US1689340A - Selector switch - Google Patents

Description

J. F. HEARN SELECTOR SWITCH Filed Nov. 14, 1925 Patented Oct. 30, 1928.

' UNITED STATES 1,689,340 PATENT. OFFICE.

JOHN I. ERA-RN, OF NEWARK, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COH- rm, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

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Application filed November 14, 1923. Serial No. 674,637.

The object of this invention is to provide means of constructin and adjusting an improved selector switc of simple and inexpensive construction for use in automatic I telephone systems in various capacities, such as a line finder, line switch, or register.

In switches of this general type such as are shown in the patents to Dietl No. 1,126,727 (February 2, 1915) and to Adams No. 1,399, 728 (December 13, 1921), considerable difliculty has been encountered due, to uneven wearin of the terminals, necessitating the discarding of the entire switch.

A feature of this invention, is the arrangement whereby the rotor may be readily removed and replaced, without requiring the readjustment of the various contacting members of the terminal bank and the rotor.

Another feature of the invention is the substitution of an abrasive wheel for the brush assembly for rinding the terminals to align them in a perfect cylindrical surface.

Another feature of this invention is the construction of the terminals in a separate unit apart from the stationary element of the switch, whereby its useful life is considerably increased.

Other features will appear from the detailed description.

Fig. 1 is a side view of the switch, Fig. 2 is a section 22 of Fig. 1, and Fig. 3 is a section of the switch similar to Fig. 2 but with the brush assembly replaced by an abrasive wheel.

The individual terminals 1, are arranged in the form of the arc of a circle and molded in the molding compound 4 in units, each layer forming one unit, and a number of these units, usually six, are encased in the casing 10 by means of the screws 11. The terminal arc is then ground by means of a suitable grinding wheel in order to align the contacting surfaces of the terminals in the same cylindrical plane. The encased terminal bank is then secured to the main frame 6 by means of the three screws 5.

The brushes 9 are secured at 7 by means of rivets to the backstops 22 which form a part of the metal carrier 8 which electrically connects the individual brushes of each pair of brushes together. Each pair of brushes 9 is connected to a separate carrier 8, and all the carriers are insulated from each other and mounted upon the shaft 12 to form a rotary unit or rotor.

The usual driving unit 13, consisting of an electro-magnet 14, with its armature 15, pivoted at 23, carrying the arm 16, to which is secured the pawl 17 for stepping the ratchet 18, is attached to the main frame 6 by means of the screw 21. The ratchet 18 which is stepped by the pawl 17 forms a part of the rotor, hence each time the pawl 17 makes a complete stroke, the ratchet 18, and consequently the rotor, rotates one step in a counter clockwise direction. To prevent the rotor from rotating in a clockwise direction the pawl 19 is provided, which normally engages with one of the teeth of the ratchet 18.

The back stop 20 limits the upward motion of the pawl 17, thus preventing the rotor from stepping more than one step at a time. A spring 26 is tensioned between the lug 25, forming a part of the magneticlstructure, and a lug 27 which is an extension of the armature 15. When the armature 15 is attracted by the electromagnet 14 the lug 27 is moved away from the lug 25, thus tending to increase t e tension of the spring 26. The pawl 17 'is also brought into engagement with the next successive tooth of the ratchet 18, and when the electromagnet 14 is deenergized the spring 26 tends to return the armature 15 to normal, thus forcing the pawl 17 to step the rotor one step.

To make the stepping magnet 14 self-interrupting, the arm 16 in operating causes the insulating cap 28 to force the contact spring 29 away from the contact member 30, thus opening stepping magnet circuit.

Each brush 9 is split into two prongs 31 and 32 thus insuring a better contact between the brushes and the terminals.

When the rotor is in motion the brushes 9 step from terminal to terminal until they pass between the feeder brushes 24 and 33. The feeder brushes, however, are so arranged that the brushes 9 do not make physical contact with the feeder brushes in passing them.- The feeder brushes, however, do make constant contact with the carrier 8 and as this pressure is constant, the double load condition, experienced in other switches of this general type, is eliminated.

The bolt 34 (Fig. 6) locks the latch 3 which when in the locked position bears against the groove 35 in the shaft 12 thus holding the rotor in position. When the bolt 34 is loosened, the latch 3 which is shaped like an eccentric cam may be turned B loosenin the three screws, 5 the termi-- nal ank may e removed and re laced without disturbing the other mem ers of the .switch in any way.

Inother switches of this general type, the terminals have of necessity been composed of very thin sheet metal, and, since the terminals are worn away by the friction of the brushes, the life of the terminal bank has been relatively short. In. the present invention, due to the heavy weight of the metal used, and the length of the terminals, which may be worn down until almost flush with the insulating compound, it is evident that the useful life of the switch is considerably increased.

Due to the ease with which the rotor and feeder brushes may be removed and the weight of the meta used for the terminals comprising the terminal bank, it is ossible to remove the rotor and feeder brus es, replacing the former by a small grinding element such as is shown in Fi 3 of the drawings. This element comprlses a shaft 37 upon which is mounted a circular grinding disc 36, of a width slightly greater than the breadth of the terminal assembly. When the shaft 37 is mounted in the switch frame in place of the brush mounting and the switch rotated, the terminal faces are ground thereby aligning them into the same cylindrical surface. Disc 36 may be of any diameter according to the curvature of the terminal are desired.

What is claimed is: Y

1. A method of constructing a terminal bank fora rotary switchwhich consists, in assembling a group of insulated terminals 1n a layer in t e general form of the arc of a circle to form a unit, of securing a plurality of the units together to form a bank, of assemblin a grinding unit in the place of the rotata 1e switch member, and of rotatmg the grinding unit for grinding the ends of the terminals thus assembled to produce a plurality of contacting terminal ends 1n the same cy indrical surface.

2. A method of constructin a terminal bank for a rotary switch whic consists, in securing a group of individual terminals together, moulding the terminals together as no unit with a suitable moulding and'insulating compound of securing a lurality of the units toget er to form a bank, of assembling a grinding unit in the place of the rotatable switch member, and of rotating the grinding unit for grinding the ends of the terminals thus assembled to produce a plurality of contacting terminal ends in the same cylindrical surface.

3. Method of re-alignin the contactin surfaces of the terminals 0 a terminal ban of a selector switch which consists in replacing the rotatable member of the selector switch by a grinding wheel and of rotating the grinding wheel by a suitable driving means, thus grinding the contacting surfaces of the terminals to align them all in the same cylindrical lane.

4. Method of re-a igning the contacting surfaces of the terminals of a molded terminal bank of a selector switch, which consists in replacing the rotatable member of the selector switch by a grindin wheel and of rotating the grinding wheel ymeans of the selector stepping magnet, thus grinding the contacting surfaces of the terminals to ge-align them in the same cylindrical surace.

In witness whereof, I hereunto subscribe my name this 12th day of November A. D.,

JOHN F. HEARN.

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