I've seen reference of Gaz MMs mounting 20mm Flak guns. Would a 3.7 cm gun be an option? Size looks O.K. but I question weight and ability of the chassis to stand up to the recoil abuse. Any thoughts?

GAZ-MM has a cargo capacity of 1360 kg (3000 lbs). This was a lighter, less robust version of the Ford Model-AA chassis for lighter duty work.

By comparison:

GAZ-AA had a cargo capacity of 1500kg (3307 lbs). This was based on the heavier duty Ford Model-AA chassis.

Gaz-AAA had a second rear axle that boosted cargo capacity to 2000 kg (4000 lbs).

Now...

Combat weight of the 2cm Flak 38 was 420kg (926 lbs).

Combat weight of the 3.7cm Flak 36/37 was 1550 kg (3420 lbs).

Combat weight of the 3.7mm Flak 43 was 1250 kg (2760 lbs).

The 3.7cm Flak was usually mounted on a Sd.Kfz. chassis (4536 kg (10,000 lb) or 7258 kg (16,000 lb) capacity), or a panzer chassis, because with crew and ammo, things get heavy. And as you get close to maximum load capacity, the vehicle strains more and is less mobile, especially cross-country.

Now, as a matter of practice I would say the 3.7cm Flak would NOT have been mounted on a GAZ truck.

As a matter of expedience (desperation) there are two rules: 1. long-term wear and tear does not matter. You need a job done and you need it done now. It can work short term. 2. Cargo capacity is the maximum weight the chassis can take without LONG TERM damage. You CAN overload a chassis for as long as it will last, but you will drastically reduce its lifetime as you increase load over capacity, at roughly a exponential rate, until it breaks.

The above should help explain why the 2cm Flak was so much more versatile and used on so many more chassis than the 3.7cm. Could you put a 3.7mm on a GAZ? Sure. It was just not preferred.

1360 kg ? Where did You find this nonsense ?

Both GAZ-AA and GAZ-MM had same predecessor - Ford AA truck, without any division on "heavier" and "lighter" versions, because the USSR bought only one type of Ford chassis for license production.
GAZ-MM is SIMPLIFIED GAZ-AA truck due to Wartime production limitations. Yes, it has some simplifications compared with GAZ-AA (including its general appearance). But almost all mechanical design: chassis, engine - all running gear - remains unchanged.

Thus, the load-carrying capacity of GAZ-MM is absolutely same like the GAZ-AA - 1500 kg. And any other variations are absent here.

Only in one case the load-carrying capacity of GAZ-MM could be reduced - if some particular vehicle has single rear wheels (instead of dual rear wheels on "normal" production trucks). Such measure was made by automobile plants during most difficult period of War - in 1942 - 1943 - due to lack of rubber and steel in sufficient amounts. And sometimes such measure was adopted in Army field repair workshops due to lack of spare parts and tyres.

And Timothy in his post means not German FLAK guns, but Russian AA guns obviously. He mistakenly means not 20-mm, but 25-mm 72-K Russian AA gun.
Yes, such guns had the weight of 1200 kg and were carried by GAZ-MM trucks.

37-mm 61-K Russian AA gun has the weight of 2100 kg (with own 4-wheel base), and, of course, was too heavy for GAZ 4x2 chassis (even with those gun base wheels removed). Those 37-mm gun mounts were tested on heavier trucks, like ZiS-32 truck (the 4x4 version of 4x2 ZiS-5 3ton truck. Such AA truck was tested in 1941 before the War) and ZiS-42 truck (half-tracked version of ZiS-5 3ton truck. Such AA truck was tested in December 1942). But those vehicles were not adopted for the mass production.

Thus, GAZ-MM is suitable for 25-mm AA gun - but not for larger guns anyway.

No. I meant captured German flak pieces mounted on SOVIET trucks. I do know the difference between German and Soviet AA guns. Jacques, thanks . You confirmed my suspicions. Guess I'll have to settle for a Flak 38. (Would the Soviets bothered with captured Breda 35s? Italian forces were at Stalingrad but there'd be a lot fewer guns and harder to get ammo) Anybody make a 1/35 72-K? (thought about the quad Maxim but is not economically feasible. )

Eduard, you are correct. Sort of. There is a translation error somewhere. US manufactured Ford-AA trucks are listed as having a capacity of 1.5 tons. 1.5 tons = 3000 lb = 1360 kg. (http://aafords.com/aa-chassis/) Russian sources state that the GAZ-AA based on the Ford-AA have a capacity of 1500 kg. 1500 kg = 3307 lb = 1.65 tons. I cross-checked the GAZ-AA and -MM with the Tankograd book "Soviet Trucks of WWII".

This is a discrepancy that I cannot resolve.

I do not know my Soviet WWII trucks well, so I assumed the wartime GAZ-MM, which had a known reduced complexity of manufacture, must also have had a reduced load capacity to account for the disparate information.

Ford did not make a specific heavier duty frame for heavier capacity, that came from the second rear axle and would equate to the GAZ-AAA. Several secondary companies in the USA modified standard Ford-AA frames to increase capacity for specialized duty. This also threw me off when trying to understand the production lineage of the GAZ-AA and GAZ-MM.

My point still stands though.

When would the German's have used a GAZ-AA for the 3.7cm gun...when they were desperate. The GAZ-AA could have barely handled the 36/37 on good, dry roads - somewhat better for the 43.

Hope that helps more.

As for AA and MM, I know the MM did not have front brakes. Perhaps weight reduction was not an issue of frame but an issue of stopping somewhere before the English Channel.

Do keep in mind that weight limitations of trucks (aka 2 1/2 ton truck) is the rating for off road use. If they are used on roads, they can safely handle a heavier load a 2 1/2 ton truck and handle closer to 5 tons, a 5 ton truck and handle 7 tons...etc.

Scott - understood. I didn't want to confuse the issue because so much of the Eastern Front is basically off-road.

Even so, the Germans put the 3.7cm Flak on some heavy duty chassis for a reason...

And I still cannot resolve the 1500 kg and 1.5 ton rating, though the -MM not having front brakes is a very good point I had not considered.

Jacques ! Thank You for Your reply.

Those different weight measures are not the translation errors, but are the results of incorrect conversion of pounds to kilograms.

The matter is that You in the USA use so-called "short tons" (we call them as "American tons" here in Russia), which is equal to 2000 pounds exactly - see the description here https://en.wikipedia.org/wiki/Short_ton.

Thus, 1,5 US tons = 1,5 x 2000 = 3000 pounds. Each pound is equal to 0,454 kg approximately (http://www.rapidtables.com/convert/weight/pound-to-kg.htm), and we have here:

3000 x 0,454 = 1360,777 kg (You can check this result, using the "Lb - Kg" converter on the link above).

We in Russia use the metric tonnes (note the different spelling of the US "ton" and Russian "tonne" words, and their different meaning - https://en.wikipedia.org/wiki/Tonne).

One metric tonne is equal to 1000 kg. Thus: 1000 x 1,5 = 1500 kg.

Each kilogram is equal to 2,20462 pounds exactly, and one metric tonne is equal not to 2000 pounds, but to 2204,62 pounds exactly.

And so, we have here:

1500 x 2,20462 = 3306,93 pounds, or 1,653465 short tons,
because of the metric tonne is heavier than US short ton on about 10 percent.

So, nominally the US "1,5 ton" vehicles have smaller load capacity, than some European and all Russian "1,5 tonne" trucks.

Eduard,

Nice work. But if the load capacity of the frame is based on US calculations where the English system is used, a rating of 1.5T is still 2000 lbs is still 1360 kg.

So if the GAZ-AA is then built exactly the same in the Soviet Union it should have the same load rating as in the USA of 1360 kg, regardless of it being listed in the USA as 1.5T (short tonnes). One kg is still = to 1 kg in the USA or in the Soviet Union and the weight system it was designed with in the USA rated the capacity as (converted) at 1360 kg.

So that means that the GAZ-AA was listed OVER capacity in kg probably because of a conversion of weight error, with the person rating the load using metric tonnes instead of short tonnes to get the kg rating. Or else they liked round numbers and 1500 kg was convenient.

It probably amounts to nothing because, like Scott said, the capacities are listed for cross country capability. But it might explain if Soviet built GAZ-AA or -MM trucks did not last as long as US made Ford trucks simply because of the erroneous extra load rating putting more stress on the vehicle over time than was designed for.

Just to weigh in and such on this:

Let's recall that the Ford AA was a US civilian-market general-purpose truck built between 1927 and 1932. It was rated by Ford to be a 1.5 US ton (3000 lbs) road-based general purpose cargo carrier. Mechanically, it was a slightly "beefed-up" Ford Model A with reduced gearing and a heavier frame and cargo body, and a heavier rear differential with dual wheels. It was not built for nor intended for off-road use, nor as a military tactical cross-country cargo-carrier. Ford sold the USSR license to build the AA.

Russian GAZ AA are license-built copies, in all particulars, of the Ford 1927 AA. As such, having the same engine, tranny, differential, and frame as the US original, they would, in truth, have been rated as "1.5 ton US capacity on open roads". The GAZ MM is the same frame and other stuff as the GAZ AA, but has a different engine - so is labeled as the MM. Both AA and MM trucks were simplified from 1940 for wartime production - including body simplifications, simpler sheet metal, and deletion of the front brakes. The GAZ AA / MM trucks were no more suitable for off-road work than were the original Ford AA versions. IF the Soviets designated the GAZ AA / MM as "1.5 ton" or "1.5 tonne" (designating the metric ton), they were simply "parroting" the original design capacity specs provided GAZ by Ford in 1928. As others have noted, a metric ton ("tonne") is 1000 kg or about 2200 US pounds. As GAZ did NOT change the framework nor the automotive bits - nor the suspension components, designating the GAZ AA as a "1.5 tonne" truck is, to say the least, somewhat facetious. But we all know that cargo capacity designation is approximate and nobody would expect the Sov's to have called this thing "honestly" a "1.3 tonne" truck or something, right?

And NO-ONE should begin to confuse the Ford or GAZ AA trucks with things like the fabulous "deuce-and-a-half" 6x6 trucks of US Army WWII fame. Those were purposefully-designed to be heavy-duty load-carriers for military usage. They could, in extremis, carry 12000 lbs on hard dry roads. Compare the automotive bits between those and an AA and it's like comparing the workings of your average small lawn tractor of bobcat to a D-10 CAT dozer. I own a Pinzgauer tactical truck. It's rated as a 1.25 ton truck - it's built to carry that 1.25 tons cross-country. It's bits are much beefier than those of a Jeep - a vehicle of almost identical size but actually rated to carry 0.25 tons cross-country.

As we know, folks often over-load vehicles in practice, both in the military and civilian worlds. This is one of the reasons why we have truck-scales on US highway systems... I know plenty of people who have packed a LOT more than the supposed "rated" load of 1000 Lbs into their standard Ford F150 pickup... (I once stupidly managed about 4100 lbs... stopping was a Beast - with all the brakes!). So, I would be pretty sure that some Germans did try to stuff a gun into a captured "1.5 ton" GAZ AA. Did they dare try to take it off the already seriously - limited "roads" common to much of wartime Russia? Busted axles and lost gun would likely have been the quick and terminal result. Did they try to crew and fire a FlaK 37 or 43 off a GAZ AA? Maybe. People do lots of stuff once.

Just some thoughts. Load that gun on, but maybe make it look like cargo and not like a "gun-truck"?

Cheers! Bob

Bob,

Thanks for the information. Are you certain that Ford designed the -AA with a ROAD based 1.5T cargo load? I only ask because a LOT of the places those trucks went at the time were definately NOT improved roads, or barely even roads at all. I have walked some of those old trails in South Dakota and Nebraska and I have to say, wagon ruts for a road ain't much of a road.

You commentary on overloading is appreciated but I also know that ratings are listed for reasons and engineers, whom I seem to know WAY too many of, are extremely anal about these details.

Hence, I wonder if the rating for the -AA is for on road or cross country?

Side note - I can easily see the German's putting a 3.7cm Flak on a -MM for mobile air defence in a city or such. And it could very easily be fired and used in that scenario. The question that comes to mind is, by the time they were desperate for air defense and cared, would they have had access to a -AA or -MM and would they have used it for mobile air defense or for desperately needed cargo/troop movement?

But thanks guys for the stimulating conversation. I learned a LOT more about truck design than I ever thought I would, and it was interesting. And that we in the USA REALLY need to get on the metric system.

Jacques;

Hi! Probably we need to remember first and foremost that the Ford AA was a strictly civilian vehicle and made in a time that mostly didn't over-engineer cars and most trucks intended for the civilian market. It was, I am sure, produced in part with intent to sell to farmers and other folks living on the "lesser" roads outside the big cities of America. But it wasn't built to be a cross-country mover. The understanding of the times was likely that it could probably go where horse-and-wagon could go - but a bit faster and carry a bit more. There were companies, such as MACK and FWD, which produced costlier, more-capable heavier-duty equipment. The AA was genuinely a "People's truck" meant to be cost-effective. It was a modified passenger car! Us Americans love our little trucks - the Ford T was the first pickup - if "rated" at all, probably realistically good for maybe 1/4 ton on-road (but remembering that folks would drive their "flivers" all over the country-side!). The advantages of the T and the AA trucks were that they were actually light-weight and thus were not fighting their own weight to go places. But they were no sort of hi-powered carriers. In a way, my Pinzgauer - a near-modern military tactical x-country extreme mobility truck - is similar; it, too, is light weight for its size and cargo load limits, and it, too has a small engine and low gearing... creepy-creepy works GREAT for x-country, even in 2wd! The AA did have low gearing (along with its smallish engine) and slow speed. History does tell us that it served well around the world as a common basic truck. It was invaluable in the USSR, which had no native truck industry at all before the war - a cheap, simple, "People's truck". Where even a small and under-powered, no-brakes truck was better than no wheels at all. Like the Opel Blitz and Renault AFM? 2wd trucks, they could carry over-weight slowly on roads, and suffered mightily when the "road" was a sea of mud.

And PS: Probably a few AA or MM did serve the Germans right to the end, I would think. I would even bet a few were motoring around in Berlin in mid-1945!

Bob

Bob, if you are correct about the rating of the Ford-AA, that means that its rated cross country capacity is more like .75T, or 680 kg. Ouch. The Russian rating would then fall to 750 kg cross country. That makes mounting even the little 2.0cm Flak 38 a much more risky endeavor.

And may explain why there are no cool pictures of the Germans making all that early war booty into big time equipment carriers.

Jacques and Bob !

Thank You for good discussion I see here.

Yes, I think, during the preparation of production of Ford AA trucks in Soviet plants some Russian engineer(s) could confuse US "1,5 tons" with metric "1,5 tonnes", because these "1,5" numbers are similar each other; and different words "ton" and "tonne" in English language become the same in Russian language - "tonna" for both words. Moreover, the weights of 1360 kg and 1500 kg are "almost equal".

Another way is, most probably, the translation of Ford technical documentation into Russian language. Possibly, the Russian translators translated directly the US term "1,5 tons" to Russian "1,5 tonnes" - because this number is clear and well understood for any Russian person. But those translators simply forgot to convert that US weight into other weight system.

As to this statement:
I must say, that GAZ-AA/-MM trucks were produced during about 20 year period - from 1932 to 1950 - and were built in 985.000 examples (for comparison - Ford AA was produced in 1927 - 1931), and were in active use up to the end of the Sixties.

Anyway - thank You very much, dear Jacques and Bob, for Your active participation in this discussion.

Boy! Did I open a can of worms. Dare I mention I found the pic that prompted this question and the vehicle was a ZIS-5. (Rated at 3 ton of one sort or another. It was based on a US design too. What, I don't know.) Guess I'll have to hold the SPAAG project till I get a ZIS-5V and a Flak 38. I'll have to figure out something else to jazz up the bed of my GAZ-MM 1943. Replacement T-34 engine and tranny? Thanks for every bodies input and glad I could get such a lengthy discussion going.

Guys: There ARE many pictures (photos) of GAZ-AA / MM trucks bearing various guns.... The Russian quad-mg AA set, the 12.7mm Dshk (doushka), the 25mm 72-K 1940 AA gun, various single and double German MG. It is thus quite reasonable to envision a 2cm FlaK 30 or 38 gun on one of these.

It was a truck, albeit a smallish and not overly-strong one, and both the Sov's and the Germans attempted to mobilize every gun that was available...

In fact... I am staring at my Miniart Gaz-AA 1943 and thinking "2cm FlaK 38 gun-truck!" It could also be my hi-jacking that quad-mg AA mount from the Miniart GAZ-AAA and moving it to an AA...

Just no 37mm guns on a "Polutarka"- no FlaK 36/37 or 43 in action. That would be a toke too much for the old boy!

Bob

Was going to say, I've seen reference of the quad maxim on the AAA and Daska on pretty much anything with wheels. (someone makes a German twin MG-34 AA mount. Might be interesting in an AA/MM. ) I saw a Soviet 25mm AA on a truck but don't remember what truck.) Just to further muddy the waters .... Were then any lend lease 40mm Bofors? 20mm Oerlikin ?

Isn't it a bit of a stretch to argue that because a vehicle carried a quad Maxim, it should be feasible to carry a 2cm FlaK instead? What about the crew and ammunition? Do they run along behind laden with boxes?

And then you have to deal with the stability (or otherwise) as a gun platform once you start firing the thing. The tendency I observe is for mobile AAA to be carried on larger vehicles than one might expect based on what will physically fit. Hence 3t for a 2cm, 4.5t for a Vierling etc..

Robert L.; Hey, Mate!

There are actually several "period" photos around of these AA / MM trucks sporting the many different smaller guns I noted above. I'm not "crypto-citing" someone's claims - just identifying the guns seen mounted (and in some cases, crewed)! LoL!

And so I conjecture that a 2cm FlaK 30 or 38 could be a sort of "direct swap" by weight and size for the M1940 25mm gun. for instance. If an AA was actually seen carrying that crew-served weapon and in action with same, it seems reasonable that a German unit could plop a -38 on and do same-wise. It's no sort of stretch, weight-wise, for that swap. And hardly more for a "stretch" from that quad-Maxim PM10 mount, which all-up may well have tipped out at over 1000lbs US! (The PM10 gun, tripod and quad mount and telescoping pedestal were a heavy, stable assembly. Normally, the Sov's deployed these on the 3-axle AAA trucks! But many photos document this mount on 2-axle AA and MM trucks).

And the 72-K 1940 25mm AA gun seen on AA and MM with crew was no light-weight, either. All-up with its 4-wheel trailer and shield, this weapon in towed form came in around 2700 lbs! So one might expect that the gun and mount minus shields and trailer would still weigh in over 8 - 900 lbs... FlaK 38 would definitely be a contender!

Cheers!

Bob

The weight of the M-4 Quad Maxim AAA system, from Russian sources, is 64.3 kg.

Remember that the 2.0cm Flak 38 is 420 kg.

I cannot find weight data on the 25mm 72-K 1940 AA gun without the "cart" (as it was called in translation) for comparison.

However, I did find this interesting photo of the Gebirgsflak 38 (German airborne lightweight version of the 2.0cm Flak 38):




Have fun with this.

25 mm AA gun on GAZ-MM trucks :





Twin KM-94 25 mm guns on ZiS-12 trucks :



61-K 37 mm AA gun experimentally fitted to a ZiS-32 (4x4 variant of the ZiS-5) truck in July 1941 :



H.P.

The standard Zis-5 payload rating was 3 Tonnes. Since this was a Soviet built truck, I am assuming 3 metric tonnes so it should equal 3000 kg. Double the GAZ-AA (or possibly more, from our discussion). No wonder the Russians loved the Zis-5 so much.

Jacques;

I don't want to sound "argumentative", friend, but if anyone thinks that a quad Maxim PM1910 mount and guns weighs "64kg"(about141 US pounds).... They MUST believe that those Sov's had quietly invented and deployed some sort of miracle metal!

Seriously; The 7.62mm M1931 4M ZPU quad-mount Maxim weighed 460kg without ammo or water or crew or spare-parts. Which makes this one right about 1012 US pounds. Please see
https://www.quartermastersection.com/russian/artillery/854/ZPU To quote their "notes": [The 4M ZPU (Счетверённая зенитно-пулемётная установка) was a quad machine gun system designed as a light anti-aircraft weapon. It consisting of four maxim machine guns and was developed by Tokarev. It was effective against low flying aircraft and was capable of up to 2.400 rounds per minute. It was fed by 1000 round belts that were stored in ammunition boxes and located underneath each barrel. It was a heavy weapon and was mounted on various trucks or static mounts.]

At this weight (460kg), a 2cm FlaK 20 would be a definite "ringer".

Bob

PS: Let's be sure that no-one ever mounted a FlaK 38 onto a VW "schwimmwagen". If nobody gets any other "clues" as to the facetiousness of that photo-shop picture.... Note that the rear suspension is not compressed at all, even though there is supposedly an 800 lb gun and a gunner sitting directly over that rear-end. It's a vee-dub, not a cargo-truck. Compare that image with those of the twin 37 mount and some other mount in those Xis-5 3-tonne trucks, and note how those rear suspensions are definitely "loaded".

One more inspirational image:


/ Robin