US2992502A - Handgun safety mechanism - Google Patents

Description

July 18, 1961 4. B. TwlGG HANDGUN SAFETY n/xEcHANIsM 3 Sheets-Sheet 1 Filed June 2, 1959 .inI

INVENTOR.

JERRY B. TWIGG ATTORNEYS July 18, 1961 J. B. TwlGG HANDGUN SAFETY MECHANISM 3 Sheets-Sheet 2 Filed June 2. 1959 IIII VIII VIII lNVENTOR.

JERRY B. TWlGf:`

July 18, 1961 J. B. TwIGG 2,992,502

HANDGUN SAFETY MECHANISM Filed June 2, 1959 3 sheets-sheet s lNvENToR 'TEAL JERRY B. `Twlsc;

ATToRNEY United States Patent O 2,992,502 HANDGUN SAFETY MECHANISM Jerry B. Twigg, Bethesda, Md. (R.F.D. 2, Ellicott City, Md.) lled .luue 2, 19'59, Ser. No. $17,615 11 Claims. (Cl. 42-66)` This invention relates to rearms ,and more particularly and specifically to a new and unique safety mechanism for, preventing accidental or improper discharge of handguns in the revolver class.

In recent years it has become an increasingly popular hobby to practice for and participate in so-called fastdraw piston shooting. This interest has developed in some 'locations into organized, controlled competition. Such competition involves the use of revolvers, usually the single-action type, which are drawn from a holstered position to a firing position Vand discharged with blank ammunition at a special electronic target, the entire sequence being performed agains-t time. However, the natural desire for accuracy as Well as speed with the revolver has remained with many inexperienced persons who are unaware of the hazards of using live ammunition in this manner and has resulted in many painful and crippling accidents. These accidents have not ben controllable through conventional revolver safety mechanisms because -the single-action revolver does not provide the manually operated safety common to the double-action revolver, which in itself requires a deliberate hesitation and physical effort to release the safety which is inconsistent with the objectives of so-called fast-draw shooting. For example, in the single-action revolver type of handgun a safety mechanism is employed which is brought into engagement automatically when the hammer is moved to the rst position of cock by thumb pressure on the hammer. This is provided merely to prevent the firing pin from resting on a loaded chamber. Subsequently, when the hammer is moved to intermediate and full cocked positions the safety is automatically disengaged and the gun thereafter is armed and capable of discharge.

ice

of the trigger at which time discharge of the revolver is made.

In addition to the foregoing description of a proper fast draw sequence it is important to note that the full sequence has been timed to .l2 second. lIt is because of this split second action and the fully armed condition of the revolver prior to the completion of its withdrawal from the holster that every contact between the hand` and the gun be positivev and in proper order. Itis usually the attempt of the novice to achieve the speed of the.

y draw, before mastering each step of the sequence, that be fully understood. In the practice of a fast` draw, the hand is moved from a position usually forward of and elevated above a bolstered revolver toa iinal position of p handgrip engagement 'with the but-t of the revolver to permit withdrawal of the gun from the holster and its subsequent elevation to apring position. In this, the most-,50;l

accepted sequence of hand andV arm movement, the hand moving downwardly and rearwardly to engagevthe gun first brings the thumb into contact with the hamrner of the revolver and begins the rearward cocking movement of the hammer. Simultaneously, the hand pivots on the thumb to bring the fingers of the hand in contact with the frontstrap of the handgrip and begins the withdrawal of the gun from the holster, the index finger, at this time, is laid along side the trigger guard. IWhen the hammer reaches its full cocked position at the end of its rearward movement the thumb continues in a rearward and downward direction off the spur of the hammer into place f on the stock or handgrip in opposition to the palm grip on the stock. The gun is securely gripped between the palm and the thumb following the upward removal of During this forward motion the index finger is brought Within the trigger guard to engage on the forward face results in the premature t discharge of the revolver.

Broken down into stages this occurs when the indexiinger enters the trigger guard and engages the `trigger prior. to the complete withdrawal of the revolver from the holster and allowing the thumb to slip from the hammer during intermediate stages ofvcocking or at full cock.

It is therefore a general object of the present invention to provide a safety mechanism which is designed to func--v tion during the fast drawn sequence to prevent accidental or premature discharge of the revolver prior to the time it reaches a proper ring position.

It is principal object ofthis invention to provide a safety mechanism for revolvers which acts automatically to disarm a revolver simultaneously with the cooking of the revolver hammer when the gun is in a verticalposition and to maintain said 'revolverin an unarmed condition until it reaches a horizontal iiring position at which time the safety will be automatically released,

Another object of this invention lies in the provision of a safety mechanism for revolvers which may be made a part of newly manufactured handguns without require-v. ment for modification of parts and components inthe forms and configurations now used, and a safety mechanism which may be readily and easily installed in existing revolve'rs without modification or alteration of any'parts A or components of these existing weapons.k 1'- It isa further object of this invention to provide a, safety mechanism for installation in revolvers,rwhich may be removably secured within the handgiip of a revolver and which may be renderedinoperative by thesimple removal of one component and itsstorage in a provided area within the `general structure of thesafety mechanis Still another object of this invention is they provision' f' of a 4safety mechanism for arevolver which is of ex-g`r gun.

removably secured within the handgrip of the revolver to function cooperatively with the mainv spring of the ,gun to` function as an 'automatic lock .and release safety, the function of which is determined and controlled entirelyV by the positioning and movement of the gun.

Still further objects and ladvantages of this invention will become readily apparent to those skilled in the art when Vthe following description is read in thel light of the accompanying drawings. v The nature of the present invention may be stated in'4 general terms as relating to a safety mechanism forl handguns of the'revolver class and includes a bracket side plate screw against the inside face of the backst'rapv thereof, an irregular bearing face on said bracket dis-,-l

posed toward the Ifrontstrap of the handgrip and opposed to and spaced Ifrom the main spr-ing of the revolver,

y'and a rolling bearing element freelyv disposed between Patentedv July 18, 1961 e tremely simple desi-gn and Vmanufacture andV which may* be readily and'simply installed in any revolver Vfor which;A so designed without modification or alteration of the'- lAnother object of this invention is the provision ofasafetyV mechanism for 'handgunsV of thereyolver class which consists of two components whichmy be readily,

to be secured within the handgrip of the revolver by the 3 the bearing face of the bracket and the main spring and movable between the vopposedsurfaces of these components.

Referring no-w to the accompanying drawings in which like numerals designate similar parts throughout the several views:

FIG. 1 is a vertical sect-ion through a revolver disposed in a vertical position :incorporating the inventive safety mechanism withthe revolver hammer resting in a tiredy position.

FIG. 2 is a fragmentary view similar to FIG. l illus- 4trating-a revolver in a verticalposition with the hammer in a safety position of cock.

FIG. 3 is a view similar to FIG. 2 with the gun in a vertical position andthehammer and components of the safety mechanism in an intermediate position of cock.

FIG. 4 is a view` similar toyFIG.' 3 illustrating a revolver in a vertical position with the hammer `and safety mechanism components in a full cock position.

FIG. 5 is a fragmentary vertical section of the revolver incorporating the inventive safety mechanism where the revolver is in an intermediate position of elevation with the hammer in full cock position and the components of the safety mechanism in safety position.

vFIG. 6 is a view simi-lar to FIG. 5 with the gun disposed in a fully elevated firing position and with the safety mechanism disengaged;

FIG. 7 is a fragmentary vertical section of a revolver in Ia vertical position with the safety mechanism locking the hammer `in the instance of a premature triggering.

FIG. 8 is a pictorial illustration of the Ibackstrap bracket of the safety mechanism.

FIG. 9 is a pictorial illustration of one form of the bearing component of the safety mechanism.

FIG. 10is a sectional |View illustrating a modified form of the safety mechanism as an integral part of the backstrap.

FIG. 11 is a sectional elevation of a modiiedform of the safety mechanism, and

FIG. l2 is a pictorial illustration of the main spring wedge element.

yIt is important in order to clearly understand the function of the structural components of the present inven.d tion to recognize that the safety mechanism herein disclosedV cooperates functionally 'with the usual main spring found in the handgrip of the rewolver. In such cooperative function the main spring becomes a component of the safety mechanism in addition to performing its conventional function within the revolver structure. It is also essential to recognize that the safety mechanism constituting fthe present invention does not function as an absolute and positive lock against trigger operation but does serve to produce a very substantial deterrent to main spring operationy while in an engaged position and prevents the complete fall of the hammer by imposing a block against the hammer.

In the drawings, the novel safety mechanism constituting the present invention is shown, by way of example, in application to a vsingle-action revolver generally designated at 10. The revolver '10 consists, conventionally, of a barrel 12, a revolving magazine cylinder 14, each chamber of which serves as the tiring chamber 16 when in the topmost position of rotation, a handgrip stock 18, a trigger 20, a hammer 22 carrying a tiring pin 24 aligned with the firing chamber 16 land a hammer engaging main spring 26 extending throughout the interior length of the handgrip 18 of the gun.

AIn the construction shown the handgrip 18 of the gun is formed, in the usual manner, by a frontstrap element 28 which includes a plate member 30 for attachment below the trigger mechanism of the revolver, providing integrallytherewith a trigger lguard 32, and the downwardly and rearwardly extending bar or rib forming the front wall` ofthe handgrip, of the revolver.

The backstrap of the handgrip 118 consists of a curvilinear, L-shaped bar or rib member 34 which extendsk from adjacent the hase end of the hammer 22 downwardly and rearwardly in spaced relationship to the frontstrap 28 of the handgrip and which is provided at its lower extremity with a forwardly extending bottom plate 66 the forwardmost end of which underlies and is secured to the bottom end ofthe frontstrap member 28. The sides of the handgrip intermediate the back and front straps are enclosed by panels or plates, not shown, which are secured in place by a countersunk screw member in one of said plates threadedly engaging in a tapped boss formed on the inner face of the opposite plate, all of which is conventional.

The hammer member 22 of the gunis conventional in providing -a lever pivoted as at 36 transversely of the revolver immediately forward of the handgrip portion and generally centrally of an enlarged cam section 38 of the hammer. The upper extremityof the hammer supports the tiring pin 24 in projection from the forward face thereof and is provided with a shaped and usually knurled thumb grip projection 40 from the upward rearward end thereof to facilitate easy cocking of the hammer by its depression downwardly and rearwardly about the pivot 36'.

VIn conventional manner the enlarged cam 38 of the hammer is provided on its forward face with a series of notches 42 which cooperate with the conventional Sear 414.1 on the upper end of the trigger to permit the trigger Sear to retain the hammer `in selected positions of engagement with said notches upon rotation of the hammer downwardly and rearwardly about the pivot 36.

The cam 38 of the hammer is provided with an enlarged notched area generally designated at 46 in its lower rear portion defining a rearward projection 48 above said notch which is bifurcated longitudinally of the revolver to mount `a roller element 50 therein which engages the main spring 26 of .the revolver and against which the forward extreme free end of the main spring is'upwardly biased.

The main spring 26 consists of an elongated member formed of flat or tapered spring steel which also tapers in width from Xa base end 52 which is secured against the inner base end of the front-strap 28 of the handgrip through the upper free end thereof which is biased upwardly against the roller element 501 on the hammer projection 48 `as above described. As is seen, the anchoring of the base end of the spring together with its engagement with the hammer projection retains the spring in an arcuate condition which generally follows the arcuate configuration of the handgrip 18 of the gun within which the spring is mounted and wherein it is retained in spaced relationship from both the front and back strap members.

As is best seen in FIGS. 8, 9 and l2 of the drawings, the safety mechanism constituting the present invention consists of a safety head 54 and Ia bearing element 56. The safety head 54 takes the form of a generally L-shaped bracket member the base leg 58 of which is relatively short Iand the upper leg 60 of which curves arcuately from its integral joindure with the base leg throughout its upper and forwardly projected extremity. The curvature of the upper leg 60 of the safety head coincides with the curvature of the bar or rib member 34 forming the backstrap of the handgrip and the angularity defined between the upper yand lower leg portions at their point of intersectionl coincides with the angul'arity defined by the rear bar and bottom plate components of the backstrap of the handgrip.

The safety head is provided transversely of the front face of the upper leg portion thereof with a bearing surface consisting of a series of arcuate depressions or undulations 62 beginning immediately adjacent the forwardly.

projected extremity thereof Iand extending downwardly Iand. rearwardly for a spaced distance therefrom. Intermediate the length of the inner face of the, upper leg ponton' the safety head is provideawith an enlargedforwardly projecting boss section 64 having a transverse circular passage 66 which is positioned so as' to coincide transversely of the handgrip with the conventional screw member interconnecting the side panels of the handgrip. A second enlarged boss area 68 is Yformed within the angle defined between the upper and lower leg portions ofthe handgrip, and this 'area is provided with a cylindrical socket 70 transversely thereof of a diameter slightly larger than the diameter of the cylindrical bearing element 56 which, as seen in FIG. 9, consists ofa tubular metallic component formed of a length slightlyless than the transverse dimensions of the leg portions of the safety head and which is polished to provide a good bearing surface about the circumference thereof. This bearing element` can be spherical with a diameter less than the transverse dimension of thesafety head.

The incorporation of the safety mechanism herein disclosed in a revolver as described involves the removal of one side plate or panel of the handgrip of the revolver and the insert-ion of the safety head member 54 within the handgrip with the rear face of the upper leg portion of the safety head being positioned in coincidence with the inner face of the bar or rib 34 forming the backstrap of the handgrip, and with the lower f-aoe` of the lower leg portion resting on the inner face of the bottom plate of the handgrip. The positioning of the safety head is such that when the handgrip panel is replaced the conventional retainug screw will pass through the passage 66 in the forwardly projecting box portion 64 of the head, thus securing the safety mechanism firmly in place. Before replacing `the panel, the tubular bearing member 56 is inserted transversely of thehandgrip intermediate the front face of the safety head and the rearwardly disposed face `of the flat main spring 26 of the revolver at a point therebetween immediately Iabove the forwardly projecting boss portion 64 of the head member. The diameter of the bearing member is such that it will be freely movable between the upper surface of the forwardly projecting boss portion 6'4 of the safety head and the ridge 72 defining 'the lowermost extremity of the lowermost arcuate undulation 62 in the forward face of the head member. Each of the adjacent depressions or undulations 62 is separated by and defined by similarly projecting ridge sections 72 throughout `the series of said depressions.

-When the hammer 22 -is in ya fired position as shown in'FIG. lof the drawings, the hammer projection 48 and associated spring roller element 50 are in their uppermost position which permits the upper free end of the main spring 26 to assume its uppermost position of deflection and to assume its closest position to the series of undulations in the forward face of the safety head. As seen in FIG. 1, this close positioning of the spring and the safety headis such `as will prevent the movement of the cylindrical bearing 56 upwardly beyond its engagement with the -n'dge 72 defining the lowermost undulation by reason of its simultaneous contact with the rear face of -the main spring.

As the hammer 22 is moved `to its first position of cock, as shown in FIG. 2 of the drawings, the roller element 52 on the hammer projection 48 depresses the free end of the main spring suiciently to increase the spacing between themain spring yand the safety head to an extent whereby the bearing 56 is permitted clearance to pass the ridge 72 at the lower end of the lowermost undulation 62, but is restricted against further advance by the spacing between the ridge 72 separating the lowermost undulation from the next thereabove and the rear face of the main spring. Subsequent cooking of the hammer through its progressive positions of cock as determined by hammer notches 42 engaging the trigger sear `44, as shown in FIGS. 3 and 4 of the drawings, progressively increases the depression of the free end of the main spr-ing and simultaneously increases the spacing between the spring and the safety head permitting the step by step advance of the bearing Recalling to mind that in a fast draw sequence theV revolver is maintained in a bolstered position throughout the cooking operation of the hammer, it will be seen thatv the vertical positioning of the revolver in the holster will cause the cylindrical bearing 56 to move, under gravitationalY force, downwardly to the forwardmost position shown in FIG. 4 of the drawings in engagement between the rear face of the main spring and the outermost, forwardmost arcuate undulation 62 on the inner face of the safety head. Recognizing that the upward bias of the free end of the main spring acting on the roller bearing 50 in the hammer projection 48 is the matin triggering force which moves the hammer forwardly, it is seen that the bearing 56 is positioned to block the upward movement of the free end of :the spring thereby reducing greatly the ring force essential to move the hammer 22.

As therevolver lis withdrawn from the holster in its cocked condition and moved upwardly and forwardly.

from the holster the bearing 56 willbe subjected to forces of gravity land inertia which will cause it to move rearwardly and downwardly of the handgrip between the safety lhead and the main spring, as seen in FIG. 5 of the drawings, until it has passed the lower rearmost undulation and entered the enlarged gravity area immediately above the enlarged boss section 64, as seen in FIG. 6. Once the bearing has started its rearward movement between the spring and safety head, the free end of the main spring again exerts an upward bias on the hammer projection 48 which ybias becomes sufficiently freed of any :restraint by the bearing 56 as it approaches its lowermost position to permit the spring `to snap the hammer about its pivot forwardly to a firing position.

In FIG. 7 there is shown a position of the safety mechanism components relative tothe hammer which illustrates aprernature firing of the revolver while the safety components are in operative position. It will be noted that the bearing 56 is interposed between the safety head and the main spring retaining the free end of the main spring out of engagement with the hammer projection 48. Further, and most importantly, it is noted that the tip end of the free end of the main spring is in abutment with the forwardmost shoulder dening the hammer depression 46 in substantially direct opposition to the rearward movement of the cam portion of the hammer immediately inV the discharge of the revolver upon premature or accir dental triggering of the revolver prior to the time thel reaches an elevated position and prior to the time the cylindrical bearing is induced by gravity and inertia to move downwardly and rearwardly in the handgrip to an inoperative position.

An important detail of the structure embodied in the safety mechanism is the utilization of a wedge component 74, FIG. 12, which is located between the forwardly dis,- posed face of the main spring and the rearwardly disposed wall of the frontstrap 28 where the main spring is secured to the frontstrap. This wedge, which may be easily adjusted in proportion by filing, performs the function of properly adjusting the tension on the main spring and the positioning of the upper free end of the main spring in relationship to the hammer so that the abutment between the free end of the main spring land the rearwardly disposed shoulder of the cam section 38 of the hammer, as shown in FIG. 7, may be obtained. This wedge is drilled centrally as at 76 to permit it to be positioned intermediate the spring and front strap and secured in place by the screw normally-interconnecting these two elements at their base ends. f

'i In FIG. l0 of the drawings there shown amodification ofthe present invention which embodies all ofthe inventive concepts hereinbefore disclosed. by the simple expedient of the formation on the innerV surface of the bar or ribk element forming the backstrap of the handgrip of an irregular bearing surface designed to conform as a unit to the combined formation `formed by the separate backstrap and safety head members hereinbefore disclosed. In this moditicationarcuate depressions 78are formed directly in the inner face of the backstrap member andA aforwardly projectingrib 80 separates the upper and. lower sections of the handgrip cavity to the rear of the main spring 26 to limit the downward and rearward movement of the bea-ring element 56 confined within the handgrip between the main spring and the safety head configuration of the backstrap.

In FIG. 11 of the drawings there is shown a. further modification ofr this invention which embodies a safety head 82 substantially identical in all respect to the safety head 60 disclosed in FIG. 8 and described above with the single exception being in a slightreduction in front' to rear thickness of the upper leg portion .84 of the moditied safety head 1and the provision on the rearwardly disposed face of that leg portion of raised transverse rib areasv 86 at spaced locations therealong. The provision.

ofthe raised rib areas permits the easy tiling away of one or more of the rearward faces of these rib areas to permit the fitting of the safety head member more readily in the handgrip of an existing revolver without necessitating` the tiling or surface reduction of the entire rearward face of fthe safety head which might otherwise be necessary to attain a perfect t.

. AnY addition feature of the safety mechanism hereinbeforedescribed is the provision in each of the forms shown of a circular pocket, such as 70` in FIG. 8 of the drawings, 88 in FIG. '10, and 90 in FIG. 1l, adjacent the angular joindure of the two leg portions of the Vsafety head of such a configuration and diameter as to permit the reception therein of the roller bearing 56 for the purpose of storing the bearing element in afixed, inoperative position when it is desired to render the automatic safety mechanism inactive and yet retain the immediate availability of its structure and function for use when desired. The structures hereinbefore disclosed embodying the inventive concepts of the present safety mechanism pro-V vide a rolling bearing element interposed between the safety head of the mechanism andthe usual main spring of the revolver which serves to create their safety and release safety action as a result of the combined upwardly and forwardly directed'movement of the. revolver from a vertical to a horizontal position. Further, the safety action of the rolling bearing element is continuousfbetween the sequence steps of arming and dischargin g; the` revolver.

Y It is;evident from an examination of the structure and functionV of the safety mechanism hereinbefore disclosed that the safety action of the mechanism is not al momentary deterrent to hammer -action at stages in revolver action preceding the time when the revolver reaches a normal firing position but the mechanism provides a continuing safety factor a-t any time when the revolver may be triggered prematurely which safety action is only released when the hammer of the revolver is recocked. Art-,the same time the rolling bearing element would seek a position providing a secondary safety which would prevent discharge ofthe -gun at all times should a malfunction of the gun occur, such as could result from a broken trigger sear or broken trigger scar notch on the hammer, upon the occasion of a premature firing of the gun.

Thus, it is seen that an automatic safety mechanism has'been provided which will operate to afford a most desirable and necessary function in revolvers used: in fast draw competition. The safety mechanismr consti- .8 tuting thisy invention is intended tov be used primarilyfor training purposes and for aifording a maximum factor of:v safety in the use of `revolvers, but, the inventive concepts are not intended to replace the care and attention whichmust be given at all times to the proper handling and use of firearms.

Accordingly, having fully disclosed. and described. the structure and function `of the inventive concepts herein embodied, and having evidenced the attainment of the objects and advantagesrhereinbefore set forth, what is desired to be claimed is: t

I claim:

l. In combination with a handgun having a handgrip and a main spring in said handgrip engaging the hammer mechanism of the gun, a safety mechanism including, a bracket mounted within the handgrip, an undulatory surface formed along said bracket in spaced opposition tothe main spring, and a freely movable roller element interposed between the undulatory surface and the spring.

2. Iny combination with a handgun having a handgrip, firing mechanism, and main spring in said handgrip engaging said-firing mechanism, a safety mechanism including, a bearing surface formed inv spaced opposition to said spring, said bearing surface having a series of undulations therealong, and a bearingV element freely inter.- posed between said surface and said spring and movable therebetween by gravity.

3. In combination with a handgun including a handgrip stock, tiring mechanism, an elongated at main spring extending through said stock, a safety mechanism comprising, an undulatory bearing surface formed within the stock in spaced' opposition to the main spring, and a roller bearing element freely interposed between the surface and the spring.

4. In combination with the main spring of a revolver, a bracket member in spacedopposition to said spring and having an undulatory bearing surface throughout a portion of one lface thereof, 'and a bearing element movable between and in contact with the undulaitory surface of said bracket and the spring.

5. In combination with the handgrip of Ia handgun having forwardly and rearwardly disposed walls comprising, a generally L-shaped bracket of a configuration conforming to that of the inner surface of the rearwardly disposed wall of the handgrip, Iand an undulatory bearing surface formedl along one'face of said bracket member by a series of undulations of progressively decreasing depth and width.

6. In-combination with a handgun having an elongated ilat main spring operably associated with a tiring hammer, a safety mechanism including, an undulatory bearing surface in longitudinal spaced relationship to a portion of the ylength of said main spring, and a bearingelement freely interposed between said surface andv said spring.

7. A combination as defined in claim 6 wherein, said bearing surface includes a` series of. arcuate undulations formed transversely thereof and progressively spacedl longitudinally therealong. v

8. In a revolver havinga handgrip stock and an elongated at main spring extending therethrough, a backstrap for .the handgrip stock of said revolver including a generally arcuate bar having an undulatory inner face in spaced opposition to. said main spring, and,k a Vbearing element freely positioned between said spring and said undulartory face.

9. A revolver structure Ias defined in claim 8 wherein said undulatory face is provided with transversely formed arcuate undulations progressively arrangedlongitudinally of said face.

10. In combination with a revolver having a hammer and an elongated main spring in free biased engagement with therhammer, a safety mechanism including, abearing surface in longitudinal spaced relationship to a por.-4

9 tion of the spring, a bearing element between said spring and bearing surface, and said bearing being freely rollable to wedge the spring into opposed `abutment with the |hammer.

11. In combina-tion with a handgun having a hollow 5 handgrrip, one wall of said hfandgrip being provided with an unduilatory surface, `an elongated spring in said handgrip with a portion in llongitudinal spaced relationship io he undulatory surface, iand Xa freely movable bearing element interposed between said spring and said undulatory 10 surface.

References Cited in the le of this patent UNITED STATES PATENTS Freund Oct. *17, 1876 Mann Dec. 15, 1908 Moore May 31, 1910 Kaldenberg Oct. 10, 1911 Donadio Aug. 12, 1919 Kneubuehl Feb. I17, 1942 FOREIGN PATENTS Germany Jiune 18, 1919

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