Monthly Archives: April 2016

#54 The Escape Hatch, Interior Lighting, Exterior lighting and Auxiliary Generator: They had to go somewhere.

The Escape Hatch, Interior Lighting, Exterior lighting and Auxiliary Generator: Why? Because People Want to Know About Sherman Interior Lighting

The Escape Hatch: If You Can’t Get Out the Top Get Out the Bottom

escape hatch
Sherman hatch this does not seem to have changed much from the start of Sherman production to the end

All Sherman tank production models and most of the TDs and ARVs based on the Sherman had an escape hatch right behind the co driver’s position. The location and size of the hatch stayed the same, but the ones installed on TDs seem to be different than the ones installed on tanks. None seem to have been hinged though, a common field modification was adding steel tabs to one side of the hatch so it doesn’t fall all the way out this was a common modification on both tanks and TD. This field mod was made a factory installation on at least the M36 B2.

M10-36 escape hatch
M36/M10 escape hatch

The escape hatch on early Shermans with a full turret basket was only really usable by the driver and co-driver. The driver would have to climb over the transmission to get to it, but the area was pretty large to get through. The reason the turret crew couldn’t use it, or it would be hard for them to use it, was the turret basket on early Sherman models it was fully screened in.  There were openings, so the loader could reach the hull sponson ammo, but to use these, the turret had to be in the right place and not facing forward. These openings, when turned towards the co-driver or driver would allow them access to the turret, or the turret crew to the hull.

 

When they decided the initial ammo storage layout was too dangerous, they removed the screening, and the ready rounds, making access to the hull for the turret crew much easier, but there was still the turret basket floor, and the braces attaching the floor to the turret to get in the way.  As the Sherman matured, the basket on the second generation Shermans was cut back to a half basket, and then eventually removed. Once this was done, using the floor escape hatch was much more convenient for the turret crew.

The Shermans escape hatch was located just behind the 1-inch thick armor under the driver and BOG, where it was only half an inch thick. Far enough back there was not much of a chance of the crew being seen as they exit.  The hatch was not used for just escape, I’ve read many accounts of the hatch being used to rescue wounded and or just pinned down men under heavy machine gun fire.  The men would be told to lay still, and the tank would be directed onto them by the infantry in the area, in some cases one of them riding in the tank and when close the man on the ground would make sure the tank was going to straddle him and then waited to be run over. Once the tank was over the man, the escape hatch was dropped, the man pulled in and the tank would back out. This could be repeated as needed in the Pacific since in many cases the Japanese had nothing that could take on the Sherman locally.

One final thought on the escape hatch, the reason it was fairly large and far back under the hull was that there were no torsion bars to worry about getting in the way. Later US tanks did have hull escape hatches, but they were usually further forward due to torsion bar use, and different driver’s location. You can see this on the M26 Pershing, where the escape hatches, there was one each for the driver and co-driver, were right under driver and co-drivers station. In some cases large mines could blow this escape hatches up into the crew compartment, injuring the driver or co-driver. This could take place on a Sherman, but no crew member was right over the hatch.

Interior Lighting: Because the Interior of a Tank is Dark, and People want to know About the Lights.

Sherman lights both main types
The early and late style Sherman interior lights. Thanks to Marc S over on the G104 mailing list!

The interior of a Sherman tank is a pretty dark place, even during the middle of the day, particularly on the early models, when buttoned up.  The only light would be what could come in through the various periscopes if they were open, or the DV ports on DV Shermans.  On late model Shermans with the all-around vision cupola would be a little better but still not great. Opening the hatches and the pistol port, of course, helps a lot, but you can’t run that way when they are shooting at your Sherman.

m4a3 hull lighting wiring diagram
M4A3 hull wiring diagram showing crew lights

Now those clever engineers who designed the tank thought about this one, and they provided the early Sherman crew with three interior dome lights in the hull and four or five on later Shermans, and the instrument panel and compass were illuminated.  The turret had an additional one to two interior lights on early tanks, and three on later Shermans. These lights were all three candlepower.

 

M4A3 drivers side
You can see the co-drivers light mounted on the blower in this diagram
blower for the crew
A better view of the light market E in the above diagram

Early Sherman interior lights were white light only, but later ones had a red light as well to help with night vision. The lights are all in series with the master battery switch, so it must be on for them to work. Think 70s car dome light for brightness levels. There was also a third interior light type, used only on 105 Shermans, that didn’t look the same, but I do not have a picture of it at this time.

Exterior Lights: The Sherman Tank Had Those Too!

M4A3 drivers side headlight

The Sherman Tank had to drive on roads, sometimes in traffic, and at night. To facilitate this, the tank had removable headlights and taillights.  The later model Shermans also had provisions for an amiable, removable spotlight mounted on the top of the turret.

M4A3 blackout light drivers side

The Headlights came in two varieties, a regular headlight, and a blackout headlight, both had blackout markers.  They would use the normal headlights anytime being observed at night was not important. If there was any chance of enemy observation, then just the blackout lights would be used. In extreme cases, just the black-out markers could be used.

m4a3 taillight

The tail lights were smaller than the headlights, and there was only one service taillight, and a pair of blackout taillights mounted in a pair of housings on the rear hull.

light switch settings

Mid to latish production turrets and most 76mm turrets had a removable,  paintable from the inside, spotlight added to the top of the turret. Many early Shermans that didn’t have the turret roof spotlight mount had it added during overhauls.

French crew on the background of the tank Sherman M4A2 (76) W of the 2nd company of the 501st Tank Regiment (2 Compagnie de Chars, 501 RCC)
You can just make out the turret spotlight in this photo

The headlights and taillights were controlled from the driver’s panel by a four position switch. All the lights were removable, so they wouldn’t be damaged when the tanks went into combat.

 

The Auxiliary Generator: All Shermans Had One, Even the TDs and ARVs, but they were not always the same unit

 

auxgen early 

The Homelite Model HRUH-28: Was the exact model used in most Sherman based Tanks and TDs; the Army used this Aux Gen well into the 50s. Homelite also made other models for aircraft use, and they may have sold them commercially.  There were a few differences in the installation, on early production Shermans, it was installed with a simple muffler that had an outlet at the rear of the vehicle, and the heat generated by the use of the generator was called an added feature, and was the tanks ‘heater’. Later versions had a ducting system that vented the heat into the engine compartment to help pre-warm the engine in cold weather or vented into the crew compartment to heat it. The ducting added about 15 pounds to the unit, for a total of 140 pounds.

early aux back

The motor that powered it was gas powered, even on the diesel tanks, and was a single cylinder, air-cooled, 2-cycle with a 2 3/8 inch bore and 2 1/8 inch stroke. It operated at 3400 to 3700 rpm and burned half a gallon of gas, mixed with oil for lubrication, an hour.  It could be run on gas 80 to 100 in octane, used a magneto ignition and a forged rod, crank, and piston.  The Generator could be started in two ways, if the tanks batteries had enough juice, it could be started by motorizing the Generator with the battery, or manually, with a supplied rope with a handle, on the starting plate.

m4a4 interior, manual, m4a4
In this interior shot of an M4A4 from TM9-754, you can see the Homelite auxiliary Generator tucked into the corner

The Generator portion of the unit generated 1500 watts, DC, 30 volts. It was shunt-wound for battery charging. The Armature had a high-quality steel core and was laminated, impregnated and backed to give high resistance to oil, moisture, and dust. The field coils were made the same way as the Armature The whole unit, motor, and generator, used ball bearings throughout.

early sherman hull wiring diagram m4a2
M4A2 hull wiring diagram showing Homelite install
early sherman hull wiring diagram m4a2key
Key for the above image.

There was a short 10 item list of things the tank crew could do to maintain the auxiliary generator, and the final one removed it and put the new one/refurbished one in. looking over the technical manual for the generator (TM9-1731K), and reviewing its construction, it was both heavy duty in construction and designed to give long trouble free service.  The unit took the up rear part of the sponson on the driver’s side and had a dome light right near it on most Shermans.

 

 . . .

the mystery aux gen
The four-stroke mystery auxiliary generator

The Mystery Auxiliary Generator:  When I was going through all the Sherman Technical manuals looking for info on the lights and Aux Gen, I found a few references to a model not made by Homelite. What’s interesting about this is, the Homelite tech manual is listed as a reference in most of the Sherman TMs that use it, but the mystery Aux Gen is not. I found most of the specifications for it but not everything and I found a few good pictures in the manuals, though one manual was useless in that area because it’s a horrible scan.

mystery generator installed
As you can see this is a more compact installation

The Motor was a single cylinder like the Homelite, but it was a 4-cycle motor, the Homelite was a 2-cycle. The bore was 2 5/16 inches and the stroke was 2 1/4 inches. It ran between 2300 and 2550 rpm and made 1.6 HP at 2300 rpm.

m4a3 hull wiring system
M4A4 hull wiring diagram showing the location of the more compact unit

The Generator was 6 pole, and compound wound for starting, and shunt wound for generating. I assume it put out about the same amount of power as the Homelite unit, but the technical manuals I have do not state what it produced.

The whole unit appeared to take up less space and maybe the aux generator they used in some wet ammo rack hulls. If anyone has more info on this Auxiliary Generator, please contact me!

different style aux gen

Both units had small fuel tanks in the engine compartment with their own filler caps. In some installs, the gas tank may have been partially mounted inside the crew compartment.  I’m not sure if this version had an oil tank or was like the Homelite, that needed oil mixed into the fuel for oiling. I’m not sure why they used two different unit, the size probably had something to do with it, but it also could have been a supply issue, maybe like with the turret traverse systems, one maker couldn’t keep up?

 

 

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A little note on the Technical Manuals, you would think they would be standardized, and in some ways they are. The early manuals, like the ones on the Lee tank, and early Shermans seem to be much shorter than the later versions, and none seem to cover the tank in the same way. They all seem to have an inventory of what the tank should come with, and it’s really huge, and a section on how to drive and maintain the tank. They all seem to have an electrical section, but what it actually covers varies.  The M4A4 tech manual has a huge section on the motor, but nearly nothing on how to use the main gun.  They do seem to get better as the Sherman aged, but the only late model manuals I have are for the M36B1 (TM9-748, TM9-745) and B2, and a horrible scan of the M4A3 manual(TM9-759). I have much better manuals for the M4A4 and M4A2 though. I really need a high-quality 9-759!

 

#53 Bibliography and sources: Yeah I Know Sources on Each Post Would be Nice, I’m Working on it

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.

Data
Data

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.

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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.

20151026_170409

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 the Sherman 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.

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