US2747395A - Sequentially operated washing machine - Google Patents

Description

May 29, 1956 R. R. cANDoR SEQUENTIALLY OPERATED WASHING MACHINE 2 Sheets-Sheet 1 Original Filed Oct. 4, 1946 INVENTR. n @1351er CNDOR May 29, 1956 R. R. cANDoR SEQUENTIALLY OPERATED WASHING MACHINE Original Filed Oct. 4, 1946 2 Sheets-Sheet 2 x THESE F/LL PER/ons MA Y BE sHo/vTE/vfp To Sgo/r Ig? EN TOR. afrreuLAR TIME BY msi/v6 E/T- ,MyDD/L SWITCHES Y 0R Z RESPECT- IVEL).l

@MEQ-MSW nited States Patent f" SEQUENTIALLY OPERATED WASHING MACHINE Robert R. Candor, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Original application ctober 4, 1946, Serial No. 701,116. Dgi'ided and this application June 29, 1951, Serial No. 2 ,402

7 Claims. (Cl. 68-12) This application is a division of my co-pending application S. N. 701,116, filed October 4, Y1946, which is now abandoned.

This invention relates to domestic appliances, and more particularly to automatic clothes washing machines.

An object of this invention is to provide an automatic clothes washing machine capable of normal use with full batches of clothes, and adjustable to modified automatic operation with smaller batches of clothes.

Another object of this invention is to provide an automatic washing machine which operates normally with a full charge of liquid for washing a normal charge of clothes, and which operates automatically with a smaller amount of liquid for use with a fractional batch of clothes.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. l is a diagrammatic side elevation, partly in vertical cross-section, of a washing machine embodying my invention;

Fig. 2 is a diagrammatic representation of the timer used in the washing machine, together with its connections to the elements controlled by the timer;

Fig. 3 is a wiring diagram of the washing machine shown in Figs. 1 and 2;

Fig. 4 is a diagram of the dial handle on the timer, and indicates the contacts which are opened and closed at various intervals of time; v

Fig. 5 is a diagrammatic representation of the timer motor.

Automatic washing machines are iilled with clothes to be washed, and then a timer is set to control the washing machine automatically. The washing machine is automatically filled with washing liquid to a normal level, then agitation and centrifuge periods of time are established. This cycle of operations is repeated once or twice with clear water to rinse the clothes, and then the washing machine and its timer automatically stop. Such operation, in a domestic washing machine, consumes approximately 30 or 40 gallons of water, a substantial amount of soap and approximately 45 minutes of time. Consequently, it has not been considered economical or desirable to use the washing machine with a small batch of clothes, such as a collection of stockings or colored clothes, or a small emergency washing. According to this invention, however, the washing machine may be adjusted to operate with a reduced amount of washing liquid, with or without a reduced period of time for agitation and centrifuging. Thus the operator may place the fractional collection of clothes in the machine, make the necessary adjusting setting of the timer, and start operation of the washing machine. Thereafter the machine automatically washes the fractional batch of clothes with a reduced amount of liquid, with or without reduced periods `of time for agitation and centrifuging.

Patented May 29, 1956 Figs. l through 5 of this application disclose a washing machine in which the tub may be selectively filled with fractional amounts of liquid, with the washing and centrifuging periods of time maintained normal.

Brieliy described, the washing machine includes a centrifugal basket 50, having an outer imperforate tub 50a and an inner perforate tub Stlb. The basket 50 may be centrifugally rotated to dry the clothes. An agitator 51 may be placed inside of the basket, for agitating the clothes. The basket Sli and agitator 51 are actuated by power means such as transmission 52 which is actuated by a motor 53, the transmission being controlled by a solenoid 54 inside the casing of the transmission and electrically controlled by the timer. When the motor 53 is energized, together with the solenoid 54, the agitator is not reciprocated; but the tub 50 is centrifugally rotated at a sufiicient speed to wring the clothes. When the motor 53 is energized, while the solenoid 54 is deenergized, the agitator 51 is reciprocated. When the solenoid 54 is deenergized while the tub is rotated, a braking action is applied to the tub A5l), to stop it quickly. Any type of motor and transmission may be used for accomplishing this purpose, such, for example, as indicated in the application of Kendall Clark, S. N. 511,515, tiled November 24, 1943, and issued on June 17, 1947, as Patent No. 2,422,395 for Domestic Appliance.

An access door 56 is provided in the cabinet 55 for introducing the clothes and detergent into the tub 50. A door switch 57, hinged at 18 and closing contacts 17, is actuated by the rod 58 so` that the contacts 17 are opened whenever the door 56 is opened, and Vice versa. This switch prevents centrifugal operation whenv the door 56 is open.

A timer is provided, which controls the flow of electrical power from lines L1 and L2 to the various electrical elements of the washing machine.

Normally, for a full batch of clothes, the washing machine is iilled with water to the level 50c from the'hot water connector 6i) with or without water from the cold water connector 59. When the timer is adjusted to modilied operation, the liquid is introduced to some other level, such as 50d, and the machine operates normally except for the lower level of liquid.

The connectors 59 and 60 discharge into a thermostatic-mixing valve 61. The hot water connector 60 also discharges into a hot water line 71. The mixing valve 61 discharges into a mixed water line 72. The lines 71 and 72 are controlled by solenoid valves 63 and 62 respectively, and discharge into a common outlet chamber 64. This chamber is connected by line 73 to a constant pressure valve 65, which maintains a constant pressure of water in the line '74, which in turn discharges through a fixed orifice 66 and a nozzle 67 at a constant flow rate into the tub 50. The arrangement is such that the timer 70 opens the selected solenoid valve 64, 63 for a suiicient length of time so that the constant volume discharge of water at the nozzle 67 fills the tub 50 to the correct level during each iilling operation.

The position of handle 87, of the two-way selector switch 88 determines whether the movable contact S9 of the switch 8S contacts 15 or 16. When the handle 87 is on the indication I-lot, contact 89 engages 15, and the hot water solenoid 63 is energized for the first filling operation. During the second and third filling operations, the mixed water solenoid 62 is energized regardless of the position of contact 39.

Figs. 2 through 5 show details of the timer construction diagrammatically. The timer includes a timer motor 20 which moves a small gear 21 intermittently, such as at one-half minute intervals for normal operation. This movement is obtained by a gear construction, in gear box 21a, as disclosed in the patent to Hall, No. 2,227,133, patented December 31, 1940. The motor 20 has a shaft 20a, which is rotated at selected synchronous speeds, determined by the energization of the normal winding 20h, or of the fractional windings 20c or 20d. When the fractional windings 20c, or 20d, are energized, then the small gear 21 is actuated, through the same arcs, but at onethird or one-sixth minute intervals respectively. The gear 21, in turn, actuates a larger gear 22, which, in turn, is xed to a rotatable shaft 23 which actuates the control contacts. Thus, by selectively energizing one of the windings 20b, 20c, or 20d, the shaft 23 is automatically rotated, intermittently, at relative speeds corresponding to l, 3/2 and 3 respectively. The intervals of time established by the winding 20b are normal periods of time, while the periods of time established by the windings 20c and 20d are two-thirds and one-third respectively shorter than the normal periods of time. It is to be understood that the specific fractional times hereing given are merely illustrative, and may be varied as desired.

For the purpose of selectively energizing the windings 2Gb, 20c or 20d, to vary the liquid load, a switch handle 100 is provided, which actuates the switches Y and Z inside of the switch box 101. When the handle 100 is in its central (Full) position, then the switches Y and Z are both open, and do not contact the lines 102 and 103. The timer runs at normal speeds, under these conditions,

and iills the tub 50 to its full, normal level (Fig. 3).

When the handle 100 is in the Two-thirds position, then the double switch Y is in contact with the lines 102 and 103, thus establishing circuits through the lines 104 and 105, to fill the tub 50 two-thirds of normal, as later described. When the handle 100 is in the Third position, the double switch Z is in contact with the lines 102 and 103, thus establishing circuits through the lines 106 and 107 to lill the tub 50 one-third of normal, as later described.

Thus, when the handle 100 is in the Full position (with the switches Y and Z vertical and open in Fig. 3), the solenoids 108, 109, 110 and 111 cannot be energized, and the bridge contacts 112 and 113 are in their lower positions, thus establishing a circuit through lines 114, contacts 115, 116, 117, 118 and line 119, through normal winding 20h, and line 48 to L2. Under these conditions, the timer motor shaft 20a runs at normal speed.

' When the handle 100 is in the Two-thirds position, the double switch Y is in contact with the lines 102 and 103, thus establishing circuits through solenoids 108 and 109 and raising bridge 112 (whenever the lines 43 and 90 are energized to open the water lines). This establishes a circuit through the motor winding 20c, starting from line 114, 120, 121, 112, 122, 123 through clockwinding 20c thence through line 48 to power line L2. Thus, whenever the contacts 7 or 10 are closed, and switches Y are closed, then the timer winding 20c is energized, and the timer shaft 20a operates at 3/2 the speed as compared to its operation when the normal winding 20b is energized, during the filling operations to ll the tub two-thirds full.

When the handle 100 is in the Third position, the double switches Z are closed upon the lines 102 and 103, as indicated in full lines in Fig. 3. Under these conditions, the solenoids 110 and 111 are energized whenever the lines 43 and 90 (to be later described) are energized by closing contacts 7 or 10. This establishes the circuit shown in full lines in Fig. 3, and the clock-winding 20d is energized by a circuit starting with 114, 124, 113, 125, 126 through winding 20d, line 48 to power line L2. When the winding 20d is energized, the timer motor shaft 20a `-operates at three times the normal speed during the filling 'operation to fill the tub one-third full.

A timer motor capable of producing multiple speeds yin its shaft 20a, is diagrammatically illustrated in Fig. 5.

tively, are provided for these rotors. The stators preferably are provided with an appropriate number of shaded and unshaded poles to produce, for example, 1200, 1800 and 3600 R. P. M. in the shaft 20a respectively. While only one pair of shaded and unshaded poles have been shown in each instance for the sake of clearness, it is understood that the windings 20b, 20c, and 20d, may energize 3, 2 and l pairs each of shaded and unshaded poles.

The multiple speed timer motor 20 rotates the shaft 23 intermittently at selected speeds. When the handle is at Full position, the shaft 23 rotates at its slowest speed. When the handle 100 is at Two-thirds, the shaft 23 rotates at 3/2 the normal speed, and when the handle 100 is at Third position, the shaft 23 operates intermittently at three times the normal speed.

The length of any of the lill periods indicated at X is normal, two-thirds or one-third, depending on the position of handle 100 (switches Y and Z), being twothirds or one-third only when either the contacts 10 and 11 or the contacts 7 and 8 are closed and the switch 89 is either on 15 or 16 to establish fill periods. Therefore, if the handle 100 is in the Full position, the solenoids 108 through 111 cannot be energized, since the switches Y and Z are open. This causes normal operation of the timer. However, if either of the switches Y or Z are closed, the corresponding solenoids 108 through 111 are energized, from the lines 90 or 44, to rotate the timer at three-halves or three times the speed, thus shortening the till periods X to two-thirds or one-third the time.

The shaft 23 operates the timer contacts to produce iilling, agitation and centrifuge periods of time as follows: The shaft 23 carries a plurality of rotatable cams 24, 25, 26 and 27, which are in engagement with movable blades 28, 29, 30 and 31, respectively, and which carry movable contacts 6, 4, 11 and 8, respectively. The cams 24, 25, 26 and 27 have been indicated by dotted circles; but it is understood that they actually are irregularly-shaped cams so shaped that the movable contacts 6, 4, 11 and 8 are actuated at selected intervals of time, as indicated in Fig. 4. Fig. 4 shows the indications on the knob 36, which arer inside of the circle 35. The numerals on the outside of circle 35 are not placed on the knob. They are merely charts to indicate the positions of the movable contacts at the various intervals of time, as the shaft 23 is rotated intermittently clockwise. The plus signs indicate closed contacts, and the negative sign indicates open contacts.

The knob 36 is provided with an irregular orilice 37 which tits over the irregular end 38 of the shaft 23. The knob 36 is axially secured to the shaftv 23 so that, when the knob 36 and shaft 23 are moved slightly axially, a movable contact 2 is moved into and out of contact with stationary contact 1. The movable contact 2 is carried by a movable blade 39, which has its upper end in axial engagement with the shaft 23. Whenever the knob 36 is pulled toward the operator, the contacts 1 and 2 are opened to prevent operation of all elements of the machine. Whenever the knob is pushed away from the operator, the contacts 1 and 2 are closed to allow energization of appropriate elements of the machine.

A suitable snap-acting mechanism is provided for allowing the shaft 23 to be placed in these two axial posi- This may ltake the form of double-grooved ring 40, carried by the shaft 23, in which a spring-pressed pin 41 rides, so that the ring 40 snaps from one position to the other.

Whenever the movable contact 8 engages contact 9, the transmission solenoid 54 is energized, so that the tub 50 is centrifugally rotated. However, since the switch 57 is open whenever the door 56 is open, the solenoid 54 cannot be energized with the door open. Therefore, should the operator open the door while a centrifugal action is taking place, the solenoid 54 would be deeneratrasos gized and the centrifugal action would be changed to agitation. Also, if the door 56 should be left open during any previous operation, then, when the timer reaches a spin position, the solenoid 54 cannot be energized, and the tub 50 is not rotated.

When 8 contacts 7, one of the water solenoids 62 or 63 (depending on the position of switch 89) is energized and hot or tepid water is introduced into the tub. When 11 contacts 10, the mixed water solenoid 62 is energized and mixed (tepid) water is introduced into the tub regardless of the position of 89. When 11 contacts 12, the running winding of motor 53 is energized. When 3 contacts 4, the timer motor 20 'is energized. When 5 contacts 6, the starting winding of motor 53 is energized. All of the above energizations are dependent on the knob 36 being manually pushed in to close contacts 1 and 2.

In the operation of the device shown in Figs. 1 through 5, the door 56 is opened and clothes and detergent are placed in thetub 50. The door 56 then is closed, and the knob 36 is pushed in away from the user to close contacts 1 and 2, and the knob 36 is turned clockwise from the off position S (where the timer previously had stopped) to the start position A. Just before reaching the position A, 4the cams are actuated so` that contact 3 closes on 4 and contact 7 closes on 8 as indicated at A. At A, current tiows from L1 through 1, 2, 42, 31, 8, 7, 43, 89, 15, 44, 63, 45 and L2. This energizes the hot water solenoid and starts the iow of water into the tub 50. (lf 89 was in contact with 16, then the tepid water solenoid 62 would be opened instead.) At the same time, current Hows from L1 through 1, 2, 46, 3, 4, 29, timer motor 20, 48 and Lz, thus actuating the timer motor 20. The speed of rotation of the timer motor shaft 20a is determined by the position of the switch handle 100, the current flowing from 29 selectively through one of the lines 119, 123 or 126, as previously described, depending on the position of switch handle 100 to the windings 2Gb, 20c or 20d, thus causing the fill period of time to be normal, two-thirds or one-third of the normal time. The shaft 23, and knob 36 are then intermittently progressed from position A to position B (at normal, two-thirds or one-third periods of time) where contact 8 is moved away from 7; 6 is moved to 5; and 11 is moved to 12. This energizes the starting coil of motor 53 from L1, 1, 2, 46, 49, 5, 6, 28, 80, 53 and 81 to L2. It also energizes the running coil from L1, 1, 2, 82, 30, 11, 12, 83, 53, 81 and L2. The motor 53 is therefore started and caused to run on the starting and running windings thereafter. Since the transmission solenoid 54 is deenergized, the agitator 51 is agitated during an agitation period ot' time, which is normal regardless of the position of handle 100.

The timer motor 20 runs at normal speed during the agitation period because the ll electrical lines 43 and 90 are deenergized during the. agitation period, and thus the solenoids 108, 109, 110 and 111 cannot be energized, thus causing current for the timer motor 20 to ow from 11d through 115, 113, 116, 117, 112, 118 and 119 to normal winding 2011. After a suitable interval of time, as at C, the starting winding of motor 53 is deenergized by opening contacts 5 and 6. The washing operation continues (agitator action) at normal speed for the selected number of minutes, until the position D is reached. Should the user desire a shorter washing period than ten minutes indicated on the timer, he may advance the knob 36 manually clockwise to a shorter period, suchl as to 8, 6 or other minute periods.

When position D is reached, contacts 5 and 6 are closed as are also 8 and 9. The closing of contacts 8 and 9 energizes spin solenoid S4, if the door 56 is closed, and start-s the tub 50 to spin. The starting winding of the motor 53 is again energized by the closing of contacts 5 and 6, because acceleration is necessary, and the motor is slowed down by lthe weight of the tub, liquid and clothes to a speed requiring the starting winding to aid in gettingv the tub up to speed. The circuit to solenoid S4 is from L1 through 1, 2, 42, 31, 8, 9, 84, 18, 57, 17, 85, 54, S6 and L2. However, -should the door 56 be opened while the spinning operation progresses, or if the door had been left open, then no spinning of the tub can take place, since the solenoid 54 cannot be energized, because the switch 57 is open. If the tub is spun, the water in it is discharged over the rim ofthe tub into sump 200, and thence through pipe 101, pump 102 to the sewer drain connector 103. As Vthe timer continues to rotate, (on normal winding 2Gb, regardless of the position of handle 100), the position E is reached where the starting windingis deenergized by the opening of contacts 5 and 6. When the position F is reached, contact 8 is moved from 9 and 11 from 12. This deenergizes solenoid 54, and the running winding of the motor 53, and stops the spinning operation.

At position (3, 10 is closed on 11, and a fill period is started. The till period is normal, two-thirds or onethird, depending on the position of handle 100, thus lling the tub 50 to normal, two-thirds or one-third of its normal height, respectively'. Current iiows from L1 through 1, 2, 82, 30, 11, 10, 90, 62, and 91 to L2. This energizes the mixed water solenoid 62 and starts the flow of mixed Water through the nozzle 67. The ow of water continues until position H is reached by the timer, which is the correct length of time to till the tub to the normal height 50c, the two-thirds height or the one-third height.

At H, contact 11 is moved from 10 while the contacts 5 and 6 are closed together with contacts 11 and 12. This stops the l'low of water and energizes the starting and running windings of the motor 53 and agitates the clothes in a tepid rinse water for a normal period of time, regardless of the position of handle 100. The motor 20 operates at normal speed during this time because lines 43 and are deenergized, thus preventing the energization of solenoids 108 through 111. At 1, contact 6 is moved from 5 thus deenergizing the starting winding of motor 53, the motor 53 continuing to run on the running winding. From H to .l, the agitator 51 is reciprocated.

At 1, contact 6 closes on 5 while contact 8 closes on 9. If the door 56 is closed, the tub starts to spin; but if the door is already open, then the tub does not spin. At K, the starting winding is deenergized by the opening of contacts S and 6. At L, the spinning operation is terminated by the opening of contacts 8 and 9 and 11 and 12. The water in the tub is discharged by the spinning operation as before described.

At M, the mixed Water solenoid 62 is opened by the closing of contacts 10 and 11. The filling operation continues until N is reached, when contacts 10 and 11 are opened while contacts 5 and 6 and 11 and 12 are closed. This stops the filling operation and starts the reciprocation of the agitator, the motor 53 running on both of its starting and running windings. It should be noted again that the ill period from M to N may be normal, two-thirds or one-third, depending on the position of handle 100, since the line 90 is energized during this iill period, thus making it possible to energize the proper solenoids 108 through 111, depending on the position of handle 100.

At N, an agitation period is started by the opening of contacts 10 and 11 and the closing of contacts 5, 6and 11, 12. This stops the water fill and energizes the windings of the motor 53. At 0, the starting winding is deenergized bythe opening of contacts 5 and 6.

At P, the contacts 5 and 6 are closed as are also contacts 8 and 9. This starts a spinning operation, the motor 53 running on both windings until position Q, when the starting winding is deenergized by the opening of contacts 5 and 6. At R, the spinning operation is terminated by the opening of contacts 8 and 9 and 11 and 12. It should be noted that, if the door 56 should be opened at any time during the interval between P and R, the spinning operation will be stopped.

Thereafter, the timer continues to run until the position S is reached when the contacts 3 and 4 are opened, thus deenergizing the timer motor 20. At this time, the entire operation of the device disclosed in Figs. 1 through 5 is terminated.

It is understood that in Figs. 1 through 5, the shaft 23 may also be rotated independently of the timer gear 21 by pulling out the knob to the outer position, when the gears 21 and 22 are unmeshed, thus allowing the setting of the knob 36 to any desired position.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

l. In a washing machine, a tub, rotating means to rotate said tub, agitating means to agitate articles to be washed in said tub, a connector adapted to be connected to a source of liquid, a conduit from said connector to said tub, a valve controlling the ow of liquid into said tub through said conduit, a rotatable timer means establishing a first period of time for opening said valve, a second period of time for operation of said agitating means and a third period of time for'operation of said rotating means, and means to vary the rate of rotation of said rotatable timer means to vary one of said periods of time while maintaining normal rotation to maintain normal the other periods of time.

2. In a washing machine, a tub, rotating means to rotate said tub, agitating means to agitate articles to be washed in said tub, a connector adapted to be connected to a source of liquid, a conduit from said conector to said tub, a valve controlling the flow of liquid into said tub through said conduit, a rotatable timer means establishing a `first period of time for opening said valve, a second period of time for operation of said agitating means and a third period of time for operation of said rotating means, and means to vary the rate of rotation of said rotatable timer means to vary said first period of time while maintaining normal said second and third periods of time.

3. In a washing machine, a tub, agitating means to agitate articles to be washed in said tub, a connector adapted to be connected to a source of liquid, a conduit from said connector to said tub, a valve controlling the liow of liquid into said tub through said conduit, a timer establishing a first period of time for opening said valve and a second period of time for operation of said agitating means, a selective rate changing means for said timer to cause said timer selectively to operate at a plurality of rates, and an interlocking arrangement between said valve and said selective rate changing means for rendering effective said selective control means only during the open periods of said valve.

4. In a washing machine, a tub, an electrically operated agitating means to agitate articles to be washed in said tub, a connector adapted to be connected to a source of liquid, a conduit from said connector to said tub, an electrically operated valve for controlling the flow of liquid into said tub through said conduit, a timer having electrical controls and separate circuits connecting with said agitating means and said valve establishing a first period of time for energizing and opening said valve and a second period of time for operating said agitating means, a rate changing means for said timer, and a selector switch means for selectively connecting and disconnecting said rate changing means to the separate electrical circuit connecting to said valve.

5. In a washing machine, a tub, an electrically operated agitating means to agitate articles to be washed in said tub, a connector adapted to be connected to a source of liquid, a conduit from said connector to said tub, an electrically operated valve for controlling the flow of liquid into Vsaid tub through said conduit, a timer having electrical controls and separate circuits connecting with said agitating means and said valve establishing a first period of time for energizing and opening said valve and a second period of time for operating said agitating means, a triple rate changing means providing three different rates of operation of said timer, and a three position selector switch means for selectively connecting and disconnecting said rate changing means to the separate electrical circuit connecting to said valve to provide different rates of operation of said timer during the energizing of said valve.

6. In a washing machine, a tub, an electrically operated agitating means to agitate articles to be washed in said tub, a connector adapted to be connected to a source of liquid, a conduit from said connector to said tub, an electrically operated valve for controlling the fiow of liquid into said tub through said conduit, an agitator circuit connected to said agitating means, a valve circuit connected to said valve, a timer having a first set of controls connecting and disconnecting said valve cirucit with a power source to establish a first period of time for opening said valve, said timer having a' second set of controls connecting and disconnecting said agitator circuit with a power source to establish a second period of time for operating said agitating means, first and second rate changing means providing a plurality of different rates of operation of said timer, and a plural position selector switch means having a disconnected position and first and second connected positions connecting said valve circuit selectively with the first and second rate changing means.

7. A washing machine including a clothes receptacle, a constant flow type liquid tilling device for said clothes receptacle, agitating means for said clothes receptacle, liquid extracting means for said clothes receptacle, a sequential timing means having a normal constant rate of speed for sequentially effecting operation for a predetermined timed period of the liquid filling device and of the agitating means and of the liquid extracting means, and a selective rate control means for said timing means and means interlocking said control means and said liqiud filling device and responsive only to and during the operation of the liquid filling device for increasing the rate of speed of the timing means to an increased constant rate of speed during the operation of the liquid filling device to reduce the amount of liquid delivered to said clothes receptacle without changing the period of operation of the agitating means and the liquid extracting means.

References Cited in the file of this patent UNITED STATES PATENTS 1,940,549 Jones Dec. 19, 1933 2,035,083 Mattern Mar. 24, 1936 2,254,269 Clark et al Sept. 2, 1941 2,302,923 Zimarik Nov. 24, 1942 2,331,699 Kirby Oct. 12, 1943 2,366,236 Clark Jan. 2, 1945 2,391,718 Lindemann Dec. 25, 1945 2,407,660 Graham Sept. 17, 1946 2,579,598 Morrison Dec. 25, 1951

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