Patent GB-264290-A (GB)
Title: Improvements in or relating to submarine mines
IPC: F42B22/18
Filed: 1925-11-27
Abstract: 264,290. Vickers, Ltd., and Pratt, H. B. Nov. 27, 1925. Mines, marine.-Relates to automatically moored mines of the kind in which the mine proper and the anchor are launched as a single unit and become separated from each other by a hydrostatic releasing device when the said unit reaches a depth below the mooring depth desired but above a safe depth below which the flotation chamber would be subjected to excessive pressure, the anchor after this release going to the bottom while the mine remains below the mooring depth, whereupon the mine rises to the mooring depth and is stopped there by a hydrostatic device. According to the invention, (1) a brake for checking the speed of the paying out of the mooring cable after the mine is released from the anchor is so set that during the descent of the anchor to the sea bed the mine will not rise above the mooring depth nor fall below the safe depth, and (2) the depth setting hydrostat is detachably carried by the mine and is released therefrom after stopping the paying out of the mooring cable when the mine finally reaches the mooring depth. As shown in Fig. 2, the mine A is seated over the anchor B and is held in place by a turnbuckle A<1> in conjunction with a hydrostatic device G. The anchor B constitutes an air chamber which gives neutral buoyancy to the combined mine and anchor. In the side wall of the anchor, there is a double-faced valve f, f<1>, Fig. 4, which is kept closed by a spring f<3> compressed by a plunger F<3> and a lever F<2> so long as this lever is confined by the walls of a launching tube. When the mine is launched, the lever is released, and a spring F<1> opens the valve f, f<1>. The two faces of the valve are made of substantially equal areas, and water is admitted to the face f<1> by a hole f<4> to balance the hydrostatic pressure on the face f. As the anchor gets flooded, it sinks with the mine, until the hydrostatic device G releases the mine from the anchor. This device has two diaphragms G<1>, G<2>, Fig. 5, to which water is admitted by holes g<1>, g<2>. Tha diaphragm G<1> is larger than the other and the excess of hydrostatic pressure thereon, when the releasing depth is reached, overcomes a spring G<3> and draws down a sleeve g, bringing an annular groove g<3> therein opposite balls g<4>, which escape and liberate the eye attached to the turnbuckle A<1>. The mine, thus released, moves up and down between the mooring depth and the safe depth while the anchor sinks to the bottom, the speed of the mooring cable drum C<1> being checked by a paddle brake geared to it. After the anchor touches bottom, the mine rises to the mooring depth, when a hydrostatic device D attached to the mine stops the paying out of an auxiliary line E connected by a wire C<3> to a pawl C<2>. The pull of this line then shears a pin c<2>, whereupon the pawl is moved into engagement with a ratchet wheel on the mooring cable drum and is held thus by a spring c<3>. Further pull on the line E shears an attachment pin d<2> of the hydrostatic device D, which then falls away from the mine. Specifications 211,196, 213,313, 262,917, and 264,973, are referred to.