Patent GB-251269-A (GB)
Title: Improvements in or relating to sound receiving devices for submarine signalling
IPC: G01S1/72
Filed: 1926-04-19
Abstract: 251,269. Walker Signal & Equipment Corporation, (Assignees of Walker, W. L.). April 25, 1925, [Convention date]. Detecting subaqueous sounds.- Submarine signalling apparatus comprises an enclosed self-contained diaphragm-microphone unit removably fastened to a seating in or on an outer casing which extends through an aperture in the ship's hull, said casing being susceptible of watertight closure between the aperture and the unit for the purpose of removing the latter from its seating without ingress of water to the ship. The casing 1, Fig. 2 of the sound receiver is provided with a cover 2 hinged at the point 3 and held in place against packing 4 by hinged bolts 6 and nuts 7, Fig. 4, engaging lugs 2<1> in the cover 2. The diaphragm 14 which is of hard rubber or other non-corrodible, material is flush with the surface of the hull of the ship and is held in place on the casing 9 by a screwed ring 17 and gaskets. The casing 9 has a cover 19 held in place by a screwed ring 21 moved home by a suitable wrench engaging lugs 22. The lead-in wires pass through a gland 24 in the cover 19 and also through a second gland 25 in the cover 2. Two microphones 36, 37, Fig. 6, are carried at the ends of an arm 35 on a lever 32 fulcrummed on two stretched metal filaments 29, 30 on a base 26. The lever 32 is fitted with an adjustable counterbalance weight 34 working on a screwed arm attached to the. lever which is also connected to the diaphragm by a rod 38. The cover 19 of the microphone chamber is provided with a screw-threaded plug 45 which allows inspection of the chamber to see whether water has leaked in. When the chamber 9 is first inserted the gasket 15 is covered with a layer of commercial latex and some vulcanizable agent so as to solidify into a water-tight joint. The outer surface of the casing 9 is covered with a heavy grease preferably containing graphite. To remove and replace the casing 9, the cover 2 is swung back, the plug 11 is removed and a hollow plug 46 containing a spring pin substituted. The parts are then as shown in Fig. 7. The cylindrical casing 52 is now'clamped against the packing 4, using the bolts 6. This casing contains a gate valve 53 operated from the hand lever 56. The casing 52 is provided with a removable housing 59 through the end of which passes a screw-threaded hollow spindle 60 the inner end of which is provided with a head 61 carrying segmental pieces 62 which are adapted to enter between corresponding segments 63 on the stuffing box of the gland 24. The spindle 60 encloses a second tube 64 carrying a pair of projections 65 at the inner end and a hand wheel 66 at the outer end. A yoke 71 houses a sleeve 72 having a handle 74 fixed to its end the sleeve being feathered on the spindle 60. The screw-threaded hub of a ratchet wheel 82 is located between a flange 73 on the sleeve 72 and the end of the casing 59. By means of a pivoted pawl on the lever 83 the ratchet wheel may be operated and the spindle 66 advanced or retracted. To remove the casing 9, the end of the cable is passed through the tube 46 and the head 59 secured to the valve casing. The spindle 60 is then advanced to the left until the head 61 and segments 62 are in position to pass between the segments 63. The handle 74 is rotated ninety degrees until the pin 78 enters the hole 79 in the yoke 71. The projections 65 are then pushed into place between the segments 63 by means of the wheel 66. The retaining screws for the casing 9 are then withdrawn and the casing drawn to the right by rotating the ratchet wheel until the position shown in dotted lines is reached. The valve 53 is then closed. The water in the right hand of the valve casing may be released through the cock 86. In replacing the casing 9 the casing is moved until the spring pin 49 snaps into the groove 51, the casing being thea correctly positioned for the replacement of the securing bolts. In modified constructions the valve is permanently connected with the outer casing and the withdrawing mechanism is correspondingly modified. The microphones may be suspended in a yoke by means of stiff springs which yield only to excessive shocks. The chamber 9 may be filled with gaseous fluid under a pressure counterbalancing the pressure produced by the water on the outer side of the diaphragm. The dimensions of the chamber may be so proportioned that the chamber is resonant to the principal signals received.