Patent GB-190710786-A (GB)
Title: Improvements in and relating to Electrical Signalling Systems and Apparatus therefor.
Filed: 1907-05-08
Granted: 1908-01-16
Abstract: 10,786. British Thomson-Houston Co., [General Electric Co.]. May 8. Signals, time-alarm.-In an order telegraph for indicating to each furnace room from the engineroom of a steamer the time for firing each furnace, a transmitter, indirectly operated through electromagnetic devices by a constant-speed electromotor, controls the step-by-step magnetic-field motors of the receivers. A rotating disk 13 pivoted at O, and geared down from the motor carries a fixed contact-piece 14 which once every revolution of the disk touches the fixed contact 15, whereupon the electro-magnet 16 is energized and its armature 17 is attracted. A pawl carried by the armature 17 and acting in conjunction with a retaining-pawl engages a ratchet-wheel (not shown) pivoted at A so that at each oscillation of the armature the ratchet-wheel is advanced against the force of a spiral spring. The ratchet-wheel is advanced until a conducting projection 23 on the wheel engages with the fixed contact 32, when a circuit is closed through the coils of the electromagnet 33, the armature 34 of which is thereupon attracted and lifts both the driving and the retaining pawls out of engagement with the ratchet - wheel, allowing the latter to move backwards under the force of its spiral spring to a position determined by the position of an adjustable fixed stop 24 with which the projection,23 engages. The time-interval between successive signals is thus dependent upon the position of the stop 24. The electro-magnet 33 remains energized although contact has been broken between the members 23, 24, as a second contact has been made by the contact 36 on the armature 34 engaging with the contact 37 on the armature 17, and the circuit through the magnet 33 is not broken until the armature 17 is again energized, when the contact 37 is withdrawn from engagement with the contact 36. The armature 34 actuates a pawldriven ratchet-wheel to which the commutator 44, having alternating conducting and non-conducting segments, is attached. As signals are. to be sent alternately to the port and starboard furnace room, two brushes 45, 46 bear on the surface of the commutator, and the motion of the commutator is such that the brushes rest alternately on a conducting and non-conducting segment. When the brush 45 corresponding to the starboard receiving-instruments is on a conducting-segment of the commutator (the brush 46 being at that moment on a non - conducting segment), a circuit is completed through the electromagnet 62 of the receiving - instrument, the armature of which is thereupon attracted, closing a circuit through a warning bell and a group of lamps 67. The commutator 44 at the transmitting-station carries with it a disk carrying contacts which engage with the rings 72, 49, 50, the divided rings 49, 50 corresponding to the port and starboard receiving-instruments. All of these segments of the rings 49, 50 are connected by separate wires to the receiving-instruments, and the contact arrangements are such that one of the segments of a ring is successively put in communication with the positive main while the other two are connected to the negative main, so that when the contacts 36, 37 are in engagement the circuit is completed through the magnets 58 of the. motor mechanism at the receiving-station, the whole current passing through one of the coils 58 and then through the other two in parallel. As the commutator at the transmitting-station is continually altering the distribution of the current through the magnets 58, the constantly-energized armature 67 which carries the signal disk is thereby caused to rotate. The motor which drives the contact-wheel of the transmitting-instrument has an unwound armature consisting of two fivepointed star-shaped pieces which revolve close to the opposite poles of four straight electro-magnets 1, which are successively energized. The armature shaft carries a commutator 3 consisting of a pentagonal conducting plate set in staggered relation to a similar insulating-plate. The four brushes 4 corresponding to the four electro-magnets 1 engage with this commutator. A metal disk keyed to the motor shaft rotates between the poles of an electro-magnet 7 and acts as a Foucault brake. The strength of the field of the magnet 7 may be adjusted by means of a resistance, and the torque may also be separately adjusted by means of resistances placed in series with the field magnets of the motor. The constantly energized armature 57 of the step-by-step magneticfield motor of the receiving instrument-consists of an S-shaped piece round the middle horizontal part of which the energizing coil is placed. The poles of this armature have a fan shape. The armature rotates in front of the three or more electromagnets 58, the polarity of which is being constantly changed during the operation of the instrument by the commutator of the transmitter. Specification No. 180, A.D. 1906, is referred to.