Production Order T-2593: 1401 units: Serial Number 4805 / USA 3056615 through S/N 6204 / USA 3058014 *
Production Order T-3333: 4000 units: Serial Number 16555 / USA 3016861 through S/N 20554 / USA 3020860
Production Order T-3603: 2077 units: Serial Number 20555 / USA 3029082 through S/N 22631 / USA 3031158
Production Order T-3603: 21 units: Serial Number 22632 / USA 3031162 through S/N 22652 / USA 3031182

* It was suggested that Serial Number 56620 / USA 3098786 be assigned to a single M4A4 to account for the one tank delivery shortage which came about as a result of Chrysler's presenting its first M3 Medium Tank as a gift to the US Government.

The US Medium Tank was designed around an "off the shelf" 9-cylinder Wright radial aircraft engine that was widely used by the Army Air Corps and had a proven record of reliability. As the military commenced its massive build up in the early 1940s, materials priority appears to have been given to the Navy and Air Corps. Recognizing that there would be a critical shortage of aircraft engines, the Army turned to the automotive industry for alternate power plant designs. In July 1941, just as M3 Medium production was getting underway, the Ordnance Department asked the Chrysler Corporation if it could design an alternate tank power plant "in a hurry." The expedient that emerged used the "off the shelf" 6-cylinder engine from Chrysler's "Royal" line of automobiles and combined five of them into a "star" configuration. The Army found Chrysler's "stop gap" design acceptable, and in December 1941, Ordnance contracted for the installation of 109 "experimental multiple engine power plants" in the Medium Tank, M3. This configuration was given the nomenclature "M3A4" and approved for production later that same month. This was not a simple engine swap. The massive "Chrysler Multibank" required an 11-inch elongation of the existing hull. Chrysler also designed and installed heavier duty bogie units to carry the engine's greater weight. It was agreed that the cost would be "$15,000 per tank in excess of the then current unit price of the M3." Above shows what we believe was the first production M3A4. Official M3A4 production figures are given as 33 in June, 73 in July and 3 in August 1942. For a sense of the chronology, we would observe that these were immediately replaced in production by the M4A4, with the first 2 accepted in July, followed by 167 in August as the last M3s and M3A4s rolled off the line. Note the new heavy-duty bogies with trailing return roller arms. Contrary to some sources, the M3A4 was the only tank of the M3 series to have these factory installed. For convenience, we refer to them as "M4 bogies," because, as quickly as they could be produced, they replaced the older M3 type bogies, and became standard on all M4 series Shermans.








This overhead view of the pilot was taken in February 1943 shortly before the tank was converted to a mine flail. "Counting heads" suggests that the first 400 or so M4A4s did not have the "second" turret antenna bracket, or the commander's blade sight factory installed. (We've circled the future locations of these items.) The drivers' hatch handles (1) were in the "first" position, mounted towards the rear and on an angle. This can also be seen on Serial Number 4805, the first production unit. The grouser compartment holes were simply blanked off (2) rather than equipped with air scoops. Holes for a pair of fuel shut off valves (3) were located on the the rear engine deck panel, and right next to them, the lifting handles were positioned side to side. It is thought that in August 1942, the shut off holes were eliminated, the engine deck lifting handles were reoriented front to back, cast air scoops were added, and the drivers' hatch handles were installed in the "standard" position.




Japanese conquests in Asia created a rubber shortage which compelled the Ordnance Department to employ some steel track alternatives. The M4A4 pilot was used to test T49 "interrupted parallel bar" tracks in August, 1942. The photo above was marked up to show the areas in the front vulnerable to 37mm and larger armor piercing projectiles. One can see that the glacis of the M4A4 was rather elaborate, made up of 5 sections. Sections 1 and 2 were rolled armor plate, while 3, 4 and 5 were castings. The drivers' hood castings were "wide," and joined in the center to form the upper glacis. In a front photo, this glacis configuration along with Chrysler's distinctive antenna bracket casting serve to identify the type as an M4A4. It can be seen, however, to have been mislabeled an M4A2 in the information panel. Note the door stops (circled) supporting the open drivers' hatches. These were not present on the pilot when shipped, so must have been added at APG.




Chrysler President K.T. Keller was fond of recording milestones, and sending little notes with photos to Ordnance officials. Above shows the scene at the Detroit Tank Arsenal on August 3, 1942 as "CHRYSLER M4 TANKS CROWD LAST M3 OFF THE LINES." A close examination of the glossy print revealed that the M4A4 in the middle has its Serial Number 4840 chalked on, making it the 36th production unit. During the course of the M3 Lee program, Chrysler designed the pressed metal type of road wheels that can be seen, and used them throughout its production of VVSS equipped Shermans. The M4A4s shown are "still" outfitted with the same type of drive sprockets used on the M3. The M34 gun mounts are in the first configuration, with the gun shield lifting rings mounted very close to the rotor shield. While the M3 is outfitted with flat block rubber tracks, the Shermans can be seen with T48 rubber chevron tracks, which came to be the US Army's preferred type in Europe.




On August 25, 1942, Serial Number 4872, USA 3056682 was received for evaluation by the Armored Force Board at Ft. Knox, Kentucky. A report specifically mentions that it was the 67th unit built. In the "Final Report of Medium Tank, M4A4, With Chrysler Multibank Engines," dated December 15, 1942, the AFB recommended that "The Chrysler Multibank engine be considered unsatisfactory as a power plant for medium tanks and its production discontinued at the earliest possible date." The Desert Warfare Board made the same recommendation a few months later. In the event, "the earliest possible date" turned out to be September 1943, after 7500 M4A4s had been produced along with 5000 spare Multibank engines. After such a negative evaluation, Serial Number 4872 was subjected to the further indignity of ballistics tests as shown above. The M4 bogie units can be seen with the first type of track skid which had a "half round" shape. These were installed on M3A4 Lees, as well as on other early production Shermans aside from the M4A4.




The M4A4 was NOT released for overseas (combat) use by the US Army. Many served as training tanks in the US, but the majority, 7167 units, were provided to the British as Lend Lease. The first allocation, Shipping Order 3-G-1025, for 329 M4A4s was made in September 1942. The first of the tanks were shipped from New York in late November and arrived in Liverpool in mid December. 20 of them were the subject of a joint UK/US study exploring "the most satisfactory method of sealing tanks for shipment to overseas theaters of war." Chester Tank Depot in Pennsylvania used various methods to seal the tanks, and had completed the work by November 9. 15 were loaded "on deck," and 5 were loaded "under deck." Some of the deck loaded tanks were covered with "prefabricated wooden hoods" as shown above left. Upon arrival in the UK, the tanks were inspected. The study concluded with recommendations regarding standard sealing practices to be used in the future shipment of tanks. The lowest M4A4 Serial Number listed was 4830 (T-146219), and the highest was 5561 (T-146225), indicating that the tanks had been produced August through October, 1942. In the right side photos, the sand shields that can be seen were retrofitted at the request of the British. As part of the study, CTD added the so called "comb" device (arrow) to these tanks. This provided an external means of unlocking the brakes, and permitted the tanks to be manipulated into position without having to enter the vehicles, thereby ruining the shipping sealing of the driver's hatches.




Starting in January 1943, Chrysler sent technicians to both the UK and Middle East to train "artificer and driving personnel in the servicing of the power plant." T.A. Demetry one of the Chrysler techs at the Base Work Shop at El Kroub in Algeria, reported that the officers and trainees were "well satisfied with the performance of our units, and were greatly relieved upon absorbing instruction, that the power unit was not at all as complicated as they had originally imagined." In fairness to Chrysler, it must be said that, after a number of engineering changes were made, the Multibank performed well in service with the Commonwealth. At 7167 units, the M4A4 or "Sherman V" in British parlance, was the most numerous of the M4 series received by the British Empire as Lend Lease. Even after production had ceased in September, 1943, the British agreed to accept remanufactured M4A4s as part of their 1944 Lend Lease requirements, and would have taken more, had they been available, in lieu of radial engined Shermans. Credit : Dwight E. Dolan / Library and Archives Canada / PA-201361.




The combat debut of the M4A4 appears to have occurred on 10 July 1943 when C Squadron of the 12th Canadian Army Tank Regiment (Three Rivers Regt.) made an assault landing in support of the 1st Canadian Infantry Division at Pachino Bay in Sicily. The photo above depicts a later scene, and is captioned, "A British [sic] Sherman tank advancing near Catania, Sicily, 4 August 1943." The only Commonwealth unit in Sicily with M4A4s or Sherman Vs was the 1st Canadian Army Tank Brigade, which was composed of the 11th, 12th and 14th Canadian Tank Regiments. The Brigade's War Diary lists the War Department Numbers of over 240 M4A4s issued to its regiments in Scotland prior to its deployment to Sicily. The Brigade's Headquarters Squadron was issued 4, the 11th C.A.T.R. 65, the 12th 66 and the 14th 68. In addition, the 1st Canadian Tank Delivery Regiment (Elgin Regt.) was issued 41 reserve units. "Condor" appears to be T-146514. If so, the Diary has it that it was issued to the 11th Canadian Tank Regiment (Ontario Regt.). It is not possible to determine production dates if all one has to work with are British WD Numbers. However, the appearance of the tank can provide a time "window". For instance, "Condor" can be seen to have the elongated drivers' hoods that were introduced in production at Chrysler in November 1942, but it still has the M34 gun mount which was phased out before the end of February 1943. We were wondering why we could not find a single photo of a Canadian M4A4 with direct vision in Sicily or Italy. It would appear that the 240 odd M4A4s that the Canadians received had to have certain features in order to be considered "operational" for deployment to Sicily. These are listed as "single water pump engine, strengthened clutch throwout yoke, sealed and lubricated clutch throwout bearings, ventilated clutch and dust deflector." Chrysler records state that the single water pump was introduced into production at Serial Number 5804 (October 1942). The requirement for this was a must for operational status. The other item that Chrysler lists by Serial Number is "ventilated clutch" reportedly introduced at 17794 (January 1943). From this we might assume that all of the Sicily M4A4s would have to have had serial numbers of 17794 or higher, but there does seem to have been a little "wiggle room" offered in the Brigade's records regarding the clutch and dust deflector features, probably because there were not enough M4A4s with SNs above 17794 available in the UK at the time. For instance, the only WD Number we could cross reference to a US Ordnance Serial Number is T-146408 issued to the 11th Cdn. Tank Regiment. A Chester Tank Depot Shipping Ticket dated 27 Jan. 1943 lists this as Serial Number 17667, which would have been Jan. 1943 production but below the 17794 ventilated clutch threshold. Courtesy of the Imperial War Museum, Photo NA5522.




The caption of the photo above has it that the scene was filmed on 3 September 1943 at Reggio during Operation Baytown, the Eighth Army invasion of the "toe" of Italy. Based on unit histories and the date, the M4A4s would likely have been from the 14th Canadian Tank Regiment (the Calgary Regt.). According to the Official History "The Canadians in Italy", "a Calgary squadron had landed with the assault brigade [3rd Cdn. Brigade, 1st Cdn. Division] on D Day and assisted in the capture of early objectives." Chrysler transitioned to the M34A1 gun mount seen here in mid-February 1943. Note that the trailing Sherman still has the M34 gun mount. Another February addition was the "spot and signal lamp." The lamp's bracket can be seen next to the turret ventilator. Chrysler introduced the standard type of hull lifting rings seen here in January 1943. The Commonwealth retrofitted 4-inch smoke dischargers to the turrets of many of its AFVs and requested that future Sherman production include a 2-inch bomb thrower (smoke mortar) in the Sherman's turret. In the Canadian's War Diary, a late July 1943 entry has comments from Capt. W.T. Hunter regarding his visit to the 12th C.A.T.R. He noted "that only tks in HQ of Sqn have been equipped with smoke, but it has now been proved necessary that all tks carry smoke - approx 10 rds." In this case, we think Capt. Hunter was referring to 75mm White Phosphorous, since, in the following sentence he states, "They have been going into battle with 130-140 rounds and not 90 rounds as laid down." Photo courtesy of the Imperial War Museum, Photo NA6209. With thanks to Canadiana and the Canadian Research Knowledge Network for digitizing their country's WW II War Diaries and making them available online.




While the majority of M4A4s were assigned to British Lend Lease, the "French in North Africa" received 274 units that arrived in the Spring of 1943. Above shows a pair at a depot in Algeria on April 23, 1943. The stripes painted on the sides and front were in the colors of the French flag. The shipping code included "NAFUS" which we believe stood for "North Africa French - US." "SR (Sequence Requisition) 10668" indicates that this unit was one of 125 allocated and "floated" in February, 1943. The later drivers' hoods among other features suggest that the tank was produced in January 1943. Some of the many changes made to Shermans in late 1942 show up well on this tank. The gun shield with cast in lifting rings (1) can be seen to good effect. The rotor shield (2) is the later type with cast in "wing" pieces. The head lamp plug holders (3) are mounted in the later vertical position. The bogie units feature the second type of track skid (4), and the return rollers have been raised up an inch by the addition of a spacer (5). The bogie arms are the final type with the "wrench holes" (6). The Chrysler designed pressed metal or "disc type" idler (7) replaced the original welded spoke idlers in all Sherman production by the Summer of 1943. The distinctive Chrysler drive sprocket (8) replaced the M3 type sprocket around October, 1942. This tank can be seen to be equipped with the "aircraft type cowl fasteners" (circled) used to secure sand shields before the introduction of the standard or "interchangeable type" sand shield design in mid 1943.



Click on the pictures for larger size

The scene above was filmed on 14 April 1943 at "Dump #165" in Casablanca, French Morocco. It shows long lines of M4A4s and M5A1 Light Tanks awaiting processing for issue. On Vehicle Materiel (OVM) boxes can be seen stacked in the foreground. The USA Number, 3018736, of the lead M4A4 can be seen painted on in what appears to be blue drab. This tank was produced in February 1943, right at the time that Chrysler transitioned to the M34A1 gun mount, which is present on a number of the M4A4s in the background. In a "side shot," the gap (1) between the road wheels is a good recognition feature of the elongated M4A4 hull. Pierre-Olivier measured the gap and found it to be about 10 inches (25.4 cm). On other Sherman type hulls, he measured the gap at about 3 inches. Unlike our previous example, this tank has the "final" type of track skid (circled). As supplies increased, it became standard on all models to the end of VVSS production. The quarter round object on the rear deck is the exhaust deflector (2), introduced by Chrysler in January 1943. A Field Modification Kit was released in July 1943 which provided defectors for retrofit to earlier production M4A4s.




There are more surviving M4A4s, more US/Commonwealth test reports and more period photos available compared with other types of 1942/43 production Shermans. Thus, at this point, we propose to illustrate the various features of the M4A4 in greater detail. The overhead view from the M4A4 Technical Manual provides the names of various components. The Multibank was so large that there was no room for vertical fuel tanks in the front corners of the engine compartment, as on other types of Shermans. However, the elongated hull enabled the sponson fuel tanks to be enlarged to hold 80 gallons each. The height of the massive radiator required blisters on both the engine deck and the belly plate. Commonwealth users noted that the forward location of the radiator was preferred to the rear mounted, partially exposed radiators on their Lend Lease M4A2s, which were often damaged in battle.

M4A4 Hull Features

The earliest welded hull Shermans were designed with the so-called "narrow" drivers' hood castings (inset). These became standard first on M4A2s, and later on M4s. Chrysler designed the M4A4 pilot with "wide" drivers' hoods castings, and used them throughout production. Above shows a machining operation on the center assembly of the M4A4 glacis. The weld seams that joined the 3 sections stand out on the unpainted assembly. All 3 sections were castings. The lower section, part number D52417 was 62 inches wide, and included the bow machine gun fixture. Ford also used wide drivers' hoods in the manufacture of its M4A3s. However, Ford used rolled armor plate for the lower section. The bow machine gun socket used by Ford was a small casting that was welded into the plate.




In the study of Shermans, it is not unusual to encounter anomalies. The April 1943 production M4A4 shown above can be seen to have a glacis pattern in the Ford configuration. It has an armor plate lower section, with the bow machine gun casting welded in to it. The caster's logo on the MG fixture is "GAD," indicating that it was made by Ford. This is the only such example we have seen out of, say, 50 surviving M4A4s examined. Should readers come across any others, we'd be pleased to have a report.




The earliest Shermans, including the M4A4, had direct vision drivers' hoods. These were found to be ballistic weak points, and the Ordnance Department ordered them eliminated from welded hulls on August 13, 1942. Some lead time was needed to secure the new driver's hood castings. At present, our counting heads method suggests that the transition was started and completed by Chrysler in November 1942. Serial Number 5868 is the first known example we have recorded without Direct Vision, and Serial Number 5908 is the last unit recorded with Direct Vision. 5868 / USA 3057678 was designated "M4A4E1," and was used to test the installation of the 105mm gun in the Sherman. The new elongated drivers' hoods featured auxiliary periscopes in front of the drivers' hatches. The new periscopes are seen in the "up" position above. The bow machine gun dust cover fitting was a recent addition, introduced in October 1942. 5868 can be seen with the second type of track skid, pressed metal idler and the T54E2 or "Cuff Type" steel tracks.




It would appear that the original design of the M4A4 envisioned an upper rear hull plate that went straight across from sponson to sponson, as on the M3A4 Lee. We suspect that plates were cut to this pattern, but it was then decided to extend the middle section down by about 4 inches. In any case, early production M4A4s, including the pilot, can be seen with 2-piece upper rear hull plates. At present, the highest serial number we have recorded with a 2-piece plate is 5457, shown above. This tank would have been accepted in September 1942. All later examples have been noted with a single piece upper rear hull plate. We saw 5457 years ago in Brantford, Ontario. Although it is missing a lot, what is left appears to be “as built.” We believe this tank was part of an early Lend Lease shipment to the UK and was later sent to Canada. The fittings on the hull sides suggest it was once outfitted with the Canadian Indestructible Roller Device (CIRD). It is now thought to be in storage at the Canadian War Museum in Ottawa. For future reference, we would observe that SN 5457 does not show any weld scar evidence of ever having had sledge hammer fittings on the upper rear hull plate.


    

At the start of production, M4A4s featured cast hull lifting rings with rectangular bases. These "padded" lifting rings were phased out by early February 1943.


    

Above shows what we call the "standard" hull lifting rings. These castings were introduced on most Sherman types in January 1943, and were standard on the "second generation" M4 series. Our photographs show the lifting rings on Serial Number 18157, an historic French Lend Lease combat casualty on display in Dijon. This is the first M4A4 we have recorded with the standard rings. In some cases during the transition, hulls were equipped with both types. For instance, Serial Number 18223, an early February 1943 unit, has the "padded" rings on the front, and standard castings on the rear. 18223 is the last example we have recorded to date that is still outfitted with the padded type. Every unit after has been noted to have the standards on both the front and rear.


   

The M4A4 featured a distinctive "radio antenna bracket" casting. Two views are shown above. A pair of tiny drainage holes are indicated by the arrows. Chrysler produced most of its own parts, including gun mounts, power trains and suspension components. Some of these items were supplied to other builders, but as best we can tell, their antenna casting was used exclusively on the M4A4. Most surviving examples are noted to have the "C-H" (Continental-Hubbard) caster's logo in the position seen above. Pierre-Olivier examined the inside of one of these brackets and found the cast in Part Number D52416 (inset). As a matter of Sherman minutia, we would note that this is the same part number as has been observed on some antenna brackets cast by Pratt & Letchworth, although the shapes are noticeably different. In any case, the M4A4 casting was wider than most others at 16.5 inches at the base. While the brackets on some other Shermans were flush mounted, the Chrysler casting was mounted on top of the armor. It was positioned about 2 inches in from the edge of the glacis, and nearly touched the weldment of the bow gunner's hood. Small hatch, welded hull Shermans used an assortment of antenna brackets. In a front photo, the characteristic appearance of the Chrysler bracket can help identify an unknown type as an M4A4.




A pair of castings (1) with Part Number B200876 were welded on to the glacis to mount the headlamps. The M4A4 was equipped with 2 service headlamps and one driver's blackout headlamp. The blackout lamp was "hooded," and emitted "a thin flat beam of light that cannot be seen from high above, yet provides enough illumination to permit the driver to avoid most obstacles." When not in use, the headlamps were store inside, and the sockets were sealed with a plug. At first the headlamp plug holders (2) were oriented parallel to the glacis as seen above, but towards the end of 1942, they were reoriented to a vertical position, presumably to keep the plugs from falling out during travel.




The siren most commonly used on the M4A4 was the Federal Type 160 with the "V for victory" grill. The driver operated the siren by means of a foot switch located just above the clutch pedal. Note the conduit coupling (1) affixed to the glacis. Unlike some other Shermans, the siren remained mounted and unprotected on the left front fender throughout M4A4 production, including remanufacture.


   

The bow machine gun dust cover was introduced around October 1942. Above left shows the formed steel rod with snaps, referred to as the "fastener ring for canvas cover." The illustration on the right shows the dust cover in place. While the tiny fittings (arrow) were installed early on, it is thought that supplies of the "driver's windshield and hood" only became available to the Detroit Tank Arsenal at about the same time as the dust cover. For power, the windshield wiper and defroster were plugged into a utility outlet on the instrument panel. When not in use, this item was stored on a shelf above the transmission.




The crews of early production Shermans were subject to injury from falling hatches. Positive hatch lock mechanisms with equilibrator springs were reported to have been introduced at the Detroit Tank Arsenal in late April 1943 at Serial Number 20157. A modification kit was also provided for retrofit at Tank Depots and "in the field." The Firefly at Bovington is Serial Number 21188, and would have been accepted in June, 1943. This tank lacks armor applique, which leads us to think that it was one of about 1740 M4A4s shipped as built to the Commonwealth in the Summer of 1943. The locking mechanisms (1 and 2) secured the hatches when opened. The springs (3) were provided to assist the drivers in opening and closing the heavy hatches. A chain (4) held the padlocks when not in use.




Modifications came about as a result of user experience and subsequent feedback. A few surviving Commonwealth M4A4s can be seen with some simple fittings (1 and 2) that secured the open hatches. Their appearance is fairly standard, so we would assume these were installed on a number of the Lend Lease Shermans received before the introduction of the positive hatch lock modification. Our example is a December 1942 production M4A4, Serial Number 17299 which was on display for many years at the Panzermuseum in Thun, Switzerland. Crews experienced some difficulty in climbing on Shermans, so starting in late 1942, a small step (3) was factory installed to provide a little extra traction. The British actually considered adding a ladder (inset) but rejected the idea for obvious reasons. Item 4 is the fitting that held the "driver's windshield and hood."


    

All of the M4A4s were produced with power trains that were protected by 3-piece differential housings. These had been designed originally for the M3 Medium, but were carried over to the M4 series. It was intended that they be replaced by a simpler and stronger 1-piece housing which entered production in mid 1942. However, some power train manufacturers, including Chrysler, stated they could not retool for the new configuration without it creating a serious slowdown in Sherman production. Consequently, it was agreed that Chrysler would complete its run of M4A4s with the 3-piece differential housing, and switch over to the later (Part Number E8543) type 1-piece housing when it started production of the M4 Composite in August, 1943. Chrysler power trains were assembled at their Dodge Main Plant in the Hamtramck section of Detroit. Above left shows an early example. In December, 1942, Chrysler began the transition to a new configuration in which a "lip" was added to each of the cast sections in order to protect the top bolts from bullet splash damage. At the transition point, some differential housings were assembled with a combination of lip / no lip sections.




The M4A4's differential housing consists of 3 castings bolted together. In general, the right hand section is part number E4151, the middle or "carrier" piece, part number E1232, and the left hand section is part number E1231. E1232 casting marks are rarely seen on the middle piece of surviving M4A4s. The photo above shows one of the few exceptions. "Duguay-Trouin" is a monument Sherman on display in Dijon, France. She served with the 2ème Régiment de Cuirassiers, and was knocked out with the loss of 3 of her crew on September 11, 1944, during the fight to liberate the city. This M4A4 is Serial Number 18157, and was accepted in January, 1943.




As a matter of Sherman minutia, we would mention that some of the early "no lip" differential housings have been seen with alternate part numbers on the right and left hand sections. C99338 has been noted on a very few right hand sections, while D50993 has been seen more frequently on the left hand pieces. The M4A4 shown above is on display at the Kubinka Museum near Moscow, and isone of two examples we know of that has both alternate part numbers on the same differential housing. Photo courtesy of Roger Davis.


   

Chrysler started M4A4 production with the same type of drive sprocket they had used on their M3 Lees. This is shown above on the left. Counting heads suggests that they completed the transition to the rather distinctive sprocket seen on the right by October, 1942. For want of a better term, we refer to this as the "Chrysler sprocket," since they installed it exclusively throughout their remaining production of Shermans, including those with HVSS.




During the course of their M3 Lee program, Chrysler replaced the original welded spoke road wheel with a pressed metal type. Only the pressed metal was factory installed on Chrysler built Shermans with VVSS. The company transitioned to a pressed metal idler wheel in October 1942, at about the same time as the "Chrysler sprocket." Ordnance documents note that the rims of the original welded spoke idlers were so frequently damaged in service that the government mandated that they be replaced in all Sherman production with the pressed metal type in mid 1943. The Firefly at Bovington provides a good "as built" view of the pressed metal road wheels and idler. The inset shows the grease nipple, a couple of the formed spokes, and 2 of the 12 rivets that secured the body of the road wheel to the rim.




The M3 type bogies with the center mounted return rollers were overtaxed by the weight of the M3 Medium, and suffered numerous volute spring failures. The introduction of the Multibank engine, and the heavier weight of the new M4 series designs only exacerbated the problem. As a solution, Chrysler designed a larger bogie unit with heavier volute springs and a trailing return roller arm. The new bogies were released for production in January, 1942. The earliest version featured half round track skids. These were installed on all production M3A4s. Incremental changes were made to the bogies in order to increase their strength and reliability, particularly with the use of the heavier steel tracks. The early skids appear to have been replaced on the M4A4 after about 150 units. A new track skid (inset) with a larger contact area was installed starting in August and ending in early 1943.




The use of steel tracks created a friction problem with the track skid. This was remedied by the addition of a spacer (1) that elevated the return roller by about an inch. Chrysler production incorporated the spacer in early 1943. Modification kits were also provided shortly thereafter so that spacers could be retrofitted to any M3 or M4 Medium type AFV built without them. The "final" type of bogie arms (2) were also introduced in early 1943. In order to prevent the bogie arm rubbing plate bolts from working loose, they were secured at the bottom with a nut. "Wrench holes" provided access to the nuts. Chrysler appears to have introduced the "final" type of track skid (3) in February, 1943. We believe the bogie unit shown above is typical of those installed on M4A4s from March 1943 up to the end of production in September. Modelers and restorers might note the use of "cap screws" (4) to secure the bogie bracket cap. This can be compared to the nut and bolt configuration shown in the inset. Unlike other builders, Chrysler continued to use cap screws until the end of 1943. Many of the bogies supplied to Chrysler can be seen with the production date cast in. These will generally precede the tank's acceptance date by a month or two. Our example is dated 4-43.




Chrysler appears to have started M4A4 production with T48 rubber chevron tracks. Throughout production, it is noted that the ratio of rubber to steel track was approximately 50%. Unlike the US, the British preferred steel track, and noted that "Chrysler will complete the order of 6000 [T54E2] on the 15th of December [1942] and it has now been decided that...they will manufacture the T62 type...developed by this firm." We interpret this to mean that the T54E2 or "Cuff Type" would have been replaced by the T62 sometime in early 1943. These 3 types are the tracks most commonly seen in period photos of new production M4A4s. However, we would note that others, such as the T49 "cast block with interrupted parallel tread" can be seen on some of the 1610 M4A4s remanufactured for British Lend Lease from December, 1943 through October, 1944.


   

The M3A4s and a few of the earliest M4A4s were shipped with the grouser compartment holes blanked off. However, it was found that the fuel tanks of the first M4s, M4A1s and M4A4s suffered an excessive heat condition, which caused melted solder joints and other fire hazards. This was remedied by the addition of a pair grouser compartment covers with air inlet grills that permitted greater air flow as shown in the Tech Manual illustration above left. The TM also noted that starting at M4A4 Serial Number 17794, the fuel tanks were encased in insulation. Some early M4s and M4A1s were equipped with welded together "air scoops." These are thought to have been post production additions, fashioned at Tank Depots. They may have been retrofitted to a few of the earliest M4A4s, but we know of only one example - the third production M4A4 (SN 4807). The standard casting shown above right entered the pipeline at DTA in August 1942. It was made in left and right hand versions. Note that it was mounted on top on the sponson plate, not inset. The long bolt that can be seen behind the wire mesh, secured it to the hull by means of a clamp.




The M4A4 engine deck layout is shown above on Serial Number 18117, a January 1943 production unit. The rearmost section (1) was not removable but welded to the hull. Starting in January 1943, with the introduction of the exhaust deflector, the 10-pound sledgehammer was reported to have been mounted on this plate. In the instructions for installing the exhaust deflector, the implication is that the sledge hammer was originally mounted on the upper rear hull plate possibly above the track wrench, and that "Before the deflector can be installed, the sledge hammer stowage must be removed and relocated on the top rear hull plate." The inset drawing shows the "new" location. This is something of a mystery to us because, if the sledge hammer and fittings were ever mounted on the upper rear hull plates of M4A4s built before January 1943, we have never come across any period photos that show it there. It simply seems to have been missing on 1942 production M4A4s. The lifting handles (2) on the center section were oriented side to side on some of the first units but appear to have been reoriented front to back sometime during August 1942. The cast armor blister (3) protected the top of the massive radiator, and included a water filler cap. The air intake grill (4) was made up of 17 closely spaced steel rods. Curiously, the short and long bullet splash plates (5) were not always welded to the air intake grill as seen on this example.


   

Above left provides a closer view of the bullet splash plates welded to the air intake grill as seen on Serial Number 19617, an April 1943 production unit outfitted by Chrysler with an early version of HVSS. This configuration is also present on the M4A4 pilot. However, our examination of period photos and surviving M4A4s, shows that in many cases, the plates were welded to the hull. For instance, Serial Number 4807, the third production unit can be seen above right in this alternate configuration. This would have created an interchangeability issue, but we have not come across any Chrysler or Ordnance correspondence that discuss it. Our speculation is that the preference may have been to have these parts permanently welded to the hull. However, the tolerance of the turret ring appears to have varied from almost nothing to an inch, so if the splash couldn't fit on the hull itself, it was affixed to the air intake grill instead.




In this unusual view, we see an example with very little surface area available at the centerline to permit the bullet splash plates to be welded directly to the hull. Presumably, in this case the plates would have been welded to the air intake grill, but that engine deck section is long since gone from this M4A4. It can be noticed that the fire extinguisher housing (1) has been moved from its original position as indicated by the filled in holes (2). The weld seams (3 & 4) show the method of construction used to assemble the rear part of the hull's top around the turret ring. The same method was also used on 2nd Generation welded hull Shermans. This tank is Serial Number 5791 indicating October 1942 production.



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