Patent GB-170049-A (GB)
Title: Improvements in or relating to electric signalling systems
IPC: G08B5/22
Filed: 1920-06-10
Abstract: 170,049. Walker, C. L. June 10, 1920. Order apparatus.-In systems employing electromagnetic motors having a plurality of magnetic circuits for effecting step-by-step rotation, for example as described in Specification 137,255, the transmitter comprises a distributor having two distributive parts respectively connected with the positive and negative poles of a source of current, and the coils around the magnetic circuits are so connected up that one (alone or otherwise) constitutes a ' lead ' element, whilst a neighbouring coil (alone or otherwise) constitutes a ' return ' element, and means may also be provided for polarizing the magnetic circuits. Three magnetic circuits may be energized by pairs of coils A, B, C, Fig. 1<A>, connected by leads a<1>, b<1>, c<1>, to the brushes co-operating with the halves d<5>, e, of the distributor, which are respectively connected to the negative and positive poles of a source of current. The circuits A, B, C, are alternately strongly or weakly energized due to the coils carrying the whole or only half of the current according as the corresponding lead a<1>, b<1>, or c<1> is connected alone or in combination with another, to one half of the distributor. Polarizing coils energized by a battery h<5> may be arranged as shown, the effect of rotating the distributor being to increase, decrease or, in some cases, cancel the total flux; alternately the same battery may be used for both the transmitting and the polarizing currents. The polarizing coils may be connected up in series or in groups in parallel. In an arrangement, Fig. 2A, having four magnetic circuits polarized alternately in opposite directions, the distributor may have two equal segments producing energization in successive pairs, one segment may be of 90‹ producing energization singly, or of 135‹ producing energization of one circuit or of two neighbouring circuits alternately. Fig. 5 shows a section of a transmitter provided also with means for preventing a transmitter brush from making contact with both segments of the distributor at the same time and thus short-circuiting the battery. The distributing disc d<5>, e, for example, of phosphorbronze, assembled in one piece with a coarse cut i and finally divided by fine oblique saw-cuts k, Fig. 6, is mounted on the insulating tube g<1> between insulating discs g<2>, g<3>, for example, of bone and the two segments d<5>, e, respectively are connected by screws in a conducting manner to the flanges carried by phosphor-bronze tubes g<6>, g<7>. Contactual members a, b, c, m' of flexible material having flattened rivets preferably of platinum act as brush leads for the three contacts on the distributor disc and for the two supply leads. The spindle g is driven from the shaft p<11> through a spiral spring p<2> and carries at its other end a wheel y on which are mounted, on transverse spindles r<3>, two pivoted arms r<4> connected together by a spring s<2>. Balls r<2> on the arms r<4> engage with circular studs or rollers t<1> arranged in a ring, thus causing a momentary stoppage in the rotation of the spindle g after which stoppage the balls overcome the force of the spring and dart over the studs causing a corresponding quick movement of the break in the distributor disc over the brush member. Above a certain speed the balls swing out clear of the studs until spurs at the other ends of the arms r<4> engage the edges of holes q<1> in the wheel y. Specification 142,211 is referred to, and in one Provisional Specification,. Specification 137,150 is also referred to.