US1690471A - Splice bar - Google Patents

Description

Nov. e, 1928. 1,690,471

C. W. BREED SPLICE BAR Filed Feb. 2, 1928 Patented Nov. 6, 1928.

UNITED. STATES PATENT OFFICE.

SPLICE 313.

Application filed lebruary 2, 1928. Serial No. 251,254.

My invention relates generally to rail joints and more particularl to splice bars used in rail joints and to tie shaping and proportioning of such bars to obtain the maximum efficiency.

It is an object of my invention to provide a splice bar having such distribution of metal that the stresses in the outermost fibres above the horizontal neutral axis substantially 1 equal the stresses in the outermost fibres below said axis, and also that the stresses in the outermost fibres to the right of the vertical neutral axis substantially equal the stresses in the outermost fibres to the left of 1 said axis, and to obtain this distribution of stresses in a splice bar of unsymmetrical cross sectional area and adapted to fit a standard rail.

A further object is to provide a splice bar of unsymmetrical cross section in which the stresses in the extreme vertical and horizontal fibres are balanced and in which the minimum amount of metal is used, thereby to obtain a splice bar of maximum efficiency and hence greatest economy.

A further object is to provide an improved splice bar, as above specified, which does not extend beyond the base of the rail with which it is adapted to be used? V Other objects will appear from the following description, reference being had to the accompanying drawings, in which Figure 1 is a erspective view of the end portions of two a j acent rails joined by splice ars of my invention;

Fi e 2 is a vertical transverse section of a raifi' dint drawn to three-fourths scale; and

Figure 3 is a similar section, full size, of

the rail joint of my invention.

Splice bars, as used in rail joints, may be considered to be subjected to the stresses of a beam supported at both ends, for vertical loads and also for transverse horizontal I loads.

has some of the properties of the eificient I- beam section but which, at the same time, fills all the requirements of shape necessary or desirable in a splice bar.

In Figure 1 I have shown the ends of apair of adjacent rails 4, 6, joined by splice bars 8 and 10 by suitable bolts 12, in the customary manner. In Figure 2 I have shown the transverse section through the rail joint in which the shape of the section of the splice bars 8 and 10 is clearl illustrated and showing the surfaces of the ars which lie in contact with the rail. The rail joint is held in place upon the ties by the usual spikes 14 and the splice bars are drawn into firm wedging engagement between the head 16 and the base 18 of the rail by nuts 20 threaded on the bolts 12, a lock washer 22 being interposed between each of the nuts 20 and the splice bar 10.

' The rail illustrated is known as the 110- pound R. E. (American Railway Engineering Association).

As best illustrated in Figure 3, the splice bar section of my invention has a novel shape, the characteristics of which may best be described by the mathematical formulae which govern the conclusions that the present shape is the most economical and efiicient. In using these formulae the following letters will be used and may be defined as follows:

all)

X-X Horizontal neutral axis of the section Y-Y Vertical neutral axis of the section of an elemental area to the vertical neutral C Center of gravity (intersection of neutral axes) a? Distance from vertical neutral axis to outermost fibre of right-hand portion of the section w Distance from vertical neutral axis to outermost fibre of left-hand portion of the section 3 Distance from the horizontal neutral axis to the outermost fibre of upper portion of the section R 3 Distance from the horizontal neutral axis to the outermost fibre of lower portion of the section A Total area of section AA Elemental area p a Distance from the center of gravity of an elemental area to the horizontal neutral axis t Distance from the center of gravity axis 7 M Static moment T Moment of inertia about horizontal neutral axis I Moment of inertia about vertical neutral axis S S Section modulus of right and left portions, respectively, about the vertical neutral axis S S horizontal neutral axis As'fa r as feasible, the above letters have been applied as reference characters in Figure 3 of the drawings.

Section modulus of upper and'lower portions of section with reference to the The static moment of an elementary area and the total area about the neutral axis may be represented by the formulae:

Mxx 'UIAA 0r, M MA or, M EvAA fvdA and:

'y 2: or y 73 at fvAdA The moment of inertia of a section may be defined as the summation of the products of the elementary areas of a section by the squares of their distances from the center of gravity of the section, being expressed in inches to the fourth power, the formula being:

I fggzu m fmdA where the moment of the section is taken about an axis parallel to the XX axis and at a distance y therefrom.

The section modulus is the quotient of the.

moment of inertia divided by the distance from the neutral axis to the outermost fibre. In an unsymmetrical section there may be two section moduli, the least being the determining factor in finding the resisting moment. In the splice bar section of my invention the section modulus of the portion above the horizontal neutral. axis is substantially equal to the section modulus of the portion below said axis. In a similar manner the section moduli of the portion to the right and tially equal.

When this condition prevails, the splice bar will be of the most economical shape, since the stresses in the upper and lower outermost fibres will be equal and the stresses in the outermost right and left fibres will also be substantially equal Whenever the bar is subjected to strains of a beam.

Of course, these conditions are present in I-beams of usual section, but my invention lies particularly in the provision of a splice bar of unsymmetrical section which has the properties of such a standard I-beam and which is so shaped as to be ada ted to contact with the rail beneath its head ange and upon the base flange over substantial areas.

The splice bar section disclosed in the drawings has these desirable properties in that the section moduli of the upper and lower portions are substantially equal and the section moduli of the portions to the right be illustrated by the following tabulations and left of the vertical neutral axis are subof the properties of the section shown in the 5 stantially equal. These propertiesmay best Area of section is 5.194 inches 2 Distance y is 2.2143 inches Distance 3 is 2.2159 inches Distance 00 is 1.1529 inches Distance :0 is 1.1596 inches Moment of inertia about horizontal drawings neutral axis, I is 9.585 inches Moment of inertia about vertical neutral axis, I is 1.494 inches Section modulus, S is 1.29 inches Section modulus, S is 1.288 inches Section modulus, Sy. is 4.32 inches 8 Section modulus, S is 4.33 inches 8 From the above data it will be seen that in the splice bar section of my invention the section moduli are nearly equal for corresponding coordinates and that the differences are so small, when compared to production tolerances, as to be negligible. The above dimensions and properties are, of course, merely illustrative and will be different for splice bars designed for use with rails of different weight.

Within practical limits the above described splice bar section is the most economical possible for a given weight of material and for an unsymmetrical shape suited for engagement with the side of a rail. It will be noted that the outer edge of the lower portionof the splice bar lies practically coincident with the plane assing through the edge of the rail base ange, thus making it possible to spike the splice bar to the ties.

While I have shown and disclosed a particular embodiment of my invention, it will be apparent to those skilled in the art that slight variations may be made without departure from the principles of my invention. I, therefore, desire the sec e to be limited only by the claims which fol ow.

I claim:

1. An unsymmetrical splice bar having the portions above and below the horizontal neutral axis of substantially equal section modulus and the portions to the right and left of the vertical neutral axis of substantially equal section modulus.

2. An unsymmetrical splice bar in which, when the bar is subjected to a strain, the stresses in the extreme upper and lower fibres are substantially equal, and the stresses in the extreme right and left hand fibres are also substantially equal.

3. An unsymmetrical splice bar having intersecting neutral axes, in which the section modulus on one sideof each of said neutral axes is equal to the section modulus on the other side of each of said neutral axes, and which is adapted to lie wholly within verti cal planes passing through the edges of the base of the rail.

4. A splice bar of unsymmetrical section and having substantial areas adapted to contact With the base flange and head of a rail, in which the section moduli of the portions of the section to the right and left of the vertical neutral axis are substantially equal,

, and which is adapted to lie within vertical planes passing through the edges of the base of the rail.

5. An unsymmetrical splice bar adapted to lie entirely within vertical planes projected to the edges of the base flange of a rail, in which the section moduli above and below the horizontal neutral axis are substantially equal and the section moduli to the left and right of the vertical neutral axis are substantially equal.

6. An unsymmetrical splice bar adapted to have substantial areas of contact with the base flange andhead of a rail, in which the section moduli above and below the horizontal neutral axis are substantially equal and the section moduli to the right and left of the vertical neutral axis are substantially equal.

In witness whereof, I hereunto subscribe my name this 27th da of January 1928.

CHA LES W. BhEED.

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