US 2885686 A
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Description (OCR text may contain errors)
y 1959 I c. v. GIAIMQ 2,885,686
PROSTHETIC DEVICES Filed March 25, 1954 3 Sheets-Sheet 1 INVENTOR CAM/e455 K'M/Mfl A'ITORNEY May 12, 1959 CL V-(ELAHflC) PROSTHETIC DEVICES Filed March 25, 1954 TJE TEL s Sheets-Shet 2 53 43 ygf/ f6 ATTORNEY May 12, 1959 c. v. GIAIMO PROSTHETIC DEVICES 3 Sheets-Sheet 3 Filed March 23, 1954 INVENTOR CHI/e155 1/6/4440 a? u, m?- N ATTORNEY United States PROSTHETIC DEVICES Charles V. Giaimo, South Orange, N.J., assignor to The Lionel Corporation, New York, N.Y., a corporation of New York Application March 23; 1954, Serial No. 418,033
11 Claims. (Cl. 3--1.1)
This invention relates to prosthetic devices and more specifically to a new and improved artificial aid for the human hand to assist in or wholly undertake digital manipulations in cases where the muscles or nervous system have been damaged or injured in such a manner as to prevent normal functioning of the digits, also to effect normal operations where one or more digits have been lost.
The design and construction of artificial aids for such purposes has presented rather substantial difiiculties in that a practical and useful device must be simple, light in weight, convenient and comfortable to wear and yet must supply forces comparable to those muscularly de veloped by the hand. Moreover, readily accessible and operable means must be provided for the control of the apparatus inaccordance with the desires of the user. This invention overcomes these difliculties and provides effective and practical means that can be readily attached to the hand and removed therefrom.
Another object of the invention is an improved hand appliance for the movement of one or more fingers rela tive to the thumb to enable the user to perform many tasks normally performed by the hand. This is attained by a simplified, light weight structure coordinated with the users hand to give utmost comfort to the user and yet perform the desired tasks with the requisite amount of power. Rather than use forces developed by the users muscles held tense for considerable periods of time at the expenditure of muscular and nervous energy, the present invention relies upon electromechanical devices to operate the mechanism and hold it in selected positions so that the user can be relaxed at all times.
Still another object of the invention is an improved breath actuated control for prosthetic devices in accordance with the invention operable in response to lung produced air pressure. In this way the user may readily control the operation of one or more units as may be desired, even though the paralysis may be of such a nature as to prevent control by other body parts.
Still another object of the invention is an improved electro mechanical apparatus for operating the hand appliance wherein the power applied to the hand appliance can be accurately controlled and regulated in accordance with the requirements of the user and avoid damage either to the aid or to the user.
Another object of the invention is an improved power operated hand appliance that is particularly adapted to securely hold small tools such as pens, pencils, toothbrushes and the like, and at the same time enable the holder to grip paper, and perform other similar actions.
The above and other objects and advantages of the invention will become more apparent as the description proceeds.
The accompanying drawings show, for purposes of illustrating the present invention, one embodiment in which the invention takes form, it being understood that the drawings are illustrative of the invention rather than limiting the same.
In the accompanying drawings:
Figure 1 is a perspective view of an embodiment of the invention adapted for breath control and showing it in use;
Figure 2 is another embodiment of the invention along the lines of Figure 1 illustrating alternative control means;
Figures 3 and 4 are top and bottom views respectively of a hand appliance in accordance with the invention;
Figure 5 is a side elevational view of the apparatus shown in Figures 3 and 4;
Figure 6 is a back elevational view of the apparatus of Figure 5;
Figures 7 and 8 are top and side views of a modification of the embodiment of Figure 5;
Figure 9 is a cross sectional view of Figure 4 taken along the line 9-9 thereof; 3
Figures 10, 11 and 12 are crosssectional viewsofFigure 5 taken along the lines Ill-10, 11-11 and 12--1-2 thereof.
Figure 13 is a cross sectional view of a breath operable control device in accordance with the invention;
Figure 14 is a cross sectional view of Figure 13 taken along the line 14-14 thereof;
Figure 15 is a top view in partial section of the power drive for the prosthetic device shown in Figures 1 to 6;
Figure 16 is a cross sectional view of Figure 15 taken along the line 1616 thereof;
Figure 17 is a' cross sectional View of Figure 16 taken along the line 17-17 thereof;
Figures 18 and 18a are fragmentary sections on the line Iii-18 of Figure 15 showing the spool and friction clutch at enlarged scales; and
Figure 19 is a wiring diagram.
The essential elements of one embodiment of the invention are illustrated in Figure 1 in the manner in which it would be employed by a user with an impaired hand. It comprises three separate elements designated generally as the hand engaging apparatus 10 with fixed and movable parts to be described, the power drive 11 and the control device 12. The control device includes means operable by air pressure and connected by a cable 13 to the drive mechanism 11. It is supported in operative position by a breast plate 14 and a strap 15 encircling the neck of the user. The power device 11 has provision for the independent operation of two mechanisms such as hand engaging devices 10, or if desired, independent operation of two fingers on a single device. For clarity, only one power drive 11 is shown coupled to one hand engaging apparatus '10 by cables or sheathes 16 and 16a connected to the fixed parts of apparatus 10 and tension wires 17 and 17a which operate in response to the power drive to move the index finger of a paralyzed hand toward and away from the thumb which is positioned relative to the body or metacarpal portion of the hand. Thus the index finger is moved either in one direction or the other merely by applying air pressure to the mouthpiece 18 of the control 12. For illustration, the user of the apparatus is shown holding a pen or pencil 19, which has been re moved from a holder 20.
Figure 2 illustrates an alternative control device which is denoted by the numeral 21 and may be operated by engaging it between the arm and the body or by foot action or the like. Thus the power drive can be operated by any type of control means best suited for the particular individual.
Hand engaging apparatus The hand engaging apparatus is shown in Figures 3 to 12 inclusive, and while it is preferably fabricated to fit the contour or shape of the hand of the particular user, it has been designed and arranged in such a manner that a limited number "of designs will meet the re- 3 quirements of a large number of individuals and thus avoid the expense of specially fabricating the appliance for each individual.
More specifically, this prosthetic device has a U-shaped body part or metacarpal clamp 22 which engages the metacarpalportion of the hand. vOneleg 23 of the body part22 is shaped to overlie the back of the hand as shown in Figure 3, and then curves downwardly in back of the thumb to meet the thumb plate 24. This plate is an elongated member which extends generally in line with the normal position ofthe thumb 2S and is shaped to conform with the front or underside thereof as shown in Figure 5. The forward portion of the upper metacarpal plate 23 also curves downwardly at a posi- "tion forwardly of the thumb '25 and joins with a lower, palm fitting metacarpal plate 26 to form the other leg of the U-shaped member 22. The lower metacarpal plate, nesting in the palm of the hand, lies between the upper plate 23 and the thumb engaging plate 24 and with the upper plate snugly fitting the back of the hand. While the'members 23, 24 and 26 may be fabricated in any suitable manner, they are preferably molded or shaped from a single piece of material such as metal, plastic or the like. From Figures 4 and 5, it will be observed that these three members thus form a rigid or relatively rigid structure adapted to clamp the hand and receive the thumb.
The thumb is held firmly against the thumb plate 24 by a pair of thumb straps 28 and 29. These straps may be formed integrally with the plate 24 or secured thereto in any desirable manner and positioned relative to the thumb to hold it firmly against the plate 24. For this purpose the strap 28 preferably engages the joint in the thumb between the first and second phalanges to prevent it from moving outwardly while the strap 29 encloses the end of the second phalanx of the thumb and about the nail thereof. 'The strap 29 forms a depressed area or socket for the reception of a pen, pencil or other instrument as shown in Figures 1,5 and 11. It is preferably provided with rubber tips indicated at 30a and 30b. This depressed portion cooperates with additional instrument engaging means as will be described to hold an instrument firmly against either lateral or longitudinal movement relative to the hand.
The apparatus thus far described functions to hold the metacarpal portion of the hand and the thumb rigid one relative to the other but movable under the action of the wrist. In order to elfect motion of the index finger relative to the thumb a series of three finger engaging members 31, 32 and 33 are hinged one to the body member 22 and to one another. The first member 31 is hinged to the body part 22 at 34 by rivets or other suitable means so that it may be moved in a plane substantially at right angles to the upper metacarpal plate 23 to coordinate with the normal movement of the index finger about the knuckle joint. This member may be 'formed from a single sheet of material and comprises a pair of side members 35 and 36 joined by a bottom bracket 37 and a narrow upper band 38. The side members 35 and 36 are provided with front pivot points 39, '39 spaced from pivot point 34 a distance roughly corresponding to the length of the first phalanx of the index or, forefinger. The upper strap 38 extends somewhat above the finger itself, as observed in Figure 5 and carries a small eye 41 through which passes the exposed end of the control wire 17 beyond the sheath or cable 16.
The pivots 39 cooperate to rotatably support the next member or link 32 surrounding the second phalanx of the forefinger. Link 32 is constructed similarly to link 31 and has a pair of side members 42 and 43 pivotably attached to the link 31 at 39, 39, a bottom member 44 which is tapered inwardly to form a narrowed central section having a length slightly less than the distance between the second and third nodes of the forefinger. 32 has an upper strap or band 45 centrally positioned Link and extending well above the finger in the same manner as the band 38 of link 31 and carrying a control wire engaging eye 46. The forward end of link 32 is provided with a pair of pivot points 47, 47 similar to the pivot points 39, 39 of link 31 and spaced therefrom a distance corresponding to the length of the second phalanx of the forefinger. These pivot points carry the third link 33 to complete the assembly.
This third link 33 differs from the links 31 and 32 in this embodiment of the invention in that it is elongated to extend beyond the end of the finger and in the actuated or closed position shown in solid lines in Figure 5 extends to apoint approximately in line with but spaced outwardly from the end of the thumb. As will be shown, this structure provides for a firmer and more positive grip on the instrument 19 to be held by the device. The link 33 is similar in construction to the links 31 and 32- in that it has a pair of side members 49 and 50, a curved bottom member 51 and an upper strap 53 extending well above the finger. This strap carries an eye 53' for the attachment of the end of the control cable 17 which functions under tension to straighten the position of the links one relative to the others.
The inner side of the link 33 is connected at 53" to the end of tension wire 17a which passes inside the portions 51, 44 and 37 of links 33, 32 and 31 respectively, so as to move outwardly between them and the finger when the links 31, 32 and 33 are shifted to extended position by pulling on wire 17.
The ends of the side members 49 and 50 of link 33 terminate in plate member 54 riveted or otherwise secured to the side members 49 and 50. If desired the end member 54 may include a block 55 as shown in Figures 7 and 9 held in place by a pair of screws 56 or other suitable means. This block and the end piece 54 are provided with a central threaded opening 57 to receive and hold special devices that may be desired for the particular work an individual may do. For instance, a rubber knob or end piece 58 may be attached by a screw 59 for actuating a typewriter key 59' such as that illustrated in Figure 8 of the drawings.
The sheathes 16, 16a for wires 17 and 17a are anchored to the body part 22 by means of a pair of posts 60 and 61 respectively. These posts may be welded or otherwise fastened to the plate 23 as shown in Figures 3 and 12. Each part has a transverse opening therein to receive a cable sheath and a longitudinally disposed set screw 62 to secure the sheath in place. The sheath 16 extends but a short distance past the post 60, leaving the unguarded wire 17 extending through the eyes 41 and 46 for attachment to the eye 53 on the link 33. The sheath 16a of Wire 17a extends beyond post 61 as shown in Figure 5, with the wire 17a extending through the links 31, 32 and 33 as above indicated. With this arrangement, as the wire 17a is placed under tension, it will cause the links to assume the curved position shown in solid lines in Figure 5, while tension on wire 17 will straighten the links as shown in the dotted position of Figure 5. It is to be observed that the links 31 to 33 normally very loosely engage the forefinger and the stress on the links when they engage an implement such as the pencil 19, is borne wholly by the links themselves. The mechanical parts operate just the same, even though the finger, or thumb or both are absent.
In order to limit the outermost position of the links 31 to 33 relative to each other, the adjoining ends of the links are provided with cooperating lugs or stops 65 to 68, inclusive, as shown in Figures 3 and 8. A stop 69 carried by the body part 22 is provided to limit the inward movement of the link 31.
The link 31 carries a Z-shaped tab or stop member 70 provided with rubber lining 70 which faces toward the thumb and as shown in the drawings, is spaced some distance away from the link 31, to provide space to receive a pencil or other implement. In use, the implement such assaese as the pencil 19 is held by forces applied to the top of the pencil by the end of the finger piece 33 and the bracket 70 and by opposing forces applied to the under surface of the pencil by the parts 29.
When the artificial hand is opened, a pencil or other implement supported as shown in Figure 1 may be picked up. The user first brings the end of the thumb piece against the near or under face of the tool or implement. Then he places the hand in position to have the tab 70 above the remote face and then force is applied by the wire 17a to close the finger piece from the dot-dash line position of Figure 5 to the full line position. Now pressure is applied against the pencil at two spaced points on the uppersurface and at an intermediate point of the lower surface. A similar procedure is followed where the user places the pencil in position manually.
Power drive The power device 11 for supplying motive power to the wires 17, 17a is shown in Figures to 18a and the wiring diagram in Figure 19. The power device 11 comprises a box 71 of wood or other suitable material having a central horizontal partition 72 to provide a lower compartment for housing the control mechanism for operating wires 17 and 17a. The transformer 73 includes a primary winding 74 for connection to a suitable supply of alternating current such as 110 V. cycles, a secondary winding 75 and a movable switch arm 76 for selecting the output voltage of 6 to 24 volts to be applied to the conductors 77 and 78. A suitable low voltage, two circuit transformer is shown in Patent No. 2,526,456. While a transformer is illustrated as the source of low voltage, it is quite apparent that a low voltage battery source may also be used, such as the battery of an automobile, boat or other similar vehicle. The voltage across leads 77 and 78 is applied to the motor 79 and reversing switch 80 through a control switch 81 in the control device 12. The reversing switch 80 is in the form of a drum 82 against which bear brush contacts which are interconnected with the motor armature 83 and field coil 84. Rotation of the drum, which is in effect a double pole double throw switch, acts to successively start the motor in one direction, stop the motor, start the motor in the other direction, then stop it. The drum advances step by step and rotates under control of the ratchet and pawl 85 which in turn is actuated by the plunger magnet 86 connected between the leads 78 and 77. The motor armature 83 is mechanically coupled with a gear reduction mechanism having a worm 87 and worm gear 88. The worm gear is in turn coupled with a spool and clutch assembly 89 shown in detail in Figures 18 and 18a. While the motor can drive such gears in either direction, they are irreversible, or self locking and cannot be driven by turning the spool and clutch assembly.
The relative positions of the motor 79, reversing switch 80 and spool and clutch assembly 89 are shown in Figures 15 and 16, the wiring having been omitted for clarity. The motor 79 together with the gear box 90, which houses the reduction gearing 88, 89 and in effect form a single unit, are supported by a spring member 91 which in turn is bolted to the upper side of the partition 72 by a pair of bolts 92. The output shaft 93 of the gear box 96 carries the spool and clutch assembly 89 which is aligned with an opening 94 in the top side of the box to expose a knob 95 for adjustment of the clutch; A second clutch and motor assembly is denoted by the numeral 89 (Figure 15) and is identical in every respect to the one now being described.
Referring now to Figures 18 and 18a, the pulley and clutch assembly 89 comprises a spool 96 having a hub 97 for the reception of an expansible slotted, tubular friction member 98. This friction member receives an expansible insert 99 adapted to be compressed lengthwise and expanded outwardly by the knob 95 threaded on 5 the shaft 93. The friction between spool 96 and friction member 98 is varied by adjustment of the knob.
The control wires 17 and 17a are preferably a single wire wrapped about the spool 96 several times or may constitute individual wires each anchored to the spool and wound about it several times with one wire being wound in one direction and the other in the other direction. The sheathes 16 and 16a which must absorb compressive stresses pass through openings 101 in the box '71 and are anchored to a cross member 102 carried by a bracket 103 which in turn is secured to the gear box 90. As the other ends of the sheathes are connected to the hand carried unit 10, the wires may be kept taut at all times.
Control of the output voltage of the transformer 73, which is connected to a suitable power source by the dual lead 104 is accomplished by the control knob 105 coupled with shaft 106 to which the switch arm 76 is secured.
- Control switch One embodimentof a control for the motor reversing switch is shown in Figures 13 and 14 and constitutes an air pressure switch generally denoted in Figure 1 by the numeral 12. The assembly is supported about the neck of the user by a breast plate 14 and an adjustable mount 108 which can be locked in a convenient position by means of the knob 109. The switch assembly which performs the function of switch 81 of Figure 19 shows a rectangular housing 110 secured to the mount 108 by a shaft 111. Extending upwardly from the housing 110 is a tube 112 having a mouth piece 113 on the upper end thereof. The mouth piece includes an inlet duct 114 communicating with a chamber 115. This chamber is in turn coupled by means of a passage 116 to the cham her 117 which communicates with the central passage 118 in the tube 112. The tube 112 is supported from said housing 110 by engagement with the top closure member 119 of a cylinder 120 .attached to bracket member 121. Within the cylinder is a cup-like piston 122 which is movable downwardly under. the action of a slight amount of air pressure applied to the mouth piece 113.
To the right of the cylinder 120, as viewed in Figure 13, is a micro, or other suitable switch 123, having a switch actuating arm 124 which extends outwardly and upwardly to engage the piston 122. The switch 123 is preferably of the single pole single throw type and the two leads thereof, denoted by numerals 125 and 126 extend through the bracket 121 and are connected to a female receptacle 127 mounted on the underside of housing 110. Connection is made to the switch by a pair of leads 128 and a male plug 129 adapted to engage the receptacle. The leads 128 are of course interconnected with the motor circuit to turn it on or otf in the manner described in connection with Figure 19. Thus, as air pressure is applied to the mouth piece 113, the switch 123 is actuated to its on position. Release of the pressure or momentary application of negative pressure as by sucking, will turn the switch off.
Operation In operation of this device, the user merely slips his hand into the prosthetic device 10 of Figure 1, supports the control device 12 about the neck and plugs the power unit 11 into a supply of electric energy. The device is now ready to operate. Assume that the forefinger is in the raised position and it is desired to lower it to grip a pencil or other elongated instrument 19. The user blows on the mouth piece 113 to turn the motor on. If the motor runsin the proper direction, the finger will move downwardly under the action of wire 17 with the sheath 16 resisting compressional stress produced by placing the control wire under tension. When the finger has moved to the lowermost position, the stress on the control wire will of course increase and the clutch in the spool will slip. The user can then stopblowing on the mouthpiece and the finger will stay locked in the lowered position because of the self locking action of the reduction gearing 90. I
Now, should the operator desire to release the grip, the next impulse on the control switch will start the motor in the reverse direction and apply tension to cable 17a.
The speed of operation of the unit can be adjusted by controlling the voltage on the motor 79 by means of knob 105 and control the friction in the pulley and clutch assembly by the adjusting knob 95. Should there be a power failure, the spool can be turned manually in either direction by grasping the wings 89a. The power unit 11 may be used to operate two devices for the right or left hands, and they may function simultaneously or independently as may be desired. Should it be desired to use an arm switch such as switch 21 in place of the air pressure switch 12, it is merely connected in place of the air operated switch and secured under the arm in such a manner that the user can operate it merely by moving his arm against his body. It is to be noted that in the case of. either switch, only momentary actuation is required to move the forefinger upward or downward, so that continuous air or arm pressure, as the case may be, is not required.
Since it is obvious that the invention may be embodied in other forms and constructions within the scope of the claims, I wish it to be understood that the particular form shown is but one of these forms, and various modifications and changes being possible, I do not otherwise limit myself in any way with respect thereto.
What is claimed is:
l. A prosthetic device for the hand comprising a body part adapted to engage the metacarpal portion of the hand, a plate secured to said body part for engaging and holding the thumb, a series of pivoted links connected one to the other and to said body part for engagement of and movement with at least one finger of the hand, an upper control wire slidably engaging the upper side of said links and secured to the distal link, and a lower control wire slidably engaging the under side of said links and also secured to the distal link, said upper and lower control wires being simultaneously operative, whereby the application of tension to the one wire will raise the links and the finger engaged thereby and the application of tension to the other wire will lower the links, wherein instrument engaging tabs are carried by the body part and one of said links and said thumb engaging plate is provided with a recessed portion to receive the under side of said instrument whereby the end of the distal link upon engaging the instrument at a point beyond the thumb cooperates with said tabs to secure the instrument firmly against said thumb.
2. A prosthetic device for the hand comprising a relatively rigid body part having a metalcarpal clamp and thumb engaging means, a plurality of finger engaging links hinged one to the other and to said body part and movable toward and away from said thumb engaging meansv and means for engaging and holding an instrument between said links and thumb engaging means including at least one instrument engaging tab adjoining the point of connection of said links and body part and instrument receiving means on the end of said thumb engaging means.
3. A prosthetic device for the hand comprising a metacarpal clamp, thumb engaging means secured to said clamp, a plurality of links hinged one to the others and to said clamp for engaging a finger, a pair of control members for said links each including a wire and surrounding sheath, said sheaths being secured to said clamp with one of said wires engaging the upper side of said links and the other wire the bottom side of said links whereby a force applied between the upper wire and its sheath will move the links in one direction and'a force applied between the other wire and its sheath will move the links in the other direction, and spool means coupled with said wires and sheaths for remotely controlling said links.
4. A prosthetic device for individual use comprising a U-shaped clamping member for engaging the metacarpal portion of the hand with the central portion of said clamping member lying between the thumb and index finger, thumb engaging and supporting means including a plate secured to said U-shaped member and extending in line with and along the underside of the thumb, means on said thumb engaging means for holding the thumb in position thereon, a series of at least three tubular-like links hinged one to the other and to said clamping member for loosely engaging and holding a finger, said links being arranged for movement toward and away from the thumb engaging and supporting means, a pair of control wire and sheath assemblies, means for securing the sheath of each assembly to said clamping member, means on the top side of the first and second links for slidably engaging one of said wires, means on the bottom side of said first and second links for slidably receiving the other of said wires, and means on the distal link for fixedly securing the ends of each wire whereby a tensile stress exerted between the upper wire and its sheath will move the links upwardly and between the lower wire and its sheath will move them downwardly.
5. A power unit for a prosthetic device having a pair of control wires for the operation thereof comprising a motor, control means for the motor, a reversing switch interconnected with said motor and responsive to said control means to start, stop and reverse the motor, gear reduction means mechanically coupled with said motor, and a spool including adjustable clutch means coupled with said gear reduction means whereby the ends of a wire wound about said spool will be alternately placed under tension and relaxed as the motor is rotated first in one direction and then the other.
6. A power unit according to claim 5 wherein said reversing switch includes a ratchet operating mechanism and a plunger magnet for operating said ratchet connected in parallel with said motor whereby the motor may be reversed by interruption of the energy applied thereto.
7. A power unit according to claim 5 wherein said motor and gear reduction unit function as a brake to prevent rotation of the pulley under the stress of said wire.
8. A control for a prosthetic device comprising a cylinder and piston assembly, a tube communicating with said cylinder, a mouthpiece on said tube having an opening therein communicating with the opening in said tube, and a switch including an actuating lever responsive to oscillatory motion of said piston whereby application of air pressure to said mouthpiece will move the switch lever in one direction and release of said air pressure will move the switch lever in the other direction.
9. A control according to claim 8 having a mount comprising abreast plate, a neck strap and means between said control and breast plate for adjusting the position of said mouthpiece.
10. A prosthetic device for individual use comprising gripping means having at least two relatively movable members, a pair of control wires operating under tension and connected with said gripping means, one wire for moving the members toward one another, the other for moving them away from one another, a power unit including a self-locking reduction gear assembly drivingly connected with said wires for applying tensile stress individually to said wires, reversing means in said power unit, and control means for operating said power unit in one direction to stress one wire and move said members into gripping position and in another direction to stress the other wire and move said members out of gripping position, said power unit including a spool for engaging said wires and an adjustable friction clutch for limiting the power transmitted by said unit to said wires.
11. A prosthetic device for individual use comprising 9 a gripping means having at least two relatively movable members, a pair of control wires operating under tension and connected with said gripping means, one wire for moving the members toward one another, the other for moving them away from one another, a power unit including a self-locking reduction gear assembly drivingly connected with said wires for applying tensile stress individually to said wires, reversing means in said power unit and control means for operating said power unit in one direction to stress one wire and move said members into gripping position and in another direction to stress the other wire and move said members out of gripping 10 position, said control means including an air operated piston coupled with said power unit.
References Cited in the file of this patent UNITED STATES PATENTS 984,179 Aydt Feb. 14, 1911 1,569,286 Laherty Jan. 12, 1926 2,526,456 Bonanno Oct. 17, 1950 2,535,489 Edwards Dec. 26, 1950 2,553,277 Robinson et a1. May 15, 1951