Details of the front of the early M4A1 are shown in this image. It features the M34 gun mount, three-piece final drive and differential cover, direct vision slots for the drivers, and the rotor sight for the gunner. The latter was replaced by a simple periscope very early in the production run due to its propensity to become damaged and allow entry of bullet splash. (Picture from TM 9-731A Medium Tanks M4 and M4A1.)
This tank presents an interesting mix of early and late production features. It has the single-piece final drive and differential housing and the combination gun mount M34A1 but retains the drivers' direct vision slots. The guard on the hull front in front of the driver was to protect the siren when it was mounted, and the vertical vane sight is visible on the turret roof in front of the commander's position. This would help roughly line the turret up with a target. The two small cylinders attached to the headlight brush guards held plugs used to seal the headlight socket hole when the light assemblies were removed. When used as a command tank and with a second radio installed, the ventilator next to the assistant driver was used for the radio's antenna. This contrasts with welded hull tanks below, which have a separate antenna base.
A view of the rear deck and turret is shown here. The engine air inlet cover and its protective armor splash guard are near the turret, and the hinges for the solid rear deck engine access door are just to the rear of the air inlet cover. A pistol port was provided in the turret at the loader's station, and a lifting eye is above and behind the pistol port. This angle also allows us to see the splash guard that protected the turret ring as well as the main engine and auxiliary generator engine fuel fillers, which can be seen near the turret in the foreground and background, respectively. Stowage on the rear armor plate included the large idler adjusting wrench and the hand crank for the engine. Note the orientation of the shovel on the left side of the hull.
This rear view of an M4A1 illustrates differentiation points it shares with the M4. The rear hull plate has a shallow horseshoe shape, and the engine's air cleaners are visible at the top corners. The twin engine access doors are open in this picture, and the hole in the rear armor above the engine was for insertion of the engine's hand crank. The square muffler tailpipes are visible protruding from under the armor plate. The very bottom of the hull between the tracks is angled down as opposed to being rounded, indicating this tank was manufactured by Pressed Steel Car Company. The air inlet hoses can be seen angling down diagonally from the air cleaners toward the vehicle's center, and the black boxlike carburetor sits between them. The squat, cylindrical fuel pump is visible near the center of the rear hull opening, and has two hoses attached to it. The shorter vertical hose connects the fuel pump to the carburetor.
The rear of an early R975 C1 engine is shown here. Later engines can be readily recognized by generator being driven by the propeller shaft or transmission, and consequently not being mounted on the engine's accessory case. The engine had a 5.7:1 compression ratio; and its cylinders had a bore of 5.00" (12.7cm) and stroke of 5.50" (14.0cm), for a displacement of 973in³ (15,900cm³). (Picture from TM 9-731A Medium Tanks M4 and M4A1.)
A closer view of the assistant driver's direct vision slot is provided here. The covers were opened and closed by means of an interior handle.
This tank is fitted with square-sided air cleaners. Round ones were also manufactured.
The twin exhaust pipes reach under the hull rear into the engine compartment.
The transmission and final drive assembly has been removed from the tank. This early version had a parking brake in a housing bolted to the rear of the transmission; later, a pawl attachment to the steering levers was used. Using arms were authorized to remove and install a transmission and final drive assembly, but replacement with another assembly required authorization from ordnance personnel. The assembly weighed 8,800lb (4,000kg), and required a sling, a wrecker, and several hours of work to remove. (Picture from TM 9-731A Medium Tanks M4 and M4A1.)
Components of the stabilizer system are shown here. A. Flexible shaft. B. Clamp. C. Mounting screw. D. Oil reservoir. E. Filler plug. F. Sight glass. G. Drain plug. H. Top cover screw. J. Control box. K. Stiffness rheostat. L. Pilot light. M. Recoil rheostat. (Picture from TM 9-731A Medium Tanks M4 and M4A1.)
More components of the stabilizer system are shown here. A. End cover. B. Gear box. C. Spring oiler. D. Multi-prong plug. E. Gear box clamp. F. Dust shield. G. Gyro control. H. Oil gear traverse. J. Stabilizer switch. K. Firing switch. L. Turret switch. M. Westinghouse motor. N. Oil pump. (Picture from TM 9-731A Medium Tanks M4 and M4A1.)
Stabilizers were built with mono- and double-gyrostabilizers. The double-gyro control tended to stay vertical, and when moved from vertical it created forces to instantly return it to vertical. On the other hand, mono-gyro control units did not have a precise reference point, and therefore sometimes would not return to their exact starting point. Mono-gyro controls could slope up to 60° from vertical when influenced by the balance and friction of the gun mount, temperature, and oil pump characteristics. (Picture from TM 9-731A Medium Tanks M4 and M4A1.)
The rear corners of the hull featured an air scoop protected by a mesh screen.
Early production tanks manufactured by the Pressed Steel Car Company featured riveted lower hulls. These rivets can be seen between the suspension bogies.
The eccentric adjustment mechanism for the idler wheel is shown here. The large wrench stowed on the outside of the tank was used to turn the large nut on the inboard side of the assembly, extending or retracting the idler wheel to ensure proper track tension. The outer two large bolts on the bottom of the split idler shaft housing are clamping bolts, while the center one is the spreader bolt. Loosening the clamping bolts and driving the spreader bolt into the housing opens the housing, allowing the idler mechanism to be loosened or tightened.
The rear engine compartment top plate is missing on this tank, providing us with a top-down view of a mounted engine. The large exhaust pipes in the center of the image emerge from the exhaust collector rings on each side of the engine, and the pot-like crankcase breather can be seen perched atop the engine between the exhaust pipes. The right-hand exhaust collector ring serviced four cylinders, while the left-hand unit took care of the other five. The pipes outside the exhaust pipes chute air from the intake behind the turret to the air cleaners mounted on the hull rear. The right-hand primary booster coil can be seen below the right-side exhaust pipe, and has shielded wires attaching it to the right-hand magneto. Shielded wires on the opposite side of the engine reveal the presence of the left-hand booster coil, though it is hidden by this same exhaust pipe. The exhaust pipe for the auxiliary generator can just be seen between the left-hand main engine exhaust pipe and air inlet pipe near the top of the image. (Picture courtesy Pete Sheppard, via TankNet.)
This tank is fitted with spaced-out suspension that allowed extended track end connectors to be installed on both the outer and inner sides of the track. Spacers were welded to the hull that moved the tank's suspension outwards by 4.5" (11cm), which allowed the 3.5625" (9.0479cm) end connectors to clear the tank hull. With both sets of extended end connectors installed, the track width was increased to 23.6875" (60.1663cm), and ground pressure decreased to ~10psi (.702 kg/cm²). In August 1944, pilots of tanks with these suspension spacers were designated with an -E9 suffix (e.g., M4A1E9), and production of 1000 kits each for field modification and for application to tanks returned for rebuilding was authorized in early 1945. The kits and end connectors added 1360lb (617kg) to the tanks, and installation required 326 man-hours and at least two skilled welders. This rear view shows to good effect the extra track width provided by the extended end connectors. Note the wider fenders that came equipped with stanchions that attached to the side of the hull. Between the engine air cleaners is a late-production exhaust deflector, more details of which are provided here. A folding blanket rack is mounted on the hull rear plate above the exhaust deflector. (Photo by Richard S. Eshleman.)
This tank is fitted with the single, dry pin Canadian Dry Pin (CDP) track that was mounted on some cruiser tanks Grizzly I built at the Montreal Locomotive Works. Note that, in contrast to the rubber bushed live track that was mounted on US tanks, the CDP track is very slack across the return run.
The CDP track had a pitch of 4.6" (12cm), necessitating a different drive sprocket with 17 teeth. Due to this size difference, 102-103 shoes per track were installed.
Further details of the track are provided here. The CDP track was 15.5" (39.4cm) wide and made from cast steel. The shorter track pitch and narrower track shoes would both lead to a marginally higher ground pressure for the tank.
Grizzlies were fitted with British-style stowage boxes on the turret rear. The box itself is absent from this vehicle, but the mounting brackets remain on the turret bustle. Also note the channel at the end of the rear deck just above the hole for the engine's hand crank; this was characteristic of early hulls cast by General Steel.
The applique armor panels attached to cast hull tanks had to be cut into pieces and individually welded to the hull, and this view shows why: Attaching the large flat plates to the contoured surface would otherwise have been problematic.
Tool stowage was altered on Canadian-produced tanks. Compared to the vehicles above, the strap for the shovel blade was at the front, and the track tension adjusting wrench and sledgehammer were stowed above the shovel instead of on the hull rear. Additional footman loops are welded to the hull left side as well.
The assistant driver in the Grizzly was given an additional hatch in order to attach the indigenous Snake mine-clearing line charge. In this image, the joint for the right and center sections of the final drive and differential cover can be seen at the top center, and the large hull escape hatch is visible in the center of this image. The smaller hatch for the Snake attachment is forward of the hull escape hatch, right next to the attachment point of the forward suspension bogie on the left of the picture.
The smaller hatch is the focus of this image. The hatch featured two hinges to the front, which were each attached to the hull with three rivets in a triangular orientation. The line of bolts running across the top of the image secured the final drive and differential cover.
This is a very early M4A2 produced by the Fisher Tank Arsenal. It retains the early suspension bogies with the top-mounted return roller, and the twin driver's machine guns are mounted. These were eliminated before the first M4A2 was accepted, but production had already begun at Fisher before the change. The smooth rubber T51 tracks are readily evident on this tank, as is the bolted three-piece final drive and differential housing at the front of the hull. This M4A2 has the 56° glacis with early drivers' direct vision slots, and weld lines can be made out around the individual plates. There is an antenna base next to the assistant driver's position above the lifting eye, and the siren is mounted on the driver's fender. The tank's coaxial machine gun emerges from the aperture to the 75mm gun's left, and the M34 gun mount did not feature a gunner's telescope. Interestingly, in contrast to the coaxial and driver's machine guns, the bow machine gun is absent. (Picture taken June 1942 by Alfred T. Palmer; available from the Library of Congress.)
The layout of the rear of the M4A2 is shown here. The rear plate reaches below the sponsons, and bolts form a "T" on the rear plate. The exhaust deflector is below the rear plate between the idler wheels, and the track adjusting wrench is stowed on the rear plate. (Picture from TM 9-731B Medium Tank M4A2.)
The M4A2's rear deck fixtures are illustrated here. Note the engine grille doors are approximately as wide as the turret bustle; similar grilles on the M4A3 ran all the way to the sponsons. Later in production, a seventh cover similar to the six filler cap covers was added directly behind the engine grille doors. This protected an engine oil gauge added after improvements to the engine lubrication system that reduced particulate levels and increased cooling. This tank's registration number in the previous picture reveals that it was produced by Fisher Tank Arsenal, and their welded splash guard bolted on to protect the rear of the turret race indicates that this tank has the direct vision slots. Also note the different grouser compartment covers from the M4A1 above. (Picture from TM 9-731B Medium Tank M4A2.)
A cross-sectional view of the M4A2's is provided in this image. (Picture from TM 9-731B Medium Tank M4A2.)
Ammunition stowage is detailed here. The need for the wet ammunition restowage that premiered in 1944 can be seen, as there was plentiful main gun ammunition behind the vulnerable sponson armor. (Picture from TM 9-731B Medium Tank M4A2.)
The Sherman's gyrostabilizer control and gear boxes are shown here. The stabilizer was to be used only when the tank was in motion, and to protect the batteries the auxiliary generator was to be run while the stabilizer or power traversing mechanisms were being used. The tank's speed was to be held as constant as possible and the engine was to be run at full governed speed when the stabilizer was on. Lower gears were to be used if lower speeds were desired while still running the engine at its maximum rpm. (Picture from TM 9-731B Medium Tank M4A2.)
The gyrostabilizer connected to the gun mount via this hydraulic cylinder. (Picture from TM 9-731B Medium Tank M4A2.)
This early-production M4A3 features the drivers' direct vision slots and lacks the applique armor later added over the hull ammunition racks and the gunner's controls on the turret. It also has the gun mount M34 which used a periscopic primary sight; since no telescope was fitted, the armor flap on the right side of the M34A1's rotor shield is absent.
Since the gun mount M34 did not feature a telescope, the right side of its gun shield was solid.
The opposite side of the gun mount M34 is shown, and the coaxial machine gun slot can be seen. If the coaxial machine gun armor was fitted, it would attach to the machine gun barrel itself. Since the machine gun is missing on this tank, the armor is not present even if it had been originally mounted. Weld marks across the glacis and between the drivers' hoods show how the 56° glacis was built up from several plates.
The armored cover for the assistant driver's direct vision slot is raised on this example.
The rear of this tank illustrates how the rear armor plate comes below the sponson line (below the attachment points for the sandshields), and the exhaust deflector is fitted below the rear overhang. Stowage brackets for the .50cal machine gun are present on the turret bustle. A folding blanket rack for the crew is mounted on the rear hull plate, and brackets for stowing cleaning rods for the 75mm gun are visible on its underside. This tank has been modified in a post-World War II rebuild program to incorporate later features, including the torsion bars attached to the engine grilles on the rear deck. These grille doors would have had simple hinges originally.
The engine exhaust deflector is highlighted in this image. This type of was of sheet metal and was hinged to allow access underneath. A handle was designed into the deflector to ease raising the deflector. Further details of the blanket rack, including hinges and a better look at the gun cleaning rod stowage brackets, can also be seen.
The left-side exhaust pipe for the main engine is shown here. Note that the collar is shaped to clear the towing shackle below on the hull. The small pipe to the left of the engine exhaust is the exhaust for the auxiliary generator.
The shape of the engine exhaust pipes can be better seen on this machine with the deflector out of the way.
Details of the commander's cupola and .50cal machine gun mount and stowage brackets are revealed in this image. The earlier commander's split hatch had an integral mount for the .50cal machine gun, but when the vision cupola was installed a hinged mount was added to the roof which was able to be folded down when not in use. An antenna is present in the left antenna mount. There is another smaller square antenna mount visible on the right side of the turret bustle. This mount would be in use on British tanks, as their No. 19 radio used two antennas.
The applique armor welded to the front of the turret is highlighted in this picture. The turret armor was reduced to 2" (5.1cm) at this spot to make room for the gunner's controls, and these applique plates brought the thickness back to a nominal 3" (7.6cm).
Another angle of the turret applique is shown here. Note that the plate is actually two pieces of armor welded together due to the curvature of the turret.
This 56° glacis tank was built with drivers' hoods with periscopes instead of direct vision slots. Applique armor was added to the hoods in a manner similar to that of the hull sides and turret. The mount for attaching a canvas dust cover around the hull machine gun had to be re-welded to the applique plate. This tank is also fitted with a gun travel lock.
The locations of the extra set of periscopes for the drivers is better illustrated in this image. Also visible are the spring and hold open catches for the driver's hatch door. The armor pieces protecting the sides of the base of the 75mm gun were not seen on the earliest M34 rotor shields.
Both periscopes can be seen in this example, as well as the hatch's internal locking mechanism in the upper left corner.
This late M34 mount was modified to accept the telescopic sight also found in the M34A1 mount, and a slot was cut into the gun shield to accommodate it. Additional armor was welded to the right side of the rotor shield to protect the telescope, but the left side of the mount was unmodified. The right side gun shield lifting eye was deleted in favor of a threaded hole. The armor for the coaxial machine gun is missing on this tank.
The front applique armor plates were 1.5" (3.8cm) thick, and welded at the top and bottom. The hull antenna mount and a lifting hook are in the foreground.
This more complex vane sight replaced the earlier simple device seen on the M4A1 above.
The gunner's periscope was initially protected only by sheet metal, but an armored cover was designed and implemented.
The right side of the Ford GAA engine is shown here. (Picture from TM 9-759 Medium Tank M4A3.)
This sectionalized view shows the interior arrangement of the tank. Note the propellor shaft running underneath the turret from the engine to the front-mounted transmission. This feature, common to all Shermans, had much to do with their height, especially since tanks with taller radial engines were designed first. (Picture from TM 9-759 Medium Tank M4A3.)
This cutaway turret shows the location of the 2" smoke mortar as well as the loader's periscope. The coaxial machine gun is obvious, and the radio is visible in the rear of the turret. A submachine gun is stowed above the radio.
The bottom of the gunner's seat is visible in this picture, along with the turret ring. The underside of the white-painted gearbox for the hydraulic traversing mechanism can be seen along the turret race, with the rusty shifter lever attached to its underside. The green box houses the turret master switch and reset buttons, and the hydraulic traverse control handle can be seen above the coiled yellow cord.
The final drive and differential cover has been cut away in this view. The steering brake can be seen outboard of the controlled differential gearing.
The right-hand final drive is shown here. The splined shaft would connect to the controlled differential, and the drive sprocket would attach to the hub at the opposite end.
The suspension bogie on this early tank features a straight return roller arm. Steel tracks could cause severe wear to the track skids, so the return rollers were raised to help compensate. Until raised return roller arms made it into production, the return roller itself was raised a bit by the spacer placed between the roller and the mounting arm, as seen here.
This picture illustrates the difference in the turret rear for tanks with the 56° glacis compared to later-production tanks with the 47° glacis and larger drivers' hatches. The turret in the background belongs to a 56°-glacis M4, and the radio bustle can be seen sloping downward from the roof. The tank in the foreground is an M4(105) with the 47° glacis, and its radio bustle protrudes at a much more horizontal angle which provides more clearance from the hull. This change was due to the taller hinges associated with the large drivers' hatches.
This tank is also fitted with the spaced out suspension seen on the M4A1E9 above. This is a later-production M4 produced by the Detroit Tank Arsenal, as evidenced by the composite cast/welded hull. The border between the cast and welded portion of the hull is marked by a large weld, and the applique armor on this side follows the weld line.
The guard for the siren is next to that for the left headlight cluster, and the ventilators are visible at the top corners of the front hull outboard of the drivers' hatches. The Audi TT RS parked beside the tank provides some scale.
The effect of adding extended end connectors to both sides of the track are highlighted in this closer view.
The spacer between the hull and suspension bogie is shown here. The four holes in the front of the suspension bracket are for attaching the return roller; the brackets themselves could be used on either side of the tank.
The idler spacer attachment is seen in this image.
The drive sprocket also had to be pushed out to make room for the inner end connectors.
Sharing an engine with the M4A1, the exhaust setup was quite similar. The auxiliary engine exhaust can be seen on the left, and one of the air cleaners is on the right.
The rear engine compartment top plate was hinged towards the front of the tank, and the air inlet cover and its protective splash guard are directly behind the turret. Fuel filler covers are outboard of the engine air intake.
A closer look at the air intake is provided in this image. Both it and the turret ring were provided with splash guards. The cover for the fuel filler cap is missing in the lower right of the picture, revealing the armor thickness. A ventilator housing can be seen inside the turret ring splash guard on the right side of the picture.
The hull applique armor on the assistant driver's side was cut and welded to better conform to the cast front hull.
This is also a late-production M4 from the Detroit Tank Arsenal, shown by the composite cast/welded hull. This example lacks applique armor, and the vane sight and spotlight attachment are visible on top of the turret. (Picture from SNL G-104, Vol. 6, 11, and 14.)
This rear view shows the engine access doors in the lower hull rear and the general shape of the upper rear armor. Compared to the cast M4A1 above, the rear plate is angled instead of curved. (Picture from SNL G-104, Vol. 6, 11, and 14.)
The tank is seen from above here; note that this tank does not have direct vision slots, despite the confusing nomenclature list that follows. A. Towing cable. B. Left fuel tank filler cap covers. C. Auxiliary generator fuel tank filler cap cover. D. Periscope. E. Turret hatch doors. F. Turret. G. Ventilator. H. Driver's door. I. Direct vision door. J. 75-mm. gun. K. Assistant driver's door. L. Indirect sighting device. M. Crowbar. N. Mattock handle. O. Right fuel tank filler cap covers. P. Shovel. Q. Mattock. R. Axe. S. Fuel tank compartment air inlet cover. T. Engine compartment cover, rear. U. Engine compartment air inlet grille cover. V. Radio antenna bracket. (Picture from TM 9-731A Medium Tanks M4 and M4A1.)
A cross-section of the early exhaust deflector fitted to radial-engined tanks is sketched above. The exhaust gases blew down onto the curved metal and then outward and upward, and this reduced the large dust signature that was otherwise raised. The deflector was hinged and could be swung upwards under the hull rear plate, as shown in the ghosted image. The exhaust pipe for the auxiliary generator engine is depicted by the flexible hose snaking under the hull rear plate. (Picture from SNL G-104, Vol. 6, 11, and 14.)
The second type of exhaust deflector found on radial-engined tanks is seen here. It was also hinged, and could be raised and attached to the outside of the hull rear plate, as shown in the dotted image on the left. The right-hand sketch shows how the air cleaners were still visible on each side of the deflector. The auxiliary generator exhaust pipe is shown between the air cleaner and main engine exhaust pipe. (Picture from SNL G-104, Vol. 6, 11, and 14.)
The driver's position of an early-production tank is shown here. (Picture from TM 9-731A Medium Tanks M4 and M4A1.)
A late-production driver's position can be contrasted with the early one. Differences included the parking brake pedal at the base of the steering levers, siren switch being hand operated instead of foot operated, instrument panel design, compass location (mounted to the hull roof over the transmission in late-production tanks), primer pump moved from the instrument panel to in front of the driver, and a foot guard being installed on the clutch pedal. (Picture from TM 9-731A Medium Tanks M4 and M4A1.)
The Westinghouse electric turret traverse system is shown here. When activated, the turret rotated proportionally to the speed with which the traverse handwheel was turned. In manual mode, the handwheel had a 1:463 ratio to the turret ring, and when power traverse was engaged the power-assisted ratio was 1:100. The gunner and commander were each provided with a high-speed switch that sent full power to the motor and enabled the turret to complete a rotation in 15 seconds. This could be used to quickly change targets. Pushing the switch to the right traversed the turret in that direction, and vice-versa. The gunner's switch was on top of his control box, and the commander's was on the turret roof to the left front of his hatch. (Picture from TM 9-731A Medium Tanks M4 and M4A1.)
The high-speed switch in the Westinghouse traverse system was later replaced with a high-speed control handle that allowed variation in the fast turret traverse up to the maximum speed. The traverse handwheel is omitted on this drawing for clarity, but its mounting socket is seen next to the change lever. (Picture from Sherman Tanks 75 mm. M3 Gun and Coaxial .30" Browning Machine Gun Armament Training Pamphlet.)
Details of an early turret are shown here. This turret lacks the loader's hatch. (Picture from TM 9-1750K Ordnance Maintenance--Tracks and Suspension, Turret and Hull for Medium Tank M4 and Modifications.)
Parts of the suspension bogie are labeled in this image. (Picture from TM 9-1750K Ordnance Maintenance--Tracks and Suspension, Turret and Hull for Medium Tank M4 and Modifications.)
Compared to other Shermans, the bogies on the M4A4 were spaced farther apart to compensate for the extended hull necessitated by the large A57 engine. This tank is fitted with the early gun mount M34 without armor protection for the coaxial MG. (Picture from SNL G-104, Vol. IX.)
Though showing considerable signs of abuse, the larger space between the suspension bogies is shown here to good effect.
The need for the bulges in the engine compartment deck and floor can be seen in this sectional view; the engine's fan and radiators would not have otherwise fit. Note that the hull has not been lengthened to scale in this image. The difference can be contrasted with the picture above. (Picture from SNL G-104, Vol. IX.)
Distinctive features of the rear of the M4A4 Sherman can be seen here. Immediately apparent is the radiator bulge in the deck. The M4A4 was built with two engine access doors in the rear hull. The radio bustle is apparent in the turret rear, along with antenna mounts in the roof of the turret, and a pistol port is visible on the turret's left side. (Picture from SNL G-104, Vol. IX.)
Details of the top of the tank, including tool stowage, is shown here. Note the gun mount M34. (Picture from TM 9-754 Medium Tank M4A4.)
The assistant driver had no aiming device on his machine gun besides walking fire onto a target using tracers or impacts. Note that this tank was fitted with direct vision slots for the drivers; the control is mounted to its right. (Picture from TM 9-754 Medium Tank M4A4.)
This image shows one of the first 1303 multibank A57 engines manufactured for the M4A4. These, along with all of the engines for the M3A4 Lee, had a water pump for each engine. These engines had the generator mounted on engine 2 and driven by that engine's water pump belt. The fuel pump was found on the distributor end of the crankcase and was driven by the accessory shaft. The first 3210 M4A4 engines had thermostats in the cooling system mounted in each engine's water outlet adapter. The rest of the engines had a bypass-type thermostat mounted in the cylinder head adapter of engine 1 and the radiator inlet adapter of engines 2-5. The first 3411 M4A4 engines used a fully-enclosed clutch, followed by a ventilated clutch in later engines.
The legend of this image is as follows: A. Cleaner, air, crankcase ventilator, assembly. B. Pump, water, assembly (no. 1 engine). C. Plate, engine lifter and step, assembly. D. Filter, oil, with clamp, assembly. E. Tube, water pump air relief (engine no. 1 to no. 5). F. Coil, ignition, assembly (no. 5 engine). G. Pipe, exhaust (nos. 4 and 5 engines). H. Tube, fuel pump to branch connection, assembly (for nos. 4 and 5 carburetors). I. Connection, water pump air relief. J. Tube, fuel pump to no. 1 carburetor, assembly. K. Pump, water, assembly (no. 5 engine). L. Distributor, ignition, assembly (no. 5 engine). M. Plate, serial number, engine. N. Coil, ignition, assembly (no. 3 engine). O. Tube, fuel pump to branch connection, assembly (for nos. 2 and 3 carburetors). P. Tube, water pump air relief (engine no. 4 to no. 5). Q. Tube, radiator outlet, assembly (nos. 4 and 5 engines). R. Coil, ignition, assembly (no. 4 engine). S. Pump, water, assembly (no. 4 engine). T. Distributor, ignition, assembly (no. 4 engine). U. Pump, fuel, assembly. V. Support, engine, rear. W. Pan, oil, assembly. X. Plug, drain, oil pan. Y. Distributor, ignition, assembly (no. 3 engine). Z. Pump, water, assembly (no. 3 engine). AA. Tube, radiator outlet, assembly (nos. 2 and 3 engines). BB. Cock, drain, cylinder water jacket, assembly. CC. Distributor, ignition, assembly (no. 2 engine). DD. Distributor, ignition, assembly (no. 1 engine). EE. Tube, water pump air relief (engine no. 2 to no. 3). FF. Pump, water, assembly (no. 2 engine). GG. Connection, radiator outlet tube, assembly (no. 1 engine). HH. Gear, reduction, tachometer drive, assembly. II. Generator, assembly. JJ. Coil, ignition, assembly (no. 1 engine). KK. Pipe, exhaust (nos. 1, 2, and 3 engines). LL. Tube, water pump air relief (engine no. 1 to no. 2). (Picture from TM 9-1750F Ordnance Maintenance--Power Unit for Medium Tanks M3A4 and M4A4.)
Later A57 engines used a single water pump, which simplified maintenance. In tanks with these engines, the generator was found in the fighting compartment and driven by the propeller shaft via a belt. The fuel pump was on the distributor end of engine no. 4 and driven by the camshaft.
The legend of this image is as follows: A. Cock, drain, engine cylinder water jacket, assembly (engine no. 1). B. Block, engine cylinder (engine no. 1). C. Harness, engine wiring, assembly. D. Tube, outlet, oil filter assembly. E. Unit, sending, engine oil pressure warning indicator. F. Cock, drain, engine cylinder water jacket, assembly (engine no. 5). G. Tube, outlet, radiator, right, assembly. H. Tube, outlet, water pump, assembly (engine no. 4). I. Pump, fuel, assembly. J. Cock, drain, engine cylinder water jacket, assembly (engine no. 4). K. Support, engine, rear. L. Plug, drain, oil pan. M. Plate, name, engine serial number. N. Cock, drain, engine cylinder water jacket, assembly (engine no. 3). O. Tube, outlet, water pump, assembly (engine no. 3). P. Tube, outlet, radiator, left, assembly. Q. Cock, drain, engine cylinder water jacket, assembly (engine no. 2). R. Tube, outlet, water pump, assembly (engine no. 2). S. Pump, water, assembly. T. Fitting, grease, water pump body. U. Tube, outlet, water pump, assembly (engine no. 5). V. Connection, main branch, fuel pump to carburetor tube, assembly. W. Tube, overflow, radiator, assembly. X. Tube, outlet, water pump, assembly (engine no. 1). (Picture from TM 9-1750F Ordnance Maintenance--Power Unit for Medium Tanks M3A4 and M4A4.)
This top-down view of the Westinghouse turret traverse system shows why it was necessary to add applique armor outside the gunner's position. A section of the inside turret wall was ground away to make room for the his controls for all three traverse systems. (Picture from SNL G-104, Vol. IX.)
The increased space between the bogies on this M4A6 is similar to that found on the M4A4. The weld line showing where the cast upper front hull was attached to the rest of the hull is apparent as it slopes downward and forward from behind the drivers' hatches, just in front of the applique armor welded over the sponson ammunition rack. The bulge on the rear deck can be seen just behind the guard for the fuel filler cap. The 75mm gun on this tank is secured in the travel lock. (Picture from Development of Armored Vehicles, volume 1: Tanks.)
The gunner's controls with the Oilgear hydraulic turret traversing system are shown here. The commander was eventually provided with a master control handle that allowed him to traverse the turret and override the gunner's control if necessary. (Picture from TM 9-756 Medium Tank M4A6.)
The front of the RD-1820 is seen here. The engine could run on fuel ranging from diesel to low octane gasoline; it was governed under full load at 2000rpm; and its cylinders' bore was 6.125" (15.58cm) and stroke was 6.875" (17.46cm), for a displacement of 1,823in³ (29,870cm³). It had a 15.5:1 compression ratio; weighed 3,900lb (1,800kg) without its air cleaners, fuel filter, and oil filter; was 55" (140cm) in diameter; and was 70.16" (178.2cm) long with its starters and air inlet elbows. (Picture from TM 9-1756A Ordnance Maintenance--Ordnance Engine Model RD-1820 (Caterpillar).)
Details of the rear of the engine are shown in this image. (Picture from TM 9-1756A Ordnance Maintenance--Ordnance Engine Model RD-1820 (Caterpillar).)
The engine is seen here installed in the hull. (Picture from TM 9-756 Medium Tank M4A6.)
The transmission and final drive assembly is shown here removed from the vehicle. Note the lack of parking brake lever compared to the assembly above; on later vehicles the parking brake function was given instead to the steering levers. (Picture from TM 9-756 Medium Tank M4A6.)
When comparing 76mm gun tanks with the 75mm gun tanks, the new turret borrowed from the medium tank T23 is an obvious difference. A new gun travel lock was also needed for the longer weapon, and it is folded on the glacis here. The stowage brackets for the .50cal machine gun can be glimpsed on the turret bustle. This tank is fitted with the tank mounting bulldozer M1, the blade of which was 48" (120cm) high and 124" (315cm) wide. The setup added 7100lb (3200kg) to the tank's weight. (Picture from TM 9-719 Tank Mounting Bulldozer M1 and M1A1.)
The top of a tank with a commander's vision cupola and loader's split hatch is diagrammed here. A. Periscope holder. B. Assistant driver's hatch door. C. Periscope. D. Ventilator. E. Sighting device. F. Commander's vision cupola. G. Direct vision block. H. Periscope. I. Cupola escape door. J. Right fuel tank filler cap cover. K. Crow bar. L. Mattock handle. M. Mattock. N. Ax. O. Grouser compartment scoop. P. Sledge hammer. Q. Engine compartment cover, rear. R. Track adjusting wrench. S. Engine oil tank filler cap cover. T. Shovel. U. Left fuel tank filler cap cover. V. Auxiliary generator fuel tank filler cap cover. W. Towing cable. X. Turret hatch doors. Y. Turret. Z. Driver's hatch door. AA. 76-mm gun. AB. Gun traveling lock. AC. .30 cal. gun. (Picture from TM 9-731AA Medium Tank M4 (105-mm Howitzer) and Medium Tank M4A1 (76-mm Gun).)
The tank commander's hydraulic traverse control handle for the Oilgear traverse system would override inputs by the gunner, allowing the commander to take control of the turret at any time. A button was pressed on top, then the handle was pushed forward to traverse counterclockwise or pulled backwards to traverse clockwise. (Picture from TM 9-731AA Medium Tank M4 (105-mm Howitzer) and Medium Tank M4A1 (76-mm Gun).)
This is one of the 1465 M4A1(76)Ws fitted with horizontal volute spring suspension, and it is wearing single-pin steel T66 tracks. Spare track shoes are stowed on the fenders. The shock absorbers are mounted above the bogies horizontally.
Further details of the T66 track are shown here. Single-pin track was relatively rare on American tanks at this time.
The rear face of the track was steel as well, which was more wearing on suspension components versus rubber or rubber-backed track. The horizontal volute spring of the forward bogie is visible in this image as well.
Both types of return roller can be seen in this picture. There were three of the single rollers supporting only the inner run of the track at the front, center, and rear of the hull, and dual return rollers were placed between the single models.
The procedure for adjusting the track tension with HVSS was the same for VVSS, as described above.
A filler cap for lubricating oil was added in the rear deck plate on later-production radial-engined tanks. The cylindrical socket for holding the idler wheel adjusting wrench has been moved to the top of the rear deck and can be seen at the bottom of the picture. The turret on this tank is equipped with a ventilator at the rear, and its armored exhaust port can be seen on the turret bustle; the stowage pintle for the .50cal machine gun is welded to this port. Early 76mm gun turrets did not feature this ventilator since the medium tank T23 for which the turret was designed had a stronger ventilator between the drivers.
The drivers' larger hatches and the two periscopes for each man can be seen in this image. A ventilator was mounted between them; a cover for the ventilator was not present on early vehicles.
The shallow horseshoe shape originally found in the rear armor eventually was leveled out to improve protection for the air cleaners; triangular armor pieces were also added at the upper corners. The turret ventilator can better be seen in this image, as well as the .50cal MG stowage brackets. The top portion of the MG mounting post is visible on the turret roof.
The contours of the welded and cast hull tanks can be easily contrasted in this picture.
The longer final drive covers for tanks with HVSS can be contrasted to the shorter cover on the removed transmission and final drive assembly above. (Picture from SNL G-207.)
The wet ammunition stowage rendered the applique armor applied over the ammunition racks of earlier tanks redundant. The second set of drivers' periscopes that replaced the earlier direct vision slots are also visible from this angle. (Picture from SNL G-104, Vol. 15.)
Stowage on the rear of the tank includes track shoes on each side of the hull and gun cleaning equipment on the underside of the crew's blanket rack. The turret rear can also be contrasted with that of earlier 75mm gun tanks. The larger hatches built into the 47° glacis tanks required raising the turret bustle a few inches to allow for clearance. This can be seen here along with the less severe slope of the top of the turret bustle, especially when the antenna mounts are compared. (Picture from SNL G-104, Vol. 15.)
Compared with the 75mm gun tanks, the howitzer travel lock is mounted lower on the upper hull front plate, which can be easily seen when its location vis-à-vis the bow machine gun is compared with the gun travel lock of the 75mm gun tank above. An attachment for a dust cover can be seen ringing the howitzer shield and the turret front. The howitzer shield features lifting hooks at the top and large screws at the base of the ordnance. The drivers' hatches with their periscopes can be seen, and their increased width compared to earlier vehicles made exiting easier. The hull ventilator between the drivers is fitted with a cover.
Compared to 75mm gun tanks, the 105mm howitzer shield was thicker and protruded a larger distance from the turret front. The turret itself was similar to the 75mm gun turret found on tanks with the 47° glacis. The tall hinge associated with the large drivers' hatches is apparent at the driver's station; the turret bustle was raised in order to clear these hinges. Note the double-ended bolts in the final drive and differential housing in front of the howitzer travel lock; these were part of the equipment to attach the tank mounting bulldozer M1.
The large aperture in the howitzer shield's right side was for the gunner's sighting telescope, while the opening in the left of the shield was for the coaxial .30cal machine gun.
The rear hull plate has been extended to eliminate the shallow horseshoe shape in order to further protect the engine air cleaners, and supplementary armor has been installed around the air cleaners. The exhaust pipe for the auxiliary generator engine can be seen just outboard of the left air cleaner armor. A difference in howitzer turrets versus 75mm gun turrets was an additional ventilator at the rear, the opening for which can be seen between the commander's cupola and the antenna mount. The base of the .50cal machine gun mounting post was therefore designed to fit over top of this ventilator. Note that on this machine the right-hand air scoop over the track grouser compartment is missing.
A more detailed shot of the elevated folding .50cal machine gun mount is provided here.
The interior of the open grouser compartment is shown here. The thickness of the hull roof armor can be seen as well.
The late-production radial engine deck is illustrated here, with an additional filler cap for lubricating oil on the central deck plate. Fuel fillers are on the sloping sides on either side of the shrouded air intake, and a bracket for aiming stakes and howitzer cleaning rods is below the hull lifting eye.
The oil filler cap can be better seen from this angle, and the lip of the base of the .50cal machine gun mounting post can just be made out above the turret ventilator.
The contours of the sharp-nosed single-piece final drive and differential cover are shown here.
The shorter, thicker barrel on this tank's ordnance, the lifting eyes on the upper lip of the ordnance shield, the large screws evenly spaced around the ordnance, and the location of the travel lock indicate that it is a 105mm howitzer tank. (Picture from SNL G-104, Vol. 6, 11, and 14.)
The top of the tank is shown here. A. Periscope. B. Assistant driver's hatch door. C. Sighting device. D. Turret hatch doors. E. Periscope. F. Mattock handle. G. Crowbar. H. Ventilator. I. Right fuel tank filler cap cover. J. Shovel. K. Mattock. L. Ax. M. Grouser compartment scoop. N. Sledge hammer. O. Engine compartment cover, rear. P. Engine compartment air inlet grille cover. Q. Track adjusting wrench. R. Engine oil tank filler cap cover. S. Towing cable. T. Left fuel tank filler cap cover. U. Auxiliary generator fuel tank filler cap cover. V. Loader's escape hatch. W. Turret. X. Driver's hatch door. Y. Periscope holder. Z. 105-mm gun. AA. Gun traveling lock. AB. .30 cal. gun. (Picture from TM 9-731AA Medium Tank M4 (105-mm Howitzer) and Medium Tank M4A1 (76-mm Gun).)
The gunner of howitzer tanks was initially provided only with manual traverse. (Picture from TM 9-731AA Medium Tank M4 (105-mm Howitzer) and Medium Tank M4A1 (76-mm Gun).)
The breech of the 105mm howitzer and coaxial machine gun are shown here. The elevation handwheel featured twenty-five labeled notches, each of which represented 1 mil of elevation or depression. The breechblock operating handle can be seen atop the breech; the latch on the front of the handle was squeezed to release the handle, then the lever was pulled to the rear and the right to open the breech, which lacked any semiautomatic function. Upon loading, the howitzer shell would slightly move the handle as the lip of its case struck the extractor. This was the signal to close the breech, pushing the operating handle forward until it latched. (Picture from TM 9-731AA Medium Tank M4 (105-mm Howitzer) and Medium Tank M4A1 (76-mm Gun).)
This tank would have similar modifications as the M4A1(76)W above. (Picture from SNL G-104, Vol. 15.)
The various lids and compartments in the hull subfloor of a 76mm gun tank can can be seen here. (Picture from SNL G-104, Vol. 15.)
"Battling Bitch II" is one of the 1531 M4A2(76)Ws fitted with horizontal volute spring suspension, and the wide tracks and fenders are immediately obvious compared to the vertical volute spring-suspended tanks. Spare track shoes are stowed on the fenders. This vehicle is armed with the 76mm gun M1A1C or M1A2, both of which were fitted with muzzle brakes, and on the turret roof, the spotlight is mounted and pointed downwards. Compared with the early M4A1 Sherman above, later Sherman tanks are almost unrecognizable. (Photo by Richard S. Eshleman.)
While the front offers few points at differentiating the type of tank, this rear view allows identification. The width of the engine grille doors and location of the fuel, water, and oil filler caps indicate the diesel engine. Note the armored cover behind the engine grille doors over the engine oil gauge referred to above. The exhaust pipe for the auxiliary generator engine can be seen exiting the hole inboard of the left-hand mudguard. Gun cleaning rods are stowed on the blanket roll rack on the hull rear plate, and a sledgehammer and the idler wheel adjusting wrench are stowed on the rear deck aft of the engine grille doors. On the right side of the rear hull plate is mounted an infantry phone box. (Photo by Richard S. Eshleman.)
The various lids and compartments in the hull subfloor of a 105mm howitzer tank can can be seen here. (Picture from SNL G-104, Vol. 15.)
The shape of the heavy new turret mounted on the M4A3E2 can be seen here, and the weld lines for the extra armor applied to the gun shield and hull front can be glimpsed. The commander was provided with a cupola. Extended end connectors have been installed to help lessen the tank's ground pressure. (Picture from Development of Armored Vehicles, volume 1: Tanks.)
Fixtures such as the headlights and siren have been omitted from the hull front, however the bow machine gun was retained. This tank lacks the extended end connectors on its T48 tracks. The gun mount welded in place to the hull is of course not the original, and likewise this machine has been rearmed with the 76mm gun.
The extra armor added to the tank's upper front hull is apparent when one looks at the joining welds.
Similarly, armor was added to the hull side as well.
The final drive and differential cover is noticeably sturdier than on non-assault tanks.
The rear hull armor, however, was unaugmented.
The rear deck also remained the same thickness, with its characteristic full-width air intake grilles.
The turret design was based on that of the 76mm gun turret. The ventilator housing is lower relative to the lower edge of the turret rear on the M4A3E2, however, since the extra armor also elongated the turret.
The underside of this turret, cast by the Ordnance Steel Foundry Company, features extensive machining to allow it to clear the hull fixtures. Turrets cast by Union Steel Castings lack this machining and are smoother as they reach down to the hull.
The gun mount T110 was a 76mm gun mount M62 with thick armor welded to its front, and the weld bead for the additional protection can easily be seen in this image. Note that the lower corners of the gun shield had to be angled back to avoid fouling on hull fixtures.
The driver's hatch and periscope with guard can be seen here.
This tank features suspension bogies fitted with the raised arm for the return roller, which helped reduce wear on the track skid from steel track.
This view is of the right side of the turret. The commander's seat is visible, and the gunner's seat, if present, would be in front of and below the TC's seat. The gunner's red turret traverse handle is near the front of the picture, and the white turret traverse hand lever can just been seen near the top of the picture. The black device near the turret ring is the gunner's azimuth indicator. Stowage in the right sponson included three water cans in the compartment in the center of the picture. The hexagonal hole through which the turret ring is visible would normally be covered by the traverse lock.
This is a more detailed view of the gunner's station. The azimuth indicator is on the far right, the red turret traverse handle is visible again, and the white traverse hand lever can be seen in front of the azimuth indicator. The elevating handwheel has a red handgrip, and the 75mm gun can be seen in the upper left. The turret control box is positioned above the gunner's controls to the front.
M4A3E2s featured wet ammunition stowage, and an open ammunition rack is illustrated here. The driver's seat is in front of this ammo rack.
The driver's position is the subject of this photo. The driver and assistant driver were separated by the transmission assembly. The two steering levers can be just seen in front of the driver's seat, and his instrument panel is to the left. The rusted gearshift lever is just to the right of the driver's seat, and the black knob to the right of the steering levers is the hand throttle. The four brackets above the transmission itself were for stowing extra periscopes; spare periscope heads could be stored in the box below the periscopes themselves. Between the drivers on the hull roof is a ventilator fan. The ball mount for the bow machine gun can be seen in the front hull plate on the right of the picture.
From the front, this M4A3(76)W HVSS is visually virtually identical to the M4A2(76)W HVSS above. In the center of the 47° glacis is the gun travel lock, and the sharp-nosed single-piece final drive and differential cover is mounted. The tracks on this vehicle are the double-pin T84.
This view shows the later exhaust deflector fitted to the GAA-engined Shermans. It consisted of two armored pieces that could be raised independently. Directly under the blanket rack are supports for the deflectors when they are raised. This tank also has some sections of track mounted incorrectly.
The commander's vision cupola is detailed here. He was provided with a rotating periscope in the cupola door, and six vision blocks ringed the base of the cupola. The revised vane sight is mounted in front of the cupola, and outboard of this is the cover for the gunner's periscope. A stowage clip for the barrel of the roof-mounted machine gun is folded onto the turret roof, and a searchlight mount can be seen towards the bottom right of the image.
The loader's oval hatch is slightly ajar on this machine. The springs to assist the loader in the hatch's operation are obvious, and a hold-open catch can be seen to the rear in front of the antenna mount. The loader's periscope and guard can be seen in the foreground, and the mounting post for the .50cal MG is in the turret rear between the loader's hatch and commander's cupola.
The pistol port is open on this tank, and the mechanism for opening and closing it can be seen.
The armored casting for the turret ventilator was substantial, as can be seen here. The welding for the machine gun stowage receptacle is also visible.
This somewhat derelict M4A3(105) HVSS Sherman features the armored cover protecting the gunner's telescope. This could be pivoted down out of the way when in action, and a path for its movement has been machined out of the howitzer shield. (Photo by Richard S. Eshleman.)
The underside of the left air intake grille can be seen from the rear, and with the missing tracks the dual nature of the road and idler wheels is visible. (Photo by Richard S. Eshleman.)
The gunner's telescope cover is rotated down on this machine.