US2880290A - Push-pull wall switch - Google Patents

Description

March 3l, 1959 E. T. PLATZ 2,880,290

PUSH-PUSH WALL. SWITCH Filed Oct. 18, 1957 2 Sheets-Sheet l INVENTOR. Zit/da 7? ,0L/47X vBY MDW/@WM `March 31, 1959 E, T, PLATZ PUSH-PUSH WALL SWITCH 2 Sheets-Sheet 2 Filed Oct. 18, 1957 @Nmv v,

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PUSH-PULL WALL SWITCH Elwood T. Platz, Detroit, Mich., assignor, by mesne assignments, to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania This invention relates to wall mounted switches commonly used in the home to control room lighting circuits and more particularly to a switch which is operated to both its on and off position by depressing a single operating button.

Prior art switches of this type present certain production difficulties since they employ springs which must be loaded for installation and in this condition are diicult to install using automatic assembly methods. In use, the prior art switches have exhibited a short life since many of their members are in frictonal engagement and wear rapidly unless they are fabricated of expensive materials.

The switch of the instant invention provides a pushpush operation and utilizes a construction which lends itself to automation assembly methods by eliminating springs and by inserting all of the elements into the housing with a straight downward movement. This construction eliminates all friction engaging members and is her- -metically sealed to exclude dirt thereby assuring long switch life. In operation, the switch is silent, is light to the touch, displays no mechanical feel, and requires a short operating stroke.

In essence, the wall switch of the instant invention comprises a pivoted member which acts to bridge the gap between two stationary contacts when in a rst position and to open the gap when in a second position. The pivoted member is operated between its first and second positions by utilizing an external operating button to transfer weight carried by the pivoted member from one side of the pivoted members pivot point to the other side. This transfer of weight will cause a pivoting of the pivoted member from one of its positions to the other.

In order to obtain silent operation, this switch utilizes mercury as the weight which is transferred through a connecting passage between two pockets, in the pivoted member, positioned on opposite sides of the pivot point. The operating button is mounted to a rubber-like gasket and, when depressed, forces a protrusion to engage a rubber-like covering over one of the pockets thereby forcing mercury out of this pocket into the pocket on the other side of the pivot point thereby causing the pivoted member to rotate from its rst to its second position.

The next time the operating button is depressed the other mercury pocket is so positioned that a protrusion will engage the rubber-like covering of this pocket and force the mercury back to the first pocket thereby rotat- United States Patent C) ing the pivoted member back to its lirst position. In this manner, successive operations of the operating button will cause the pivoted member to oscillate between its rst and second positions.

Switch operation is also rendered noiseless in that the stationary contacts comprise isolated mercury pools formed in the switch housing. vThe pivoted member carries a movable contact which includes two protrusons extending radially outward and axially displaced so that in the rst position of the pivoted member the contact protrusions will be entered into the mercury pools thereby bridging the gap therebetween to complete the electric circuit controlled by the switch.

Accordingly, a primary object of this invention is to provide a reliable wall switch of simplified construction utilizing a single operating button to achieve push-push operation.

Another object is to provide a push-push type wall switch having silent operation.

Still another object is to provide a push-push type wall switch that requires a short operating stroke, is light to the touch, and displays no mechanical feel.

A further object is to provide a push-push type wall switch that is hermetically sealed and eliminates the frictionally engaged moving parts and operating springs thereby assuring long switch life.

A still further object is to provide a push-push type wall switch that includes a movable contact that is operated between its engaged and disengaged positions by means of a transfer of mercury from one pocket to another. v

Yet another object is to provide a push-push type wall switch wherein a movable contact is utilized to bridge the gap between two stationary pools of mercury which comprise stationary contacts.

These as well as other objects of the instant invention will become apparent after reading the following description of the accompanying drawings in which:

Figure l is a front elevation of the switch with the surface plate broken away.

Figure 2 is a section taken along line 2 2 of Figure 1 looking inthe direction of arrows 2 2.

Figure 3 is a front elevation of the pivoted member or rotor of the switch illustrated in Figure l.

Figure 4 is a section taken through line 4 4 of Figure 3 looking in the direction of arrows 4 4.

Figure 5 is an end view of the rotor of Figure 3 looking in the direction of arrows 5 5,

Figures 6 and 7 are a back elevation of the switch of Figure l with the rotor in each of its two extreme positions.

Figure 8 is a section taken through line 8 8 of Figure 6 looking in the direction of arrows 8 8.

Figure 9 illustrates an alternate method of mounting the projections which apply the force whereby the liquid carried by the rotor is transferred from one pocket to the other.

Figure l0 is a front elevation of a rotor used in a second embodiment of this invention.

Figure 1l is a section taken through line 11 11 of Figure 10 looking in the direction of arrows 11-11.

Referring more particularly to Figures 1 9, switch 12 is adapted to be secured by means of screws 13 to box 14 situated behind wall 15. Cover plate 17 fastened to switch 12 by fasteners 18 rests against the outside of wall 15 and completely covers the wall opening provided for box 14. Cable leads (not shown) entered into box 14 from behind wall 15 are readily attachable to switch terminals 24-26 by means of terminal screws 99.

Switch 12 comprises housing 61 of insulating material, has an internal cavity for receiving the rotor 62 which has a bearing shaft 63 with a reduced portion 64 at its right hand end for journaling in the housing 61 and fa reduced portion 65 on its other end for journaling in the bracket 66 which has legs 67 for positioning in the housing 61. Fasteners 16 secure legs 67 to bracket 66 whose ends are nested in approximately shaped recesses in housing 61. Rotor 62 is wafer-like in shape having in its periphery annular notch 68 whose extremity 70 engages the lug 71 formed in the housingl to limit the counter clockwise movement of the rotor 62.- The other extremity 72 of the annular notch 68 limits the clockwise movement of the rotor 62. These extremities ment of the rotor 62. Lug 71 may comprise a shock absorbing material such as rubber in order to assure silent operation.

Rotor 62 also includes :spherical pockets73 and 74 -whichiarepositioned xliametricallyzabout the bearing 63. .Annular channel 175 Yforms alconnection' between Apockets 73, 74 vwhich .are covered bya rubber-like sheet 76 bonded to the rotor 62 to hermetically seal mercury or Aotherfsuitableiiiuid Vcontained in the pockets 73, 74 for "a purpose to be explainedilater.

'.Housing'61. includes notches 77, 78 and 79 which form pools lfor mercury `or other suitable conducting uid. With referencev tov Figures l and 8,'well 79 extends from the curvedend 20'to.21, mercury'well 77 extends from `the Vcurvedrend2() to the curved end 22, and mercury Vfwfell 78ex'tendsfromithe"curved end 21 to the curved end 23. Terminals 24,125 and 26 are secured to the housing by the screws87, 88, 89 respectively which are ofdilerentlengthsrso that each-extends into one of the mercury pools v77`79`to forman electrical connection between the mercury andthe terminals. The center contact screw 88 projects into mercury well 79 to form an .electrical connection to terminal .25. `With reference to :Figure l, the right'hand contact screw 87 Vbypasses the .pools 78 land 79 and projectsinto mercuryfwell 77 to form an electrical connection to terminal 26. The left h'and contact screw y89 bypasses well 79 and projects into well 7S to forman electrical connection to terminal V2d. It will thus be apparent that the purpose of terminating .the wells-77,78 and 79v atv strategic points was to permit the contact screw 87--89 to bypass' certain mercury .pools 77-'79l-to'make`proper contact with'the terminals 24-26.

A rubber-like gasket 28 is clamped between the top 'surface of the housing61 and the'inside of mounting 'strap 45 by the screws y30 for the purpose of hermetically sealing the interior of the 'housing 6l. Gasket 28 includes 1an integrally formed push butto-n 29 on one side thereof Vwhich extends outward through opening 27 in the mounting strap 45. Gasket 28 has'on the other side, or inside, two f other integrally formed projectio-ns 31 and 32. 4Projection 31 is opposite the pocket 73 in the rotor 62. The right hand projection 32 is opposite the circular clearance notch y34. in the rotor 62.

Contact blades 35 and 36 are spaced apart by the :conducting bushing 37 and secured to the rotor 62 by vkmeansof the rivet 38. Withreference to Figure 2,' it Vwill be apparent that the blade 36 Vwill make contact with the mercury in well 78 and that the blade 35 will .make contact withfthe mercury in the well 77 when rotor 62 is in its counterclockwise position of Figure 6. An electrical connection will thus be established between terminals 25 and 26. Another similar pair of blades 43 `-and -44 are attached tothe rotor at 9) degrees from blades 35 and 36.

The latter set of blades is offset from the other pair `so that blade 43 is vin line with the well 78 and blade 44 is in line with the well 79. it will thus -bea'pparent that if the rotor 62 is caused to be rotated 90 degrees ina clockwise directionto the position of Figure 7, an electrical connectionwill'be formed between the termi- .nals 24 and 25. This plurality of pairs of contacts attached to the rotor762 is the essence of a three point switch. lt willLbe'fapparent that either pair of contact -blades could be .eliminated'with' its corresponding mercury well to constitute the common two point switch.

*With reference to ir'igure l, pocket 73 contains mercuryfapproximately/tothe level of the line-39 and the pocket 74 Ahas a residue of mercury approximately to .the leveLof vthe line 40. It will be apparent that vwhen .push button 2-9nis depressed, projection -31will press @against rotoVcoVer'761opposite the pocket `73 causing -vof111hen'otor. When'rpush button 29 ais lreleased, 4'the mercury, which now has risen in the pocket 74 to the level of approximately thel-line 41, will cause clockwise rotation of the rotor 62 because of the greater quantity of mercury in the pocket 74. Pocket 74 will now come to rest opposite projection .32. .It will now be apparent that when button 29 is again depressed, mercury will ow from the .well'f74 to the well 73 to cause counter clockwise rotation 'of the rotor 62. Thus, the mercury in .rotor pockets 173, y74 acts as a weight substantially all of which is :transferable back and forth through passage 65 upon-successive operations of button 29 in thesame-'drection'as projections 31, 32 engagel pockets 73, 74 respectively.

Rubber-like 'gasket 76 has formed embossrnents opposite pockets 73 and 74. The purpose of these embossments 19 is to eliminate any tendency of the rubber-like bulbs to `return when "theyfare depressed-by projections 31 'or 32, .thereby preventing the mercury from being drawn back. If-gasket A76 did vnot have these embossments 19,' the `rubber vvouldmerely stretch when depressed by projections 31 and 32 and would return when buttonl29 wasl released to ldraw the mercury back again. This construction of 4'etnbossments 19 in the lsheet76is in lieu v"of a"che`ck^ valve which ywould otherwise be required in 'thei'connecting channel'75.

In 'order Ato preventstalling of vrotor *62 atthe;;md

Yposition'and.thereby-render the device inoperative because I'neither of projection 31 or 32 Iwould be opposite pockets 73 or 74 but would be against a solid portion of fthe rotor 62, Weight i42 lis provided. Althoughfthis-'device 12 ishermeticallyt sealed against 'moisture and dustya r:slight amount offfriction in the journals 64 kand 65-may vbe suficient torcause 'the :rotor 62 to stall, --not when yas rotation .progresses because weight 42 is ,above the horizontal center line of the rotor. It should be. apparent that weight 42'maybe divided in half with each half being disposed on voppositelsides.ofthevertical centerline-:.98 of rotor162.

ReferringtoFigurelZ, it `will be noted thatthe tips of projectionsl, 32 :areotset above .the centerline `ofzthe pocket y73. With thisxrelative :positioning .projection 31 `willhave'arslightftendency to raise thepocket73 causing a slight amountofzclockwise: rotation to break .away` any static yfriction that may have accumulated'in the bearings 64 and 65 of therotor 62.

Figure 9.illustrates lugs.31a.and 32a attached toiiex'- ible metal.. member 46 which is in turn secured tothe bracket v66. This construction is 1 an .alternate embodianent' tol projections .31 and 32 integrally formed vwithzthe gasket 2S.

Interior 4metal parts such as the bearings63, the bracket 66, and ythe contacts should beof a ferrous material 'to vprevent amalgamation with the mercury. This bis likely to.. occur tothebearing 63v andthe bracket 66.du1ing shipmentor other. pre-tinstallationhandling. of` switch 12. During rthis period,'.the.mercu1'y.from the pools 77-79 mayfow throughout the interior of switch 12'but :will gravitate into these pools when the switch 12 is properly installedzwhich is with' the 'Top asindicatedin Figure l.

`Rotor 62 preferably comprises an insulating'plasti'c material. But',':rotor '62A could2 beofrmetal with integrally Aformeditcontacts. "The requirement, however, is: forza very light materialso that the .unbalance caused by .the :niet- "cury displacement*will be percentagewise as .large vas possible.

Figures 10 and 11 illustrate another embodiment of this invention having a rotor 46 of relatively thin material and having substantially the same contour, the same contacts, and bearing as the previously mentioned rotor 62. Rotor 46 has secured to its outer surface a substantially U-shaped tube 47 which forms an internal raceway for a plurality of balls 53 having a high density. Balls 53 are confined in the tube by the narrow neck 48 near each end of the tube. The operating rods 49 and 50 are guided by the housing in a suitable manner (not shown) and are attached to the push button 51. With reference to Figure 11, it will be apparent that when the button 51 is depressed that the rod 49 will enter pocket or leg 52 of the tube 47 causing the balls 53 to move into the upper pocket or leg 54 of the tube 47. The resultant transfer of the balls will cause an unbalanced condition causing rotor 46 to rotate in a clockwise direction when push button 51 under the influence of the spring 55, moves out again. This action is similar to the previously described embodiment.

It will also be apparent that rod 50 will be inactive in this cycle of operation as it will merely travel in clearance notch 34 in the rotor 46. With reference to Figure 1l, the balls in the leg 54 of the tube 47 are the residue similar to the mercury at the level 40 in Figure 1. It will also be apparent that the length of the tube leg 53 is greater than the combined lengths of the portions 56 and 57. These proportions of the tube 47 are necessary so that the fiowback of balls will always be less than the amount pushed into the upper leg of the tube 47. It will also be noted that rod 49 is slightly above tube 52 to cause a slight rotation in the clockwise direction to break away static friction and that the tube legs 53, 54 are flared at their extreme ends to aid in guiding rods 49, 50.

Wall switches of this type are frequently installed in homes and buildings during the construction period when considerable plaster or other foreign materials are prevalent. For this reason, the button opening 27 in strap 45 has been extended down and broadened to conform to the lower portion of the cavity in the housing 61. This prevents the previously mentioned foreign matter from collecting or being pinched between the cover 28 and the mounting strap 45.

Thus, I have provided a reliable push-push type wall switch which achieves silent operation, requires a short operating stroke, is light to the touch, and does not display a mechanical feel.

This switch 12 is ideally suited to assembly by automation because of the absence of any springs which `are difiicult to assemble by this method and because all of the parts can be inserted into the housing with a straight downward movement. Furthermore, the mercury can be easily measured and deposited automatically. The cover 76 and the gasket 28 also lend themselves well to continuous feed operations.

In the foregoing, I have described my invention only in connection with preferred embodiments thereof. Many variations and modifications of the principles of my invention within the scope of the description herein are obvious. Accordingly, I prefer to be bound not by the specific disclosure herein but only by the appending claims.

I claim:

' 1. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said first and second positions by means of said weight being transferred between said first and second pockets.

2. An electric switch comprised of a housing, a pair of stationary contact, a rotor; said pair of stationary cons tacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said first and second positions by means of said weight being transferred between said first and second pockets; means operable externally of said housing and operatively positioned to engage said first and second pockets when said rotor is in said second and first positions respectively; engagement of one of said pockets by said means being effective to force at least a portion of said weight to the other of said pockets.

3. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said first and second positions by means of said weight being transferred between said rst and second pockets; said weight being comprised of a substance which is liquid at room temperatures.

4. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said first and second positions by means of said weight being transferred between said first and second pockets; said weight being comprised of mercury.

5. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said first and second positions by means of said weight being transferred between said first and second pockets; said pair of stationary contacts each being comprised of a substance which is liquid at room temperatures and electrically conducting; said liquid being confined in pools disposed internally of said housing. I

6. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pvot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second Aposition wherein 'said vstationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said first and second positions by means of said weight being transferred between said first and second pockets; said pair of stationary contacts each being comprised of mercury confined in pools disposed internally of said housing.

7. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second positoin wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a Weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said first and second positions by means of said weight being transferred between said first and second pockets; said weight being comprised of a plurality of spherical members.

8. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a rsecond pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said rst and second positions by means of said weight being transferred between said first and second pockets; said anti-stalling means, carried by said rotor, comprising a weight means disposed in a plane parallel to the plane of said rotor symmetrically about the vertical centerline of said ro-tor and operatively positioned above a line passing through said pivot point and perpendicular to said vertical centerline.

9. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said first and second positions by means of said weight being transferred between said rst and second pockets; means operable externally of said housing and operatively positioned to engage said first and second pockets when said rotor is in said second and first positions respectively; engagement of one of said pockets by said means being effective to force at least a portion of said weight to the other of said pockets; said means operatively positioned to engage'said pockets above the horizontal centerline thereof.

l0. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and .movable between a first position wherein said 'stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said first and second positions by means of said weight being transferred between said first and second pockets; means operable externally of said housing and operatively positioned to engage said first and second pockets when said rotor is in said second and first positions respectively; engagement of one of said pockets by said means being effective to force at least a portion of said Weight to the other of said pockets; a rubber-like sheet means bonded to said rotor and covering each of said pockets; said rubber-like sheet means having embossments at points coinciding with said pockets.

l1. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said first and second positions by means of said weight being transferred between said first and second pockets; means operable externally of said housing and operatively positioned to engage said first and second pockets when said rotor is in said second and first positions respectively; engagement of one of said pockets by said means being effective to force at least a portion of said weight to the other of said pockets; a rubber-like sheet means bonded to said rotor and covering each of said pockets; said rubberlike sheet means having embossments at points coinciding with said pockets; said means operatively positioned to engage said rubber-like sheet means above the horizontal centerlines of said pockets.

l2. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing, said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being movable between said first and second positions by means of said weight being transferred between said first and second pockets; said weight being comprised of mercury; said pair of stationary contacts each being comprised of mercury confined in pools disposed internally of said housing.

13. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; sai-d rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being moved to said first position when the amount of said Weight in said first pocket is substantially greater than the amount of said weight remaining in said second pocket; said rotor being moved to said second position when the amount of said weight in said second pocket is substantially greater than the amount of said weight remaining in said first pocket.

14. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a rst position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being moved to said first position when the amount of said weight in said first pocket is substantially greater than the amount of said weight remaining in said second pocket; said rotor being moved to said second position when the amount of said weight in said second pocket is substantially greater than the amount of said weight remaining in said first pocket; a first and a second projection operatively positioned within said housing; biasing means urging projections to a first position; said projections being movable in unison against the force of said biasing means to a second position; said rst projection engaging said first pocket and said second projection being received by a notch in said rotor when said rotor is in its said first position and said projections are in their said second position; said second projection engaging said second pocket and said first projection being received by said notch when said rotor is in its said second position and said projections are in their said second position.

15. An electric switch comprised of a housing, a pair of stationary contacts, a rotor; said pair of stationary contacts being disposed within said housing; said rotor being pivotally mounted within said housing to a pivot point and movable between a first position wherein said stationary contacts are bridged by said rotor and a second position wherein said stationary contacts are insulated from one another; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being moved to said first position when the amount of said weight in said first pocket is substantially greater than the amount of said weight remaining in said second pocket; said rotor being moved to said second position when the amount of said weight in said second pocket is substantially greater than the amount of said weight remaining in said rst pocket; a first and a second projection operatively positioned within said housing; biasing means urging projections to a first position; said projections being movable in unison against the force of said biasing means to a second position; said first projection engaging said first pocket and said second projection being received by a notch in said rotor when said rotor is in its said first position and said projections are in their said second position; said second projection engaging said second pocket and said first projection being received by said notch when said rotor is in its said second position and said projections are in their said second position; a resilient gasket covering an opening in a wall of said housing; an operating button secured to said gasket on a first side thereof and projecting through said opening externally of said housing; said operating button when depressed being operatively positioned to move said projections toward their said second position.

16. An electric switch comprised of a housing, a rotor, a first, a second and a third stationary contact; said rotor being pivotally mounted within said housing to a pivot point and movable between a first and a second position; said rotor including a first and a second pocket disposed on horizontally opposite sides of said pivot point; a weight transferable between said first and second pockets through a passage therebetween; said rotor being moved to said first position when the amount of said weight in said first pocket is substantially greater than the amount of said weight remaining in said second pocket; said rotor being moved to said second position when the amount of said weight in said second pocket is substantially greater than the amount of said weight remaining in said first pocket; each of said first, second, and third stationary contacts comprising mercury confined in separate pools disposed within said housing and insulated from each other; said rotor having a first, a second, a third and a fourth blade radially projecting therefrom; said first and second blades being electrically connected; said first and second blades being disposed within the pools confining said first and second stationary contacts respectively when said rotor is in its said first position; said third and fourth blades being disposed within the pools confining said second and third stationary contacts respectively when said rotor is in its said second position.

References Cited in the file of this patent UNITED STATES PATENTS

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