US2906328A - Timer switch - Google Patents

Description

Sept. 29, 1959 c. WANTZ 2,906,328

TIMER SWITCH Filed Aug. 1, 1955 3 Sheets-Sheet l I X IN VEN TOR. H6. 2 fimumcz Ww z.

lusmam'x Sept. 29, 1959 c. WANTZ 2,906, 328

TIMER SWITCH Filed A112. 1, 1955 3 Sheets-Sheet 2 L1 L2 H HG. 4- INVENTOR.

CZAREME WWTZ. BY M 7 jaw/W C. WANTZ TIMER SWITCH Sept. 29, 1959 3 Sheets-Sheet 3 Filed Aug. 1, 1955 INVENTOR. CZARE/VCE WANTZ H16 ATTORNEY United States Patent C) TIMER SWITCH Clarence Wantz, Los Angeles, Calif.

Application August 1, 1955, Serial No. 525,569

3 Claims. (Cl. 161-1) This invention relates to combination controls for electrical clothes dryers, and, more particularly to controls wherein a timer control switch operates upon a heater element and drum motor.

The present invention is characterized by a timer control switch which controls the energization of a clothes dryer heater element and a motor-driven shell or drum in which the clothes are loaded for the drying operation which results when heated air is circulated through the load by the rotating drum.

In the present invention, the heating element and the drum motor are connected in a circuit with a timeregulated switch. A detent mechanism is interposed between the switch and the timer for controlling the interval of time during which the heater element and the drum motor are energized. The drying cycle of the heater element is initiated by the actuation of a single control knob to any desired time setting. At the termination of the time interval, the heater element is deenergized but the drum motor continues to operate until the expiration of a second predetermined time interval.

An object of the invention is to render the control of the clothes drying operation fully automatic after the following specification taken in conjunction with the accompanying drawings wherein:

Fig. 1 is a longitudinal sectional view of a control device embodying this invention;

Fig. 2 is a sectional view taken along lines II-II of Fig. 1;

Fig. 3 is a sectional view taken along lines IIIIH of Fig. 1;

Fig. 4 is a schematic view of the electrical apparatus and the control device therefor; and

Fig. 5 is an enlarged perspective view of a detail.

Referring more particularly to the drawings, the control device is shown as comprising a cup-shaped casing 10 of insulating material provided with a cover 12 for the open end thereof, carrying a centrally disposed cupshaped housing 14. In one end thereof the casing 10 has mounted a pair of fixed contacts 16, 18 and a pair of connector terminals 20, 22 carried thereby for conmotion to a suitable source of electric current L1, L2 in series with a heating element 21 of a conventional clothes dryer.

Similarly, a pair of fixed contacts 24, 26, carrying terminal connectors 28, 30 are mounted in the other end of the casing 10 for connection to the same source of electric current L1, L2 and in series with a drum motor 29 in the clothes dryer.

A control lever 32 formed of insulating material of generally rectangular configuration is disposed within the casing 10 and is provided with a first contact bridge element 34 for cooperation with the fixed contacts 16, 18 and a second contact bridge element 36 for cooperation with the fixed contacts 24, 26.

As shown in Figs. 2 and 3, the lever 32 is riveted or otherwise secured at 38 on a flexure plate 40 which is releasably mounted on the sides of the casing 10. A pair of pins 42 secured to the casing are received in elongated slots 44 formed on both ends of the plate 40. It will be apparent that in this manner, the lever 32 is adapted for limited pivotal movement about the axis XX through the longitudinal axis of the flexure plate 40 but is prevented from pivotal movement about the axis Y-Y. The slots 44 and pins 42 also provide means for permitting limited reciprocal movement of the lever 32 from the position shown in Fig. 1.

Means for moving the lever 32 and the contact bridges 34 and 36 relative to the contacts 16, 18 and 24, 26, respectively is provided and is here shown as including a movable element operatively engageable with the lever 32. The movable element comprises a shaft 46 which projects transversely through the casing 10 and the cover 12 with one end thereof terminating adjacent the lever 32.

The lever 32 has a central bore 48 for slidably receiving a sleeve 50 therein and to be movable therewith. The shaft 46 is slidably and rotatably received in the sleeve 50 and abuts an adjusting screw 52 threadedly received in one end of the sleeve 50 to limit the downward movement of the shaft 46 relative to the lever 32 and to serve as a pivotfor slight angular movements of the lever 32. As shown in Fig. 1, the sleeve 50 is formed with an enlarged head defining a shoulder 54 adjacent the screw 52 and serves to limit the downward movement of the lever 32 relative to the shaft 46. A pair of relatively stiiT leaf springs 56, 58 joined at their ends 60, are connected at their midpoints to the lever 32 and a flared portion 62 of the sleeve 50, respectively. It will be apparent that the springs 56, 58 bias the lever 32 upon the shoulder 54 with the result that the sleeve 50 may move axially with respect to the lever 32 but the relative angular relationship between the lever 32 and the sleeve 50 will remain the same.

As previously stated, the shaft 46 is slidably and rotatably received within the sleeve 50 and for purposes of this invention, the internal diameter of the sleeve 50 is made slightly larger than the diameter of the shaft 46 for permitting limited angular movement of the shaft 46 with respect to the sleeve 50 and consequently with the lever 32, for a purpose which will presently appear.

Adjacent the contact bridge 34, the lever 32 is bored at 64 for slidably receiving a sleeve 66 having flared ends 68, 70. A coil spring 72 is interposed between the underside of the lever 32 and the flared end for biasing lever 32 against the other flared end 68.

The end 70 of the sleeve 66 is loosely received in a recess 73 formed in one wall of the casing 10 to limit the downward movement of the sleeve 66. A retaining pin 74 is mounted in a side wall 76 of the casing 10 and extends inwardly to a juxtaposed position with respect to the left end of the lever 32, as viewed in Fig. 1, ad-

jacent the contact bridge 34. The pin 74-is adapted to contact'a-nd limitthe upwardmovernent of that end of the v lever 32 aswill be described-more fully hereinafter.

In operation, actuation of the shaft 46 downwardly carries the lever 32 therewith against the bias of the spring 72 until the bridge 34 engages the contacts 16 and 13 and the bridge 36 engages the contacts 24 and 26. Further downward movement of the shaft 46 will move the shoulder 54 beyond the lever 32 against the bias of the springsz56, 58. It will-beapparent that the springs:56,:-5.8 serve asgan override mechanism for movement of the shaft 46 and as a relatively strong force for insuring ade'quate pressure between the bridge 3.4 and the. contacts 516, .18 and the bridge 36 and the contacts.24,"26 when the lever 32 is in a lowered position.

;Movement. of the shaft 46 and the sleeve. 50in an upwardlydirectiongpermits; the shoulder 54 to engage the under surface of the lever 32 allowingthe springs 56, 58 -to ,unflex to their normal conditionwhereupon the lever :32-will pivot about a fulcrum formed by the contacting ends of the shaft 46 and the screw 52, under action. of the spring 72 to disengage the bridge 34 from the contacts 16, 18.

.Upon'this occurrence, further movement of the shaft :46 will carry the lever '32 upwardly; however, because of the bias of the spring 72, the lever 32.will rotate slightly about the fulcrumrformedby the endof the shaft 46 and the screw 52 resulting in disengagement of the bridge -34.from the contacts 16,18 while maintaining the engagement of the bridge 36 with the contacts 24, 26. As the end of thelever 32, adjacent the bridge 34, approaches the pin74, the control mechanism for'actuating the shaft 46, as will presently appear, is designed to permit. a sudden axial movement of the same when the end of thelever 32 is slightly below the pin 74. A sudden movement of the shaft 46 will cause the instantaneous engagement of that end of the lever 32- with the pin 74, pivoting of the lever about the pin 74 and the upward movement of the other end of the lever 32 adjacent the bridge 36 resulting in a snap-action disengagement of the bridge 36 from the contacts 24, 26.

.Means for moving the shaft 46 manually to effect closing of the contacts 16, 18 and 24, 26 and for automatically opening the same at predetermined timed cycles will now be described.

The end of the shaft 46, remote from the lever 32 extends through a partition 80 of the casing 10 and projects into a chamber 82 of the cover 12. This end of the shaft 46 is formed with an enlarged portion 84 which is suitably slotted or otherwise formed to receive a manually operable knob 86 for rotation therewith. Suitable indicia (not shown) indicating units of time are imprinted on the knob 86 for registry with a reference mark (not shown) on the cover 12 for a pnrpose'which .will more fully appear hereinafter.

Secured to the medial portion of the shaft 46 within the chamber 82 is a plate 88 which carries a pair of oppositely disposed abutment means or followers which take the form of projections 90, 92 extending from the plate 88 and disposed parallel to the axis of the shaft .46. jThe follower 90 is positioned slightly farther from the axis of the shaft 46 than is the follower 92 for a purpose which will more fully appear hereinafter.

A relatively stationary detent member is engageable with'the projections 90, 92 for permitting axial movement of the shaft 46 and comprises a generally annular cam assembly 94 disposed within the housing 14. The cam assembly 94 includes a radial flange 96 which is adapted to be received in a suitable recess 98 formed in the housing 14 and secured thereto by a pair of screws 100 carried by the housing 14.

As shown in Fig. 5, an annular body portion of the cam assembly 94 extends axially from the flange 96 with the end portion thereof being adapted to define'a first pair of, axially-spaced helical surfaces 102, 104 having equal .helix angles for cooperation with the follower 90. C0-

axial with and positioned radially inward of the helical surfaces 102, 104 isa second pair of axially-spaced helical surfaces 106, 108 having equal helix angles for cooperation with the follower 92.

The lead of the helical surfaces 102, 104 is the same as the lead of the helical surfaces 106, 108. However, since the helical surfaces 102, 104 are disposed radially outward of the helical surfaces 106, 108, it will be apparent that the helix angle of the former will be smaller than the helix angle of the latter.

Annular extensions of the surfaces 102 through 108 may be of any suitable values depending upon the particular timing cycle and the timer mechanism used as will become apparent hereinafter. For purposes of illustration only and without limiting the scope of'the present invention, the cam surfaces 102 and 106 extend through approximately320 ..while the surfaces 10.4, 108 extend through approximately 30" As shown in 'Fig. 5, the surfaces 102 and 104 are axially spaced, being separated by an axial dropoff or wall 110. Similarly, the axially-spaced surfaces 106, 108 are separated by a wall 112. Each of the surfaces 104 and 108 terminate in a recess 114 (only one of which is shown in Fig. 5) which are substantially diametrically opposed with respect to each other and are adaptedflto receive the followers 90, 92. A stop projection.116-se curedto andprojecting outwardly of the housing 14 cooperates with a groove 117 in the knob 86 for limiting the rotational movement of the follower 92 in one direction. It will be apparent from the above description that for any position to which the'follower is moved with respect to the surfaces 102, 104, the follower 92 will occupy a similar position with respect to the surfaces 106, 108 diametrically opposed to that of the follower 90.

The shaft 46 extends slidably and rotatably through the open centerof the annular camassembly 94 so that the axial movement of the shaft 46 in one direction is limited by the engagement of the followers 90, 92 with the cam assembly 94.

' The length of the shaft .46 is such that, when the followers 90, 92 are positioned within the recesses 114, the spring 72 will hold the lever 32 in the position shown in Fig. 1 wherein the contact bridges 34, 36 are disengaged from their respective contacts. However, when the shaft 46 is moved axially to move the followers 90, 92 out-of the recesses 114, the actuatorshaft 46 is moved against thebias of thesprings 56, 50and 72 to move the lever 32 in the various controlling positions as previously disclosed. If the shaft 84 is rotated after it has moved the lever 32 to its contact closing position, the followers 90, 92 will engage the helical surfaces 102, 104.

It will be apparent that the axial thrust exerted on the shaft 46 by the springs 56, 58, 72 by way of the lever 32 will be transmitted directly to the shaft 46 and to the followers 90, 92 carried thereby. Since the helical surfaces 102, 104, 106, 108, are disposed at an angle to the line of action of this force, a-portion of the forcewill be'transformed totorque and will tend to rotate the shaft 46 with accompanying slidable movementof-the followers 90, 92 down the surfaces 102, 104,106,108. However, the helical surfaces 102 through 108 will exert a reactive force on the followers 90, 92, a portion of which will comprise a torsional componentacting in a direction to resist such slidable action of the followers It is an important feature of this invention that the coacting surfaces of the followers 90, 92 and the relatively stat1onary cam assembly 94 be so arranged that the operactuating shaft 46 from the stationary or detent assembly 94.

As previously stated, the helix angle of the surface 102 is smaller than the helix angle of the surface 106. It is desirable that the resistive force produced by the frictional engagement of the follower 90 upon the surface 102 be slightly greater than the force which tends to move the follower 92 along the helical surface 102. Accordingly, the helical surface 106 is formed with a relatively small helix angle selected to produce the desired resistance to slidable movement.

In order to balance these tendencies, the helix angle of the surface 106 is made slightly larger so that the force tending to produce slidable movement between the follower 92 and the surface 106 is slightly greater than the resistive force tending to inhibit this slidable movement.

From the foregoing, it will be apparent that the total torque acting on the shaft 46 as a result of the axial load thereon will be determined by the summation of the tendency toward slidable movement produced by engagement of the follower 92 with the helical surface 106 and the tendency to resist slidable movement produced by the engagement of the follower 90 with the helical surface 102. In a preferred embodiment of the invention, the helix angles of the surfaces 102, 106 are selected to produce a balanced condition with the moment exerted on the shaft 46 by the follower 90 being substantially balanced by the moment exerted on the shaft 46 by the follower 92. Thus, rotation and axial movement of the shaft 46 may be effected by the application thereto of a relatively small torque without regard to the magnitude of the axial thrust on the shaft 46 by the biasing effect from the spring 72.

Means is provided for applying a control force to the shaft 46 to efiect release of the plate 88 from the detent member 94. This means takes the form of an escapement controlled clock movement generally indicated by the reference numeral 120. The movement 120 is disposed within the chamber 82 and is secured to the housing 12 by any suitable means. The movement 120 may be of any conventional type and is shown here as including a driven gear 122 which meshes with a pinion 124 and being adapted to receive the shaft 46 so that the same may move axially relative to the pinion 124 while a torque transmitting relation is maintained therebetween. This connection is here shown as comprising a first leaf spring 126 secured at its medial portion to the pinion 124 and a second leaf spring 128 secured at its medial portion to the plate 88 which is secured to the shaft 46. The juxtaposed ends of the leaf springs 126, 128 are connected to- I gether at 130 so that rotational movement will be transmitted between the pinion 124 and the shaft 46 but, upon axial movement of the shaft 46, the springs 126, 128 will flex, causing no axial displacement of the pinion 124.

Operation In the non-operative position of the device, the controlled parts are positioned as shown in Fig. 1. To place the control device in operative position, the actuator shaft 46 is moved axially against the bias of the springs 56, 58 and 72 by manual manipulation of the knob 86 to the position wherein the followers 90, 92 are moved out of the recesses 114 beyond the outer extremities of the helical surfaces 102 through 108. Such movement of the shaft 84 will impart axial movement to the actuator shaft 46 moving the same against the bias of the spring 72 and positioning the lever in its lowest positon, to efiect engagement of the bridge 34 with the contacts 16, 18 and the bridge 36 with the contacts 24, 26. Further downward movement of the shaft 46 moves the sleeve 50 against the bias of the springs 56, 58 until the ends of the followers 90, 92 extend beyond the surfaces 102, 106.

The knob 86 is then rotated in a clockwise direction, to a desired time setting. Rotational movement of the knob before pointed out, the helix angles of the helical surfaces 102, 106 are such that the tendency towards rotational movement of the shaft 46 is balanced by the fric-' tional force resisting such movement. The shaft 46 will, therefore, remain in the position in which it has been set unless an additional torque is applied thereto to start rotation of the same and move the followers 90, 92 down the helical surfaces 102, 106.

The rotational setting movement of the knob 86 also rotates the pinion 124 which drives the gear 122 and winds the mainspring (not shown) of the clock movement 120. When the knob 86 is released, the torque of the mainspring is transmitted directly to the gear 122 and the pinion 124, the escapement mechanism (not shown) of the timer movement controlling the speed of rotation of the pinion 124, the plate 88, the shaft 46 and the knob 86 to their initial angular positions.

After a predetermined time interval, depending upon the angular extension of the surfaces 102, 106, the speed of the timer movement 120, and the position to which the followers 90, 92 have been placed with respect to the walls 110, 112 by rotattion of the knob 86, the mainspring (not shown) will rotate the shaft 46 and the plate- 88 and move the followers 90, 92 down the inclined surfaces 102, 106 until the followers 90, 92 are aligned with 106 and, since the followers 90, 92 are then in alignment with the walls 110, 112, the shaft 46 will be moved rapidly upwardly, as viewed in Fig. 1, until the followers" 90, 92 engage the helical surfaces 104, 108 adjacent the walls 110, 112. This portion of the axial movement of the shaft 46 is caused by the expansion of the springs 56, 58 until the shoulder 54 engages the lever 32 and for purposesof this invention, the engagement is made to occur at the instant the followers 90, 92 drop upon the surfaces 104, 108. Simultaneously with the dropping of the followers 90, 92 upon the surfaces 104, 108, and the engagement of the shoulder 54 upon the lever 32, the end of the shaft 46 adjacent the screw 52 becomes a fulcrum for the clockwise rotation of the lever 32 as viewed in Fig. 1, under the bias of the spring 72. Rotation of the lever 32 disengages the contact bridge 34 from the con- v tacts 16, 18 to open the circuit to the heater element 21. However, the left end of the lever 32, as viewed in Fig. 1, does not engage the pin 74, and the spring '72 holds the contact bridge 36 in engagement with the contacts 24, 26 thus maintaining a closed circuit for the drum motor 29.

Continued rotation of the shaft 46 and the plate 88 under the torque of the mainspring (not shown) of the timer movement 120 moves the followers 90, 92 along the surfaces 104, 108. After a predetermined time interval set by the angular extension of the surfaces 104, 108 and the speed of the timer movement 120, the followers 90, 92 will occupy a position in alignment with the recesses 114. In this position of the followers 90, 92, the spring 72 will have moved the left end of the lever 32 in a position almost contacting the pin 74. Since the followers 90, 92 are in alignment with the recesses 114, the shaft 46 will be moved rapidly upwardly under the bias of the spring 72. Simultaneously with the axial movement of the shaft 46, the left end of the lever 32 contacts the pin 74 which becomes the fulcrum for the lever 32 and the spring 72 rotates the lever 32 in a counterclockwise direction with a snap action to disengage the contact bridge 36 from the contacts 24, 26 to open the circuit to the drum motor 29.

When the followers 90, 92 move into the recesses 114, further rotation of the shaft 46 is prevented. The clock movement 120 will then stall and further unwinding of the mainspring is prevented. Thus, the mainspring will never be permitted to run down and a substantial torquemay be exerted thereby on the shaft 46 in all angular positions of the shaft 46 to eliminate any danger of in: suflicient winding of the mainspring when the timeris set to operate at a small time interval. It is to be noted that since the followers 90, 92 are diametrically opposed to each other, they will engage and disengage the helical surfaces 102 through 108 simultaneously thereby preventing possible tilting and binding of the shaft 46.

It will be apparent from the foregoing that the illustrated embodiment provides a new and improved control device which permits sequential timed actuation of a plurality of control switches for controlling the energization of an electric heater and drum motor. The improved control device provides means for adjusting the time period for closure of the heater and motor circuits together, and, after the heater circuit has opened, to provide a fixed time delay until the motor circuit is open.

It will also be obvious to those skilled in the art that the disclosed or illustrated embodiment may be variously changed and modified, or features thereof, singly or collectively embodying other combinations than those illustrated without departing from the scope of the invention or sacrificing all of the advantages thereof, and accordingly the disclosure herein is illustrative only and the invention is not limited thereto.

1 claim:

1. In a control device, the combination comprising means defining a first pair of axially spaced helical cam surfaces, means defining a second pair of axially spaced helical cam surfaces concentric with said first pair, means forming an axially extending recess for each pair of axially spaced helical cam surfaces, a member including abutment means frictionally engageable with said sur-' faces and adapted to be received in said relieved portions, said surfaces and said member being axially movable and rotatable relative to each other, said pairs of helical surfaces being inclined at different predetermined angles, respectively, to render the frictional engagement of said abutment means therewith effective to produce a resistive force tending to prevent said slidable movement and an equal force tending to produce said slidable movement whereby a small rotative force will produce slidable movement, means for imparting axial and rotational movement to said member to separate said abutment means from said relieved portion and place the former in engagement with one helical cam surface of each of said pairs of helical cam surfaces, and actuating means for rotating said member to impart slidable movement to said abutment means relative to said one helical cam surface of each of said pairs of helical cam surfaces to move said abutment means into engagement with the other surface of each of said pairs of helical cam surfaces, said actuating means further rotating said member to impart slidable movement to said abutment means relative to said other helical cam surface of each of said pairs of axially spaced helical cam surfaces to move said'abutment means into registry with said relieved portions.

2. In a control device, the combination comprising control means movable between a plurality of positions and biased to one of said positions, a shaft operatively connected to said control means and axially movable to move said control means against said bias to another of said positions, means defining a first pair of axially spaced helical cam surfaces coaxial with said shaft, means defining a second pair of axially spaced helical cam surfaces concentric with said first pair, each pair of axially spaced helical cam surfaces being provided with an axially extending recess, a pair of followers movable with said shaft and extending axially thereof, said followers being constructed and arranged to be received in said recesses for locating said shaft in a first axial position wherein said control means is in said one position, a handle secured to said shaft for imparting axial movement thereto to move said followers out of said recesses and position said control means in another of said positions, said handle being operable for imparting rotational movement to said shaft and position ing said followers in engagement with one helical cam surface of each of said pairs of helical cam surfaces to hold said control means in said another position, one pair of helical surfaces being formed with a helix angle tending to produce relative rotation between said shaft and said surfaces under said bias when said followers are in engagement with said pairs of helical surfaces, the other pair of helical surfaces being formed with a helix angle tending to inhibit relative rotation between said shaft and said surfaces under said bias when said followers are in engagement with said surfaces and substantially balance forces tending to produce said relative rotation, and actuating means for rotating said shaft for imparting slidable movement to said followers relative to said one surface of each of said pairs of helical cam surfaces to move said followers into engagement with the other surface of each of said pairs of helical cam surfaces thereby moving said control means to still another of said plurality of positions, said actuating means further rotating said shaft for imparting slidable movement to said followers relative to said other helical cam surface of each of said pairs of helical cam surfaces to move said followers into registry with said recesses and return said control means to said one position.

3. In a control device, the combination comprising switch means including a first and a second stationary contact, lever means having a contact disposed on each end thereof for engagement with said first and second stationary contacts, respectively, a shaft operatively connected to the medial portion of said lever means, means defining a first pair of axially spaced helical cam surfaces separated by a drop-off and extending coaxial with said shaft, means defining a second pair of axially spaced helical cam surfaces separated by a drop-off and extending concentric with said first pair, each pair of axially spaced helical cam surfaces being provided with an axially extending recess, a pair of followers movable with said shaft and extending axially thereof, said followers being constructed and arranged to be received in said recesses for locating said shaft in a first axial position wherein all said contacts are disengaged, abutment means disposed adjacent one end of said lever means, resilient means normally urging said one end of said lever means into engagement with said abutment means, a handle secured to said shaft for imparting axial movement thereto against the bias of said resilient means to move said followers out of said recesses and position said pairs of contacts in engagement, said handle being operable for imparting rotational movement to said shaft and positioning said followers in engagement with one helical cam surface of each of said pairs of helical cam surfaces to hold said pairs of contacts in engagement, one pair of helical surfaces being formed with a'helix angle tending to produce relative rotation between said shaft and said surfaces when said followers are in engagement with said pairs of helical surfaces, being formed with a helix angle tending to inhibit relative rotation between said shaft and said surfaces when said followers are in engagement with said surfaces to substantially balance forces tending to produce said relative rotation, actuating means for rotating said shaft to impart slidable movem ent to said followers relative to said one surface of each of said helical cam surfaces to move said followers into engagement with the other surface of each of said pairs of helical cam surfaces whereby said resilient means disengages one pair of contacts and urges said one end of said lever means against said abutment means, said actuating means further rotating said shaft to impart slidable movement to said followers relative to said other surface of each of said pairs of helical cam surfaces to move said followers into registry with said recesses whereupon said lever means pivots about said abutment means to disengage the other pair of contacts. 7

(References on'following page) References Cited in the file of this patent UNITED STATES PATENTS Ferguson Sept. 26, 1911 Schenk Nov. 2, 1926 Porter May 24, 1932 Greis Aug. 15, 1933 Andersen May 7, 1940 Stattner Aug. 29, 1944 10 Clark Apr. 20, 1948 Schott Nov. 30, 1948 Van Sickle Jan. 4, 1949 Staley Aug. 1, 1950 Kaefer et a1. Mar. 20, 1951 Harris Mar. 26, 1957 Liebermann Oct. 1, 1957 Demi et a1. Oct. 22, 1957

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