The Topf Mine, a completely non-metallic, waterproof, antitank mine, consists of a circular body filled with a 12 1/2-pound charge of TNT, a primer plug assembly, and an igniter. The top of the mine is flat, with a fixed pressure plate in the center slightly higher than the surface; a 4 1/2-inch circular recess located in the bottom takes the primer plug and igniter assembly. The outer casing is made of a hard pulp-like material covered with pitch. The mine rests on three glass studs; two of the studs secure a pasteboard carrying handle, while the third, which is sometimes larger than the two others, is used as a filler plug.
The primer plug assembly consists of a glass screw cap and a cylindrical wooden booster holder, the top of which has a deep threaded recess to take the Topf Mine Igniter. A subsidiary igniter socket in the glass cap leads to the booster charge, and is threaded to take a standard igniter.
The Topf Mine Igniter, which is made of glass, has no safety device. It comprises a cylindrical glass body 3 mm thick; a solid glass pressure head, hemispherical in shape and two small glass ampules, one of which contains sodium and potassium as a liquid alloy and the other ethyl nitrate. The ampules are held in position by a black celluloid disc. A thin bakelite detonator well is provided.
The mine is activated by a pressure of at least 330 pounds, which forces the pressure plate down onto the igniter head and thereby breaking the two glass ampules. A flash results, setting off the detonator, booster, and main charge. If a standard igniter is used, the mine must be laid upside down.
SPECIFICATIONS
| Diameter of mine | 12 1/2 ins. | |
| Height of mine | 5 1/2 ins. | |
| Weight (complete) | 20 lbs. | |
| Weight in crate | 29 lbs. | |
| Filling | TNT | |
| Weight of filling | 12 1/2 lbs. | |
| Firing pressure | 330 lbs. | |
| Height of igniter (including cap) | 3 1/2 ins. | |
| Diameter of igniter body | 1 1/2 ins. | |
| Shear pressure of igniter | 132 lbs. | |
| Overall height of primer plug assembly | 3.1 ins. | |
| Diameter of primer holder | 2 1/2 ins. | |
| Diameter of glass cap | 4.6 ins. |
German: p. 304.9 (May 1, 1945)