US2201456A

US2201456A - Mechanical timer for toasters

Info

Publication number: US2201456A
Application number: US159880A
Authority: US
Inventors: Sardeson Robert
Original assignee: McGraw Electric Co
Current assignee: McGraw Electric Co
Priority date: 1937-08-19
Filing date: 1937-08-19
Publication date: 1940-05-21
Anticipated expiration: 1957-05-21

Description

May 21, 1940. I R. SARDESON 2,

MECHANICAL TIMER FOR TOASTERS Fglled Aug. 19, 1937 5 Sheets-Sheetl Inventor: Robert Saroleson. FtS- Z orney.

y 21, 1940- R. SARDESON 2,201,456

MECHANICAL TIMER FOR TOASTERS Filed Aug. 19, 195'? 3 Sheets-Sheet 2 L Robes-t sardeson.

B3 UV? ill t orney.

May 21,1940. R. SARDESON 7 2,201,456

MECHANICAL TIMER FOR TOASTERS Filed Aug. 19, 1957 3 Sheets-Sheet s Inventor- Robert Sardeson.

Patented May 21, 1940 MECHANICAL TIMER FOR TOASTERS Robert Sardeson, Minneapolis, Minn., assignor to McGraw Electric Company, Chicago, 111., a. corporation of Delaware Application August 19, 1937, Serial No. 159,880

1'? Claims.

mechanical timer having a wide variation in speed; to provide a variable speed timer embodyin novel means to vary the speed of operation thereof; to provide a relatively simple and compact oscillator and oscillator actuating mechanism for a variable speed timer, and to provide a relatively simple and efficient variable speed timing mechanism operatively associated with an electric toaster cooperating therewith to vary the operating period of the toaster in accordance with temperature changes of the toaster.

Other objects of my invention will more fully appear from the following description and the accompanying drawings and will be pointed out in the claims.

In the drawings,

Figure 1 is a view in vertical longitudinal section through a toaster with which is associated a View being taken on the line of Fig. 5,

Fig, 2 is a fragmentary sectional view thereof taken on the line 2-2 of Figs. 3 and 5,

Fig, 3 is a fragmentary sectional view taken on the line 3-3 of Fig. 2 and shown on an enlarged scale,

Fig. 4 is a view in vertical section, taken on the line 4-4 of Fig. 5,

Fig. 5 is a view in front elevation, with the front part 'of the outer casing broken away,

Fig. 6 is a fragmentary sectional view taken on the line 6-6 of Fig. 3,

Fig. '7 is a fragmentary view in horizontal section, taken on the line 1-1 of Fig. 4,

Fig. 8 is a fragmentary sectional view of a modified form of oscillator and oscillator actuat-' ing mechanism taken on the line 8-8 of Fig. 9,

Fig. 9 is a fragmentary view, partially in section and partially in side elevation of the parts I veloped particularly for use with a vertical oventype toaster, although its use is not limited thereto.

A toaster designated in its entirety by the numeral 2| includes a skeleton base frame 23 which may be made of a suitable molded composition material having depending supporting members 25 thereof and a metal base plate.2'|, which latter may be secured to the frame 23 in any suitable or desired manner such means being shown as including a plurality of machine screws 29 (see Figs. 1 and 4). A toasting chamber structure is supported on the base plate 21 and includes a rear intermediate plate 3|, a front intermediate plate 33. The bottom wall of the toasting chamber is constituted by the base plate 21 while the top wall thereof is constituted by a top or cover member 39 which constitutes a part of an outer enclosing casing having front, rear and side walls 4| adapted tobe supported on the base plate or the frame 23. Side walls or

baffle plates

35 and 31 are also provided within the side walls of the outer casing.

A plurality of substantially vertical extending heating elements 43 are provided, there being two such heatin elements, spaced apart a suitable distance, for each bread slice to be toasted in a toaster of this kind and it is to be noted that a two-slice toaster has been shown although this is for illustrative purposes only. A resistor strip 45 is wound on suitable sheets of electricinsulating material, such as mica, for each heating element, in a manner well known in the art. The outermost sheets of mica constitute the side walls of the toasting chamber.

Top frame plates 41 cooperate with the front and.rear intermediate walls to hold the top portions of the respective heating elements in their proper operative positions, guard wires 49 depending from the respective top frame plates to prevent direct engagement of the resistor 45 and a slice of bread being toasted.

An outer pair of vertically extending rods or standards 5| are located between the front wall of casing 4| and the front intermediate wall 33 in what may be called the mechanism chamber. A second pair of vertical standards 53 are provided intermediate the outer standards 5|, the bottom end portions of the standards being held by base plate 21 while the top end portions may be held by forwardly extending parts of the frame plates 41 and by a crossbar 55.

A carriage 51 is vertically movable on the inner pair of standards 53 while sliders 59 and BI are similarly movable on the outer pair of standards 5i. Carriage 51 has a forwardly extending arm 63 secured thereon to receive anactuating knob 65, the arm 63 extending outwardly through a suitable slot in the front wall of casing H.

A switch controlling the energization of the heating elements includes a fixed contact member 51 insulatedly mounted on the front intermediate wall 33 and a pivotally mounted switch arm 69 carried by a bracket II also insulatedly mounted on the front intermediate wall 33. Switch arm 69 is biased to open position by a bell crank lever pivotally supported at I3 on the rear intermediate wall 31 and including a short arm I5, the outer end of which is connected to one end of a biasing spring 11, the other end of which is connected to base plate 27. The bell crank lever includes also a longer arm- I9 having a slotted front end portion 8i. A crossbar 83 (see Fig. 5) is rigidly connected to the sliders 59 and SI and this bar fits into the slot in the front end portion BI whereby, when the carriage 5? bearing upon portions of the sliders is moved downwardly by an operator pressing on knob 65, arm 19 is moved in a clockwise direction to tension spring 11.

Slider 59 has secured thereto a plate having an angularly extending slot 81 therein (see Fig. 1) while switch arm 63 has a pin 83 secured thereto at its upper end which pin moves in slot 81. As plate 85 is moved downwardly the eiiect will be to cause switch arm 59 to engage fixed contact member 51 thereby effecting energization of the heating elements. A twin conductor cord 9i electrically connected to the switch and the heating elements extends outwardly of the toaster assembly through the rear wall of outer casing M and preferably through a bushing 93 of electric insulating material. The rear wall of the casing 4i may be provided with a carrying or lifting knob in a manner well known in the art.

Reference may here be made to Ireland Patent No. 2,001,362 as showing a toaster embodying substantially all of the features thus far described.

It is desired to provide a timing mechanism to control the operating period of a toaster of this kind, that is the length of time during which one or more slices of bread placed upon bread slice supports 97, which supports are secured to and movable with the sliders 59 and BI are subjected to high temperature radiant heat from the heating elements after an operator has depressed knob 55 to a lower position, in which bread slice supports 91 are near the bottom of the toasting chamber with all of the respective slices of bread positioned within the toasting chamber and where the switch is in closed position. Since the length of time required to toast a slice of bread to a given desired degree varies with the temperature of the toaster, that is the operating period of the toaster is less when a toaster is hot than when it is cold, it is highly desirable to provide a variable speed timing mechanism which shall follow the variations of temperature of the toaster so that when a user has once adjusted the toaster to obtain the degree of toasting desired, no further manual control of the timing mechanism shall-be necessary.

The duration of an operating period of a toaster of this kind has been found to vary between wide limits. Thus an operator may start with a cold toaster and may be receiving energy from a supply circuit of abnormally low voltage and the length of time required for satisfactorily toasting a slice of bread may be nearly four minutes. A toaster of this kind may be operated on abnormally high voltage until heated to its maximum operating temperature, when the operating period may be fifty-five to sixty seconds to cause sub stantially the same degree of toasting of similar slices of bread. Thusa speed range of not less than four to one is necessary in a timing mechanism used with a toaster, to insure uniform toasting of slices of bread under all operating conditions.

I provide a timing mechanism designated generally by the numeral IUI which includes two side plates I03 and I05. The timer includes also a clock spring IIII having one end connected to a fixed post I09 on outer plate I03 while the inner end thereof is connected to a spring shaft or arbor I I I rotatably supported in the side plates I03 and I05. A train of gears designated generally by I I3 in Fig. 2 of the drawings, is driven by the spring If)? after the spring has been wound up and is then permitted to unwind. In order to effect winding of the spring the spring shaft III has a spur pinion H5 thereon which meshes with a rack bar Ill, a grooved roller H9 being provided to maintain rack bar I I1 in mesh with pinion I I5. The lower end of rack bar I" is provided with a lateral lug I2I, which lug is adapted to be en gaged by a depending portion 123 constituting a part of or secured to carriage 5'l. When carriage 57 is moved downwardly as has already hereinbeiore been described, member I23 engages lug i211 to thereby move rack bar I I"! downwardly to wind up spring IIJ'i.

v Slider 6! is further provided with a portion I25 at its lower end, which is adapted to move below a detent I27 of a latch arm I29 pivotally Y mounted on side plate I 05 to thereby hold the 'switch in closed position and the bread slice supports in their toasting position.

Gear train I13 ends in a pinion ISI which pinion includes a grooved collar I33 (see Fig. 3) and which is removably mounted on a suitable stub shaft I35. A resilient bar I3? is secured to plate I05 and has its offset outer end fitting into the grooved collar I33 to hold the pinion in proper operative position substantially as shown in Fig. 3 of the drawings. A counterbalanced crank disk I39 is fixedly mounted in or on pinion I3I and carries a crank pin I II. This crank pin is adapted to be rotated in a given direction during the unwinding of spring IO'I which occurs during an operating period of the toaster. The counterbalancing of the crank disk reduces the unbalance which would otherwise occur and makes for smoother operation and less wear of these parts.

A connecting rod I43 has one end thereof pivotally connected to crank pin HI and is provided with an opening I45 intermediate its ends to receive the straight end I41 of a resilient connection, which connection includes in addition to the resilient arm I41 a helical coil I49 and a second straight and resilient end portion I5I thereby providing one major and two minor or auxiliary resilient connections between the connecting rod and the balance wheel. The helical coil portion I49 is positioned around a shaft I53 on which is fixedly mounted an oscillator comprising a cup shaped member I55 and a metal filling I51 therefor, there being a central recess I59 and a substantially radially extending recess ISI in the metal filling to receive respectively the helical part I59 and end portion I5I of the spring. The recesses I59 and IGI make it possible to use a relatively large number of turns in the coil I 49 and still have a relatively short axial extension of the resilient connection beyond shown clearly in Fig. 3 of the drawings.

one face of the oscillator. It is obvious that when pm MI is rotated the connecting bar I43 will be moved substantially longitudinally of its length and thereby cause oscillating or reciprocal rotating movement of the oscillator or balance Wheel.

It is obvious that an oscillator in the form of a balance wheel having the substantially radially extending slot I6I therein will be dynamically unbalanced and will operate unevenly at'some one or several speeds of rotative movement. In order to correct this I remove some of the filling I51 at a point substantially diametrally opposite the slot I6 I as indicated at I62 so that the balance wheel will have a constant predetermined inherent dynamic balance. Acontributing factor is that the balance wheel itself comprises no relatively movable component parts of appreciable weight, the different relative positions of which might deleteriously affect the smooth and even operation of the balance wheel, by causing the balance wheel to have a variable dynamic unbalance.

It is further desired to shift the position of rod I43 on the spring end I41 as by moving it closer to shaft I53 or farther away therefrom and for this purpose I provide an adjusting member or bar I63 which is pivotally mounted coaxially with the axis of the crank disc, as

Member I63 is provided with a lateral extension I65 at its outer end, having an opening therethrough for receiving .the outerend of rod I43 at a portion thereof slightly beyond member I41, in

order to reduce to as great a degree as may be possible in the small dimensions available, variations in the distance of the connecting rod from the axis of shaft I53 during rotation of the crank pin. Member I63 may be pivotally supported on a pin I61 in plate I03 and the outer end of pin I61 may have secured thereto an adjusting arm I69 (see Fig. 4) whereby limited turning movement of member I63 may be eflfected by means hereinafterto be described. It is obvious that a connecting rod of this kind will not have a connection with the oscillator of constant length during any one revolution of the crank pin, but that the length of the effective lever arm of the transmitted force varies during each such revolution. H v

It is of course desirable, on the part ofan operator, to vary the operating period of a timing mechanism and toaster of this kind not only to obtain light, medium and dark toast, but also to be able to properly toast different kinds of bread. For this purpose I provide a bracket "I which has slidable movement relatively to the timing mechanism, being held against outer plate I03 by a pair of headed pins I13 and I15, which pins fit in elongated slots provided in a vertical portion I11 of bracket "I. A leaf spring I19 is held by pin I to tightly but movably clamp bracket I1I in its proper operative position against plate I03. The lower portion of bracket I1I has'a part I3I extending into a slot I33 in plate I03, the inner edge thereof being provided with teeth to mesh with a pinion I35, which pinion is carried on a short rod or pin I31 extending outwardly through the front wall of casing 4I where it is provided with an actuating knob' I89 which can be turned manually to thereby move bracket I1I upwardly ordownwardly as desired. Amember I3I, ofsubstantially L-shape (see Fig. 4), is supported on bracket HI and has an upper lateral extension I93 adapted to abut against the end portion of adjusting arm I69 which may be made of rounded shape as shown in Fig. 4 of the drawings. A spring I95 biases member I69 against projection I93.

Bracket I1I supports a bimetal element I91 which may be of the kind described and claimed in my co-pending application Serial No. 127,100, filed Feb. 23, 1937, and assigned to the same assignee as is the present application. The free end of bimetal element I91 carries an arm I99, the outer end of which is adapted to engage a laterally projecting lug 20I on member I69. The

.design and construction of bimetal element I91 is such that its free end flexes downwardly with increase in temperature whereby engagement between arm I99 and lug 20I is effected when bimetal I91 has reached a certain temperature, whereby turning movement of arm I69 is effected in a clockwise direction as seen in Fig. 4 of the drawings, and connecting rod I43 is moved away from theaxis of shaft I53 to thereby reduce the braking effect of the oscillator on the timer and cause the timer to operate at a higher speed and thereby shorten the operating period of the toaster.

Figs. 4 and 7 show the location of the bimetal element I91 relatively to the toasting chamber and one of the heating elements 43. The bimetal element includes a long arm and ashort arm, it being supported at the outer end of the short arm on a part of bracket IN. The long arm is located relatively close to 'the heating element, substantially at one side of the baffle plate 31 while the short arm is located outside of the baflie plate 31, which is provided with an opening 202 to receive the bimetal element. The

long arm is thus subjected directly to high temperature radiant heat from a heating element 43 and is positioned adjacent to the toasting chamber as hereinbefore defined. I

As rack bar H1 is moved upwardly during the running-down period of the timer, lug I2I causes upwardly movement of carriage 51 by reason of its engagement with member I23 which member has a cam surface 203, (see Fig. 2) which cam surface is adapted to engage a cam follower 205 on latch bar I29 at substantially the upper end thereof. When this engagement occurs latch arm I29 is turned in a clockwise direction as seen in Fig. 2 of the drawings and therebyreleases portion I fromdetent I21 so that spring 11 may cause upward movement of the bread slice supports 91 and opening of the switch hereinbefore described.

It is obvious thatthe oscillator or balance wheel and its actuating mechanism asthus far disclosed and described is subject to a variable push or pull because of the fact that the angular position of rod I43 relative to the axis of shaft I53 varies during each revolution of the crank pin. While these variations have no harmful effects on the operation of the timer. it may be desirable to overcome this and I will now. describe a modified form of balance wheel or oscillator and actuating mechanism therefor, which is not subject to this variation and reference may be had first to Figs. 8 and 9 of the drawings. I have there shown a crank pm I which maybe driven in substantially the same manner as shown in Figs. 1 to 7' of the drawings andwhich has pivotally connected thereto a short rod 201 which is pivotally connected to a sliciabl? rod 233 having an opening 2H therein intermediate its ends to receive straight end portion II! of a spring connection of the same kind as has already been hereinbefore described. Rod 209 is supported and guided in a frame 2I3 having two bearing lugs 2I5 and 2IT each with an opening therethrough to receive a part of rod 209. Frame 2I3is pivotally supported at/one of its ends coaxially with crank disc I39. An arm 2I8, which is'the counterpart of arm I69 in Fig. 4 of the drawings, is suitably secured in fixed relation to frame 2I3 so that movement of arm 2I8 will cause swinging movement of frame 2 I3 and a variation in the distance of rod 209 from the axis of the oscillator.

The shell I and its filling I51 may be mounted on a special form of shaft 2I9, which as shown in Fig. 8 of the drawings, has its end bearing portions offset relatively to the axis of the shaft so that it is possible to move rod 209 closer to the axis of turning movement of the balance wheel I55 than would be possible if the'axis of the bear- 'ing portions were the same as the axis of the shaft. This means of course that a greater braking effect of the balance wheel or oscillator is obtainable than is possible with the structure shown in Figs. 2 and 3 of the drawings. Further, there is no variation in the distance between the rod 209 and the axis on which the oscillator turns during the rotation of the crank pin.

Referring now to Figs. 10, 11 and 12 of the drawings, I have there illustrated a still further modification in which a crank disc I39 having a crank pin Ill thereon actuates a slidable rod 22I through a short connecting rod 222, the rod 22I being caused to move parallel to its longitudinal axis by being mounted in a suitable bearing means 223, which may be fixedly supported by one of the side plates of the timing mechanism. A pin 225 is pivotally mounted on the outer end of rod 22I and has an opening therethrough to receive spring member I", so that reciprocating movement of bar 22I may cause reciprocal turning movement of oscillator I55 in substantially the same manner as is effected by the other modiflcation hereinbefore described.

The shaft I53 of balance wheel or oscillator I55 is pivotally supported as by one or more bars 221 pivotally mounted at 229 on a shaft which may be supported in one of the frame plates I03 and I85. The axis of the supporting shaft is longitudinally alined with the axis of rod 22I. An arm "I is fixedly connected with the swinging support 221 whereby, upon turning movement in a clockwise direction as seen in Figs. 10 and 11 of the drawings, the axis of the shaft supporting the oscillator may be moved relative to the longitudinal axis of slidable bar 22 I. Thus Fig. 10 shows the parts of the oscillator .in one operative position where a given amount of braking or retarding eii'ect is obtained and Fig. 11 shows the parts where substantially no braking or retarding effect is obtained since slidable bar 22I moves on the straight end I" longitudinally thereof without appreciable or any retarding eilect. Arm 2" is equivalent to arm I" of Fig. 4 of the drawings and may be adjusted both manually and thermally as was hereinbefore set forth in connection with arm I I.

Tests on a device of the kind illustrated in Figs. 1 to 7 have shown that it has a relatively high mechanical eiiiciency, is very quiet in operation, is easily adjusted for diilerent speeds and has a wide range of operating speeds, and it is to be noted that at present I prefer this form of device becauseoiitssimplicltya'ndlowercost. the

use of resiliently connected resilient arms pro- I vides one main and two auxiliary resilient elements or one major and two minor resilient elements inthe balance wheel actuating means, these elements having difierent degrees of resiliency, whereby very quiet operation of the timer is obtained.

The device embodying my invention thus provides a relatively simple, compact and easily operable timer mechanism which has been found very effective for its intended purpose. It has for instance been found that a device of the kind shown particularly in Figs. 1 to 7 of the drawings is effective to vary the operating period of a toaster from approximately fifty seconds when the toaster has been operated for some time and has reached substantially its maximum operating temperature and is also effective to provide an operating period of almost four minutes in length starting at ordinary room temperature, thereby making possible a range of over four to one in speed or duration of operating period.

It is desired to here make of record certain pertinent prior art all of which was known to applicant and which has been considered in the claims as drawn up,.to clearly define applicant's invention and to distinguish it therefrom. German Patent No. 58,196 discloses a mechanical timer having an escapement wheel and an anchor operated thereby, which anchor is mounted on a fixed pivot and has a longitudinal slotted outer arm. An oscillator in the form of a balance wheel has a pin projecting from one face thereof and fitting into the slot in the outer arm of the anchor. The balance wheel may be moved in a straight line relatively to the pivot shaft of the anchor to thereby vary the eifective length of power arm of the anchor, the length of power arm of the oscillator remaining constant.

German Patent No. 432,323 discloses a device somewhat similar to that disclosed in German Patent No. 58,196, except that the fixedly mounted anchor has a pin projecting from one side thereof on its outer arm, which pin is adapted to fit into a radially-extending slot in a pivotally mounted oscillator. The oscillator may be moved relatively to the pivot pin .0! the anchor to thereby vary the length of power arm of the oscillator while the length of power arm of the anchor remains the same.

In contradistinction to these forms the preferred form of my device provides a connecting rod acting on a resilient member connected to a stationary balance wheel and movable on the resilient member to vary the eiiective length of lever arm of the resilient member. The device illustrated in Figs. 10 to 12 provides a rod reciprocally movable in a straight line and a pivotally mounted balancewheel actuable by the reciprocable rod through a resiliently connected resilient arm, the elective length of the resilient arm being variable. Both forms of my invention provide a resilient connection to the balance wheel having a plurality of resilient portions, of different degrees of resiliency.

Various modifications may be made in the d vice embodying my invention without departing from the spirit and scope thereof and I desire therelore that only such limitations shall be placed thereon as are imposed by the prior art or are set forth in the appended claims.

I claim as my invention:

1. In a mechanical timer for causing other mechanism to operate after a time interval, a

powerdrivengeartraimacrankpinconnected 15 the connecting rod to cause the balance wheel to be reciprocally angularly rotated by the substantially longitudinal movements of said rod and means for varying the distance between the axis of said balance wheel shaft and the longitudinal axis of said connecting rod.

2; In a mechanical timer adapted to cause other mechanism to operate after a time interval, a power driven gear train, a crank pin connected therewith and rotatable thereby, a connecting rod reciprocally actuable by said crank pin through a fixed distance in a direction substantially parallel to its longitudinal axis, a balance wheel, a rotatably mounted shaft supporting said balance wheel, a coil spring surrounding said shaft and having one end portion engaging the balance wheel and having its other end portion extending substantially radially outwardly of said shaft and having a slidable and pivotal connection with said connecting rod to cause the balance wheel to be reciprocally angularly rotated by said connecting rod and means for moving the connecting rod on said radially extending end portion to vary the distance between the axis of said balance wheel shaft and the longitudinal axis of said connecting -rod.

3. In a mechanical timer for controlling the timer comprising a spring driven means connected to act on said detent to cause release thereof after a time interval and a retarding means connected with said spring for delaying release of said detent and including a gear train, a crank disc driven by said gear train and. having a crank pin thereon, a connecting rod reciprocally operableby said crank pin, a rotatably mounted bal ance wheel, an arm resiliently connected with said balance wheel and extending substantially radially of the axis of said balance wheel and slidably and pivotally connected with said connecting rod and means supported substantially coaxially with said crank disc for varying the point of engagement of said connecting rod with said arm to vary the rotative speed of said balance wheel.

4. In a mechanical timer for controlling the duration of an operating period of an automatic toaster including an electric toast heating element, a bread slice support movable into toasting and non-toasting positions relatively to said toast heating element and yieldingly biased tonon-toasting position, means to move the bread support into toasting position and a detent for holding the bread support in toasting position, said timer comprising a spring driven means connected to act on said detent to cause release thereof after a time interval and a retarding means connected with said spring for delaying release of said detent and including a, gear train, a crank disc driven by said gear train and having a crank pin thereon; an elongated connecting rod reciprocably actuable by said crank pin, a rotatably mounted balance wheel, a coil spring substantially coaxial with said balance wheel and having one end portion connected with said balance wheel and having its other end portion extending outwardly of the axis of said balance wheel and slidably and pivotally connected with said connecting rod and thermally-controlled means pivotally supported substantially coaxially with said crank disc for. varying the distance between the longitudinal axis of the connecting rod and the axis of the balance wheel and thereby the duration of said time interval.

5. A device as set forth in claim 4 in which the :luration may be varied in substantially the ratio of four to one.

6. In a mechanical timer adaptedfor mounting on an automatic toaster including an electric toast heating element, a control switch therefor, a bread slice support movable into toasting and non-toasting positions relatively to the toast heating element, means to bias the switch to open position and the bread support to non-toasting position and means to move the bread support into toasting position and the switch into closed position, said timer including a detent for holding the bread slice support in toasting position and the control switch in closed position, a spring driven means connected to act on said detent to cause release thereof after a time interval and a retarding means connected with said spring for delaying release of said detent including a gear train, a crank disc driven by said gear train and having a crank pin thereon, a connecting rod reciprocally actuable by said crank pin through a fixed distance in a direction substantially parallel to its longitudinal axis, a balance wheel rotatably mounted with its axis at one side of the longitudinal axis of the connecting rod, a substantially radially-extending arm on the balance wheel resiliently connected therewith by a coil spring and having a slidable and pivotal connection with said connecting rod and means pivotally supported substantially coaxially with said crank disc and loosely slidably engaging and partially supporting said connecting rod for moving the same to vary its point of engagement with said arm and thereby vary the duration of said time interval.

7. In a mechanical timer adapted for mounting on an automatic toaster including an electric toast heating element, a control switch therefor, a bread slice support movable into toasting and non-toasting positions relatively to the toast heating element, means to move the bread support into toasting position and the switch into closed position and means to bias the switch to open position and the bread support to nontoasting position, said timer including a detent for holding the bread slice support in toasting position and the control switch in closed position, a spring driven means connected to act on said detent to cause release thereof after a time interval and a retarding means connected with said spring for delaying release of said detent including a gear train, a counterbalanced crank disc structure rotatable by said gear train and having a crank pin thereon, a connecting rod connected to and reciprocally actuable by said crank pin through a fixed distance in directions substantially parallel to its longitudinal axis, a balance Wheel, a rotatably mounted shaft supporting the balance wheel, a coil spring loosely surrounding the balance wheel shaft and having a resilient end portion engaging the balance wheel and having another resilient end portion extending substantially radially outwardly of said balance wheel shaft, said other end portion of the spring having a slidable and pivotal connection with said connecting rod and a thermally-controlled adjusting arm for moving said connecting rod on said other end portion of the spring, said adjusting arm having one end portion pivotally supported substantially coaxially with said crank disc and having its other end portion slidably engaging and supporting said connecting rod at a part thereof longitudinally beyond said other end portion of the spring, the radial distance of the point of engagement of the connecting rod with the end portion of the spring from the axis of the balance wheel varying during each revolution of the crank pin.

8. A timer as set forth in claim 7 in which the timer includes two side plates, one of said side plates supporting a stub shaft on which said crank disc structure is loosely rotatably mounted and in which said one side plate has mounted thereon a resilient member interfitting with said crank disc structure to hold it in its proper operative position on said stub shaft.

9. A timer as set forth in claim 7 in which the timer includes two spaced side plates, one of said side plates having fixedly mounted thereon a stub shaft forsupporting said crank disc and the other of said side plates having mounted thereon said adjusting arm and the thermal control therefor.

10. In a mechanical timer adapted to cause other mechanism to operate after a time interval, a spring driven gear train, a crank disc rotatable by said gear train and having a crank pin thereon, a slidable bar, a connecting rod having one end connected to said crank pin and its other end connected to said slidable bar to cause reciprocal movements thereof along its longitudinal axis, a balance wheel, a rotatably-mounted balance wheel shaft on which said balance wheel is mounted, the axis of the balance wheel being parallel to and spaced from the axis of the shaft, a resilient arm, a coil spring connecting said resilient arm and said balance wheel, means providing a slidable and pivotal connection between said arm and said slidable bar and a swinging support for said slidable bar pivotally supported substantially coaxially with said crank disc for shifting said slidable bar on said resilient arm to vary the amount of retarding efiect provided by said balance wheel and thereby vary the time interval.

11. A timer as set forth in claim 10 and including a thermally-controlled means acting on said swinging support to cause shifting of the slidable bar in accordance with changes in temperature of the thermally-controlled means.

12. A timer as set forth in claim 10 and including a thermally-controlled means supported solely by said timer and connected with said swinging support to move the same and the slidable bar to a greater distance from the axis of said balance wheel upon increase of temperature.

13. In a mechanical timer adapted to cause other mechanism to operate after a time interval, a spring driven gear train, a crank disc rotatable by said gear train and having a crank pin thereon, a slidable bar, a connecting rod having one end connected to said crank pin and its other end connected to said slidable bar to cause reciprocal movements thereof along its longitudinal axis, a balance wheel, a balance wheel shaft on which said balance wheel is mounted, a resilient arm, a coil spring connecting said arm and said balance wheel, means constituting a slidable and pivotal connection between said arm and said slidable bar and a swingable support for said balance wheel shaft to effect movement thereof in an arcuate path to vary the distance between the longitudinal axis of the slidable bar and the axis of the balance wheel.

14. In a mechanical timer adapted for mounting on an automatic toaster including an electric toast heating element, a control switch therefor, a bread slice support movable into toasting and non-toasting positions relatively to said toast heating element, means biasing the switch to open position and the bread support to non-toasting position and means to move the switch to closed position and the bread support into toasting position, said timer including a detent for holding the bread slice support in toasting position and the control switch in closed position, a spring driven means connected to act on said detent to cause release thereof after a time interval and a retarding means connected with said spring for delaying release of said detent including a gear train, a. crank disc rotatable by said gear train and having a crank pin thereon, a slidable bar, a connecting rod having one end connected to said crank pin; and its other end to said slidable bar to cause reciprocal movements thereof along its longitudinal axis, a balance wheel, a balance wheel shaft on which said balance wheel is mounted, a resilient arm, a coil spring connecting said resilient arm and said balance wheel, means providing a slidable and pivotal connection between said arm and said slidable bar and a pivotally mounted swingable support for said balance wheel shaft for effecting movement thereof in an arcuate path relative to said slidable bar to vary the amount of retarding effect caused by said balance wheel and consequently the time interval. I

15. A timer as set forth in claim 14 and including a thermally-controlled means acting on said swingable support to cause a decrease in the retarding effect with increase of temperature of the thermally-controlled means.

16. A device as set forth in claim 7 in which the degree of movement of the connecting rod on the other end portion of the spring is such as to result in a range of duration of time interval of four to one.

1'7. A device as set forth in claim 10 in which the degree of shifting of the slidable bar on the resilient arm is such as to vary the time interval substantially four to one.

ROBERT SARDESON.