Patent GB-191203878-A (GB)
Title: Improvements in Apparatus for Indicating the Direction of Rotation of Shafts and the like.
Inventor: KEPPIE PETER RONALD
IPC: G01P13/04
Filed: 1912-02-16
Granted: 1913-02-17
Abstract: 3878. Keppie, P. R., and Maddick, H. M. R. Feb. 16. [Cognate Application, 7951/12.] Revolution - direction indicators in which a moving pointer travels clockwise or anti-clockwise in accordance with the rotations of a shaft and is actuated from the shaft by electric means controlled by switch mechanism on the shaft. In the form shown in Fig. 1, two rings 2 connected to the shaft 1 in opposite senses by freewheel mechanism have contact strips engaged by brushes 4 in circuit with a battery 7 and two electro - magnets 11, 11<a>. According to which of the rings 2 is being driven, one of the electro-magnets causes intermittent actuation of a pawl 12 or 12<a>, which drives a pointer shaft 16. In the switch mechanism shown in Fig. 4, the circuits are connected to three insulated strips on a tongue 58, which is spring - controlled and is shifted from one groove 57<a> to another 57<b> by the spiral channel 57<c>. In each groove is a conducting-piece 61<a> or 61<b> which electrically connects one of the strips with one or other of the remaining strips according to which groove the tongue is engaging. In the form shown in Fig. 6, the pawls 35 actuated by the electromagnets are mounted on a lever 32 or 33 and drive a single spur-wheel 36 on the pointer spindle. Each lever has a projection 38 which engages the spur-wheel at each actuation and prevents overrunning. Fig. 8 shows a form of switch comprising a lever 25 pivoted at 25<a> and adapted to be rocked one way or the other by a cam-groove 24<a> engaged by an arm on the lever. Rollers on the lever ends run in a circular track containing pairs of contact strips 70, and these are bridged over momentarily at each revolution of the shaft 1. In other forms, the switch lever rocks into contact with switch jaws or with resilient contacts which are thereupon pressed against stationary contacts. In the form shown in Fig. 12, a switch arm 50 is mounted on the shaft 1 by means of a pin and spiral slot 51 so that it is shifted axially and bridges contact strips 47, 48 or 48, 49 according to the direction of rotation. The arm 50 may be driven, when shifted, by the pin or by the engagement of projections 53, 54. In another arrangement a pair of arms 50 are employed and these are mounted on the shaft by freewheel mechanism as in the case of the rings 2, Fig. 1. A damping arrangement for the pointer is described comprising a spring and a leather disk pressed against the face of the spur-wheel 36, Fig. 6. The indicator may be mounted in the usual engine - room telegraph instrument. According to Provisional Specification 3878/12, a motor driving the pointer may be controlled in direction by switches which are moved by cams on the shaft 1 and determine the direction of the current in the armature or field windings of the motor. The switch mechanism employed in this arrangement may be actuated by a pair of toothed collars, adapted to be moved axially one way or the other (and then to be positively driven) by a toothed member on the shaft.