The riveted construction of the medium tank M3 is obvious here. This vehicle is not fitted with stabilization since it lacks counterweights on the 37mm or short 75mm M2 guns. The machine gun in the commander's cupola is present in its right aperture, and one of the driver's hull machine guns has been retained. Track grousers are stored in the box below the driver's hatch, and the tank's siren is positioned below the 75mm gun. Here the crew, Cpl. Larry Corletti, Pvt. Murril Chapman, and Pvt. Louis Robles, practice dismounting from a disabled vehicle. (Picture taken 12 Feb 1943 by Sgt. Calvano; available from the U.S. Army Center of Military History.)
The asymmetric design of the tank is highlighted in this top view. A towing cable and tools are stowed on the rear deck, and the filler covers for the four fuel tanks can be seen on each side of the engine air intake grille. (Picture from TM 9-750 Medium Tanks M3, M3A1, and M3A2.)
This early-production tank is fitted with pepperpot-style exhaust mufflers in contrast to the vehicles below. (Picture from TM 9-750 Medium Tanks M3, M3A1, and M3A2.)
This tank has the later air cleaner and exhaust system. The rectangular exhaust pipes are now in the center, with the engine's air cleaners in each upper corner. Engine access was provided by the double doors, and the hole in the rear armor was for the engine hand crank. Taillight groups can be seen above the fenders. A pistol port is visible on the superstructure's right side, and an antenna mount is mounted on the opposite side of the superstructure.
The air cleaners were vulnerable to damage from enemy fire, so extra protection was added around them.
A close-up of the twin exhaust tips is shown here.
A cross-sectional view of the tank is provided in this image. This tank also has the early exhaust and air cleaner setup. (Picture from TM 9-750 Medium Tanks M3, M3A1, and M3A2.)
1. Driver's seat. 2. Radio operator's seat. 3. 75-mm gunner's seat. 4. 37-mm gunner's seat. 5. 37-mm loader's seat. 6. Tank commander's seat. 8. Cal. .30 machine gun. 9. Cal. .30 machine gun. 10. 37-mm gun. 11. 75-mm gun. 12. 2 cal. .30 machine guns. 13. Protectoscopes. 14. 51 rounds 37-mm ammunition carried in turret. 15. 13 rounds 37-mm ammunition. 16. 11 rounds 37-mm ammunition. 17. 42 rounds 37-mm ammunition. 18. Ten 100-round belts cal. .30 ammunition. 19. 20 rounds 37-mm ammunition. 20. Fourteen 250-round belts containing 225 rounds cal. .30 ammunition. 21. Two 250-round belts containing 225 rounds cal. .30 ammunition. 22. Twenty-five 100-round belts cal. .30 ammunition. 23. 41 rounds 75-mm ammunition; six 100-round belts cal. .30 ammunition. 24. 42 rounds 37-mm ammunition. 25. Submachine gun. 26. Submachine gun. Carried in tank but not shown on drawing are 9 rounds 75 mm ammunition carried in cartons and twenty-four 50-round clips cal. .45 ammunition. (Picture from TM 9-750 Medium Tanks M3, M3A1, and M3A2.)
Details of the mounting of the twin hull machine guns are shown in this image. (Picture from TM 9-750 Medium Tanks M3, M3A1, and M3A2.)
The US version of the M3 kept the radio in the hull and featured a large machine gun cupola for the tank commander. The turret consequently had a short overhang, and the TC's cupola is very prominent. In this image, we are looking at the rear of the turret, and the cupola is rotated to almost 9 o'clock. A vision slot is open on the side of the cupola, and a ventilator is visible beside the cupola.
The front of the TC's cupola is shown here. The aperture for the .30cal machine gun is on the commander's right side, and a protectoscope was housed in the opposite opening. Below, the opening for the 37mm gunner's periscope M2 can be seen on the turret front.
This is a later-production vehicle, as indicated by the ventilators and the lack of side hull doors. The pistol ports and roof hatch over the 75mm gun sponson were retained, however. A stowage box is mounted on the rear deck.
The suspension on the M3 was based on that of the medium tank M2. This vehicle is not fitted with the later, heavy-duty volute springs that necessitated moving the track return roller to the rear of the assembly.
The different turret on this vehicle marks it as a British Grant I. The British did not use the turret machine gun cupola and placed a radio in the bustle of the turret of the Grant. The British turret was lower and wider as a consequence. This vehicle retains the hull side doors, but the hull machine gun ports have been plugged.
The profile view of the British turret shows the lengthened radio bustle at the rear.
Looking through the open starboard side door, the breech of the 75mm gun and the 75mm gunner's seat is visible. The driver's black padded seat is beyond the 75mm gunner's seat, and the 37mm turret shield is to the 75mm gunner's left rear.
A second view of the 75mm gun, including the gunner's periscope M1, is shown here. The piston for the gyrostabilizer is mounted to the right of the 75mm gun, but the rest of the equipment is missing.
The short 75mm gun M2 is shown here with the parts of the gun mount labeled. (Picture from FM 23-95 75-mm Tank Gun M2 (Mounted in Medium Tank M3).)
The various components of the 75 mm gun stabilizer are outlined here. (Picture from TM 9-750 Medium Tanks M3, M3A1, and M3A2.)
The interior of the tank behind the 75mm gunner is shown here. The engine propeller shaft runs beneath the turret, and an oil cooler and oil tank are attached to the bulkhead. The two gauges facing us above the propeller shaft are fuel gauges, and the red handles are for discharging the carbon dioxide cylinder fire extinguishers. The red fire extinguisher cylinders themselves can be seen under the turret basket.
Looking beyond the 75mm gun, we can see the driver's controls and instrument panel. The steering levers are in front of his seat, and the white gear shift lever is to his right. The handwheel on the right of the image is for traversing the 75mm gun, and this handwheel also contained the solenoid firing button. The riveted construction of the vehicle is evident on the inside as well, and the rivets had the unfortunate tendency to break apart when hit and ricochet around the cramped interior of the vehicle.
The hydraulic turret traversing mechanism is detailed in this picture. The electric motor on the turret floor was directly connected to the hydraulic pump, which drew hydraulic oil from the reservoir on the turret basket wall. The pump delivered the oil under pressure to the inlet port of the manually-operated control valve, which governed the flow of oil through one of two tubes that were connected with the hydraulic motor. Depending on which tube through which the oil flowed, the hydraulic motor turned in one or the other direction. The hydraulic motor's shaft was splined through two pairs of spur gears to a pinion that engaged with the stationary ring gear on the tank hull. The valve control handle could be turned to the right or left to determine the tube through which the oil would flow, and therefore determine the direction of turret rotation. A manual traverse drive was also mounted along with a shifting lever that allowed the traverse to be changed from hydraulic to manual. (Picture from TM 9-1750H Ordnance Maintenance--Hydraulic Traversing Mechanism (Logansport) for Medium Tank M3 and Modifications.)
The manual traversing gear mechanism and hydraulic control valve handle are detailed installed in the turret. (Picture from TM 9-1750H Ordnance Maintenance--Hydraulic Traversing Mechanism (Logansport) for Medium Tank M3 and Modifications.)
The hydraulic control valve is shown here. It was a manually-operated two-way piston valve that directed the flow of oil to one side or the other of the hydraulic motor, thereby rotating the turret in the desired direction. Electric switches for firing the turret guns were also mounted on the valve handle. It was necessary to squeeze the trigger, which flipped the safety switch, before the two firing switches were energized. The handle and trigger would return to their neutral positions if they were released, stopping turret traverse and de-energizing the firing switches. (Picture from TM 9-1750H Ordnance Maintenance--Hydraulic Traversing Mechanism (Logansport) for Medium Tank M3 and Modifications.)
The manual traversing gear mechanism was geared to a pinion that meshed with the stationary ring gear on the tank hull. Two pairs of bevel gears and one pair of spur gears were used in the manual traversing mechanism. The shift lever was used to engage either the manual mechanism or hydraulic systems. (Picture from TM 9-1750H Ordnance Maintenance--Hydraulic Traversing Mechanism (Logansport) for Medium Tank M3 and Modifications.)
This image is looking into the 37mm turret from the port hull side door. The tank commander's seat is at the top right corner of the picture, the 37mm loader's seat is directly across the turret, the rear of the 37mm gunner's seat can be glimpsed to the left of the frame, and 37mm ammunition racks line the turret walls.
The turret crew's positions relative to each other can be better seen here. The gunner's elevation handwheel has a black handle and is positioned parallel to the 37mm gun, and the black gyrostabilizer control unit can be seen across the turret near the turret ring.
The parts of the stabilizer for the 37 mm gun are detailed here. (Picture from TM 9-750 Medium Tanks M3, M3A1, and M3A2.)
The opposite side of the turret is shown here. The cables hanging down in this image can be seen in the foreground of the picture above. (Picture from FM 23-81 37-mm Gun, Tank, M6 (Mounted in Tanks).)
Details of the commander's hatch are shown here. A rotatable periscope mount is allowing light through.
The tank's auxiliary generator, the Homelite heater-generator HRH-28, was mounted in the left rear corner of the fighting compartment. It supplied 1500 watts, 30 volts DC for charging the tank's batteries; and a heater element preheated the main engine as well as provided heat for the crew. The Homelite HR-28 electrical generator was driven by a small 3400-3600 rpm, 2-cycle, single-cylinder Homelite HR gasoline engine. (Picture from TM 9-1752 Ordnance Maintenance--Auxiliary Generator (Homelite Model HRH-28) for Medium Tanks M3.)
This cast, smooth-lined M3A1 is armed with the short-barreled 75mm gun M2, and since neither it nor the 37mm guns are fitted with counterweights, this tank also lacks stabilization. This tank also has the early suspension bogies which have the return roller on top of the brace. The aperture to the left of the 37mm gun was for the gunner's periscope. The machine gun in the cupola emerged from the right opening; the left was for a vision slot. There are antenna mounts behind the turret and behind the front hull pistol port. (Picture from Tank Data, vol. 2.)
The M3A2 was the first of the series to feature a welded hull. The sharp lines and lack of riveting are obvious when compared with the tanks above. (Picture from Tank Data, vol. 2.)
Most of the identifying features for M3A5 are on the rear of the vehicle, since the major difference between M3A5 and M3 is that the former is powered by twin diesel engines rather than the radial gasoline engine. This tank is not fitted with stabilization since it lacks counterweights under the 37mm gun and around the end of the short 75mm gun M2's barrel. It also is running on the T49 parallel bar steel tracks. (Picture from Development of Armored Vehicles, volume 1: Tanks.)
This later-production tank has its side door welded up, and the pistol port has also been eliminated on this side. The engine air inlet grille is open, and can be seen behind the stowage box.
The tank is fitted with gun stabilizers. The cylindrical counterweight is mounted under the 37mm gun, and the short barrel of the 75mm gun M2 has a counterweight fitted around it. Note the pistol port in the right hull side remained even after the doors had been eliminated.
Looking forward into the open engine compartment, the fuel filters can be seen outboard of the oil filters. The valve rocker covers for the two engines are low in the engine compartment, and between them are the water outlet and exhaust manifolds. Two cylindrical air cleaners are just visible at the lower corners of the opening.
This is a 3/4 front view of the GM 6046 engine. The power from each engine was sent through its drive shaft and gear to a common driven gear which in turn drove the propellor shaft. The individual engines were designated model 671LA24M (right-side engine) and 671LC24M (left-side engine). The engine weight as installed was 4855lb (2202kg). (Picture from TM 9-1750G Ordnance Maintenance--General Motors Twin Diesel 6-71 Power Plant for Medium Tanks M3A3, M3A5, and M4A2.)
The legend for this cross-sectional view is as follows: 1. Oil cooler adapter. 2. Oil cooler. 3. Blower housing. 4. Blower rotors. 5. Air cleaner. 6. Secondary fuel filter. 7. Camshaft. 8. Rocker arm. 9. Injector. 10. Injector control rack tube lever. 11. Water outlet manifold. 12. Exhaust manifold. 13. Balancer shaft. 14. Valve rocker cover. 15. Push rod. 16. Section of piston and connecting rod. 17. Air box. 18. Solenoid air inlet control. 19. Air inlet housing. 20. Connecting rod bearing shell. 21. Crankshaft. 22. Main bearing shell. 23. Lubricating oil pump assembly. 24. Lubricating oil pump driven gear. 25. Air heater. 26. Air heater fuel pipe. 27. Clutch shift levers. (Picture from TM 9-1750G Ordnance Maintenance--General Motors Twin Diesel 6-71 Power Plant for Medium Tanks M3A3, M3A5, and M4A2.)
The different internal arrangement necessitated by the twin diesel engines can be gleaned when this image is compared with the cross-section of the M3 above. (Picture from Tank Data, vol. 2.)
Compared to the sharp-edged hull machines above, the relative lack of rivets due to welding much of this vehicle is obvious. (Picture from Tank Data, vol. 2.)
The dearth of rivets caused by the use of welding is well illustrated by looking at the side of the tank. This vehicle is a later-production example, as the side door has been welded closed.
A closer view of the welded shut side door and pistol port are provided in this picture.
Welding the hull did not eliminate all rivets, but their use was drastically reduced.
Although the side doors have been welded shut, the tank retains apertures for both hull machine guns.
Details of the counterweight on the 75mm gun M2 are provided here.
The counterweight for the 37mm gun, however, is not present on this tank, although its aperture remains unplugged.
The rear deck featured twin armored air intake louvres protected by mesh screens. Filler cap covers can be seen on the rear deck and in front of the sponson stowage boxes for fuel, water, and lubricating oil.
The rear armor was extended downward compared to radial-engine tanks, and the rear engine access doors were necessarily deleted.
The mufflers for the engines met in the center of the rear of the vehicle, and a deflector was mounted to keep the exhaust gases from stirring up too much dust. The solid lower rear hull can be contrasted with the radial-engined tank above.
The reason for the changes to the rear armor was that the radiators for the GM 6046 were mounted at the rear above the mufflers, a concern that tanks powered by the air-cooled radials did not have.
This picture is looking forward from the rear of the tank. The long rectangular engine inspection plates can be seen in the foreground, each with a round cover for engine oil drain plug access. Since this tank has no side hull doors, it was equipped with a floor escape hatch, the opening for which which can be seen in front of the right-hand engine inspection plate.
Looking straight up into the escape hatch opening, the front of the tank is to the right of the image. The transfer case can be seen to the left, and the propeller shaft runs off to the right to engage the transmission. Control linkages are near the bottom of the image, and a 75mm ammunition rack can be seen to the right. The underneath of the turret basket is directly overhead.
The large Chrysler multibank engine installed in M3A4 necessitated a longer hull to fit in the tank. The distance between the bogies was also therefore increased, and the rear deck roof and engine compartment floor had bulges to accommodate the A57 engine. (Picture from Development of Armored Vehicles, volume 1: Tanks.)
A. Tube, water pump air relief (engine no. 1 to no. 2). B. Coil, ignition, assembly (no. 1 engine). C. Cleaner, air, crankcase ventilator, assembly. D. Shaft, drive, tachometer. E. Pump, water, assembly (no. 1 to no. 5 engine). F. Tube, water pump air relief (no. 1 engine). G. Filter, oil (absorption type). H. Coil, ignition (no. 5 engine). I. Pipe, exhaust (nos. 4 and 5 engines). J. Tube, fuel pump to branch connection, assembly (for nos. 4 and 5 carburetors). K. Connection, water pump air relief tube. L. Pump, water, assembly (no. 5 engine). M. Distributor, ignition, assembly (no. 5 engine). N. Tube, water pump air relief (no. 4 to no. 5 engine). O. Tube, fuel pump to no. 1 carburetor, assembly. P. Plate, serial number, engine. Q. Pump, fuel, assembly. R. Coil, ignition, assembly (no. 4 engine). S. Support, engine, rear. T. Pump, water, assembly (no. 4 engine). U. Tube, radiator outlet, assembly (nos. 4 and 5 engines). V. Distributor, ignition, assembly (no. 4 engine). W. Pan, oil. X. Plug, drain, oil pan. Y. Tube, fuel pump to branch connection, assembly (for nos. 2 and 3 carburetors). Z. Distributor, ignition, assembly (no. 3 engine). AA. Pump, water, assembly (no. 3 engine). BB. Tube, radiator outlet, assembly (nos. 2 and 3 engines). CC. Coil, ignition, assembly (no. 3 engine). DD. Cock, drain, cylinder water jacket, assembly. EE. Distributor, ignition, assembly (no. 2 engine). FF. Tube, water pump air relief (no. 2 to no. 3 engine). GG. Pump, water, assembly (no. 2 engine). HH. Coil, ignition, assembly (no. 2 engine). II. Distributor, ignition, assembly (no. 1 engine). JJ. Generator, assembly. KK. Pipe, exhaust (nos. 1, 2, and 3 engines). (Picture from TM 9-1750F Ordnance Maintenance--Power Unit for Medium Tanks M3A4 and M4A4.)