US2215584A - Electrical switch - Google Patents

Description

Sept. 24, 1940. R. HETHERINGTON ELECTRICAL SWITCH Filed Sept. 2l, 1937 2 Shre ts -Lveef Sept. 24, 1940. R. HETHERINGTON 2,215,584

ELECTRICAL SWITCH Filed Sept. 21, 1937 2 Sheets-Sheet 2 Patented Sept. 24, 1940 UNITED STATES PATENT OFFICE 13 Claims.

My invention relates to electric switches and supports ior they switches by which supports the switches are made adjustable within the path of some moving parts by which the switches are to be operated.

A purpose of the invention is to provide a thrust switch which may be either normally closed or normally open and which is opened or closed by the engagement of some machine member with an operating plunger carried by the switch.

A further purpose is to provide a multiple contact thrust switch whose contacts may be cleaned by rotation of a switch plunger.

A further purpose is to provide a thrust switch having a plurality of ilxed contacts and a plurality of movable contacts capable of movement directly toward and directly away from the fixed contacts and also capable of revolution o1' the' contacts by rotation of the plunger for the purpose of scouring the contacts against the iixed contacts. This may be either a one-way or a twoway switch.

A further purpose is to provide a spring pressed multiple contact switch with rotational lost motion for a movable contact-carrying member whereby the contacts can be cleaned by revolution of the contacts through an angle corresponding with the lost motion.

A further purpose is to provide a spring-pressed switch plunger, capable of rotation to scour movable contacts, with limiting mechanism by which the extent of scouring movement is limited, desirably using the spring to return the parts to approximate position and with or without lost mor tion in the connection with the spring.

A further purpose is to provide a two-way switch of plunger type having multiple contacts and in which the contacts are capable of being cleaned by an angular movement of the plunger,

A further purpose is to provide a thrust switch with a projecting plunger and with xed contacts and movable contacts, and a resistance automatically inserted when the switch is partly open along with mechanism by which complete closure through the resistance andcomplete opening of the switch are controlled.

A further purpose is to control the position of a resistance-inserting switch jointly by the action of a fabric-guiding motor and by a web-engaging i'eeler which responds to the position of the edge of the web.

A further purpose is to provide a band support for a contact switch acting much as a band brake,

a whereby the band may be loosened for adjustment of the position of the switch and then tightened to maintain the switch in adjusted position.

A further purpose is to provide a plunger switch with a cylindricalor square exterior surface and hold it by a band similar to a brake band, of

shorter band width than the length of the cylindrical section, so that by slacking the band the switch may be rotated or/and longitudinally moved to positions of adjustment and the band be again tightened to hold the switch in adjusted position.

Further purposes will appear in the speciilcation and in the claims.

My invention relates both to mechanisms and to methods which may be carried out by the use of some of the mechanisms. k

Figure 1 is a side elevation of a switch embodying my invention.

Figure 1a is a fragmentary elevation showing a variation of Figure 1.

Figure 2 is a central longitudinal section of the switch which is seen in Figure 1, the switch being closed. y

Figure 3 is a transverse section of Figure 1, taken upon line 3 3.

Figure 4 is a fragmentary longitudinal section corresponding generally to Figure 2 but with interior parts in `elevation and with the contacts separated.

Figure 5 is a section of Figure 2 taken upon line 5 5.

Figure 6 is an enlarged section of Figure 2 taken on line 5 6.

Figure 7 is an enlarged section corresponding in position to that on line 6 6 of Figure 2 but showing a modification.

Figures 8 and 9 are fragmentary longitudinal sections corresponding generally to ends of the switch in Figure 2 but showing modications.

Figure 10 is an enlarged longitudinal section showing a two-way switch.

Figure 11 is a section`^of Figure 10 taken on line Il l I.

Figures 12 and 14 are fragmentary longitudinal sections showing resistance-inserting switches.

Figure 13 is an enlarged sectional elevation of the plunger of Figure 12.

Figure l5 is a fragmentary sectional elevation of a portion of a cloth guider showing an application to which the switches of Figures 12, 13 and 15 are well suited.

Figure 16 is a fragmentary section showing a variation of the form of the contact carriers.

In the drawings similar numerals indicate like parts.

My switch is capable of general application. It is of plunger type and the plunger carries the movable switch contact elements. Preferably it is the intention that the actual current passing be split vup among a number of contact carrying elements engaged and disengaged by longitudinal movement of the plunger.

One form of support is illustrated which will be described iirst, recognizing the fact, however, that the switch unit may be mounted in many different ways and that the mounting shown is capable of use with switch units of many dlierent types.

The unit 2U is mounted upon any support 2| in position for longitudinal adjustment attained by means of a holding strap or band 22 and holding screws or bolts 23 and 24. The strap or band grips upon much the same principle as a band brake. It surrounds the switch unit.

One end 25 of the band is set to a proper position by screw 23 passing through the opening 26 and a screw or bolt 24 passing through the opening 21 in the other end tightens the band, putting the strap under tension and holding the tube in the longitudinal position into which it was set before the holding mechanism was tightened.

In the illustration the switch plunger is shown as operated by an arm 28 carried by a rod 29, but it is the intention that the plunger may be operable by any conventional or special mechanism by which axial plunger movement may be given.

The reason for selection of the operating members 28 and 29 is that the switch iinds one excellent use in operation by feelers adjacent the path of travel, in use with cloth guiders, of which one illustration is shown in my Patent No. 2,082,- 799 for cloth guider, issued June 8, 1937.

'I'he rod 29 in the illustration, Figure 1, could be, for example, such a feeler as that shown at 29 in Figures 1, la, 3 and 8 of above patent, though operating the switch through a bar carried by the extension of feeler arm below the n pivot point of the feeler.

If used in a cloth guider the support 2| could be any part of the frame of the guider; but equally can represent any other fixed member of mechanism in which a switch is required.

In Figure 4 the movement of the arm 28 is shown as a swinging movement about an axis such as the axis of rod 29 but obviously the character of the motion given may be greatly varied, taking its character from the type of movement characteristic of the control member of the mechanism with which the switch is to be used.

The unit illustrated at 20, for convenience and because it facilitates cheap manufacture is shown as a cylindrical unit; but here again the exterior and interior contours of the casing or shell are not controlling. It might, for example, be of square section.

With the cylindrical form shown, the center or body of the shell is .made up of a tube 30 whichis capped at 3| and 32. Both caps are open at the ends, at 33 and 34 respectively for passage of a rotatable or angularly oscillatory plunger, it being desirable to have the plunger pass through the caps and be guided by them at both ends of the unit. This gives access for operation and for rotation of the plunger to clean the contacts. This oscillation capacity for contact cleaning will be seen to be true of all of the forms. The caps are held in place by screws 35 and 39.

Each of the caps is apertured as seen in Figure 2 for the passage at 31 and 38 of the conductors 39 and 40, by which the electric circuit to be closed and to be broken is introduced within the unit.

The plunger 4|, for convenience of manufacture and insulation, is made in two parts. The end 42 and preferably most of the body of the plunger is desirably of insulating material as is also a sleeve 43 comprising the opposite end of the plunger. These two parts are separated in order that, conveniently, an electrically conducting contact carrier 44 may be gripped between them. The parts are held together by screw 45. The carrier 44 conveniently is made in the form of a disc or annulus, preferably flat. That it need not be nat is seen in the disc or annulus 44 in Figure 16.

Because it is the intention to split up the current passing through the switch among many contacts this electrically conducting carrier 44 is studded with electrically conducting pins 46 `which are arranged annularly about the contact face of the carrier. The carrier is electrically connected with conductor 39.

The carrier 44 through its conducting pins 46 makes contact with a second, and in this case a iixed electrically conducting carrier 41, (seen in Figure 16 as 47') through electrically conducting pins 48 corresponding generally with the pins 46. They are annularly arranged about the disc 41 and preferably have the same number and the same radial and circumferential spacing as the pins 46.

The switch shown in Figures 1, 2 and 3 is normally closed. This normal set of the switch is effected and maintained by a spring 49 which surrounds the plunger and presses the movable carrier, and hence the plunger, to the right in Figure 2 through engaging the disc 44 at one end and the interior of the cap 3| at 50 at the other end.

When the pins 46 and the movable disc are moved to the left oi Figure 2 the switch will be opened and conductor 39 slacked. This opening movement can be eiected by any means pressing against the right hand end of the plunger,

' as seen in that figure, to compress the spring 49;

and the extent of compression may vary greatly without interfering with proper operation of the switch.

It will be evident that for any predetermined movement of the operating means-such as movement of the arm ZB-the extent of plunger movement is adjustable by releasing the screw or bolt 24 until the unit can be shifted longitudinally within the strap held by it and then tightening the screw or bolt to hold the unit in its adjusted position. At the same time any desired circumferential adjustment of the unit may be effected.

One of many possible alternative means of adjusting the operating means (position and extent of throw) and plunger, relatively, is seen in Figure la where the arm 28', is made angularly adjustable to great nicety by splitting the arm at 282 adjacent the shaft 29 and using the split ends 283 as a clamp set in adjusted position by screw 284.

One of the considerable advantages of the structure seen in Figures 2 and 4 is that additiona1 slack may be given conductor 39 and, within the limits of rotation of the disc 44, permitted by the amount of slack, the plunger can be turned from either end, irst in one direction and then in another, while the pins of one disc are in contact with the pins of the other, the disc thus being ooscillated to rub each set of pins against the other, keeping the contact surfaces bright and maintaining good contact. The range of oscillation will be approximately twice the are of turning permitted in one direction by the slack of conductor 35'.

Various ways are available for limiting the extent of rotation of the plunger and movable disc carried by it. By the simple expedient of anchoring the ends of the spring against turning, the rotation in each direction can be limited to such winding orv unwinding of the coil of the spring as will conveniently take place during the turning of the plunger. This construction appears in Figures 2 and 6.

In Figure 2 the left end of the spring is shown as anchored at 5i Within one of the caps or ends of the casing, and in Figure 6 the opposite end of the spring is shown as anchored at 52 in the movable carrier 44. In Figure 6, however, the end of the spring does not fit within an opening merely as would be the case if it be desired to have the spring bring the parts back to the same point at all times, but instead the spring end ts into a slot 53. It may rest at any point in this slot but cannot go beyond its limits. This permits a larger angular extent of oscillation and provides an angular range, equivalent to the angle represented by the slot, Within any part of which angular range the carrier may come to rest after the oscillation has been eiected.

In Figure 7 the carrier 442 is circumferentially recessed at 54 throughout an angle corresponding to the intended angle of oscillation and oscillation is limited to this angular extent by a rib 55 whichis shown asprojecting within the interior of the casing.

In Figures 8 and 9 normally open multiple contact plunger switches are shown in fragmentary form. In each case lost motion is provided between the operating mechanism, by which the plunger is moved, and the contact carrier. It would be diflicult to adjust the operating mechanism so exactly that it would just close the switch and yet would always reliably close it. For this reason provision is made for overtravel of the operating mechanism, provided for in the lost motion.

In Figure 8, the parts of the casing are substantially the same as those seen in Figure 2 except that one of the conductors 39 passes into the casing through a lateral slot 56. 'Ihis provision better accommodates the movement of the electrically conducting carrier.

Upon plunger 4I is mounted an electrically conducting carrier 51 provided with contacts 46 all connected with the conductor 39'. For convenience the annulus carrier is supported by a cup-shaped holder 58 which is fastened to the plunger in any suitable way, as by pin 59. The spring 49 forces the movable disc away from the lxed disc 41 so that the switch is normally open. Between the spring 49 and the cup 58 is located an insulating cup Washer 60. The switch is intended to be closed by movement of the plunger from right to left in this Figure 8.

At some intermediate point in the plunger a lost motion mechanism is located. It is shown as comprising a spring 6I and a sleeve 62 slotted at 63 to pass longitudinally over one or both of pins 64.

The spring 6l requires more pressure to compress it than does the spring 49', with the result that with operation of the plunger to the left in Figure 8, the operating means-not shown--will push the plunger to the left in the figure and the plunger will move bodily to the left until the contacts on the two "discs engage to close the switch. Up to this time there will be no material comprssion of spring 6I. is made overthrow of the movement oi the oper- However, after contact ating mechanism will result merely in compres.

slon oi the spring 6 I.

In the form shown in Figure 9 the shell 302 is provided with an interior shoulder 65 against which an electrically conducting `carrier in the form of an annulus 51 rests in the normal open position of the switch. This annulus is carried by a cupped mount 58', but in this case the mount 58' and annulus differ from the otherwise generally corresponding structure in Figure 8 in that the cupped mount and the annulus are not carried by the plunger in Figure 9 but are free from the plunger, as seen by the spacing therefrom at 66. They are free also to move in the shell.

Two springs are used, 61 which presses the carrier 51' to the right against the annulus and the spring 68 which is internal to the cupped mount and which is a lighter spring than is the mount spring. One end of the spring 68 is insulated by a washer. Instead of washer 60 at the cup end I may use a flat washer 60 at the opposite end. Y

The spring 68 rests against the mount at one end and, at the other end, presses a movable carrler in the form of disc 69 which is mounted between two separated parts of the plunger, as is the movable disc in Figure l, but, differing from the other figures this disc 69 is in the position of the fixed discs of the other figures. It and the annulus 51 both carry electrically conducting contacts 46 and 48, respectively as do the contact parts in the other figures.

Because spring 68 is lighter than spring 61, it will compress to the point of engagement between the contacts 46 and 48 before the spring 61 begins to compress.

The arrangement of the two springs is intended to take care of overthrow or overtravel of the operating mechanism which engages the righthand end of the plunger in Figure 9, as in Figure l, and pushes the plunger to the left. When this takes place the spring 68 compresses iirst until contact is made. The disc 69 with its contact points then carries the annulus 51 with it for any overthrow movement with consequent compression of the spring 61. The electrical circuit connections are generally as they appear in Figure 1.

In Figures 10 and 1l the two-way switch is shown making contact at both ends of the switch movement. 'I'he casing or shell is generally like that in Figure 2 with some differences of dimension, by reason of which the shell is indicated as 303 and the caps as 3| and 32.`

The shell is apertured at one side at 56 and the middle conductor, adapted to be connected to either of two other conductors, as shown at 10 is brought in through this aperture and for convenience also through a nipple 1I which is fastened to the contact carrying drum 12. It will be seen that this nipple 1| acts also as a plug by which the drum 12 can be rocked by hand to clean the contacts. Engagement of the sides of the nipple against the limits of the aperture restricts the rocking movement to any desired angle.

The conductor 10 is connected by branch conductors 13 and 14 with electrically conducting carriers, discs 15 and 16, one at each end of the drum. Each of these discs carries contacts, such as 46, for engagement with corresponding contacts, such as 48, on fixed electrically conducting carriers, discs 41, connected, respectively, with conductors and 40'.

'I'he drum 12 is a mere support for the contact 7s devices and is connected with the plunger 4|2 so as to travel with it. This plunger may be uniform throughout most of its length and desirablyprojects at both ends, at one end for engagement by an operating member and at the other end for alternative engagement for the purpose of oscillation of the drum and its contacts.

The drum is spring-pressed toward the right in Figure 10 by a spring 11 so as normally to close the contacts and to hold them closed at the right-hand side of the figure. Movement of the plunger and drum to the left breaks that engagement and subsequently, if carried far enough. closes the contacts at the left in this figure.

'I'he end of the plunger is shown as of reduced diameter at 18 so as to give room for a sleeve 19 flanged at 80. This flange forms an abutment for a spring 8|. The opposite end of the spring 8| engages the interior 82 of a cap 83 which is kept from removal .from the flanged sleeve by a threaded collar 84.

The spring 8| is relatively stiifer than is spring 11 with the result that, with engagement of any suitable operating means against the cap 83, the spring 11 first yields and allows movement of the drum to the left until this movement has been stopped by closing of the circuit at the left in the ligure. Any additional travel (overtravel) of the operating means is taken care of by subsequent compression of spring 8|.

As will be seen the lost motion mechanism may be part of the plunger proper where it is introduced between separated plunger parts or may act separately as in Figure 9. The drum in Figure l0 may also be considered for some purposes as part of the plunger.

The switches shown in Figures 12, 13 and 15 are intended for operation in connection with a motor requiring an initial operating current in excess of the holding current. For this reason the switches completely close the circuit through the motor initially and subsequently break this short circuit connection but introduce a resistance to cut down the current for holding purposes before breaking the current entirely. An excellent illustration of such use of a switch is found in the cloth guider art where the motor is of plunger type, the moving part being the armature of a solenoid. Because of the excellence of this illustration such a solenoidal circuit is shown in Figure 14.. In this circuit the movable roll 85 of a pair of cloth guider rolls 85, 86 intended to bear upon the cloth at 81 is carried by a pair of swinging arms 88 whose pivot above the figure is not shown. These swinging arms form part of a cradle having a cross bar 89 which is connected through a spring 90 with a roller carrier 9| whose roller is shown at 92.

The entire cradle can therefore be shifted and released by cam 93 swinging about a shaft 94. The shaft is connected with a lever 95 in the form of a fork which is engaged by the upper end 86 of a solenoid armature 91, the solenoid for which is shown at 98.

The solenoidal armature passes through the solenoid winding at 99 where it is connected with the plunger |00 of one of my switches |0|, by links |02 fixed to one of the connected parts and having connection with the other through a pin |03 operating in a slot |04.

Shifting now to Figures 12 and 13 and to the switch there shown, the plunger |00 is rigidly connected with a carrier |05 having thereon contacts 48 to engage with contacts 46 on a carrier |06. The carrier |05 is shown as of the general type oi' cupped carriers shown in Figures 8 and 9. The carrier |05 is downwardly pressed by spring |01 acting against cap |08 of casing |08'.

The plunger |00 is split into three parts, an upper insulation section |09, an intermediate resistance section ||0 and a lower insulation section projecting through below the bottom of the casing. The parts are joined by screw l2 on the upper section screwing into the intermediate section and screw ||3 on the intermediate section screwing into the lower section.

'I'he resistance section 0 is electrically connected at all times with the cupped carrier |00 and is in slidable connection at its lower end with the stationary carrier |06 unless disconnected by far-enough upward movement of the plunger |00, that is unless lifted to a position somewhat higher than in Figure 12. The resistance section ||0 is provided at its lower end with a ring ||4 of good electrical conductivity which makes and breaks contact with a corresponding ring I5 in good electrical engagement with the carrier |06. with the purpose and intent that when the contacts of the two carriers are together the circuit shall be closed at this point substantially without resistance, but, that with upward movement of the plunger, as the contacts of the two carriers are separated the resistance ||0 is interposed in the circuit and is maintained in this circuit until the upward movement of the plunger has proceeded far enough to break the engagement between the two rings or collars.

The electrical circuit is shown as passing from a source of current ||6 through the solenoid 98, thence from the solenoid by conductor ||1 to the cupped carrier |05, from it either directly through the contacts or else directly through the resistance ||0 to the carrier |06 and from it through conductor |8 back to the source of current.

The plunger as shown will be lifted finally to break the circuit altogether, i. e., to lift the plunger to a point where the two collars no longer engage. This lifting is effected by usually a control element, illustrated as a rocker arm ||9 rocking about shaft |20, due to the movement to the right, as seen in Figure 12, of the rocker arm |2| rigid with the same shaft. The rocker arm |2| is itself controlled by the edge of the traveling web 81, Figure 14.

In Figure 14 the rocker arm |2| is shown as shifted and allowed to return bymovement toward and away from the observer of feeler arm |22 pivoted at any suitable point. In the illustration this pivot point would lie back of the solenoid.

Illustration of the operating mechanism is not intended to be restricted to the construction shown but to comply with the statute that one operative construction be shown.

The construction in Figure 15 is intended to be eective for the same purpose as that in Figure 12 and intended to be capable of operation by similar means.

The plunger |00 carries the lost motion link plates |02, as in Figure 12, with slots |04 for pin |03. The shell |08 and cap |08' may be substantially the same as in Figure12. The con. tact carriers |05' and |06 perform the same function of making or breaking contact and are pressed, |05 toward |06, by a spring |01.

One marked difference between the structure of Figure12 and that of Figure 15 s that the resistance in Figure 12 is self-contained, i. e., is located within the switch itself. whereas in Figure 15 the resistance ||0' is indicated as located wholly outside of the switch.

The carrier |05' is a friction fit upon the plunger and in the wholly closed positionv of the switch shown engages an electrically conducting ring or sleeve ||4' which is electrically connected through resistance H0' with the carrier |06. When upward movement of the plunger begins, carrier separates from carrier |06. The circuit is not then interrupted but is completed through the resistance.

Upward movement of the plunger may be con` tinuous-for some uses, where the interval of time thus provided during which the resistance is included proves suicient and where all of the movement is to be eiected by the same means; but in the cloth guider use shown the initial movement of the plunger is effected by the solenoid and the resistance is intended to be kept in the circuit until feeler nger actuation causes the plunger to move the rest of the way. It therefore moves in two steps, the first separating the carriers and the second lifting the plunger free from electrical connection with carrier |05 to open the circuit. Stops |23 limit upward movement of the carrier |05 so that with upward plunger movement, when the carrier |05 meets the stops it becomes stationary.

When the plunger again moves, it passes through the carrier to a point where the sleeve ||4' ceases to engage the electrically conducting carrier |05 and the circuit, which intermediately has been completed when the outside resistance ||0 is broken.

In the lower part of the plunger |00 I show the lost motion mechanism as comprising a spring |24 stiffer than the spring |01 and a sleeve |25 fastened to one of the parts and slotted at |26 to pass over the ends of a pin |21 in the other part. The sleeve guides and laterally supports and the spring yields to take care of operating overtravel.

The condenser |28 is thrown across the two carriers, Figures 12 and 15, so as not only to quench the arc when the circuit is opened but to act as a capacitor also, charging and discharging when the circuit is closed and opened, increasing the power and permissible number of operations per minute of the solenoid or other motor.

In Figure 16 carriers 44 and 41 are shown as movable and fixed carriers respectively. The movable carrier is held between two parts of a plunger 4| as in Figure 2. The contacts 46 and 48 engage properly in closed switch position of the parts.

'Ihese carriers are regarded as effectively ldiscs and annuli just as are the carriers in Figures 2 and 8 for example, notwithstanding that in Figures 8 and 16 the supporting electrical conducting material forming the carriers is not iiat as in usual discs and annuli.

It will be evident that with a normally closed switch a single spring only is needed. One simple construction is seen in Figure 2. Reasonable overtravel of the operating means makes no difference. Where there is a normally open switch, however, provision for overtravel of the operating means is desirable if not essential. It can be provided either in the operating mechanism itself or by lost motion in the plunger unit, this resilient lost motion offering greater resistance to compression than does the spring between the carriers.

In all of the forms shown the contact carriers can be oscillated with opposite contacts in engagement to clean the contacts. This appears .very fully in the forms of Figures 2, 8, 9, v1|) and 16, but is not so obvious in Figures 12 and 15. In these two figures what have been called slotted plates |02 are preferably in fact U-shaped yokes having the bends of the yokes at |29 swiveled by pins |30 extending into the ends of plungers |00 and |00 so that without altering the positions of the yokes carrying these plates |02 the plungers can be engaged at their lower ends to oscillate the plungers with the contacts in closed position cleaning the contacts 46 and 48 eiectitvely, as' in the other gures. The amount oi oscillation is, as in the other ilgures, dependent upon the play allowed in the electric wiring and subject to any means which may be thought desirable for limiting angular movement.

It will be evident that the two way switch of Figures and 11 presents the characteristics of both of the switches of Figures 2 and 8 in that the switch is normally closed at one end and is normally open at the other end. The extent of throw before the normally open contacts are closed may be made suilicient so that with short throw operation to the left the normally closed switch at the right may be opened without closing the normally open contacts at the left of Figure 10, using the switch as a single throw switchor the second set of iixed contacts, at the left need not be Wired up resulting in the same single throw type of operation. -With stroke of the operating mechanism equal to or greater than that necessary for closing of the switches at the left, this switch of Figure 10 becomes effective as a double throw switch.

The operation of the structure oi Figures 12 and will be described in connection with the solenoid and the special operating mechanism shown in Figure 14 as a convenience but with the thought that the switches are of value in any location where a three position switch is needed which gives short-circuiting contact in one position, opening of this contact with interposition of a resistance between the contacting parts for a second position and a wholly open circuit in the third position.

When the main switch-not shown-controlling the supply of current to the switches in question is turned on, in this case applying current through the switch to the solenoid, the contacts upon the carriers are closed because the springs |01 and |01 have pressed the switches to full closed positions. As a result the voltage available is connected to the solenoid coils, lifting the solenoid armature 99 or 99 and lifting the pins |03 from some position well down in but above the bottom o! the slots |04/to a point above the previous upper end of the slots so that the pins |03 engage the upper ends of the slots and lift the plungers to a point such as shown in Figure 12 where the contacts no longer engage. This breaks the short-circuiting closure of the switches and, with either switch, opens it to a point suilicient to introduce the resistance I0 or I0', but not suiiicient wholly to interrupt the circuit.

The resistance ||0 or ||0' is made suiiicient to cut the current down to that which is desirposition in Figure 15 and the contacts are shown in intermediate position with the resistance interposed in the circuit in Figure 12.

When the solenoid has been energized and during its holding action (Figure 14) the tilting and holding of cam 93 presses the movable roll I5 (resiliently, by reason of the spring) toward the xed roll 86 with the cloth 81 between.

The grip of the rollers causes the cloth to be drawn toward the observer, causing the feeler nger |22 to push lever |2| toward the observer, lifting the plunger control element, the rocker arm H9 and thereby lifting the plunger as in Figure 12 to a point where the circuit is broken altogether.

When the circuit opens the solenoid armature drops, releasing the bite of the roll upon the travelling web 81, permitting the web 81 to retract (away from the observer in Figure 14). This in turn permits downward movement of the control element ||9 with corresponding downward movement of the plunger 00. It will be understood that the drop of the solenoid armature to its low position does not itself directly affect the position of the plunger |00 which continues to be held up by the control element l0 until the control element moves downward in response to inward movement of the travelling web.

As the web 81 moves inward, the plunger control element IIB moves downward with corresponding downward movement of the plunger 00 and carrier |05, closing the resistance connection between the contact carrier members |05 and |06 (Figure 112) somewhat before the plunger |00 and its contact carrier |05 are in their intermediate position of Figure 12.

Closure of the contact causes energization of the solenoid through the resistance H0, but because of proper selection of the resistance with respect to the characteristics of the solenoid, the energization of the solenoid is inadequate to lift the solenoid armature until the downwardly moving plunger brings direct engagement between the contacts 48 and 46, when the increased energization of the solenoid from bypassing the resistance ||0, lifts the rsolenoid armature to repeat the cycle as already described.

There is a slight difference in operation between the structures of Figures 12 and 15.

On the upward armature-actuated partial stroke of the solenoid the movable carrier |05 and the plunger travel together to a point where the resistance section of the plunger is interposed between the two carriers but the circuit is not broken. When the plunger is lifted further in response to feeler finger actuation both the movable carrier and the plunger lift to a point where circuit is opened.

In the corresponding movement for Figure 15 the plunger and movable carrier lift together by reason of the solenoid armature movement. This movement may continue not only until the movable carrier reaches the stops but until there has been partial travel movement of the plunger within the movable carrier, just so the contact carried by the plunger has not electrically separated from the movable carrier. In the second part of the stroke, feeler actuation lifts the plunger suiiciently to break the electrical engagement between it and the movable carrier.

In the form of Figure 15 on the downward stroke the iirst downward movement of the plunger causes the plunger-supported movable carrier to electrically engage through the contacts the flxed carrier. This takes place before the circuit is completed. Subsequently the fixed carrier acts as a stop for movement of the movable carrier and the plunger continues its movement through to a point where the electrically conducting ring or sleeve upon it engages with the movable carrier completing the circuit through the contacts 46 and 40.

It will be evident that the sleeve or collars Ill, H5, and lll' should be made of good conductors of electricity such as silver or copper and that oxidation may be prevented-for example by light chromium plating-if the advantage from chromium plating warrent the reduction in current carrying capacity in any installation.

In view of my invention and disclosure variations and modiiications to meet individual whim or particular need will doubtless become evident to others skilled in the art to obtain part or all of the benefits of my invention without copying the structure shown, and I, therefore, claim all such in so far as they fall within the reasonable spirit and scope of my invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A multiple contact plunger switch comprising a longitudinally movable plunger, a pair of electrically conducting contact carriers, one fixed and the other supported by the plunger, contacts mounted upon the carriers, a plurality upon each of the carriers adapted to interiit those upon one carrier between those upon the other carrier and to provide multiple parallel electrical connections between the carriers when the contacts of one carrier engage those of the other carrier, a casing about the carriers and plunger, connections from the carriers to the outside of the casing and a spring about the plunger pressing the movable carrier toward its normal position and normally positioning the switch in its normal position.

2. A multiple contact plunger switch comprising a longitudinally movable plunger, a pair of electrically conducting contact carriers, one fixed and the other supported by the plunger, contacts mounted upon the carriers, a plurality upon each of the carriers adapted to interiit those upon one carrier between those upon the other carrier and to provide multiple parallel electrical connections between the carriers when the contacts of one carrier engage those of the other carrier, a casing about the carriers and plunger, connections from the carriers to the outside of the casing and a spring about the plunger pressing the movable carrier toward its normal position and normally positioning the switch in its normal position, the plunger being free to rotate, to permit scouring of the contacts, those of one carrier against those of another.

3. A multiple contact plunger switch comprising a longitudinally movable plunger, a pair of contact carriers, one fixed and the other supported by the plunger, contacts mounted upon the carriers, a casing about the carriers and plunger, connections from the carriers to the outside of the casing and a spring about the plunger pressing the movable carrier toward the fixed carrier and normally closing the switch, the plunger being rotatable and the spring being anchored at both ends in fixed and rotatable parts to limit rotation and to return the plunger rotarily by the spring.

4. A multiple contact plunger switch comprising a longitudinally movable plunger, a pair of contact carriers, one fixed and the other supported by the plunger, contacts mounted upon the carriers, a casing about the carriers and plunger, connections from the carriers to the outside of the casing and a spring about the plunger pressing the movable carrier toward the fixed carrier and normally closing the switch, the plunger being rotatable and the spring being anchored at both ends, with lost motion in the anchorage at one end, limiting rotation and returning the plunger rotarily by the spring.

5. A multiple contact plunger switch comprising a longitudinally movable rotatable plunger, a pair of contact carriers, one fixed and the other supported by the plunger, rounded contacts mounted upon the carriers, a casing about the carriers and plunger, connections from the carriers to the outside of the casing, a spring about the plunger pressing the movable carrier toward the fixed carrier and normally closing the switch and means for limiting the rotation of the plunger.

6. A multiple contact unit, comprising a casing, a pair of contact carriers, one fixed and the other movable and each having a plurality of contacts spaced and of curved contour and adapted to interfit the curves of the contacts on one carrier between the curves of the contacts on the other, a rotatable plunger upon which the movable carrier is mounted, a spiral spring about the plunger engaging the movable carrier, normally holding the fixed and movable contacts together and circuit connections for the fixed and movable contacts, that for the movable contacts allowing revolution of the movable contacts for cleaning engagement with the fixed contacts.

7. A multiple contact plunger switch, comprising a casing, a plunger movable longitudinally of the casing and rotatable therein, electrically conducting contact carriers, one fixed and surrounding the plunger and the other mounted upon the plunger transversely thereof, contact pins arranged annularly about the two carriers and adapted to engage in closed switch position, circuit connections for the two carriers, that to the movable carrier permitting partial rotation of the carrier, and spring means for normally holding the switch open and a second spring means, stiffer than the first, between the operating member and the movable contact carrier, permitting plunger movement subsequent to closing of the contacts.

8. A multiple contact plunger switch, comprising a casing, a plunger movable longitudinally of the casing and rotatable therein, electrically conducting contact carriers, one fixed and surrounding the plunger and the other mounted upon the plunger transversely thereof, contact pins arranged annularly about the two carriers and adapted to engage in closed switch position, circuit connections for the two carriers, that to the movable carrier permitting partial rotation of the carrier, and spring means about the plunger adapted to hold the switch normally open and a lost motion terminal upon the plunger comprising a spring about the plunger, an abutment for the spring, a cap about the spring and means for retaining the cap.

9. A multiple contact plunger switch, comprising a casing, a plunger movable longitudinally of the casing and rotatable therein, electrically conducting movable contact carriers, one mounted about the plunger and the other mounted upon the plunger transversely thereof, a stop for the carrier about the plunger, holding it away from the position of rest of the other carrier, contact pins arranged annularly about the two carriers and adapted to engage in closed switch position, circuit connections for the two carriers, one connection permitting partial rotation of one of the carriers, spring means about the plunger pressing the carrier about the plunger against its stop and weaker spring means pressing the two carriers apart.

10. ln a device of the character stated, a casing, fixed and movable switch contact carriers normally spring pressed toward closure, a plunger upon which one of the carriers is mounted and with respect to which it can move, stops limiting the movement of the movable carrier, a contact upon the plunger engaged by the movable carrier in one plunger position and disengaged therefrom in another plunger position, a resistance connected electrically between the contact and the fixed carrier and outside the plunger, and successive means for moving the plunger, first to disconnect the contacts so that the circuit passes through the resistance and then to open the circuit.

11. In a device of the character stated, fixed and movable contact carriers, Contact elements supported by the carriers, a plunger upon which one of the carriers is mounted and can move, a spring pressing the movable carrier in a direction toward closure, stops engaged by the movable carrier, a Contact carried by the plunger engaged by the movable carrier in one plunger and electrically disconnected therefrom in another plunger position, a solenoid, a lost motion connection between the solenoid and the plunger and a resistance between the contact and the movable carrier.

l2. A multiple contact plunger switch comprising a longitudinally movable plunger, a pair of electrically conducting contact carriers, one fixed and the other supported by the plunger, multiple contacts mounted upon each of the carriers, the contacts of one carrier being adapted to mate with those of the other carrier, a casing about the carriers and plunger, connections from the carriers to the outside of the casing, a spring about the plunger pressing the movable carrier away from the fixed carrier, normally holding the switch open and a second spring stiffer than the first in the line of operation of the plunger.

13. A multiple contact plunger switch, comprising a casing, a plunger movable longitudinally of the casing and rotatable therein, electrically conducting contact carriers, one fixed and surrounding the plunger and the other mounted upon the plunger transversely thereof, contact pins arranged annularly about each of the two carriers and adapted to engage the pins on one carrier with those on the other carrier when in closed switch position, circuit connections from the two carriers, that to the movable carrier permitting partial rotation of the carrier, and spring means about the plunger adapted to hold the switch normally open.

ROBERT HE'I'HERINGTON.

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