US 1523225 A
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A. N. LUKENS HELI CAL SPRING Filed Oct. 18, 1922 A TTORNE Y5 Patented Jan. 13, 1925.
KPH-Q PATfEN ALLAN N. LUKENS, 'OFELIZABETH, NEW JERSEY.
Application filedjQctober 18,1922. .Serial No. 595,321.
To all whom it may concern:
;Be it known that I, ALAN N. :LUKENS, a citizen of .the United States of .America, residing at Elizabeth, in the county of Union and .State'of New Jersey,hav.e invent-ed certain new and useful Improvein-ents-in .Helical Springs, of which the .fol-
lowing is a specification.
.inventionis to providefa compression-spring affording greater strength, in a1spr1n-gof given over-all diameter, lengthand number of coils, thanis possibleto secure in=agspring ofconventional type, while at thesame time affording equal or -greater-clearance between .the coils toobtain suitablerange and ease'of action. Other advantages Wlll be hereinafter pointed out, or are disclosed in the accompanying drawings, in which Fig. 1 isan axialsection through ahelical pring in which my invention isembodied inone form;
Fig. 2 is aplan view thereof;
Fig. 3 is an axial section showing the spring compressed to solid;
Fig. 4*. is.a,partial development.of therod from which zthe spring is .made;
Fig. 5 visa cross section thereof; and
Figs. 6,7 and 8 are views corresponding to Figs. 1, 2 and '3, but of a conventional spring.
,lVhile the present spring is by no means limited in its utility to service as a draft or supporting spring for railway cars, it has a particular utility in this application by reason of its great strength .withinlimited dimensions.
The developments of modern railway stock have been along the lines of increasing weight and burden, without a corresponding increase in the space to be occupied by springs. The amount of work to be done by springs has ,grown in excess of the power of any conventional spring that an be mounted in the available restricted space. Frequent spring failures, great damage to rolling stock, delays in transportation, and the high costs incident thereto, have resulted.
The present invention provides a helical spring which can be mounted in the avail able space, and has the power to do the work required, while it can be manufactured and marketed at low cost.
It is well known to those familiar with jtheart, that the number of turns or convolutions that can be used in a helical spring is regulated by the allowable solid length divided by-the thickness of the bar or wire.
The loads imposed upon the springs in modernirailway equipment areso heavy that bars or wire of large size must be used to support the load; but the possible number of turns :of such large bars, when they are ofconventionalcircular section, is insuffi- ,c1entt-o provide proper resiliency with suitable range and easeof action. Moreover,
if-zsuch heavy bars of conventional circular section are employed, the coils approach each other so closely that, in service, they are repeatedly driven solid and the blows so -delivered result inn-resetting of the particles of-metal. in the bar-orspring, whichcauses ra -great detrimentito the spring, and a decided loss in its efficiency. .Bars of square or rectangular cross sectioinafter being coiled into helicalsprings, present broad, flatbearings coil-to-coil, and are not subject to this defect when driven solid, but have well known disadvantages which ,preclude their use. It IS .wellknown that inbars of circular cross section, when coiled into helical springs, the stress developed under load is lulllfOl'll'l at all points in the periphery, while in sections of square or rectangular shape even open to question.
Again, it is common practice in the manufacture of helical springs-to previously taper the cndsof the barsin order to produce end hearings in planes at right angles to the axis of the helix. A round bar when so tapered in the usual manner produces an end bearing face which decrea es in width toward the heel of the taper, until it runs out to zero. Such springs, when mounted for use under heavy loads, soon score and cut into the spring seats at the narrow part of the end bearing face, destroying the spring-seatsand the stability of the springs thereon, often times to such an extent'that unlooked for and complicated stresses are developed and the .life and efficiency of the equipment thereby curtailed.
By the present invention I have provided a spring which retains, to as great an extent as possible, the desirable features of the circular section, permits the use of a larger bar in a given solid length, provides a broad surface of contact coil-to-coil when the springs are driven solid, and a sufficiently wide end bearing near the'heel of the taper to prevent injury to the spring seat.
In the form shown, the spring developed takes the form of a bar which, in cross section (Fig. 5) has two opposite peripheral arcs and 21 of equal span connected by straight lines 22 and 23 of equal length. In the coiled spring, the straight faces 22 and 23 lie in planes at right angles to the axis of the helix in an axial section through the spring. In preferred form, the centers of curvature 2a of the arcuate faces 20 and 21 are in register. In other words, these curved faces form opposite arcs of a circle, while the straight faces 22 and 23 form opposite chords of equal length parallel to the diameter bi-secting the arcs. Each are 20, 21 is of approximately 120 degrees span, and each of the chords is of approximately ('30 degrees span. Or, putting it in another way, each of the chords 22 and 23 has a length substantially corresponding to the radius 25 of the arcs. Or, again, the length of the diameter bi-secting the chords is substantially 85% of the length of the diameter bi-secting the arcs.
The end bearing face 26 of the spring is formed by tapering the end of the bar from each flat face and toward the plane bi secting the curved faces, while the latter merge into flats as the taper progresses toward the end of the bar. The bearing thus afforded at the end of the bar is substantially equal to its greatest diameter, while at its narrowest point it has the full width of the fiat faces 22, 23.
By this construction of the spring the latter may be made from a materially heavier and thus stronger bar than it is possible to employ in the manufacture of the spring 27 of conventional circular bar type shown in Figs. 6, 7 and 8, having the same overall dimensions and a like play bet-ween the coils to afford suitable range and ease of action. It will be noted that the axial length of the two springs is substantially identical both in the open position (Figs. 1 and 6), and when the coils are driven solid under load (Figs. 3 and 8). It will be further noted that the bearing face 28 of the conventional spring has the ()bjECflOllfll'JlQ narrow heel 29 above referred to. which is destructive to the spring seat as distinguished from the broad heel 30 possessed by the present construction. A spring possessing markedly greater strength,
as well as causing less wear on the bearing seats is thus afforded.
Vhile the construction shown presents great advantages over prior constructions, the invention is not limited to the exact configurations shown, but is capable of embodiment in other forms without materially departing from what I claim as my invention. Y
I claim 1. A helical spring comprising a coiled bar which, when produced and in cross section, is bounded by two opposite arcs of substantially equal extent struck from an" approximately common center, and two substantially equal and parallel straight lines extending between the ends of the arcs, the flat faces of the bar lying substantially at right angles to the axis of the helix on an axial section through the spring.
2. A helical spring comprising a coiled bar which, when produced and in cross section, is bounded by two opposite arcs, each of approximately 120 degrees extent and struck from an approximately common center, and two substantially equal and parallel straight lines extending between the ends of the arcs, the fiat faces of the bar lying substantially at right angles to the axis of the helix on an axial section through the spring.
3. A helical .spring comprising a coiled bar having a pair of arcs formingapproximately two thirds of its cross sectional boundary, and a pair of opposite, substantially parallel straight lines between said arcs, the axial diameter of the bar between 7 said straight faces being less than the axial diameter between the arcs, and the straight faces of the bar lying substantially at right angles to the axis of the-helix in an axial. section through the spring 4. A helical spring comprising a coiled bar which, when produced and in cross section, is bounded by two opposite arcs of substantially equal extent struck from an approximately common center, and two substantially equal and parallel straight lines extending between the ends of the arcs, the flat faces of the bar lyingfsubstantially at right angles to the axis of the helix on an axial section through the spring, the ends of the bar being tapered to form end bearings for the spring, and the taper extending from the flat faces of the bar toward a plane bi-secting the arcuate faces.
In testnnony whereof I have signed my name to this specification.
ALAN N. LUKENs,