US2447320A - Electrical switch - Google Patents

Description

Au8 17, 1948 s. M. l. DE OLARIAGA ETAT. 2,447,320

' ELECTRICAL swITcH Filed July 17, 1947 3 Sheets-Shea?. 1

INVENTORS ATTORNEYS Aug. 17, 1948. s. M. l. DE OLARIAGA ETAL 2,447,320

ELEcRrcAL swITcH Filed July 17. 1947 s shane-smet 2 INVENTORS 511.11 aba/zwem de O La/zw' a/ al@ @fzln/1L Aug' 17, 1948 s. M. l. DE OLARIAGA ErAL 2,447,320

ELECTRICAL SWITCH 3 Sheets-Sheet 3 Filed July 17, 1947 Patented ug. 17, 1948 ELECTRICAL SWITCH Sara Maria Iribarren de Olaraga, Luis Bulgarini, and Percy-Forster, Buenos Aires, Argentina Appiieation'auly 17, 1947,'seria1Ne. 761,542

` In Argentina May 22, 1947 Claims. 1

This invention relates to an electrical switch of simple and durable construction, and highly reliable in operation.

One of the objects of the present invention is to provide an electrical switch having the desirable characteristics of rapidly closing and opening the circuit, thus avoiding bad connections and arcingat the contacts.

Another object is to provide a switch in which the contact bridge, when in the inoperative position, is positively incapable of accidentally establishing contact with the associated resilient con- -tact members, owing to the fact that it is firmly maintained in a definite inoperative position, and in addition, the points of engagement between said contactmembers and the contact bridge are so arranged that electrical `contact between them is impossible.

The new electrical switchincludes two resilient conducting 'arms arranged .in pincer fashion and adapted to retain inits operative position a movable :bridging conductive member, represented by a ball, roller or thelike, capable of passing from the operative 'to the inoperative position due to the thrust effect of means operated from the outside and 'under the resilient action of said electrical conducting meansy the switch according to this invention being further characterized -by the fact that the two conducting -arms arranged in pincer fashion have curved portions inter-mediateof their length, adapted to cooperatively receive and retain the movable bridging member, one vof the pincer arms being provided with an end extension that vcontinues from the associated curved portion and is so shaped as vto facilitate the release and the entrance of the bridging member, while the-other res'ilient'pncer arm Vhas a bent resilient-extension the free end of which -is arranged at such a distance tothe nearest 'part'ofthe curved seating portion of the same arm, 'that the movable bridge is capable of moving from said curved portion to the free end without 4breaking contact with the conducting arm, an insulating shoe being mounted on the above mentioned free end of the bent resilient extension and'which, when the Contact bridge is in operative position, remains normally interposed `between vthe conducting portions of the related arm and the other 'conducting arm, thus irripeding the access of the contact bridge to the conductive lpincer, said shoe having in addition a contact edge vor face opposite to a corresponding portion of the other member, to form with said portion, a resilient impulsion eouplewhich tends to force the contact bridge Atowards the inside of the pincer, during the operative stroke of said bridge.

Other objects 'and advantages `of the invention will become apparent to those skilled inthe art, from the following description taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention fand wherein:

Fig. l is an external perspective View of a single-pole wall switch.

Fig. `2 Vis another perspective but of a 'section-of thesame switch of Fig. 1, the Contact Ybridge being in its operative position, between Vthearrns of the pincer.

Fig. 3 is a lateral elevation and longitudinal section of the same switch, the'contactbridge be.- ing shown still in its operative position ibetween the arms of the .pincen but .just about'to be ejected from the arms of the pincel?, in order to open the circuit.

I`Fig. 4 is similar to Fig. 3, but in which 'the movable contact bridge is in its inoperative posi.- ti'on, and makes contact with only one of the conducting portons of the resilientarms of the'pincer, so that 'the circuit in which the switch is interposed will lremain open.

Fig. l5 is a perspective View of `a three-pole switch, in which, to simplify the drawing, some parts have been eliminated, for instance the cover and the main base.

Fig. '6 is a side elevation and sectional View of a switch of the type of Fietb7 but without eliminating'the above mentioned parts.

lThe same reference characters are used 'to in.- dicate like or corresponding parts or elements throughout'the drawings.

In accordance with that illustrated in Figs. 1 to 4, corresponding to a single-pole switch, a is an external box in the shape of a prism having irregular hexagonal bases which are indicated with the numerals l, I. 'One of the side faces is removable for access to the interior of the switch, while the largest side 2 constitutes the front of the box. When the box is embedded in theca'vity of a wall, the sides 3 and 'l of the same box form respectively the upper and lower base. The remaining sides, 4, 5 and 6 form the back Wall v.ofthe box. The holes 8, formed in the front -2 and walls 4 and 6, are used for attaching Vthe box, 4and 'consequently the switch, tothe corresponding wall cavity, in which the usual metal fittings must be provided forthe mounting screws adapted tofgrip the box a through the holes 8.

The construction of the outer box a is completed with a rectangular window 9, formed .in the front wall 2 and adapted, as will be shown later, to receive the operating handle of the switch.

Within the bor: a is provided a movable body b generally shaped as a 'prism of hexagonal base, similar to a, but smaller and without the bases that would correspond to the surfaces I and I' of the box a. As rmay be seen in Figs 2 to 4, the inner movable body b, which has a front I0, two bases Il and l2 and three rear faces I3, 'I4 and be displaced within the box by means of the r handle l 6 projecting out of the box a thro-ugh the window 9. It should be understood that the window 9 must preferably be of such dimensions as to provide only suiiicient space for the passage and necessary movement of said handle, thus serving as a guide and movement limiting means for said handle. Thus, it will be also observed that the outer box a being only opened at its window portion 9, and the front l) being applied directly against the inner face 2 of the box a, the interior of the switch, and consequently all the inside elements will be protected from dust.

-1 The side wall l of the box a is provided with two interiorly projecting supports Il and I8 which are disposed within the movable body b. On these supports there are fixed by means of the corresponding screws l 9 the resilient arms c and d arranged face to face, as shown in Figs. 2, 3, and Zi. The conducting wires e may also be affixed to these screws. The two resilient arms are made of metal sheet having a high electrical conductivity and are shaped according to the interrupted sinusoidal form as illustrated, both having curved intermediate portions 20 and 2l, so dimensioned as to form cooperating retaining seats for the movable bridging member f, also made of conducting material. This member is represented as a cylinder, although it will be apparent that it may be in the form of a spherical ball or any other body having a suitably curved surface. The movable member f has as lateral guides the walls l and I of the boi.r a, spaced apart at a distance slightly greater than the length of said member. The two above mentioned resilient arms, due to their constructive and operational characteristics, constitute a form of retaining pincer for the bridging member f. Beyond its curved seat portion 2l, the arm d is provided with a slightly curved short extension 22, adapted to serve as a point for the ejection or entrance of the roller constituting the movable contact bridge.

Referring now to the resilient arm c this is also provided with an extension formed beyond the intermediate seat portion 20. Unlike the arm d, the end extension 23 of the arm c is bent in the form of a U, the two legs of which face towards the other resilient arm. The leg 23', which is the farthest spaced from the intermediate curved seat 20 is located at such a ydistance from such seat that the roller f when being displaced towards said leg 23 engages said leg before leaving its seat, whereby the continuity of connection between the two arms is not interrupted. The leg 23' is so proportioned and disposed that its free end, which may be provided with a slightly widened portion 23" in order to offer a greater contact surface to the roller f, faces the extension 22 of the'arm d, and is spaced at such a distance from the extension 22 of the arm d that the roller fis gripped in a pincer-like fashion when moving from the extreme operative position of Fig. 2 to the intermediate position of Fig. 3.

In the free leg 23 of the U-shaped bend 23 which also includes the slightly widened portion 23, there is loosely mounted an insulating shoe g, which has an arm 24 terminating in a bend 22', which, as shown in Fig. 2, cooperates with the leg of the U-shape-d bend located immediately beyond the seat 20 of the arm c. In this way, the

4 bend 2t partially surrounds the aforementioned leg of the arm c in order to limit indirectly the movements of the other ypreviously mentioned leg 23'; This ensures that the'leg 23 will be always maintained at a minimum distance from the seat 20, thus providing for the electrical continuity of the connection between the arms c and d when the roller f moves away from the seats 2B and 2l. A part of the contour of the shoe g is curve shaped similarly to the outer surface of the roller f, so that it fits firmly over said roller, as shown in Fig. fl. Between the portion 25 and `the leg 23 of the bend 23 is a short straight porthe inoperative position.

tion 26, against which the roller f bears initially when being inserted between the arms c and d of the conducting pincers so that the rolleris held between the non-conducting portion 26 vof the shoe and the end extension 22 of arm d, which; due to its spring tension is capable of snapping the conducting roller into the pincers at the ap-v propriate time.

It will be seen from Figs. 2, 3 and 4, that the switch, as described, is provided with two stops 2l integral with the side wall i 'of box a and adapted to maintain the roller f in its inoperative position, and limiting its spacing from the seats 2b and 2l of the pincers (Fig. 4). There are also provided two otherstops 28 and 28 which are movable and serve as means for moving the roller member employed as the connecting bridge element of the switch. These two stops 28 and 28' are formed in or Jfitted in line with but opposite each other on the interior walls of the inside movable body having been arranged oppositely and on the same line at the side walls b and are positioned so as to engage the bridging roller at two diametrally opposed points, and to pass between the arms of the conducting pincers when moved to and from the extreme positions illustrated in Figs. 2 and 4 respectively. l

From the foregoing, it will be seen that in the embodiment illustrated by Figs. 1 to 4, the movable contactbridge represented by the hollow metal roller, is subject at all times to the action of the conducting arms c and d, arranged in pincer like fashion. The arms do not however, act by themselves, but their action is assisted by the movable stops 28 and 28', which in turn are actuated externally at will by means of the handle The effect, the movable stops 28 and 2W represent the means, controlled by the user of the switch, by which movement of the contact bridge is initiated in order to place it in the operative or These stops, however, are not capable of controlling the moving bridge in the last stage of its displacement, which takes lplace under the action of the arms c and d of the spring pincers and which are completely outside the control of the operator. This detail is of the utmost importance,l since il; ensures the completion of the final part of the displacement of the bridging roller, independently of the operator of the switch, who is therefore prevented from incorrectly operating the bridge and thus causing, either deliberately or accidentally, false contacts when the bridge is introduced or withdrawn from between thearms of the pincers.

Thus, when the bridge f is in the operative position as shown in Fig. 2 in which it is gripped between the two cooperating seats 29 and 2| of the arms c and d for closing the electric circuit of the switch, it is necessary, in order to move the bridge to the inoperative open circuit position as shown in Fig. 4, to.cause the internal 5 movable body b to move downwards by moving the handle I6 in the same direction. The movable stop 28 then advances towards the bridge f and the stop 28' moves away from it as the other stop advances. As the bridge moves away from the seats 20 and 2|, the arms c and d of the resilient pincers open suiiciently to allow of the passage of the bridging roller. During its movement, the latter roller reaches the position shown in Fig. 3, in which position it has practically left the seats in which it was retained, and is actually tightly pressed by the two arms of the pincer; and is just about to be ejected at an even greater distance from said seats. It should be noted that in said intermediate position in which the bridge is still engaging the arms of the pincer, the roller f is also engaging the free end 23 of the U extension of the arm c; i. e., it maintains a double Contact with said arm. rIhis is important since, as the ejection of the roller to the inoperative position of Fig. 4 must occur under the pressure of the free end of the bend 23 and the opposite angular portion of the other arm of the pincer, it is necessary that until said ejection is effected the roller is maintained in contact with both arms of the pincer. If, in passing from its position between the seats 2li and 2| to the position in which it engages the free end of the bend 23, the roller f were to become momentarily disengaged from the arm c (at this stage of its movement, the roller is controllable from outside), it would be possible to produce a slow breaking of the contact between both parts, with the consequent detrimental results.

As soon as the movable stop 28 advances a little farther, the twoparts of the resilient pincer that press rmly on the curved surface of the roller, begin to slip along said surface, in a natural and independent closing movement, due

to spring action, and by pinching the roller,

sharply eject it against the stops 21. This breaks the contact between c and d, and leaves the roller rmly held against the stops 21, on account of the fact that the arms of the pincer continue their movement and close behind the roller. The latter is thus retained between the stops 21, the shoe g and the end extension 22 of the arm d, as shown in Fig. 4. The movable stop 28, however, is made of such a length that it does not advance beyond the position reached when the two arms of the resilient pincer start the pinching action on the roller.

To reclose the circuit, by restoring the bridging roller to the initial position as shown in Fig. 2, the handle I5 is operated in the reverse direction to raise the inner movable body. Thus the movable stop 28 approaches the contact roller, and the stop 28 moves away from it. When the stop 28 engages the roller f and commences to force it between the contact pincers, the arms c and d of said pincer open but maintain contact with the roller, on account of their elasticity. At the initial stage of the movement of the roller, it engages the conducting position 22 of the arm d and the non-conducting shoe o-f the arm c, and thus the two arms are not electrically connected. In yielding to the action of the roller, the shoe moves to the left until its rectilinear contour portion 2G is applied against the curved surface of the roller and the diametrally o-pposed part of the roller is engaged by a portion of the arm d corresponding to its end extension 22 or to the ridge separating said part from the seat 2|. Although the roller makes contact with the portion 26 of the shoe g, it does not enter into contact with the 'free end of the'branch 23 of the bend 23 ofthe arm c. In continuing the movement ofthe stop 28', when the roller f is in a position very similar, although not equal, to that shown in Fig. 3, said roller, without engaging at any moment the free end of the branch 23', is sharply ejected, also by a pinching .action of the two pincer arms, towards the seats 20 and 2| of said pincer, thus producing electrical contact between the two arms, and the resulting closing of the circuit. The resilient arms of the pincer follow the movement of 'the roller and are instantaneously applied at both sides of the roller, the whole assembly assuming the position shown in Fig. 2.

The three-pole switch of Figs. 5 and 6 is essentially a multiplication of the above described single pole switch. The three pairs of resilient arms c' with shoes g and d are substantially similar to the corresponding elements c and d of the other switch and operate in like manner and similar conductor rollers f are also used. The arms c and d' are firmly attached by means of screws 29 against the inner face of the vertical plate 3B. This vplate is in turn attached to the intermediate base plate 3|, which is maintained in a raised position over the principal base 32, by means of the bolts 33. For the external operation of the rollers f' there is provided a sliding member h, made of insulating material and comprising, as may be seen in Fig. 5, a plate 34 with an internal opening 35 which allows of the formation of the movable stops 3S and 3B' adapted to move the respective rollers, and of the large recesses 3? adapted to operate as guides for the plate 34 itself and as means for limiting its displacement. The small vertical stop and guide partitions 38 cooperate with the sliding member h and are adapted to assist in the guiding of the sliding member h, to limit the extent of the movei; ment of said member, and to maintain the bridging rollers f in their lateral position. The sliding member h is provided With a handle 39 attached at its fore end and is arranged horizontally between the arms of the cooperating resilient conducting pincers, being maintained in correct position and free for longitudinal movement by means of two lateral guiding supports 4U attached with screws 4| to the base plate 3|.

The conducting wires e' are connected directly to the terminals 29' (Fig. 6) formed by nuts threaded on to the ends of the screws 29 which are used to attach the arms c and d to the support 3U.

The operation of the three pole switch is substantially similar to the operation of the single pole switch previously described with reference to Figs. 1 to 4, as all the essential elements are practically the same. Thus, when the sliding member h. is moved by pulling the handle 29, the movable stops 35 simultaneously start to move vthe rollers f' away from the seats of the resilient pincers. Each of the rollers is then swiftly ejected in the manner described, above, and remain gripped in the inoperative position (open circuit), between the cooperating stop 36, the conducting end of the arm d and the insulating shoe g'. By moving the insulating sliding member h in the reverse direction, the rollers may be replaced as in the case of the single pole switch to their operative closed circuit positions. In this way, it is possible to obtain a sure and simultaneous opening or closing of the circuit in each one of the three pincer units of the switch.

It will be clear that in carrying the present invention into practice, modications may be made as regards certain details of the construction of the electrical switch described, but always provided that such modifications do not depart from the fundamental principles which are clearly set forth in the accompanying claims.

We claim:

1. An electrical switch including two resilient conductive arms arranged in pincer like fashi-on and adapted to retain in its operative position a movable conductive bridging member represented by a roller, ball or the like capable of passing from the operative to the inoperative position or vice versa by a thrust action of externally actuated means andy by the resilient effect of said electrically conductive arms, wherein the two conductive arms arranged in pincer like fashion are provided at their respective intermediate portions with oppositely curved seating sections, adapted to cooperatively receive and retain the movable bridging member, one of the pincer arms having an end extension that continues from the associated curved portion and is so shaped as to facilitate the release and the entrance of the bridging member, while the other resilient pincer arm has a bent resilient extension the free end of which is arranged at such a distance from the nearest partl of the curved seating portion of the same arm, that the movable bridge is capable of moving from said curved portion to the free end without breaking its contact with the conductive arm, an insulating shoe being mounted on the above mentioned free end of the resilient bent extension and which, when the contact bridge is in operative position, remains normally interposed between the conducting portions of the related arm and the other conductive arm, thus blocking the access of the contact bridge to the conductive pincer, said shoe having in addition a contact zone facing an associated portion of the other member, to form with said portion a resilient pair for impulsion of the contact bridge towards the inside of the pincer, during the operative stroke of said bridge.

2. An electrical switch including two resilient conductive arms arranged in pincer like fashion and adapted to retain in its operative position a movable conductive bridging member represented by a roller, ball or the like capable of passing from the operative to the inoperative position or vice versa by a thrust action effected by -externally actuated means and by the resilient effect of said electrically conductive arms, wherein the two conductive arms arranged in pincer` like fashion are provided at their respective intermediate portions with oppositely curved seating sections, adapted to cooperatively receive and retain the movable bridging member, one of the pincer arms having an end extension that continues from the associated curved section and is so shaped as to facilitate the release and the entrance of the bridging member, While the other resilient pincer arm has an extension bent in the' form of a U with the legs of the U looking facing towards the rst pincer arm and with the free ing arm, thus blocking the access of the contact bridge to the conductive pincer, said shoe having in addition a contact zone facing an associated portion of the other member, to form with said portion a resilient pair for the impulsion of the contact bridge towards the inside of the pincer, during the operative stroke of said bridge.

3. An electrical switch including two resilient conductive arms arranged in pincer like fashion and adapted to retain in its operative position a movable conductive bridging member represented by a roller, ball or the like capable of passing from the operative to the inoperative position or vice versa by the thrust action of externally actuated means and by the resilient eifect of said electrically conductive arms, wherein the two conductive arms arranged in pincer like fashion are provided at their respective intermediate portions with oppositely curved seating portions, adapted to cooperatively receive and retain the movable bridging member, one of the pincer arms having an end extension that continues from the associated curved portion and is so shaped as to facilitate the release and the entrance of the bridging member, while the other resilient pincer arm has a bent resilient extension, the free end of which is arranged at such a distance from the nearest part of the curved seating portion of the same arm that the movable bridge is .capable of moving past said curved portion of the free end Iwithout breaking contact with the vconductive arm, an insulating shoe being mounted on the above mentioned free end of the resilient bent extension which when the contact bridge is in its operative position, remains normally interposed between the conducting portions of the related arm and the other conductive arm, thus blocking the access of the contact bridge to the conductive pincer, said shoe having a curved portion adapted to engage the curved surface of the contact` bridge, a small, preferably straight, portion being disposed adjacent to said curved portion to form the contact zone and adapted to engage said contact bridge only during the movement of said bridge from the inoperative to the operative position in order to form the resilient pair for the operative impulsion of said bridge.

4. An electrical switch including two resilient conductive arms arranged in pincer like fashion and adapted to retain in its operative position a movable conductive bridging member represented by a roller, ball or the like capable of passing from the operative to the inoperative position or vice versa by the thrust action of externally actuated means and by the resilient effect of said electrically conductive arms, wherein the two conductive arms arranged in pincer like fashion are provided at their respective intermediate portions with oppositely curved seating porti-ons, adapted to cooperatively receive and retain the movable bridging member, one of the pincer arms having an end extension that continues from the associated curved portion and is so shaped as to facilitate the release an-d entrance of the bridging member, while the other resilient pincer arm has a bent resilient extension, the free end of which is arranged at such a distance from the nearest part of the curved seating portion of the same arm, that the movable bridge is capable of moving past said curved portion of the free end without breaking its contact with the conductive arm. an insulating shoe being i'lxedly attached to the branch of the bent portion of the corresponding resilient arm which is more remote from the curved seating portion, and provided with an arm engaging the other branch` of the bent portion for limiting the spacing between said tw'o branches, said shoe being adapted when the contact bridge is in its operative position to remain normally interposed between the conductive portions of the related arm and the other conductive arm, and having in addition a contact zone facing an associated portion of the other member, to Iform with said portion a resilient pair for the impulsion of the contact bridge towards the inside of the pincer, during the operative stroke oi said bridge.

5. An electrical switch including two resilient conductive arms arranged in pincer like fashion and adapted to retain in its operative position a movable conductive bridging member represented by a roller, ball or the like capable of passing from the operative to the inoperative position or vice versa by thev thrust action of externally actuated means and by the resilient effect of said electrically conductive arms, wherein the two conductive arms arranged in pincer like fashion are provided at their respective intermediate portions with oppositely curved seating portions, adapted to cooperatively receive and retain the movable bridging member, one of the pincer arms having an end extension that continues from the associated curved portion and is so shaped as to facilitate the release and entrance of the bridging member, while the other resilient pincer arm has a bent resilient extension the free end of which is arranged at such a distance from the nearest part of the curved seating portion of the same arm, that the movable bridge is capable of moving past said curved portion of the free end without breaking its contact with the conductive arm, an insulated shoe being mounted on the above mentioned free end of the resilient bent extension which when the contact bridge is in the operative position, remains normally inl terposed between the conducting portions or the related arm and the other conductive arm thus blocking the -access f the contact bridge to the conductive pincer, said shoe having in addition a contact zone slightly more protruding than the most advanced portion of the free end of the conductive bent portion of said pincer arm and facing an associated portion of the other member, to form with said portion a resilient pair for the impulsion of the contact bridge towards the inside of the pincer during the `operative stroke of said bridge.

6. An electrical switch including two resilient conductive arms arranged in pincer like fashion and adapted to retain in its operative position a movable Conducting bridging member represented by a roller, ball or the like, said conductive resilient arms being iixed to one of the side walls of an external box having a second side wall substantially parallel to the first mentioned side wall to guide the movable contact bridge and to guide an internal sliding body having movable stops adapted to move said movable bridge in cooperation with the resilient action of said electrically conductive arms either to the operative or to the inoperative position of said body, wherein the two lconductive arms arranged in pincer like fashion are provided at their respective intermediate portions with oppositely curved seating sections, adapted to cooperatively receive and retain the movable bridging member, one of the pincer arms having an end extension that continues from the associated curved portion and is so shaped as to facilitate the release and the entrance of the bridging member, while the other resilient pincer arm has' a bent resilient exten.- sion the free end of which is arranged at such a distance'from the nearest part of' the curved seating portion' of the same arm, that the movable bridge is capable'of moving'from said curved portion to the free end without breaking its con'- tact with the conductivearm, an insulating shoe being mounted on the above mentioned free end of the resilient bent extension and which, when the Contact bridge is in operative position, remains normally interposed between'the conducting portions Iof the related arm and the other conductive arm, thus blocking the access of the contact lbridge to the conductive pincer, said shoe having in addition a contact zone facing an associated portion ofy the other member, to form with said portion a resilient pair for impulsion of the Contact bridge towards the inside of the' pincer, during the operative stroke of said bridge.

7. An electrical switch including two resilient conductive arms arranged in pincer like fashion'` and adapted to retain in its operative position a movable conductive bridging member repre,- sented by a roller, ball or the like capable of pass-l ing from the operative to the inoperative posi,- tion or vice versa, said conductive resilient arms being fixed to lone of the sidewalls of an external box shaped as an orthogonal prismhaving polygonal bases with said bases constituting the sides of the box and one of the side wallsV forming the front of the box, an opening in the front wall adapted to accommodate, and serve as a guide means, for the operating handle of the switch', said handle being xed to the front wall of an internal sliding body having movable stops adapt'- ed to move said movable bridge, in cooperation with the resilient action of said electrically conductive arms, either to the operative or to thev in-` operative position ofV said body, and said front wall of said internal sliding body being slidingly applied against the inner face of the front walll ofthe external box, wherein the arms arranged in pincer like fashion are provided at their respective intermediate portions with oppositely curved seating sections, adapted to cooperatively receive and retain the movable bridging member, one of the pincer arms having an end extension that continues from the asso-` ciated curved portion and is so shaped as tofacilitate the release and the entrance of the bridging member, while the other resilient pincer arm has a bent resilient extension the free end of which is arranged at such a distance from the nearest part of the curved seating portion of the same arm, that the movable bridge is capable of moving from said curved portion to the free end without breaking its contact with the conductivev arm, an insulating shoe being mounted on the above mentioned freev end of the resilient bentr extension and which, whenI the contact bridge is in operative position, remains normally 1nterposed between the conducting portions of the related arm and the other conductive arm, thus blocking the access of the contact bridge to the conductive pincer, said shoe having in additionl contact Zone facingan associated portion of the other member, to form with said portion Va resilient pair forimpulsionof the contact bridge towards the inside of the pincer, during the op`v erative stroke of said bridge.

8. In an electrical switch, a plurality of electrical switching units, each unit including two resilient conductive arms arranged in pincer like' fashion and adapted to retain in its operative position 'a movable conductive two conductive bridging member 11 represented by a roller, ball or the like capable of passing from the operative to the inoperative position or vice versa by the thrust action of opposing projections formed in the cut out portion of a sliding plate adapted to be displaced relatively to said bridges, said cut out portion being provided with pairs of respectively opposed notches adapted to cooperate with small guiding partitions located at the sides of and adapted to guide the respective bridges, wherein the two conductive arms arranged in pincer like fashion of each switching unit are provided at their respective intermediate portions with oppositely curved seating portions, adapted to cooperatively receive and retain the related movable bridging member, one of the pincer arms of each unit having an end extension that continues from the associated curved portion and is so shaped as to facilitate the release and entrance of the bridging member, while the other resilient pincer arm of the same unit has a bent resilient extension the free end of which is arranged at such a distance from the nearest part of the curved seating portion of the same arm, that the movable bridge is capable of moving past said curved portion of the free end without breaking its contact with the conductive arm, an insulating shoe being mounted on the above mentioned free end of the resilient bent extension which when the contact bridge is in its operative position, remains normally interposed between the conducting portions of the related arm and the other conductive arm, thus blocking the access of the contact bridge to the conductive pincer, said shoe having in addition a contact Zone facing an associated portion of the other member, to form with said portion a resilient pair for the impulsion of the contact bridge towards the inside of the pincer, during the operative stroke of said bridge.

9. In an electrical switch, a plurality of electrical switching units, each unit including two resilient conductive arms arranged in pincer like fashion and adapted to retain in its operative position a movable conductive bridging member represented by a roller, ball or the like capable of passing from the operative to the inoperative position or vice versa by the thrust action of opposing projections formed in the cut out portion of a sliding plate adapted to be displaced relatively to said bridges, said cut out portion being provided with pairs of respectively opposed notches adaptedy to cooperate with small guiding partitions located at the sides of and adapted-to guide the respective bridges, wherein the two conductive arms arranged in pincer like fashion of each switching unit are provided at their respective intermediate portions with oppositely curved seating portions, adapted to oooperatively receive and retain the related movable bridging member, one of the pincer arms of each unit having an end extension that continues from the associated curved portion and is so shaped as to facilitate the release and entrance of the bridging member, while the other resilient pincer arm of the same unit has a bent resilient eXtensionthe free end of which is arranged at such a distance from the nearest part of the curved seating portion of the same arm, that the movable bridge is capable of moving past said curved portion of the freev end without breaking its Contact with the conductive arm, an insulating shoe being mounted on the above mentioned free end of the resilient bent extension which when the contact bridge is in its operative position, remains normally interposed between the conducting portions of the related arm and the other conductive arm, thus blocking the access of the contact bridge to the conductive pincer, said shoe having in addition a contact zone facing an associated portion of the other member, to form with said portion a resilient pair for the impulsion of the contact bridge towards the inside of the pincer, during the operative stroke of said bridge, said sliding plate being slidingly mounted in parallel relationship with an intermediate base plate which in turn is xedly mounted at a distance from a main base plate, the pincer arms being firmly attached to a. vertical partition.

l0. In an electrical switch, a plurality of electrical switching units, each unit including two resilient conductive arms arranged in pincer like fashion and adapted to retain in its operative position a movable conductive bridging member represented by a roller, 'ball or the like capable of passing from the operative to the inoperative position or vice versa by the thrust action of opposing projections formed in the cut out portion of a sliding plate adapted to be displaced relatively to said bridges, said cut out portion being provided with pairs of respectively opposed notches adapted to cooperate with small guiding partitions located at the sides of and adapted to guide the respective bridges, wherein the two conductive arms arranged in pincer like fashion of each switching unit are provided at their respective intermediate portions with oppositely curved seating portions, adapted to cooperatively receive and retain the related movable bridging member, one of the pincer arms of each unit having an end extension that continues from the associated curved portion and is so shaped as to facilitate the release and entrance of the bridging member, while the vother resilient pincer arm of the same unit has a bent resilient extension the free end of which is arranged at such a distance from the nearest part of the curved seating portion of the same arm, that the movable bridge is capable of moving past said curved portion of the free end without breaking its contact with the conductive arm, an insulating shoe being mounted on the above mentioned free end of the resilient bent extension which when the contact bridge is in its operative position, remains normally interposed between the conducting portions of the related arm and the other conductive arm, thus blocking the access of the contact bridge to the conductive pincer, said shoe having in addition a contact Zone facing an associated portion of the other member, to form with said portion a resilient pair for the impulsion of the contact bridge towards the inside of the pincer, during the operative stroke of said bridge, said sliding plate being slidingly mounted in parallel relationship with an intermediate base plate which in turn is iixedly mounted at a distance from a main base plate, the pincer arms being firmly attached to a vertical partition, and a cover being provided to protect the essential elements of the switch, tted over the main base plate and provided with an aperture in its front for the passage of a handle adapted to operate the sliding plate from the outside of said boX.

SARA MARIA IRIBARREN DE OLARIAGA.

LUIS BULGARINI.

PERCY FORSTER.

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