US993208A - Spring. - Google Patents

Description

G. WATSON & R. A. S. PAGET.

} SPRING. APPLICATION FILED JAN. 9, 1911.

Patented May 23, 1911.

Fig.4.

INVEN TORS UNITED STATES PATENT OFFICE.

CECIL WATSON AND RICHARD ARTHUR SURTEES PAGET, OF LONDON, ENGLAND.

SPRING.

Specification of Letters Patent.

Application filed January 9, 1911.

Patented May 23, 1911.

Serial No. 601,728.

To all whom it may concern:

Be it known that we, CECIL IVA'rsoN, associate member of the Institute of Civil Engineers, and RICHARD ARTHUR Sonrnus PAGET, baronet, both subjects of His Majesty the King of Great Britain, and residents of London, England, have invented a certain new and useful Improvement in Springs, of whichthe following is a specification.

This invention relates to improvements in coiled helical springs for railway buffing and draw gear and other purposes in which springs are subjected to varying compressional stresses, and in particular to stresses sufiicient to bring the coils in contact with one another, and has for its object the prevention of the relative rotation of the extremities which normally occurs during the compression and natural extension of coil springs; compression tending to rotate the extremities of the spring in one direction and extension in the opposite direction. In the case of buffing and draw springs of railway and other rolling stock, this action has an injurious effect subjecting the bufling and draw gear to constant torsional strains which cause wear and tear, and tends to twist the bufler head and draw hook. Any mechanical device for resisting rotation necessarily subjects the spring to distortion. The use of pairs or nests of concentric right and left hand springs does not avoid the difliculty, for each individual spring tends to rotate and is therefore subject to strain if rotation is prevented, or causes wear on the ends of the springs and the surfaces against which they abut if rotation is permitted, while the unequal size of the concentric springs makes it practically impossible for them to have equal rotation.

In the accompanying drawings :Figure 1 represents a ortion of an ordinary bar from which it 1s desired to form a helical spring according to this invention; Fig. 2 shows said bar bent on itself; Fig. 3 shows how said bar may be hammered out so as to present an even surface corresponding to the angle between the right and left hand coils to be made; Fi 4 is a similar view to Fig. 1, except that t e bar is shown thickened at the bendin point as shown by Fig. 5, which permits a onger point to be forged out as shown in Fig. 6; and Fig. 7 represents a coiled spring formed from V bars as shown in Fig. 3 or 6.

According to this invention, each complete spring is composed of two inverse and preferably equal and opposite co-axial coils, A and B as shown in Fig. 7 so shaped at their inner ends 0 as to form in effect a single right and left hand coil of which the rotation of one half A practically neutraL izes the rotation of the other, 13 so that the relative rotation at the outer ends is m'l. Springs according to this invention, t. 0. free from liability to twist and capable of resisting stress in excess of their working capacity. may be made for example by coiling a V-shaped bar, as for example a straight bar as shown in Fig. 1 turned back on itself at the center as shown in Fig. 2 and shaped as hereafter described around a mandrel.

The V-shaped bar is so formed with a wedge-shaped end as shown in Figs. 3 and 6 that after being coiled into a right and left hand spring the coils when compressed home bear evenly on one another in true alinement and the end faces of the spring are in planes at right angles to the center line of the spring, the conditions being similar to those of two separate oppositely coiled springs with their inner bases coinciding. For this purpose the angle D of the V-shaped bar and of its wedge-shaped end F must be so formed that when, after coiling, the two members G and H of the V are compressed together so as to be in contact from the point of bifurcation to the point at which the outer surfaces of the wedge-shaped end would, if prolonged, meet at a point, the outer surfaces form similar helical curves of pitch equal to that of the right and left hand helices A and B. For instance assume the angle of the helix of the right and left hand coils to be 5 when compressed home then the wedge shaped end is tapered out to roughly correspond with this angle so that when the whole spring is compressed home all the coils bed fairly on one another.

In the ideal arrangement the helices are at their full section up to the point of bifurcation, the V-shaped bar being initially thickened as shown at I, Figs. 4 and 5 at the center and then bent into V form, the thickened portion being forged out into a wedgeshaped end with helical surfaces as above described. We have found, however, that for practical purposes it is feasible to form the V from a bar without initial thickening in the center, the bar in this case being bent and formed into a V with helical surfaces and wedge-shaped end as above described by tapering the coils as shown in Figs. 3 and 6 toward the point of bifurcation so that a portion of the wedge is as it were bisected along a plane transverse to the aXis of the helices so as to form separate coils tapering in depth toward the end of the wedge and having their inner surfaces in contact even when the spring is uncompressed. Experiment has proved that such tapering though it weakens the spring in respect to its resistance to lateral strain in no way weakens it in respect to its resistance to compression or even to the strains set up when the coils are compressed home while the omission of the initial thickening materially reduces the cost of manufacture.

It has heretofore been proposed to use double volute springs made in one piece with the coils of one half of the spring inclined in an opposite direction to that of the other half, though not for the purpose described in this specification as with such volute springs the point where they join takes no part of the direct thrust when compressed. It has also been proposed to employ separate oppositely coiled helical springs for the purpose of neutralizing rotation but this proposal necessitates the introduction of means for coupling same and does not obviate the possibility of two rightor two left hand springs being erroneously coupled while the essence of this invention is the combination in a single spring of two equal and inverse helical coils whose inner ends merge into a single wedge-shaped end of double helical form as described.

The wedgeshaped end may be truncated if desired so as to reduce the amount of drawing out, provided that the wedge portion be of sufficient length to give adequate support to the adjacent coils when compressed home.

lVhat we claim is:

A right and left hand spring for resisting compression and preventing end rotation, having two equal and opposite co-aXial helices in the same planes and terminating at their inner extremities in a single wedge shaped end of helical form and in plane with the helices.

In testimony whereof we have hereunto set our hands in the presence of two subscribing witnesses.

CECIL WATSON. RICHARD ARTHUR SURTEES PAGET.

Witnesses E. THOMPSON, W. W. JoNEs.

Copies 'of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C.

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