Bob Semple tank
Encyclopedia
The Bob Semple tank was a tank
designed by New Zealand
Minister of Works Bob Semple
during World War II
. Originating out of the need to build military hardware from available materials, the tank was built from corrugated iron on a tractor base. Designed and built without formal plans or blueprints, it had numerous design flaws and practical difficulties, and was never put into mass production or used in combat. Despite this, it has become something of an icon of the New Zealand 'do it yourself' mentality.
"Six Ton Tractor Tank" a 1937 vehicle constructed of an amoured box on a Caterpillar Model 35 chassis which had been sold to Afghanistan and China was suggested.
New Zealand had built some improvised armoured trucks and unable to get any tracked carriers
from Australia were building their own with armour plate imported from Australia.
After the Fall of France in mid-1940, and the loss of most British tanks there, there was no likelihood of production being spared for New Zealand. Rather than obtain the armoured superstructures from the US, it was felt they could produce their own using local materials and resources.
It was decided that a ‘tractor-tank’ would be an adequate design, as if the need for defense arose, a large tank superstructure could be bolted upon a tractor base within a few hours, allowing for quick transformation and deployment of the tanks.
The first (mild steel) prototype was built on Caterpillar D8
, a type which was readily available. A lack of weapons meant that it was equipped with seven Bren machine guns - two in the sides, three facing the front, one in the turret and one at the rear. The vehicle was very tall at 12 ft (3.5 m) and performance was poor.
Due to the lack of armour plate, corrugated (manganese) plating was used in the expectation it would deflect bullets. The crew of eight included one gunner who had to lie on a mattress on top of the engine to fire his Bren gun.
The tanks were constructed without the use of any formal plans or blueprints. Working from an American postcard depicting the conversion of a tractors to a ‘tractor-tank’, Bob Semple and TG Beck (Christchurch District Works Engineer), improvised the design of the tanks. Using resources available to Bob Semple as Minister of Public Works, the tanks were quickly produced in their Christchurch
workshops.
The intention was to disperse the hulls at locations ready in case of a Japanese invasion at which point they would be mounted on tractors for use. The idea was discarded after the tanks attracted public ridicule.
, dismantled, and restored to their previous state as tractors.
Built during the war hysteria, these tanks were a civilian effort to design and create a means to protect New Zealand. In doing so, the tanks arguably showed a self reliance and vigor in the nation, uplifting their morale. Used mainly for processions, these tanks were warmly received in Christchurch, Auckland and many other parts of the country.
Tank
A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...
designed by New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
Minister of Works Bob Semple
Bob Semple
Robert "Bob" Semple was a union leader and later Minister of Public Works for the first Labour Government of New Zealand....
during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. Originating out of the need to build military hardware from available materials, the tank was built from corrugated iron on a tractor base. Designed and built without formal plans or blueprints, it had numerous design flaws and practical difficulties, and was never put into mass production or used in combat. Despite this, it has become something of an icon of the New Zealand 'do it yourself' mentality.
Design and construction
New Zealand, like its neighbour Australia, had no indigenous armoured fighting vehicle industry. It was expected that armoured fighting vehicles would be provided from the UK. Australia, and New Zealand did have some heavy industry that could be turned to the production of armour and armoured vehicles but little had been done. The idea of mechanising the New Zealand Army had been suggested before the war but there hadn't been much progress. The use of the US DisstonDisston Saw Works
Disston Saw Works was one of the better known and highly regarded manufacturers of handsaws in the United States. A much evolved version of this company is currently active in Philadelphia and known as Disston Precision.-History:...
"Six Ton Tractor Tank" a 1937 vehicle constructed of an amoured box on a Caterpillar Model 35 chassis which had been sold to Afghanistan and China was suggested.
New Zealand had built some improvised armoured trucks and unable to get any tracked carriers
Universal Carrier
The Universal Carrier, also known as the Bren Gun Carrier is a common name describing a family of light armoured tracked vehicles built by Vickers-Armstrong. Produced between 1934 and 1960, the vehicle was used widely by British Commonwealth forces during the Second World War...
from Australia were building their own with armour plate imported from Australia.
After the Fall of France in mid-1940, and the loss of most British tanks there, there was no likelihood of production being spared for New Zealand. Rather than obtain the armoured superstructures from the US, it was felt they could produce their own using local materials and resources.
It was decided that a ‘tractor-tank’ would be an adequate design, as if the need for defense arose, a large tank superstructure could be bolted upon a tractor base within a few hours, allowing for quick transformation and deployment of the tanks.
The first (mild steel) prototype was built on Caterpillar D8
Caterpillar D8
The Caterpillar D8 is a large track-type tractor designed and manufactured by Caterpillar.Though it comes in many configurations it is usually sold as a bulldozer equipped with a detachable large blade and a rear ripper attachment.-History:...
, a type which was readily available. A lack of weapons meant that it was equipped with seven Bren machine guns - two in the sides, three facing the front, one in the turret and one at the rear. The vehicle was very tall at 12 ft (3.5 m) and performance was poor.
Due to the lack of armour plate, corrugated (manganese) plating was used in the expectation it would deflect bullets. The crew of eight included one gunner who had to lie on a mattress on top of the engine to fire his Bren gun.
The tanks were constructed without the use of any formal plans or blueprints. Working from an American postcard depicting the conversion of a tractors to a ‘tractor-tank’, Bob Semple and TG Beck (Christchurch District Works Engineer), improvised the design of the tanks. Using resources available to Bob Semple as Minister of Public Works, the tanks were quickly produced in their Christchurch
Christchurch
Christchurch is the largest city in the South Island of New Zealand, and the country's second-largest urban area after Auckland. It lies one third of the way down the South Island's east coast, just north of Banks Peninsula which itself, since 2006, lies within the formal limits of...
workshops.
The intention was to disperse the hulls at locations ready in case of a Japanese invasion at which point they would be mounted on tractors for use. The idea was discarded after the tanks attracted public ridicule.
Handling and performance
Due to the limitations of requirements and resources, the tank was a functional failure. By using a large tractor as a base, and bolting on a hastily designed and poorly constructed tank superstructure, the resultant tanks were inadequately armored, extremely heavy (20-25 ton), unstable, restricted by tractor gearing to slow speeds, and had to stop to change gears. Furthermore, due to the shape of the underlying tractor and undue vibrations, shooting from the tank was both difficult and inevitably inaccurate.Final result
In the end, due to their impracticality, the tanks were rejected for use by the New Zealand ArmyNew Zealand Army
The New Zealand Army , is the land component of the New Zealand Defence Force and comprises around 4,500 Regular Force personnel, 2,000 Territorial Force personnel and 500 civilians. Formerly the New Zealand Military Forces, the current name was adopted around 1946...
, dismantled, and restored to their previous state as tractors.
Built during the war hysteria, these tanks were a civilian effort to design and create a means to protect New Zealand. In doing so, the tanks arguably showed a self reliance and vigor in the nation, uplifting their morale. Used mainly for processions, these tanks were warmly received in Christchurch, Auckland and many other parts of the country.