Text copied from TM9-1985-2 German Explosive Ordnance 1953 :
Description: This type of igniter is generally used with mines and prepared charges which are actuated by wires in tension. The body of the igniter consists of four parts: the main housing, the guide piece, the spacer piece, ad the lower piece. The main housing contains the sliding cylinder and the compression spring. The lower piece contains the percussion cap. Housed within the sliding cylinder are the striker spring, the striker, and the two opposing pins which hold the striker in place. At the top of the sliding cylinder is a hole, through which a trip wire is securely tied. The collar has two diametrically opposite slotted openings, having a clearance of 1/32 inch for the free movement of the safety pin. The safety pin has a nut on oe end. When in a "safe" position the safety pin is inserted far enough through the hole to permit the shoulder on the safety pin to fit in the recess or groove provided on the upper end of the housing, and the clip is fitted around the collar. When the safety pin, the nut, and the clip are in the position described, the igniter cannot be fired, since any pull of a cord attached to the ring will cause the loose link ring to open and the cord to become detached.
Operation: The trip wire on this uze must be under tension as the fuze is fired by pulling on the trip wire or by loosening, breaking or cutting it. Pulling on the trip wire causes the sliding cylinder to be pulled outward against the resistance of the compression spring. This permits the two locking pins to be forced outward into the upper open space and frees the striker. Cutting or breaking the trip wire permits the compression spring to force the sliding cylinder downwards, permitting the locking pins to be forced outwards into the lower open space and freeing the striker. In both cases, the freed striker is driven into the percussion cap by the compressed striker spring.
Employment: This igniter is used extensively with S mines, prepared charges and booby traps.
Remarks: This igniter proved so dangerous in use that a number were returned to the factory for modification. The modified igniters are stamped "Nur Zügzünder" (only pull fuze). Interior works are the same but the trip wire slot was fired by withdrawal of the safety pin to which the trip wire was attached.