Patent GB-789591-A (GB)
Title: Arrangement for controlling a ship stabiliser
IPC: G01C19/44
Filed: 1953-08-05
Abstract: 789,591. Stabilizing ships. RESEARCH INTERESTS, Ltd. (Oster, L. E. W. Montrose-). Aug. 5, 1954 [Aug. 5, 1953], No. 21606/53. Class 113. [Also in Group XXXV] In ship stabilizing equipment employing a moving weight (solid or liquid) for effecting stabilization and control means for effecting displacement of the weight about a neutral position or state in accordance with the wave action, further means are provided for effecting a displacement of said neutral position or state in one direction or the other to compensate for a static list of the ship with respect to the vertical (true or apparent). Said control means comprises a follow-up system, and said further means includes a switch governing the supply of current to, and direction of operation of, a motor 12 which drives a worm 13 engaging a - toothed wheel 14 fixed to the cage 15 of a conventional differential gear. The switch may be a mercury one or, as in Fig. 2, may comprise contact segments 9, 10 and a contact finger 7 with electrical connection 11 to a terminal 8 and fixed to the ring 3 of a gyroscope which may form part of the normal control mechanism for the stabilizer. An embodiment of the invention having a mechanical follow-up system is described ; that shown in Fig. 3 has an electrical one. The displacement of the moving weight of the stabilizing equipment, such as described in Specification 689,682, is transmitted by a pinion 18 to a pinion 17 and the free shaft 16 of the differential gear, the other free shaft 19 of which terminates in an arm 20 with a wipe contact 21. Coaxial with shaft 19 is a shaft 22 having an arm 23 with a wipe contact 24 and a pinion 25 which meshes with a pinion 26 mounted on a shaft 27 operated by a known regulator device indicated at 28. The device 28 may be as described in Specification 689,681. The contacts 21, 24 are displaced over the contact elements 29 of a potentiometer 31 so that according to the relative position of the arms 20, 23 an electromotive force can exist between the slip rings 32 and 33 with which the arms are in permanent contact. The rings are connected to the device 28 and said force determines the action of the stabilizing equipment in known manner. If the regulator 28 causes pinion 26 to turn anticlockwise, shaft 22 and contact 24 turn clockwise, an electro-motive force is produced between 24 and 21 hence the stabilizer is brought into action and turns pinion 18 clockwise, causing shaft 16 to turn anticlockwise. The cage 15 being stationary, clockwise movement is produced in the shaft 19 and this tends to restore contact 21 to the position of contact 24, the couple produced by the stabilizer ceasing to change as soon as this restoration is complete. Assuming the ship is rolling to starboard, the finger 7 will contact segment 10 causing motor 12 to start, the worm 13 and wheel 14 rotating the cage 15 anti-clockwise, thus increasing the spacing between contacts 21 and 24. The motor continues as long as the ship is inclined to starboard, stops when the gyro passes through the neutral position, and reverses when there is a list to port. In a regular roll, the resultant action of the motor 12 is zero. If, e.g., due to a list, the roll is more pronounced in one direction than in the other, the motor 12 will displace contact 21 more in one direction than it returns it to the other. Consequently there is pronounced displacement of the movable weight in one direction until the ship has been stabilized in the vertical. Specifications 410,820, 517,163 and 517,166 also are referred to.