Patent GB-430516-A (GB)
Title: Improvements in apparatus for determining positions of vessels on the earth
IPC: G01C21/20
Filed: 1934-01-27
Abstract: 430,516. Course-recording apparatus. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(Pitometer Log Corporation ; 206, Lafayette Street, New York, U.S.A.) Jan. 27, 1934, No. 2886. [Class 97 (ii)] A latitude indicator and a longitude indicator are controlled by an element operated from a ship's log and compass. The control element is mounted for rotation about two different axes and is oriented about the first axis in accordance with the direction of travel of the supporting vessel and rocked about the second axis at a frequency dependent upon the speed of the vessel. Rocking about the second axis may be arranged to move two friction wheels adapted to be rotated by amounts proportional to the distance travelled in the N-S and E-W directions respectively and geared to the indicators. In the form shown, a shaft 51, geared to a motor controlled by the ship's compass, carries by a Hooke's joint 48, 49, 50, a frame 26 which supports a ring member 41 by pivots 42. The member 41 has an inwardly extending tongue 42<1> adapted to engage a cup member 27 fastened on a shaft 24 which is slidably mounted in a bearing 25 in the frame 26. A motor 15, controlled by the ship's log so as to make one revolution every time the ship travels a predetermined distance, drives a shaft 16 carrying a cam 20 adapted through a spring plunger 31 engaging a collar 29 rotatably mounted on the shaft 24 to rock the frame 26 about the joint 48-50 and bring the ring 41 into contact with friction wheels 64, 111. Thereupon a further cam 19 on the shaft 16 rocks a lever 21 engaging a fixed collar 23 on the shaft 24 and causes the member 27 and shaft 24 to be depressed against a spring 28. The consequent rocking of the ring 41 about the pivots 42 causes the wheels 64, 111 to be driven in proportions dependent upon the orientation of the frame 26 which in turn is dependent upon the ship's course. The rocking of the ring 41 is limited by adjustable stops 59, 61. A return spring 44 is provided for the ring 41 and a return spring, (not shown), withdraws the frame 26 and shaft 24 when permitted by the cam 20. The friction wheel 64 is keyed to a shaft 66 geared to a shaft 82, (not shown), by a sprocket 71 or pinion 74, either of which may be brought into operation by a clutch 76 controlled from outside the casing 10 according to whether the ship is in the Northern or Southern hemispheres. The shaft 82 is geared to a latitude indicator 90. The spindle 112 of the friction wheel 111 is rotatably mounted in a frame 110 and carries a gear 118 meshing with a gear 116, Fig. 3, geared in turn to the longitude indicator 125. The change of longitude with distance travelled in an E-W direction varies as the reciprocal of the cosine of the latitude. In order to effect this adjustment the wheel 111 is made hemispherical and is rotated together with the frame 110 and a toothed sector 108 fixed thereto about an axis 109 by gearing 107, 99, 94 from the shaft 82, (not shown), in accordance with the latitude changes. A key is provided for manually setting the latitude and longitude indicators.