Category Archives: Powertrain

Sherman Tank Site: News Post 12, pictures and cleaning them up, a lot of them.

Sherman Tank Site: News Post 12, things have been changing, its all behind the scenes.

I’ve gotten my hands on a lot of manuals, and they are all great for gathering info on the Sherman, because you can almost always read them. The picture quality varies a huge amount depending on how it was created. There are some very common and easy to find  Sherman manuals with terrible pictures. For example the two I have on the M4A3, and the manual on the Ford GAA, both were probably photocopied multiple times, then scanned on a really early scanner.

This means, the pictures at best, are mostly black blobs, and even the text isn’t great. All isn’t lost with these, as the line drawings usually come through ok.  In some cases the manuals being sold online are these terrible photo copies printed into a cheap book with no improvements to the quality at all.

Some of these manuals have been scanned in by people with decent scanners, and these though much larger, have much nicer photo quality. Even if the scans are good, the original has to be good as well, and in some cases that’s really mixed.  I have several, scanned at very high resolution, making them restorable, to some degree.

I’ve done the most work on the Ford GAA imaged I have, and the tranny. Here is a selection of the ones I’ve done, but not all. Check out the power train and GAA pages for all of them. These are relaxing to do, and I have a ton to work with so keep checking around the site!

#69 Shermans you can see running: The Planes of Fame of fame Air Museum

Shermans Tanks In real Life: The Planes of Fame of fame Air Museum

Owning and flying WWII airplanes has been a thing much longer than restoring running tanks, and to this day, WWII aircraft tend to get more attention from Americans than armor or ships. That’s changed a lot over the years, and armor is more popular than ever with collectors, museums and the general public.  There are several Tank museums or businesses around the country with running Shermans. The one we are going to talk about today is the Planes of Fame Air Museum, it is legendary in the Warbird world, because it has so many interesting and rare aircraft. It also has a long, history, and saved some amazing planes along the way, and one tank.

The Planes of Fame air museum has been around so long, it surely had a hand it kicking off the interest in Warbirds that has been popular in the United States since WWII. My Dad, a Baby Boomer, loved warbirds, and his love transferred right over to me, and I ran with it buying more books on airplanes, and tanks than he ever did, and I still have them al.  When I was a kid, we went to the Reno Air Races, and I probably saw Steve Hinton, the President of Planes of Fame flying a racer.  There is something about the roar of a warbird flying by that really gives you a sense of what seeing planes like that filling the sky in the mid-40s must have been like. They have a special sound, and hopefully this is a sound we will hear for decades to come.

Planes of fame got started in the 50s when Ed Maloney started collecting airplanes on a minuscule budget, his museums moved around, but really took root at Chino Airport, where Planes of Fame is to this day. Mr. Maloney had fallen in love with airplanes in high school, and just missed WWII. Shortly after the war he began collecting anything with wings on a shoestring budget for his future airplane museum. He was saddened and disgusted to see the warbirds that helped win WWII unceremoniously melted down for Scrap or for a lucky few to rot away on a remote part of an airport. I know the feeling, it makes me deeply sad to see the piles of P-38s bulldozed off a cliff in the Philippines, because flying them home was a waste of time and money…

By the 60s Ed Maloney had achieved his goal of building a museum and around the same time found a Sherman tank on range on Edwards Air Force base while he was scrounging for B-17 parts. He managed to buy the tank for $1!  That’s not even the best part of the story! The Sherman, a very early production M4A1 75 tank, still ran! It had been sitting on Edwards for at least a decade untouched, and they got it running. The tanks interior was not gutted, though some things like the hull ammo boxes had been removed a lot of the important parts were still there. They collected more parts over the years, and serious restoration started in the 80s and continues even now.

Image from Air & Space magazine, of Ed Moloney at Planes of Fame.

Ed died in 2016, and it was a huge loss for the aviation community. Sometimes, when a man with a love for, and a collection of things like airplanes or tanks, when the man passes on, his labor of love dies with him, I know of a least two cases.  The Littlefield collection only lasted a few years before his widow grew tired of it and donated it to a great museum on the east coast, but to build a place to keep it they sold most of it off, and now can’t build the new facility because of zoning problems.  That wasn’t a worry of Ed Maloney, because PoF is a family affair. Steve Hinton, who took thinks over when Ed passed, has been around the place since he was a kid, and his best friend was Ed’s son. I’m also pretty sure Steve married Ed’s daughter! Planes of Fame lives on, stronger than ever, and with another generation working and flying the planes, I think they have a bright future.

This image is from Warbird Depot, a great site for the airplane lover! This is the Planes of fame F4U-1 Corsair, one of the earliest flying Corsairs!

Now you might be wondering how a bunch  of airplane people can keep a tank working, but trust me, they have guys there who can keep an F4U-1 Corsair, with a magnificent Pratt and Whitney R-2800 running, they can figure out a simple Sherman. The nice thing about a Tank is it handles the weather a lot better than an Airplane, though being stored outside unprotected still isn’t good for them. The Sherman in particular has some very sturdy components, and more often than not, if the powertrain remained sealed up, even after decades on the firing range, if it didn’t get penetrated, they rarely needed much work to be operational again. The engines are a bit less robust, but in a nice warm dry environment, they could last a surprising amount of time as well.

Currently the Planes of Fame M4A1 is about 50% complete, and they restore a little more every year, as money and parts allow. I’m sure in some cases things have to be fabricated. It has a little Joe back auxiliary generator inside, has a working stock electric traverse system, but the stabilizer needs a little more work. The electric firing system works, and though the main gun is de-milled, it can still fire 75mm blanks. A blank firing co-ax M1919 machine gun can be fired with the foot switch, just like the main gun. The intercom is complete and works at all stations, as does all the interior lighting. A place like PoF probably has little trouble keeping the R-975 radial running either.

This summer the turret comes off, new ammo boxes go in and they will complete the interiors restoration. The M4A1 is already a part of their shows, but it is also available to rent, TV, Movies, Weddings, you name it, I could see an M4A1 being a cool addition!  I hope to get down there sometimes in the next year or two and check the place out.

The real Zero planes of fame has, with the real motor that belongs in it, and it was used in the movie Pearl Harbor, making a not so great movie a must see. Image from the wonderful

If you are in the area and have even the smallest interest in aviation, you owe yourself a trip to Planes of Fame Air Museum in Chino California. The Sherman tank is of course going to see all on its own, but they also have a real Japanese Zero, with its correct engine and it flies! Even crazier? It was used in the Ben Aflack movie Pearl Harbor! Steve did all the flying, but they wouldn’t let him shoot Ben down for real!

Steve Hinton in front of an F-86 Sabre. Image from Warbird News.

#36 The Transmission, Differential, and Final Drives: Called the ‘Powertrain’ and It Was Great On The Sherman!

The Transmission, Differential, and Final Drives: Called The ‘Powertrain’ The Sherman’s Was Very Well Designed.

Sherman transmission

The Transmission, differential and final drives on the Sherman were very robust from the start of the Sherman design and proved to be rugged enough to take all the upgrades the Sherman had thrown at it over the years. As a combined unit, along with the steering brakes, with the armored differential housing they were referred to as the ‘powertrain’. In most cases a whole powertrain unit would be swapped if any of the major components needed serious work, since it was relatively easy. There were three types of armored covers, a three piece bolt together type, and two cast types. Powertrain units incorporating any of the differential covers could be swapped into any Sherman in place of any other type of powertrain unit. The internals of the three types of differential covers where different though and parts in some cases do not interchange. Hydraulically powered steering was tried on very early M3 Lee tanks, but it was discarded for an all mechanical long lever system used throughout the Lee and Sherman run.

latemodeel powertrain diagram

The final drives and differential had a gear ratio of 2.84:1, limiting the tanks top speed by RPM to 26 miles an hour in the M4A3 version of the tank, and that for only short burst. The RPM limit varied with engine model, and in the Jumbos case, a slightly higher gear ratio of 3.36:1, limiting its top speed to 22 miles an hour but giving the drivetrain a little more mechanical grunt to get the extra weight moving. This was the only modification major enough to be mentioned in any publication I’ve read so far. That says ‘damn good design’ to me. I’ve read several accounts of Sherman restorations being done, where after years on a firing range, or just rotting in a field somewhere, the final drives and differential units needed no mechanical restoration.

M4A2 differential cutaway
Cutaway of an M4A2s differential
M4A2 Final Drive cuttaway
Cutaway of a Sherman final drive.
Sherman final drive herringbone gears and shafts. This image is from the American Fighting Vehicle Vehicle Database.

Now a bit about gear ratios, for those who are not gear heads, before we get into the transmission, since it’s going to have even more confusing gear ratios talked about. The meaning of the gear ratios in the above paragraph are, for every rotation of the drive shaft coming out of the transmission and going into the final drives and differential has to spin 2.84 times to spin the sprocket output shafts one turn.  What determines the Transmissions output rpm is what gear it is in, and what ratio that gear is.  The higher the number, the more mechanical advantage is transferred to the final drives, but lowers the top tanks tops speed in that gear.  If you have driven a manual transmission car, this is why first gear climbs in RPM so fast and each further gear the RPM climbs slower, but the car goes faster, same for the Sherman tank. If you really understand this, you will always get a laugh at the Hollywood portrayal of nitrous oxide; something used in WWII aircraft engines, because they always show it as making the cars top speed faster, when all it can do is improve the acceleration to the mechanically limited top speed.

This M4A3 Powertrain is about to go back into it’s hull

The Sherman transmission has a “Granny” first gear ratio of 7.56:1, the tank isn’t going to be moving faster than 1 or 2 miles per hour before the driver would have to shift.  The next gear up, second is 3.11:1, on level ground, gear two is used to start the tank and drive it at low speeds. Say up to 5 miles an hour, on road and rarely off road third rarely you would then get into third gear, 1.78:1, and up to 8 to 10 mph.  Fourth would be the last gear to see regular use, coming in at an almost one to one, 1.11:1. This is your driving like a bat out of hell 13 to 19 miles an hour gear. Fifth gear is actually an overdrive gear, at 0.73:1, meaning .73 of a turn to spin the tranny output once. Meaning, this has to be taken to into account in calculating the tanks top speed and it could only reach its top speed on good roads in fifth gear! Reverse gear, 5.65:1, was almost as tall as first and really limited the tanks reverse speed. If you understand what be just covered, you can will understand the gear rations listed on your next cars window sticker.  On our example M4A3 at would be screaming along at 2800 rpm, at the tanks 26 mph top speed.


Now that you understand gear ratios you may wonder what the term “Granny” gear means. The ‘Granny’ gear refers to a really high gear ratio gear, almost always first. The Granny gear was used for getting a vehicle started while hauling a big load, trying to tow another tank to get it started or heavy vehicle for the same reason, climbing a steep hill or obstacle, driving through thick mud or deep water or getting another tank or heavy vehicle unstuck from mud or another obstacle. This gear could also be used to slow the tank when going down a steep hill.

Powertrain early, from M4A4

The Sherman Transmission was fully Synchromesh in gears 2 through 5 with first and reverse not needing it.  Synchromesh means you did not have to depress the clutch twice, once to get it into neural, the next to go to the next gear, or “double clutching”. This in theory made the Sherman tank, though a manual transmission that used a clutch, much like any car that has a manual, relatively easy to drive. If you could drive a car from the 30s you could drive a Sherman. There are several Sherman museums that will let you drive one if you have the right amount of money.  From what I understand, the key to how easy the Sherman is to drive comes partly from the motor in it and partly from how much you’re really willing to drive the thing and not worry about breaking it. It’s an American tank people, you can abuse it, it can take it, it’s not a Panther, it was designed with the American young adult of the 40s in mind. Hell, these things were used to tear down buildings post war! They are not delicate.  Anyway, back to what I’ve read about driving a Sherman. The easiest motors are supposed to be the Diesel and Ford GAA, then A57 if it’s running right, then the R975 powered tanks. The R975 because it likes to get up into its higher RPM power band, and stay there for a while, it helps burn off carbon and keeps the plugs un-fowled, is supposed to be the hardest to drive. In contrast, the few places that have running Panther tanks have to be extremely careful who they let drive it, since using some of its design features could destroy the transmission or final drives.

powertrain brake adjeuxtment

The Sherman powertrain was a very tough unit. I know of at least two restorations where the transmission needed little mechanical work. This same transmission, and for the life of me I don’t think I’ve ever seen a name for the original designer/maker, stayed largely unchanged through the full life of the tank. The Israeli Shermans used into the 70s were using original Sherman Transmissions, though probably overhauled. That they could be, and continue to be on overhauled for restored Shermans, kept working, and working well after all those years also screams “DAMN GOOD DESIGN” and it’s a little sad I don’t, we don’t know, who made them or designed them.

rear firewall m4a3 late
The oil cooler shown in this diagram was found in all Sherman models.
This powertrain out of an M4A3 76w tank sat for years, after being abused in a tank used in the demolition of houses. It only needed cosmetic restoration.