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Great Britain's Medium Tank Mk I

Photos

Medium Mk I:
Great Britain's Vickers Medium Mk I
©IWM
Medium Mk I CS with a 15 pdr mortar:
Great Britain's Vickers Medium Mk I CS with a 15 pdr mortar
Royal Armored Corps Tank Museum
Medium Mk I with a Ricardo Diesel engine:
Great Britain's Vickers Medium Mk I with a Ricardo Diesel engine
Royal Armored Corps Tank Museum

Design

In 1924 the former Vickers Light Tank Mk I was redesignated the Medium Tank Mk I.1,2 The Mark I Medium Tank was the first tank designed after World War I.2

Construction

The Medium Tank Mk I was constructed by riveting armored plates together.1

Engine Compartment

The engine was placed at the front of the Medium Tank Mk I, next to the driver.1 Between them was a double asbestos and steel partition.1

The Mk IA had plates that folded back.1

Engine

The engine used steel cylinders with aluminum casings.1 Air was drawn over oil cooling pipes to cool the engine.1 There was 13 1/2 gallons of oil used throughout the engine.1 The Mk I's engine had to be started from the inside.1

The engines were notoriously hard to start up and in one instance after a severe frost it took six hours to start three tanks.1

The Mk IA had an access opening that allowed for the engine to be started from outside the tank.1

Turret

The Mark I Medium Tank was the first British tank to have a turret.2

The turret of the Mk IA* had a counterweight installed to balance the command post that was installed, also known as the "Bishop's Mitre."1 The gunner didn't have a seat and had to coordinate his right hand, working in the horizontal, with his left, working in the vertical.1

Prototype

In 1923 the prototype of the Medium Mk I was sent to Bovington for testing.1

Production

  • Medium Tank Mk I: 301
    • Manufacturer: Vickers-Armstrong1
  • Medium Tank Mk IA: 501
    • Manufacturer: Vickers-Armstrong1

Variants

  • Vickers Medium Tank Mk I:
  • Mark IA Medium Tank: The turret had a beveled plate for an antiaircraft machine gun.1
  • Mark IA* Medium Tank: Introduced coaxial machine gun in the turret.1

Usage

In 1938 the Mark I Medium Tank was removed from active service and moved into a training role.2

Specifications

  Medium Mk I
Crew Commander, driver, radio operator, gunners (2)2
51,2
Physical Characteristics  
Weight 11.7 tons1, 12 tons2
12,192 kg2
Length 17' 6"1,2
5.33 m2
Height 9' 3"1,2
2.82 m2
Width 9' 1.5"1, 9' 2"2
2.79 m2
Width over tracks  
Ground clearance  
Ground contact length  
Ground pressure 30 - 40 psi1
Turret ring diameter  
Armament  
Main 3 pdr1
3 pdr (47 mm / 1.85")2
Secondary  
MG 3: .303 Hotchkiss MG1
2: 7.7 mm / 0.303" Vickers MG2
4: 7.7 mm / 0.303" Hotchkiss MG2
MG - turret rear 1: .303 Hotchkiss MG1
MG - side, behind escape doors 2: .303 Vickers MG1
Side arms  
Quantity  
Main  
Secondary  
MG  
Side arms  
Armor Thickness (mm) 6 - 251, 82
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) Armstrong Siddeley1,2
Bore / stroke  
Cooling Air1,2
Cylinders V-81,2
Capacity  
Net HP 901,2
Power to weight ratio  
Compression ratio  
Transmission (Type)  
Steering  
Steering ratio  
Starter  
Electrical system 12 volt1
Ignition  
Fuel (Type) Petrol1,2
Octane  
Capacity  
Road consumption  
Cross country consumption  
Performance  
Traverse  
Speed - Road 15 mph1,2
24 kph2
Speed - Cross Country  
Range - Road 120 miles1, 150 miles2
241 km2
Range - Cross Country  
Turning radius  
Elevation limits  
Fording depth  
Trench crossing  
Vertical obstacle  
Climbing ability  
Suspension (Type) Spring2
Wheels each side  
Return rollers each side 41
Tracks (Type) No. 31
Length  
Width 13"1
Diameter  
Number of links 661
Pitch  
Tire tread  
Track centers/tread  
  Medium Mk IA
Crew 51
Physical Characteristics  
Weight 11.9 tons1
Length 17' 6"1
Height 8' 10.5"1
Width 9' 1.5"1
Width over tracks  
Ground clearance  
Ground contact length  
Ground pressure  
Turret ring diameter  
Armament  
Main 3 pdr1
Secondary  
MG 4: .303 Hotchkiss MG1
1: .303 Vickers MG1
MG - antiaircraft 1: .303 Vickers MG1
Side arms  
Quantity  
Main  
Secondary  
MG  
Side arms  
Armor Thickness (mm) 6 - 251
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) Armstrong Siddeley1
Bore / stroke  
Cooling Air1
Cylinders V 81
Capacity  
Net HP 901
Power to weight ratio  
Compression ratio  
Transmission (Type)  
Steering  
Steering ratio  
Starter  
Electrical system  
Ignition  
Fuel (Type)  
Octane  
Capacity  
Road consumption  
Cross country consumption  
Performance  
Traverse  
Speed - Road 15 mph1
Speed - Cross Country  
Range - Road 120 miles1
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  
  Medium Mk IA*
Crew 51
Physical Characteristics  
Weight 11.9 tons1, 12.1 tons1
Length 17' 6"1
Height 9' 10.5"1
Width 9' 1.5"1
Width over tracks  
Ground clearance  
Ground contact length  
Ground pressure  
Turret ring diameter  
Armament  
Main 3 pdr1
Secondary  
MG 2: .303 Vickers MG1
MG - coaxial 1: .303 Vickers MG1
Side arms  
Quantity  
Main  
Secondary  
MG  
Side arms  
Armor Thickness (mm) 6 - 251
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) Armstrong Siddeley1
Bore / stroke  
Cooling Air1
Cylinders V 81
Capacity  
Net HP 901
Power to weight ratio  
Compression ratio  
Transmission (Type)  
Steering  
Steering ratio  
Starter  
Electrical system  
Ignition  
Fuel (Type)  
Octane  
Capacity  
Road consumption  
Cross country consumption  
Performance  
Traverse  
Speed - Road 15 mph1
Speed - Cross Country  
Range - Road 120 miles1
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:

  1. AFV #12 Medium Marks I - III, Major-General N. W. Duncan
  2. World War I and II Tanks, George Forty, 2012
20th Century American Military History Crucial Site