British Switches

Pressure switch.

The pressure switch consists of the following parts:-

(1) Main casing and base plate.

(2) Striker rod, block and spring.

(4) Adapter and collar.

The main casing is made of brass. In the base there are small holes for attachment to any suitable surface. The striker and rod are made of cast iron 1/8" in diameter, reduced to 1/16" under the shear stud, which will break it under a point load of 30-40 lbs.

A heavier striker is also available, which is 3/16" in diameter, reduced to 3/32" under the shear stud and will fire under a load of 60-80 lbs.

The metal shear stud is provided with a V shaped cutting edge and shoulders to keep it in position on the striker rod.

The adapter and collar are fitted with a service cap, and designed to take either safety or instantaneous fuse.

When a load of 30-40 lbs. is applied to the top of the shear stud, the striker rod will be sheared, allowing the striker to be driven forward by the spring and firing the cap and charge.

Pull switch,

This consists of a barrel in which moves a striker block, with a tubular tail split into four quadrants. On the end of each is a small lip. In the set position, these quadrants are splayed outwards by the point of the firing pin which is pressed forward by the retaining spring in the top collar.

The striker is then held up against the firing spring, by the lips on the tail engaging with a platform in the head of the barrel. Screwed on the bottom of the barrel by means of another collar is an adapter with a cap, also for the firing of the igniter safety fuse.

When the firing pin is pulled outwards, with a force of 1 lb., the split tail contracts to normal, enabling the lips to pass through the platform in the head and the striker to be driven down on the cap by the firing spring.

Time pencil fuse.

The time pencil fuse consists essentially of the following parts:-

(1) A thin copper sleeve containing a phial of corrosive liquid.

(2) A thin aluminum sleeve.

(3) A striker with spring and retaining wire.

(4) Fuse adapter and firing cap.

The striker is held back against the spring by a thin, steel wire anchored to the top of the copper sleeve. When this copper sleeve is crimped and the phial is broken, its contents of corrosive liquid attacks the striker retaining wire. When this steel wire is eaten through, the striker fires the cap in the base and, in turn, the charge.

It is important to note, that the copper sleeve must be crimped flat and not bent round and the safety-pin withdrawn. Two fuses should be used for each important charge to guard against risk of failure.

Solid Bhrapnel charges.

The following prepared charges consists of high explosive wrapped in varnished paper and contains a screwed metal bush for inserting a prepared detona tor or igniter Pull or Push, etc.

Small bore-hole charge,(cylindrical) 100 grams = 3,5 oz. which can be either Tolite or Picric acid.

Rectangular Charge 200 grams = 7 oz. threaded bush, for prepared detonator or This resembles a cake of soap, screw- igniter (Pull or Push, etc.) ed metal bush on one side with standard The following prepared charges con-

sist of solid high explosive in a metal rase.

{a) Medium HE charge. 1 Kilo = 2 lbs. Metal container, consisting of rectangular metal case containing TNT or Picric acid explosive, 3 standard threaded metal bushes on different sides to fluctuate their groupings to form demolition charge of any weight.

(b) Heavy HE charge 3 K"i3o = 6.5 lbs. Contained in metal case as 1 kilo block.

3 standard threaded metal bushes on different sides. Has carrying handle fitted to top, mainly for bridge demolition.

Contentsi Picric acid or Tolite.

The explosives are either as above, labels cover each of the bush holes and are either yellow or orange. Yellow indicates Picric acid and orange indicates Tolite. The labels are naturally pierced when inserting the detonators.

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