90mm Gun Tank M47 Patton 47^1-20

The M47 was essentially an M46 fitted with the narrow turret from the T42 tank prototype. The front hull had a sharper slope, however, and the rotoclone blower placed between the drivers on the M46 was deleted. The turret had a long bustle which housed the radio and a ventilator. The "eyes" of the gunner's stereoscopic rangefinder protruded from the top sides of the turret. Production issues with the rangefinder led to the first fifty-one tanks being delivered without the unit, and the rangefinder's turret apertures in these machines were blanked off. Early tanks were armed with a 90mm gun featuring a single-baffle muzzle brake, and late tanks had a T-shaped blast deflector. Most M47s, however, were produced with a cylindrical blast deflector. Later tanks also had a taller .50cal MG pintle placed farther forward on the roof compared to earlier vehicles.

The tank was originally nicknamed Patton II, but the name was changed to Patton 47 a few weeks later. On 9 November 1950, the US Army changed the basis of its tank designation system from weight to the caliber of the vehicle's main gun. The M47, which would have been a medium tank previously, therefore became a 90mm gun tank.

The engines differed in the following ways: the AV-1790-7 used cylinders from the AOS-895-3 engine and a new accessory case suitable for the revised cam drive angle. The AV-1790-7B replaced the earlier 150-ampere main generator with a 300-ampere model. Late -7B engines used a 17psi (1.2kg/cm²) low oil pressure warning light switch, replacing the earlier 30psi (2.1kg/cm²) switch. Early -5B engines had a pressure controlled 50psi (3.5kg/cm²) oil-cooler-bypass valve, which was replaced in subsequent production with an oil-cooler-thermostatic-bypass valve that allowed oil to bypass the cooler until temperature was 185°F (85.0°C). A 148°F (64.4°C) valve replaced this late in production. Early -5B engines featured exhaust manifolds made up from pieces with slip joint connections. This design was superseded by one with waterproof welded bellows-type joints.

The transmission models had the following differences: the CD-850-4A replaced the CD-850-4's right output double-acting oil pump check valve with a single-acting type and omitted the converter-oil-line check valve, eliminating the need for a converter-external-oil-bypass line to prevent converter-oil high temperatures. The -4A's transmission valve body was modified in order to increase oil pressures in all ranges. Oil slingers were added to the brake hubs on the -4A, thereby reducing horsepower losses. The CD-850-4A used a new method of retaining the stator assembly and the freewheel-roller-race. Two bushings were added to the steering clutch apply lines in the -4A's rear housing; the -4A's housing also omitted the pad on the top rear that featured speedometer bracket studs, and the area of the housing that covered the steering shaft drive gears was shrunk to increase clearance for the tank hull. CD-850-4 used electrical speedometer and tachometer units, replaced in subsequent transmission models by mechanical gages.

An upgrade program for the M47 was started in the late 1960s and resulted in the M47M. M47M used the engine and fire control system from the 105mm gun tank M60A1. The engine, Continental's AVDS-1790-2A supercharged diesel, had its exhaust vented through rear louvres like on the M60, replacing the M47's fender-mounted mufflers. The transmission used was the CD-850-6A. The assistant driver was eliminated in favor of a 22-round 90mm ammunition rack, and the small track tension idler wheel was deleted as well. To compensate for the location of the new engine's oil pan, the rear road wheel was moved 3.8" (9.7cm) to the rear. The tank's shock absorbers were also dropped in favor of friction snubbers. Five hundred forty-seven M47s were modified to M47M standard by Bowen-McLaughlin-York, Inc., in a factory built in Iran for M47M production. The improved tank was used by Iran and Pakistan.

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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 9-718A 90-mm Gun Tank M47. Washington, DC: Department of the Army, 9 January 1952.
3. Manuscript of TM 9-718A C1. Washington, DC: Office of the Chief of Ordnance, April 1952.
4. TM 9-2350-200-12 Operation and Organizational Maintenance 90-mm Gun Full Tracked Combat Tank M47. Washington, DC: Headquarters, Department of the Army, 7 October 1958.
5. FM 17-78 Tank, 90-mm Gun, M47. Washington, DC: Department of the Army, 15 April 1955.
6. ORD 9 SNL G-262 List of All Service Parts of Tank, 90-mm Gun, M47. Washington, DC: Department of the Army, 23 December 1953.
7. ORD 9 SNL G-262 List of All Service Parts of Tank, Combat, Full-tracked: 90-mm Gun, M47. Washington, DC: Department of the Army, 1 April 1957.
8. TM 9-1730E Hydraulic Turret-traversing and Gun-elevating system for 76-mm. Gun Tank T41E1 and 90-mm. Gun Tank M47. Washington, DC: Department of the Army, 3 October 1952.
9. TM 9-6065 Ordnance Maintenance Ballistic Drives M3 (T23E1), M4 (T23), T23E2 and T24. Washington, D.C.: Department of the Army, 24 November 1954.
10. TM 9-6067 Ordnance Maintenance Range Finders M12 and T41. Washington, DC: Department of the Army, 14 December 1954.
11. TM 9-6073 Ordnance Maintenance Superelevation Transmitter M22. Washington, DC: Department of the Army, 1 April 1954.
12. Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
13. Icks, COL (Ret.) Robert J. M47 Patton. Ed. Duncan Crow. Windsor, England: Profile Publications, Ltd., Dec 1972.
14. Sola, Samuel, Vincent Bobkowski, and Kara Crocker. Weapon Mounts for Secondary Armament. Santa Monica, CA: G. O. Noville & Associates, Inc., April 1957.
15. Miller, David. The Illustrated Directory of Tanks of the World. Osceola, WI: MBI Publishing Co., 2000.
16. 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. USA: University Press of Kentucky, 1999.
17. Foss, Chris. Modern Tanks. Glasgow: HarperCollins Publishers, 1995.
18. Hunnicutt, R.P. Sheridan: A History of the American Light Tank, volume 2. Navato, CA: Presidio Press, 1995. Reprinted with permission from Sheridan, R.P. Hunnicutt ©1994, available from Presidio Press, 505B San Martin Drive, Suite 160, Navato, CA 94945.
19. Hilmes, Rolf. Main Battle Tanks: Developments in Design since 1945. Trans. Richard Simpkin. London: Brassey's Defence Publishers, 1987.
20. TM 9-500 C3 Data Sheets for Ordnance Type Materiel. Washington, DC: Headquarters, Department of the Army, 12 October 1966.

Last updated 29 Sep 2026.
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