Patent GB-190227850-A (GB)
Title: Improvements in and connected with the Electric Lighting of Railway and other Carriages and the like
Inventor: HALL ROBERT FREDERICK
Filed: 1902-12-17
Granted: 1903-12-17
Abstract: 27,850. Hall, R. F. Dec.17. Casings; dynamos, regulating; field magnets. -Relates to train lighting and like systems in which an automatically - regulated compound-wound dynamo is driven from a car axle, a single set of accumulators supplying the current when the dynamo is not running. The regulation is effected as the speed increases by inserting resistance in the field circuit, by connecting up demagnetizing-coils around the field magnets, and by introducing resistance into the lamp circuit. Switches are provided for maintaining the direction of the current constant though the direction of the train is reversed, for cutting in or out the dynamo when the speed rises above or falls below the limit, and also for cutting out the dynamo should the accumulators be fully charged. Switches and coupling-devices are also provided for connecting up testing-instruments to ascertain the working of the dynamo &c. Fig. 1 shows the dynamo and its accessories within the casing 36, 37. The armature 30 is mounted on the shaft 31 supported in bearings 34, 35 suitably suspended from the carriage frame. The shaft carries the driving-pulley 32, and the commutator 41 engaging the brushes 42, and at the other end it is fitted with tubes provided with carriers and projections 117, 118 for operating the rocking-switch 96 for maintaining the current direction constant. As the speed of the shaft increases, the carriers 115,116 of the projections are thrown outwards by centrifugal action, and thus the switch limb 123 is not continuously struck by the projections. The switch contacts for cutting in or out the magnetizing-coils consist of V-shaped plates 43<x>, Fig. 2, strung on a bar 48 carried by the casing, the contact-plates being separated by insulating-plates. The sliding contacts 53, which normally shortcircuit the coils, are carried by a rod 55 attached to an arm 56 of a sleeve sliding on the shaft. The sleeve 86 is moved along the shaft by a centrifugal device 81, 82, Fig. 1, as the speed increases, and the contacts 53, Fig. 2, are moved to insert the demagnetizing-coils in the field. The sleeve also serves to operate a switch 60 for inserting resistances 63 in the field coils, and also a third switch for inserting the resistances 72 in the lamp circuit. These are all so proportioned that the current is substantially constant over wide ranges of speed. Springs 94, 95, Fig. 1, are arranged to return the sleeve as the speed falls. For adjusting the dynamo for summer and winter loads, a variable resistance is provided in the shunt field. Fig. 28 shows the relative arrangement of the circuits, regulating-appliances, &c. ; 41<x> are the field coils with resistances 63 ; 42<x> the demagnetizing coils ; 102 the reversing -switch ; 128, 129 the automatic switch for cutting in or out the dynamo ; 72 the lamp resistance controlled by a switch having contacts 130, 131 ; 140, 142 the summer and winter load adjuster ; 147, 148 the electromagnetic switch for preventing overcharge of the cells ; 153,156 the testing-terminals ; and 167<x> the switch for varying the number of lamps in the circuit. In a modified arrangement, the resistances in the field may be cut in or out by the same slide that controls the demagnetizing-coils, the two sets of contacts being mounted on one carrier rod, and the slide being correspondingly constructed. In another modification, the lamp resistances may be controlled directly by the switch 128, 129, only one slide being required.