Release Switch No. 3 Mk I (Service)

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Description: The body of the switch consists of a shallow channel section with open ends, and a hinged cover provided with an inclined tongue. Into one side of the body is clipped the fuse adapter, complete with percussion cap, by means of a metal leaf. A two-leaf steel spring is attached at one end to the same upright side as the fuse adap-ter. A striker is fixed to the other end of the spring. A brass block, with a hole borred in its center, is fixed to the bottom of the switch body. A safety-pin hole is drilled in the side of the switch body opposite that to which the striker spring and fuse adapter are attached. A safety pin passes through the switch body, striker head, and brass block.

Functioning: When pressure is removed from the hinged lid of the switch, the press-ure of the spring on the inclined tongue forces the lid upwards. The spring and the striker are then relcased, and the striker is driven into the percussion cap.

Use: This switch may be placed under crates, packages, books, or other suitable ob-jects in booby-trap installations, where initiation by release of pressure is desired. Though rarely used as such, this switch may be employed to initiate demolition charges.

Installing: Bend the leaf spring back until the hole in the striker comes opposite the safety-pin hole in the switch body. Insert the safety pin through the switch body, stri-ker, and brass block. Insert the fuse adapter in the hole in the side of the switch body. Close the lid. Place the switch under a concealing object so that the lid is held tightly closed. Connect the fuse adapter to the explosive charge with safety fuse. Withdraw the safety pin. If sufficient weight has been placed on the lid of the switch, the safety pin will come away easily. On no account should the pin be withdrawn from the switch when the charge is connected, if the pin is at all tight.

Disarming: If the device is accessible, insert a safety pin in the safety-pin hole, cut the safety fuse, and remove the device and the charge. If the device is inaccessible, cutting the safety fuse between the switch and the charge will have to suffice.

Remarks: Test the device for re-use by cocking the switch and slowly releasing pressure on the lid. After testing, recock. The striker may require readjustment following test firing.