US592308A - Milo g - Google Patents

Description

(N0 Modl.)

M. G. KELLOGG.

MULTIPLE SWITOHBOARD. I No. 592,308. Patented Oct. 26,1897.

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NlTED STATES FFICE,

PATENT MILO G. KELLOGG, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE KELLOGG SWITCIIBQARD AND SUPPLY COMPANY, OF SAME PLACE.

M ULTIPLE SWITCHBOARD.

SPECIFICATION formingpart of Letters Patent No. 592,308, dated October 26, 1897. Application filed July 16, 1888. Renewed December 2 0, 1890. Serial No. 375,311. (No model.)

To aZZ whom, it may concern.-

Be it known that I, MILO G. KELLOGG, of Chicago, (Hyde Park,) Illinois, have invented certain newand useful Improvements in Multiple Switchboards for Telephone-Exchanges, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to a telephone exchange system in which the subscribers lines are metallic-circuit lines connected to multiple switchboards and it consists in a system of testing at any board to determine whether any line is in use.

I place as many switchboards in the central office as are found necessary or desirable in order to. properly answer the calls and connect and disconnect the subscribers lines. On each board I place for each line a springjack or similar switch having two insulated contact-points which are normallyin contact and a third contact point or piece normally insulated from the others except by the line connections, said switch being adapted to receive a lo0p-switch plug and, when the plug is inserted, to disconnect the switch-points which are normally in contact and connect one of them to one of the contact-pieces of the plug and at the same time connect the other contact-piece of the plug with the third contact point or piece of the switch mentioned above.

The third contact points or pieces of the switches above described are so placed and arranged that an operator may at will apply a test-plug or similar device to them.

The switches of a line on the different boards may be calleda series of switches, and the test-pieces of a line may be called a series of test-pieces.

At each subscribers station is a battery which for purposes of testing should be in the circuit of his line when it is not in use and which may be in said circuit all of the time.

Figures 1 and l of the drawings are front views of sections of two multiple switchboards to which the same wires are connected. Fig. 2 is a diagram of the boards and the cir cuits and connections necessary to illustrate my invention. Fig. 3 shows a double or loop plug adapted to be used with the switches. Fig. 4: is a diagram of a subscribefs-station apparatus necessary to illustrate my invention.

In the drawings like parts and apparatus are indicated by the same letters and figures of reference.

In Fig. 2, A is a sectional view of the switchboard shown in Fig. 1, and A is a sectional View of the switchboard shown in Fig. 1", each as indicated by the line cl e.

a I) represent rubber strips, of the shape substantially as shown, on which the metal parts of the spring-jack switches are mounted. These strips may be of a length to receive any convenient number of spring-jack parts.

Z l, &c. are square holes through the fronts of and at the edges of the strips adapted to receive and guide the switch-plugs. The contact-springs g g, &c., are mounted to the rear of and are parallel to the holes Z Z, &c., to which they belong, as shown. The contactpoints it h, 860., corresponding to the contactsprings pass through the rubber strips, as shown, and are connected with the connecting-pieces 7t h.

jj are the contact-pieces of the switches,insulated from the rest of the parts except by the line-wire, each adapted to connect one side of its line to one of the contact-pieces of a loop-plug when inserted, and also to be the test-piece of its line at its board. The switchplugs are substantially as shown in Fig. 3.

The several parts mentioned above are so made, shaped, arranged, and adjusted that when a plug is inserted into any switch-hole it raises the spring in the rear of the hole from the contact-point, (on which it normally rests,) and the spring is connected to one of the contact-pieces of the plug, while the other contact-pieceof the plug is connected to the contact-piece j of the switch which is used. Each section of a rubber strip, with its contact-spring, contact-point, contact-piece, and

the hole, all arranged and operating as shown,

one plug at each board, and each plug connected to one side of its test receiving instrument by a flexible cord, as shown. The plugs and cords are so Constructed that the operators may at will bring the metal'tips of the plugs in contact with any contact-pieces at their respective boards.

In the subscribers-station apparatus shown in Fig. 4, 1 is the telephone-switch, 2 is the subscribers hand-telephone, 3 is the batterytransmitter, 4 is the primary of its inductioncoil, 5 is the secondary of its'induction-coil, and 6 is the transmitter-battery. The contact-points of the switch and the circuits aresubstantially as shown. The calling generator and bell are not shown, as they are not necessary to illustrate the operation of the test system. Line No. 1 andfline No. l represent the two sides or branches of the mej tallic-c-ircuit line of the subscriber. It will be seen that the battery is in the circuit of the line, as is also the battery-transmitter and primary of the induction-coil, and that when the telephone is off from its switch a short local circuit is closed, in which is the battery,

the transmitter, and primary of the inductioncoi-l, and that the battery therefore operates as a transmitter-battery. It also operates as a test-battery for its line, as will hereinafter appear.

The circuit of each subscribers line may be traced as follows: One branch, starting out from one side of the subscribers-station apparatus, is connected with all the contactpiecesjj or the switches of the line on the several boards. out from the other side of the subscribers-station apparatus, passes successively through the pairs of contact-points normally in con tact of its switches on'the several boards, be ing connected in each case to thespring g first. From the last contact-point h the line passes or is connected to all the test receiving instruments on the several boards on the other side of the instruments from what their test-plugs are connected. The connections, lineNo. 1* and line No. 1 in Fig. 2, are for the line ofwhich thesubscribers-station apparatus shown in Fig. 4 is a part.

The lines and the test receiving instruments are not normally; grounded,but the test receivinginstruments are open to the v groundat the central'oftice, andian accidental ground on the line tested between the sub-- scribers-station and the pairs of line-switch contact-pointswould not occasion, on testing, a false-signal that the line was free when it was switched at the centraloffice, as would be the case were the test receiving instruments'connectedwiththe: ground at the central office It is well known that such accidental grounds. are liable to occur on metal liccircuits, but in the system described above such a groundwouldnot affect the testing or otheroper-ation of; the system.

Itisapparent that eachline is normally The other branch, starting open at the central ofiice and that its battery is on closed circuit only when in use. It is also apparent that when a test-plug is applied to the contact-piece j of any line and the line is not switched there is a complete circuit through the line, the subscribers bat- 3 tery, back to the central office, and through the pairs. of contact-points of the switches of the line and the test receiving instrument to which the plug belongs, and the instrument being energized by thebattery will respond and indicate that the line is not in use. If, on the other hand, the line is switched at any 3 board, this test-circuit is opened at the pair of contacts at the board where the line is switched and the instrument will not respond. The operator will then know that the line is in use and will'not connect to it.

I have not indicated in detail the calling .apparatus or the operators answering and j connecting apparatus, as it is not necessary f to do so in the illustration of my invention, and well-known forms of apparatus can be used for them.

For the calling system an independentcall- 'ing-circuit common to many stations-such as theLaw or the American district systemmay be used.

I claim as my invention and desireto secure by Letters Patent I 1. In a telephone-exchange system,,a metallic-circuit telephone-line and a test receiv- ;ing instrument at the central office, said line' ,being normally connectedv at the central of- ;fice butnot elsewhere on one of its sides to one side of said test receiving instrumentand 1 open. on its other side to said instrument, and 1 said instrument being open to the ground in lcombinati'on with an electric battery at the subscribers station in the circuit of said line ;when it is not switched for conversation, a jswitching device to disconnect saidline from its normal connectionrwith said test receiving finstrument when the line is switched for conjversation, and a switch testing plug or device iadapted", at the will of the operator, to 0011- jinect said. instrument on its other side to the ide of said line normally open to it, substanjtially as set forth. I

2. In a telephone-exchange system, two'or j'more multiple switchboards at the central office, metallic-circuit lines connected to them ,and test receiving instruments, one ateach fboard, each line being normally connected at .jthe central office but not elsewhere on one of ga sides to each of saidtest'receiving instruiments, and said instruments being, open to fthe ground in. combination with electric batf teries, one in the circuit of each line at its subscribers station When-the line isnot switched ,for conversation, switching devices, one, at each board for each line to disconnect the ;line from its normal connection with said test :rcceiving instruments, and switch testing plugs or devices, one for each test receiving instrument, adapt'ed', at' the will of the oper ator, to connect its instrument on the other side to the normally open end of any of said lines, substantially as set forth.

3. In a telephone-exchange system, metallic-circuit lines and electric batteries, one in the circuit of each line at the subscribers station when the line is not switched for conversation, in combination with multiple switchboards for said lines at the central ofiice, test receiving instruments, one for each board, switches for said lines, one for each line on each board, each switch having a pair of contact-points normally in contact but opened to each other when its line is switched for conversation, one side of each line passing successively through said pairs of contact-points of its switches on the different boards and thence connected to one side of each of said test receiving instruments and not connected to it elsewhere, and said instruments being open to the ground, test bolts or pieces one for each line on each board and to each of which the other side of its line is connected, and switchtesting plugs or devices, one for each of said instruments and each adapted, at the will of the operator, to connect its instrument on the other side to any test bolt or piece located at its board, substantially as set forth.

4. In 'a telephone-exchange system, metallic-circuit lines, multiple switchboards for said lines and switches, one on each board for each line, in combination with test receiving instruments, one at each board, each instrument being open to the ground, and normally connected on one side to one side or branch of each of said lines, but disconnected from the line when the line is switched for conversation, and connected on its other side to a switch testing plug or device, adapted, at the will of the operator, to be brought into connection with the other side or branch of the line when the line is not in use, substantially as set forth.

In witness whereof I hereunto subscribe my name this 9th day of July, A. D. 1888.

MILO G. KELLOGG.

Witnesses:

MILTON HEAD, CALVIN DE WOLF.

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