Your M4 Tank Steering Brakes Should Work Gentle’n Easy. If not – Here’s what to do and how to do it. A Brand-new procedure – Easier, clearer, and completer than anything in your TM or Anyplace else.
This Army Motors article is from May of 44s, issue of Army Motors, and outlines an easier and better way to adjust the Sherman or any other vehicle based on the M4 Chassis steering system. Don’t miss the complete section of Sherman Manual TM9-7018 Medium Tank M4A3, from September of 1954, posted below the Army Motors Story.
Read the pages of TM9-7018 Yourself, and compare: Medium Tank M4A3, 1953 has this to say about the steering system and how to tune it.
This is the section of the last Army Manual on the Sherman, this should be the final authority on how to maintain the steering system on the Sherman. It seems to match well with Army motors article. That’s no surprise, by 1944 the Sherman powertrain was very mature, and I’m sure they had the vast majority of the problems worked out by then.
The main difference is the Army motos article presents a specific chunk of the info found in this section of the manual and breaks it down with more pictures and simple instructions. This was a good thing, people have trouble with written directions, and pictures really help. The biggest problem with written direction really is when it does not get read.
If I had to do the job, I’d want both and anything else I could get my hands on. The common theme though, from the Army Motors Mags is, the vast majority of problems with army equipment, that caused tanks, trucks, or anything else mechanical to break down, was either lack of proper maintenance, or improper use. The biggest culprit being bad drivers, who actually drove bad, or neglected their duty to keep the vehicle properly maintained, or both.
One other interesting thing made clear by the Army Motors Article, is that the new double anchor braking system could be retrofitted into the older three-part differential cover. I didn’t want to assume anything, but the is instructions for adjusting the controls for the double anchor setup on the three part differential housing, so I think that settles. it.
Here are some other images of the steering brake system, from the technical and Ord manuals.
Well, I hope that leaves few if any questions about adjusting and maintaining the Shermans brakes. I’m sure there are still some real-world tricks the men still working on the still running Shermans of the world could add too, but that will have to wait until I figure out how to find those people and interview them somehow.
My greatest hope would be one of the men out there restoring one of those beasts might even get the littlest bit of help from this post, because that would be awesome.
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.
Sherman Tank Site Post 73: Articles from Army Motors Episode #1
This is the first in a series of posts I’m going to do highlighting the Sherman or M4 series-related vehicle, articles I’ve found. With some commentary, though some of these articles are so good they speak for themselves.
Give Your Tank a Brake!
This article surprised me, because in the world of 4 wheel drive, compression braking is commonly used to control a vehicle on steep hill descents, and some vehicles have very low gears in their transfer case for this purpose, among others. I bought a Jeep Rubicon because it came with a Transfercase to do this.
A tank is not a Jeep though, so I clearly get the point of the article. Also, as for using the engine to brake, I’ve never been big on downshifting for that reason, even in cars and Jeeps. I once had a conversation with my wife, who was big on downshifting, about the cost and labor of a new set of brake pads, versus a new clutch. She agreed once we talked about the labor involved.
The Transmission, Differential, and Final Drives: Called The ‘Powertrain’ The Sherman’s Was Very Well Designed.
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.
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.
Now a bit about gear ratios, for those who are not gearheads, 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 is, 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.
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 understand the gear ratios 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.
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 neutral, 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.
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.