US2505831A

US2505831A - Electric switch

Info

Publication number: US2505831A
Application number: US582216A
Authority: US
Inventors: Alvin W Krieger
Original assignee: Cutler Hammer Inc
Current assignee: Cutler Hammer Inc
Priority date: 1945-03-12
Filing date: 1945-03-12
Publication date: 1950-05-02
Anticipated expiration: 1967-05-02

Description

y 1950 A. w. KRIEGER 2,505,831

ELECTRIC SWITCH Filed March 12, 1945 3 Sheets-Sheet 1 May 2, 1950 Filed larch 12, 1945 A. w. KRIEGEfi ELECTRIC SWITCH 3 Sheets-Sheet 2 y 1950 A. w. KRIEGER 2,505,831

ELECTRIC swncu Filed March 12, 1945 3 Sheets-Sheet 3 humans, 2, 1950 ELECTRIC swrrcn Alvin W. Krieger, Milwaukee, Wis., clinics to Cutler-Hammer, Inc., Milwaukee, Win, a corporation of Delaware Application March 12, 1945, Serial No. ssazis 18 Claims. 1

This invention relates to improvements in electric switches, and, although not limited thereto, the invention relates more particularly to snap switches for use in high capacity overload circuit breakers for aircraft service.

A primary object of the invention is to provide a high capacity electric snap switch of improved and simplified form.

Another object is to provide such a switch having novel manual means for operating the same for completing or interrupting the controlled circuit at will, together with means for insuring automatic circuit interrupting operation'thereof under certain conditions.

Another object is to provide a high capacity overload circuit breaker of extremely rugged, simple and durable construction which is not likely to get out of order.

Another object is to provide novel means for insuring a good electrical connection between the switch contactor and the bimetallic electro-- thermally responsive element associated therewith, while minimizing the effect of such electrical connection upon the operative characteristics of the switch.

Another object is to provide novel means for minimizing the amount of heat dissipated from the operative portion of the bimetallic element to the conductive elements associated therewith.

Another object is to provide novel means for insulating the switch mechanism from the operating member associated therewith.

Another object is to provide a novel arrangement of spring means for normally tending to bias the switch to its circuit interrupting position. Another object is to provide such a high capacity circuit breaker which may be manually held in circuit completing condition regardless of overload.

Other objects and advantages of the invention will hereinafter appear.

-The accompanying drawings illustrate a preferred embodiment of the invention which will now be described; it being understood that the embodiment illustrated is susceptible of modification in respect of certain structural details thereof without departing from the scope of the appended claims.

In the drawings, Figure 1 is a top plan view (actual size) of a high capacity electro-thermally responsive overload circuit breaker constructed in accordance with my invention.

Fig. 2 is a sectional view, on the line 2--2 of 2 p the parts thereof in circuit completim position;

certain of the switch parts being shown in elevation.

Fig. 3 is a bottom plan view of the circuit breaker.

Fig. 4 is a sectional view quite similar to that of Fig. 2, but with all of the visible switch parts shown in elevation in circuit interrupting position.

Fig. 5 is a transverse sectional view, substantially on the line 5-5 of Fig. l, but with certain of the switch operating parts shown in elevation.

Fig. 6 is a sectional view, on the line 6-8 of Fig. 3, illustrating the bimetallic electro-thermally responsive strip and the latching means associated therewith.

Fig. 7 is an end elevational view of the switch unit, taken on the line 1-1 of Fig. 2.

Fig. 8 is an opposite end elevational view of Fig. 3, illustrating the switch mechanism, with the switch unit, taken on the line H of Fig. 2, and

Fig. 9 is a top plan view of the electro-thermally responsive bimetallic strip and the associated contactor, illustrating the novel form of said strip, and the novel form of flexible electrical connection between the same and said contactor.

In the drawings, the numeral l5 designates a one-piece insulating base adapted to be produced by a straight-line molding operation; said base being of substantially rectangular, box-like contour, and the same having therein a substantially rectangular recess l6 opening to the upper end thereof. The end walls l1 and ll of base l5 are provided at their mid-width with inwardly projecting ribs i9 and 20 of substantially rectangular form in transverse cross section; said ribs ending in a common plane below the upper end of the base, as indicated at 2| and 22 in Fig. 4; said end walls having rectangular upwardly opening notches formed therein, as shown at 23 and 24 in Fig. 4, the lower ends of the respective notches being located in the plane of the upper ends of said ribs l9 and 2..

Located centrally of the transverse areas defined by each rib l9 and 20 and the adjacent portions of end walls I! and I8 respectively alined therewith are the substantially cylindrical

auxiliary recesses

25 and 28; the depth of which recesses is indicated in dotted lines at the left-hand side of Fig. 4.

Recesses

25 and 26 are respectively adapted to accommodate, or provide clearance for, a pair of bolts or screws (not shown) which have threaded eng ement with locknuts 21 of known form to secure the device as a whole to the inner surface of a supporting panel.

Locknuts 21 are permanently and non-rotatably attached to a punched and stamped sheet metal cover member 28, as by upsetting or riveting the upper ends 21 of the former over the upper surface of the latter; member 28 having downward offsets or extrusions 28 to be engaged by rectangular portions 2! of said locknuts 21 to prevent rotation of the latter. 1

Base I5 is provided at each of its four corners with molded-in metal inserts, of the contour shown in dotted lines at 29 in Fig. 6, each insert having a reduced hollow upper end, and member 28 having openings at its corners to fit over said reduced ends; the latter being spun over the outer surface of member 28, as shown at 29 (Figs. 1 and 6) to rigidly and permanently attach member 28 to said base in a peripherally substantially dust-tight relationship thereto.

Member 28 is provided centrally thereof with a substantially circular opening to accommodate the reduced lower end of a hollow metal bushing 30, which end is upset over the lower surface of member 28, as shown at 30, to permanently secure said parts in assembled position. Said reduced end of bushing 30 is provided at one point with a rectangular notch or cut-away portion into which an integral lug of corresponding size, as shown at 28 in Fig. 4, is adapted to fit to positively prevent rotation of said .bushing relatively to member 28. Bushing 33 is provided with diametrically opposed countersunk openings 30' and 30 to accommodate a headed pivot pin 3!, whose shank end is upset, as shown in Fig. 5, to retain said parts in assembled relation.

Pin 3| extends freely through a transverse opening 32 (Fig. 4) in an approximately spherical enlargement 32 of a manually operable lever 32, the substantially spherical outer end of which is designated by numeral 32. Lever 32 is provided below enlargement 32 with a cylindrical portion 32 of relatively small diameter; said portion 32 being adapted to abut against the inner end of lug 28 and the lower end of bushing 30, as indicated in Fig. 4, to limit movement of lever 32 in opposite directions respectively. Formed integrally with the lower end of portion 32 is a cylindrical enlargement 32 having a circular opening extending diametrically therethrough, in a plane parallel to the opening 32 through enlargement 32 to accommodate a pin 33 the ends of which extend substantially like distances from the respective sides of portion 32. Any suitable means may be employed to restrain pin 33 against endwise displacement from portion 32, and in practice I prefer to provide a straight knurl (not shown) upon the mid-portion thereof to provide for a drive fit thereof into said opening in portion 32.

As best illustrated in Fig. 5, the respective ends of pin 33 are adapted for cooperation with an insulating actuating element 34 of the switch and with an insulating block 35 associated with the bimetallic electro-thermally responsive latching elements of the circuit breaker. Referring first to the switch mechanism, the same comprises a punched and stamped sheet metal frame member 36 of substantially U-shape in transverse cross section; the connecting portion 36' thereof being rigidly attached, as by means of a pair of screws 31, to the flat ledge or projection l5 upon the bottom wall of recess I 6. The parallel sides of frame 36 as punched are of like form, as best illustrated in Figs. 4 and 2.

Thus, each side is provided at its rear end with an arcuate portion, 38 and 36, extending slightlybelow the level of portion 36', said arcuate portions having alined circular openings formed therein for registry with openings of corresponding size in the

respective arms

38 and 38 of a contactor 38 located upon the exterior of the frame. A headed pin 39 extends through said registered openings to provide for pivotal support of the contactor by the frame; the shank end of said pin 39 being upset as shown in Figs. 7 andB. The forward ends of

contactor arms

38 and 38 are integrally connected by the flat portion 38 (Figs. 2, 4 and 7), to the'iower surface of which a tip 40 is spot-welded, brazed, or otherwise rigidly attached. Tip 40 is preferably molded in a known manner from a suitable silver base powdered material.

The bottom wall of recess I6 is provided with a countersink l6"- of hexagonal or other suitable contour to accommodate the correspondingly shaped head 4 i"- of a combined stationary contact and terminal member 4!, the threaded shank portion of which is designated by the numeral 4!"; said bottom wall being provided with an opening l6 (Figs. 2 and 4) to provide clearance for said shank. An ordinary metal washer 42, a lock washer 43, and a nut 44 are assembled upon said shank at the lower surface of base l5 to secure said combined contact and terminal member to the base. An additional washer 45, lock washer 46 and nut 41 are positioned upon the lower threaded end of said shank to provide for clampingly connecting a circuit wire (not shown) between the same and nut 44. Said head 41* has spot-welded or otherwise rigidly attached thereto a contact tip 40 for cooperation with the contactor tip 40 aforementioned.

Contactor arms

38 and 38 are provided adjacent their forward ends with alined openings to accommodate the shank of a headed pin 48 (Figs. 2, 4, and 7) the end of which shank is upset to retain the same in assembled position. Pin 48 also penetrates alined openings in the lower end portions of a pair of

arms

49, 49 to afford a pivotal connection between said arms and the contactor. The connecting portion 38 and arms 38' and 38 are cut away at opposite sides of the contactor, as illustrated at W in Fig. 4 and in dotted lines at 38 and 38' in Fig. 7; and as shown in Fig. 4 the lower end of each arm 49 overlaps the side edge of the connecting portion 38 to maintain-the lower ends of said arms a predetermined distance apart (Figs. 5 and 7). Arms 49 are also provided adjacent their upper ends with openings to accommodate the shank of a headed pivot pin 38; said last mentioned openings preferabl being of elongated or substantially elliptical form, as indicated in dotted lines at 49' in Fig. 4, to provide a predetermined degree of lost motion of pin 58 with respect thereto. In practice a washer N (Fig. 7) is positioned upon the shank end of pin 50 to facilitate spinning or upsetting of said end without binding or clamping of the parts connected thereby.

Positioned inside of the respective arms 49 are a pair of links 82, 52 whose forward ends are likewise perforated to accommodate the shank of pin a spool-shaped or double-flanged roller 53 being interposed between said ends of link 52 and rotatably supported upon pin 50. Links 82 are of elongated, downwardly curved contour, as best illustrated in Fig. 2, the rear ends thereof having circular openings formed therein (as shown in II dotted lines in Figs. 4 and 8) to accommodate the ano es:

reduced cylindrical portions of a cylindrical spacer pin, the main portion of which is desi nated by numeral 54. Said cylindrical portions of pin 64 are of only slightly greater length than the thickness of the respective links 52 and have their outer ends spun or upset over the outer surfaces of said links, as indicated at 54 in Fig. 4.

The extreme outer end portions of pin 54 are of a still further reduced cylindrical form, as indicated at 54 and 54 in Figs. 4 and 7; the frame sides having rearwardly

opening slots

36 and 36 formed therein to accommodate and guide said end portions of the pin. A double-armed coiled torsion spring 55has one straight end portion of each arm engaged with the inner surface of-the connecting portion 36 of the frame, as shown at 65'- in Fig. 2; each arm also having a plurality of

coils

55 and 55 formed thereon and surrounding the aforementioned pin 39. The relatively long inverted U-shaped intermediate portion of spring 65 is arranged with its upper end overlapping and continuously engaged with the inner periphery of pin 54, whereby the

aforementioned end portions

54 and 54 are biased outwardly with respect to slots 36 and 36'. Complete disengagement of pin 54 from

slots

36 and 36 is prevented in the following manner:

The aforementioned insulating actuating element 34 has molded therein in the central plane thereof a metal cam member 56 of the contour best illustrated in Fig. 2. Member 56 is provided with a relatively large cut-away portion or notch. shown in dotted lines at 56 in Fig. 2, to afford electrical clearance .between member 56 and a headed pin 51, the shank of which penetrates alined openings in the sides of frame 36 and in the element 34 to afford pivotal support of the latter-with respect to the frame. The edges of notch 56 project inwardly toward each other at the upper ends thereof (as indicated in dotted lines at 56 and 56) to insure a good mechanical connection or interlock between element 34 and member 56.

Element 34 is provided with a symmetrically arranged upwardly opening notch 34 the opposite walls of which are closely adjacent to that end of pin 33 positioned therewithin, while permitting relative movement of said pin with respect.there to as an incident to the arcuate path of movement of the pin. Element 34 is provided on opposite sides thereof with cylindrical lateral extensions or

bosses

34 and 34, which are respectively adapted to overlie and temporarily engage the upp r edges of the frame sides to limit the degree of clockwise movement of element 34 with respect to the frame (under the bias of spring 55) pending assembly of the lever 32, as will be apparent from consideration of Fig. 2. Member 56 is provided with a pair of cam edges or surfaces 56 and 56 inclined toward each other to meet at the point 56; said surfaces bein preferably of outwardly curved or convex formas illustrated.

With the parts assembled and positioned as shown in Fig. 2, the spring 55 will act against pin 54 to draw links 52 toward the right, thus forcing the roller 53 against the cam surface 56 the force of said spring being likewise transmitted through pin 58, arms 49 and pin 48 tocontactor 38 to hold the tip 48 thereof against the contact tip 48 with a predetermined degree of pressure. Upon clockwise movement of lever 32, the cam surface 56 will act against roller 53 to move the same toward the left, thus temporarily increasing the degree of pressure of the contactor tip 48 against the stationary contact, du to an increase 6 in the degree of torsion of spring 56. However, when the point 56 of the cam has passed over center with respect to roller 53, the spring 68 will act through the aforedescribed parts to eifect snap movement of said roller toward the rear end of cam surface 56, thus snapping the contactor to its circuit interrupting position, as shown in Fig. 4.

Also as shown in Fig. 4, the portion 32 of lever 32 is adapted to abut against the inwardly projecting lug 28" on cover member 28 to limit the degree of clockwise movement of said lever and consequently the degree of counterclockwise movement of element 34. The sides of frame 36 are respectively provided with outwardly bent integral lugs 36 and 36 (Figs. 4 and 5) with the flat lower surfaces of which the upper edges of the contactor arm 38' and 38 are adapted to engage to positively limit the circuit interrupting throw of contactor 38.

As will be apparent from Fig. 4, on counterclockwise movement of lever 32 the cam surface 56 will act in substantially the same manner as aforedescribed to increase the degree of torsion of spring for holding the contactor in circuit interrupting position, until the aforementioned point 56 (moving clockwise) passes over center in the opposite direction with respect to roller 53 (Fig. 2), whereupon the contactor will snap to the circuit completing position illustrated in Fig. 2; it being understood that the portion 32 engages the lower end of bushing 30 to limit the counterclockwise throw of lever 32, and the pin 33 on the latter cooperates with the left-hand wall of notch 34' of element 34 to limit the clockwise throw of the latter and the degree of movement of links 52 toward the right (Fig. 2). Thus, as illustrated in Fig. 2, the

aforementioned projections

34 and 34 are not normally utilized to limit the movement of the parts in the circuit com pleting position of the switch.

The aforedescribed switch parts are so formed as to facilitate assembly thereof. In practice, the contactor 38 may have attached thereto arms 49, roller 53, and links 52 by the

aforementioned pins

48 and 56, and spacing pin 54 may be rigidly attached to the rear ends of links 52. This subassembly of parts may be readily positioned with respect to frame 36 so that the perforated rear ends of the contactor arms, which straddle the frame, are alined with the frame openings to accommodate pin 38; the torsion spring 55 being properly positioned within the frame so that the

coils

55 and 55 thereof will also accommodate pin 33. The U -shaped upper end portion of spring 55 is engaged with the inner periphery of spacer pin 54 prior to insertion of the reduced ends 54 and 54 of the latter within

slots

35 and 36 of the frame sides.

A suitable ji or the like (not shown) may be provided for holding said ends 54 and 54 within the frame slots, against the bias of spring 55, in order to provide clearance for proper insertion of the unit consisting of cam member 56 and insulating element 34 between the frame sides for alinement of the opening or passage through the latter with the openings in the frame sides which accommodate the pivot pin 51. Frame 36 may then be secured to the bottom wall of recess l6 by the screws 31, as shown in Fig. 2. After tightening of screws 31, the countersink accommodating the heads thereof is preferably at least partially filled with a suitable cement or wax, as indicated at 58 in Figs. 2, 4 and 5 to prevent accidental loosening of said screws.

If only a switch mechanism is to be housed asoasss within base II a multiple strand flexible wire connector or bus member (not shown) may be rigidly attached by spot welding, brazing or the like at one end of arm I! of contactor 3| near the point of pivotal support of the latter, the other end of said connector being electrically and mechanically connected in alike manner to the other terminal member 4|, 4| and its associated parts 42 to 41, shown in Fig. 6 and in Figs. 2 and 4.

With the switch parts assembled with respect to base It, the cover member 28, with its assembled

parts

30, 3i and 32, may be positioned so that one end of pin 33 enters the slot 34" in element 34. The openings at the four corners of member 28 are pressed downwardly over the positioning ends of the inserts 2!; said ends being then upset as shown at 29' in Figs. 1 and 6 to rigidly and permanently secure member 28 in position.

As aforestated, the high capacity electric snap switch just described is utilized as a part of an electro-thermally responsive circuit breaker; and for this purpose base it is of sufilcient width to accommodate a bimetallic electro-thermally responsive strip and the latching elements associated with the same and with the switch mechanism. As best illustrated in Figs. 6 and 9, a punched bimetallic strip 58 of suitable caliber has its opposite ends 59 and 59 of reduced width, and respectively provided with end-opening

notches

59 and 59 The walls of said notches are adapted to fit around the reduced or neck portions 60 of a pair of like machined supporting bolts or screws designated by numerals 60, 60 (Figs. 5 and 6). Said notched ends 59 and 59 underlie shoulders formed by the kerfed heads or upper ends 66' of bolts 60; the latter being provided below necks 60' with enlarged cylindrical portions 60, and still further enlarged cylindrical flange portions 60, upon the flat upper surfaces of which coiled compression springs 6i are adapted to seat. The upper ends of springs 6| bear, with like degrees of pressure, against the lower surfaces of said end portions 59" and 59 Bolts 60 are provided with externally threaded lower portions 60' which cooperate with correspondingly threaded passages or openings I 5 and l5 in base iii.

In practice the right-hand bolt 60 is threaded into opening l5 until the lower surface of flange I an abuts against an integral shoulder or ledge i5 (Fig. 6) formed within recess 16. The lefth nd bolt 60 is initially threaded into opening 15 to a degree to effect substantially horizontal positioning of strip 69, the ledge Iii formed within recess it being located a substantial distance below flange Bi on said bolt 60. The openings i5 and i5 have countersinks or recesses l5 and I5 at the lower ends thereof, into which the kerfed lower ends 60 and 60' of bolts 60 are adapted to extend. After complete assembly of all of the parts of the circuit breaker the lefthand bolt 60 may be adjusted by use of a screwdriver at the lower end 60 thereof to locate bimetallic strip 59 in the proper plane for the desired operation of its associated latch element 62 with respect to the reciprocable latch element 66 of the device. Said latch element 62 has its horizontal portion 62' spot-welded, brazed or otherwise rigidly attached to the upper surface of strip 59 at a predetermined point in the length of the latter and preferably at the mid-point of the width thereof. After the required adJustment of left-hand screw 60 has been effected, the countersinks i5 and It may be partially filled with cement or wax. as shown. to prevent accidental loosening of said bolts, and to seal the same against tampering.

Strip 6! preferably has spot-welded or otherwise rigidly attached to the lower surface thereof at points spaced a predetermined distance from each other a pair of

rectangular blocks

63, 63 formed of copper or other suitable metal. Strip 59 has a pair of relatively narrow rectangular openings 89' and It formed therein (Figs. 6 and 9) the outer walls of said openings being arranged in flush relationship to the inner sides of the respective blocks 63. The openings 59' and 59' serve as "heat blocks" to minimize the amount of heat conducted from strip 69 to blocks 63 and the connectors associated with the latter; thus insuring maintenance of proper calibration of the active portion of said strip. The right-hand block 43 is electrically connected by a multiple strand connector or bus member 63* with the head 4! of a second wiring terminal member (Fig. 6); said polygonal head 4| being located within a pocket or recess l5, and said connection preferably being effected by spot-welding of the opposite ends of member 63 to block 63 and to head 4|- respectively. Base I5 is provided with an opening l5 to accommodate the threaded shank 4 l of said terminal member, and nuts and washers like those aforedescribed are associated with said shank.

Recess I6 is provided with a pair of relatively small ledges in each end wall thereof, one of which is shown at IS in Fig. 5, and with a ledge along the major portion of one side wall thereof, as indicated at i5 in said figure. A punched and stamped sheet metal bracket 64 has its main body portion seated upon said ledges (Figs. 5 and 6) said bracket having opposite end portions 64- and 64 of reduced width adapted to fit within vertical grooves l6 and ii in the end walls of recess it to prevent substantial lateral displacement of said bracket. End portion 64 is provided with an integral extension 64 bent upwardly at substantially a right angle thereto; said extension having a circular boss 64 projecting inwardly therefrom (Fig. 6) to provide a springcentering abutment. As shown in Fig. 5, bracket 64 is provided along the inner edge thereof with a relatively short upstanding flange 64' which is adapted for slidable engagement by the walls of groove 35 in the lower surface of the molded insulating block 35 aforementioned. Block 35 has fiat surface portions (Figs. 5 and 6) overlying bracket 64 but normally said surfaces are held upwardly out of engagement with the bracket as hereinafter described. The flat upper surface portions 35 of block 36 are normally adapted to bear against the inner surface of cover member 28, as shown in Figs. 5 and 6.

The means for biasing block 35 upwardly comprises a leaf-spring 65 bent upwardly at its midlength, as best illustrated in Fig. 6. Spring 65 is positioned within a downwardly opening. shallow rectangular recess 35 in the lower surface of block 35; said recess being only slightly wider than spring 65, as shown in Fig. 5. Recess is adapted to accommodate, in a flush relationship to the lower surface of block 35, the main body portion of a punched and stamped sheet metal latch member 66; member 66 having a flange 66' upstanding at substantially a right angle thereto at the left-hand end thereof (Fig. 6)

.for positive engagement by the vertical end wall 35 of recess 36 during manual setting or resetting of said latch as an incident to manual tw operationofleverfltoeifecteiosureofthe lo a in disclosed provides for manual movement of the switch to, and/or retention thereof in, circuit completing position regardless of the condition of the bimetallic strip 66 and the latch element 63 carried thereby.

I claim: 1. The combination with a pivoted switch actuating member having edge portions arranged in the form of a pointed double inclined cam, of

latch member 66 downwardly into engagement with bracket 66. Member 66 has a tongue 66 partially sheared therefrom and bent downwardly at a predetermined angle with respect thereto, as best illustrated in Fig. 6, to form the manually movable latch element of the device. Bracket 66 is provided with an elongated rectangular slot 66 of substantially greater width than latch element 66 to afford reciprocating clearance for the latter. 7

Block 36 is provided with a recess 36* opening upwardly and laterally toward the lower end of lever 32 to accommodate the right-hand projecting end of pin 33 (Fig. 5). The vertical wall 36' of recess 36 is engageable by said end of pin 33 to forcibly move block 36 and its associated parts toward the right (Fig. 6) to effect interlockin engagement of latch 66 with latch 62, as an incident to movement of the switch parts to circuit completing position by the left-hand projecting end of pin 33 (Fig. 5). Such movement of block 36 is opposed by the action of coiled compression springs 61 and 66; one end of each of which engages the extension 66 of bracket 66 and is centered by the aforementioned abutment 66 on said extension. The other end of each

spring

61 and 66 engages the end wall 36 of a cylindrical recess 36 which opens to the right-hand end of block 36 (Fig. 6).

Springs

61 and 68 are preferably formed of wires of different sizes, and the same are wound in opposite directions with their coils of substantially different diameters. Thus spring 66 may be readily inserted or nested within spring 61; the reverse winding of the springs insuring against interweaving or fouling of one spring with respect to the other. The arrangement illustrated minimizes the space requirement for the spring biasing means for block 36, and enables more accurate predetermination of the spring pressure applied to block 36 in various different positions thereof.

Prior to assembly of contactor 36 with respect to frame 36 in the manner aforedescribed, I prefer to spot-weld or otherwise rigidly attach to the exterior of the arm 36 of the former,'near the point of pivotal support thereof, one end of each of a pair of multiple strand connectors or

bus members

69 and 16; the other end of each of said bus members being likewise spot-welded to the left-hand copper block 63 (Figs. 9 ahd'6). This arrangement has an obvious advantage over the use of a single heavier bus member of the required current carrying capacity, in that greater flexibility is afforded, to minimize the resistance to oscillatory movement of contactor 36. At the same time greater heat radiating surfaces are provided, so that the total number of wire strands required in the bus members 66 and I6 jointly may actually be smaller than the number required in a single bus member of corresponding current carrying capacity.

As will be apparent, the circuit breaker heremeans for moving said actuating member in opposite directions, a pivoted contact lever, an arm pivotally connected with said lever and provided with a part adapted to bear against said double inclined cam edge portions, a link pivotally connected to said arm, and a spring adapted to continuously bias said link in one direction, to thereby provide for snap movement of said arm and said lever in either direction substantially independently of said actuating member indifferent 1 positions of the latter.

2. In an electric snap switch, in combination, a pivoted actuating member having edge portions arranged in the form of an outwardly pointed double inclined cam, manually operable means for moving said actuating member in opposite directions, a pivoted contact lever, an arm pivotally connected withsaid contact lever and provided with a roller adapted to bear against the double inclined cam edge portions alternately according to the position of said actuating member, a coiled torsion spring for continuously biasing said arm to hold said roller in engagement with said actuating member, a second arm having a pivotal connection with the free end of said first mentioned arm, means providing a lost motion support for said second arm at the other end of the latter, and .said spring cooperating with said first and second arms to effect snap movement of said contact lever to opposite extreme positions upon given degrees of movement of said actuating member in opposite directions.

3. In an electric snap switch, in combination, a pivoted actuating member having edge portions arranged in the form of an outwardly pointed double inclined cam, a pivoted manually operable lever having a pin and slot driving connection with said actuating member for moving the latter alternately in opposite directions, a pivoted contactor, an arm pivotally connected with said contactor and provided with a roller adapted to bear against said double inclined cam edge portions al-v ternatively according to the position of said actuating member, a coiled torsion spring, a second arm having a pivotal connection with thefree end of said first mentioned arm, means providing a lost motion support for said second arm at the other end of the latter, said spring cooperating with said first and second arms to continuously bias said roller against said actuating member, to thereby eifect snap movement of said contactor to opposite extreme positions upon given degrees of movement of said actuating member in opposite directions.

4. In an electric snap switch, in combination, an insulating base member, a punched and formed sheet metal frame member of substantially U-shape in transverse cross section, means for rigidly attaching the connecting portion of said frame to said base member, a punched and formed sheet metal cont-actor having a forward end of substantially U-shape in transverse cross section and an integral pair of rearwardly extending parallel arms, a pin penetrating alined openings in said arms and said frame for supporting said contactor for pivotal movement relatively to 11 said frame, an arm pivotally attached to the forward-end of said contactor, a link pivotally attached to the free end of said last mentioned arm, the rear end of said link having a pin and slot connection with said frame, a torsion spring having its coils surrounding said first mentioned pin, one end portion of said spring being engaged with said frame and another end portion being engaged with said rear end of the link to normally bias the latter toward a given position relatively to said frame, an actuating member pivotally supported by the frame adjacent the upper end thereof, said actuating member having edge portions arranged in the form of an outwardly pointed double inclined cam, and a roller rotatably supported by said link and said arm at the point of pivotal connection therebetween, said edge portions of said actuating member cooperating with said roller to insure snap movement of said contactor from each extreme position to the other upon given degrees of movement of said actuating member in opposite directions respectively.

5. In an electric snap switch, in combination, an insulating base member, a punched and formed sheet metal frame member of substantially U-shape in transverse cross section, means for rigidly attaching the connecting portion of said frame to said base member, a punched and formed sheet metal contactor having a forward end of substantially U-shape in transverse cross section and an integral pair of rearwardly extending parallel arms, a pin penetrating alined openings in said arms and said frame for supporting said contactor for pivotal movement relatively to said frame, an arm pivotally attached to the forward end of said contactor, a link pivotally attached to the free end of said last mentioned arm, the rear end of said link having a pin and slot connection with said frame, a torsion spring having its coils surrounding said first mentioned pin, one end portion of said spring being engaged with said frame and another end portion being engaged with said rear end of the link to normally bias the latter toward a given position relatively to said frame, an actuating member pivotally supported by the frame adjacent the upper end thereof, said actuating member having edge portions arranged in the form of an outwardly pointed double inclined cam, a roller rotatably supported by said link and said arm at the point of pivotal connection therebetween, said edge portions of said actuating member cooperating with said roller to insure snap movement of said contactor from each extreme position to the other upon given degrees of movement of said actuating member in opposite directions respectively, said actuating member having an outwardly opening slot formed in the upper edge thereof, and a pivoted manually operable lever having at its lower end a pin engageable with the walls of said slot to alternately effect such opposite movements of said actuating member.

6. In an electric snap switch, incombination,

an insulating base member, a punched and,

porting said contactor for pivotal movement relatively to said frame, an arm pivotally attached to the forward end of said contactor, a link pivotally attached to the free end of said last mentioned arm, the rear end of said link having a pin and slot connection with said frame, a torsion spring having its coils surrounding said first mentioned pin, one end portion of said spring being engaged with said frame and another end portion being engaged with said rear end of the link to normally bias the latter toward a given position relatively to said frame, an actuating member pivotally supported by the frame adjacent the upper end thereof, said actuating member having edge portions arranged in the form of an outwardly pointed double inclined cam, a roller rotatably supported by said link and said arm at the point of pivotal connection therebetween, said edge portions of said actuating member cooperating with said roller to insure snap movement of said contactor from each extreme position to the other upon given degrees of movement of said actuating member in opposite directions respectively, said actuating member having an outwardly opening slot formed in the upper edge thereof, a pivoted manually operable lever having at its lower end a stud engageable with the walls of said slot to alternately effect such opposite movements of said actuating member, the parallel sides of said frame having transversely extending integral lugs engageable jointly by the parallel arms of said contactor to limit movement of the latter in one direction, and .a stationary contact carried by said base and engageable by said contactor to limit movement of the latter in the opposite direction.

7. In an electric snap switch, in combination, an insulating base member, a punched and formed sheet metal frame member of substantially U-shape in transverse cross section, means for rigidly attaching the connecting portion of said frame to said base member, a punched and formed sheet metal contactor having a forward end of substantially U-shape in transverse cross section and an integral pair of rearwardly extending parallel arms, a pin penetrating alined openings in said arms and said frame for supporting said contactor for pivotal movement relatively to said frame, an arm pivotally attached to the forward end of said contactor, a link pivotally attached to the free end of said last mentioned arm, the rear end of said link having a pin and slot connection with said frame, a torsion spring having its coils surrounding said first mentioned pin, one end portion of said spring being engaged with said frame and another end portion being engaged with said rear end of the link to normally bias the latter toward a given position relatively to said frame, an actuating member pivotally supported by the frame adjacent the upper end thereof, said actuating member having edge portions arranged in the form of an outwardly pointed double inclined cam, a roller rotatably supported by said link and said arm at the point of pivotal connection therebetween, said edge portions of said actuating member cooperating with said roller to insure snap movement of said contactor from each extreme position to the other upon given degrees of movement of said actuating member in opposite directions respectively, said actuating member having an outwardly opening slot formed in the upper edge thereof, a pivoted 7 manually operable lever having at its lower end l3 a laterally extending stud engageable with the walls of said slot to alternately-effect such opposite movements of said actuating member, the

said manually operable lever in each direction respectively, to thereby correspondingly limit the degree of movement of said actuating member in each direction.

8. In an electric snap switch, in combination, an insulating base member, a punched and formed sheet metal frame member of substantially U- shape in transverse cross section, means for rigidly attaching the connecting portion of said frame to said base member, a punched and formed sheet metal contactor having a forward end of substantially U-shape in transverse cross section and an integral pair of rearwardly extending parallel arms, a pin penetrating alined openings in said arms and said frame for supporting said con,-

- tactor for pivotal movement relatively to said frame, an arm pivotally attached to the forward end of said contactor, a link pivotally attached to the free end of said last mentioned arm, the rear end of said link having a pin and slot connection with said frame, a torsion spring having its coils surrounding said first mentioned pin, one end portion of said spring being engaged with said frame and another end portion being engaged with said rear end of the link to normally bias the latter toward a given position relatively to said frame, an actuating member pivotally supported by the frame adjacent the upper end thereof, said actuating member having edge portions arranged in the form of an outwardly pointed double inclined cam, a roller rotatably supported by said link and said arm at the point of pivotal connection therebetween, said edge portions of said actuating member cooperating with said roller to insure snap movement of said contactor from each extreme position to the other upon given degrees of movement of said actuating member in opposite directions respectively, said actuating member having an outwardly opening slot formed in the upper edge thereof, a pivoted manually operable lever having at its lower end a laterally extending stud engageable with the walls of said slot to alternately effect such opposite movement of said actuating member, the parallel sides of said frame having transversely extending integral lugs engageable joint- 1y by the parallel arms of said contactor to limit movement of the latter in one direction, a stationary contact carried by said base and engageable by said contactor to limit movement of the latter in the opposite direction, associated means for positively limiting the degree of movement of said manually operable lever in each direction respectively, to thereby correspondingly limit the degree of movement of said actuating member in each direction, means comprising a flexible conductor having one end rigidly attached to said contactor for including the latter in the circuit to be controlled thereby, and means associated with said stationary contact to provide for removable attachment of a circuit wire thereto.

9. In an electric snap switch, in combination, an insulating base member, a punched and formed sheet metal frame member of substantially U-shapeintransversecrosssectimmeans for rigidly attaching the connecting portion of said frame to said base member, a punched and formed sheet metal contactor having a forward end of substantially U-shape in transverse cross section and an integral pair of rearwardly extending parallel arms, a pin penetrating alined openings in said arms and said frame for supporting said contactor for pivotal movement relatively to said frame. an arm pivotally attached to the forward end of said contactor, a link pivotally attached to the free end of said last mentioned arm, .the rear end of said link having a pin and slot connection with said frame, a torsion spring having its coils surrounding said first mentioned pin, one end portion of said spring being engaged with said frame and another end portion being engaged with said rear end of the link to normally bias the latter toward a given position relatively to said frame, an actuating member pivotally supported by the frame adjacent the upper end thereof, said actuating member having edge portions arranged in the form of an outwardly pointed double inclined cam, a roller rotatably supported by said link and said arm at the point of pivotal connection therebetween, said edge portions of said actuating member cooperating with said roller to insure snap movement of said contactor from each extreme position to the other upon given degrees of movement of said actuating member in opposite directionsrespectively, said actuating member having an outwardly opening slot formed in the upper edge thereof, a pivoted manually operable lever having at its lower end a laterally extending stud engageable with the walls of said slot to alternately effect such opposite movements of said actuating member, the parallel sides of said frame having transversely extending integral lugs engageable jointly by the parallel arms of said contactor to limit movement of the latter in one direction, a stationary contact carried by said base and engageable by said contactor to limit movement of the latter in the opposite direction, and means comprising a pair of studs formed integrally with a part of said actuating member for cooperation with the upper edges of the respective sides of said frame to temporarily limit the degree of movement of said actuating member in one direction pending final assembly of the switch parts.

10. In a high capacity snap switch, in combination, a molded insulating base having a recess opening to the upper surface thereof, a substantially U-shaped punched and stamped sheet metal frame member having its connecting portion rigidly attached to the bottom wall of said recess, a contactor having a forward portion of channel shape in transverse cross section, the bottom wall of said channel shaped portion having a silver base contact tip rigidly attached to the lower surface thereof, said contactor having integral parallel arms arranged exteriorly of the respective frame sides, said arms and said frame sides having alined openings, a pin penetrating said openings to pivotally attach said contactor to said frame, the sides of said frame having integral lugs struck outwardly therefrom at a predetermined angle for engagement by the respective arms of the contactor to positively limit the degree of upward movement thereof, a stationary contact rigidly attached to the bottom wall of said recess, said contact having a silver base tip rigidly attached thereto for cooperation with the contactor tip to positively limit the degree of downward movement of the latter. a pair of punched sheet metal arms positioned in spaced parallel relation between the sides of the channel shaped portion of said contactor and having pivot openings formed therein adjacent the respective ends thereof, a pivot pin penetrating the sides of said channel shaped portion and one opening in each arm, a second pair of punched sheet metal arms having perforated end portions interposed between the free ends of the arms first mentioned, a metal roller interposed between said perforated end portions, a pivot pin penetrating the adjacent ends of said pairs of arms and said roller to provide for pivotal connection of said arms and rotary support of said roller, a pin attached to the free end portions of said second mentioned pair of arms and projecting laterally therebeyond, said frame sides having rearwardly opening slots formed therein to accommodate said ends of the pin, a double-armed coiled torsion spring having its end portions engaged with the connecting portion of said frame, the coils in each arm of said spring surrounding said first mentioned pin, and the refiexed intermediate portion of said spring being continuously engaged with said last mentioned pin, a pivotally supported double-inclined cam member, said spring acting to maintain said roller in continuous engagement with said cam, and the latter being adapted up"on given degrees of movement thereof in opposite directions to insure snap movement of said contactor into and out of engagement with said contact.

11. In a high capacity electric snap switch, in combination, a molded insulating base having a recess opening to the upper surface thereof, a substantially U-shaped punched and stamped sheet metal frame member having its connecting portion rigidly attached to the bottom wall of said recess, a contactor having a forward portion of channel shape in transverse cross section, the bottom wall of said channel shaped portion having a silver base contact tip rigidly attached to the lower surface thereof, said contactor having integral parallel arms arranged exteriorly of the respective frame sides, said arms and said frame sides having aligned openings, a pin penetrating said openings to pivotally attach said contactor to said frame, the sides of said frame having integral lugs struck outwardly therefrom at a predetermined angle for engagement by the respective arms of the contactor to positively limit the degree of upward movement thereof, a stationary contact rigidly attached to the bottom wall of said recess, said contact having a silver base tip rigidly attached thereto for cooperation with the contactor tip to positively limit the degree of downward movement of the latter, a pair of punched sheet metal arms positioned in spaced parallel relation between the sides of the channel shaped portion of said contactor and having pivot openings formed therein adjacent the respective ends thereof, a pivot pin penetrating the sides of said channel shaped portion and one opening in each arm, a second pair of punched sheet metal arms having perforated end portions interposed between the free ends of the arms first mentioned, a metal roller interposed between said perforated end portions, a pivot pin penetrating the adjacent ends of said pairs of arms and said roller to provide for pivotal connection of said arms and rotary support of said roller, a pin attached to the free end portions of said second mentioned pair of arms and projecting laterally therebeyond, said frame sides having rearwardly opening slots formed therein to accommodate said ends of the pin, a double-armed'coiled torsion spring having its end portions engaged with the connecting portion of said frame, the coils in each arm of said spring surrounding said first mentioned pin, and the reflexed intermediate portion of said spring being continuously engaged with said last mentioned pin, a pivotally supported double-inclined metal cam member, said spring acting to maintain said roller in continuous engagement with said cam, the latter being adapted upon given degrees of movement thereof in opposite directions to insure snap movement of said contactor into and out of engagement with said contact, said metal cam member having an insulating member molded thereonto and forming a part of the pivotal support therefor, said insulating member having a notch formed therein, and a manually operable lever pivotally supported relatively to said base, said lever having a lower end portion affording a lost motion driving connection with the walls of said notch.

12. In a device of the character described, in combination, a molded insulating base having a recess opening to the upper end thereof, a high capacity electric snap switch positioned within said. recess, said switch comprising a punched and stamped sheet metal frame member of substantially U-shape in transverse cross section, means comprising-elements penetrating the bottom wall of said recess for rigidly attaching said frame member thereto, a punched and stamped sheet metal contactor having a forward end of substantially channel shape in transverse cross section and an integral pair of rearwardly extending parallel arms, a. pin penetrating alined openings in said arms and said frame for supporting said contactor for pivotal movement relatively to said frame, a pair of punched sheet metal arms positioned in spaced parallel relation between the sides of said channel shaped portion of said contactor and having openings formed therein adjacent the respective ends thereof, a pivot pin penetrating the sides of said channel shaped portion and one opening in each arm, a second pair of punched sheet metal arms having perforated end portions overlapping the free ends of the arms first mentioned, a metal roller interposed between said perforated end portions, 2, pin penetrating the adjacent ends of said pairs of arms and said roller to provide for pivotal connection of said arms and rotary support of said roller, a pin attached to the free end portions of said second mentioned pair of arms and projecting laterally therebeyond. the substantially parallel sides of said frame having rearwardly opening slots formed therein to accommodate said ends of the pin, a doublearmed coiled torsion spring having its end portions engaged with the connecting portion of said frame, the coils in each arm of said spring surrounding said first mentioned pin, the refiexed intermediate portion of said spring being continuously engaged with said last mentioned pin, a double-inclined cam member pivotally supported within said recess, said spring acting to maintain said roller in continuous engagement with said cam member whereby upon opposite movements of the latter said contactor is moved from each extreme position to the other with a snap action, a manually operable lever pivotally supported relatively to said base and having its lower end positioned withinv said recess, an element projecting from each side of said lower end of the lever, said cam member having a notch formed in the periphery thereof 'molded insulating block having a notch formed therein with one wall of which the other proaeoaas Jecting element is adapted to cooperate to effect movement of said block to a given extreme position, spring means for biasing said block to its other extreme position to eifect circuit interrupting operation of said switch mechanism, a latch member carried by said block, a bimetallic electro-thermally responsive strip positioned within said recess and responsive to current conditions within the circuit controlled by said switch, and a latch member carried by said strip for cooperation with said first latch member to counteract the biasing eifect of said spring under predetermined normal conditions in the circuit.

13. In a high capacity electro-thermally responsive circuit breaker, in combination, a molded insulating base having a relatively large substantial-ly rectangular recess formed therein and opening to the upper surface thereof, a high capacity electric snap switch positioned within said recess adjacent one side wall thereof, said switch including an insulating actuating element pivotally supported within said recess and having a notched portion located adjacent the upper end of said recess, a bimetallic electro-thermally responsive strip adiustably supported at each end within said recess adjacent the opposite side wall thereof, a latch member rigidly attached to the upper surface of said strip between the points of support of the latter, a metal bracket supported above said strip in a predetermined space relat onship thereto, a molded insulating block located within said recess and slidable relatively to said bracket, said bracket havin a slot extending longitudinally thereof, a second latch member associated with said block and having a portion penetrating said slot for in terlocking engagement with said first mentioned latch member under normal conditions upon movement of said block to one extreme position, spring means associated with said block to normally bias the same to its opposite extreme position, said block havin a relatively large notch formed in the upper surface thereof, and a manually operable lever pivotally supported above said base, said lever having lateral projections at the lower end thereof to respectively fit within the aforementioned notches, the notch in said block being adapted to afford clearance for the projection associated therewith upon movement of said lever to effect circuit interrupting operation of said switch after initial movement of said lever to efiect circuit completing operation of said switch with coincident engagement of said latch members with each other.

14. In a high capacity electro-thermally responsive circuit breaker, in combination, a molded insulating base having a relatively large sub stantially rectangular'recess formed therein and opening to the upper surface thereof, a high capacity electric snap switchpositioned within said recess adjacent one side wall thereof, said switch including an insulating actuating element pivotally supported within said recess and having a notched portion'located adjacent the upper end of said recess, a bimetallic electro-thermally responsive strip adjustably supported at each end within said recess adjacent the opposite side wall thereof, a latch member rigidly attached to the upper surface of said strip between the points of support of the latter,a metal bracket supported above said strip inapredetermined space relationship thereto, a molded insulating block located within said recess and slidable relatively to said bracket, said bracket having a slot extending longitudinally thereof, a second latch member associated with said block and having a portion penetrating said slot for interlocking engagement with said first mentioned latch member under normal conditions upon movement of said block to one extreme position, spring means associated with said block to normally bias'the same to its opposite extreme position, said block having a relatively large notch formed in the upper surface thereof, and a manually operable lever pivotally supported above said base, said lever having lateral proiections at the lower end thereof to respectively fit within the aforementioned notches, the notch in said block being-adapted to aiford clearance for the projection associated therewith upon movement ofsaid lever to efl'ect circuit interrupting operation of said switch after-initial movem nt of said lever to effect circuit completing operation of said switch with coincident engag'ement of said latch members with each other, the aforementioned spring means acting upon disengagement of said first mentioned latch member from the second latch member as an incident to a predetermined overload condition'to effect automatic circuit interrupting operation of said switch.

15. In a high capacity electro-thermally responsive circuit breaker, in combination, a molded insulat ng base having a relatively large substantially rectangular recess formed therein and opening to the upper surface thereof, a high capacity electric snap switch positioned within said recess adjacent one side wall thereof, said switch including an insulating actuating element pivotally supported within said recess and having a notched portion located adjacent the upper end of said recess, a bimetallic electro-thermally responsive strip adjustably supported at each end within said recess adjacent the opposite side wall thereof, a latch member rigidly attached to the upper surface of said strip between the points of support of the latter, a metal bracket supported above said strip in a predetermined space relationship thereto, a molded insulating block located within said recess and slidable relatively to said bracket, said bracket having a slot extending longitudinally thereof, a second latch member associated with said block and having a portion penetrating said slot for interlocking engagement with said first mentioned latch member under normal conditions upon movement of said block to one extreme position, spring means associated with said block to normally bias the same to its opposite extreme position, said block having a relatively large notch formed in the upper surface thereof, and a manually operable lever pivotally supported above said base, said lever having lateral projections at the lower end thereof to respectively fit within the aforementioned notches, the notch in said block being adapted to afiord clearance for the projection associated therewith upon movement of said lever to effect circuit interrupting operation of said switch after initial movement of said lever to effect circuit completing operation of said switch with coincident engagement of said latch members with each other, the aforementioned spring means acting upon disengagement of said first mentioned latch member from the second latch member as an incident to a predetermined overload condition to eiiect automatic circuit interrupting operation of said switch, and said lever when manually held in one extreme position thereof counteracting the spring bias of said block, to thereby maintain said switch in circuit completing position notwithstanding operating response of said strip to a predetermined degree of overload in the controlled circuit.

18. In an electro-thermally responsive overload circuit breaker, in combination, a snap switch mechanism normally adapted for movement to and resilient retention in either its circuit completing or its circuit interrupting position, a pivoted manually operable lever for effecting such movements of said switch, a molded insulating block positioned at one side of said switch and also movable by said lever to one extreme position 'upon initial movement of said switch to circuit complet ng position, means comprising a pair of coiled compression springs interposed between said block and a suitable abutment to bias said lever, and consequently said switch, to circuit interrupting position, one of said springs being adapted to nest within the other, and the co ls of said springs being mud in opposite directions respectively to insure against interweaving thereof when in use, a latch member associated with said block, an lectro-thermally responsive bimetallic strip positioned beneath said block and having a latch member rigidly attached thereto for cooperation with the latch member first mentioned, a wiring terminal member associated with th stationary contact of said switch, a plurality of multiple-strand wire bus members affording a flexible electrical connection between the contactor of said switch and said bimetallic strip adjacent one end of the latter, a second wiring terminal member, and a multiple-strand wire bus member affording an electrical connection between the other end of said strip and said last mentioned terminal member.

17. In a high capacity electro-thermally responsive circuit breaker, in combination, a normally flat bimetallic strip adjustably supported at each end for positioning thereof in a predetermined plane, a latch member rigidly attached to the upper surface of said strip at substantially the mid-length thereof, a pair of metal blocks rigidly attached to the lower surface of said strip at points substantially equally spaced from said 2,342,945

20 latchlengthwiseofsaidstrinapairofrelativeiy narrowslots formedinsaidstrip inalinemmt with the sides of the respective blocks adlaoent 'eachother,saidsiotsactingtominimiaethe mally flat bimetallic strip adjustably supported at each end for positioning thereof in a predetermined plane, a latch member rigidly attached to the upper surface of said strip at substantially the mid-length thereof, a pair of metal blocks rigidly attached to the lower surface of said strip at points substantially equally spaced from said latch lengthwise of said strip, a pair of relatively narrow slots formed in said strip in alinement with the sides of the respective blocks adjacent each other, said slotsacting to minimize the transfer of heat from the active portion of said strip to said blocks, means comprising multiple strand wire bus members each having an end thereof rigidly attached to the lower surface of one of said blocks, a switch contactor pivotally supported in planes respectively oil'set laterally from and below said strip, one of the aforementioned bus members having its other end rigidly attached to said contactor adjacent the point of pivotal support thereof, and said last mentioned bus member being divided into at least two groups of multiple strands to increase the flexibility thereof, whereby resistance to oscillatory movement of said contactor is minimized.

- anvm w. mm.

- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 45 Number Name Date 1,213,751 Crossley Jan. 23, 1917 1,271,558 Francis July 9, 1918 1,331,929 Kaufman Feb. 24, 1920 1,596,018 Mueller A118. 17, 1926 Krieger Feb. 29. 1944