US2733638A - Striker device for mortar - Google Patents

Description

Feb. 7, 1956 H. o. DONNER 2,733,633

STRIKER DEVICE FOR MORTAR Filed June 9. 1953 INVENTOR. Hans 0&0 flan/law HGENF'S'.

United States Patent STRIKER DEVICE FOR MORTAR Hans Otto Donner, Tampere, Finland, assignor to Soltam Ltd., Haifa, Israel Application June 9, 1953, Serial No. 360,560

4 Claims; (Cl. 89-1) The present invention relates to new and useful improvements in a striker device for a mortar.

More specifically, the present invention proposes a striker device especially for fire-arms, such as mortars, where cartridge cases of metal are not used and where the powder gases directly affect the breech end of the barrel as well as the striker mechanism in it.

In the constructions used hitherto, the rear part of the mortar projectile carries a special igniter cartridge with a percussion cap in its centre. When the projectile is inserted, usually by letting it drop, into the barrel the projectile aligns the percussion cap with the striker, the weight of the projectile retaining the percussion cap in the breech end of the barrel. When released, the striker hits on the percussion cap, which ignites the basic charge and this in turn ignites the supplementary charges, so that the pressure of powder gases is free to affect directly the breech end of the barrel and the striker device in it. Thus the powder gases penetrate through the boring in which the striker moves in the longitudinal direction, rearward into the entire striker device. Firstly, the powder gases cause corrosion on the striker and the boring for the striker and, in addition, smirch the more rearward situated striker devices and render all machined surfaces subject to rusting.

The object of this invention is to eliminate entirely the disadvantages stated above, or render them as insignificant as possible. This invention is characterized in that the striker is enclosed in a tube of elastic material, whose surface the pressure of powder gases are allowed to affect so as to compress the elastic tube against the striker and so prevent the powder gases from entering the rear parts of the striker mechanism.

For describing the invention, the following detailed description and the accompanying drawing present a construction consistent with the present invention, without limiting the scope of the invention specifically to the illustrated embodiment.

The accompanying drawing shows in longitudinal section the striker device located in the breech end of the barrel, together with the striker gaskets in conformity with the invention.

The most important details and structural components are as follows:

The breech end 1 of the mortar has a tapped cap 2 attached to its end in such a manner that the striker mechanism proper is inside the breech lid 1 and the cap 2. That end of the firing pin 5 which hits on the percussion cap is indicated by number 3. Near the upper end of the firing pin 5 there are, grooves 4 and below them the straight and smooth main body portion of the firing pin 5. The parts 6 are gaskets of various kind and stops for limiting the travel of the firing pin. The striker spring shown in cross section is indicated by reference number 7. The firing pin 5 is surrounded by a tubelike part 8 made of elastic material. In the construction shown on the drawing the tube-like part 8 has been made ice by placing inside the separate body piece 9 an insert 10 made of bronze and having a circular pressure space 11, so that a relatively thin tube-like part 8 is left between the firing pin 5 and the pressure space 11. Parts 9, 10 are attached, both at the front surface along the circular line 12 and at the rear surface along the circular line 13, to each other; a pressure resistant attachment being eifected by welding. The body piece 9 is provided, in addition, with external threads 14 and borings 15, by means of which the body piece can be screwed into cap 2. m th borings 1 her exten b t ns wh ch municate with the pressurespace 11. The insert 10 is provided with a groove 17 at the level of the bottom of the borings 15, the idea being to render insert 10 elastic while under the pressure of powder gases.

At the moment of discharge the striker device functions as follows:

When released, the striker pin 5 hits on the percussion cap and at the same moment has moved to its front position so that the head 3 of the firing pin projects above the top face of the striker device. The explosion gases generated in the barrel enter, through the borings 15, into the groove 17 and, also through borings 16, into the pressure space 11 with full pressure thereby causing the tube-like part 8 around the firing pin to be pressed tightly against the firing pin. At the same time the pOWder gases, penetrating between the bottom of the basic charge and the top face of the striker device 18, have to some extent entered the striker boring, but the labyrinth grooves 4 on the striker retard the flow of the gases and reduce their pressure to such an extent that when reaching the striker pin the pressure of the powder gases in the space between the firing pin 5 and the component 10 is quite low, and so the tube-like part 8 is capable of being pressed tightly against the striker pin, the gases being thus prevented from entering the rear parts of the striker device and from causing corrosion on the firing pin and on the surrounding insert 10 since there occurs no flow of gases between them. The existence of explosion gases as such does not cause corrosion, it is the flow of explosion gases at high velocities along a metal surface that leads to corrosion.

Since the striker device remains in its front position, the tube-like part 8 is pressed against the practically stationary firing pin 5, and after the projectile has left the barrel the pressureof the explosion gases ceases abruptly and, due to the elasticity of its material, the tube-like part 8 widens outward and releases the firing pin 5. Thus the striker is, immediately after the discharge of the projectile, ready to be reset. Since there occurs no movement while the parts are pressed against each other under pressure, there occurs no wear in a striker device constructed in accordance with the present invention. As no actually moving parts are included in the device, its operation is particularly reliable, its construction simple and its manufacturing costs remain small.

Having thus described my invention, what I claim as new and desire to secure by United States Letters Patent is:

l. A striker device for use in the barrel of a field mortar or similar firearm, comprising a cap adapted to be mounted within the breech end of a barrel and having an axial bore extending therethrough and a recess c0- axial with said bore and opening at the side of said cap facing toward the mouth of the barrel, a spring-urged firing pin slidable in said axial bore, and a member secured in said recess and extending around the related portion of said firing pin, said member having internal spaces separated from the firing pin by resilient walls and opening at said side of the cap facing toward the mouth end of the barrel so that the explosion gases resulting from the discharge of a projectile from the barrel can enter said spaces to urge said resilient walls radially inward against said firing pin for preventing the travel of the explosion gases through the annular clearance between said firing pin and said member and into said bore. g a

2. A striker device according to claim 1; wherein said member includes an inner tube-like part around said firing pin and an outer ring-like part threaded in said recess and joined to said tube-like part, said tube-like part having annular grooves in the outer surface thereof defining said internal spaces and said ring-like part having passages opening at their opposite ends into said annular recesses and at the face of said ring-like part directed toward the month end of the barrel.

3. A striker device according to claim 2; wherein said tube-like part is formed of bronze so that the portions thereof disposed inwardly of said annular recesses define said resilient walls.

4. A striker device according to claim 1; wherein said firing pin has a series of annular grooves therein adjacent the end of the pin extending toward the mouth end of the barrel for decelerating the explosion gases passing around said pin before such gases reach the portion of the pin engaged by said resilient walls.

References Cited in the file of this patent UNITED STATES PATENTS

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