GB275942A - Improvements in or relating to light signals - Google Patents

Abstract

275,942. General Railway Signal Co., (Assignees of Field, 0. S.). Aug. 10, 1926, [Convention date). Oscillating machines; electromagnets.-In a signal lamp, coloured spectacles or other screens 4 are clipped to a member 107 mounted on a polar vane 78 of a threeposition motor element in which a field coil 75 is mounted on a core 71 secured to two polepieces 69, 70 by means of tapered threaded plugs 73, the polepieces 69, 70 being adapted to coact with polar vanes 77, 78 connected by a core 76, preferably of Norway iron, provided with an energizing winding 79 carried in an insulating shell 80. The armature structure is supported by bracket castings 83, 84 mounted on the pole-shoes 69, 70. Deformed washers 88 may be located between the pole-shoes and the rear bracket 84, which is insulated from the casing 9. The core 76 has shaft extensions 93, 94 with turned ends 95, 96 adapted to roll on balls 99 in bearings 97, 98 locked to the brackets 83, 84, and provided with movable end plates 104. The polar vane 77 carries a member 110 equipped with hardened rollers 112 which are carried by pivoted bellcranks 113 so that their distances from the axis of rotation of the armature can be slightly adjusted, and they can be locked in position by a screw 115. The rollers 112 are engaged by ears extending from a pair of hinged balance weights 117, the movement of which is adjusted by means of stop screws 123. The polar vane 77 is provided with a central weight 110<a> to compensate for the weight of the spectacles 4 and member 107, and the outward movement of the armature and spectacles. is controlled by adjustable stops 124 engaging ears on the armature member 110. A fly-wheel 94<a> is loosely mounted on the shaft extension 94 and is held in frictional engagement with a shoulder 95<a> by a spring 96a so that, when the ears on the armature member 110 strike the stops 124, the flywheel will slip slightly and prevent rebound of the armature assembly. The counterweights 117 carry insulated fingers 127 adapted to make contact with a pair of front and back contacts 128, supported by a bar 130 from the pole-shoes 69, 70. The fingers 127 and contacts 128 are electrically connected to terminals 132 which are wired to two of a series of terminals 135 carried on an insulating panel 134 on the outside of the mechanism casing 9, which is also provided with a glazed inspection aperture 138. The field coil 75 is continuously energized but the balanced structure causes no torque on the armature and the central red glass is held coincident with the beam of light. Either the yellow or the green glass is brought into alignment according to the direction of now of the current when the coil 79 is energized. In order to produce, as even a torque as possible, the poleshoes 69, 70 are given a deformed curvature 155, the distance from the axis of rotation to the poleshoes increasing towards the tips of the poleshoes.