US1972857A - Leaf spring - Google Patents

Description

sep1.11,1934. 1 G EUCH 1,972,857

LEAF SPRING v Filed Feb. 1v. 19:52 v 2 .sheets-sheet 1 v 'Q4'. @1- f Patented Sept. 1934 LEAFSPRINGv Glenn F. Couch, Rochester, Y., ,assignonto The Symington Company, corporation of Marylandl ,y

New York, N. Y., a

v Application February 17, 1932,'seria1 No. 593,633

* claims. (c1. 267-55) This invention relates to leaf springs and, more particularly, to elliptic springs especially adapted for supporting a railway lvehicle bolster i fro associated side frames.

5- The principal object of my invention, generally considered, is the provision of leaf or elliptic` springs in which the effective span of the leaves is varied as the amplitude changes to avoid har-4 monic vibrations.

'l0 Another object of my invention is to provide a leaf or elliptic spring in which the ultimate capacity is gradually built up instead of being kept on a low plane, and then suddenly shot up to the ultimate capacity near the end of the compres-f lsion. Y A further object of my invention is the provision of a'leaf or elliptic spring inwhich Athe effective span is decreased as the amplitude'of compression or leaf deflection is increased, whereby resonance is avoided. A

A still further object of my invention is .to provide a leaf or elliptic spring in lwhich the period of vibration is varied or decreased as the amplitude is varied or increased, to thereby avoid a cumulative increase in'amplitude of vibration due to synchronous energizingforc-es. f-

Other objects and advantages of the invention relating to the particular arrangement and con- 3o ent as the description proceeds.

vention f .l

Figure 1 is a fragmentary elevationall viewrofl an elliptic spring embodying my invention, the

section, and the leaves being shown in free position in full lines with the inner leaves shown in flexed position in dotdash lines.

Figure 2 is an end elevation of theend blockA n t Y, I necessary weight, while st1l1 Amaintaining the reqshown in Figure 1, on an enlarged scale.

Figure 3 is a sectional'view of the end block on the line 3--3 of Fig. 2 looking in the direction ofthe arrows,.illustrating the progressive -movement of the line of contact between the uppery engaging spring plate and 'the corresponding bearing surface on said block.

Figure 4 is a bottom plan rof :the blockl shownV in Figures 2 and 3.

Figures 5, 6, 7 and 8 are views corresponding,-

illustrated in Figures 1 to 4, inclusive, an elliptic struction of the various parts will become appar-' l o A f v end-.webrl of the block 8 is desirably formed with Referring to the drawings 4-illustratinY vmyinl. I

1 i 1 wardly to provide a` badge plate area readily Visspring bands and one end block being shownin spring 1 is fragmentarilyV shown, which spring may be utilized for the resilient support of any desired object, but is particularly adapted for the support of a railway vehicle bolster from an associated sideframe. The spring 1 comprises a plurality of leaves or plates 2 of varying lengths providing the familiar stepped construction for each group or bank 3 of leaves. The center portions of said groups-3 are held together by bands 4, the outer portions 5, that is, the upper portion of the upper band and the lower portion of the lower band being preferably increased longitudinally of the leaves 2 to provide an enlarged supporting area 6, the full extent of which gradually comes into engagement with the outer surface 7 of the engaged plate v2,l whereby the effective span of the spring .leaves is gradually decreased as *thev spring is compressed. "This action is supplemented, in the present instance, by the novel form of the end blocks `8, only one of'whic'h is illustrated. Each end block comprises a pair' of side portions I9 joined'by an outerend web 10 and a body portion 11 preferably cored,'as indicated at 12, to minimize weight. The end web 10 and the body portion 11 are desirably spaced, as shown most clearly in Figures 3 and 4,

an outer :surface 15,sloping downwardly and out-` ible .when the spring is used in a position below the normal eyelevel, as, for example,4 when it is usedrin a railwaytruck'forsupporting an associatedbolster. The inner surface lis desirably sloped at its lower portion to correspond with the slope of the outerfsur'fa'cel 15 and cut away intermediate its junctions with'thesides 9 to avoid'unuisite strength. y l

The body portionll of each lend block 8 has upper, and lowerI lspring bearing surfaces 17 formed on vsuch a curvature that the effective line ofcontactloetween,thespring leaves 14 and said surfaces .gradual1y moves inwardly as the elliptic spring is-AA compressed or flexed, the construction` desirablyfb'eing such that the rate ofinward movementapproximates the rate of springlde-y ilection,l whereby the curve representing the f springstress, as compared with the amount of spring compression, gradually increases in steepness as thespring is compressed without any sharpv increase, near the point'where the spring goes solid.

` form of end block with conventional spring bands,

lno

Q with the end blocks 8 of the first embodiment, and

G05 embodiment, except that the inner surface 16a is in the preceding embodiment,

The dot-dash lines radiating from the V uppers surface or bearing area 17 of the end block 8 represent successive positions of the lower spring plate 14 of the upper spring group, the circles 20',

21, 22, 23 and 24 indicating positions of tangency between the spring leaf 14 when in positions 25,

26, 27, 28 and 29, respectively. It will, therefore,

be seen that as the spring leaf 14 and, of' course, the other associated leaves deflect from the position 25 to the position 29, the span is progressively shortened the distance represented by the difference in positions betweenv the places of tangency 20 and 24.

Although, in the present instance, the spring bands and end blocks are constructed so that they assist one another in providing increased stiffness for the spring as the spring is compressed, it will be understood, that I may use my novel or my spring bands with conventional end blocks, While still securing, in a measure, the desired result.

Referring now to the embodiment of my invention illustrated in Figures 5 to 8, inclusive,van

elliptic spring 1@ is there shown which corresponds substantially with the spring 1 of the rst embodimen't, except that the spring bands 48L are of conventional construction, such as may be used the end blocks 8a have spring bearing surfaces 17a curved differently from the surfaces 17, but so constructed that the desired result is attained as In the present embodiment, the bearing surfaces 17a on the spring blocks 8a are curved about the relatively short radius ISaat .their outer portions and about vthe relativelyrlong'radius19?L fory ,A the major portions of the area toward the inner sides thereof, thereby accomplishing a result similar to that accomplished by the end blocks ofthe first embodiment, except, of course, providing a force-absorption curve of somewhat different characteristics because of the difference in cur- `vature of' the bearing surfaces which thereby cause the position of tangency to travel across the bearing area in a slightly different manner. `The end'blocks 8a may be constructed otherwise substantially as the endV blocks 8 of the preceding not shown inclined vlike the outer surface. It will be understood that, if desired, I may use bands for the spring of the present embodiment corresponding with the' bands 4 ofthe preceding embodiment. Except as specifically described in connection with the present embodiment, thev same may correspond with the precedingfembodiment.-

From the foregoing disclosure, it Will-be's'een that I have devised a'leaf spring `which, vin theV` embodiments disclosed, is generally designated as an elliptic spring, especially adapted for the support of a railway vehicle bolster. By vvconstructing the bands and/or the `end blocks "so e that the effective length of the spring varies, preferably inversely with the amplitude of vibration or deflection, resonance or cumulative increase in amplitude of deflection from synchronism, or vibrating forces acting periodically in synchronisrn with the natural vibration period of the spring, is avoided. In other words, by providing that any change in amplitude immediately alters the span'or free length of thegspring, we have an automatically self-correcting 'device in that excessive amplitude alters the spring vibration period, so that what otherwise might be synchro- Vnous impulses do not act cumulatively to increase the'amplitude of spring vibration.

AlthoughUI have: disclosed certain preferred embodimentsof my; invention, it will be understoodgtha't modifications may be made within the spirit and scope ofthe appended claims. l I.claim:--- v 1. A leaf lspring comprising a plurality of spaced .end blocks and a spring leaf spanning the distance between them, each of said blocks `having a` curved bearing surface engaging saidl'eaf, the Acurvature of each bearing surface being decreased as it approaches the other block. 1

v2. An elliptic spring comprising a plurality.. of spaced end blocks and a set of spring leaves above and below said blocks andspanning the distance therebetween, eachset comprising leaves' ofv different lengths, the lengths of said leaves increasing to a maximum fromV the outer to the innermost leaves of said sets, each-of said blockshaving curvedbearing surfaces vengaging said'innermost leaves, the endsof; said innermost leaves only extending toward one another over the outer edges of said bearing surfaces, the curvature of saidvbearing surfaces being sharper adjacent the outer ends of the blocks than adjacent-the inner ends thereof. v

3. A leaf springcomprising a plurality-of spaced end blocks, a set of spring leaves spanning the distance between said blocks, and a center band encircling said leaves, each of said blocks having a curved bearing surface engaging a leaf, the curvaturel ofthe bearing surface of each block: beingV sharper adjacent the outer end ofthe vbloclrthan adjacent the inner end thereof, that portion of said band engaging the outermost spring.- leaf vbeing` extended, longitudinally -of said leaf, beyond the-normal contacting area therewith, so that upon flexing of the `spring la greater than normal amount of supporting arear is gradually presented to said leaf to thereby provide] for a decrease in the effective span. 1

f 4. An end bearing block for .leaf springs comprising side membersl joined byfa `body portion presenting curved bearing surfaces .forengagement with leaf springs, the curvature of said bearing surfaces being sharper adjacent the outer end ofV said block than adjacent the inner'end thereof.

5. A leaf spring comprising apair of spaced end blocks, each ofv said blocks'having curvedv upper-.and lower bearingsurfaces, the :radii of curvature Aof vthe surfaces` of each block :being relatively small at the outer `ends away from theffttD lower surfaces, so that as the spring yfisflexed` the f lines of engagement with the blocks travel from the portions of the bearing surfaces of relativelyv small radii to' those of'increasedradii. d

GLENN-ECOUCH.

Images