A./P. Mine No. 3 Mk I (Obsolescent)

Diameter

Height

Explosive weight

Explosive

Material

Color

Markings

Fuzing

Pressure required

Description: The Mine No. 3 Mk I has four principal components: the loaded mine body, the pressure plate, the special percussion fuze, and the base propellant charge. The pressure plate is a steel disc, four inches in diameter, threaded to the top of the fuze mechanism.

The mine body consists of a cylindrical, corrugated-steel outer casing containing the explosive main charge, and a central tube, threaded into the base of the mine body for the insertion of the fuze mechanism and the propellant charge. A long tubular recess is provided in one side of the center tube for the insertion of the instantaneous fuse and detonator.

The fuze mechanism consists of a striker holder sleeve, one end of which is threaded into the top of the mine, while the other end is crimped over to retain the operating sleeve. Threaded to the inside of the striker holder sleeve is the tubular striker holder. The striker rides in this holder, and the striker spring abuts against the lower edge of the holder.

In the upper part of the striker holder are three retaining balls, which engage a groove in the striker, and retain it in the cocket position. The balls are kept from moving out-ward by the ball-retaining sleeve. Two annular grooves are cut on the inside of the ball-retaining sleeve. The upper groove is deep and the lower one shallow. In the cocked po-sition, the retaining balls ride in the lower groove, which is shallow enough to force the balls into the striker groove, but sufficiently deep to prevent the ball-retaining sleeve from moving freely inside the striker-holder sleeve. Immediately above, and resting on the retaining sleeve, is the operating sleeve. This sleeve is held upward by the top spring, but is prevented from being forced out of the fuze by the turned edges of the striker-holder sleeve. The top of the operating sleeve is threaded to receive the pressure plate.

A safety spider with four prongs slips over the threaded part of the operating sleeve, and the prongs pass through four holes in the pressure plate and bear against the top of the stricker-holder sleeve. A wing nut holds the safety spider securely in position. When the safety spider is in position, the operating sleeve is prevented from moving, thus mak-ing the mine safe. The safety spider and wing nuts are removed when the mine is armed.

The fuze functions when sufficient pressure is placed on the pressure plate to tilt or force the operating sleeve downward. This, in turn, forces the ball-retaining sleeve down until the retaining balls can move into the deep upper groove. The striker is then releas-ed and initiates the explosive system.

The base assembly consists of a threaded collar into which is fitted the propellant-charge container. This container holds a charge of about 100 grains of G-20 Gunpowder, and is closed at the bottom by a cup, which is crimped into a groove on the outside of the container. Two holes are drilled in the top of the container and lead directly to the gunpowder charge. The first hole contains a short length of safety fuse, which leads to the percussion cap and priming composition. The second hole contains one end of the length of instantaneous fuse to which the detonator is crimped. Between the detonator and the instantaneous fuse are about 2½ grains of sulphurless meal powder, which pro-vides a slight delay.

Functioning: When the striker hits the percussion cap, the safety fuse is ignited and burns from 1 to 2 sec., allowing sufficient time for the enemy to move forward and re-move his foot from the mine. The flash from the safety fuse ignites the propellant charge and projects the mine into the air. Simultaneously, the flash from the gunpowder ignites the instantaneous fuse, which fires the detonator when the mine is about 2 to 4 feet in the air.

Use: This mine is a bounding anti-personnel mine. The effective lethal range is esti-mated at 30 yards radius.

Assembly and Arming: Place the mine in the ground on a drilled block of wood to provide support. Pack earth around the mine, and then remove the wing nut and safety spider, being careful not to exert any pressure on the pressure plate.

Neutralization: Reverse the process outlined for arming the mine.

Remark: This mine was developed and produced by the Royal Engineers in India.