75. Topfmines (To.Mi.)

a. General. The nonmetallic antitank Topfmine (pot mine) first appeared in combat in early 1945. It was produced to prevent detection by electronic mine detectors. The de-tonator had the only metal in the entire assembled mine althrough a card-board detona-tor was often used.

b. Description.

(1)

Topfmine A. The antitank Topfmine A (fig. 85) is 12 1/2 inches in diameter and 5 1/2 inches high. It weighs a total of about 21.25 pounds, including a main charge of about 13 pounds of explosive. The case is made of pressed wood pulp, card-board, and tar. In some mines, the case is made of pressed bituminous coal waste, 1 inch thick. A thick, circular pressure plate is joined to the case at the shear groo-ve. The Topfmine fuze SF 1 (par. 30), with the wooden fuze-and-booster-charge holder that connects to the booster charge, is fitted into the mine through a hole in the bottom. This hole is closed with the large, circular glass fuze-assembly plug. The glass fuze-assembly plug contains an activating-fuze well, which is positioned slightly off center. A smaller, hexagonal glass filler plug in the bottom of the mine closes the filler hole for the main charge. A cardboard handle is attached to the bottom of the mine by two glass cap screws. Either a snap fuze or a tilt fuze (fig. 86) can be used instead of the Topfmine fuze SF 1. The mine was designated the To.Mi. A4531 by the Germans, the letter A indicating that the mine was water-proofed. Mines not waterproofed were marked To.Mi. 4531.

(2)

Topfmine B. The Topfmine B (fig. 87) differs from type A only in that it is curved over the top, and that the shear groove of the pressure plate is inside the mine to prevent water from accumulating in the shear groove.

(3)

Topfmine C (Pappmine). The Topfmine C, or Pappmine (papermine), (fig. 88) has a flat top and bottom, and is provided with a fuze well in the top of the mine to re-ceive the fuze. The fuze well is closed with a glass pressure plug.

Figure 85. Topfmine A.

c. Employment. These mines are employed as antitank mines. The Germans laid this mine with a black, metallic sandy substance called Tarnsand sprinkled on the mine; the mine was then covered with not more than 2 inches of dirt or soil. Tarnsand can be detected with the Stuttgart 43 detector (par. 133) if it is desired to retake the mine field. In aeras being abandoned, Tarnsand is not used.

Note. The SCR-625 detector will not detect this mine.

d. Functioning.

(1)

With the Topfmine fuze SF 1. A pressure of at least 330 pounds on the pressure plate shears off the pressure plate at the shear groove and transfers the pressure to the glass pressure head of the fuze. (The Topfmine C, or Pappmine, has a thin cardboard pressure plate with a glass pressure plug in the center instead of a thick pressure plate with a shear groove). The pressure on the glass pressure head shears off the glass rim of the pressure head at the shear groove, allowing the pressure head to crush the two glass vials of chemicals. The chemicals react to cause a flame which stes off the detonator, the booster charge, and the main charge.

(2)

With a snap fuze or a tilt fuze. A sideward pressure exerted on the fuze actuates it and fires the mine.

Figure 86. Topfmine A fitted with a snap fuze.

e. Installing and Arming Topfmine A and B.

(1)

With the Topfmine fuze SF 1.

(a)

Unscrew the glass fuze-assembly plug from the mine.

(b)

Screw the fuze, with detonator, into the wooden fuze-and-booster-charge holder.

(c)

Frimly screw the glass fuze-assembly plug into the bottom of the mine case, making sure that the rubber washer and its groove in the mine case are per-fectly clean.

(d)

Lay the mine in a hole with the pressure plate up. Do not use more than an 2-inch camouflage layer over the pressure plate. Keep a distance of 7 feet bet-ween mines to reduce the possibility of sympathetic detonation.

(2)

With a snap fuze or a tilt fuze.

(a)

Turn the mine upside-down and place it in the hole.

(b)

Remove the plastic activating fuze well plug and screw a snap fuze or a tilt fuze, with detonator, into the activating fuze well in the glass fuze-assembly plug.

(c)

Arm the fuze in accordance with instructions outlined in chapter 5.

f. Installing and Arming Topfmine C.

(1)

With the Topfmine fuze SF 1.

(a)

Unscrew the glass pressure plug from the mine.

(b)

Screw the fuze, with detonator, into the booster charge.

(c)

Firmly screw the glass pressure plug into the mine case.

(d)

Lay the mine in a hole with the glass pressure plug up. Do not use more than a 2-inch camouflage layer over the glass pressure plug. Keep a distande of 7 feet between mines to reduce the possibilty of sympathetic detonation.

(2)

With a snap fuze or a tilt fuze.

(a)

Unscrew the glass pressure plug from the mine.

(b)

Screw a snap fuze or a tilt fuze, with detonator, into the booster charge.

(c)

Arm the fuze in accordance with instructions outlined in chapter 5.

Figure 87. Topfmine B.

g. Neutralizing Topfmines A and B.

(1)

Pressure plate up.

(a)

Uncover the mine and make sure that the pressure plate is not depressed and that the mine is undamaged, especially along the shear groove of the pressure plate.

(b)

Check for and neutralize any activating fuzes.

(c)

Lift the mine carefully, rest it on one side, and unscrew the glass fuze-assemb-ly plug.

(d)

Unscrew the Topfmine fuze SF 1 from the wooden fuze-and-booster-charge holder.

(e)

Unscrew the detonator from the fuze.

(2)

Pressure plate down.

(a)

Carefully uncover the mine and fuze.

(b)

Cut any slack trip wires attached to the extension rod or tilt rod of the fuze.

(c)

Neutralize the fuze in accordance with the instructions outlined in chapter 5.

h. Neutralizing Topfmine C.

(1)

With the Topfmine fuze SF 1.

(a)

Uncover the mine and make sure that the glass pressure plug is not de-pressed and that the mine is undamaged.

(b)

Check for and neutralize any activating fuzes.

(c)

Unscrew the glass pressure plug from the mine.

(d)

Unscrew the fuze from the booster charge.

(e)

Unscrew the detonator from the fuze.

(2)

With a snap fuze or a tilt fuze.

(a)

Carefully uncover the mine and fuze.

(b)

Cut any slack trip wires attached to the extension rod or tilt rod of the fuze.

(c)

Check for and neutralize any activated fuzes.

(d)

Neutralize the fuze in accordance with the instructions outlined in chapter 5.

Figure 88. Topfmine C (Pappmine).

f. Packing.

(1)

The mines are individually packed in open wooden crates, marked To.Mi. 4531 or To.Mi. A4531.

(2)

Topfmine fuzes SF 1 are packed separately in wooden cases containing five fuzes. These cases are marked To.Mi.Z. #FGI.

(3)

Nonmetallic detonators are packed separately in small wooden cases containing 15 detonators.

(4)

Armed Topfmines must not be shipped. Neutralized mines may be shipped without being crated, but they must not be stacked.

(5)

Topfmine fuzes SF 1 must be shipped only in their wooden cases.