US2330812A

US2330812A - Selector switch

Info

Publication number: US2330812A
Application number: US433315A
Authority: US
Inventors: Deakin Gerald
Original assignee: International Standard Electric Corp
Current assignee: International Standard Electric Corp
Priority date: 1942-03-04
Filing date: 1942-03-04
Publication date: 1943-10-05
Anticipated expiration: 1960-10-05

Description

Filed March 4, 1942 8 Sheets-Sheet 1 INVENTOH. wfu /Z'A/r//V ATTORNEY oct. 5, 1943. G. IDI-:NGNv 2,330,812

SELECTOR SWITCH Filed March 4. 1942 8 SheeI.S-Shee1'l 2 Q R o N N N Q I I '"`l .I II-II-II waff-333753:.- I I :"::I IIILl III III I I I I I I I I I I I II II I I l I I I I I I I |I I I I I I I I I I I I II II I I I l I I I I I I I I II II I I I I I I I I I I II I I I I I I I I I I I 1| I I I I* I I I l I I II I'II" V'III'IV "I I I I I I I I I 5 I I I I I| "IIQII "'.}I} II I I I I I I I I I I I I c; I I E I I I I I I I I I I :I I I I II 1 Il II I I l I I I III/ I II i TEILE I* I l IIIIli @I II.. In! um I IIIIII II III @I I N VE N TOR. @ER/a fA/r//v Q Q gli ITOREY.

oa. 5, 1943. G. DEAKIN 2,330,812`

SELECTOR SWITCH Fied Mach 4, 1942 a sheets-sheet s 1N VENTOH. 627ML Dfw/mv Oct. 5, 1943# G. Dl-:AKIN

SELECTOR SWITCH Filed March 4. 1942 8 Sheets-Sheet 4 Nn R. WNS E NW, .WW

hun.

m/W//VM INVENTOR. '-/MLD fA/r/A/ ATTORNEY.

Oct. 5, 1943. G'. DEAKlN SELECTOR SWI'i'CH Filed March 4, 1942 l 8 Sheets-Sheet 5 nm. I A

INVENTOH. BY f/QALP en/mv ATTORNEY.

O Ct- 5, 1943 G. DEAKIN l 2,330,312

SELECTOR SWITCH Filed March 4, 1942 8 Sheets-Sheet 6 NIII'IMN IN VEN TOR. QERALD .AK/,V

n ATTBRNEY.

oct. 5,'1943.

lllllllll G. DEAKIN SELECTOR SWITCH Filed March 4, 1942 8 Sheets-Sheet 7 Oct- 5, 1943- G. DEAKIN 2,330,812

SELECTOR swIT'cH Filed March 4, 1942 8 Sheets-Sheet 8 FIG.19.

I N VE N TOR. l SER/11.0 DEA/27N ATTORNEY.

Patented Oct. 5, 1943 SELECTOR SWITCH Gerald Deakin, New York, N. Y., assigner to International Standard Electric Corporation,

New York, N. Y., a corporation of Delaware Application March 4, 1942, serial No. 433,315 17 Claims. `(Cl. 179-2753) This invention relates to selector switches of the kind used in telecommunication systems, for example, automatic and semi-automatic` telephone exchange systems, as finder switches, group selectors, final connectors, marking switches or the like.

An object ofthe invention is to produce a switch which is robust in construction, is cheap to manufacture and easy to assemble and will operate satisfactorily over long periods of service with a minimum of attention.

A further object of the invention is the provision of a switch which is dust-.tight and which is particularly designed to resist the effects of moisture and humidity.

A san further object is .the provision of a.

switch in which the main supporting framework and other non-metallic parts are formed of plastic moldings which are molded tot together accurately without adjustment when the parts are assembled. Moreover, no internal wiring or soldering is required when the switch is assembled. More particularly, the main switch frame member comprises a unitary plastic molding which supports the terminal b ank, the driving shaft, the bearing shaft for the brush carriage, the driving clutch magnet and means for accurately locating and maintaining the various shafts and bearings in position. By this means exact relative alignment of the various parts is obtained in a relatively simple manner. Y

Another object is the employment of a single unitary molding for supporting all the mechanism of a plurality of selectors. In the example to be described in detail, three selectors are supported by a common plastic molding and enclosed within a single box-like dust-tight housing, but obviously a larger number of selectors may be grouped in this manner. The unitary molding supports the terminal banks-of the three independent selectors. This construction lends itself to the employment of a simple method ofmultipling using ribbon cables. A flat terminal bank is provided and all terminals are extended at the rear to a suilicient distance to permit multipling by the use of a simple form of ribbon cable. One third of the terminals are extended beyond the ribbon cables and separated therefrom by a strip of insulating material, the extended parts thus providing a terminal strip with ample space around the terminals for eflecting soldering or welding side cables.

The above and other objects and features of ',he invention will be u nderstood from the followoperations to outing description taken in conjunction with the attached drawings in which:

Fig. 1 is a Ulan view of a selector mounted on its bay;

Fig. 2 is a front elevation of a unit of three selectors;

Fig. 3 is a section on the line 3 3 of Fig. 1;

Fig. 4 is a section on the line 4 4 of Fig. 3;

Fig. 5 is a section on the line 5 5 of Fig. 3;

Fig. 6 is a section on the line 6 6 of Fig. 5;

Fig. 7 is a sectional View of the terminal bank;

Fig. 8 is an end elevation and section on the line 8 8 of Fig. 9 with the lower end of armature 81 removed; I

Fig. 9 is a side elevation and section on the line 9 9 of Fig. 8; Y

Fig. 10 is a detailed view of a rubbing brush assembly;

Fig. 11 is a detailed view of a rubbing brush for the brush magnet feeders;

Fig. v12 is a detailed view of the centering contact assembly;

Fig. 13 is a detailed view of the mechanism for laterally shifting the brushes and is a section on the line I 3 I3 of Fig. 9;

Fig. 14 is an end elevation of a modied selector provided with a tilting bar for forcing the brushes onto ,the bank terminals;

Fig. 15 is a side elevation;

Fig. 16 is a detailed view of the non-rubbing brush assembly;

Fig. 17 is an end elevation of the mechanism for rocking the tilting bar;

Fig. 18 is a side elevation of this mechanism; and

Fig. 19 is a perspective view of a frame molding.

As will be evident from the drawings, the se`- lectors are manufactured and assembled in units comprising three selectors. Each such'unit or tri-selector consists of a unitary molded plastic frame I, Figs. 1 to 7 and 19 in which are molded the bank terminals 2, the feeder strip "jack in springs 3, the home contact assembly 4, insert screws 5 for the bay mounting, ins/erts for cover retaining screws 6, inserts for the screws securing'the clutch magnets 1, inserts for screws 8 securing the feeder blocks 9,*grooves |30 into which may be slipped feeder blocks 9, worm shaft bearings I0, main bearing shafts II, home contact rocker shafts I2, and brush carriage .tilting rod I3 (Figs. 14 and 15) when used. In addition to the main molded frame I. each tri-selector has two sheet metal sides I4 which slip into grooves II'I in the ends |33 of the molded frame i and into grooves II'I in the base I34 of the molded frame and a transparent lcover I5 secured by four screws 8 to each end of `the molded frame I.` Between this trans- I 'parent cover l5 and the upright ends of frame I at each end are two rubber gaskets I8 or their equivalent, the purpose of which is to make the tri-selector dust-tight. There are no wires inside the selector. The cover I5 may be sealed in position by two wires piercing two of the holding screws 8 at each end of the selector and sealed at I1 (Fig. 1) in any convenient manner, the intention being that the sealing tool will ,I be under lockand key in the hands of some one Referring Aparticularlybut not exclusively, to

Figs. y8 to 13, Fig. 8 is a cross-section of that part of the base o'f frame I belonging to one'selector and showing a side view of the bank terminals 2.

serious damage can take to brush shift member 23 by screws 24. Piercing the member 28 are the bronze contact shoes 29 secured against lateral movement by slots 39 in member 28 and against longitudinal movement by toeing into snug fitting holes 3i in the member 28. The contact shoes which are rounded and broadened at the contact end are of hard phos- Fig". 9 is a side elevation of a section of the base I andan edge view of the bank terminals 2. Four sets of terminalsv are shown in Fig. 8, viz. A, B, C, and T. Two of each are shown since the selector hunts over one row moving in one direction and over'the other row when moving in the opposite direction. How this is done will be described later` on. Terminals? A, B, and C are Athis small piece of metal is clipped off, thus separating the terminals electrically. .Terminals A, B, and C are known as the non-rubbing precious metal terminals since the corresponding brushes are not in contact with them when the switch is in motion.

Terminals T over which the corresponding brush rubs while the switch is 'in motion are punched from a strip of bronze of the proper dimension. The rubbing edge of the terminal is rounded to reduce wear to a minimum.

The imbedded .part of all terminals are notched so as to prevent a terminal from being forced out after molding, or displaced.

The brush carriage contacts are shown in Figs.

'8, 9, io, 14, 15 and 1c. The non-rubbing brushes consist of two hat strip springs I9 and 20,Figs. 9 and 16. Spring I3 -is bent U-shaped and the lower arm is slotted into two prongs with silver tips 2| on the lower side. Springs I9 and 20 have silver tips 22. The two springs are attached to the brush shoe shift block 23 by screws 24. Figs. 8 and 9 show the brushes in the position they assume when the brush carriage is in motion. The silver contactsdo not rub.' When the selector is at rest, plunger 25 (see Fig. 16) forces the two .silver tips 2I against the silver tops I8 of -the selected bank terminals and silver tips 22 against the strip 32, thus a substantiaLdoubIe contact and high pressure connection is made between the xed feeder strips 32 and the xed bank termiy silver edge 28 of the feeder l the terminals.

phor bronze. They press against feeder strip 32 at the top and thev terminals 2 at the-bottom under the tension of band springs 33, also secured to the brush shift member 23. When brush 29 passes from one terminal 2 to the next, it is pressed downward until the shank of the' shoe rests incontact with the inner surface 28, thus limiting the downward motion of the shoe. The

design is such that under this condition `the shoe cannot short-circuit two adjacent terminals while passing from one to the other. To insure accu- The metal feeder strips 39 and 32 are molded in feeder blocks 35 and 38, Fig. 8. There are two feeder blocks p'er selector or six per tri-selector, Fig. 3.- The feeder blocks are accurately molded and fit into grooves |39 and shoulders 31, molded in the upright ends of frame I. 'I'hey `are held in position by screws 8 and clamps 38, Figs. 5 and 6. When the molded feeder blocks -35 and 38 are secured in position, the lower feeder strips 32 make electrical contact with jack springs 3 molded into and projecting through frame I. The upper feeder strips'39 also make contact with the similar springs 3 but at theother end of the frame, Figs. 3 and 5. To enable all wiring to be brought to one end of the selector, grooves 40 are molded into the base of frame I, Figs. 3 and '7. No wires pass over or across the ribbon cable or through the inside of the selector.

Feeder strips for the A, B, andC brushes are of brass with a silver edge. The remaining feeder strips are of strip bronze and the brushv shoes 29, 49, and 5I making contact with them,

are rounded and, where necessary. bumped `tor with a brush magnet have six silver edged feederstrips for the non-rubbing A, B, and Cv brushes, two bronze strips for the rubbing T brushes, two bronze strips for the clutch brushes 5I` and one bronze strip for the ground brush 49. When the brush carriage magnet is replaced by a tilting bar, one ofthe clutch feeder strips may be omitted as shown in Fis. 1.4.

Details of the rubbing clutch brush assembly is shown in Fig. 11. The assembly comprises the brush shoe 5I with a flattened and rounded point bearing on the feeder strip, band spring 52 forcing shoe 5I against feeder strip, and part 53 into which is toed the brush shoe 5I at 54 and secures it against longitudinal movement. The whole is secured to the brush carriage I8 by a screw 55. Slot 58 in the brush carriage through which the @brush shoe 5I projects prevents lateral motion net spring 42, a pivoted lever 48 insulated from but controling spring 42 through insulator 51, and a pivoted lever brush shoe 49 making contact between ground feeder strip 39 and spring 4|. Both 48 and 4,9 are secured to the brush carriage 18 by pivot 43, in turn held in position by part 44 of spring nest 45 which is secured to the brush carriage by screw 46. Molded into feeder block 36 is a series of grooves 41 accurately spaced with relation to the corresponding terminals 2 on the base below. As the brush carriage advances, lever 48 moves up and down, causing contact to be made between contact points 58. Ground shoe 48 does not change its position with respect to the brush carriage in a perfect selector. However, should there be a slight variation in distance between the brush carriage and the surface of the feeder strip, as the brush carriage advances lever 49 follows the changeand thus maintains the proper relationships between springs 4| and 42. The adjustment of the centering contact is such that the circuit of the clutch magnet is opened for approximately 65% of the time and closed when the brushes are between bank terminals for 35% of the time, the center of this period being midway between bank terminals.

Motion is imparted to the brushv carriage 18 by a continuous thread molded worm 51 secured to steel shaft 58, Figs. 8 and 9. The steel shaft 58 is supported at each end by a self-oiling selfaligning spherical bearing I0, Figs. 2 and 3. These` bearings rest in accurately molded slots |35, Fig. 19 in the upright ends |33 of the frame I and are secured in position by molded plugs 59. 'The seatings in the slots `and the ends of the plugs 59 are cup-shaped. Similar plugs 80 and 6| secure the main bearing shaft Il and home contact rod |2 respectively in position 'see Figs. 3, 4, and 19). Motion is imparted to the shaft 58 by a clutch mechanism comprising' clutch magnet 1, Fig. 2, which, whenenergized, allows molded driven cone 62, keyed to but free to slide on shaft 58, to be forced against driving disc 63 under tension of spiral spring 64, one end of which rests on shoulder 85 on shaft 58 and the other end against the bottom of the molded slot in cone 62 (see Fig. 5). To prevent the cone from wobbling, extension 66 of shaft 58 acts as an outboard support. Normally, armature 51 of the clutch forces cone 62 back against a rubber or similar'stop 68, Fig. 2, under the tension of a wire spring 18, thus holding the threaded worm and consequently the brush carriage in some fixed position. The clutch armature 61 is forked at the upper end 1| and thisI fork fits loosely into groove 68 of the cone 62. Armature B1 is not in contact with cone 82 when the latter is rotating. The width of slot 69 and the movement of armature 81 are adjusted accordingly.

Teeth or ribs 12 are molded in the end of cone 62. The driving disc 63 is of leather, rubber. or other semi-hard material. The pressure of spring 64 forces the sharp ribs 12 of the cone jections 15 of frame Space 11 betweenAprojections 16 and below the clutch magnet 10 provides space for the condenser forming part of the spark quenching circuit of the coil magnet. The wires from the clutch magnet are brought out along the base of the selector in grooves 40 provided for the purpose.

The brush carriage consists of a molded frame 18, Figs. 8 and 9, of a rather intricate form. It has two main self-oiling bearings 19 arranged to slide on the main supporting shaft l| which shaft, as previously indicated, is secured at each end in slots molded in the frame of the selector. 'I'he brush shift supporting member 80 is attached to the main part of the molding by thin strip 8| which moves in the gap between the two

feeder blocks

35 and 35. one and the same molding. To guide the brush carriage when in motion, self-oiling parts 82 inserted in molded part 8| rub against slide elevations molded in the sides of feeder blocks 35 and 36 (see Fig. 9).

Motion is imparted to the brush carriage 18 whem he continuous thread worm 51 is rotated due to the meshing of hardened steel shoe 83 with continuous thread 84. Shoe 83 is forced into position by the pressure of spring 85 which rests in a hole molded in brush carriage 18. The arrangement assures the absence of back lash.

In Figs. 8 and 9, the brush plunger 25 is controlled by a brush carriage magnet 88 which, whenr energized, attracts armature 81 causing plunger 25 to move outward, allowing the A, B, and C brushes to disassociate themselves from bank terminals. Plunger 25 does not engage the T brushes. When the magnet is deenergized, plunger 25 assumes the position shown in Fig. 16. Return pressure is applied to armature 81 by wire spring 88. The magnet assembly 86 is attached to the molded part of the brush carriage by screw |81.

As the thread 84 of the worm shaft 81 is continuous, shoe 83 is caused to make a 90 turn in opposite directions ,each time the brush carriage reverses its direction of motion. To shoe 83 is attached shaft 89, Fig. 9. To the bottom of this shaft, which passes through a hole |88 molded in frame 18, is attached segment 90, Fig. 13, of a spur gear which engages rack 8| molded in -the brush shift member 23. In the relative position shown, it is assumed that the brushes are over the row of terminals as shown in Fig. 8. Thus, on the return journey, shaft 88 would rotate 90 and shift the brushes over to the adjacent row of terminals. Whenthe otherend of the selector is reached, the brushes are shifted back, and s'o on. In this way, a 120 point selector is obtained from a selector having duplicate rows of 60 'terminals each. Brush shift member 23 slides on T runway |09, Fig. 9, forming part of 88.

In non-shift selectors where eight to ten brushes are available, brush shift member 23 is fixed in position. With the particular feeder block arrangement shown in Fig. 8, eight brushes can be served. In a five-brush selector, ten brushes would be used.

In Figs. 14 to 18 is shown an alternative ar-q rangement in which latilting rod I 3 is used in place of the magnet 8B. The rod is tilted in Figs. 14, l5, 17, 18 and normal in Fig. 16. It is caused to tilt strip 99, Fig. 14, upward when armature 61 of the main clutch magnet 1 is attracted. Inclined surface part 82 pressed out of armature 51 engages roller 93 and forces it up to the position shown from its normal position indicated 18, 8l, and 8U are by dotted lines 94 (Fig. 17) against the tension of a strong retractile spring 95 secured at one end to flange 96 welded or otherwise attachedtto rod I3 and at the other end to vlug 91 forming part of Ithe clutch frame or its equivalent. Roller 93 is suitably attached to part 96. As the tilted shaft is under considerable tension, it is suitably held in position in the selector frame I by selfoiling bearings 98, one at each end. These bearings .are placed in a continuation of the slot under home contact rods 'I'2.

Inside the selector and running the full length of the travel of the brush carriage is part 99 welded or otherwise attached to shaft I3. When shaft I 3-is tilted upwards, this part 99 moves upwards and removes pressure from lug |00, thus allowing plunger arm IOI, of which lug forms part and to which is attached brush plunger 25, to move upward under tension of spring |02. The upward motion of plunger arm IOI is stopped by projections |28 striking against the underside of the adjacent part of brush carriage 18. The downward motion of the plunger arm is stopped by similar projections |29 which strike the upper surface of the brush carriage when the plunger arm is forced into the operating position, Fig. 16.

l When armature 61 is released, it vfalls back Y principally under the tension of spring95, but

over each selector. The pointers ||9 are exposed 'Iliie free position of plunger arm |0| is shown on one side of thenumber strip or on the other from one side to the other, pointer arm |20'turns,

about screw pivot I2I and buries one of its two indicating points ||9 and exposes the other. By -burying the pointer, is meant slipping' it under the opaque number strip.l

The home contact spring assembly IIOFigs. 1 and 2, is molded into a small separate unit 4 which is forced into holes |36 molded in frame as shown in'Figs. 5, 6, and 19. If a selector always makes its home positionl at the home spring contact end, for example, the right hand end, Fig. 2, a vsimple insulated part attached to a home contact spring or to the brush carriage will sufilce to open and close the home contacts as conditions require when the selector is in its home position. However, since the -system in which the selector is to be used may require the home position to be in different locations on the selector, a rocker rod I2 is provided for. This away from the springs |I0 under the tension of the springs themselves or under the tension of a separate spring, according to which plan is found to be the best. To turn rod I2, adjustable part II'4, Fig. 8, is shifted along the rod to the proper position and there secured by set screw II5 or its equivalent. The lower lip of ||4 is placed 45 one way or the other off the axis of shaft I2; thus when pin |I6 attached to the traveling brush carriage contacts part I I4, it will force it and consequently rock rod I2 one way or the other depending lupon which side of the slanting lip of ||4 it hits, the idea being that the home contact rocker arm plunger |'I3 moves into contact with home contact. springs |I0 only when the brush carriage is traveling in the proper direction.

The brush carriage makes a complete cycle go and return in two seconds. The hunting speed is approximately 62 to 64 terminals per second.

With 6 lthreads per'length, the molded worm makes six revolutions'per second or 360 R. P. M.

ket I6, Fig. 2, which gasket also tends to hold down tightly and uniformly the variousmolded plugs 59, 60, and 6| which hold the shafting in position. The transparent cover I5 is held in position by eight screws 6 and is sealed at As sides I4 will not be removed after the selector is in position on a bay, sealing compound may be used to seal the joint; between the sides land the grooves should this' additional precaution be found advisable or necessary.

The design of the tri-selector foresees ease of assembly, dismounting 'and re-assembly.y All parts have been designed so that they may be preadjusted and gauged so as to make further adjustment unnecessary when the parts are 'assembled. There will be some nal adjustment when partial assemblies are-made, for example, when the brush springs are attached to the brush carriage or when the home contact springs are removed from the mold. These partial assemblies are given their final adjustment before the nal assembly in the frame-is made. vTo assemble a tri-selector, no internal wiring or soldering of connections is involved. The order of assembly is about as follows: First, the home contact assemblies 4 are forced in the holes |36 into position in the frame I.- Next, the main bearing shaft II is slipped through the two bearings 'I9 of the brush carriage frame I8 and with the two

feeder blocks

35, 36, the four parts are slippedintor position, the molded grooves |35, |30 in the frame I accurately positioning the bearing shaft II and the feeder blocks 35, 36. 'The feeder blocks are secured in position by the screws 8 and clamps 38 provided for the purpose. These screws 8 assure ample pressure between the feeder strips 32, 39 and the jack springs -3 in the frame I. The home contact rod I2th`e moldee shaft 58, and the tiltingrod I3, if one is used, are now slipped into position after which the molded plugs 59, 3,, 6| are forced into their respective grooves lin the upright ends of the frame I. Prior to nal assembly, the rocker arm II2 and rocking device ||4 on the rocker shaft I2 are properly adjusted with respect to each other. 'I'he two sheet iron sheets I4 are slipped into position, after which the transparent cover with gasket I6 is screwed into position and sealed. The clutches are now mounted in position and the selector is ready for check testing.

It will be noted that the molded driving cone slips into position. It is held on the shaft in its normal position by pressure of armature 6l of the clutch and lts operating position by the driving surface of disc 63. The driving disc is made considerably wider than the driving surface of the driven cone. 'Ihis is done to provide means for a reasonable adjustment of the air gap by moving the driving disc up or down on the vertical shaft.

It is not expected that a tri-selector properly built will have to be opened for any purpose whatsoever except at infrequent periods of five or tien years. To open a tri-selector, the two seals are cut, after which the transparent cover |5 may be removed. Each selector may now be lifted out separately, first withdrawing the plugs 58, 60, 6| holding down the shafts and then the screws 8 holding the feeder blocks 35, 36. All parts may now be removed without the unsoldering of any connection. The individual parts may be gauged, checked, readjusted, reconditioned, or replaced as required and the whole then reassembled as previously required. The bearings are of phosphor bronze impregnated in oil and thus'l self-lubricating. They should require little treatment over a long period of years.

With the aid of a bright and shaded lamp it is possible to make a careful examination of the movement of selectors from the' outside looking through the transparent cover 5. Any undue wear or cutting will be indicatedby accumulations of particles of metal or plastic dust. When -this is noticed, the selector should be dismantled .the tri-selector is on the bench. The free end of one pattern will project over for welding to the corresponding terminals of the adjacent triselector when the tri-selectors are mounted on the supporting strip which forms part of the bay framework.

Each of lthe three selectors in a tri-selector has, of course, a complete set of bank terminals for hunting over. However, only one-third of the terminals of each selector are brought out beyond the ribbon cable at the rear of the fiber strip protection |24. Two-thirds o'f the terminals terminate at the end of the ribbon cable weld |22; the other one-third project beyond fiber protection strip |24. These projections |25 are available for soldering to the outside cables. One of the selectors in a tri-selector would have terminal rows 1, 4, 7, etc. brought out, another would have terminal rows 2, 5, 8, etc. bought out, and the third

selector terminal rows

36, 9, etc. The

rear of each tri-selector thus affords ample space without crowding for outside cable soldering and as each tri-selector is its own terminal strip, separate terminal strips are thusl made largely unnecessary.

In order to facilitate welding, it is proposed to mount selectors when ready for cabling on accurately drilled fiat metal strips |26, Fig. 2. These flat strips allow easy access to the terminals when welding. After Welding, the rest of the lbay framework, for example, the sheet metal sides |21, is fastened in position.

Although certain embodiments of the invention have been shown and described for the purpose of illustration, modifications occurring to those skilled in the art may be made without departing from the scope of the invention as defined in the appended claims.

It is also to be understood that in place of silver contacts where specified in the preceding rescription, contacts of other precious metals or their alloys may be employed.

What I claim is:

l. A selector switch of the kind used in telecommunication systems and the like comprising bank terminals, a flat panel in which said terminals are mounted, a plurality of brushes, a movable carriage for said brushes, a rotatable shaft for moving said brush carriage over said bank terminals, bearings for each end of said shaft, two end frame members, slots in said end frame members formed with seatings for said bearings,` and plugs slidable in said slots for retaining saidbearings on said seatings.

2. A selector switch according to claim 1 further comprising off-normal contacts and a rocking shaft for actuating said off-normal contacts journalled in said two end frame members.

3. A selector switch according to claim 1 further comprising a tilting bar for moving said brushes into rubbing engagement with said terminals the ends of said tilting bar being journalled in said end frame members.

4. A selector switch of the kind used in telecommunication systems and the like comprising bank terminals, a plurality of brushes, at least one rotatable shaft for moving said brushes over said bank terminals, a molded frame member including a fiat base in which said bank terminals are molded and two upright end pieces, bearings for each end of said shaft, molded slots in said end pieces formed with seatings for said bearings, and plugs accommodated in said slots for holding said bearings on said seatings.

5. A selector switch according to claim 4 wherein said bearings are of the oil-impregnated selfaligning type.

6. A selector switch according to claim 4 further comprising two side members, a cover member, grooves in said base and said end pieces for accommodating the edges of said two side members, means for securing said cover member to the said end pieces, and gaskets interposed between said cover member and said end pieces for providing a dust proof joint and for holding said plugs in position in said slots. i

7. A selector switch according to claim 4, further comprising a power shaft adapted to be driven by a source of power, an electromagnetv in said slots for said feeder blocks and meansfor secur ends of said blocks in said grooves. .t

- associa s tire 9. A selector switch of the kind usedin tele-4 i communication systems and the likecomprising bank terminals, a plurality-of brushes, a brush carriage, at least one bearing shaft for said brush carriage, a rotatable shaft for moving said brush carriage along said bearing shaft, a molded frame member including a nat base'in .whichfs'aid'terminals are molded and two upright endpieces, bearings at the ends of said rotatable shaft,;slots terial, a'cover member, grooves in said.; basefand said end pieces for accommodating theedgesrof rarity4 olf-rotatable shafts 'for moving said brush sets over said sets of bankterminals,` a unitary molded frame-member including'af at base in 'which said sets oi bank terminals -are molded so as to projectfrom the rear of said base, two upright end pieces in which the ends of .said shafts are journalled, and ribbon cables .for multiplying together -saidn sets of.v bank terminals,the projecting endsof l/n of said terminals'extending beyond'the ends of the remainder to provide term'inals for effecting-electrical connection to outside cables.: f i t 14. A selector switch assembly according -to claim 13 further comprising a;separator ,strip of insulating material mounted between saidiribbon cables and the extended ends of said terminals .I

#provided fora-connection to outside cables.

saidtwo side membersy'meansl for securing; said cover memberv to said -end'piecea and i gaskets finterposed between said cover member and saidrend pieces' forlproviding a dustfprcof joint land for holding said plugs in position :in said slots. f

11. AA selector switch 4 assemblylo'rusefin telecommunication systems and the'like 'comprising atleast two-sets ofbank terminals, at least 'two sets'of brushes, a plurality of rotatable shafts lfor moving-saidbrushrsets over, said sets ofbank terminals, and a unitarymolded frame member including a at base fin which saidsets ofbank terminals are molded and twoupright *end pieces in which the ends'of said shafts are journalled.

12.- A selector 'switch assembly according to claimv 11 further comprising bearings for said shafts ofthe oil-impregnated self-aligning. type, molded slots in said end pieces formed .with .seatingsfor saidbearings, and plugs accommodated seatings.

Y 13. A. se1 "tor switch assemmy for use'iri tela,

communication systems and the like-comprising holding said bearing's on said 15.;ili..fla tA unitary terminal bank for a group of .njselecton 'switches comprising n sets of bank terminals; formed ,of metal. strips molded into a dat-molded basemember so as'zto project from the rear .surface thereof, ribbon cables extending acrossthe bank adjacent its rear surface for multipling together said n sets of lbank terminals,

wherein ,rows of terminals disposed at regular intervals in each set of bank terminals extend beyond the remainder and wherein the positions of said extended terminals are staggered in adjacent sets of terminals so as to regularly distribute said extended terminals over the entire rear surface of said bank.

, GERALD DEAKIN.V