Category Archives: Escape hatch

Post # 68 The Chieftain’s Hatch does the M4A1, we review it.

Post # 68 The Chieftain’s Hatch does the M4A1, we review it: A great Hatch!

The video comes in two parts.

The subject of the video is  Black Magic, a small hatch, late production M4A1 if the turret came on it, though the turret or gun mount could be from other tanks. When it comes to restored Sherman tanks, I think being concerned about matching numbers is not a thing that seems to be worried about, and since it was so well designed and built, parts readily interchange. This sherman started life as a canadian Grizzly, basically totally the same as an M4A1 with an extra small hatch in the hull floor.

This tank has almost all the quick fix upgrades, the extra armor over the hull ammo boxes but lacks the cheek armor on the turret, and the turret may, I can’t tell for sure, have the cast in cheek armor, meaning it almost for sure didn’t come on the hull.  It also lacks the armor plates added in front of the driver and co drivers positions, that the Chieftain calls “sheet metal”.  It also has some late Sherman stuff, either added by the restorers, or by a depot rebuild later in the tanks life. The spot light, and ‘gun crutch’, or travel lock as normal people use were not on most small hatch shermans. Also the all around vision cupola would not be found on these tanks during WWII.

The Tom Jentz tangent. 

The Idea that the Sherman was no more reliable than any other tank, well, I don’t buy it. I like Mr Jentz’s work, and to some degree, his books helped inspire this site, since there was so little info on the web with really detailed info on the Sherman other than the Sherman Minutia site. I don’t think he really knows much about the Sherman if he thinks tanks like Panther and Tiger just needed more spare parts to be as reliable as the Sherman, it is a ridiculous idea. I do not think there was a single part on the Sherman that had a 500 kilometer life span, and that’s double the Panthers final drives.

First: The Chieftain himself has done Hatch posts on reports from the British, about how much more reliable, the M4A4 Sherman was than the Cromwell, even when both had full crews working to keep them running. both tanks were run thousands of miles, something late war German tanks could not do.

Second: In one of his own Hatches talks about the French experience with the mighty panther showed they averaged 150 kilometers per final drive set! Much less if the crew was hard on them.  There was no major automotive component including the oil, that had to be changed every 150 kilometers on any model of Sherman.

Third: This will focus on the Panther, since it was a major part of Germany’s late war armored force, and how terrible it was. This tank didn’t have just one flaw that should have disqualified it for production it had at least five. It was generally poorly reliable across all its automotive components, along with the final drive, 2500 kilometers for the motor and 1500 for the tranny were hugely optimistic and most of these tanks broke down and or were destroyed before they had to refuel. You had to take the whole drivers and co drivers compartment apart and the top of the hull off to change a transmission! Don’t get me started on the weak turret drive system that Rube Goldberg would have loved.  The  ‘wonderful’ dual torsion bar suspension and interleaved road wheels would cause any maintenance nazi to find the nearest US Line and surrender instead of working on it!

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Another thing to note, you can see the holes drilled vertically in the suspension bogies, these are the tops of the holes the bolts that hold the suspension caps on go into. They were covered up with body filler by the factory, but on most restored and old Shermans the filler is gone, and they don’t fill the holes.

Note: the odd groove in the center of the rear Hull casting, this wasn’t done on all M4A1 tanks, and may have been unique to General Steel castings.

On the problems with the R975, I have not heard of complaints about the engine being easy to blow, and would be very surprised if the throttle wasn’t governed to prevent it.  On having to crank the engine before starting, I have it on good authority, that the crew could just start the tank and run it for a few minutes every 45 minutes to an hour to avoid having to hand crank the motor.

Many of units removed the sand shields in ETO to prevent problems with mud.

The Commanders vane site is an early version bolted to a late war vane site pad. The tank has the early style gunner’s periscope.  The gunners periscope is missing the linkage going down to the gun.  The radio looks like a 528.  Note the Armored doors on all the ammo boxes and ready rack. The tank is missing a lot of interior storage, it may have been removed in preparation on shipping the tank out to it’s new owners.

I‘m no expert, but I think the Chieftain confused a .30 cal ammo bin for the 75mm ammo bin right next to his shoulder for the location of an SCR-506, I just can’t see a WWII radio fitting in the tiny box! You can see how sparsely filled the interior is, as issued the tank would be stuffed full of items to help fight it, live with it, or keep it running.  The Chieftain shows just how easy even a small hatch Sherman was to get out of,  the the Loader was still going to have some issues though.  I wish he would have tried the belly hatch out, but maybe it’s welded shut or something.

He covers the small floor hatch on the Grizzly tanks, and you get a nice shot of the early escape hatch.  They also show the generator mounted on the rear of the transmission in one of the shots, briefly.  You can also see the full turret basket’s mesh screening that separated the turret crew from the hull crew. Part of the quick fix was to cut this all out.  I suspect most of the inconsistencies in the tanks details are due to the restoration crew using the Sherman parts they could get their hands on.  Very few people would  even notice or know it had the wrong commanders hatch, or even whole turret.

A note on the tank, it belonged to a the Military Vehicle Technology Foundation, a fancy name for the collection of a man named Jacques Littlefield. He had a passion for armored vehicles of all types but really liked tanks. He restored many to full functionality, including working main guns and machine guns on some tanks.  Owning a working tank cannon is easier than you would think, and far easier than getting the paperwork approved to own machine guns in California, and Jacques Littlefield did both.  He employed a restoration crew with world class skills and did some amazing restorations, including a Panther A that was impossibly damaged, but still brought back to life.  That Panther was his crowning achievement, and he was a real mover and shaker in the international military vehicle restoration scene, seeing that tank run was one of the last things he achieved, because cancer claimed him shortly after.

The MVTF was supposed to make sure the collection of vehicles, that were a labor of love his whole life, lived on when he passed. Unfortunately the location of the MVTF, Portola California, on a large chunk of very private property, with very limited parking really presented some problem.  The collection was used often while it was there, by TV productions like Myth Busters, and was a staple for the Wargaming Staff for their productions, and occasionally opened up to groups of vets, or other interested people.  There were other difficulties with the location, and ultimately the collection was donated to the Collings Foundation.  They reportedly decided to keep 40 of the most significant vehicles and auction the rest off.  The money from the auction was going to be used to build a facility in Stowe Massachusetts, but due to zoning issues, the permits were not provided, leaving the vehicles they did keep in limbo.

I‘m sure the Collings Foundation, a really amazing Charity, they keep many rare WWII aircraft, and cars, including race cars running, has a plan for the rest of the tanks. Their website only lists the Panther in their collection, I hope that doesn’t mean they sold the rest when the museum fell through.  That’s not a criticism of the CF, they I’m sure know their business far better than I do, and they really are a top notch group of people. Just browse that site to see the airplanes they’ve gotten flying.  The only real B-24 liberator and a working F-4 Phantom are just two of the notable planes!!  If you know anything about aviation, you know just how complicated and expensive keeping an aircraft like a Phantom flying is, especially if you don’t have the resources of the U.S. Navy or Air Force backing you.

I have to say, this is one of the best Chieftain’s hatches they have done. Granted, I’m a tad biased, since it was on the Sherman, well a Grizzly made into a later model small hatch Sherman anyway, and the Chieftain really has gotten pretty good with the Sherman and its sub variants, and even has a book on US WWII TDs on the way.

 

 

 

#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 useable 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 to 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 them 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 because 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 these 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 to latish production turrets, and most 76mm turrets had a removable,  paintable from the inside, spot light 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 drivers 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 above

There was a short 10 item list of things the tank crew could do to maintain the auxiliary generator, and the final one was remove 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.

 

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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 may be 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!