Heavy Tank Mark VIII1-12

Mk. VIII: General
Date of first acceptance January 1920 Total acceptances 100
Manufacturer Rock Island Arsenal Crew
11 men:
  • Commander in turret cupola
  • Six-pounder gunner in each sponson
  • Six-pounder loader in each sponson
  • Four machine gunners
  • Driver in hull front center
  • Mechanic in hull rear
Mk. VIII: Dimensions
Combat weight 86,900lbs
Height 123.0"
Length 410.5"
Width over sponsons 144.0"
Tread 69.5"
Ground clearance 20.8"
Ground pressure, zero penetration 16.1psi
Mk. VIII: Armament
Type Mount Ammunition Traverse Elevation
Hotchkiss 6 pounder Mk. II Gun Side sponson 208 rounds Manual Manual
.30cal M1919 Browning tank MG Ball mount in each side door 15,100 rounds Manual Manual
Two .30cal M1919 Browning tank MGs Ball mounts in turret front Manual Manual
.30cal M1919 Browning tank MG Ball mount in turret rear Manual Manual
Aiming equipment
Telescope 15, Mark I for 6 pounder gunners
Mk. VIII: Armor
Rolled face-hardened steel plate
Location Thickness
Side plates 0.47"
Back plates, rear of gasoline tank 0.63"
Front wing plates 0.39"
Outside skirting plates 0.39"
Front sloping plate 0.47"
Front diaphragm plate 0.47"
Main turret side plates 0.63"
Main turret top plates 0.2"
Driver's turret plates 0.2"
Hemispherical turrets in doors and main turret 0.55"
Top plating of lookout turret 0.2"
Side lookout plating 0.63"
Sponson floor plates 0.3"
Sponson roof plates 0.2"
Sponson top shield 0.3"
Sponson bottom shield 0.3"
Sponson side plates 0.47"
Forward sponson floor plates 0.47"
Aft sponson floor plates 0.2"
Roof plate abaft turret 0.2"
Roof plate over engine 0.2"
Roof plate over gasoline tank 0.39"
Roof plate over driver 0.2"
Doors 0.47"
Mk. VIII: Automotive
Engine Liberty 12; 12 cylinder, 4 cycle, 45° vee gasoline
Horsepower Gross: 338@1,400rpm Fuel capacity 240gal
Transmission Epicyclic, 2 speeds forward, 2 reverse
Steering Epicyclic, levers
Brakes Mechanical, external contracting
Mk. VIII: Suspension
Type Road wheels Track return rollers
Rigid 14 lower track rollers with spacers and spring plates/track;
15 lower track rollers without spacers or spring plates/track
1 top track return roller/track
Drive sprockets Idlers Shock absorbers
35-tooth rear drive Adjustable at front of track None
Mk. VIII: Track
Continuous linked dished armor plate
Width 26.5"
Pitch 11.154"
Shoes/track 78 Ground contact length, zero penetration 102"
Mk. VIII: Performance
Max level road speed 5.5mph
Max trench 192"
Max grade 84% Max vertical obstacle 54"
Min turning diameter 40.5'
Max fording depth 34"
Cruising range ~40mi

The Mark VIII, also known as the Liberty, International, or Anglo-American tank, was a continuance of the British rhomboid landship line of tanks. The plans were for the Mark VIII to be assembled in France using American automotive components and British armament and armor. The end of the World War I spelled the end of the manufacturing consortium, but the US pressed on to construct 100 vehicles with its own engine and armament. The tank had a nonrotating main turret on the hull with mounts for three machine guns, and atop this turret was the commander's lookout turret. The 6 pounder weapons had a caliber of 57mm, and the sponsons in which they were mounted were hinged so that the rear could be pivoted into the hull to reduce shipping width. The 6 pounders were then drawn in so that the 81" (270cm) loading gauge could be obtained. Likewise, the lookout turret was lowered flush with the main turret roof when shipping the tank. The tracks were chain-driven in that a bicycle-like chain from the transmission spun a roller sprocket, and this roller sprocket drove the track drive sprocket, which was at the time referred to as a road track driving wheel. The tank's tracks were made of armor plate which was 8mm (0.3") thick. The vehicle's ground pressure dropped to 13.85psi (.9723kg/cm²) at 1" (2.5cm) of penetration and continued down to 4.26psi (.299kg/cm²) at 15" (38cm) penetration. The two types of road track rollers were mounted alternately; the spring plates were spacers to hold the rollers in the proper position on their axle shafts. The US had removed the Mark VIII from service by 1932, but some of the tanks were offered to Canada for use as training vehicles after the start of World War II.




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Last updated 6 Dec 2023.
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