GB348832A - Improvements relating to speed indicators for ships - Google Patents

Abstract

348,832. Ships' logs. WALKER & SON, Ltd., T., WALKER, T. S., and WALKER, J., 58, Oxford Street, Birming- ham. April 11, 1930, No. 11553. [Class 97 (ii).] In an electric speed indicator for ships a uniformly moving time element is coupled to an indicating member for a period controlled by an element which moves in proportion to the distance traversed and is electrically operated by a ship's log. In the form shown, the electromagnet 1, Fig. 4, and leads 2 are intermittently energized by contact mechanism operated by the ship's log (not shown). A spring- urged pawl 6 mounted on the armature 3 engages and drives a ratchet wheel 9 on the shaft 10 the angle of rotation of which is thus proportional to the distance traversed. A contact 17 in series with the leads 18, 19 is intermittently closed by the engagement of a roller 16 on the blade-spring 15 with a cam 11 on the shaft 10. In the indicating member, Fig. 1, is mounted a uniformly rotating time shaft 23 on which a spider frame carrying a number of electromagnets 36 is mounted. A dial drum 22 graduated to indicate speeds, and soft iron flanged disc 33 are rotatably mounted on a fixed sleeve 26 and are attached thereto by spiral springs 34, 35, respectively, which bias them towards a zero position. The leads 18, 19 from the distance element, Fig. 4, are connected through a battery and rotary terminals 38, 39 to the electromagnets 36 which when energized attract the disc 33 and carry it round with the time shaft 23. A peg on the disc 33 is adapted to engage a peg 43 on the dial 22, the latter being carried round with the disc 33 and time shaft 23 to give an indication of the time taken by the ship to traverse a standard distance. When the circuit including the leads 18, 19 is broken the disc 33 is returned to the zero position by the spring 35 but the dial 22 is retained in the indicating position by the spring-urged brake 48 which however is adapted to be withdrawn by the electromagnet 49 when the contact 17 closes to start another indicating cycle. In order to provide a measurement of speed throughout a wide range a battery of electromagnets, discs, dials and cams may be provided, the electromagnets being geared to the time shaft to rotate at different uniform speeds and the cams being varied to correspond to different standard distances. To obtain a continuous indication a single dial may be actuated alternately by two sets of mechanism controlled by independent cams operated by a single log.