US3497137A - Selector panel - Google Patents

Description

J. KOSMIS SELECTOR PANEL v 3 Sheets-Sheet 1 Filed Aug. 7, 1967 Feb. 24,1910 J. K SMIS 3,497,131

SELECTOR PANEL Filed Aug. '7, 1967 S Sheets-Sheet 2 3 g- 6i; m 3

4 Feb. 245.1970 j I J. KOSMIS H ,497,1

SELEcTOR PANEL Filed Aug. 7, 1967. 3 Sheets-Sheet, s

United States Patent US. Cl. 235-55 8 Claims ABSTRACT OF THE DISCLOSURE A selector panel for use in a voting machine comprises a selector mechanism having at least one series of depressable selector buttons, each of which is provided with a stern. A guideway extends along the ends of the stems of a series of the buttons, and has openings through which the end of the stem of each button projects into the guideway when that button is depressed. The width of each such opening, measured laterally of the guideway, is less than the lateral width of the guideway. A plurality of spacing members which are longitudinally displaceable in the guideway to permit the end of a stem to enter the guideway, are adapted to fill the guideway, after a predetermined number of keys in the series have been depressed, to prevent any further keys in the series from being depressed. These spacing members include a plurality of elongated cylindrical rollers which extend laterally in the guideway across the openings that admit the ends of the stems. Two of such rollers are normally positioned opposite the end of each stem to permit the end of the stem to penetrate between the two rollers when the corresponding button is depressed.

BACKGROUND OF THE INVENTION The presnt invention relates to a selector panel for use in a registering device or similar device, comprising a selector mechanism, having at least one series of selector buttons, the stem of each of these buttons having a cam or wedge portion cooperating with a pair of elements movable apart by depression of the button, said pairs of elements being received in a common guideway means and being movable longitudinally therein to such an extent that a limited member of selector buttons can be actuated at a time.

Selector panels of this type are used e.g. in voting machines. In a Well-known construction of such a selector panel the elements of the guideway cooperating with the stems of the selector buttons are in the form of balls, which are longitudinally freely movable in the guideway between fixed abutments at the two ends of the guideway. The diameter of the balls is large in comparison to the thickness of the stems of the buttons, which is necessary to prevent the balls from entering either partially or completely into the openings through which the button stems pass into the guideway, which would lead to disalignment of the balls. Due to the relatively large diameter of the balls the selector buttons have to be depressed a relatively large amount, while the balls are relatively heavy. The relatively large weight of the balls will be disadvantageous, particularly with a selector panel comprising a large number of selector buttons, in which case the depression of at least some of the buttons may be difficult in view of the relatively large total weight of the balls to be displaced.

SUMMARY OF THE INVENTION One object of the invention is to provide an improved selector panel avoiding the above drawbacks of the wellknown selector panel and making it possible to extend the number of selector buttons in each series at will, while maintaining accurate and easy operation and actuation of all of the selector buttons.

To this end according to the present invention the elements cooperating with the selector button stems are constituted by relatively thin, preferably cylindrical smooth elements, which are longitudinally pressed against each other in said guideway by 'means of a spring-loaded plug member at at least one end of the guideway means and extending transversely slightly beyond the lateral confining edges of the openings which receive the button stems. The relatively thin elements as proposed by the present invention may have a total weight which is only a fraction of that of the ball elements in the well-known construction. In the case of thin rollers, which is the preferred form of the elements, undesired turning movements of the rollers in their planes are prevented because the rollers are resiliently pressed again each other.

A further object of the invention is to provide a selector panel of the type referred to in which the guideway may be simply lengthened or shortened in accordance with the number of selector buttons, which are needed. To this end the guideway means is composed of separate elements secured to a common base and joining each other along surfaces which are oblique with respect to the longitudinal axis of the guideway. Thus the guideway may be given a larger or smaller length by simply securing a larger or smaller number of guideway elements to the common base.

In case rollers are used as runner elements in the guideway the axes of these rollers cross the joints between the individual guideway elements so that there is no danger of the rollers moving out of their path by entering partially into the joints between the guideway elements.

According to a further feature of the present invention at some points, e.g. at one end, the guideway is penetrated by a blocking member connected to a main selector button and having an escape recess(es), said blocking member normally, i.e. when the main selector button is released, blocking the rollers in the guideway but upon depression of the said main button presenting its escape recess(es) to the adjacent roller(s) which thus far may enter this (these) escape recess(es) so as to make it possible to depress a limited number of the other (ordinary) buttons.

Still further in accordance with the invention the main selector button may cooperate with a pair of rollers in a guideway element extending transversely to the other guideway, the rollers in said guideway element being movable apart transversely to the direction of the movement of the other rollers in the other guideway, and being captured in said guideway element between plug members extending just beyond the lateral ends of said guideway element.

The latter construction makes it possible to put, in a manner known per se, a plurality of series of selector buttons as columns in side by side relationship, whereby the guideway elements associated with the main selector buttons of the columns are coupled by means of the plug members of said guideway elements acting as coupling members.

The guideway elements associated with the various main selector buttons may form a main guideway, in which the pairs of rollers and coupling members are ca tured between a spring loaded plug member at one end of the main guideway and another spring loaded plug member at the other end of the main guideway, the latter plug member being adapted to be locked in its innermost position.

In this way a selector panel of simple and reliable construction is obtained, comprising a number of side by side columns, which can be operated by first selecting a certain column bydepressing the associated main selec-- selected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view of a selector panel according to the present invention, applied in a voting machine;

FIG. 2 is a rear perspective view of the inner structure of one selector column, some of the interior parts being broken away and the surrounding box or casing being completely removed for purposes of clarity and simplicity, a main selector and an ordinary selector button taking their depressed position and portions of an adjacent selector column being represented in exploded condition;

FIG. 3 is a vertical sectional view of the lower end part of the guideway in a selector column;

FIG. 4 is a side view of a selector button with an associated locking arm;

FIG. 5 is a horizontal sectional view of the left end part of the horizontal main guideway shown in FIG. 2;

FIG. 6 is a perspective view showing a part of the upper horizontal locking bar, cooperating with the upper end portion of a vertical locking bar;

FIG. 7 is a horizontal sectional view, showing a number of selector buttons belonging to separate columns; and

FIG. 8 is the electrical wiring diagram showing the solenoids and switches applied in the voting machine.

With reference to FIG. 1, 1 represents the front panel of a voting machine, said panel being principally constituted by a large number of selector buttons 2, which are arranged in side by side columns 3. 4 indicates the voting button and 5 designates a pilot light.

The selector buttons 2 belonging to each of the individual columns are mounted in a frame 6 (FIG. 2) which in turn is guided and locked in place in a manner known per se as a tray within the frame (not shown) of the voting machine.

Behind each column 3 of selector buttons there is a guideway 7 containing rollers 8 movable therein. In the embodiment shown the guideway 7 consists of a number of individual elements 7a joining each other along surfaces 9 which are oblique relative to the longitudinal axis of the guideway so that the joints between the successive guideway elements 7a are crossed by the axes of the rollers 8. The guideway elements 7a the number of which, in the embodiment shown, equals the number of the selector buttons 2, are secured (by fastening means not shown in the drawing) to a vertical wall portion 10 of the column frame 6.

The guideway 7 is closed at its lower end by a plug member 11 having a shape which is complementary to the cross-sectional shape of the guideway. The plug member 11 is urged into the guideway by a spring 12 but can be displaced outwardly (e.g. a distance of about 1.5

locking arm 15, an abutment face 15a (FIG. 4) of which serving to limit the outward (releasing) movement of the selector button and for that purpose cooperating with an abutment pin 16 projecting from a bar 17, which is fixedly secured to the respective column frame 6 in any suitable manner. At its free end the locking arm 15 has a cam surface 15b disposed at an angle relatively to the direction of depression of the selector button 2 and cooperating with one of the projecting pins 18 of a locking bar 20 which is movably mounted in the direction indicated by the arrow I and urged into its upper position by a spring 19. The locking bar is guided adjacent its upper and lower ends in guiding brackets 22 secured to a sidewall portion 21 of the column frame 6.

The pins 18 of the locking bar 20 project through slots 23 in the sidewall portion 21. When a selector button 2 is depressed the sloping cam surface 15b of the locking arm 15 moves past the associated pin 18 of the locking bar 20 and thereby causes said pin to move downwards, so that the locking bar 20 is displaced downwardly against the action of the spring 19 until the pin 18 is allowed to move upwardly again, into engagement with the abutment surface 15a. Thus the depressed button is locked in its depressed position (see the button indicated at A in FIG. 2). When after this another selector button of the same column is depressed, the locking bar 20 will be moved downwardly by the sloping cam surface of the locking arm of that button. As a result of this the pin 18, which up to that time was held locked, is disengaged from the abutment surface 15a of that first button, so that this first button is allowed to return to its initial position by the action of its associated spring 13a. Thus each time a selector button is depressed a previously depressed selector button is released from its depressed position and allowed to return to its inoperative position. This means that a selection made as a result of the depression of a certain selector button of a column can be corrected by I depressing another selector button of the same column.

millimeters) against the action of this spring when a selector button is depressed as will be more fully explained hereafter (FIG. 3).

The guideway elements 7a each have a hub-like portion 13 with a central opening 13b having a non-circular cross-section in which the correspondingly shaped (i.e. square) stem 14 of an associated selector button 2 is guided. The width of each such opening, measured laterally of the guideway, is less than the lateral width of the guideway 7, and the cylindrical rollers 8 areelongated and extend laterally in the guideway 7 across such openings. The hub-like portions 13 of the guideway elements 7a are surrounded by coiled springs 13a, urging the respective selector buttons 2 outwardly.

With the exception of the uppermost selector button, which will be described separately, all of the other selector buttons of each of the columns are provided with a The guideway 7 is closed at its upper end by a plug member 24, which is urged downwardly by a spring (not shown) into the guideway and the upper end of which normally contacts a blocking bar 26, connected with the uppermost selector button of the column, which button has been indicated by H and is to be seen as the main selector button of the column.

Normally, when none of the ordinary selector buttons 2 is depressed, the rollers 8, which function as spacing members, and which are rounded off at their ends, are captured between the plug members 11 and 24 without any clearance between the successive rollers as may be seen from the drawings. The free ends 14a of the stems 14 of the selector buttons 2 are wedge-shaped.

In order to enable a certain selector button to be depressed the wedge-shaped end 14a of the stem of that button must be allowed to penetrate transversely through the guideway, to which end it is necessary that the rollers which are above and under that location in the guideway move upwardly and downwardly respectively. The downward movement is always possible, because the lower plug member 11 can be moved outwardly against spring action. The upper plug member 24 however, normally i.e. when the main button II is not depressed, abuts the blocking bar 26 and consequently is not allowed to move upwardly. Such a movement is permitted only after depression of the main selector button, whereby a recess 26a of the blocking bar 26 is moved into alignment with the plug member 24, into which recess the plug member 24 may escape under the action of a force applied to it via the rollers 3 by the upper sloping surface of the wedge-shaped end 14a of the stem of the depressed ordinary selector button.

In this connection it is to be understood that the first part of the depression stroke of a selector button is a lost motion, in the sense that the wedge-shaped stem end 14a of a button will engage the rollers in the guideway only after a certain initial depression. This lost motion is needed in order to cause a previously depressed selector button, if any, to return to its inoperative position and to disengage its stem from the guideway in the above manner. Only thereafter the guideway is free for penetration by the stem of the new selected button.

By carrying out one of the selector buttons of a column as a main selector button II the possibility is obtained to select first a certain list from a number of selection lists or parties which are each represented by a column, by depressing the main selector button of the respective column, after which from the selected list or party a certain candidate is selected by depressing the selector button associated with said candidate from the column which has already selected and deblocked by the previous depression of the main selector button of said column.

The guideway element 7b associated with the main selector button II is disposed transversely to the guideway 7 and constitutes, together with the guideway elements associated with the main selector buttons of the other columns, a horizontally disposed main guideway or connecting guideway VII. In each guideway element 711 of this main guideway there is at least one pair of rollers 27, cooperating with the wedge-shaped stem end of the associated main selector button II.

The guideway elements 7b have their end faces perpendicular to the longitudinal axis of the guideway VII. The space between each two guideway elements 7b is bridged by coupling members 28 which are slidably mounted in said guideway elements and project beyond the opposing end faces of the two guideway elements. In the embodiment shown in the drawings the main guideway constituted by the elements 7b is closed at its left end by the coupling member 28 projecting at that end beyond the utmost left guideway element 7b. The latter coupling member 28 (FIG. 5) is arranged in a manner similar to the plug member 11 at the lower end of the vertical guideway and thus may move a certain distance outwardly from the left end of the horizontal main guide way, against the action of a spring 25, to enable the depression of a main selector button II. The spring 25 is housed in a block 25a which may be part of the frame of the voting machine.

At its right end the main guideway is closed by the coupling member 28 projecting at that end beyond the extreme guideway element 712. The latter coupling element bears on a blocking lever 31 which is pivotally mounted on a pin 30 fixed to a part 29 of the frame of the machine, the free end of said lever being shaped as a gear segment 32, which cooperates with a blocking catch or pawl 34, which is movably guided in a direction indicated by the arrow P and which forms part of the armature of a solenoid 33. The blocking lever 31 is urged to the left by a spring 36. In the position shown in FIG. 2 the armature of the solenoid 35 takes its upper position in which the blocking catch 34 engages the gear segment 32 of the blocking lever 31. Thus the blocking lever 31 is blocked in its extreme left position.

In the horizontal main guideway the rollers 27 and the coupling members 28 are bearing one against the other and captured without clearance between the extreme left and right coupling members 28. In the position shown in FIG. 2 in which the blocking lever 31 is blocked in its extreme left position, the extreme right coupling member 28 is not permitted to move to the right, which means, that in that condition none of the main selector buttons II can be depressed. This also means that none of the ordinary selector buttons 2 can be depressed either.

When, however, the armature and the blocking catch 34 connected with it are moved into their lower position as by energizing the solenoid 33, the blocking lever 31 and thus the extreme right coupling member 28 can be moved to the right against the action of the spring 36. In that condition one of the main selector buttons II can be depressed, after which the column of buttons associated with that main button is released for further selection. When depressing the said main selector button the wedge-shaped stem end of that button penetrates between the respective pair of rollers 27, thereby moving these rollers apart, the left roller of the said pair moving to the left together with the extreme left coupling member 28 and the right roller of said pair movin to the right together with any further rollers and coupling members at the right side thereof, and swinging the blocking lever 31 to the right. The distance which can be covered by the blocking lever 31 when moving from its extreme left position to the right is such that only a limited number of main selector buttons II, in this example only one single button, can be depressed simultaneously before the spacing members 27 and 28 completely fill the main guideway.

By the depression of a certain main selector button II the voter in the first place has selected a certain party, while by the subsequent depression of one of the ordinary buttons 2 of the column associated with the depressed main selector button a certain candidate of said party has been selected. For counting the number of votes on each party, as well as for counting the number of votes on a certain candidate of that party each of the selector buttons 2, II cooperates with a counter 35, an actuating member 37 of which cooperates with the wedge-shaped stem end 14a of the associated selector button.

For claritys sake one counter has been represented only. The depression of a certain selector button, however, does not yet result in actuation of the counter. The depression of the button merely results in that the actuating member 37 of the counter in question is moved into a position of preparation of the counting operation. More specifically the actuating member 37, by the depression of the associated selector button, is subject to a rectilinear displacement against the action of the spring 38 in a guide block 39 pivoted about a pin 39a. The proper counting operation is effected by actuating a separate member, which is constituted by a counting bar 40 which is common to all buttons of a column and which is provided with projecting pins which may each cooperate with an actuating member of a counter in the said position of preparation to effect the counting operation. To this end the counting bar 40 is mounted for vertical sliding movement in bearings 40a secured to the wall portion 10 of the column frame. A spring 42 surrounding the upper end part of the counting bar 40 urges this bar into its lower position. By moving the counting bar 40 upwardly against the action of the spring 42 an additional movement is given by one of its projecting pins 41 to the prepared actuating member of the counter associated with the depressed selector button II and the depressed ordinary selector button 2, said additional movement in this example being an upward swinging movement about the pivot pin 39a, as a result of which the operative end 37a of the actuating member 37 moves the small gear 35a of the associated counter 35 through a unitary angle.

The other pins 41 remain disengaged from the actuating members of the other counters which have not been placed in a position of preparation. The upward movement of the counitng bar has to take place after the choice has been definitely made and is effected by the depression of the voting button 4. The depression of the voting button 4 causes an actuating rod 43 arranged under the column 3 to move to the left as seen in FIG. 2.

Under each of the columns 3 there is a cam 44 carried by the actuating rod 43, cooperating with a projectlng pin 45 on the end portion of the counting bar 40, projecting beyond the lower end of the column. When the actuatin rod 43 is moved to the left the projecting pin 45 may be urged upwardly by the cam 44 together with the counting bar 40, resulting in the counting operation explained above. This cooperation between cam 44 and projecting pin 45, however, only occurs with the selected column. For the counting bars 40 are not mounted for vertical movement only but also for movement between two angular positions. Normally, i.e. when the main selector button II of a given column is not depressed, the counting bar of the column takes an angular position in which the pins are out of the paths of the actuat ng members 39 of the counters 35 and in which the projectin pin 45 is out of the path of the associated cam 44. Only when the main selector button 11 of the column is depressed the counting bar is moved into its second, operative angular position in which the pin extends into the path of the actuating member 39, as far as the latter has been placed in its position of preparation and in which the lowermost projecting pin 45 extends in the path of the associated cam 44.

For this purpose the blocking member 26 carried by the main button II has a bifurcated crank pin 46 adjacent its free end, which crank cooperates with an additional projecting pin 47 of the counting bar 40 so as to move this counting bar through an angle (of about 90 in this embodiment) into its operative angular position. This construction has the advantage that for the final voting operation, whereby the vote is added to the number of votes, counted in previous selecting and voting cycles, only the counting bar of the selected columns needs to be actuated. Thus the friction to be overcome is minimized, promoting a light and reliable operation of the selection mechanism. The upward movement of the counting bar 40 just described is accompanied by a downward movement of the locking bar 20, as a result of which the depressed selector button 2 is released and may return to its initial position, ready for a following selection. To this end the movement of the counting bar '40 is transmitted to the locking bar 20 by means of a bell crank lever 48 pivotally mounted on a fixed pin 48a under the associated column 3. The bell crank lever 48 engages a projecting pin 49 of the extension 20a of the locking bar 20 extending beyond the lower end of the column and further engages a projecting pin 50 on the lower end portion of the counting bar 40, the latter pin being advantageously integrally formed with the projecting pin 45.

The distance covered by the locking bar 20 in its downward releasing movement just described, is larger than the distance covered by the locking bar under the action of the cam surface 15b of the locking arm 15 when depressing the button.

The downward unlocking movement of the locking bar 20 is attended by similar unlocking movement of an upper horizontal locking bar 51, which is similarly provided with projecting pins 52, cooperating with locking arms 53 carried by the main selector buttons II so as to lock an actuated main selector button II in its depressed position. For transmitting the unlocking movement of the vertical locking bar 20 to the horizontal locking bar 51 a wedge member 54 (FIG. 6) is provided adjacent the upper end of the vertical locking bar 20, said wedge member being adapted to engage an additional projecting pin 55 of the locking bar 51 when the said downward unlocking movement of the locking bar 20 is taking place, as a result of which the locking bar 51 is caused to move to the right, thereby releasing the depressed main selector button(s), so that the main selector button(s) can return to its (their) initial position, ready for a following selection.

In the embodiment shown in the drawings the depression of the voting button 4 effects energizing of the solenoid 57 as a result of which the armature 57a, as seen in FIG. 2 is pulled to the left, thereby taking the actuating rod 43 along against the action of a spring 56 through a coupling pin 58. When releasing the voting button 4 the spring 56 causes the actuating rod 43 to return to its initial position.

Simultaneously with the voting operationi.e. by

depressing the voting button 4-the machine should be put in a condition in which it is impossible to actuate the machine again after having released the voting button. For this purpose the actuating rod 43, while making its operative stroke, causes a switch S1 to open, as a result of which the energizing circuit of the solenoid 33, which had been initially closed by the official of the voting bureau as by depressing a push button switch D and had been kept closed through the switch S1 and the hold contact H of the solenoid 33, is opened again, thereby permitting the locking pawl 34 to move upwardly so as to lock the blocking lever 31 in its extreme left position as soon as the latter has returned to this position upon release of the main selector button II. The electrical wiring diagram of FIG. 8, which shows the switches mentioned above as well as the solenoid 33, also comprises the solenoid 57 associated with the actuating rod 43, which solenoid may be energized by closing the push button switch constituting the voting button 4.

Preferably each column comprises a switch K1, 2 n, which has to be closed first before the solenoid 57 associated with the actuating rod 43 can be actually energized. In this way the voting button is prevented from being effectively actuated until a selection between the (ordinary) buttons of the selected column has been made. It will be understood that these switches can be suitably mounted in the respective columns and that they might be actuated e.g. by the upper plug members 24 in the guideways 7.

The above voting machine can be easily adapted to any occurring number of parties or lists as well as to any occurring number of candidates of each party or list. The adaption to the number of parties or lists can be simply effected by putting more or less columns 3 including selector buttons 2 and counters as trays side by side in the frame of the voting machine, While the vertical guideways 7 can be easily lengthened or shortened at will by adding or removing guideway elements 7a.

If desired, the various locking bars, counting bars and actuation rods could consist of sections, in which case these parts of the machine could be lengthened or shortened at will also.

In the embodiment shown, certain buttons or series of buttons can be made completely ineffective, if desired, by means of an eccentric 59 mounted on each of the guideway elements 7a and 712, said eccentric being angularly movable in a plane perpendicular to the longitudinal axis of the vertical guideways between an inoperative position (marked by X in FIG. 7) and an operative position (marked by Y in FIG. 7). To move the eccentric 59 of a certain button 2 from the position X into the position Y the eccentric has to pass through the space alongside of the relative column which is possible only after removal of a filling strip 60 by which the said space is normally filled up. As has been diagrammatically shown in FIG. 1 the filling strips 60 are locked in place at their upper ends by means of a common locking rod 61 extending through openings (not shown) in the upper end portions of the strips and slidably mounted in the frame of the machine. The locking rod 61 may be pulled out to unlock the strips 60 for removal from the spaces between the columns 3 so as to render one or more selector buttons ineffective or additionally effective respectively by shifting the associated eccentrics.

I claim:

1. A selector panel for use in a voting machine, comprising a selector mechanism having at least one series of depressable selector buttons, each of which is provided with a stem; a guideway, extending along the ends of the stems of a series of the buttons, and having openings through which the end of the stem of each button projects into the guideway when that button is depressed, the width of each such opening, measured laterally of the guideway, being less than the lateral width of the guideway; and a plurality of spacing members which are longitudinally displaceable in the guideway to permit the end of a stem to enter the guideway but which fill the guideway, after a predetermined number of keys in the series have been depressed, to prevent any further keys in the series from being depressed, wherein the improvement comprises a plurality of such spacing members in the form of elongated cylindrical rollers which extend laterally in the guideway across said openings, two of such rollers being normally positioned opposite the end of each stem to permit the end of the stem to penetrate between the two rollers when the corresponding button is depressed.

2. A selector panel according to claim 1 wherein the guideway is composed of a plurality of separate elements having mating surfaces which are oblique relative to the guideway.

3. A selector panel, according to claim 1 comprising a blocking member which, in its normal position, blocks the spacing members against displacement in the guideway, and a depressa-ble main selector button which is connected to the blocking member to move the blocking member, when the main selector button is depressed, into a nonblocking position which permits displacement of the spacing members in the guideway.

4. A selector panel according to claim 3 wherein a plurality of series of selector buttons are provided with parallel guideways, and a series of main selector buttons are provided with a main guideway extending transversely to the other guideways.

5. A selector panel according to claim 4 wherein the spacing members include two plug members, arranged at the ends of each guideway, which are spring biased toward one another.

6. A selector panel according to claim 5 wherein the plug member at one end of the main guideway is adapted to be locked in its innermost position.

7. A selector panel according to claim 6 comprising a solenoid having an armature which is normally biased to lock the plug member at one end of the main guideway in its innermost position, an energizing circuit which can be closed to energize the solenoid and release the plug member, the solenoid being provided with self-holding contacts which are closed when the solenoid is energized, and a second solenoid which is supplied with current through pairs of contacts which are arranged in parallel, each pair being closed by depression of one of a series of selector buttons, the second solenoid being provided with normally closed contacts which are opened when the second solenoid is energized and which are in series with the self-holding contacts of the first solenoid.

8. A selector panel according to claim 1 wherein a locking bar is movable longitudinally of the guideway and is spring biased in one direction, and each key in the series is provided with a locking arm which, when the key is depressed, engages a projection on the locking bar to move the locking bar against its spring bias and then latches behind the projection to hold the key depressed.

References Cited UNITED STATES PATENTS 3,168,240 2/1965 ONeal 235-54 FOREIGN PATENTS 523,954 4/1931 Germany.

STEPHEN I. TOMSKY, Primary Examiner U.S. c1. X.R. 235-26

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