Patent GB-108046-A (GB)
IPC: B63H23/24
Abstract: 108,046. British Thomson-Houston Co., (General Electric Co.). Aug. 11, 1916. Systems depending on the use of two or more motors. -Relates to ships having propellers on both sides driven by alternating current electromotors receiving current from a turbogenerator, and consists in providing means whereby the steering of the ship is presented from imposing detrimental excess torque upon any of the propellerdriving motors Means are provided for preventing an increased admission of motive fluid to the turbine to meet the increased load on either of the propellerdriving electromotors when the ship is moving in the arc of a circle. Such means may consist in a device for automatically adjusting the governing- mechanism of the turbine for a lower speed limit when the direction of the ship's course is altered, the adjustment being made in response to movements of the rudder or to changes in load of the propellerdriving motors. In one construction, Fig. 1, having adjustable speed-governing mechanism of the kind de. scribed in Specification 3026/13, [Class 57, Governors &c.], the supply of motive fluid to the turbine driving the generator is controlled by a series of valves which are operated by a series of cams 10 on a shaft 11. The shaft 11 is adapted to be rotated by a pinion 13 and a rack 12 operated by a hydraulic motor 22 under the control of a pilot valve 21 which is operatively connected through a floating lever 20 with a speedgovernor 15 driven by the turbine shaft. The fulcrum F is adjustable by a rod 24 as described in the above mentioned Specification, and, according to the present invention, each movement of the rod 24 causes a corresponding movement of a lever 25 having a projection 27, which projecjection takes up a position limiting the movement of the lever 20 in response to the governor 15 when the load on the turbine increases. Since this device prevents any increase in aggregate load, it reduces the excess load that would be thrown on the most heavily loaded propeller and diminishes the tendency of the propeller-driving motor to break down. A control device responsive to a difference in the loads of the two propeller-driving motors 30, 31 is shown in Figs. 2 and 3, wherein the electro-motors 30, 31 receive energy from a two-phase alternating current generator 34 driven by a turbine 35 having inlet valves operated by a cam shaft 11 connected to the turbine governor 15 and the operating rod 24 as described with reference to Fig. 1. Current transformers 40, 41 are connected in the leads of one phase of the motors 30, 31, while current transformers 42, 43 are connected in the other phase. A two-phase electric motor 45 has its two phases connected across the series-connected secondary windings of transformers 40-41, 42-43, so that a current flows in the circuits of the motor 45 proportional to the difference in the currents supplied to the main motors 30, 31. The shaft of the motor 45 carries a pinion 46 meshing with a gear 47 slidably mounted on a turnbuckle 48, which engages the screwed ends of the two parts of the operating rod 24. Thus, any torque of the motor 45 due to the motors 30, 31 becoming unequally loaded effects an adjustment of the fulcrum F for a lower speed limit of the turbine. When the loads on the motors 30, 31 again become equal, a spring 49 restores the turnbuchle 48 to its initial position. In another modification, Fig. 4, the movement of the rudder 70 is caused to move the operating rod 24 through the medium of a cam 72 and arm 74<1> so as to decrease the speed which the governing-mechanism is adjusted to maintain.