Topfmine
Encyclopedia
The Topfmines were a series of German
circular minimum metal
anti-tank blast mine
s that entered service with the German army in 1944, during the Second World War.
The mines used a case made of compressed wood-pulp, cardboard and tar
along with glass
plugs and components designed to be undetectable by Allied
mine detectors. Often the only metallic part of the mines was the detonator
.
To enable the mines to be found by friendly forces, the mines were painted with a black sandy substance called (camouflage
sand). Allied forces found that although the mines were undetectable by Allied mine detectors, German mine detectors could find the mines when they had been marked with Tarnsand. The secret of Tarnsand was maintained until after the end of the war, when it was discovered that it was a mildly radioactive substance and the German mine detectors incorporated a simple Geiger counter
.
waste. The SF 1 fuze was inserted into the underside of the mine and was placed inside a large glass plug which sealed the bottom of the mine. A secondary fuze well was provided on the bottom of this plug for installing anti-handling device
s. The SF 1 fuze was constructed of glass and wood and contained a detonator
and booster charge.
Pressure of approximately 330 pounds (150 kg) on the pressure plate caused the plate to shear off from the mine casing, collapsing down on the glass head of the pressure fuze. The glass head was driven downwards, crushing two glass vials of chemicals, which reacted together causing a flash, initiating the detonator, booster and finally the main charge of TNT.
Two versions of the mine were produced - a fully waterproofed version designated "To.Mi.A4531" and the normal "To.Mi.4531".
fuze
plug on the top. This design was very thin-walled and sympathetic detonation
could occur if the mines were planted closer together than seven feet (2 m).
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
circular minimum metal
Minimum metal mine
A minimum metal mine is a land mine that is designed to use the minimum amount of metal in its construction . Both minimum metal anti-tank and anti-personnel mines exist. Some designs contain almost no metal at all...
anti-tank blast mine
Anti-tank mine
An anti-tank mine, , is a type of land mine designed to damage or destroy vehicles including tanks and armored fighting vehicles....
s that entered service with the German army in 1944, during the Second World War.
The mines used a case made of compressed wood-pulp, cardboard and tar
Tar
Tar is modified pitch produced primarily from the wood and roots of pine by destructive distillation under pyrolysis. Production and trade in tar was a major contributor in the economies of Northern Europe and Colonial America. Its main use was in preserving wooden vessels against rot. The largest...
along with glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
plugs and components designed to be undetectable by Allied
Allies of World War II
The Allies of World War II were the countries that opposed the Axis powers during the Second World War . Former Axis states contributing to the Allied victory are not considered Allied states...
mine detectors. Often the only metallic part of the mines was the detonator
Detonator
A detonator is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the latter two being the most common....
.
To enable the mines to be found by friendly forces, the mines were painted with a black sandy substance called (camouflage
Military camouflage
Military camouflage is one of many means of deceiving an enemy. In practice, it is the application of colour and materials to battledress and military equipment to conceal them from visual observation. The French slang word camouflage came into common English usage during World War I when the...
sand). Allied forces found that although the mines were undetectable by Allied mine detectors, German mine detectors could find the mines when they had been marked with Tarnsand. The secret of Tarnsand was maintained until after the end of the war, when it was discovered that it was a mildly radioactive substance and the German mine detectors incorporated a simple Geiger counter
Geiger counter
A Geiger counter, also called a Geiger–Müller counter, is a type of particle detector that measures ionizing radiation. They detect the emission of nuclear radiation: alpha particles, beta particles or gamma rays. A Geiger counter detects radiation by ionization produced in a low-pressure gas in a...
.
Topfmine A
The Topfmine A had a flattened dome-shaped case with a raised flat circular pressure plate on the top surface surrounded by a circular shear groove. The case was normally made from pulped wood and cardboard mixed with tar for waterproofing. However, sometimes the case was made from bituminous coalBituminous coal
Bituminous coal or black coal is a relatively soft coal containing a tarlike substance called bitumen. It is of higher quality than lignite coal but of poorer quality than Anthracite...
waste. The SF 1 fuze was inserted into the underside of the mine and was placed inside a large glass plug which sealed the bottom of the mine. A secondary fuze well was provided on the bottom of this plug for installing anti-handling device
Anti-handling device
An anti-handling device is an attachment to or integral part of a landmine or other munition e.g. some fuze types found in air-dropped bombs such as the M83, cluster bombs and sea mines. It is specifically designed to prevent tampering. When the protected device is disturbed it detonates, killing...
s. The SF 1 fuze was constructed of glass and wood and contained a detonator
Detonator
A detonator is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the latter two being the most common....
and booster charge.
Pressure of approximately 330 pounds (150 kg) on the pressure plate caused the plate to shear off from the mine casing, collapsing down on the glass head of the pressure fuze. The glass head was driven downwards, crushing two glass vials of chemicals, which reacted together causing a flash, initiating the detonator, booster and finally the main charge of TNT.
Two versions of the mine were produced - a fully waterproofed version designated "To.Mi.A4531" and the normal "To.Mi.4531".
Topfmine B
The Topfmine B (To.Mi.B4531) was broadly similar to the "A" version, the principal difference being a smooth case without a raised pressure plate. This version instead had an internal shear groove to prevent water from working its way into the mine and possibly deactivating it.Topfmine C
The Topfmine C (To.Mi.C4531 or Pappmine) changed the design to an eight-sided flattened cylinder shape, with a central glassGlass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
plug on the top. This design was very thin-walled and sympathetic detonation
Sympathetic detonation
A sympathetic detonation , also called flash over, is a detonation, usually unintended, of an explosive charge by a nearby explosion. Sympathetic detonation is caused by a shock wave, or impact of primary or secondary blast fragments.The initiating explosive is called donor explosive, the initiated...
could occur if the mines were planted closer together than seven feet (2 m).
Specifications
| Topfmine A | Topfmine B | Topfmine C | |
| Diameter | 330 mm | 320 mm | 340 mm |
| Height | 140 mm | ||
| Weight | 9.5 kg | 10 kg | 9 kg |
| Explosive content | 6 kg | ||
| Operating pressure | 150 kilogram-forces (1.5 kN) | ||