US1713559A - Controller - Google Patents

Description

y 1929- J. E. SEDERHOLM CAONTROLLER R 0m 1. TO a 5 NH R ER 4 V5 m N. D 1.5. s 5 5 E N 7 7 H m .TAW 9 4 w m F d 1 m May 2 1929.

J. E. SEDERHOLM CONTROLLER Filed Feb. 9, 1927 5 Sheets-Sheet 2 v r-"; '93- v l k 7 i I 80 90 I Z INVENTOR JOHN E. SEDERHOLM 'FiT-ronnsvs May 21, 1929. J. EQ-S-EDERHOLM CONTROLLER Filed Feb. 9, 1927 53heets-Sheet 3 INVENTOR JOHN E. SEDERHOLM HTTORNEYS May 92.9. -J. E. SEDERHOLM CONTROLLER 5 Sheets-Sheet 5 Filed Feb. 9, 1927 1' N VEN TOE JOHN E. SEDERHOLM HT-roRNEys Patented May 21, 1929.

UNITED STATES PATENT OFFICE.

JOHNE. SEDERHOLM, OF ST. PAUL, MINNESOTA, ASSIGNOR TO THE AMERICAN 'HOIST 6:7 DERRICK (19., A PARTNERSHIP COMPOFEED OF F. J. JOHNSON AND W. O. WASH- BURN, OF ST. PAUL, MINNESOTA.

CONTROLLER.

Application filed February 9, 1921. Serial No. 166,984.

This invention relates to improvements in motor controlling switch providing a primary or main line switch which operates instantaneously when manually operated, along with a secondary switch, both sw'tches being controlled by a single lever, and operable in a manner to cause a quick make and break of the primary switch, the circuit raking movement of said primary switch being made before thesecondary switch closes its circuit.

An object is to provide an improved arrangement of contacts for a seconda y switch element, in which contact lingers embrace the members of rows of posts, during the resistance cutout or cut-in operations, the lingers engaging in direction of the rows, and the corresponding members of the rows being aligned transversely to the direction of movement of the lingers to obtain a staggered arrangement.

Other objects of my invention are to eliminate or reduce the amount of arcing at points of contact; to eliminate small screws in the contact path, which when used are frequently burned or welded over, and are very dililcult to remove, when it is desired to re new the parts to provide a primary or main line switch. that operates instantaneously when-manually operated thus avoiding burning of the contacts; to provide a controller where all parts including the contacts are mounted. on one panel thus making it possible to renew the entire contact mechanism or any portion thereof very quickly; to simplify the general construction; to provide a compact. arrangement of the elements Features of the invention include, all details of construction, as well as spatial relation of the primary and secondary switch elements; the construction for rocking and reciprocating the switch elements. by means of a single pivoted lever, including also the manner of pivoting said lever, intermediately.

Advantages will be set forth in the descriptionof the drawings forming a part of this application, and in said drawings:

Figure l. is front elevation with the box cover removed and showing the parts in neutral or open circuit position;

Figure 2 is a view similar to Figure 1 showing the parts positioned, as when circuit is being made through the switch;

F i 'ure 7 is a vertical section substantiallv on line 1-4 or F igure 3 illustrating the mounting of the spring fingers.

Figure 8 is a plan section on line 8-8 of Figure 3 illustrating the mounting of the switch arms, with the arm in switch-closed position; and

Figure 9 is a diagrammatic view illustrating a use of the device.

A rectangular casing is shown at 1 and is provided with front and rear covers respectiv'ely 2 and 3. Interiorly the casing is pro vided with vertically aligned top and bottom flanges respectively t and 5, bridging and a tached to which is a base f sheet insulating material. This base supports all the working parts of the apparatus, and the piece is removably secured as by bolts 7.

Upon the base a carrier or slide is translatably mounted. This mounting consists of a pair of spaced tracks orguides 10 suitably secured atopposite endsas by screws or bolts 11. These tracks are arranged in parallel relation and are adapted to support the carrier in this instance for vertical movement. The carrier is generally indicated at 15 and is provided with grooved vertical extensions 16 as slides, the grooves of which engage the guides 10 as best shown in Figure '4'. Coiled sprii :20 are arranged beneath the carrier to urge the same upwardly in direction of spaced rows of contact posts 18, the carrier having fingers or contacts engageable with these posts in a manner to be described.

The arrangement and connection of the fingers upon the carrier are features of this invention. It will be noted that the fingers-extend in direction of the reciprocation of the carriage 15 and that the fingers are spaced in a direct-ion longitudinally of the carriage and transversely between the guides 10. The carriage 15 may be considered as a base, having what may be considered raised abutments or projections 30, see Figure 7, flanked by extensions 3182, theext ensions 31 being aligned in direction lengthwise oi the base or carrier 15. 'The extensions 31 are short, while the en tension 32 is of a length substantially equal to that of the carrier. These plate-like extensions provide means for preventing lateral tipping of the fingers or arms, which are disposed in pairs and opposingly arranged one at'each opposite side or the projection as est shown in Figure 7 and have their edge surfaces slidable between the extensions. Means yieldably connecting each element directly above the projection are provided. Each means consists of a bolt 35 loos-ely'traversing both arms.v Surrounding the bolt is a coil spring 36 abutting one oi? the fingers 40 i at the outer side, and at the other end abutting astop formed by a washer ll held against translation by apin 42 end of the bolt is secured against translation The opposite by a pin'4l5 engaging at the outer side of the opposite finger. Theelements 3132 as beforestated-prevent lateral tipping, and act as guides between which theiingers are secured in upright position, with their outer terminal portionsspaced. A pin iti as means to prevent upward movement or the lingers is shown at 4:7 and said pin traverses the extensions 3-l'82. This pin lies directly above the pin or bolt 35 and in such a position as to pre- 3 vent such upward movement of the fingers'as vwould disengage thesa-me from the projection 30. However, when the linger-s are worn as a result tor example of arcing any set can be (IL'UClKlYTBIDOVGfil by removing thepm 46 and pulling upwardly. This construction provides a means whereby replacement can be easily and quickly made without dismantling any part the apparatus with the exception of the disengagement oi' thepin as. Thefingers are assembled in pairsand when it is desired to place them, they are simply separated sufficiently to engage the projection 30 and allowed to spring backto'frictional engagement at opposite sides of said projection or abutment. V

- In combination with the translatable carrier having the contact elements or fingers 40, a rockable switch-arm is provided, which is adapted to be tipped by a lever which is also associated through a link with the translat-able carrier. 7 V

c This rockable switch arm or device forms a feature of this invention and provides a knock-down construction composed oi renewable parts, which can be quickly and easily attached or detached for purposes of assembly or replacement. V

This device provides a pair of switch arms 49, see Figure each independently rockably mounted and insulated. Standards 50 one for each arm are mounted in opposing rela .tion and eachofthese standards has a pin 51,

being axially alined.

said pins extending toward one another and V The pins are secured in this instance by threads and may be quickly removed. Each standard is secured to the insulating base by a bolt 52, and abolt-like binding post, see Figure 8. V l

Each arm is medially bent asshown in Figures 5 and 8,the bend being in a direction away from the base 6, and lying substantially at the pivotal point oi the arm. Upon that side or the arm adjacent the base, one at each opposite end oi the arm are knife blade *P1O]6C- 'tions 55 ada ated res eotivel and alternatel J to engage contacts 56 secured bybinding I samedegree as the arms, the object oi 'this bend being .to provide means whereby when the end of the lever 20 enga es at the bend '2' b portion both blades 55 will be disengaged flOIIllllGll contacts, thus disposing the switch arms in neutral position, in which neither blade 55 engages a contact. 7,

lVhen it is desired to renewone of the switch arms 49, the plate and insulating blocks as a unit islii'tedto disengage the blocks 61 from the sockets, after-which either arm can be translated inwardly. to disengage the same from its pivot pin 51. Shields (35 are arranged substantially as shown;

A. lcver'm is pivoted as at H K 1 on a, bracket 7 and has its opposite arms respectively overlying the carrier and the rockable re versiug switch device. As shown in Figure 1 the arrangement is suchthat when the lever occupies a inidposition the'contact fingers ol the carrier and the blades of the switch arms l9 are all disengaged frointheir contacts. Moreover, the arrangen'ient issuch that the reversing switch is always brought to one contact positiombefore the carrier fingers engage any of their contacts. Moreover, the lever is arranged for translating the car- .rier; in opposition directions when correspondingly swung, and the arrangement is such that when the lever is in midposition the carrier fingers are always disengagedjtrom their contacts.

That arm of the lever 70 which overlies the reversing switch or rockable switch arm has translatably mounted therein a pin 7 having a button 76 frictionally engaging the plate 62, and slidable therealong to tip the arms or switch levers to opposite switch closed positions, when the lever is swung from the bend or midpoint of the el'e'inent 62 in opposite directions. A spring 75 engages the button to urge it in the direction of the plate 62. As a result of the swinging motion of the lever the rockable switch'is alternately tipped and forced to. opposite switch closed positions, the reversing action taking place while the contact fingers-4O are disengaged from the terminal contact members 18. In this instance it is the short arm of the lever which engages the plate 62. l

The opposite or handle end of the lever is connected for translating the carrier. This connection comprises a slotted leverlike elemeat 80 pivoted to swing, in this case, in front of and adjacent the carrier. The element is adapted to swing generally in direction of reciprocation of the carrier and is connected to the carrier by a link 81, pivoted as at 8283 respectively to the link and car rier, the connection with the carrier being substantially centrally thereof. The element 80 is provided with an irregularly shaped slot, and the lever is connected to the element 80 by means of a sleeve-like roller 85 rotatable upon a stud 86 carried by the lever 70, see Figure 3. The roller rides in the slot to swing the slotted element and correspondingly translate the carrier. Thus the lever has one arm slidably connected with the slotted element. The opposite ends of the slot of the link form stops to limit lever movement in opposite directions. The arrangement and configuration of the different portions of the slot issuch that the contact fingers engage their contacts whenever the lever is swung to opposite limits.

As herein shown, the portions of the slot are arranged at angles to one another, both being curved. As the lever travels from its position shown in Figure 2. to the left the carrier will be lowered, and when the roller reaches the point 90 the fingers 40 will all be disengaged from the contacts as shown in Figure 1. At this stage the lever is in its mid-position, and the reversing switch is open or in neutral position. Upon continued movement in the same direction through that portion of the s ot designated 91, the link 80 will be raised to again assume substantially the same position as shown in Figure 2. This posi tion of the lever being shown in dotted lines at the left of the figure. In both positions of the lever indicated in Figure 2, the reversing switch is making contact.

The handle of the lever 70 has a detent 96 engageable with notches 97 corresponding to the number of posts 18, in this instance, 9 on each side of the center line of the apparatus.

Another feature of the invention is the ar rangement of the contact posts 18. These contact elements are arranged in rows, the members of each row being alined in direction of the reciprocation of the carrier. The members of the second row have a staggered relation With those of the first, and the members of the third row have a staggered relation to the members of the second row. The rows and the members of the rows are so related that the spring fingers successively engage the first member of respective rows in sequence, the last pair of fingers engaging the first member of the last row before the first pairof fingers engage the second member of the first row, the action being continuous in this manner and in the same direction, until the last pair of fingers engages the last member of the last row, at which time each finger is engaged with'a contact. As shown in Figure 6 the first members of all rows are alined in a row extending transversely to the direction of movement of the carrier. However, this row is not perpendicular to the path of the carrier, but forms an acute angle with a line which is perpendicular to the translative path of said carrier. The second niembers of all rows are alined in a similar manner as are also the third members, the lines re resenting the alinementbeing substantially parallel. This arrangement provides the staggered relation above re ferred to.

The electrical connections are so made and the arrangement of the posts 18 is such, that at full speed position of the device shown in Figure 2, all resistances are cut out. This is true for either full speed ahead or full speed reverse, the position of the lever 70 for these speeds being respectively shown in dotted andfull lines in the figure.

It will be further noted that there are always four simultaneous contacts between the spring fingers, and the posts to keep the phases always closed.

,The motor controller has herein been shown to be particularly designed for alternating current, and the device provides a quick make and break primary switch, while the secondary contact construction much simplified. The present invention eliminates the use of leaf springs for contact fingers, which are easily broken as the result of overstrain and crystallization. The present device also provides a control lever which has aswinging motion in a vertical plane, as distinguished fromthe old types of controller which have a rotary motion, in a horizontal plane.

In Figure 9 the device in diagrannnatically shown as connected to a three phase slip ring type of motor. The stator is indicated at 100 and the collector rings are respectively indicated 101, 102, 103. Main line wires are respectively indicated at A, B, G. The binding posts 5758 are cross connected in pairs respectively by connections 105106. Connect-ions from the binding posts 53 ot the switch arm supports, are connected with the stator 100 respectively by wires 108-109 and the stator is additionally connected with the main line Wire G by Wire 110. Binding posts the carriage 15, fingers F engage post 117, and resistance between 126-127 is cut out,

of time per day.

quick make and break type, this quick make and break feature being necessary in a controller where the circuit is broken thousands In Figure 9 the switch arms may be considered as in a position corresponding to forward rotation of the motor. In this position the arms '49 are in contact with their respective posts 57. In this position the current flows from'line B through 112, 58, 105, 57, 49, 53, 109, 111,108,49, 56, 1.06, 58,114 to line A. 1 After the primary switch has been closed as above; described either for forward or reverse motor rotation, the secondary-switch is then operated as a result of the continued swing of the lever in the same direction. This lever has the detent 96 engageable in the notches 97, see Figure 1. The reversing switchis brought to contact position while the lever travels from the central notch, to the first notch, in-either direction. During this movement, however, none of the fingers 4O (D EF of the diagram) come in con-. tact with the posts 18, all of the induced current at, this time passing through theresistance connecting bar 125, see upper right portion of F igure 9. In other. words, all the resistance is still in circuit. During the movement of the detent from the first to the second notch, however, and by the time the detent has reached the second notch, fingers D and E have moved into contact respectively with posts 115, 116, that is into the first two members of the first or lower transverse row, cutting out the resistance between 134135 and 133-132. The current then takes the following path: from collector ring 101, wire 138, to post137, through resistance to post 135, through conductor 145, to post 115, through finger'D, bar 15, finger E, post 116, conductor 146, to post 132, to post 130, to ring 102, thus completing the circuit for one phase. v

' In like manner, on continued movement of the post 117 being connected with 127 through wire 147. Whenfingers D engage post 118, of the second transverse row, this post being connected by wire 148 with point 136, resistance between 135-136 is cut out. I/Vhen fingers E make contact with post 119 which is connected through wire 149 with point 131, resistance between points 132-131 is cut out. When fingers make contact withpost 120, which is connected by wire 150 with point 128, resistance 127128 is cutout. WVhenfingers D make contact with post 121, of the third transverse row which is connected by wire 151 with point 137, resistance be tween points 136137 iscut out. When fingers E engage post 122, which is connected by wire 152with point 130, resistance between points 131 and 130 is cut out, and finally when fingers F engage post 123, which is connected by wire 153 with point 129, resistance be tween 128 and 129 is cut out, and thus all resistance is out. i

During reverse movement of the carrier 15 the resistances are cut in, in reverse order.

I claim as my invention:

1. A base, a carrier translatable thereon,

having a contact element, a contact upon the base engageable by said contact element as the carrier is translated, a lever having one arm connected for translating the carrier when i swung, and a rockable switch arm adapted to be tipped alternately in opposite directions by the opposite armof thelever when the lever is correspondingly rocked.

2. A base, a carrier translatable thereon having a contact element, a contact upon the base .en 'a eable b said carrier contact element the carrier is translated, a lever having one arm connected for translating the carrier in opposite direction when correspondingly swung, and a rockable switch arm adapted to be tipped bythe opposite arm of the lever to opposite switch closed positions, when the lever is swung, and'passes from a mid-point in opposite directions.

3. A base, a carrier translatable thereon having a contact element, a'contact upon the base en 'a 'eable b the element as the carrieris translated, a lever connected for translating the carrier in opposite directions when correspondingly rocked, a rockably mounted switch arm operable by the lever to be alternately rocked to switch contact positions, the

reversing action taking place while the contact finger is disengaged from the terminal contact. i

4. A base, a translatable carrier thereon having a contact element, a series of terminal contacts upon the base successively engageable by the elemnt as the carrier is translated, a lever connected for translating the' carrier. when swung, and a rockable switch operable by the lever to be alternately tipped and forced to opposite switch closed posit-ions.

5. A base, a translatable carrier thereon having a contact element, a series of terminal contacts upon the base successively engage-able by the element as the carrier is transgageableby the element as the carrier is trans nal contacts upon the base successively enlated, a lever connected fortranslating the carrier in opposite directions when correspondingly svung, a rockable reversing switch operable by the lever to be alternately forced to reversing switch contact positions, the reversing action taking place while the contact linger is disengaged from the terminal contact, and a spring urging the carrier in direction of the contacts said lever being 7 arranged and connected to torce the carrier against the action of the spring, said connections being such that the contact element is disengaged troin all contacts when the lever is at an intermediate point in its swinging are.

7. An element rockably mounted a reversing switch arm, having switch blades, contacts alternately engaged by said switch blades, a lever having an arm slidable against said rockable arm, said rockable arm being so coniigurated that when said lever assumes one nid position both blades are disengaged from their cont cts, and so that as the lever arm is swung n opposite directions the blades are correspondingly enga ed with and disengaged from their (fOlibilCLS.

'8. An insulating base,'a carrier slidable thereon, a plurality oi pairs of spring fingers mounted on said carrier, a plurality of rows of contacts, the members of each row alined in direction or the reciprocation of the carrier, the members being spaced for successive engagement by corresponding spring arms as the carrier is translated, the rows being so relatedthat the spring fingers successively enthe lirstinembers of respective rows in sequence, the last pair of fingers engaging the first member of the lastrow before'the first pair of fingers engage the second member of the first row, the action being continuous in this manner until the last pair of tin- .gers engage the last member of the last row.

9; A device of the class described including an insulating base having a carrier translatably mounted thereon, aswitch element upon the carrier, a contact engageable by the element as the arrier is translated, springs urging the carrier toward'the contact, a slotted element pivoted to swing adjacent and con nected to translate the carrier, generally in a direction of its translation, a rockable reversing switch arm having blades, contacts alternately engageable by said blades as the arm is rocked, the arrangement being such 'that both contacts are disengaged when the rockable element is in an intermediate position, a pivoted lever having one arm slidably connected with the slotted element and having its other arm slidable against the rock able switch arm, the arrangement being such that when the lever is at an intermediate position the rockable element is disengaged from both contacts and the carrier switch element is disengaged from its contact, the

rier is at the same translative limit, when the lever is at one of its lnnns ot motion, the

said linlr element forn'iing a stop for the lever in opposite directions.

10. A device of the class described comprising a carrier translatably mounted, a switcn element upon the carrier, a contae enga 'eable by the element as the carrier is translated, a slotted element pivoted to swing 'enerally in the direction of the carrier translation, and connected to translate the carrier, a reel-(able reversing switch arm having blades, contacts alternately engageable by said blades as the arm is rocked, a pivoted lever having one arm connected to ride in the slot of said slotted element, and having its other arm slidable against the rockable switch arm, the arrangement being such that the carrier is at the same'translative limit when the lever is at either of its limits of motion.

11. A device. of the class described comprising a carrier translatably-mounted, a switch element upon the carrier, a contact engageable by the element as the carrier is translated, an element pivoted to swing and having a slot, said element connected to translate the carrier, at rockable switch arm, contacts alternately engageable by said arm as the switch isroclred, a pivoted lever having one arm connected to ride in the slot of the slotted element and having its other arm engag ig the rockable switch arm, the arrangement being such that the carrier is at one translative limit when the lever is at one of its limits of motion, and the arrangement further-being such that all switches are open when the lever assumes one intermediate position.

12. A device of the class described comprising a carrier translatiblv mounted, a switclrelement upon the carrier, a contact engageable by the element as the carrier is translated, an element pivoted toswing and having an irregular slot and connected to translate the carrier, a roclrable switch arm having cont-acts altcrnatelv engageable by nately cngagcable by said blades to close the circuit. a lever having one arm slidahly connected inthe slot of the slotted element icuit through one contact when the lever occupies any" but a mid-position, the connections between the slotted element and the lever being such that when in this mid-position the contact arm is disengaged from its contact,and' the, arrangement and configuracontactwhen the lever isswung to opposite tion oftheslotof said swinging element be mg such that the contact arm engages the limits, said swinging element having a link connection witlrsaid carr1er..

'gers opposingly arranged one against each opposite side oi said pro ect10n, means yieldably connecting said elements directly above the projection, means for preventing lateral tipping of the fingers or arms and a stop lylng between the arms and above said yield able connecting means to movement thereof. 7 V g 15. A device otthe class" described comprising acarrier slidablymounted having a contact finger, contact engageable'by the finger when the carrier is translated, a link slidable against therockable elements to open both contacts when the lever occupies a midpivoted to swing, a rockable arm having blades, j contacts. alternately engageable by said blades to close a; plurality of circuits, a

clever having one arm 'slidably connected to the swingable link and having its other arm position, the connectionsbeing such that the carrier contact fingers only engage their conftacts as the lever is swung to opposite limits V gers engaging against opposite sides ofthe, PI'OJGClZlOIl, a lJOlt'tIELVBI'SlIlg the armsabove.

from a mid-position, said swinging link element having a linkfconnection with the carriage. .7

16; A base having a raised projection, fined with an insulating element, said insulating element removably socketed in said arms. I r 18.. A pair of'arms each rockably mounted.

on a separate pivot,said pivots axially alined -1I1 a d1rect1on transverse to the arms, each 'armbeing only removable from its pivot in a direction toward the other arm, and each aim being bent intermediately in a direction away from itsmounting, and a plate similarly bent and havingits oppositeends con-, nectcd with insulating element, said element being socketed in said arms.

' 19. A pair of arms independently rockably mounted, and a plate bent intermediately in direction away fromthe mounting of the prevent upward arms said late havin insulatin elements and said elements beingdetachably socketed in said arms.

20. A pair otswitch arms, a mounting for each arm havinga pivot upon which the arm is rockably supported and axially slidable for removal only in a direction toward ,theother arm and a plate iliaving each opposite end connected'to an insulating element, said elements being removably socketed in the arms I 75 lots, and to provide means by which the arms v are rocked. V 14. A base having a raisedprojection, finto prevent sliding-of the arms on their pivoted to the base,'a switch arm arranged be-,

neath one arm of tee lever-and rockably pivoted on an axis perpendicular to the pivotal 7 axis ofthe lever, said lever arm having contact yieldably urged and slidable against directions asthe lever is correspondingly same direction as the pivotal axislot the rockthe switch arm tov rock the samein opposite able switch arm, andiarranged beneath the. 7'

other arm of the lever and having contact fingers,'contacts engageable by the fingers when the carrier istranslated,'means yield- 7 ably urging the carriertoward the contacts a link having one end pivoted laterally of.

being curved in opposite directions and meet- 7 ing at a point medially oi the link. means connecting thelast mentioned lever arm, Wlllll the link slot toiswingthe link and a second link connecting the slotted link tothe carrier, the connections being such that when thelever is in a mid position the carrier is in fully retracted position with its fingersdis- "engaged from the contacts, and the rockable switch arm is in non-contacting position, V 22(A pa1rofsw1tch arms each independentlyrockably mounted and insulated and r having a binding post, cont'acts tor each arm alsoiinsulated and having binding posts and alternately engageable by; corresponding arms, insulating blocks removably socketed 111 said arms at opposite sides of their pivots, and V plateconnecting with andv only engaging said blocks said plate-being medially. bent in-a direction away from the arms, and having the bend located substantially the axis of rotation' of thearms 23. A base, a carrier:translatablethereon havinga series 'ofp'airs ofcontact fingers, rows of spaced-contact elementsalinedin direction of reciprocation of the carrier, members of thesecond row being staggered in relation to corresponding elements of the first, in a direction transversely to that of carriage reciprocation in such manner that the fingers of the second row engage the first responding members of the rows being alined in direction transverse and at an angle to the direction of parallelism of the rows, a series of contact fingers arranged for translation to V successively contact the first members of the parallel rows when translated in direction of parallelism of the rows, the transverse alinement of the posts being such that the fingers successively engage the first members of respective rows, such that the finger of the first row only engages the second post of the first row, after the last finger has engaged the first finger of the last row.

25. A device of the class described including a rockable switch element having contacts alternately engageable when rocked in corresponding directions, a second element translatably mounted and having contact fingers, contacts engageable by said fingers as the element is translated, a lever having a link connection with the translatable element, I

and also having a sliding connection with the roekable element.

26. A device of the class described including a pivoted switch element having contacts alternately engageable when rocked in corresponding directions, a carriage translatable toward and away from the rockable switch element in a direction parallel with taneously rock the pivoted switch element and translate the carriage.

27. A device of the class described including a pivoted switch element having contacts alternately engageable when rocked in corresponding directions, a carriage translatable toward and away from the rockable switch element in a direction parallel with its pivotal axis, and having contact fingers, contacts engageable by said fingers, and a lever arranged and connected to simultaneously rock the pivoted switch element and translate the carriage, the arrangement being such that the pivoted element is rocked to a controlling position before the carriage contact fingers engage their contacts. v

28. A pair of independently rock-ably mounted switch arms, said arms only removable from their mountings in adirection toward one another, and an insulating element removably connected to the arms to prevent their disengagement from the mountings, and an element connecting the blocks and extending in a direction lengthwise of the arms and at an angle to the rockable axes of the arms. A

29. A base, a secondary switch comprising a carriertranslatable upon the base and having a contact element, a contact upon the base engageable by said element as the carrier is translated, a lever connected for translating the carrier when swung, and a rock-able primary switch adapted to be tipped by the lever when the lever is rocked.

In witness whereof, I have hereunto set my hand this 5th day of February, 1927.

JOHN E. SEDERHOLM.

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