Patent GB-347739-A (GB)
Title: Improvements in and relating to electrical devices for indicating the direction of rotation or of movement of a machine part
IPC: G01P13/04
Filed: 1930-01-28
Abstract: 347,739. Revolution-direction indicators. GRAHAM & CO., Ltd., A. and VAUGHAN, C. H., St. Andrew's Works, Slough. Jan. 28, 1930, Nos. 2905 and 20774. [Class 106 (iii).] Comprises three contact makers arranged to be actuated successively and repeatedly by means carried by the revolving shaft or body and in different orders according to the direction of movement of the shaft, the contact makers controlling three circuits with one of which is associated switching means controlling two additional circuits each having a lamp or indicating means operated according to the order of rotation of the contact makers. The movable contacts 1, 2, 3 operated against the influence of springs d are mounted in a casing a on a fixed support b and having mounted opposite them fixed studs or polepieces e, e<1>. Fixed to the shaft c are three sets of permanent magnets 1a, 2a, 3a. The contacts 1, 3 are normally held open by their springs while the contact 2 is normally held closed. The three movable contacts are connected to the +ve pole of a source of supply. The winding f of a relay is connected at one end to the stationary contact 1b of the contact maker 1, and at the other end to the - ve of the supply. The armature lever g of the relay is connected to the contact 3b of the contact maker 3 and carries two contacts h, i of which the former normally bears against a contact h<1> in a signal circuit k and the other i is arranged to bear against a contact i<1> in a signalling circuit k<1> when the lever is drawn by the core #<1> of the relay against the influence of the spring. Arrows r, r<1> are illuminated by lamps s, s<1> in the signal circuit. When the shaft rotates so that the contact makers are operated in the order 1, 2, 3 each time the magnet 1a passes the fixed poles e, e<1> the contact 1 is moved to establish a circuit from +ve through the relay f, the lever g breaking the contacts h, h<1> to disconnect the signal circuit k and move the contact il to engage the contact i<1>. The relay is energized via the contact maker 2 after the magnets 1a have passed out of inductive relation to the pieces e, e<1> of contact maker 1. Contact maker 2 will next be opened by the magnet 2a passing, the relay will be de-energized and the lever g returned. When the magnet 3 passes the contact maker 3 is closed and the circuit k established. When the shaft rotates in the opposite direction the contact makers are operated in the order 1, 3, 2, the relay f is energized as before and continues energized via the contact maker 2, but as the contact maker 3 is operated next, the circuit k<1> is established. As in each case the circuits k or k<1> will be closed and opened during the rotation, by watching the fluctuations of the lamps the speed can be determined. Speed counters t, t<1> may be actuated. The contact makers are held out of use when so desired by magnets ul, u<2>, u<3> brought into play by operating a switch v. In a modification, the device is adapted to indicate the direction of movement of a body having rectilinear movement such as a lift cage.