US2367379A - Self-locking threaded device - Google Patents

Description

Jan. 16, 1945. c, w SQLDAN I I SELE-LOCKINGTHREADED DEVICE Filed Oct. 25, 1944 5 Sheets-Sheet 1 Jan. 16, 1945.

C. W. SOLDAN CKING THREAiDED DEV SELF-LO Filed 001:. '25, 1944 s Sheets-Sheet s Jan. 1945. c w; SQLDAN 2,367,379

' SELF-LOCKING THREADED DEVICE Filed Oct. 25, 1944- g 5 Sheets-Sheet 4 76 (Inf/veg I z I Clqzpnce W'qlilan,

mwiz vm Y Jan. 16, 1945. v c. w. SOLDAN I 2,367,379

SELF-LOCKING THREADED DEVICE Filed Oct. 25 1944' 5 Sheets-Sheet 5 ClmwnceWSpldan panion threaded elementf a .line I'lll of .Figure 6; I I Figure 11 is a greatly enlarged v'ievv showing an 1 I assembled floating thread member and cap screw, 56'

Patented Jim-7161 1.9-4.5-

UNITED ,smes I PATENT OFFICE 2,367,379 I V I SELF-LOCKING THREADED DEVICE Clarence W. Soldan, Baltimore, ,Md., assignor to Crown Cork '& Seal Compan lnc 'Baltimore, Md., a corporation of New York Application October 25, 1944, Serial No. 5 0,221

26- Claims.

the cap screw. being indicated in dot and dash.

lines; I

Figure 12 is a view of the floating thread mem- 4 her of Figure 11 as viewed from th direction indistruction that when they are used with companion threaded elements, neither element can movewith respect to the other due to vibration.

Another object of the invention vis. to provide sat-locking threaded elements of such design that they can be readily assembled and threaded into companion elements. r

Other objects and advantages of the invention will beapparent from the following specification and accompanying drawings ,wherein:-

Figure 1 is an elevation. of a capscrew constructed in accordance With the present inven-. tion;

Figure 2 is a view showing the leading end of the Figure 1 cap screw in side elevation, a floating thread member included in the present invention being omitted from the view;

Figure 3 is Figure 2;

Figure 4 is a transverse section ion the lined-4 ofFigure2;- II

Figure 5 is an endview oi the cap screw of Figure 2, the view being taken from .the right of Figure 2; I

an axial section onthe line 3-3 of Q a modified form of floating thread member, the

I capfscrew being indicated in dot and dash lines.

cated by the arrow a in Figure 1-1;

Figure 13 is a side view of the floating thread element viewed from the direction indicated by the arrow b of Figure 11;

'Figure 14 is a radial sectional view of the floating thread 'member;

Figure 15 is a. side elevation of a cap screw or modified form; r

Fi re 16 is a'trans floating thread member shown in Figure l'ljand Figure 171s a greatly enlarged view showing the modified cap screw of Figure ldassembled with Referring to Figures 1 to 14, the numeral I 20 designates a cap screw constructed-in accordance with the present invention, the cap screw being provided with an [American National coarse thread indicated atz.

v National Bureau of Standards Handbook H28..

' shallbe hereafter knownas the American National thread;

Figure '6 is aview showing" the cap screw and l j floating thread member in side elevation and.

Figure 6a is a transverse section on the line 6a- 6a of Figure 6i I Figure 7 is a view similar to Figure 6 but showing the cap screw 'fully' threaded into the com- Figure 7ais a transverse sectional view on the line la-1a of Figure 7; I I Figure 8 is a view. similar to Figure 6-but showing the cap screw being unthreaded from the companion element;

Figure 8a is .a transverse tic-8a of Figure 8; I I I Figure '9 is an end" view of'the leading end of the section on the As shown-best in Figure g2, the leading end of the cap screw has a portion of the threads re-.

moved therefrom as indicated at 3,- with the result:

that the thread bf'the cap screw begins at the point 4 which is spaced from the point at which the thread would normally begin on such a cap screw. T he leng'th of, thread 5 beginning at point I dis of'extrem'ely short extent-and terminates in a concave abutment in stem axially extending.

groove 6. Beyondgroove 6, one helixor the thread 2 is entirely omitted and, instead, a helical groove 6 is substantially semi-circular in transverse section, the 'curvature ,or radius of the g'roove-beingoi an-outline hereinafter discussed. However, asshcwn iii-Figure 4, the maximum cap-screw with. the floating threaded member applied thereto in the position illustrated in Figure 6?? I Figure 10 is atransverse sectional view onthe depth of the axial groove firalong a'line extending diametrically of the screw, is the sameas the substantially corresponding to the height to which the threads 2 extend abovetheroot diamv verse section of the modifiedconcave curve.

eter 9. The bottom wall l6 of the helical groove 1 isconcentric with the axis of the cap screw, except as hereinafter described.

The helical groov I must be regarded as extending into axial groove 6 in that the end III of thread 5 on one wall of the axial groove forms an abutment at the leading end of the helical groove.

Also, the end ll of the thread 2 beginning oppo site the wall of axial groove 6 forms the trailing end of helical groove I in that it forms an abutment at the trailing end of the helical groove.

Asbest shown in Figure 4, the helical groove 1 includes a restriction 20 in the form of a radial projection or enlargement on its bottom wall 16.

The restriction 20 includes an outer or top surface 2 I concentric with the axis of thecap screw which, in a .75" cap screw, for example, would extend approximately 25. An incline 22' also forming part of the restriction joins the bottom or inner wall it of helical groove Ito the surface 2| of the restriction. Inclined surface 22 is-prefscrew so that the incline will be a relativelyfiat It' will be noted that the incline 22 forms the leading sid of the restriction 20 and that the trailing side of the restriction is formed by the axial'groove-i.

As best shown in Figure .4, the diameter on which the surface 2| of restriction 20 is formed is less than the root or minor diameter 9 of thewalls 21, the band is provided with a thread 28 of the-same cross-sectional conformation as the erably formed by a'radius based outside the cap mum of .75".

threads 2 of the cap screw I. While member 2'5 is of generally helical form, it is not of uniform diameter throughout its length. For example, as clearly indicated in Figure 11, both ends 29 and threads 2 of the cap screw 7 when moved in the opposite direction, the leading end-29 of member 25 will come into abutment with the end ill of the short length of thread 5. Before the trailing end 30 of member 25 can contact with the leading 'end ll of the threads], it must move over the restriction 20. 7

For the purpose of setting forth the general form of a typical self-locking element of the present invention, it may be pointed out that a .75" American National coarse thread cap screw constructed in accordance with the present invention to have a Class 2 fit, will have the base wan 16 of its helical groove I formed on a radius of .249", while the surface 2| of restriction 20 will be formed on a radius of .285". In accordance with standards specified in said Handbook H28, the minor diameter of the screw I, i. e., its dsia ineter at the root 9 of the threads would be 2 3". I

It is to be noted that a .75" American National coarse thread cap screw designed to have a No. 2 fit with a female element may have the major diameter of its threads a minimum M17372",

i. 'e.; a radius of .3686", as indicated in Figure 11 of the present application. The female or nut element to be used with such a' screw would have the root or major diameter of its threads 9. mini- In other words, with a No. 2 fit, and with the screw of minimum tolerance major diameter, the companion elements would have a diametrical play of .0128".

The member 25 to-be used with a .75" Ameriecan National coarse-thread screw such as indi cated by the numeral I would beof a radial thickness of .0929" as indicated in Figure 14. Figure 11' gives radial dimensions for a member 25 provided for use with such a .75" coarse threaded cap screw having a No. 2 fit. It will be noted from this figure that the member 25 is symmetrical in that the two halves thereof on 0D- posite sides of the diametrically extending lines C-C are identical in configuration. More particularly, within each of the arcs G, which comprise the central portion of member 25 and extend for substantially 90 in each direction from the righhhand end of the line 0-0 in Figure 30 are bent ordeflected inwardly-irom'a helix so that the innermost point of each end is closer to thediametricaliy opposed point on the surface 26 than'is the case with any other two diametrically opposed points on the inner surface 25.

The member 25 is formed of spring steel to be bodily resilient, though it has sufiicient rigidity to exert strong pressure against any efiort to bend it inwardly from the normal form illustrated in Figure 11 and, when bent inwardly, will exert considerable force outwardly.

' Figures 6 and 6a show the band 25 fitted in the helical groove of the cap screw I, and it will'be noted that the end 29 forms the leading end'of the band wane the opposite end an forms its trailing end. The diameter of the inner surface 25 of-the member 25' is sufliciently larger than the diameter ofthe surface l5 of groove 1 that memher 25 may move diametrically and circumferentially in the groove 1 when not within a com-'- panion threaded element. Because of this, the

member 25 can be regarded as a floating thread onelement 2 as referred to above. with regard to circumferential movement of member 25 in' the groove 1, it will be clear-from Figures 6a to 8a that member 25 can only move clockwise in these figures to such-extent that its trailing end 30 will abut against the leading endll of the 11, themember 25 has an outside radius of .3839" and an inside radius of .291". Then,

throughout the arcs H extending for 44, the out- ;side radius is formed on a curvature of .367

centered on the lines G which form. the outer limits of the arcs G. From the lines .H' defining the ends of the arcs H, the outside radius of member 25 is formed on a curvatl'lre of 3 based on each lineI-I'. By reason of the above-described inward deflection of member 25 adjacent its ends, its inside radius adjacenteach line H' will approximate .285", i. e., the radius of restriction 20 of screw I. The purpose of this is hereinafter described.

As is clear from Figures 4 and 5, the axial groove 6 is curved in transverse section and Figure ll shows the radius which may be used for this curvature. By having groove 6 concavely curved, instead of with straight side walls, it

can be formed by a single millingoperation. In

be noted that the member 25, throughout the ,as a symmetrically distorted helix, or a two, arcs G, is normallyfof greater outside radius than the radius of the root or major diameter of a companion female threaded member to .receive screw I That is, throughout the 180 of member. 1

25 encompassed in the arcs G, member 25 is of a bar is of .375" radius.

.3839" outside radius, whereas the motor major a diameter of a companion female threaded meme Figure 11-clearly indicates that member 25,. when unrestricted, has-an,

outside radius throughout the major portion of its length which is greater than the major radius of the threads of screw I. a It will also be observed "the member 25 might be described as a'helix which is flattened along a line extending between 3 its two ends, as is the case with the line 0-0.

Stated another way, member 25 may be described helix having its ends' bent inwardly.

The manner in which the floating thread member" 25 of Figures 1"to 14 performs a'locking funcand 6a show the threaded element! being initially threaded-into -a machine body or' base 35 pro As shown in Figure 6a, the screw I, being righthanded, .wilhrotate in the direction of the arrow of Figure 6a, thereby rotating and moving to the right as indicated bythe bent arrow of Figure'6. Before the member 25 is engaged with the threads 36, its trailing portion 3|] should be positioned in contact with the leading end II of the' Under these circumstances, the 'resiliency'of the f om Figure 11 that.

Even extreme vibration will not cause member I to unthread'with respect tothe threads 3'.i because any unthreading rotation of screw I from the position shown in Figures '7, 7a, and 11 (and, clgckwise with respect, to those 'flgures) 1; will simply cause the restriction 20 atthetrailing end ofgroove I to move into closer contact or engagement with thesurface 3|. of member 25. Such movement'would have the effect of bending the inwardlyv curved trailing end 30 outwardly from the position shown and this could not be accomplished by vibration alone.

, If it is desired to remove the cap screw I from the element 35, a wrench of the usual form and size is applied to the cap screw and, upon the application of strong force to the wrench, the cap screw may be reversely rotated in the direction tion in cooperation with the screw I and a com panion threaded member is as follows: Figures 6 ,v-ided with American National coarse threads 36.

member 25 will enable it to contract somewhat.

Generally speaking, this contraction will occur by inwardspringing of the member 25 throughout allof the portion thereof other than the end 30 and the portion adjacent that end which is lying upon the restriction 20 as indicated in Fig- -"ure'11'. -This inwardspringing will cause end 29 to move slightly counter-cl'ockwisein groove 1 as' viewedin Figure 11 and may even result in bend- I ing end 29 outwardly,- thereby increasing the tension exerted on threaded element 35..

of the arrows of Figures 8 and 8a. The operation of the member 25 under these conditions is as follows: Because of its bodilyresiliency and tendency to expand so that the greater portion of its length will be of larger outside radius than the diameter of-the threads 36 of companion element 35, member 25-will be prevented from ro-.'

However, with thetating in the element as. proper force applied, the member 25 will bend adjacent itsendf portion 30 so that the restriction 2llwill' move beneath the surface 3|. When the inner tip 32 bears upon the surface 20, the cap screw can then be turned to move the end 30 off restriction 20 so that the screw I will occupy the position with. respect to member 25illustrated i in Figure 8a. In this position, the opposite end 29 of member 25 willlie in the axial groove Ii to abut against the surface ID of the groove so that the member 25 must then unthread with element I. While the 'oversized dimensions and resiliency of member 25 will still cause it to exert a strong drag against the threads 36 during unthreading rotation of the cap screw in the direction of the arrows of Figures 8 and 8a, the cap screw can be unthreadedwith the application of proper force to thewrench. 1

Because of the fact that the member 25 of Figures 1 to 14 is ofsymmetrical form, it is immate-,

rial which endof member25 is positioned as the leading en d129 when it is placed upon a screw I This saves time in the assembly of the floating 1thread member upon screw I. 60

3 at 'the end of a cap screw enables the floating thread member to be placed inthe helical groove I when the member.2-5 is sprung open for as- Figures 7 and ia. show the cap screw- I fully threadedinto the element 35, and it will be observed that the member 25 still occupies the position relative to screw I which-is illustrated in The provision of an unthreaded area such as sembly; Because of the force rewired to spring the floating thread member open, it is impossible for the memberto fall from the element I or even be removed except by special tools. Therefore,

Figure 6a because threading rbtati'on of screw I. I

keeps shoulder I I in contact with the end surface of end 30 of band 25. l r

The strong force exerted outwardly against prevent member 25 ,fromhaving 'unthreading movement with respect'to the threads 365 Hence, u if screw 1 is to turn in the direction of the arrow designated fTounthread" in Figure ll it must turn relative to the member 25. lnotherpwords,

yibrationcannot cause member 25 to turn with element I .in -an unthreading direction. Infact,

member 25-is, in effect, a permanent part of the 'screw' I.

'- It will also be observed that because the restriction 20 is always closely adjacent the inthe threads 36 'by reason of the fact that member 25 is normally oversiz'ed with respect thereto throughout the greater portionof its" length will markedfTounthread in Figurell mustbring I member 25 and'elementfll can only turn together in-an uhthreading direction under the conditions described belbw and involving the. application of extremelystrong turning force to the element I.'

wardly formed surface 3I at the trailing end 30 of mmber 25, there can be a minimum of turning movement of screw I with respect to member 25 under'vibration. That' is,fthe slightest movement of screw Lin the direction of the arrow the restrictioni'llintoeven closer contact with the inwardly curved surface 3|. Therefore, whenever a screw has been moved to the desired position, it can have no play in either direction, 1. e., it.isflrmly locked against further possibility of movement as soon .as t "reading move-. ment by the operator has stopped.

. In order to enable the floating thread member ber 25 too sharply during assembly with the cap screw.

It has been found that an important reason With the above definition in mind. the character P in Figure 11 designates a point on the pitch diameter of the cap screw I as well as the companion threaded element or nut 35. The character P25 in Figure 11 designates a point on the pitchdiameter of the portion of floating threaded element 25 which is within an arc G and, therefore, has both a larger outside diameter (or radius) and a larger pitch diameter than that inwhy a floating threaded member such as disclosed herein and in said Harding application resists movement from a locked position such as shown, for example, in Figure 11, is the following: when an unthreading tendency is initiated, either by vibration or by intent of an operator, the resultant movement of a locking end such as 3| with respect to a restriction such as imparts a force to the member whereby the latter tends to straighten out throughout its entire length. As a result, a tremendous outward and radial pressure is applied by the member 25 to the threads of the companion element 35. This force is greatly augmented throughout the portions 01 member 25 which have a diiferent, viz., larger, radius than that of the female element 35, as is the case with the portions of member 25 embraced by the arcs G in Figure 11.

I have found that the force exerted by the portions within the arcs G is so great that the size of the member 25 can be reduced according to various procedures hereinafter discussed, and that the resistance to unthreading movement will still be so high that it will be adequate to meet foutside diameter which is greater than the outside or major diameter of cap screw I. It has also been pointed out that when member 25 is not within a female threaded element 35, the outside diameter of portions of member 25 is normal- 1y larger than the root or major diameter of a female threaded element 35, In short, the floating threaded element 25 of Figures '1 to 14 as hereinbefore described may be termed oversized in that portions thereofnormally have .an out-- side diameter which is larger than the major diameters of the threaded elements I and 35. Obviously, the portions of member .25 which are oversized in outside diameter are also oversized with respect to pitch diameter.

In connection with the above use of .the term pitch diameter, reference is made to the definition of the pitch diameter ofa straight screw threadwhich appears on page 2' of the abovementioned Handbook H28, which definition reads as follows: .Pitch diameter-On a straight screw thread, the diameter of an' imaginary cylinder, the surface of which would pass through the threads at such points as to make equal the width dicated by P. It will be observed that since point P25 is spaced a greater distance from the axis of cap screw I than point P, the pitch diameter (or radius) of the portion of member 25 within arc G is larger than the pitch diameter or radius of the cap screw I and element 35.

. It also will be observed that, according to the abovedefinition, a thread may'be truncated in section, and thereby have a broader crest, without its pitch diameter being reduced.

I have found that in numerous instances it is only necessary that the pitch diameter of portions of member 25lbe larger than the pitch diameter of screw I and female threaded element 35, and that so long as this relationship is retained, the outside diameter of member 25 may be reduced. The dotted lines 25a superimposed on the floating thread member 25 of Figures 11 and 14 indicate how this member might be of smaller outside diameter'so long as the pitch diameter indicated by P25 of portions thereof is greater than the pitch diameter P of elements I and 35.

It will be observed thatmaking the line 25a the outer perimeterof member 25 simply means that the depth of the thread on 25 is decreased and that no other dimension of member 25 is thereby changed. In other words the portions of the tapered side walls of member 25 shown below line 25ain Figure 14 will still hear on the female thread of element 35 with the same force such portions exert if the member 25 has a thread of standard depth. I

With the outside diameter of the floating thread member 25 reduced'to conform to line 25a as described above, that is, if throughout its perimeter, member 25 is smaller than the major diameter of either screw I or element 35, an adequate locking effect will still be obtained if portions of. member 25 have their pitch diameter (or radius) largenthan the pitch diameter of elements I and 35. -11 member 25 formed in this manner has the advantage that it can be more readily threaded into a female threaded element 35. Nevertheless, as indicated above, its tapered side walls embraced within the arcs G in Figure 11 include entirely adequate surface to exert and maintain thenecessary pressure upon the opposed tapered walls of the thread of female element 35 when member 25 has a straightening-out tendency applied thereto as hereinbefore explained;

'Another'way in which the oversized floating thread member 25 of Figures 1 to 14 can be reduced in outside diameter or radius is by reducing its inside diameter or radius and, at the same time, maintaining its section substantially the same as shown in solid lines in Figure 14.

A member 25 having the last-mentioned characof the threads and the width of the spaces cut by the surface of the cylinder.-

of the companion element.

gaging portion atits trailing end and alsohav- 14, the outside radius throughout the arcs G will I be. approximately .373". Therefore, the greatest outside diameter (along lines G'G in Figure H) will be approximately .746" instead of .766"

The oversized" floating thread member: 25

disclosed in Figures 1 to'14, i. e., the form where J trated therein has, its leading end formed'in a Y 1065 spring steel, or even greater hardness, it is preferable .t'ohave the outside diameter of the less than the outside diameter of the, screw as above described. Also, in order to meet actual working conditions, it is frequently desirable to use an undersized washer because of the follow.- ing circumstances. stated, a .75 American. Nationalcoarse thread capscrew designed to'ha'vea Class 2 fit with a female element is'finished to make the minimum major or outside diameter of its threads .7372".

However,--'t he maximum outside or major diameter of the cap screw threads which is permitted is .75. On the other'hand, the female element to be used with such a screw may have a mini ing the helical groovebf the capscrew provided with a restriction at its trailing end. 7 Referring to Figure 15, the capscrew 50 illusmanner generally similar to that of the form hereinbefore described, except that the axial groove 5I has-a flat surface 52 extending parallel to a diameter 'of the cap screw. Also, the inner end 53 of groove 5| may be rounded. A, groove of this conformation can be formed by cutting a single milling operation.

The dimensions of the cap screw 50 are hereinafter set forth connection .with the description of the floating threaded member to be used therewith.

Figure 16 is a cross-sectional view of the floating thread member 54 designed for use with cap screw 50, the dimensions being thoseintended member.25, throughout the length of the washer,

As has been hereinbeforefor use with a .75" American National coarse thread cap screw designed to have a Class 2 flt with a female element. As shown in Figure 16,

member 54 would have a thickness of .083"

thereby being narrower than the width of the helical groove 55, which is,\ .1".. Theinclined or, threaded portion'of member 54 has its walls of v the same tapered conformation as a thread of mum thread base or major diameter approximating .750 inch If a screw of maximum diam eter is used-with a floating thread'member of the oversized. type,an extremely tight flt with the female elementfwill result. Therefore, it"is frequently desirable to use a floating thread member of the undersized type. However, in some situations, for example, when it is assured that there will be a diametric play of- ;013 inch between the screw. and the female element, .an oversized floating thread member is entirely practicable. i

It maybe stated at this point that the matter of. whether an undersized or oversized floating thread member is used does not affect the locking diameter reduced to the line 25a in Figures 11 and 14, but its pitch diameter 'and'inside radii kept the same as illustrated in Figure '11. That is, whenany unthrea'ding tendency is applied, the floating thread .member tends to straighten out, thereby exerting force against the female member.

the threaded element with which itis to be used. The width of the flat outer portion or. crest would be .018". Therefore, thread member 54 is truncated to have a different widthof crest from a standard thread section, which latter would be .0125".

Figure 1'7 shows the floating thread member '54 of Figures '1-5 to 1'7 mounted upona cap screw 50, the cap screw .being illustrated in dot and dash-lines. The base wall or inner wall 55 ofhelical groove 56' of' cap' screw would be .25"

in radius throughout the larger portion of its length. This groove would be a true helix as is the case with the corresponding groove of- Figures 1 to 14,. At its leading end 51, helical groove I axial groove 5|, the latter groove being positioned M4" from the axis of the cap screw and having,

a width vof The trailing end 58 of helical groove 56 is provided with a restriction 59 formed on a radius of .281", this restriction terminating characteristics of the member for the same reasons as have been stated above in connection with the use of amember having its outside at its trailing end at-the' flat inner wall of the axial groove 5|. 59 includes anjinclinedwall 60 which blends into 56 would merge into the flat inner wall 52 of the The leading side of restriction the .25" radius of the major portionof the base I wall 55-of helical groove 58. f

Figure 17 shows the flat trailing end portion 61. of floating thread member 54 positioned in the axial groove 5| of the cap screw, as' would be the case when the cap screw'isbeing threaded An advantage of havin the washer undersized is that once it'has been moved to the un-i-i locked position, it can be readily unthreaded because it exerts no marked drag upon the threads Figures 15 to 17 disclose an-undersized floatin thread member of a third type. In addition, the' ber 54 would be /64" or .266".

above, the radial thickness of member 54 is .087", its outside radius throughout arc'K would be structure shown in Figures 15 to 17' includes a [non-symmetrical floating thread. member and also may have a straight trailing end'instead of a curved trailing end as indicated at 30 in the form of Figures 1'to'14. However, the structure hereinafter described in connection with Figures 15 to 1'? has thecharacteristic common to the form of Figures 1 to 14 of having .thefloating into a female element or-isin locked position 1 Member 54 has the tip of its' flat or looking end 6| positioned A" from the tip of the therein.

leading, end. 62 and throughout an arc extendingapp'roximately 110 therefrom,'. and indicated.

by the arcuate line K, the inside radius of mem- V endof arc K to line L positioned at the begin.-

thread member provided with a restriction en,-

ning of-the flat portion 6|, the inside radius of member 54 is 3%" or .281. Therefore, the outside radius of the arcuate portion designated by the line L is .368".

Because the maximum major diameter of a /4" American National coarse thread cap-screw designed for a Class 2 fit is .'75,-or' .375'! radius, whereas the portion of member 54 indicated by Since, as stated From the radial line K designating the.

will be observed that this portion of member 54 is of smaller radius than the outside or major radius of the cap screw on which it is to be used. With .regard to the remaining curved portion of member 54, l. e., that portion indicated by the arc L, this has an outside radius of .368" and, therefore, is only slightly undersized. However, as shown in Figurel'l, the diameter of member 54 taken along a line passing through its leading -end 60 is approximately .721. Since-this diameter is a maximum diameter it will be clear that the maximum outside diameterof member 54 under normal conditions will be less than the maximum majondiameter of' .75"' of the cap screw under discussion. The dimension between portion, as well as a portion bent inwardly out of the helix, just as is true of the corresponding curved end portion of the floating thread members of Figures 1 to 14.

With the device of Figs. 15 to 17 in the locked position indicated in Figure 17, i. e., with the flat 2,867,379 arc K has an outside radius of only .353",-it

another way, the length of member 54 measured ina circumferential direction, is not highly critical. The fact that a critical tolerance need not be maintained at this point is advantageous because such a tolerancewould be difficult to maintain. 'Also, in the manufacture of the cap screw, the critical tolerances are only those within the area occupied by axially extending groove 5 I. and

' restriction 59. These tolerances can readily be controlled during manufacture.

' The devices of the present invention obviously require no special tools to operate them to locked position or to assist in unlocking. In addition, there are no parts which can deteriorate, as ocours with looking devices formed of compressible material and, in use, the floating thread is entire 1y enclosed so that it cannot be tampered with. The floating thread members are also of such design that they cannot becomebroken during operation and cannot mar the threads of a companion elem'ent.

It will be understood that the dimensions of I the .75 cap screws of the present invention set forth hereinare merel to disclose the dimensurface at its trailing end 6| bearingagainst flat that direction, whether the force be applied by.

an operator or by vibration, will. immediately cause the flat surface 52 of an axial groove 5| toexert an outward force at B in Figure 17 and in the direction of the arrow B, thereby urging and wedging the locking and trailing end of the floating thread member 54 against the threadsof the female element. At the same time, because re- 40 striction 59 is bearing on the inner surface of member 54, the restriction 59 will move even more closelyagainst the inner surface of the member 54 to apply a pressure acting to bend the locking member outwardly. As a result of these forces which act instantly upon any unthreading move-. ment of the cap screw, back-lash and the possii-bility of unthreading by vibration are eliminated.

It is.also-to be noted that when the above forces areapplied, a straightening out tendency is applied to the entire member 54 as has been sions used in an element of a given size and torque required and that the invention is applicable to threaded elements. of all sizes. Furthermore, the dimensions stated for the .75 cap screws under discussion may be varied for even a screw .of such size according to the conditions under whi-ch the invention is to be used.

4 It will be clear that the invention i applicable to threaded elements of numerous types other than cap screws.

"The terminology used in the specification is for the purpose of description, the scope of the inventlonbeing indicated in the claims.

Iclaim: I

1. In a self-locking threaded device, a threaded element including a helical groove having a pitch substantially, corresponding to the pitch of its threads, a substantially helical member mounted in the groove, at least a portion of said member normally being of a diflferent radius from the radius of the thread of said element, said hell-cal member being bodily resilient to bend and thereby conform to a companion threaded element engaged by said first element, but being sufficiently rigid that it will exert radial pressure upon the companion element-to resist turning movement pointed out above in connection with the other forms disclosed herein. Therefore, member 54 will be urged outwardly'againstthe threads of the female element.

However, upon the application of suitable force to the cap screw, the restriction 59 can be moved in the direction of the arrow A and beneath the One such advantage arises from the fact that the points of the locking ring on which manufacturing tolerances must be closely observed are all with respect to the latter, and coactine. means respectively carried by said' threaded element at the trailing end of the helical groove and at the trailing end of said helical member whereby the latter will be more strongly urged into contact with a companion threaded element upon unthreading movement of said first threaded elewithin a small area of the locking ring. Thesef tolerances involve only the length of the flat; portion BI, and the extent to which it is oil'set with respect to the adjacent curved portion of the member. These tolerances are not: dimcult to maintain.- It will be noted that the distance be--.' tween the two ends of the member 54, or, stated 4. A self-locking threaded device of the character described in claim 1 wherein the greatest radiu of" said helical member is greater than. the major radius of said threaded element.

5. In a self-locking threaded device, a threaded element including a helical groove having a pitch substantially corresponding to the pitch of its threads, a substantially helical member mounted in-the groovaa threadon said helical member a ,2,86'i',62'9v of different radial sectionthan the thread of said elements, at least a portion of said member normally being of a diflerent radius from the radius of the thread of said element, said helical engaged by said first element but being .sufflmember being bodily resilient to bend and there- .by conform to a companion threaded element ciently .rigid that it 'will-exertir'adial pressure upon the companion element to resist turning helical member adapted to engage upon unthreading of said first element with respect to a companion threaded element.

- 7 6. In a self-locking threaded device, a threaded element including a helical groove having a pitch substantially corresponding to the pitch of its 7 [10. In a self-docking threaded device, a threaded element including a helical groovehavinga 'pitch substantially corresponding to the pitch of said member including a portion at, its trailing its threads, the trailing end of said groove ter.-Q minating in a substantially radially. extending shoulder, a radial projection adjacent the trail- 1 mg end of said groove, a helical member mounted in the groove and of less length than the latter,

end adapted to engage the groove restriction upon unthreading movement of the threaded element with respect to a companion threaded element. 1

' 11. Ina self-locking threaded device, a threaded element including a helical groove having a pitchsubstantially corresponding to the pitch-of 1 its threads, the trailing end of the groove terthreads, the groove having a restrictionat its trailing end, a substantially helical member mounted in the groove, at least a portion of said.

lnember normally having a pitch diameter dif ferent from. the pitch diameter of. the thread of said element, said member being bodily: resilient to bend and thereby conform to a companion threaded elementengagcd by said firstelement, but being sufliciently rigid that it will exert radial pressure upon the companion element to strongly resist turning movement with respect to'the' latter, said helical member being.

its trailing end to engage the restrictiomin the of said first element with respect to a companion threaded element:

7 provided with an inwardly deflected portion at groove of said first element upon unthreading 7. In a self-locking-threaded device athr eadedmally having a pitch diameter different from the pitch diameter of the thread ofsaid element,

thereby conform to a companionthreaded ,ele-- ment engaged by said first element, but being minatin-g in a substantially radially extending shoulder, a radial project-ion adjacent the trailing end of said groove, a helical'member mounted in said groove and of a length less than the length. of the groove, said member having its the companion threaded element. 1

12. In a self-locking threaded device,a threaded element including a'helical-groove having a element-including a helical groove h'avingfl- Pitch -swbstantially correspondingiio the pitch of its threads, the groove having a'restricton therein, fa substantially helical member mounted in the groove; at least a portion of said member-norsufficiently rigid that it will exert radial pres-L *sure upon the companion element 'to strongly ter. said groove restriction being adapted to engage said member upon unthreading of said resist turning movement with respect to the, lat "5o first elem t with respect to a companion thread ed elem nt, the greatest diameter of said helica member. being lessthan the major diameter of.

said first-named threaded element.

a. In ase'lf-locking threaded device, a threaded substantially corresponding to .the pitch of its element including a helical groove having a'pitch pitch substantially corresponding to the pitch of its threads, the groove having a restriction therein, asymmetrical substantially helical member. mounted in the groove, said member extending.

through approximately 335 and having an outside radius throughout substantially 180 which is greater than the greatest opposed diameter of a companion threaded elementso that said memher will not turn respect to 'a companion fthreaded element upon vibration, and cooperating means in-the groove and upon the remain ing portion 01 the len thof said member adapted "to engage and further urge said member into locking relation wit .a companion .threaded 'e 1e, ment upon unthreading movement of said grooved element with respect to the com-panion threaded element.

13. -In a self-locking threaded device, a threaded element includinga helical groove having a pitch substantially corresponding to the pitch of. its threads, the groove having a restriction therein, a symmetrical substantially helical member 'mounted in the groove, said member extending through approi'iimately 335 and having an out- 0 side .radius' throughout substantially 180?- which is greater thanthe greatest opposed radius of .a

companion threaded element, the'remainder of the length of said memberg having a radius less than the greatest opposed diameter of acompanion groove; said member including end portions bent inwardly out of the helix, said groove restriction being adapted to engage one of said bent portiorrs upnn unthreading of said e em nt with respect to a companion threaded element. I

9. In a se f-locking -threaded device. a threaded element includin a helical groove havin a pitch substantially corresponding tothe pitch of its threaded element, and coacting enlargements on the last mentioned portionpf said member and in the groove adaptedto come into contact upon unthreading movement. of said threaded elementwith respect to a companion threaded element to urge said portion ofsmall radius-into contact threads a helical groove of 'a pitch substantially corresponding to the pitch of its threads, a subthreads; the groovehaving an outwardly nro- .iectin-g restriction therein at its trailing end a substantially helical member mounted in the groove, said member having an inwardly deflected portion on its trailing end adapted to enga e the restriction, upon unthreading of said element with respect to a companion threaded element with the companion element.

14. A self-locking screw having; within its stantially'helical member mounted in said groove, said helical member'beng of less length than the groove and being fr ely movable lengthwise of the groove, said helical member having portions curved on. radii of differentlengths, the radius 'ofcurvature of .the central portion of said-member providing an arcsubst'antially concentric in respect to the screw and the radius of curvature of the end portions of said member providingan arc eccentric in respect to the screw.

15. A self-locking screw having within its threads a helical groove of a pitch substantially corresponding to the pitch of its threads, a substantially helical member mounted in said groove,

said helical "member being of less length than the groove and being freely movable lengthwise of the groove, said helical member having portions curved on radii of different -lengths, the radius of curvature of the central portion of said member providing an are substantially concentric in respect to the screw and the radiusof curvature of the end portions of said'member providing threads, said element including a flat surface at the trailing end of the groove lying ina plane substantially parallel to a diameter of the an arc eccentric in respect to the screw, and the.

outside diameter of an appreciable portion of said member being sufiioiently greater than the outside diameter of the threads of said screw to'take up all play between the screw and 'a' companion female element, such as a nut.

threaded e1e'ment,a substantially helical member mounted in the groove, said member including i ment, the groove having a restriction therein ad- 16. In a self-locking threaded device, atnr aded element including a helical groove having a pitch substantially corresponding to the pitcli of its threads the groove extending through substantially 360, a radial enlargement adjacent but spaced from the trailing end of the groove, both ends of the groove terminating in substantially radially extending shoulders, a substantially hel-- ical and bodily resilient member mounted in the groove, said member extending through approximately 335 throughout substantiallyl80 and in its central portion which is normally greater than-the greatest opposed 'diameterof a companion threaded element so that said member will not turn with respect to a companionthreaded element upon vibration, the trailing end of said member being adapted to abut against the trailing end of said groove during threading movement of said grooved element with respect to a companion threaded element, said member being provided with inwardly curved resilient portions at both ends jacent the flat surface, a substantially helical member mounted in the groove, said member including an end portion bent out of the helix to lie straight and bear upon the fiat grooved surface in locked position with respect to a companion. threaded element.

22. In a self-locking threaded device, a threaded element including a helical groove having a pitch substantially corresponding to the pitch of its threads, said element including a flat surface at and having an. outside radius;

the trailing end of the helical groove lying in a plane substantially parallel to a diameter'of the ..ber including an end portion bent out of the helix to lie straight and bear upon the flat grooved surthereof, the restriction in the groove being adapted to move beneath the inwardly curved portion at the trailing end of said member upon unthreading movement with respect toa companion element and to thereby force said trailing' end outwardly into closer engagement with element; including a helical groove-having a pitch substantially corresponding tothe pitch of its threads, said element including a flat surface at one end of the groove lying in a plane substantially parallel to a diameter of the threaded element, a substantially helical member mounted in the groove, said member including an inwardly deflected end portion to bear upon the flat grooved surface in locked position with respect to a companion threaded element.

18. A self-lockingthreaded device of the character described in claim 17 wherein the inwardly deflected portion of said helical member is straight. j t 19. In a self-locking threaded device, a. threaded element including a, helical groove having a pitch substantially corresponding to the pitch'of its face in locked position with respectto a companionthreaded element.

23. In aself-locking threaded device, athreaded element including a helical groove having a pitch substantially corresponding to the pitch of its threads, a substantially helical member mounted in the groove, at least a portion of said member normally being of different radius from the radius of the thread of said element, said helical member being bodily resilient to bend and thereby conform to a companion threaded element engaged by said first element, but being sufliciently rigid that it will exert radialpressure upon the companion element to resist turning movement with respect to the latter, and coacting means carried by said threaded element and said helical member whereby the latter will be more strongly urged into contact witha companion threaded element upon unthreading ofsaid first threaded element with respect to a companion threaded element, said helical member'having a thread of less than standard depth, but which is otherwise of the same transverse section as "the thread of said first named threaded element.

24. A'self-locking threaded device of the characteridescribed in claim 8 wherein said helical member is provided with a thread of the same section as that of said threaded element and the greatest radius of said helical member is less than the major radius of said threaded element. 25. A self-locking threaded device of the character described in claim 8 wherein said helical member is'provided with a thread which istruncated in radial section.

26. A self-locking threaded device of the character described in claim 5 wherein said helical member is provided with a thread which is truncated in radial section. i

. CLARENCE W. SOLDAN.

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