Patent GB-519936-A (GB)
Title: Improvements in or relating to submarine mines
IPC: F42B22/12
Filed: 1938-09-12
Abstract: 519,936. Submarine mines. TENNANT, W. J., (Aktiebolaget Motala Verkstad). Sept. 12, 1938. No. 26613. [Class 9 (ii)] Moored mines are maintained at a constant depth below the surface by winding and unwinding the mooring line on to a drum which is driven by a propeller impelled by the tidal current, the action of the propeller being controlled by a hydrostatic device and hydraulic servo-system, so as to obtain greater sensitivity. In the form shown, the driving mechanism between the propeller 32, Fig. 1, and the drum 22 for the mooring cable 23 is mounted in a fin 8, which is rotatably mounted about an axis 4 on the mine 2. The drive comprises a propeller shaft 34, and further shafts 36, 52, 56, 58, 62, geared together through worm and bevel gears as shown in Figs. 1 and 4, the latter figure being a sectional plan on the line IV-IV, Fig. 1. The shaft 62 carries a worm 64 which meshes with a worm wheel 66 fixed to a flange 68 on the mine. The shafts 34, 36, are coaxial and are fitted, respectively, with the parts 70, 72, of a claw coupling, the part 70 being fixed to the shaft 34 while the part 72 is displaceable on the shaft 36. A claw coupling 84, 82 is similarly arranged on the coaxial shafts 56, 58, the part 84 of this coupling being displaceable on the shaft 56 by means of a piston rod 86 extending through the hollow shaft 58. The movements of the displaceable parts of the couplings are effected by pistons working in hydraulic cylinders which are supplied with fluid under the control of a hydrostatic depth-regulating device 96. As shown enlarged in Fig. 6, the hydrostatic device comprises a spring-controlled diaphragm 98 which is subjected to the pressure of the sea water and is connected by levers 110, 112 to two slide-valves 114, 116, working, respectively, in valve - chambers. 119, 123. Water under pressure is supplied to the valve chambers from a receptacle 94, and is adapted to be supplied through connections 118, 120, 121, 122, according to the positions of the slide-valves. These connections are connected by pipes to the hydraulic cylinders which control the claw couplings. When the mine is at its correct depth, the connections 118 and 121 convey fluid to the cylinders and in this position the coupling 82, 84 is engaged and the coupling 70, 72, disengaged. The mine cannot rise since the worm and worm gearing 40 between the shafts 36, 52 is self locking. When the water level sinks, the valve 116 is actuated and fluid is supplied through the connection 122 to the cylinder which operates the coupling 70, 72, thus engaging the parts of the coupling and enabling the propeller to drive the winding drum. When the water level rises, the other valve is actuated to disengage the coupling 82, 84, and the mine rises under its own buoyancy. Fluid under pressure is supplied to the receptacle 94 by a pump driven by an eccentric 128 on the shaft 34. By means of a second hydrostatic device connected by a lever 142 to a spring-controlled clutch 132 on the shaft 34, the pump is automatically stopped when the pressure in the receptacle reaches a pre-determined pressure.