Patent GB-1087797-A (GB)
Title: Water jet propulsion apparatus
IPC: F04D3/00
Filed: 1964-12-30
Abstract: 1,087,797. Marine jet-propulsion apparatus. TAMCO Ltd. Dec. 30, 1964 [Feb. 14, 1964], No. 52887/64. Heading B7V. In marine jet-propulsion apparatus, water drawn by a pair of contra-rotating propellers 32, 33, Fig. 2, through an opening 4 in the bottom 5 of a watercraft is ejected through a nozzle 14 situated astern of the craft's transom 9, the nozzle being rotatably mounted in a socket 111 so as to effect reversal and steering of the craft. The propellers are attached to coaxial shafts 19, 87 that are coupled to an engine (not shown in the drawings) by differential gearing lodged in a housing 18 and a coupling 20. Bearings 81, 88 for the shafts 19, 87 are supported by webs 30, 31 which divide an intake 3 and a discharge elbow 12 into a plurality of channels that suppress turbulence and prevent undesirable collection of solid matter when the craft is in shallow water by minimizing the maximum velocity (P), Figs. 12 to 12b (not shown), of the water passing through the apparatus. The nozzle 14 carries a rudder 120 and is connected to the helm by shafts 141, 148 and gearing (160), Figs. 9 and 10 (not shown). The gearing (160) includes a gear-wheel (164), which is attached to the shaft (148) and a plate (165) carrying an internally-toothed gear-wheel (170), the wheels (164, 170) being coupled to each other by a plurality of pinions (175) rotatably mounted on a further plate (162) that is rotatable about the shaft (148). Arms (171, 172) attached to the plates (162, 165) are moved in either direction to effect reversal and steering of the craft, respectively. In a modification, Fig. 4 (not shown), the nozzle 14 is connected to the helm by a pinion 129 which is fixed to a shaft (128) and meshes with a gear-ring (130) on the nozzle. The output of the nozzle may be regulated by a pair of pivoted plates or deflectors (210), Fig. 4a (not shown), whose positions are set by screws (214). Alternatively, a conical plug (190), Fig. 3 (not shown), is lodged in the mouth of the nozzle 14 and can be retracted by a flexible cable (198) against the action of a compression spring (193). The output of the nozzle may be varied, in accordance with the pressure developed by the propellers, by a stationary plug (225), Fig. 5 (not shown), the nozzle being axially movable away from the plug against the action of a plurality of compression springs (228). In an alternative embodiment of the apparatus, Fig. 7, water is drawn through the opening 4 and a plurality of flexible intake-tubes 35 by a pair of propellers 32, 33, which are fixed to a common driving-shaft 19, the tubes 35 being made of, e.g. polyethylene. Weeds entering the opening 4 are severed by a pair of rotary blades 64 in combination with a stationary plate (68), Fig. 8 (not shown). The blades 64 are attached to a disc 61 that is rotated by a shaft 42 through gearing 44, 53 and a clutch 70. Apertures 62 in a stationary disc 67 adjacent the disc 61 receive the inlet ends of the tubes 35. The shaft 42 is connected to the engine and also rotates the shaft 19. Cavitation effected by the propellers 32, 33 (in both of the embodi ments) is minimized by the trailing portion of each propeller being slightly displaced in a circumferential direction relative to the remainder of the propeller.