GB499644A - Improvements relating to automatic steering systems for ships - Google Patents

Abstract

499,644. Automatic control systems. SPERRY GYROSCOPE CO., Ltd., SAUL, G. C., HARDING, W. G., and NISBET, R. H. June 22,1937, No. 17384. [Class 38 (iv)] Steering.- A manually controlled electric steering system may be controlled by an automatic pilot located, together with change-over switching means, entirely in the neighbourhood of the steering wheel. The rudder motor 3, Fig. 1, is energized by a Ward Leonard generator 4 excited by the unbalance produced by steering upon a Wheatstone bridge comprising a sending or steering wheel potentiometer 12 and a rudder controlled potentiometer 13, and an auxiliary sending potentiometer 12 operated by a standard form of automatic pilot (including for example a compass repeating motor 15) may be substituted by operating a change-over switch 115. The auxiliary potentiometer may be replaced by a dummy potentiometer consisting of contacts connected in sequence to tapping points on the steering wheel potentiometer through a multiple contact switch and multicore cable permitting isolation. The slider or contact arm 101 of the auxiliary or of the dummy potentiometer may be operated by servomotor, such as 27, and the system may include means, such as 118, for manual control during automatic steering ; limit switches 30, 31 are jointly adjustable to determine the limiting rate of turning. The repeat back to the compass actuated controller of the automatic pilot is not from the rudder itself but from the slider of the auxiliary potentiometer and in order to damp the oscillation of the ship a lost motion connection 34 is introduced in this mechanism which effects a reduction of rudder angle during return of the ship to her course; a change speed gear box 36 permits adjustment of rudder ratio. The auxiliary controller may comprise a set of studs in a circular arc and two trolly contacts directly actuated by a compass repeater motor ; two trollys are electrically connected together and arranged so that the circuit is always maintained. Friction is thus reduced and the servomotor 27 may be omitted. In a further modification the repeater motor may turn a shaft with cams each operating in correct sequence finger contacts connecting with the studs of the sending potentiometer ; in one form each cam has a projection to effect a brief circuit closure and in another the cams are eccentrics and each operates upon two switches in series connection and so placed as to effect a brief closure of the circuit. In a further modification the connections may be made by electric relays operated by a controller turned by the repeater motor. The Specification describes also the initial rudder ' arrangements forming the subject-matter of Specification 501,512.