GB1372655A - Hydraulic jet propelled water craft driving means - Google Patents

Abstract

1372655 Water jet propulsion TWIN DISC Inc 18 April 1973 [2 May 1972] 18623/73 Heading B7V A water-jet-propelled vessel having a prime mover driving a water pump, a variable area jet nozzle and a reversing device movable into and out of the jet discharge is provided with a forward/neutral/reverse control lever which has connections with (a) the prime mover to vary its speed; (b) means for varying the area of the jet nozzle and (c) means for moving the reversing device. General arrangement (Figs. 1, 4).-An engine E drives a drive shaft 10 via a transmission T. Two impellers 8, 9 which are mounted on the shaft 10 within a pump housing 7 draw water from an opening 1 in the vessel's bottom 2 and eject it partly through a variable area nozzle N, which is rotatable by a ram 45 inside a housing 34, and partly through sidewardly directed steering valves V1, V2. The reversing device comprises a pair of U- section gates 60, 61 which are slidable laterally towards or away from each other by rams 66, 67. When closed together the gates form a duct which deflects the jet backwardly under the vessel to cause it to reverse. Control arrangement (Fig. 2).-A hand lever 75 is movable into a forward position F, a reverse position R and a neutral position (solid lines). A sprocket 79 attached to the lever 75 drives a smote reprocket 80 via a chain and cable device 76. Sprocket 80 is mounted on a shaft 81 whose rotation causes movement of three arms 82, 83, 84. Arm 82 is connected to throttle linkage 85 of the engine, arm 83 is connected via a cam adjustment 87 to a valve 105 which controls the ram 45 for moving the jet nozzle N and arm 84 is connected to a valve 90 which controls the reversing gate operating rams 60, 61. The arrangement is such that a small movement of lever 75 places the craft in either forward or reverse mode by operating the reversing gates 60, 61 (if necessary). Further movement of the lever then increases the engine speed to build up water pressure (e.g. for effective manoevering using steering valves V1, V2) and still further movement begins to open the variable area nozzle N. This opening continues in conjunction with steadily increasing engine speed.