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M48
M48A1
M48A2
M48A3
M48A5

90mm Gun Tank M48 Patton 48^{1-12,22,24,27,29}

Virtually intended as a lighter version of the 120mm gun tank M103, the M48 used similar large elliptical castings for its turret and hull. M48 had a small, oval driver's hatch and the .50cal M2HB machine gun mounted at the Chrysler-designed commander's cupola was exposed. The drivers of M48s controlled the tanks through an aircraft-style steering wheel, instead of the single wobble stick control found on the M46 and M47. Early M48s had a round muzzle brake or cylindrical blast deflector, while later vehicles were equipped with a Y-shaped or T-shaped muzzle brake. The fire control system was complex for the time, using an optical rangefinder connected to a mechanical ballistic computer to calculate and transmit superelevation to the gun mount and sights. Initial difficulties with the computer led to interim fire control systems being installed so that the tanks could be fielded as soon as possible. The phase I fire control system used on the pilot vehicles simply used the gunner's periscope and installed the commander's telescope T161 in the right-side rangefinder blister. Estimated range was inputted via the range drive T25, and the ballistic drive T24 connected the sights and range drive. The commander's rangefinder T46E1 and gunner's telescope T156E1 were introduced in the phase II fire control system. The telescope replaced the right-hand .30 caliber coaxial machine gun that was present on the pilot tanks. The ballistic drive T24E1 was used; compared to the T24, the T24E1 was fitted with a shorter output arm, and was still not connected to the rangefinder. The phase III system was similar to the phase II system, and the phase IV system finally introduced the ballistic computer instead of the range drive. The ballistic drive T24E2 found in the final arrangement was a sturdier design that connected the rangefinder into the system as well.

Late-production tanks also were fitted with an infrared periscope for the driver, and his hatch was enlarged during production. The early small driver's hatch incorporated a mechanism that dropped his three periscope heads to provide clearance for the hatch door as it swung to the right, and the driver then had to reposition the periscopes by hand once the hatch was closed again. The later large hatch door simply raised up above the periscope heads before it swung open. Though both types of hatches had locks to hole the hatch open, only the large hatch was fitted with a lock to hold the hatch closed. Tanks with the small driver's hatch were fitted with the Chrysler cupola, and this cupola also lasted for production of 1,805 large-driver hatch tanks. The Chrysler cupolas on these latter were replaced by the cupola M1 and were redesignated as M48A1. One hundred twenty M48 hulls were found to be ballistically deficient, and were therefore used for training only. These vehicles were designated M48C. Short range was a problem for the M48, and four jettisonable 55gal (210L) fuel drums could be mounted on the rear deck to increase the tank's range to about 135 miles (217km).

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90mm Gun Tank M48A1 Patton 48^{1,7-13,17-18,26,28,29}

M48A1 incorporated the larger driver's hatch and a new M1 cupola for the commander designed by Aircraft Armaments, Inc. The cupola engulfed the rear of the .50cal machine gun, and the weapon could therefore be loaded from inside the tank. The M1 cupola had a periscope in the roof for all-round visibility, and five vision blocks ringed the base. An equilibrator spring helped counterbalance the machine gun cradle's inherent noseheaviness. However, interior room was lacking in the cupola, and due to this the size of the machine gun ammunition box was severely limited.

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90mm Gun Tank M48A2 Patton 48^{1,8-15,18-19,23,25,29-30}

M48A2 was powered by a more efficient fuel-injected version of Continental's V-12, and when coupled with the extra room for fuel tanks provided by the more compact design of this engine, the range of the M48A2 was greatly increased. The rear of the M48A2 hull was redesigned from a solid plate to one incorporating exhaust louvres, and the hull intake grilles on the each side of the rear deck surrounded a solid center area that was overtop of the exhaust tunnel. The infrared signature of the tank was reduced with this new arrangement. Compare this to M48 and M48A1, where the exhaust was discharged just behind the turret. The engine's air cleaners were also placed in the fighting compartment side of the engine bulkhead for easier maintenance. Suspension components of M48A2 also received an upgrade, since failures were noted in earlier tanks. The compensating idler wheel attachment was modified, a double bump spring replaced the single unit on the first road wheel arm, friction snubbers replaced the hydraulic shock absorbers on the tank. The second and fourth track return rollers were deleted. The driver received a larger steering wheel, and the transmission shifter was moved from behind the steering wheel to the floor on the driver's right. The M48A2 had only one personnel heater exhaust pipe exiting to the left of the roof of the driver's compartment, compared to the exhausts for two heaters on earlier tanks. M48A2 replaced the electric-hydraulic Oilgear turret control system with a constant pressure hydraulic system from Cadillac Gage that was more precise, compact, reliable, and cooler-running. The tank's fenders were also changed from a round to a flat profile. Beginning with tank serial number 1806, the commander's cupola was fitted with terminal board assemblies that allowed electrical supply to the cupola.

The 90mm gun tank M48A2C replaced the stereoscopic rangefinder with a more user-friendly M17 coincidence model, and initially the periscope M20A3F was fitted for the gunner, but the daylight/infrared periscope M32 could later be substituted. The articulated telescope M105 was installed as the gunner's secondary sighting device. M48A2C also used a new ballistic drive which accounted for temperature fluctuations, a larger bore evacuator was fitted to the 90mm gun, and the metric system replaced English measurements as the basis of the tank's fire control system. When the ballistic computer M13A1 had its range scale changed from yards to meters, it was redesignated M13A1C. The auxiliary track tensioning wheels were deleted from M48A2C. One thousand three hundred forty-four M48A2s were modified to M48A2C standard.

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90mm Gun Tank M48A3 Patton 48^{1,7-12,15-18,26}

The M48A3 modification fitted M48A1s with a diesel engine for greater fuel economy and reduced danger from fuel explosions. The rear deck was reworked to incorporate M60 grilles and exhaust louvres, and rear fender-mounted dry air cleaners were used instead of the oil bath models of the earlier gasoline engines. The auxiliary generator and engine were deleted, since the tank's diesel engine was more efficient than even the smaller auxiliary generator engine. The tank received the suspension upgrades of the M48A2. The personnel heater was changed again, to the type used in the M60, with its characteristic exhaust routed to the right (instead of left) side of the tank. The M48A3's fire extinguisher was improved as well. M48A3 was able to mount a xenon white light or infrared searchlight on the gun shield above the 90mm gun. The gun shield cover was waterproofed, and the crew was provided with a spall liner inside the tank and an air filtration system to protect them from chemical or biological attack. The turret control system was changed from the original Oilgear type to a new design by Cadillac Gage, and the fire control system of the M48A3 was also upgraded. The ammunition box for the .50cal MG was reduced from 100 to 50 rounds due to lack of space in the commander's cupola, but conditions were still cramped for the commander. Late tanks starting with serial number 601W used an hydraulic brake system, improved steering and transmission shifting controls, an adapter vision ring under the cupola, an improved turret inflatable seal, improved sighting and fire control instruments that included infrared capability, and metal screening on the turret cargo racks.

Bowen-McLaughlin-York, Inc., converted 578 tanks to M48A3 (Mod. B) standard starting in 1967. The Mod. B tanks differed from the earlier M48A3s by having armor framing running along the tops of the engine exhaust louvres, armor boxes surrounding the taillights, and an adapter ring incorporating vision blocks which raised the commander's cupola by about 5" (13cm). This, combined with a redesign of the cupola door, provided more room for the tank commander. M48A3 (Mod. B) tanks also received driver's controls and gauges from the M60A1 tank, the fuel lines were relocated, and the suspension was modified by the addition of knock-out holes for the torsion bars and the redesign of the track return roller mud shields. Detachable headlights were mounted, and the fender telephone intercom was mounted in a higher position. Infrared fire control equipment was installed in the upgraded tanks as well. The upgrades that BMY installed were eventually retrofitted to all M48A3s, and the Mod. B designation was subsequently deleted.

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105mm Gun Tank M48A5 Patton 48, late production^1,9-12,18-21

The increasing obsolescence of the 90mm gun forced another upgrade project onto the M48A3 and M48A1. M48A5 used the 105mm gun M68 of the M60 tank, and as many M60A1 components as possible were incorporated. As detailed in the table above, the very large M1 cupola was replaced on M48A5s in August 1976 by a model designed by Israel's Urdan Associated Steel Foundries Company, Ltd. (now Urdan Industries, Ltd.), which was much shorter and used three periscopes mounted around a hatch that could be opened vertically a short distance to grant the tank commander protected visibility. M60D machine guns were also provided for the tank commander (replacing his .50cal machine gun) and loader, and main gun ammunition stowage was increased by 11 rounds to 54. M48A5s with the new features were for a time called M48A5PI (i.e., M48A5 Product Improved), but this designation was later returned to simply M48A5 as older vehicles were upgraded with the new features. Tanks with serial numbers A3001-A3374 retained the cupola M1, while serial numbers A1001-A1999 and A3375-A3999 featured the low-profile cupola.

In December 1965, with series production of the 152mm gun-launcher M60A2 expected, it was planned to mount a portion of the newly-created surplus of M60 turrets onto 243 spare M48A1 hulls converted to M48A3 standard. Initially known as the XM735, these vehicles were later designated M48A4. However with the limited numbers of M60A2s actually produced, the M48A4 project was cancelled after only two pilots had been converted.

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References

1. Hunnicutt, R.P. Patton: A History of the American Main Battle Tank, volume 1. Navato, CA: Presidio Press, 1984.
2. TM 9-7012 90-mm Gun Tank M48. Washington, DC: Department of the Army, 30 August 1954.
3. TM 9-6013 Range Drive T25. Washington, DC: Department of the Army, 14 August 1953.
4. TM 9-6159 Field and Depot Maintenance Ballistic Computer T31. Washington, DC: Department of the Army, 5 April 1956.
5. TM 9-6023 Ordnance Maintenance Range Finder T46E1. Washington, DC: Department of the Army, 5 May 1955.
6. TM 9-6163 Ordnance Maintenance Ballistic Drive T24E2. Washington, DC: Department of the Army, 12 April 1955.
7. FM 17-79 Tank, 90-mm Gun, M48. Washington, DC: Department of the Army, 13 October 1955.
8. ORD 9 SNL G-254 Tank, 90-mm Gun, M48 (T48), M48A1, and M48C. Washington, DC: Department of the Army, 27 May 1955.
9. Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
10. Miller, David. The Illustrated Directory of Tanks of the World. Osceola, WI: MBI Publishing Co., 2000.
11. Decker, Oscar C. "The Patton Tanks: The Cold War Learning Series." Camp Colt to Desert Storm: The History of U.S. Armored Forces. Eds. George F. Hofmann, Donn A. Starry. Lexington, KY: University Press of Kentucky, 1999.
12. Foss, Chris. Modern Tanks. Glasgow: HarperCollins Publishers, 1995.
13. TM 9-1005-219-35 Field Depot and Maintenance Manual Commander's Machinegun Cupola M1. Washington, DC: Department of the Army, 17 November 1961.
14. TM 9-7022 Operation and Organizational Maintenance: 90-mm Gun Full Tracked Combat Tank M48A2. Washington, DC: Department of the Army, 18 March 1958.
15. TM 9-1220-203-34 Field Maintenance Manual Ballistic Computers M13, M13A1, M13A1C, and M13A1D. Washington, DC: Headquarters, Department of the Army, 4 March 1960.
16. TM 9-2350-224-10 C9 Operator's Manual Tank, Combat, Full Tracked: 90-mm Gun, M48A3 W/E (2350-895-9154). Washington, DC: Headquarters, Department of the Army, 28 June 1966.
17. TM 9-2350-224-20 Organizational Maintenance Manual for Tank, Combat, Full Tracked: 90-mm Gun, M48A3 W/E (2350-895-9154). Washington, DC: Headquarters, Department of the Army, 5 June 1963.
18. Myszka, John. Israeli Military Vehicles: The First 50 Years. Australia: Mouse House Enterprises, 1998.
19. Federation of American Scientists. "M48 Patton." DOD 101. 7 August 1999. 4 March 2001 <http://www.fas.org/man/dod-101/sys/land/m48.htm>. DOD 101
20. Cullen, Tony, and Christopher F. Foss, eds. Jane's AFV Retrofit Systems 1994-95. Seventh ed. Coulsdon, Surrey: Jane's Information Group, Ltd., 1994.
21. TM 9-2350-258-10 C5 Operator's Manual Tank, Combat, Full Tracked: 105-mm Gun, M48A5 NSN 2350-00-582-5595 NSN 2350-01-059-1504. Washington, DC: Headquarters, Department of the Army, 27 April 1984.
22. TM 9-7013-1 Ordnance Maintenance: Turret Assembly and Turret Race Assembly, Commander's Cupola Assembly, Turret Ventilating Blower, Universal Joint Assembly, Final Drive, and Steering and Shifting Control Assembly, for the 90-mm Gun Tank T48. Washington, DC: Department of the Army, 10 March 1954.
23. TM 9-6191 Ordnance Field and Depot Maintenance Ballistic Drive M5A1 (T24E5). Washington, DC: Department of the Army, 26 August 1957.
24. TM 9-6065 Ordnance Maintenance Ballistic Drives M3 (T23E1), M4 (T23), T23E2 and T24. Washington, D.C.: Department of the Army, 24 November 1954.
25. TM 9-2805-206-35 Field and Depot Maintenance Manual Engine, Gasoline: "V" Type, Air Cooled, 12-cylinder, Fuel Injected, Supercharged--2805-695-6237 (Continental Model AVSI-1790-6) and Fuel Injected, (Unsupercharged)--2805-293-9662 (Continental Model AVI-1790-8). Washington, DC: Headquarters, Department of the Army, 4 November 1959.
26. Conversion Guide Covering Modification of Tank, Combat, Full Tracked: 90-mm Gun, M48A1 to Tank, Combat, Full Tracked: 90-mm Gun, M48A3 (Mod. B) Volume 1 of 2 Hull. Defense Engineering, Defense Operations Division, Chrysler Corporation, December 1966.
27. TM 9-7012 90-mm Gun Full Tracked Combat Tanks M48, M48A1, and M48C. Washington, DC: Department of the Army, 30 August 1954.
28. Frye, W.B. Report No. DPS/IT/5098/1 Automotive Division Report on Vulnerability Evaluation of the M48 Tank and Cupolas M1 and M13, Against Small Arms Attack (U): First Report on OTAC Project IT-5098 (AD-1276). Aberdeen Proving Ground: Development and Proof Services, August 1959.
29. TM 9-500 C3 Data Sheets for Ordnance Type Materiel. Washington, DC: Headquarters, Department of the Army, 12 October 1966.
30. FM 17-12 Tank Gunnery. Washington, DC: Headquarters, Department of the Army, 30 November 1964.

Last updated 7 Oct 2024.
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