Switch No. 5 Pressure Mk ISwitch No. 7 Press-Pull Mk I
U.S.N.B.D. - BRITISH LAND MINES AND FIRING DEVICES
FIRING DEVICES

 

 

 

WIDTH

9/16 in.

BRITISH SWITCH

HEIGHT

3/4 in.

NO. 6
RELEASE

LENGTH

4-1/2 in. (with adapter)

WEIGHT

3-1/2 oz.

MATERIAL

Alloy metal

MIN. SAFE LOAD

6 lbs.

Mk I

COLOR

Matt khaki  

 

 

(SERVICE)

 

   

 

   

 

   
     

USE:

This switch is designed for booby trap installations where initiation by release of pressure is desired. Its design allows it to be inserted into narrow openings, as under a door, behind a drawer, etc. It is designed to withstand the weight of heavy objects, such as packing cases, etc.

DESCRIPTION:

This switch consists of a body, over which is fitted a lid, hinged at one end. In the body is located a spring-loaded striker held in position by a safety pin inserted through the sides of the body and through the striker. In addition, when the lid is seated frimly down on the body, a trip lever hinged in the sides of the body engages a notch in the  striker and holds the striker back against its spring. A stop pin limits the movement of the trip lever in an upward direction. The body is threaded internally at the open end to receive a standard fuse adapter.

FUNCTIONING:

When the restraining load on the lid is removed, the pressure of the trip lever forces the lid up. The trip lever is then allowed to swing in a counter-clockwise direction and become disengaged from the notch in the striker. The striker spring then forces the striker into the percussion cap.

INSTALLING & ARMING:

Insert necessary length of safety fuse in fuse adapter. Install the switch in the de-sired position, then connect the other end of the safety fuse to the explosive charge. Withdraw the safety pin, which should come away easily, since the trip lever has forced back the striker and unlocked the safety pin. If the safety pin does not withdraw freely, then the weight on the switch lid is insufficient and should be increased. Do not at-tempt to force out a safety pin which seems to "stick".

DISARMING:

If the device is accessible, insert a safety pin in the safety pin hole, cut the safety fuse connecting the switch to the explosive charge, and remove the fuse adapter. If the switch is inaccessible, cutting the safety fuse will have to suffice.

REMARKS:

1. To reset this switch, unscrew the fuse adapter and withdraw the striker and spring. Throw the trip lever over until it rests on the stop pin. Insert the spring and the striker, the notch on the striker uppermost. Force back the striker with a pencil or rod, and insert the safety pin. Throw the trip lever forward, and close the lid. Screw in a new fuse adapter with percussion cap.

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

Switch No. 5 Pressure Mk ISwitch No. 7 Press-Pull Mk I