With Japan becoming a threat in the Pacific and England occupied by Germany, the Australian Ministry of Munitions started to consider building their own tanks in early June 1940.
This was to be a major undertaking by the Australians as they had never even built their own automobiles.
A. Chamberlain, was an engineer that was sent to the United States to study tank production. He was joined by Colonel W. D. Watson, who was an advisor from England. They both studied the M3 Medium.
In November the Australian General Staff developed the requirements for a tank. It was to have a 2-pdr (40 mm) gun and two 7.7 mm (0.303") machine guns. The tank was also required to go 30 mph and have at least 50 mm of armor. It was to use as many of the same components as the American M3 Light Tank. The engine was to be three Cadillac automobile engines joined together. Cast armor was also a requirement.
It had rubber-block suspension with horizontal volute bogies similar to the French Hotchkiss.
The centered hull machine gun had a large armored sleeve.
In the front the driver sat on the right side with the hull gunner on the left. Between them sat the gearbox and the Vickers .303 machine gun that was water cooled.
The middle compartment contained the turret, which contained the commander on the left, the loader / radio operator on the right, and the gunner in front of the commander.
The rear compartment contained the frame which held the three Cadillac 75 engines. The fuel and radiator was also located in the rear compartment.
As firms producing rolled armored plates were committed, it was decided to try to make the hull from a solid cast. Other experiments involved trying to make strong enough armor from metals available in Australia.
Early hopes to use the Guiberson diesel engine were dashed and the Cadillac automobile engine was selected. Three engines were combined.
Australia had hoped to make a copy of the M3 Medium's gearbox, but industry in Australia just didn't have the tooling to make them properly. Chamberlain returned in May 1941 from the United States proposing the design of what would become the AC 2. The AC 2 would use imported transmissions that were used in heavy trucks. However, with events in the Pacific rapidly changing, the AC 2 program was cancelled in September 1941 by the Minister for the Army.
With design changes it became possible for the manufacture of the gearbox, for the AC 1, in Australia.
The radio was a Wireless Set No. 19 Mk 2.
A wooden prototype was built in early 1941 and in October the first hull had been cast. The first three pilot models were completed in January 1942, only 22 months after the original General Staff specifications.
The AC 1 was originally designed to be capable of carrying the 6 pdr, but supplies were unavailable due to the British Army needing them in North Africa. It was decided to install an Australian produced 25 pdr. The AC 3 was first test fired at Williamstown, Victoria, on June 29, 1942.
The estimated 2,000 would be needed and first ones to be ready by July 1941 and 70 per month being produced.
The Chullona Tank Assembly Shops in New South Wales would produce the tanks. Production started in August 1942 with a total of 66 being built. A new factory was built, but with America able to supply enough tanks for Australia's use production ceased and the tank was used for training.
Used only for training.
Crew | 5 |
Physical Characteristics | |
Weight | 62,720 lb, 62,732 lb 28 tons 28,489 kg |
Length | 20' 9" 6.4 m |
Height | 9' 1", 8' 5" 2.59 m |
Width | 8' 2", 8' 5", 9' 1" 2.8 m |
Width over tracks | |
Ground clearance | 1' 3" |
Ground contact length | |
Ground pressure | |
Turret ring diameter | |
Armament | |
Main | 40 mm (2 pdr) |
Secondary | |
MG | 2: 7.62 mm MG |
MG - coaxial | 7.7 mm |
MG - hull | 7.7 mm |
Side arms | |
Quantity | |
Main | 130 |
Secondary | |
MG | 4,250 |
Side arms | |
Armor Thickness (mm) | 65 |
Hull Front, Upper | |
Hull Front, Lower | |
Hull Sides, Upper | |
Hull Sides, Lower | |
Hull Rear | |
Hull Top | |
Hull Bottom | |
Turret Front | |
Turret Sides | |
Turret Rear | |
Turret Top | |
Engine (Make / Model) | 3: Cadillac |
Bore / stroke | |
Cooling | |
Cylinders | 8 x 3 |
Capacity | |
Net HP | 117 x 3 |
Power to weight ratio | |
Compression ratio | |
Transmission (Type) | |
Steering | |
Steering ratio | |
Starter | |
Electrical system | |
Ignition | |
Fuel (Type) | Gasoline |
Octane | |
Quantity | |
Road consumption | |
Cross country consumption | |
Performance | |
Traverse | |
Speed - Road | 20 mph, 30 mph 48 kph |
Speed - Cross Country | |
Range - Road | 200 miles, 198 miles 319 km |
Range - Cross Country | |
Turning radius | |
Elevation limits | |
Fording depth | 3' 11.5" |
Trench crossing | 8' |
Vertical obstacle | |
Climbing ability | |
Suspension (Type) | Volute Scissors |
Wheels each side | 6x2 |
Return rollers each side | 3 |
Tracks (Type) | |
Length | |
Width | 16.5" |
Diameter | |
Number of links | |
Pitch | |
Tire tread | |
Track centers/tread |
Australian Cruiser Mk I, AC 1 | |
---|---|
Crew | Commander, driver, hull gunner, gunner, loader 5 |
Physical Characteristics | |
Weight | 62,720 lb 28 tons 28,450 kg, 28,489 kg |
Length | 20' 9" 6.32 m, 6.325 m |
Height | 8' 4.75", 8' 5" 2.56 m, 2.57 m |
Width | 9' 1" 2.768 m, 2.77 m |
Width over tracks | |
Ground clearance | |
Ground contact length | |
Ground pressure | 13.4 psi |
Turret ring diameter | 54" |
Armament | |
Main | 1: 2 pdr. OQF 1: 2 pdr / 40 mm |
Secondary | |
MG | 2: Vickers .303 cal MG 2: Vickers MG 1: 7.62 mm MG 2: 7.7 mm MG |
MG - coaxial | Vickers .303 MG |
MG - hull | Vickers .303 MG |
Side arms | |
Quantity | |
Main | 130 |
Secondary | |
MG | 4,250 |
Side arms | |
Armor Thickness (mm) | 25, 65, 25 - 26, 25 - 65 |
Hull Front, Upper | 65 |
Hull Front, Lower | |
Hull Sides, Upper | 45 |
Hull Sides, Lower | |
Hull Rear | 45 |
Hull Top | 25 |
Hull Bottom | |
Turret Front | 65 |
Turret Sides | 65 |
Turret Rear | 65 |
Turret Top | 25 |
Engine (Make / Model) | 3: Cadillac 3: Cadillac 75 |
Bore / stroke | |
Cooling | Water |
Cylinders | V-8 |
Capacity | |
Net HP | 117 each 330, 350@3,050 rpm |
Power to weight ratio | 12:1 hp/ton |
Compression ratio | |
Transmission (Type) | |
Steering | |
Steering ratio | |
Starter | |
Electrical system | Lights: 6 volt Radio: 12 volt Turret traverse: 40 volt |
Ignition | |
Fuel (Type) | Gasoline |
Octane | |
Quantity | 140 gallons internal 44 gallon jettisonable tank |
Road consumption | |
Cross country consumption | |
Performance | |
Traverse | 360° , 18°/second |
Speed - Road | 20 mph, 30 mph 48.2 kph, 48.3 kph |
Speed - Cross Country | 20 mph |
Range - Road | 198 miles, 200 miles 319 km, 322 km |
Range - Cross Country | |
Turning radius | |
Elevation limits | |
Fording depth | 4' |
Trench crossing | 8', 9' 6" 2.438 m |
Vertical obstacle | 2' |
Climbing ability | |
Suspension (Type) | Horizontal volute spring |
Wheels each side | 3x2 sets |
Return rollers each side | 3 |
Tracks (Type) | Rubber Steel |
Length | |
Width | 16.5" |
Diameter | |
Number of links | Rubber: 86 Steel: 129 |
Pitch | Rubber: 6" Steel: 4" |
Tire tread | |
Track centers/tread | 7' 6.5" |
AC 3 | |
---|---|
Crew | Commander, driver, gunner, loader 4, 5 |
Physical Characteristics | |
Weight | 62,720 lb |
Length | 20' 9" |
Height | 8' 5" |
Width | 9' 1" |
Width over tracks | |
Ground clearance | |
Ground contact length | |
Ground pressure | |
Turret ring diameter | 64" |
Armament | |
Main | 25 pdr. 25 pdr. howitzer |
Secondary | |
MG | Vickers .303 cal MG |
MG - coaxial | Vickers .303 cal MG |
Side arms | |
Quantity | |
Main | |
Secondary | |
MG | |
Side arms | |
Armor Thickness (mm) | 25 - 65 25, 65 |
Hull Front, Upper | |
Hull Front, Lower | |
Hull Sides, Upper | |
Hull Sides, Lower | |
Hull Rear | |
Hull Top | |
Hull Bottom | |
Turret Front | |
Turret Sides | |
Turret Rear | |
Turret Top | |
Engine (Make / Model) | 3: Cadillac 3: Perrier-Cadillac 41-75 |
Bore / stroke | |
Cooling | |
Cylinders | V-8 |
Capacity | |
Net HP | 397 |
Power to weight ratio | |
Compression ratio | |
Transmission (Type) | |
Steering | |
Steering ratio | |
Starter | |
Electrical system | |
Ignition | |
Fuel (Type) | Gasoline |
Octane | |
Quantity | |
Road consumption | |
Cross country consumption | |
Performance | |
Traverse | 360° |
Speed - Road | 30 mph |
Speed - Cross Country | 20 mph |
Range - Road | 229 miles |
Range - Cross Country | |
Turning radius | |
Elevation limits | |
Fording depth | 4' |
Trench crossing | 9' 6" |
Vertical obstacle | 4' |
Climbing ability | |
Suspension (Type) | |
Wheels each side | |
Return rollers each side | |
Tracks (Type) | |
Length | |
Width | 16.5" |
Diameter | |
Number of links | |
Pitch | |
Tire tread | |
Track centers/tread | 7' 6.5" |
AC 4 | |
---|---|
Crew | |
Physical Characteristics | |
Weight | 31 tons |
Length | |
Height | |
Width | |
Width over tracks | |
Ground clearance | |
Ground contact length | |
Ground pressure | |
Turret ring diameter | 70" |
Armament | |
Main | 17 pdr. |
Secondary | |
MG | |
MG - coaxial | Vickers .303 cal MG |
Side arms | |
Quantity | |
Main | |
Secondary | |
MG | |
Side arms | |
Armor Thickness (mm) | |
Hull Front, Upper | |
Hull Front, Lower | |
Hull Sides, Upper | |
Hull Sides, Lower | |
Hull Rear | |
Hull Top | |
Hull Bottom | |
Turret Front | |
Turret Sides | |
Turret Rear | |
Turret Top | |
Engine (Make / Model) | 4: Gipsy Major |
Bore / stroke | |
Cooling | |
Cylinders | |
Capacity | |
Net HP | |
Power to weight ratio | |
Compression ratio | |
Transmission (Type) | |
Steering | |
Steering ratio | |
Starter | |
Electrical system | |
Ignition | |
Fuel (Type) | |
Octane | |
Quantity | |
Road consumption | |
Cross country consumption | |
Performance | |
Traverse | |
Speed - Road | |
Speed - Cross Country | |
Range - Road | |
Range - Cross Country | |
Turning radius | |
Elevation limits | |
Fording depth | |
Trench crossing | |
Vertical obstacle | |
Climbing ability | |
Suspension (Type) | |
Wheels each side | |
Return rollers each side | |
Tracks (Type) | |
Length | |
Width | |
Diameter | |
Number of links | |
Pitch | |
Tire tread | |
Track centers/tread |
Sources: