Sherman Tank Site News Post 17: Summer is here, I have all kinds of content for updates, but less time than I would like.
I am always tweaking the site and doing minor edits, but in the past few weeks, I’ve had time for some more major projects. There have been a few minor projects worth noting as well.
The Editor over at Tank and AFV News sent me some very interesting reports that give a very interesting look into the Army’s search for a suitable tank Motor.
THE NEW REPORTS! (They are new to the site, not new)
Ordnance Development of the Wright-Continental R-975 Radial Engine: This report is very interesting. It shows how long, and just how far the Army and Continental went to try and improve the life of the R-975 tank motor. By the time they were done, it was almost a new motor, but still not a great tank motor. Good enough for sure, but no Ford GAA, or as reliable as even the A-57!
Ordnance Development of the Chrysler a-57 Multibank Tank Engine:This report is just like the one on the R-975, but all about my favorite tank motor, the Mighty A-57! This motor became shockingly reliable for how complicated it was. What made it great was the complication only came in mating the five motors, the banks themselves were solid, wells designed, motors.
These reports will give you a very good look into why the US Army chose the motors they did and the story behind getting each one to work as a tank motor. They are interesting stories in their own right.
Post 72: Army Motors: How the Army Updated the Armies Mechanics!
Over the years, I’ve run into the Army’s PS Magazines, the comic book style magazine distributed around the army to advise the troops in language they could too, but they were all post-WWII so of limited interest to the Sherman Tank Fanatic. RadioNerds has all or almost all of the PS Mags for download, and they are a fun read. RadioNerds is a really Fantastic site, and when I found out there was a WWII Magazine for the same purpose, though more Vehicle specific, and was not surprised to find RadioNerds also has all or just about all of them too!
The Army Motors magazines start pre-WWII, in may of 1940, and they really do not have much of interest to the Sherman fanatic until the 1943 issue, and then they have all kinds of fun information. This does not mean those pre 43 issues are not interesting. They give you a look into the problems the army was running into as it was growing, and one of those problems was draftees ruining everything!
What I mean by this is the main push of just about every issue is, follow the maintenance schedule and not be creative in trying figure out better or easier ways to do the maintenance. Some other problems would be not driving properly or even warming vehicles up right. General carelessness seemed to be enemy number 1.
Accident were another big subject across the board, I even found a chart of deaths and there causes. Horseplay was another one, with power tools in particular, got mentioned in several issues. This one I thought was amusing, and reminded me of all the times I’ve worked with men and around tools. Jokes and pranks were played, and it was just life, no need to involve HR or anything.
The general tone of these magazines was humorous, and they have several set ‘Departments’ like Connie Rodd Bulliton board, and the Rumors Department, with an Outhouse as a logo. There were lots of illustrations and comics, and they went color in late 43.
The early and late versions of later versions of Connie Rodd.
Here are some interesting examples.
A letter from a satisfied customer.
Don’t waste rubber, it makes Hitler happy, that’s his happy face.
This cartoon is a little disturbing, but the chart explains the US Vehicle maintenance system.
Bibliography and sources: So here are all my sources
So yes, I know the site would be better with a list of sources, and this is going to be that post for now. I will also, as I review and rewrite all the articles over time, add them to each post.
A bit about the site, and myself, I’m just a guy who really likes WWII history, and more specifically, WWII tank history. I am not an expert on the Sherman, but I do know a hell of a lot about it, and I have a lot of opinions about it as well, and much of this site is me sharing that opinion. The hard data is not my opinion, the specifications, and other details are not my opinion and come from many different sources. Most of these are listed in the book review and links section. There is even a data post with a whole lot of useful information in picture format of various documents.
First and foremost, most of the minutia details come from reading the Sherman Minutia Website a lot and looking through the Son of a Sherman book. Between these two sources, you can answer almost any question about a production detail on a Sherman you may have, and the nice thing about the SMW is it’s always being updated. I only cover these details in a very general way, I could never do it as well as the book or site.
My next big source of information is period literature and manuals. If you haven’t noticed, I have a very large selection of technical manuals and field manuals on my website, all available for download, for free. I’ve collected a huge number of the things over the years, most in PDF format, but a few in real paper, and I’ve read a hell of a lot of them. I am missing a few key Technical Manuals, like one on the M4/M4A1, I have the M4A2, A3 and A4 covered though, and several TDs and the Lee. I’m pretty confident I could start up and drive around and M4A2 or A3 or even A4 and adjust the clutch linkage and do a host of other maintenance tasks from reading through the manuals on how to do them. These old tanks are so similar to old cars is funny, and if you know a good bit about old cars the manuals should be very easy to follow, the big difference is the size of the tools and weights involved.
Along with the TM and FMs, I’ve hosted a lot of other documents I’ve found on the internet, from battalion and division histories, the very interesting Combat Lessons booklets the DOD put out during WWII, and I’ve taken information from all these sources.
Now for the books, so many books, most of these I own, and love, but a few I only have in PDF. I already mentioned Son of a Sherman Volume one. If you have any interest in the Sherman tank, you should by the book while it’s in print and reasonable in price, it’s fantastic. It also had some of the better info I used in the factories post. It’s to late to get this book at regular price now, and new and used copies are going for 300 to 700 bucks!
Sherman: A History of the American Medium Tank, by RP Hunnicutt is the holy grail of Sherman books. It is filled with so much information about the production history, use, design, modifications, and hard specifications, that much of the data on this site comes from this book. The gun chart data came from here, all the data sheets, and a lot of the future things that almost made it came from here as well. This book is currently in print again, for 60 buck paperback, 70 hardbacks. Buy it now, before it goes back into the hundreds after going out of print. Though slightly dated in is the short history of battle sections, it is still an amazing book, and really the only hard technical history of the Sherman that is really great. Also always keep your eye out for an original printing, the photos are much better.
Armored Thunderbolt: The US Army Sherman in WWII, by Steven Zaloga this book, when combined with Son of a Sherman and RP Hunnicutt’s Sherman book will give you a very good knowledge base on both the technical and historical histories of the tank, and if you throw in Son of a Sherman you have all the minute details covered. With these three books, you can really get a good idea how wrong the pop culture opinion of the Sherman and German armor in general really is. So a little more about this book, Zaloga covers both the design history, though not in minute detail, (You will not find detailed specification sheets or a breakdown of the exact details of the differences in all Sherman models) but he does cover much more of the politics and decision making that led to some of the key problems that popped up with the Sherman, US Tank design, and armor tactics. In this book and several Interesting interviews, he really covers why Belton Cooper of Deathtraps fame was so wrong. He also has a lot of the numbers in his book backing up the Sherman performing in battle better than the Panther. Zaloga is a prolific writer and has put a lot down on paper about the Sherman, and I’ve read almost all of it, aside from a few older Osprey New Vanguard books. This man, almost as much as R.P. Hunnicutt is responsible for bringing out the truth about the Sherman tank.
The Tank Killers, Steel Victory, and the Infantry’s Armor, by Harry Yeide, These books are another big source they are really great books covering the use of Tank Destroyers and the Separate Tank Battalions. Yeide is both knowledgeable and easy to read, and I will continue to buy every book he puts out.
Marine Tank battles of the Pacific by Oscar Gilbert, in comparison, to Sherman use elsewhere, until recently info on the Shermans use in the Pacific was pretty light. This book is specific to the Marines and covers more than just Shermans use, but it does a pretty good job of covering each battle, and most of the info, along with some histories from the Marine Corps was used for the old Tarawa post. His book on Marine tank use in Korea also has some Sherman use covered and is a good read as well.
Tanks in Hell by Oscar Gilbert and Romain Cansiere is a very recent and very detailed study of the use of Marine Shermans on Tarawa. It is the most detailed history available on the Shermans use in that battle and clears up some mysteries and misconceptions. It was a great read and I just finished it up.
There are so many books on the Sherman out there, I’ve tried to read any I could, but the ones listed are the best and most important. I do not read books just on the Sherman tank, and at one time was what one could consider a wehraboo, and I know the guy who invented the word too, so I have that going for me. Anyway, while a wehraboo, I collected some of the premium good source books on German tanks. Reading through Panther Tank by Thomas L Jentz started me down the path to salvation, the combat readiness reports found in that book; even on the late model G Panther are truly pathetic, though it is really a beautiful book, Jentz was only against listing source material. I also have Panther and its Variants by Walter Speilberger, another beautiful book, filled with beautiful illustrations on a tank so unreliable to be almost useless. I have Jentz’s two books on the Tiger, D.W to Tiger I and Tiger I&II Combat tactics. Also very nice books but based on old outdated historical information when it comes to the unit histories, but boy are the pictures great. I have Speilburger’s books on the Panzer III and IV, both great books, and the subject matter is more interesting since these were the real stars of the German tank design, in that at least they worked and offered real value to the German Army. I’ve read Tigers in the mud and even enjoyed it. There are of course more, but that covers the really big stuff/good stuff.
Other important sources are sites like Archive Awareness, who author takes Russian Soviet-era archive documents and translates them and offers opinions on them. He has some very interesting information on the Sherman tank on his site, and far more on Russian tanks and German lies. Some say he is biased, but if he is, it’s against the Nazi propaganda that still lives on to stink up the world, and I’m fine with that. Other good sites include Tank and AFV news, and the Lone Sentry.
The Chieftains Hatch of Wargaming fame, like him or not has produced some very interesting new information about various tanks, and his publication of the French post-war report on Panther use is a real eye-opener and was groundbreaking info. I have links to many of his very interesting posts in the links section. Like World of Tanks or not, they have dropped a lot of real cash on restoring real tanks, and paying real researchers to unearth interesting tank information, they deserve some real credit for furthering the modern understanding of Armor. Wargaming also got a lot of armor experts in one place as a panel for their Operation Think Tank series and let the crowd ask questions, it is on YouTube and filled with very interesting info.
If I have it listed on my links, information from their website has probably contributed to a post on this site.
Now a final bit about sources and this site, all the information in the various posts is true to the best of my knowledge and sources. Some information, mostly image captions are very generic and often wrong, and many helpful people have posted corrections, and I’m always grateful for it this help. If you think I’m wrong on something, and you can back it up with sourced info, by all means, contact me through the site email, or posting a comment so I can correct any mistakes. I try and keep the site from being about my ego in any way, and will listen to reasonable people with reasonable arguments and most importantly, data and source info to back it up. Don’t bother if your ‘source info’ originated with a German wartime SS source, their wartime numbers are not at all accurate, and even the German army discounted them.
On a final note, am I a fanboy of the Sherman, in a sense, I suppose, but a true fanboy does not understand the flaws of their subject of obsession, and in my case, that’s not true. I know theSherman had flaws, it like all things created by man, was an engineering tradeoff, and the ones they chose, were the right ones for the US Army in WWII, and even Shermans armed with only the 75mm could have carried the day in Europe. Or that’s my opinion anyway, but don’t let my opinions scare you away from all the hard data on the site.
After just over two years in operation, this site has grown past 350,000 words, with a huge number of Sherman photos and drawings, many of the drawings pretty rare. I have more information on the motors and powertrain of the Sherman series than any site on the net. This site has more technical manuals, and field manuals on the Sherman and US Armor use than any site I know of.
This site is largely a one-man operation, and with that much content there will be typos and grammar mistakes, and I apologize and fixe them when I find them. This site has been funded out of my own pocket, and if you count book purchases, the cost has gotten significant, but the content will always remain free, and ad-free.
The Sherman Motors: Why So Many, And Why The Weird Ones?
The Sherman had four different motors that made it into production tanks. The R975 radial, The GM 6046 ‘twin’ diesel, the A57 multibank, and the Ford GAA V8. There was also a Caterpillar motor they were trying out I cover in the Shermans of the Future section.
There are several reasons the US went with the radial aircraft engine instead of a dedicated tank power plant, and this was mostly due to lack of money to develop tanks and their drivetrains between wars. When the US got serious about tank motors, there were a limited number of choices and the R975 was the best one. Then they turned to the US auto industry for other motor ideas, but only after the war was clearly looming. The US Government went to General Motors, and Chrysler, and asked for a tank motor ASAP, they got motors ASAP, but they were lash-ups, but they ultimately worked well. In this case, desperation produced the weird motors, and American automotive know-how, made them reliable.
GM came up with their twin bus motor, the 6046 and it was well-liked right from the beginning. Then Chrysler came out with the nutty but fantastic A57. The US Army didn’t like either and didn’t want to even use them for training. If the British hadn’t been willing to take the A57 versions, the Army would have regulated them to training use only. It wouldn’t be until Ford figured out the bugs in the GAA V8 that the US Army would make the switch from the R975. R975 powered M4s and M4A1s would serve with the US Army until the end of the war in just about every unit that used Shermans though, and they would not be phased out until after the war.
Post-war many A4 tanks would have R975s put in them, or in much rarer cases, the 6046. Parts of the A57 became rare post-war, and people who knew how to keep them working were probably rarer. I’m pretty sure almost all A4s used post the 50s were converted to one or the other of these motors. Conversions to the Ford GAA were not done as far as I can tell, I think because the US Army was stingy with this model and spares for it, so they could keep them for their own use or close allies.
The Continental R975 C1/C4: The Motor the Sherman was designed around
The Continental R975 C1/C4: Type:9 cylinder, 4 cycle, radial Cooling system:Air Ignition: Magneto Displacement:973 CI Bore and stroke:5×5.5 inchesCompression Ratio:5.7:1 Net Horsepower: C1/C4 350/400 hp Gross Horsepower:C1/C4 400/460 hp Net Torque: C1/C4 800/ft-lb/940/ft-lbGross Torque: C1/C4 890ft-lb/1025ft-lb Weight:1137 lbs dryFuel:80 Octane gasolineEngine Oil Capacity:36 quarts
This motor was a license-built version of the Wright R-975 built by Continental for tank use. It had been around nearly ten years and used in civil aviation before the army started putting it in tanks, starting with the M2 medium in 1939, and would go on to produce more R-975s than Wright ever would, 53,000 motors total. The military version put out more horsepower than the civil version as well. This was a solid and reliable tank motor, but not ideal. It was a little underpowered and had to be revved up a lot to get the tank moving. The Army considered this a superior choice over the 6046 diesel and A57 motors, probably because it required a lot less maintenance than the other two motor choices. This motor would be swapped into M4A4 hulls by the French post-war, the French would use the A4, and A2 with the original motors during the war.
Another reason the motor was not ideal was the shape, the R975 is wide and tall, and this dictated how large the rear hull of the tank had to be. The only motor larger was the A57, and it was huge. There are still a lot of Shermans still running with this motor, either in civilian collections, or museums that keep running tanks.
The General Motors 6046: The Motor GM Came Up With To Power The Sherman
The General Motors 6046: Type:12 cylinder, 2-cycle, twin in-line diesel Cooling system:LiquidIgnition: compression Displacement:850 ciBore and stroke:4.25×5 inchesCompression Ratio:16:1 Net Horsepower: 375 Gross Horsepower:410 Net Torque: 1000 ft-lbsGross Torque: 885-lb Weight:5110 lbs. dryFuel:40 cetane diesel oilEngine Oil Capacity:28 quarts
First used in the M3A3 and M3A5 and then in the M4A2. This motor tied two GM supercharged truck diesel together on a common crankcase. The motors could be run independently, so if one was damaged the other could be used to get the tank back to a repair depot, or to keep fighting. The engine weighed more than the R975 but had better torque characteristics, and the tanks with this motor handled low-speed operation better because of the superior torque.
This version was ruled out for use by the Army because they didn’t want to complicate the tank supply chain by adding another fuel to it. This motor was well-liked by its users, and the only version of the Sherman the Soviet Union would take via lend-lease were the ones powered by this motor. The Army testing of this motor found it was as reliable as or more so than the R975.
This motor would run and drive the tank if one of the diesels failed. It has also been reported the Russians would use the ability to only run half the motor to sneak the tanks closer to German lines without being heard. They were impressed with how quiet the Shermans tracks were.
The early drawbacks to this motor were tied to its air cleaner system for the motors; they would clog quickly and required a lot of maintenance. Getting the two clutches for the motors synchronized was difficult on early tanks with these motors as well and this made for short clutch life. There were some other teething troubles with the fuel injectors and other problems, but these would all be solved early in the M4A2 productions, including improved injectors, air cleaners, and clutch system.
The US Army hadn’t wanted to use tanks with this motor in combat, but they ended up doing so since this motor also powered the M10.
The Chrysler A57 Multibank: The Motor Chrysler Came Up With To Power Tanks, It Was Crazy, And It Worked!
The Chrysler A57 multibank: Type:30–cylinder, 4-cycle, multibank Cooling system:LiquidIgnition: Battery Displacement:1253 ciBore and stroke:4.37×4.5 inchesCompression Ratio:6.2:1 Net Horsepower: 370 Gross Horsepower:425 Net Torque: 1020 ft-lbsGross Torque: 1060 ft-lbs Weight:5400 lbs. dryFuel:80 octane gasolineEngine Oil Capacity:32 quarts
This motor was a bit of an orphan in US Service. It powered the M3A4 and M4A4. The Army used the motor for training and tried to pawn a few off on the Marines. That lasted about two months at the Marine Tank School. The ever-growing need for tanks by the British ultimately solved what to do with the tanks that ended up with this motor. They would end up taking nearly 8000 of them. Chrysler sent tech reps to England with these tanks and showed the maintenance crews how to keep them running. This worked well and the engines served their purpose with little trouble. Often powering the best pure AT version of the Sherman, the Sherman VC Firefly. This motor saw a lot of use, during the war, and after with many countries being given Firefly Shermans to help out their recovering militaries. Some even ended up in South America, but I’m not sure what versions. This is my favorite Sherman motor because it’s so absurdly complicated, it’s almost German, but it actually worked, so not German at all.
This motor was fairly robust and would continue to run and allow the tank to move with three of the five-cylinder banks not working. This would make the tank severely underpowered but would be useful to get it back to the repair yard or onto a dragon wagon. I’m sure it was much more common to have one of the five not operating right, and that level of power loss would be an annoyance, but wouldn’t keep the tank from fighting if it was really needed.
During the war, Chrysler really went to bat to keep these motors working well. Since it was based on a motor already long in production, spare parts were readily available. I’m not sure how long support for the motor lasted after the war. I doubt it was very long, and American car parts were probably not easy to acquire to keep these motors running. Because of this, the M4A4, more than any other model seems to have its engine replaced in post-war service. I’ve read about the twin diesel and the R975 being swapped in. There are a few M4A4s around in Europe with running A57 motors, both fireflies if I recall right. You have to love anyone willing to keep one of these motors running.
Daily maintenance could be done with the motor in the tank, carburetor and timing adjustments, fluids and filters, and things like that. If anything major needed to be fixed, one of the motors had a bad piston or valve, or even something minor like a big vacuum leak on the intake of one of the motors, or even a leak in the cooling system, the whole motor would have to be pulled. Chrysler knew this and made getting the motor in and out as easy as possible, including huge lifting eyes built on the common block to help lift the motor out. The British probably had several depots set up to rebuild A57 power packs that were in need of major work, and Chrysler made a lot of spare motors and parts to support the motor.
To be fair, many serious problems with the other tank motors would require pulling the motor to fix them as well.
The Ford Motor Company GAA V8: The Best Sherman Motor
The Ford GAA: Type: 8 cylinders, 4-cycle, 60-degree V8 Cooling system:LiquidIgnition:Magneto Displacement: 1100 ciBore and stroke:5.4 x 6 inchesCompression Ratio:7.5:1 Net Horsepower:450 Gross Horsepower:500 Net Torque: 950 ft-lbs Gross Torque:1040 ft-lbs Weight:1560 lbs. dry Fuel:80 octane gasolineEngine Oil Capacity:32 quarts
The Ford GAA only made it into one Lee as a testbed. But it powered a lot of Shermans, both large and small hatch. It would go on to be the motor of choice for the US Army for the rest of the war, and in the next tank, the M26. Just look at the numbers above and compare them to the rest of the motors. The GAA is really a much better motor for a tank in the Shermans weight range. This tank was not lend-leased to the other allies in large numbers if at all. The USSR may have gotten one to evaluate, the UK too, but the Army wanted to switch over to this and stop using R975 powered tanks. After the war, the only Shermans they kept were M4A3 76 w tanks, and over time they converted as many of these to HVSS suspension as possible. They went as far as swapping T23 turrets from M4A1 76 W tanks onto M4A3 75 hulls. The army would produce several other gas-powered tank engines, but none would really shine like this one did in the Sherman.
The motor started life as a V12 Ford had designed to compete with the Rolls Royce Merlin, after a deal to produce the RR engine fell through. Ford was incensed that a deal could not be worked out and decided to build his own V12 aircraft motor. When he tried to sell it to the Army he was turned down, but later when the army needed tank motors he used the V12 as a basis for the V8, by removing 4 cylinders. As a tank motor, it was under very low stress putting out only 500 horsepower, and could have been really upped in horsepower with a few tweaks.
This motor does not get much credit for how advanced it was. The much talked about, and unreliable as hell, German Maybach HL 230 P30, the motor used to power the Tigers, and Panther tanks, was not nearly as advanced, or as reliable as this amazing V8. This V8 is apparently the largest gas-powered all-aluminum V8 ever produced. It has some very advanced features, even for a modern V8, like a one-piece cast aluminum block with dual overhead cams and four valves per cylinder a true, dual, overhead, cam, motor, or DOHC. It had a very innovative 8-way power drive system for its accessories, like the generators, fuel and water pumps, and two magnetos. The motor used no belts or chains, everything was gear and shaft driven.
This motor saw post-war use in civilian hands, from powering logging equipment, to use as stationary pump motors. The most interesting post-war use is in pro-tractor pulling and hotrod use. These installations in most cases just update the intake and exhaust using modern carbs, but in one crazy case down in Brazil they have updated a GAA with coil and spark plug and crank sensor` computerized ignition, fuel injection and twin turbos, and just 8 pounds of boost it makes 1500 hp, with a higher boost number the engine is capable of 3000 HP. For more info on these modifications and some pics, check out this link.
Sources: Sherman by Hunnicutt, The Sherman Minutia Site, Son of a Sherman by Stansell and Laughlin, M4 Sherman tank at war by Green, Tanks are a Might Fine Thing by Stout, TM9-731B M4A2, TM9-731G M10A1, TM9-745 GMC M36B2, TM9-748 GMC M36B1, TM9-750M3, TM9-752 M4A3, TM9-754 M4A4, TM9-759 M4A3, TM9-1725 R975 C4, TM9-1731B Ford motors(GAA, GAF, GAN), TM9-1750F A57 Multibank