INFORMATION REQUEST:

Anyone have technical information on the MA3-543 sometimes identified as either the MA3-7410 or MA3-7430 semi tractor?

I am particularly interested in the rear frame and suspension construction.

I know I have asked this same question before and I apologize but perhaps someone has turned up something new in the past few years???

The overall frame length is shorter on the 7410 semi tractor than that of the Scud Missile Carrier. Also the rear axles (#3 and #4) are more closely coupled and the suspension is handled by massive leaf springs and some sort of "boomerang" shaped lower support arm.

As you can see the rear suspension is uniquely different from the torsion bar suspension used on the rear two axles of the Scud TEL.



Torsion bar suspension is generally used on vehicles where the total vehicle design weight is known within reasonable limits. The torsion bars can then be sized appropriately to handle the given vehicle load weight. (The weight of a Scud missile plus the carrier vehicle weight is always a known value. It is always the same.*)

In the case of a semi tractor only the maximum allowable load weight can be known by the designer. In the case of military vehicles even in this the designer can routinely expect that the vehicle will be over-loaded beyond his calculated maximum. Hence the use of leaf springs rather than any other form of suspension.

On the 7410 you will note that even these large springs also carry an overload or booster spring below the main spring.


*The only time the missile weight changes is after it is fueled which does not happen until the missile is in the vertical position and standing on the hydraulic legs of the launch stand.

Oh, I know, I am going to like this build.

Yeah, all I gotta do is pick up the new Scud missile carrier, throw out everything that has to do with the missile and start chopping up the frame!

I would however like just a little more info on that rear end before I make my first cut.

Oh, and I will also need the fifth wheel assembly and the winch off the MA3-537 tractor but hey, it is only money and more parts for the spares box, right?

It also came in a five passenger cab version, with or without the winch.

Think of building this rig!


Or this one!!!!!

By the way that is an electrical generator on the back of the tractor for this application and when in traveling mode I am fairly sure those rear tires on the trailer are electrically powered. I believe those are planetary gear head hubs on the trailer wheels and the Russians have done this before, many times on large ICBM missile transport trailers!

Seems like a lot of my questions were answered back in December by Marco Folin and Eduard Sorokin on another similar post and I missed it!

Check it out:

https://armorama.kitmaker.net/forums/229751

Almost every answer I could hope for as posted elsewhere on Armorama by Marco Folin; Call Sign: lagu and Eduard Sorokin; Call Sign: EdCraft.

WOW!

Thanks guys!



Tech Manual Drawing?

Hallo , Michael .
It is links to catalogue parts .
On every unit to drawing and name detail .

Maybe come in handy .

http://www.autopiter.ru/russiancatalog/maz/maz-543--7310- .

http://zapchasti-mayak.ru/maz/543 .

http://www.autosnabrf.ru/acat/2/MAZ/MAZ-543-7310 .


....

Fantastic stuff there Galkin.

Hate to ask for more but do you have anything on the 7410 which is a bit different?
Maybe just a side view of the shortened frame?

Thanks for your contribution.

Mike

Still one of my projects..i have to find the courage to start it..not to mention the fear of Murphy's law!!!(maybe one day Trumpeter or Meng will do this truck??)..already sorted some maz 537 parts plus some resin wheels (DEF).
MArco

Hi Michael - certainly an interesting thread. While I'm not all that familiar with the tractor being discussed, I do have a general interest in suspension systems.

I can generally grasp how the top loaded leaf springs, mounted above what looks like a curved walking beam...(?) works; that is, I suppose, self leveling axles with the leaf pack above ?

However, I haven't a clue how the stacked "A" arms also shown in the diagram (which also appear to have torsion bars?) work? Not on their own, I understand torsion bar suspension, but what I can't figure out is where/how they work in conjunction with the primary leaf spring suspension?? Hmmm? So, I guess I too want to see some clear photos of what's going on back there.

Looking forward (hopefully!) to learning more about this setup.

Cheers
Nick

Nick, it sounds like you and I have similar interests:

I think/guess that the A arms are left over from the suspension of the standard longer MA3-543 chassis but are now used without the torsion bars. I suspect those are just short hinge pins we see anchoring the A arms to the frame on the semi tractor.

The A arms continue to give the wheel hubs the controlled vertical motion they have always had but now the curved walking beam serves as an equalizer between the #3 and #4 axles and the leaf springs serve as the suspension.

It is interesting to me that on the older MA3-534 the walking beam equalizer is pivoted in the middle and provides a rock solid arm that gives very definite equalization between axle 3 and 4. One wheel goes up the other will be going down without any doubt.

But on this later design the curved walking beam is not pivoted but floats. Also the walking beam does not connect directly to the frame. It only connects THROUGH the flexible spring which itself carries the frame mounted pivot. I suspect this arrangement would give a much smoother and controlled ride than the earlier designs.

My one question at this point: Do they perhaps still also use the torsion bars? The T bars would carry a part of the weight of the trailer load and would perhaps also act a bit like shock absorbers to dampen the vertical movement and keep the rear wheels in contact with the ground?

But this is all conjecture at this point until, as you say we get a better photo/drawing of this very interesting rig.

Something interesting from the other end of the MA3 chassis: the steering gear arrangement.
My thanks to Galkin Axeley and Autopiter.ru


Drawing for discussion purposes ONLY

Just came across another view you may not know already



Full size

H.P.

Had the particular vehicle but not from this extreme rear angle.

Thanks as always.

Mike

Slightly enhanced enlargement:



Still no answer to the torsion bar question but my guess is no to the T bars given the size of those monster leaf springs!

This photo does answer one question though, just how the sub-frame for the fifth wheel structure mounts to the main frame. Progress!

I know exactly what you mean Marco. I scratch built a Bussing-Nag truck using a 30 year old vac-formed cab and then they come out with it in 1/35th. Likewise on building an old vac-formed kit of the Blitz bus and now there is a plastic one in 1/35th on the market.

It is just the chance we take.

I'm no stranger to scratch building large custom leaf springs (in plastic that is). I am sort of looking forward, with special interest to this part of the MA3 tractor project!

Michael - first, your scratch built leaf spring assemblies look great! down right impressive, considering what a pain in the neck it no doubt was to get the various segments measured, packed, and then aligned - nice.

Second, in looking at the close up photo above, which appears to prove your guestimate regarding the "A" arms to be more or less correct (or at least reasonable) - the picture also seems to suggest that the rear suspension is independent? - as I noted, I'm not an expert on this truck - If so, this is an:

independent suspension dampened by a centrally pivoting leaf spring-walking beam flexible truss, with horizontal control via A-arms....yep, pretty typical....haha!

Who knows - maybe more pictures will show up - I did a quick search on the Chinese version, the Manshan MS2400 for more images - but, not luck

Cheers
Nick

Did you notice this forthcoming one ?



H.P.

I did notice it but alas, that small scale (1/72th) just won't fit in with all my other big boys on the shelf!

Even as a small child I hated the simple plastic trucks, planes and soldiers that seemed to come in all different scales. Back then I already wanted everything to coordinate so now it is 1/35th or nothing!

ModelCollect also offers the 7410 tractor with the huge "Big Bird" Air Search Radar trailer! That is just what I am looking for but again it is 1/72nd scale - I just can't do it.

I would willingly give up 4 1/2 feet of prime model display shelf space for that unit in 1/35th!!!

Hey Nick, go back up about fifteen posts ago. Check out the wheelbase dimension drawing for the 7410 tractor.

I know this still does not constitute real proof but whoever made that drawing included the torsion bars and T bar anchors on the #1 and #2 axles but show no such structures on the #3 and #4 axles!