Pressure Switch No. 5 Mk I (Service)

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Description: This mechanism consists of a body enclosed in a case and covered by a hinged lid. Two small holes in the bottom of the case facilitate attachment. Inside the case is located a double trip lever, which engages a notch on the underside of the striker and retains the striker in the cocked position against the compression of the striker spring. The open end of the switch body is threaded internally to receive the fuse adap-ter, which contains the percussion cap. The trip lever is held in the raised position, en-gaging the striker, by a double resistance spring. A safety pin fits through opposite holes in the body, under the trip lever, and through the striker. A brass cylinder screws into a hole in the lid and contains a threaded extension rod.

Functioning: Pressure on the lid or on the extension rod depressed the trip lever against the pressure of the resistance spring and disengages the trip lever from the stri-ker. The striker spring then forces the striker into the percussion cap.

Use: This switch is designed to be used in booby-trap installations where initiation by pressure is desired. An adjustable extension rod facilitates placement under such objects as railroad tracks, duckboards, etc.

Installing: To install the device without the extension rod, place the device in the desired position, and connect fuse adapter to explosive charge with safety fuse. With-draw the safety pin.

To install the device with the extension rod, screw the brass cylinder tightly into the lid, and screw the extension rod to its lowest limit in the cylinder. Set the device in posi-tion, and unscrew the extension rod until contact is made with the object under which it is laid. Connect the fuse adapter to the explosive charge with safety fuse, and withdraw the safety pin. Easy withdrawal of the safety pin is prevented if excessive pressure is applied when setting up on the extension rod. If the safety pin cannot be withdrawn easily, release tension on the extension rod.

Disarming: Insert a safety pin in the safety-pin hole and cut the safety fuse con-necting the switch with the charge. Remove the fuse adapter, and then remove the switch and charge.

Remarks: To recock this switch, unscrew the fuse adapter and withdraw the striker. Reinsert the striker and striker spring, with the striker notch facing downward. Push back the striker with a wooden rod until the lips of the trip lever engage the notch. Insert the safety pin.

This switch is used only for special operations and for preparatory training in these operations.