Patent GB-558619-A (GB)
Title: Improvements in or relating to instruments or devices for use in navigation
Filed: 1942-06-03
Abstract: 558,619. Registering apparatus. BELL PUNCH CO., Ltd., and WEBB, C. F. June 3, 1942, No. 7576. [Class 106 (i)] A navigation or position-indicating instrument comprises an element operated according to distance travelled or speed, an element settable according to the direction of travel, and a plurality of devices to register positive and negative components of movement to one side of a zero point or datum line, masking means being provided so as to display only the reading or readings which indicate positively the geographical position reached. In the arrangement shown in Fig. 1 the shaft 1, which is driven at a speed, dependent upon that of the ship, aircraft or other vehicle, is coupled by bevel gears to a friction disc 3 which with a ball 4 and roller 5 forms a variable speed transmission mechanism to a shaft 7 driving a pair of counting mechanisms A, B. A second variable speed mechanism constituted by a friction disc 40, ball 42 and roller 41 is employed to drive a second pair of counting mechanisms C, D. The position of the balls 4, 42, is controlled by means responsive to the direction of movement of the ship, &c. comprising slider elements 10, 43 co-operating with pins 12, 45 on pinions 13, 14 rotated by a pinion 15 operatively connected to a repeater compass or other device. The counters A, B register positive and negative movements to the North and South of a selected zero while the counters C, D register positive and negative movements to the East and West. Each pair of counters is maintained in step or move synchronously as described in Specification 558,644. A convenient form of counting mechanism for reading degrees and minutes is shown in Figs. 3 and 4 ; the sets of numeral wheels 20 ... 23 are rotatably mounted on spindles 54, 55, 56 and 57 arranged in spaced frame plates 50, 51. The shaft 7 is connected by pinions 70, 71 with the gear wheels 20a of the units denomination of the counters B and A. The pinion 71 is rotatably mounted on a shaft 73 which may also carry the transfer pinion 74, 75 and 76 for the carry over movements in the counter A. A similar arrangement is provided for the counter C while the transfer pinions for counters B and D are mounted on shaft 78. A pinion 80 similar to the transfer pinions is mounted on the shafts 73, 78 and is associated with the numeral wheel of highest denomination to co-operate with a gear segment 81 secured to one of the side plates of a bridge piece 84 constituting a shutter movable into and out of position about the shaft of the numeral wheels to mask or uncover the reading apertures. The arrangement is such that in normal position all zero readings are revealed and on the first movement only those counters with positive amounts will be viewable. A variable speed mechanism may be incorporated in the drive to the shafts 7 to correct for drift. Where the counters are graduated to read distance a correction for latitude must be made in the East and West counters. In a modification shown in Fig. 9 the pairs of counters are replaced by a single counter in which the numeral wheels 20b ...23b have two sets of numerals arranged in opposite directions one or other being exposed to view by a shutter device 84b operated in a similar manner to that described above.