Patent GB-218997-A (GB)
Title: Improved arrangement for rotatable planes working in a current, such as rudders, blades of variable pitch, screw propellors, pumps, turbines, sails for ships and like rotatable planes
IPC: B63H25/38
Filed: 1924-07-01
Abstract: 218,997. Naamlooze Vennootschap Instituut voor Aero-en Hydro-Dynamiek. July 14, 1923, [Convention date]. Rudders; steering-gear; screw and like propellers.-Gear in which a freely mounted rotatable surface, such as a rudder or sail, is operated indirectly through more than one effective range, e.g. ahead and astern, by the stream-pressure on a small auxiliary surface, is characterized by the feature that, whilst the auxiliary surface is passing from one effective range of the surface to another effective range, the gear between the operating-gear of the direction indicator and the auxiliary surface is controlled by a separate intermediate-gear which, on the direction indicator being moved in one sense, causes relative movement in the same sense of the auxiliary surface to the main surface in both effective positions independently of the means for operating the auxiliary surface. In the form shown in Fig. 2, the auxiliary rudder 12 mounted on the main rudder 11 is operated from the double-cam disc direction indicator 13 which is actuated from the steering-wheel by means of the worm 14 and the worm-wheel 15, through the double cam lever 16, the oscillations of which are transmitted through the cranks 17, 19, the connecting-rods 18, 20, and the chain drive 21, 22, 23 to the shaft 24 of the auxiliary rudder. This gear is controlled by an intermediate-gear, the motion of which is prescribed, for example, by an eccentric disc 26, which may be either fixed or adjustable with reference to the ship, but is designed to exert a maximum throw to one side or the other on the eccentric lever 31 when the main rudder is in the range of the effective position for moving ahead or astern. The eccentric lever is connected up to the auxiliary rudder gear through the cranks 32, 33 and the link 34. In a modification, the auxiliary rudder is controlled by the intermediate gear only during the passage of the auxiliary surface from the range of one effective position into that of the other, the direction-indicator being released. This end is achieved by causing an inclined-surface mechanism to engage or disengage a, guide-roller on the direction indicator mechanism from an appropriately-shaped cam groove forming part of the intermediate gear. In another form in which a differential gear is employed, the ring of teeth 71. Fig. 7, is rigidly connected in the worm wheel 15 by which the direction indicator is operated while the other member 72 of the differential gear is rigidly connected to the direction indicator 13. When the surfaces are in the operative position, the wheels 74, 75, constituting the intermediate member of the differential gear, are locked by a Maltese cross 77 which is prevented from moving, when the rudder is within the range of either effective position, by the ribs 78, 79 formed on the casing 30, which is fixed relatively to the ship. On the circular ribs 78, 79 releasing the cross, when the rudder is in intermediate positions, the cross is turned by pins 85, 86, and thereby the gear 80, 81 and the differential gear 73 - - 75 which effects the turning of the direction indicator into the position. of the new effective range.