20mm Self-propelled Air Defense Gun M163A1 Vulcan Air Defense System1-5

M163A1: General
Date of first acceptance (M163) 1969
Manufacturer General Electric Co. Crew
4 men:
  • Commander
  • Gunner in turret
  • Driver
  • Loader
M163A1: Dimensions
Combat weight 27,542lbs
Height 115"
Length 191.5"
Width over flotation pods 112.4"
Tread 85.0"
Ground clearance 16.1"
Ground pressure, zero penetration 8.7psi
M163A1: Armament
Type Mount Ammunition Traverse Max traverse rate Elevation Max elevation rate
20mm Cannon M168 M157 in turret 2,100 rounds 360°
75°/sec +80° to -5°
Night vision
Infrared periscope M19 for driver, night vision sight AN/TVS-2B or AN-TVS-5 for gunner
Ranging radar AN/VPS-2, computing sight M61
M163A1: Armor
Rolled 5083/5086 H32 aluminum armor
Location Thickness Angle from vertical
Upper front 1.5"
Lower front 1.5"
Upper sides 1.75"
Lower sides 1.25"
Rear 1.5"
Ramp 1.5"
Top 1.5"
Floor 1.125"
M163A1: Automotive
Engine General Motors 6V53; 6 cylinder, 2 cycle, vee diesel
Horsepower Gross: 212@2,800rpm Torque Gross: 492 ft-lb@1,300rpm Fuel capacity 95gal
Transmission Allison TX-100, 3 ranges forward, 1 reverse
Steering DS200 controlled differential, steering levers
Brakes Differential band
M163A1: Suspension
Type Road wheels Track return rollers
Torsion bar 5 individually sprung dual/track Flat track
Drive sprockets Idlers Shock absorbers
10-tooth front drive Dual adjustable at rear of track On first and last road wheels/track
M163A1: Track
Center guide, single pin, steel with detachable rubber pad
Width 15"
Pitch 6"
Shoes/track Left side: 63
Right side: 64
Ground contact length 105"
M163A1: Performance
Max level road speed 40mph
Max water speed 3.6mph
Max trench 66"
Max grade 60%
Max sideslope 30% Max vertical obstacle 24"
Min turning diameter 26'
Max fording depth Floats
Cruising range ~300mi, roads
~480km, roads

The M163 utilized a modified version of the US Air Force's M61 Vulcan six-barreled 20mm rotary cannon. It was installed in a turret on a modified M113A1 APC, designated as the M741. Modifications to the gun mount changed its designation to M157A1, and the vehicle's to M163A1. The M741 was similar to the M113A1, except that the M741 was equipped with an hydraulic suspension lock-out system to stabilize the M163 when firing. Since the M163 weighed so much more than the M113 APC, flotation cells were fitted to the sides of the vehicle, and a high-displacement trim vane was added to the front. When the powertrain modifications of the M113A2 APC were introduced to the M163, the carrier vehicle was redesignated as M741A1. The above data tables pertain to the carrier M741A1. The improved suspension of the M113A2 was not fitted since the M163's suspension was fitted with the lockout device. The M168 gun could fire at a high rate of 3,000 rounds per minute in 10-, 30-, 60-, or 100-rounds bursts, and it could also fire at a low rate of 1,000 rounds per minute. The gunner was to keep the trigger held until the end of the burst during high rate fire, and was not to fire less than a 10-round burst in low rate fire.

The Product Improved Vulcan Air Defense System (PIVADS), first accepted in 1984, was a kit developed by Lockheed Electronics Company which reduced the gunner's workload and improved the accuracy of the system. Hardware improvements included a digital microprocessor, director sight, low backlash azimuth drive system, and the ability to fire armor-piercing discarding sabot (APDS) ammunition. PIVADS provided its operators with automatic notification of system failures through its built-in test equipment (BITE). PIVADS's radar remained a range-only device.




  1. Hunnicutt, R.P. Bradley: A History of American Fighting and Support Vehicles. Navato, CA: Presidio Press, 1999. Reprinted with permission from Bradley, R.P. Hunnicutt ©1999, available from Presidio Press, 505B San Martin Drive, Suite 160, Navato, CA 94945.
  2. TM 9-2350-300-10 C4 Operation and Maintenance Manual (Crew) for Gun, Air Defense Artillery, Self-Propelled, 20-mm, M163A1 (2350-01-017-2113). Washington, DC: Headquarters, Department of the Army, 12 August 1985.
  3. Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
  4. Hogg, Ian V. The Greenhill Armoured Fighting Vehicles Data Book. London: Greenhill Books, 2000.
  5. Federation of American Scientists. "M163 Vulcan Air Defense System." DOD 101. 29 May 2000. 23 May 2001 <http://www.fas.org/man/dod-101/sys/land/m163.htm>. DOD 101
Last updated 9 Jan 2023.
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