DATA:

DESCRIPTION. The main parts of the Topf mine are the mine body, the primer plug as-sembly and the igniter. (See fig. 235.)

Mine Body. The mine body is a hollow cylindrical disk of plastic material filled with H.E. Its top face is fomred as a circular pressure plate surrounded by a shear groove. The cylin-drical recess in the center of the mine body accommodates the primer plug. The carrying handle is fixed to the mine body by two glass screws. Another glass screw in the mine bottom acts as a filler plug.

Primer Plug Assembly. The primer plug assembly consists of a glass screw cap and the cylindrical igniter seating, made of compressed bituminous cardboard material. The top face of the igniter seating bears a deep pocket with an inside screw thread to accommo-date the Topf mine igniter. The remaining space between the glass screw cap and the igniter seating is filled with the primer charge. In addition to the pocket for the Topf mine igniter, there is a subsidiary igniter socket leading into the primer charge from the bottom through a hole in the glass srew cap. This subsidary igniter socket has a standard igniter screw thread, and a thin bakelite detonator pocket to protect it against moisture. A cir-cular ridge, moulded on the side of the glass screw cap nearst to the mine body presses against a rubber washer when the primer plug assembly is fitted into the mine.

Igniter. The igniter is an entirely nonmetallic pressure igniter without a safety device, and functions on chemical-mechanical action. It is used, together with a nonmetalic de-tonator, as the main igniter for the Topf mine.

The main parts of the igniter are a hollow cylindrical glass igniter body, and a hemispheri-cal pressure head fitting into the igniter body.

Inside the igniter body there is a circular celluloid disk with two small spherical glass cap-sules, containing liquid chemicals, fixed on to it by means of an adhesive. The lower part of the igniter body has two male screws threads, the larger one fitting into the igniter seating, while a protective detonator pocket of plastic material is held by the smaller screw thread. A circular shear ridge halfway up on the pressure head rests on the top rim of the igniter body and so holds the head in position with its flat portion slightly pro-jecting into the igniter body, just above the two glass capsules.

OPERATION. Under a load of  least 150 kg (330 pounds) the pressure plate of the Topf mine shears along its shear groove and thus comes to rest on the pressure head of the igniter. This in turn gives way by the severing of its shear ridge and thus smashes the two small chemical glass capsules inside the igniter body. The chemicals therein make contact with each other causing a flash which sets off the detonator, and so the mine.

Figure 235 – Topf Mine A – Antitank