Tension and Release Firing Device M3

General: This device is specially designed to be used with a trip wire. Unlike the standard pull firing device, the Firing Device M3 must have the trip wire tightly stretched, so as to exert considerable tension on the retaining rod. The device can be activated by tripping, or by cutting the trip wire.

Description: The parts are the body; ratchet reel, retaining rod, striker spring, stri-ker, two safety pins, and standard nipple base. The striker has a split base, froming four jaws which engage the nib on the end of the retaining rod. The ratchet provides a con-venient method for tightening and creating teh desired tension on the trip wire. Safety pin No. 1 cannot be removed until tension has been created on the trip wire to with-drawn the retaining rod sufficiently for the large end of the safety pin to clear the elon-gated safety-pin hole.

Operation: When the device has been properly installed with the explosive charge, the trip wire is attached and tightened by means of the ratchet reel. After the retaining rod has been withdrawn slightly, the safety pin can be removed. The safety pin and safety-pin hole are so designed that it can be removed only after the proper tension has been placed on the trip wire. The positive safety pin is removed last, and the device is the armed.

If a pull of six to ten pounds is exerted on the trip wire, the retaining rod and striker are pulled back and thereby compress the striker spring. As the split end of the striker clears the internal shoulder in the body, the four jaws are forced open and the nib on the retaining rod is pulled free. The jaws then spring together again, and the stiker spring drives the striker down on the percussion cap.

If the trip wire is cut, the striker and retaining rod move inward under influence of the striker spring. As the split end of the striker clears the internal shoulder in the body, the jaws of the striker are spread and pulled free of the nib on the retaining rod by the stri-ker spring, which then forces the striker down on the percussion cap.

Remarks: The device must be securely anchored to enable tension to be placed on the trip wire without dislodging the device or explosive charge.

Figure 252. Tension and Release Device M3