US2335110A - Electrical switch - Google Patents

Description

NW. 23,1943. c. WfDANN 2,335,110

ELECTRICAL SWITCH Filed June 11, 1941 2 Sheets-Sheet 2 INVENTORV Char/es W Dan/1 TTORNEY Patented Nov. 23,

UNITED STATES PATENT orncs Claims.

This invention relates toelectrical switches and more particularly to improvements in the construction and operation of such switches.

My invention has especial relation to and is herein illustrated and described in connection a with multiple-point multiple-throw snap switches, but it will be understood that no unnecessary limitation of my invention to this type of switch is intended as many of the features of my invention may be advantageously em- 10 ployed in other types of switches.

Multiple-throw snap switches have a wide field of application. They are, for instance, employed -in high voltage power circuits as well as in low level audio circuits such as in oscillation amplil5 tiers and other communication devices. In some instances of these applications, it is highly important that the switches be well insulated and well shielded against shock to the operator, and

that they have a fast action to avoid undue arcing at their contact points; in other instances, it is of prime importance that the switches make a reliable positive contact at their points without bouncing, and that they have a low capacity between their circuit elements and still be small in overall size. It is an object of my invention to provide a switch which is particularly well suited to these widely different applications.

It is another object to provide a switch in a completely shielded form which is easy to adjust and wherein th parts are readily removable for replacement or repair.

Other objects are to provide a compact construction of a switch which is adapted for easy mounting and wherein the parts are cheap to manufacture and easy to assemble.

Multiple-point multiple-throw snap switches are of a kind wherein a progressive actuation of the switch mechanism will cause the movable contact member of the switch to be moved with a snap action through intervals into successive switch positions. In this kind of switch, the latch for catching the movable switch contact member in its respective positions must be carefully designed or else it may fail to operate and cause the movable switch contact member to overshoot the position at which it is to be stopped. In the present invention this possible misoperation of the switch is prevented by the provision of a latch of an improved construction for the switch.

It is accordingly an object of my invention to provide an improved latch for a multiple-throw snap switch which is positiveand dependable in its action and well-nigh foolproof against misoperation.

Another object of my invention lies in the pro-.

vision of an improved construction and arrangement of a snap mechanism for a multiple-throw switch wherein the latch members are moved into latching relationship during the travel of the movable switch contact member from one switch position to the next.

It is another object to provide a latch arrangement the release of which at one switch posithe next succeeding switch position.

Another object is to provide a latch arrangeinvention lie in the combinations of elements and arrangements of parts herein disclosed and will be apparent from the following description and the appended claims.

" In the description of my invention reference is had to the accompanying drawings, of which:

Figure 1 is a view in elevation of a three-position (1. e., double-throw) snap switch constructed in accordance with one embodiment of my inven-- tion, a portion of the front half of the housin being however broken away for the better i1lus-' tration of the interior parts of the switch, and the switch parts being shown in the positions which they occupy when the switch is in its intermediate position;

Figure 2 is a view similar to Figure lbut showing the switch parts in the relationship which they have to one another when the switch 'is in the top portion of the switch substantially on the ,line 3-4 of Figure 6;

Figure 5 is another horizontal section taken substantially on the line 5-"! of Figure 2;

Figure 6 is a fragmentary view similar to Figure 2, showing the switch mechanism in a partially actuated condition;

on the line 1-1 of Figure 1; I

Figure 8 is a vertical sectional view taken on the line 8-4 of Figure 2;

Figure 9 is an internal view of the lower portion of one of the sections of the housing;

tion automatically renders the same effective at one of its terminal positions, the front half sechowever through the lower portion of the switch Figure '1 is a top horizontal sectional view taken Figure is a fragmentary sectional view illustrating the mode of adjusting the contact springs of the switch;

Figure 11 is a sectional view taken substantially on the line IIII of Figure 10;

Figure 12 is a vertical view of a second embodiment of my invention, the front housing section of the embodiment being removed and parts thereof being in section substantially on the line I2--I2 of Figure 14;

Figure 13 is a vertical sectional view taken substantially on the line I3-I3 of Figure 12;

Figure 14 is a horizontal sectional view taken substantially on the line I|-I4 of Figure 12; and

Figure 15 is an exploded view of a switch stack assembly as in accordance with the present invention.

Reference being had to'Figures 1 through 11 there will be seen an embodiment of my invention havinga frame or housing comprising two identical sections I. These sections are substantially iii he form of rectangular shells made for example of a suitable material such as zinc and for'rne'd as by die casting. The sections are aligned with one another by means of dowel pins I' inone of the sections which engage holes I" in the other of the sections. When the sections are assembled they form a housing which is open at the bottom and provided with a threaded tubular neck 2 at the top. The neck 2 is employed as a means to hold the housing sections together at the top, it being made up of two semicircular' portions 2 which are integrally formed on the respective housing sections" and held together by a nut 3. The neck also serves as a means for mounting. the switch on an apertured support or panel 4 shown in Figure 2, it being extended through the support and secured thereto by a nut 5 threaded on the outer portion of the neck. (As is hereinafter explained, this neck also provides the opening in the housing through which the switch-operating lever projects.) The housing sections, are clamped together at the bottom by a bolt 8 and nut I as is shown in Figure 5. This bolt passes through interior apertured bosses 8 in the housing sections, which serve to guide the bolt through the housing sections in the assembling of the switch. The head 6' of the bolt,

and the nut 'I, are each received in recesses 8 so In the lower part of the housing there are provided two switch stack assemblies III which are respectively mounted on opposite sides of the clamping bolt 6. These stack assemblies each comprise two sets of switch contact members arranged to effect a double-pole double-throw switch action, there being two centrally located switch pole members I Ithe movable switch contact members hereinbefore referred to--and two pairs of outer semi-stationary switch contact members I2 which are held in line with the central pole members II respectively. These switch members II and I2 are held in cantilever fashion between insulating blocks as in the manner illustrated in Figure 15. The outer ones of these insulating blocks are identical in shape and are each referred to as I3; these blocks have recesses I4 in their inner i'aces which extend through the blocks from top to bottom. At the center of the recesses, however, there are provided bosses I5. The semi-stationary contact members I2 fit these recesses at opposite sides of the bosses I5 and are provided with arcuate notches I6 which are engaged by the sides of the bosses; this engagement serves to hold the switch members from longitudinal displacement in relation to the stacks. For purposes of standardization of parts, to permit the contact members I2 to be used interchangeably at the sides of the switch stack assembly, the contact members may be provided with a notch IS in each edge thereof, as is shown in Figures 8 and 15. Between the central and outer switch contact members I I and I2 there are provided two insulating blocks I1 and II. The faces of these intermediate blocks which are adjacent to the outer blocks I3 are identical in shape and formed to fit the recesses I4, the faces each having central holes I9 to receive the bosses I5 when the blocks are clamped together (see Figures 5 and 15). The two intermediate blocks I1 and I8 fit one another at their adjacent faces in the same way as that in which they fit the outer blocks I3. For instance, the intermediate block I1 is provided with a recess I4 and central boss I5 and the other block I8 is centrally apertured to receive the boss and shaped to fit the recess, the block IB thus having its aforementioned central hole I9 extending therethrough and having its opposite faces similar in shape. Between the intermediate blocks are clamped the pair of switch pole members II, they being disposed in the recess ll of the block II at opposite sides of the boss I5 01' this block and also provided with notches I6 to engage this boss as for the reason above explained. These blocks may be conveniently formed by molding and may be made of any suitably moldable insulating material.

The switch stack assembly above described is clamped together by means of two end plates 20 and 2| and abolt 22 which passes centrally through one of the plates and threads into the other. The bolt 22 passes centrally through the insulating blocks by way of apertures 23 in the bosses I5, and the end plates are received in depressions 24 provided in the outer faces of the insulating blocks I3 to locate the plates accurately in the switch stacks.

In the switch stack assembly here described, each switch contact member is embraced by the cooperating insulating blocks and is firmly held in place against both lateral and longitudinal displacements. Moreover, each is fully insulated from the clamping bolt 22 through the medium of the bosses I5 of the insulating blocks. Since these insulating bosses are integrally provided on the insulating blocks, the number of parts of the stack assembly is reduced; further, the provision of a clamping means wherein the clamping bolt is not passed through the switch members, permlts the switch members to be made quite narrow. This reduction in parts and avoidance of the necessity for threading the switch contact members on the clamping bolt greatly simplifies the assembling of the stack.

The switch contact members II and I2 are in the form of flat springs which are made of any suitably conductive and resilient material. In the case of the switch pole members II, these springs serve merely as hinges since the members are each held rigid along their free lengths by a pair of bars 30 which are secured to the springs through rivets III. The upper end portions 32 the stack assembly against the inner sides oi. the

outer switch contact members, and like the switch contact members II and I2, are provided with notches "3 which engage the bosses I! of the insulating blocks to hold the stop members from longitudinal displacement. The semi-stationary engage the sides of the contact members are biased inwardly against 2 the respective stop members and the latter are made of a dead-soft (i. ei, ductile) material so as to be capable of being readily bent into desired positions. For instance, in Figure l and 2 the stop member 33a on the left has been bent in wardly sufiicientlyto allow the contact point |2'a to make contact with the opposing member not only in the left but also'inthe central switch position.

In the sides of the housing sections, at the place where the outer or semi-stationary contact members I2 and respective stop members 33 emerge from the switch stacks, there are provided circular openings 31. These openings are adapted to receive a tool for adjusting the con-,

lugs 33, and the switch pole members H are provided with separate lugs 34 which are clamped in the stacks against'these membersall 0! these lugs projecting below the stacks a shown. The lugs 34 are also held against longitudinal displacement by notches l6 provided therein which bosses l5 of the insulating blocks. i r

The switch stacks (the stack assemblies ll hereinbefore described) are removably mounted in the lower portion of the switch housing in positions at the sides oi'the interior bosses 3. 'The end plate 20 has extensions 20 beyond the sides of the stacks, butthe other end plate 2| is substantially' flush with these sides, as is shown in Figure 5. In" the interior walls of the housing sections are grooves 35 into'which the plate ex-- tensions 20' fit and atthesides oithe bosses 3 are shoulders 36' against which the ends oi the plates 2| abut. These grooves 36 and shoulders 36 run downthrough the bottom of the switch housing'to permit the stacks to be slid into and out of the housing. To retain the stacks in the housing, the plates 2| are providedwithlproiections 2| and the shoulders 36 with notches 36" to fit. these projections (see Figures 3 and 9).

The width of theplates 2| is such that when the housing sections are clamped together the shoulders 36 will bear againstthe ends of these plates and firmly hold the stacks in place. The engagement oi the extensions 2|! of the plates 20 with the grooves serves to effect a straight aligntact members I! and to guide this tool into engagement with these members. A suitable adjusting tool for this purpose, which is shown in Figure 10 as 38, has an end portion 33' provided with an open slot 39 so that it may engage the respective pairs of contact members I2 andstop' members 33 of the stack; also, the. tool has a shoulder 33" near the end thereof which is adapted to abut against the switch housing as the. tool is inserted in the openings 31, 'to'limitthe distanceof insertion of the tool.' Thus, to ad-. just the spacing between any-particular. set of contact points, or to set a ston member 33 so that its contact member I! will make contact also in the'central switch position, the tool is inserted intothe-desired one of the openings 31, is turned until the slot 39 is aligned with the pair of con tact and stop members adjacent .to;that one opening and'is then further inserted into the opening until the shoulder 33" abuts against the switch housing, after which the tool is suitably turned to effect the desired adjustment. To permit observation of the contact points during such adjustment, there are providedwindows 40 in the housing-sections at the points as shown in Figures 1- and 2. A the stop member 33 and contact member- I! 'are' bent-in-this way. the contact member -|2 will be placed into a new position determined by the amount of permanent set. given to the stop member, Since the stop members are made'of a ductile material, and the contact members aremade of a spring material whose elastic limit is not-exceeded by the bending operation, the new position of the contact member may be very accurately determined. Also. the contactpressure, which is determined by the degree of loading or biasing of the switch member l2 against its stop, will remain substantially unchanged.

In order that soldering will not have to be done to the springs of the contact members H and i2, to make the lead connections to the switch, the stop members 33 are provided with ment of-the switch stacks within the housing. As so arranged,.thestacks are held firmly in place but are readily rendered removablemerely by loosening the clamping bolt 6 and spreading the housing sections slightly apart. 4 I

The operating means for the switch comprises an operatingbr control lever 46 and'a snap mechanism 42. The lever 46 extendsthrough the neck 2'0! the housing and has a pin 41 secured thereto which is pivoted at its ends in recesses 2" provided in the neck'portions 2' (see Figure 3). The snap mechanism," isof a unitary construction and is movably mounted in the top portion of thehousing, the mechanism having a bottomplate' 4| of rectangular shape which slides at its sides in-grooved members 43'integrally formed on the housing sections. Secured to the bottom of the plate 4| by rivets'45 is a bracket-shaped member 44 having two downwardly extending lugs 44', this member being.

formed as by molding, from a suitable insulating material. The lugs 44 of this member pivotally engage the ockets 32' of the switch pole members I to couple the snap mechanism thereto. In the actuation'of the snap mechanism, the plate 4| is moved along the grooved members 43 trans- .versely oi the housing and this movement is transmitted to the switchjpole members II to operate the switch into its respective positions.

The snap mechanism "comprisesa bracket 48 which is secured to the'top of he plate 4| by the aforementioned rivets 45, the bracket being considerably narrowerthan the plate and having laterally extending lugs 49' at its central portion through which the rivets 45 pass (see Figures 4 and 6). The legs 48' of the bracket extend up from the plate 4| and are bridged at the top by a yoke 50 which has a slot 5| lengthwise thereof. Between the yoke and the bracket there are two pins 52 the-outer portions of which extend slidably through apertures 53 in the legs 48' of the bracket 48. On the inner end of these pins are heads 54 which slide between the yoke and bracket. The top and bottom portions 54' of these heads are reduced in width to fit the slot II in the yoke at'the top and to fit a slot 48" in the bracket 48 at the bottom, the engagement of the heads with these slots serving to hold the heads against lateral displacement. The lower end portion of the lever 48 extends down through the slot ilin the yoke and carries a roller 55 at its end which is held between the heads 54. Coiled about the pins between the heads thereof and the legs 40' of the bracket 48 are compression springs 58 which press the heads of the pins against the opposite edges of a stop member in the form of an I-shaped plate 51 which is clamped against the central portion of the bracket 48 by the rivets 45 aforementioned. The width of this plate 51, at the place where the heads abut thereagainst, is made substantially equal to the diameter of the roller 55 in order that the roller may be normally held between the heads without play. By this construction the spring pressed pins 52 serve to yieldably couple the control lever 46 to the snap mechanism 42 and to normally confine the lever to a neutral (i. e., central) position in relation to the snap mechanism. While the lever and snap mechanism may be displaced in either direction out of this neutral position, it will be seen that this can occur only through a compression of one or the other of the springs 58.

The snap mechanism is normally held latched to the switch housing but is released by a predetermined displacement oi the lever 46 out of its neutral position just mentioned, the particular one of the springs 58 which is compressed by such displacement of the lever serving as the motive means to propel the snap mechanism with an impulse when the mechanism is released. The propelling of this mechanism with a snap movement renders it particularly difficult to provide the mechanism with a positively acting latch. In th present instance, however, this dimculty has been effectively overcome by means of a latch arrangement which comprises a pair of unidirectionally or one-way acting latches, one foreach direction of movement of the switch pole members, which latches are then'respectively directed in the several directions of movement of these pole members. In such a latch arrangement, it will be seen that the cooperating latch members are permitted to move into engagement with one another during the travel of the movable switch members from one switch position to the next and that, as a result, a positive and dependable latch action is obtained.

The latches of the snap mechanism in the present embodiment comprise two similar U-shaped pawls 60 which overlie the plate 4| and straddle the opposite end portions of the bracket 48. These pawls pivot at their inner ends on the side edges of the lugs 49 of the bracket 48, the pawls being retained in such pivotal contact with the lugs by the cross extensions of the I-shaped plate 51 which overhang the sides of these lugs. The pawls are torsionally biased upwardly by means of tension springs 6| which are connected between upstanding lugs 62 provided at the sides of the pawls near their inner ends. The outer ends of the pawls have abutment faces 80, which in order to reduce wear, are made as wide as possible by lateral extensions 63. Thesefaces engage the teeth 64 of catch members 65 provided in the top four corners of the housing and formed integrally with the housing sections (Figures 2, 4, 6 and 8). These teeth are ratchetshaped and the pawls are inclined thereto to assauo form a pair of one-way acting latches; however, the two pairs 0! catch members at the opposite ends of the housing have their teeth oppositely directed, as shown in Figures 2 and 6, in order that the latches will, in their Joint action, be eflective in both directions of travel of the snap mechanism.

The pawls are selectively disengaged from the catch members by the lever 48 through the medium oi the pins 52. This disengagement occurs through a displacement of the lever out of its neutral position abovementioned, the particular pawl which is disengaged depending upon the di rection of this displacement. For instance, when the lever 46 is swung to the left, as is illustrated in Figure 6, the rightward one of the pins 52 is moved to the right and in relation to the plate 4|. When this pin .has been so displaced a predetermined distance, the outer end thereof impinges against the top central portion of the rightward one of the pawls ill and cams this pawl downwardly out of engagement with its respective catch members, whereupon the plate 4| is propelled to the right. As the plate or snap mechanism is so propelled the pin 52 is retracted from the pawl just released to permit the latter to return, under the influence of the springs 6|, back into engagement with its associated catch members. In the movement of the snap mechanism from central to terminal switch positions, this reengagement with the catch members of the pawl last released is, in the present structure, of no importance as the snap mechanism is stopped at its terminal positions by the abutment of the pawls or plate 4| against the ends of the housing (and since the snap mechanism is stopped in its terminal positions in this manner the catch members need each have only one complete tooth or two abutments as shown) however, in the movement of the snap mechanism from terminal to central positions, the reengagement with the catch members of the pawl last released is relied upon to stop the mechanism. This reengagement is, however, insured in the present structure as the ratchet shape of the teeth of the catch members permit the released pawl to move back into engagement with the respective catch members while the snap mechanism is moving to central position. As the mechanism completes an interval of travel the trailing pawl engages one or the other of thetwo abutments abovementioned to latch the mechanism against return movement.

Since the snap mechanism 42 and the stack assemblies [0 are provided as self-contained units, the assembly of the switch is very simply carried out. For instance, to assemble the switch, the lever 46 and the mechanism 42 are laid in place in one of the housing sections-the pivot 41 of the lever being inserted in the recess 2' of the housing neck portion 2' and the mechanism 42 being laid with its plate 4| in engagement with the grooved member 43and the other housing section is put in place and secured to the first section by the collar 3 and the clamping bolt 6, the latter being however not tightened; the switch stack assemblies are now inserted into the bottom of the housing with the projecting edges of the plates 20 being brought into engagement with the grooves 35, and then the stack assemblies are pushed inwardly until the sockets 32' come into engagement with the legs of the bracket 44 and the projections 2| with the notches 35'. The tightening of the clamping bolt 6 completes the assembly operation.

In Figures 12, 13 and 14 there is shown a sec and engage apertures sulating plate. On these bar members 30a there 2,sss,11o

ond embodiment of my invention which differs from the embodiment above described, principally in the arrangement of its switch-operating mechanism. (In the showing of this second embodiment, those parts which are identical with the corresponding parts of my first embodiment are given the same reference characters and several parts which are slightly modified are given like reference characters with the addition of the letter a, while other new parts are given new reference characters.) This second embodiment comprises two identical housing sections la, differing from the sections I only in the shape of their interior walls. The housing sections are clamped together at the bottom in the same way as before, and have the neck portions 2' embraced by the collar 3 to hold the sections together at the top. In the lower part of the housing there are provided the switch stack assemblies II), the same being removably mounted in the manner hereinbefore described. An adjustment of the spacing between adjacent contact points is made by the tool 38 in the manner hereinbefore described, and inspection of the contact points is again had through windows 40 provided in the housing sections.

The snap mechanism of this embodiment includes a plate of rectangular shape which is slidably mounted at its sides in grooved wall portions 'Il integrally formed with the housing sections. This plate is insulatedly coupled with the switch pole members ll through the medium of a plate 18 of insulating material, which is slidably mounted below the plate III, in grooved wall portions 18 also integrally formed with the housing sections. These two plates are intercoupled by means of lugs 10' turned down from the sides of the plate Ill into engagement with notches II proyided in the plate ll, and the plate I8 is coupled to the switch pole members H by means of straight bars 30a. These bars are secured to the pole members by the rivets 3! (not shown) 18". provided in the inare provided contact points II' for the switch pole members. Thus, the plate Hi is mounted to slide back and forth transversely of the housing and, as the plate is so moved, the switch pole members II are swung back and forth into and out of contact with the semi-stationary contact members I! of the switch stack assemblies l0.

The plate 10 of the snap mechanism has a central opening 12 which is bridged centrally thereof, in the direction lengthwise of the plate, by a rod 13 which is staked at its ends to the plate, as is shown in Figure 14. Slidably mounted on the rod are sleeves ll which are respectively confined to the end portions of the rod by a central enlarged-diameter portion 13 of the rod. The sleeves II have flanges 14 at their inner ends, and are pressed inwardly against the shouldered ends of the central portion 13 of the rod by means or compression springs 15 which are coiled about the rod and sleeves between the flanges and the portions of the plate at the ends of the rod. A manual control lever 16 for the switch is pivoted as at I! to the neck 2 of the housing. This lever has two diverging arms 16" at its inner end which straddle the rod 13 and clear the flanges I4. On these arms are inwardly extending cylindrical projections 11 which terminate between the flanges 14'. Thus through the spring-pressed sleeves 14 the lever 16 is yieldably coupled to the plate II and is normally held in a neutral or central position in relation thereto. a

The plate 10 is adapted to be latched incentral and terminal positions by means of two identhe housing sections and are biased upwardly by means of torsional springs 83 which are coiled about the rods 8|, hooked at one of their ends on the pawls and restrained at their other ends by the housing. The pawls are arranged to pass up through the opening I2 of the plate 10 and to abut at their end portions, against inward extensions 84 of the plate at the diagonally opposite corners of the opening 12, the pawls and the plate extensions I4 in this way forming a pair of oppositely directed latches each of the one-way acting type. Asbefore, an abutment of the plate 10 against the housing ends is utilized to define the terminal positions of the plate; accordingly. each of the latches need have only two latching positions. To render the pawls effective at such two positions, each is provided with two abutting faces at its inner end portion, a face 85 constituting the vertical edge of a step 85 provided on the pawl and a shoulder 85 positioned above and in from the face 85 and constituting the vertical edge of a ste 86'.

These pawls are operated through three positions. the intermediate and uppermost positions constituting the two effective or latching posi tions of the pawls. For instance, the latching 'of the plate 10 in the rightward one of its terleftward one of its terminal positions is effected when the rightward one of the pawls is in uppermost position by the abutment of its end face 85 against the respective one of the plate extensions 8|. Whichever one of the two pawls is not in use in the latching of theplate in a terminal position, is held in its lowermost position by the abutment of the step 86' of the pawl against the bottom of the respective extension 84 of the plate. The latching of the plate 10 in central position requires the use of both pawls at the same time, and is effected when both pawls are in their intermediate positions by the abutments of their shoulders It against the ends of the respective extensions 84 of the plate.

The pawls are appropriately controlled by the manual lever 18 through a camming of the two arms 18" of the lever with respective cam faces 88 provided on the pawls. These faces extend along the central portions of the pawls and are so curved that when the upper end of lever 16 is to the left, the left pawl is in its uppermost position and the right pawl in its lowermost position; that when the lever is in central posi tion, both pawls are held in their intermediate positions; and that whenthe lever is to the right, the left pawl is in its lowermost position and the right pawl in its uppermost position (see Figure 12).

The operation of the switch mechanism of this second embodiment is as follows: When the lever 16 is moved to the left from its right terminal position the plate 10 is placed under a rightward bias by the displacement of the right one or the spring-pressed sleeves H, and the right pawl, which now latches the plate in its left terminal position, is cammed downwardly to disengage the end face 85 thereof from the plate, the left pawl being freed from the lever for upward movement but restrained momentarily by the plate. When this disengagement of the right pawl occurs. the plate is propelled to the right, to break the circuit between the left set of semi-stationary contact members I2 and the switch pole members II. The plate is however, stopped positively at its central position by its abutment against the shoulder 8 of the right pawl, and is automatically latched against return movement when it reaches this position by the-left pawl which is snapped upwardly into intermediate position as the plate slides off the step 86 of this pawl. Upon a further leftward movement of the lever 16, this action repeats itself; the plate being again placed under a rightward bias, the right pawl being cammed down into its, lowermost position to unlatch the plate, the plate being then propelled into its right terminal position, and the left pawl then snapping upwardly into its uppermost position (as the plate slides of! the step 85) to"latch. the"plate against return movement. Upon moving the lever 16 to the right, the sequence of operations .here related will, of course, be reversed.

The mode, .of operation of the latches of this second embodiment is one causing the switch to be latched in its several positions in succession as the pawls are moved progressively through their successive latching positions (1. e., as the pawls and respective plate extensions 84 are progressively engaged), and the release of each pawl from one latching position automatically renders the same effective as to its next latching position, In other words. the switch is unlatched by one pawl for movement in only one direction at a time and then only for a distance from one position to the next; and when the switch has reached this next position, the other pawl snaps into place to latch the switch against return movement. This mode of action of the latches will be seen to be wholly positive and dependable.

As a summary of certain salient features or my invention, it will be noted that the switch embodiments herein disclosed are of a durable construction and dependable operation; that the switches are completely housed to protect the parts thereof from dirt, to guard against shock and to electrostatically shield the switch circuits; that while the switch is completely housed, yet it may be readily adjusted and serviced or repaired; that while the construction thereof is compact, yet the switch circuits are relatively widely spaced to reduce the electrostatic capacity therebetween; that the locating of the semi-stationary spring contact members by biasing the same against adjustable stops serves to provide deflnite yieldable contact pressure between the conmany other changes and modifications without departure from the scope of my invention, which I undertake to express according to the following claims.

I claim:

1. A mechanism for latching a switching member of a multiple-throw switch in its several positions respectively, comprising a frame, a pair of one-way acting latches operatively interposed between said switching member and frame and respectively effective on said switching member in the opposite directions of movement thereof, each of said latches including two cooperating and relatively movable members and one of the members of each of said latches having a portion provided with a plurality of successive steps adapted for selective engagement with the other or said members, the release of one of said latches at one step thereof operating to unlatch said switching member for movement in one direction from one position thereof, and concurrently to place the next adjacent step in line for engagement with the other member to latch the switching member in its next succeeding position.

2. An electrical switch comprising separable housing portions, an operator movably connected to said housing between the portions thereof, an operating mechanism installed as a unit between said housing portions in coupled relationship with said operator to be actuated thereby, and a unitary contact-spring assembly removably mounted between said housing portion and brought automatically into and out of coupled relationship with said operating mechanism in the mounting and removal of the assembly into and out of the housing.

3. A switch construction including a'switch unit comprising contact-carrying springs and intermediate insulating plates clamped together in stacked relation; and a housing for said switch unit having openings therein at places where said springs emerge from the stack assembly, said openings being circular and adapted to receive a spring-adjusting tool having a cylindrical shank, and the edges of said openings forming journal bearings for said shank whereby to guide the tool into engagement with the respective springs of the stack assembly and hold the tool for rotational adjusting movement.

4. An operating mechanism for a multi-position snap switch comprising a frame; a reciprocative switch member latchable into successive switch positions to said irame; a pair of slides on said member spring pressed towards one another; abutment means on said member defining a minimum spacing between said slides; an actutact points, which is effective in producing a clean making and breaking of the points without bouncing; and that, by making up the switch from separate unitary assemblies, the overall assembling I of the switch is very much simplified.

While I have illustrated my invention in terms of a three-position switch, no unnecessary limembodiments herein disclosed are subject to Also theating member movably connected to said frame and held yieldably between said slides in a neutral position in relation to said switch member; and means controlled by said actuating member for unlatching said switch member.

5. In a multi-position snap switch: the combination of a housing split into two sections; a snap mechanism in said housing including a frame slidably connected to said housing between said sections and adapted for connection to switch contact elements; actuating means for said switch movably connected to said housing between said sections; and a yieldable coupling between said actuating means and said frame comprising a pair of movable members on said frame yieldably pressed towards one another into inner spaced-apart positions, said actuating means having a portion interposed between said members.

bination of a housing having a mountingicollar thereon, said housingbeingysplit substantially along a center, plane through said collar two substantially identical half sections; an actuating lever for-the switch pivoted to said collar betweensaid sections; a switching member movably connected to said sections and adapted for.

' said parts being limited in their inward movements to define a gap of minimum'width there! between into which an inner end portion of said lever proiectuand a pair of latch pawls controlled by said lever and operativeiy interposed between said switching member and said housin '1. In a switch: the combination of a housing provided with a mounting collar and with an opening, said housing being split through said collar and opening into two sections; a switch operating mechanism within said housing including a switching member movably connected to said sections; an actuating lever pivoted to said collar between said sections and coupled to said switching member; and a contact spring assembly detachably coupled to said switching member and movably mounted in said housing for removal through said opening, said switching member and spring assembly being adapted tobe coupled and detached automatically from one another upon inserting and removing said assembly into and out of said housing through said opening. I

8. In an electrical switch: the combination of a split housing provided with interior abutments; a unitary snap mechanism movably connected to said housing between the sections thereof and including latch pawls engaging" said abutments; and an actuating member for said switch also movably connected to said'housing between said assa io 6. In a multi-posit1on snap switch: the com-. 7

- mount the .housing to the panel, said housing being split through said collar into two separate be inserted through an aperture in spam! to sections; an actuating lever pivoted to said collar between said sections and having an outwardly extending arm adapted for manipulation and an inner arm extending into the housing; a unitary snap mechanism in said housing comprising abase structureslidably connected to said sections. two members movably mounted on said base another and restricted in their inward travel whereby to confine said lever yieldingly to a neutral position in relation to said base structure; spaced abutments within said housing; oppositely directed latch pawls pivoted to said base" structure and biased into engagement with said abutments, said pawls being released by said members respectively in response to movements of said lever in opposite directions out of said neutral positions; and switch contact springs mounted in said housing and coupled to said base structure to be actuated thereby.

12. In a multi-position snap switch: the combination of a housing; a snap mechanism including a switching member movabiy connected to said housing and adapted for connection to switch contact elements; a rod mounted on said switching member and having a central enlargeddiameter portion providing spaced-apart shoulders; two members slidably mounted on the outer end portions of said rod and spring pressed towards one another against said shoulders; and an actuator for said switch having a part interposed between said two members to couple the actuator tosaid snap mechanism.

13. In a multiple-throw snap switch including a frame member, a reciprocable switch contact 'member mounted on said frame member and switch contact member for moving the latter sections, said actuating member being detachably coupled to said unitary snap mechanism.

9. In amulti-position snap switch: the .combination of a housing having inwardly projecting parallel teeth on an interior wall thereof; a switching member in said housing mounted for movement transverse to said teeth: and latch pawls for said switching member having faces adapted for engaging said teeth respectively, said faces extending parallel to said teeth along the length thereof whereby to provide a large surface contact between said pawls and said teeth.

10. An operating mechanism for a multi-position snap switch comprising a switch frame; a reciprocative switch member carried by said frame; means for latching said switch member selectively into a plurality of switch positions including oppositely directed latch pawls pivoted to said switch member and stationary catch means on said frame and engaged by said pawls; a pair of slides on said member spring pressed in opposite directions; abutment means defining limiting positions for said slides; means actuatable to move said slides selectively in opposite direction into'constrained positions in relation to said switch member; and means to disengage said latch pawls from said catch means by said slides respectively.

11. In a multi-position snap switch: the combination of a housing having a collar adapted to back and forth into its respective switch positions: the combination of a pair of oppositely directed one-way latches, comprising oppositely directed ratchet-toothed means on one of said members and respectively cooperating pawls on the other of said members, for securing said switch contact member against movement in opposite directions relative to said frame member at said several switch positions respectively; and means coupling said mechanism to said latches for disengaging said latches selectively according to the direction of actuation of said mechanism.

14. In a multiple-throw snap switch including a frame member, a reciprocable switch contact member mounted on said frame member and having at least three switch positions in succession, and a manually reciprocable mechanism on said frame member and yieldably coupled to said switch contact member for moving the latter back and forth into its respective switch posi; tions: the combination of a pair of oppositely directed one-way latches between saidframe and switch members for latching said switch member against movement in either direction at said several switch positions respectively, said latches comprising two sets of abutments on one of said members and oppositely directed pawls on the other of said members, said pawls engaging said two sets of abutments respectively; and means coupling said mechanism with said pawls for disengaging said pawls selectively according to the direction of actuation of said mechanism.

15. In a multiple-throw snap switch including a frame, a switch contact element movably mounted on said frame and having at least three switch positions in succession, and a manually reciprocable mechanism on said frame and yieldabiy coupled to said switch contact element for moving the latter back and forth into its several switch positions respectively: the combination oi catch means connected to said switch contact element ior movement therewith: relatively movable latch means on said frame comprising two sets of abutments spaced along the path of movement 0! said catch means. said latch means being controllable to place the respective abutments of each set into and out of the path of said catch means, the diiierent abutments oi one set being adapted to be placed selectively into said path to latch said switch contact element at diiierent switch positions against movement in one direction and the diiierent abutments oi the other set being' adapted to be placed selectively into- CHARLIE W. DANN.

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