticity seems to be good and this material is soft enough to be easily cut and formed.
So, after a few hours of work, here is the result:



Assembled on the swivel:



On the axles, the guides:



All the parts mounted on the frame:





I had some length issues with the drive shafts between the transfer case and the middle axle at full suspension travel, one was too short and the other one too long...
For the longest one, no problem, just need to shorten it.
However, I couldn't extend the shortest one so I decided to extend the transfer case output shaft.
I've also made a extension with a ball bearing to reduce the stress on the shaft:





The final drive shaft setup:







Some flex shot:

[hanjin-san]

For the steering, I use VP knuckles and c-hubs with homemade arms.
The long steering link is mounted behind the axle:





The steering angle:



For the front leafs, I used the same material.
I made 2 tools for shapping the eyelets.
The first one, a steel plate who has the same thick as the inner diameter of the eyelets with a rounded end:



I've clamped the leaf spring on it and gently bended it to approx 180°:



Now finishing the bend with the second tool who has the same shape as the final eyelet, with a mobile part like a vice:



Compressed:



The final result:





On the axle:

[Nova's Ark]

Amazing! Such craftsmanship and attention to detail. Subscribed for sure. Thank you for posting.

[Dostradamas]

Keep it coming.

I feel this thread is already sticky worthy in the multiple axle section.

[scale4x4]

Incredible work! I can't wait to see what you come up with for the cab.

[JLF]

Amazing design and skills! Great thread!

[Robs07junk]

Sir , I Am In Awe Over Your Detail In Craftmanship !