US2519169A - Railway truck - Google Patents

Description

Aug. 15, 1950 P. K. BEEMER ET AL RAILWAY TRUCK 4 Sheets-Sheet 1 Filed May 30, 1945 m- R m SN SN 5 mm SN M E Q v s n w s l|.|l|ll I- Y 3N mm R R L E m mm m .V mu m n w B L M mu .ov i l.. K B 2 l m J mm m mm 2% 3 3 mm ow 0N Q I N GE 3 53w 6d 8 Nm 3 6 win Sn 3 m 8 3 IF m J.

15, 1950 P. K. BEEMER ET AL ,51

RAILWAY TRUCK Filed May 30, 1945 FIG. 3. 63 so 4 Sheets-Sheet 2 INVENTORS PAUL K. BEEMER FRANCIS L. CARLISLE AM/9M ATTORNEYS Aug. 15, 1950 P. K. BEEMER El AL RAILWAY TRUCK 4 Sheets-Sheet 3 Filed May 50, 1945 FIG. A.

FIG. 5.

I a I I I I I I I I I l I. I a. n

43 40a 40 40 43 408x 40b 40c FIG. 4.

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INVENTORS PAUL K. BEEMER 9o FRANCIS CARLISLE WWW/M1 ATTORNEYS Aug. 15, 1950 P. K. BEEMER ETAL RAILWAY TRUCK 4 Sheets-Sheet 4 Filed May 30, 1945 FIG / 60d 35d 35 22 INVENTORS PAUL K. BEEMER FRANCIS L. CARL|SL E ATTORNEYS Patented Aug. 15, 1950 RAILWAY TRUCK Paul K. Becmer, Inglewood, and Francis L. Carlisle, Pasadena, Calii'., assignors to Preco Incorporated, Los Angeles, Calii'., a corporation of California Application May 30, 1945, Serial No. 596,684 Claims. (01. 105-193) This inventionhas to do with structure and design of trucks for railway cars, the general purpose being to provide a truck of simple des n and structure, capable of ready substitution for existing trucks, and adapted to permit higher safe speeds of operation than are permitted by trucks now in use.

Although the use of the invention is not limited to freight cars, our new truck has been designed with that use particularly in view, and so the invention will be here described with a view to that use, but without any implied limitation to it. As applied to freight cars the primary utility of the invention lies in its ability to allow freight car operation, under existing limitations, at substantially higher speeds than those which are considered safe today with existing truck equipment.

This invention involves several distinctive features which will be most fully understood from the following detailed descriptions of specific and preferred forms which illustratively embody the invention. One major characteristic of our improved truck structure is its embodiment and provision of a full floating suspension of the car body, or, more specifically, of the truck bolster which carries the body. This suspension is provided in such manner that, aside from desirable snubbing or damping, all movements of the car body or bolster with relation to the truck (movements vertically, laterally and longitudinally) are purely spring-opposed. The suspension springs take all of the thrusts in all directions; there are not guiding or similar restraints which involve frictional sliding motions. That is, the body or body-carrying bolster is not guided or normally limited in any direction other than by the suspension springs, excepting for the snubbing or damping actions; and there are no frictional resistances in parallel 'with the spring actions. Among other things, this type of spring suspension not only provides for softer connection of the car body with the truck frame and thus allows f higher safe speeds, but also provides a structure which is almost entirely free of frictional wear and whichtherefore has longer operative life than present trucks.

It is also a feature of the invention that all of the movement thrusts are taken by a single set of springs. While a plurality of individual springs is employed in the set, each spring in the set acts to allow spring opposed movements in all directions and takes corresponding thrusts in all directions. In their preferred forms, these springs are coil springs which take the vertical load thrust axially and are designed to be relatively soft under the vertical load but relatively stiff and rigid in all transverse directions so that they oppose a relatively stiff restraint to both the lateral and longitudinal relative movements of the car body or the bolster. As will appear, I

in one form of our invention we prefer to somewhat modify the spring action in the lateral plane,

snubbing or damping action is applied to both the vertical and the lateral oscillations, preferably with a single set f snubbers which act both vertically and laterally. And, as will appear, the snubbing or damping arrangement is such as to cause the car body or bolster to have a swinging motion rather than a rolling motion WithreIation t the truck frame. The tendency to roll is damped. All of these damping actions are preferably performed by a single set of canted snubbers which, by virtue of their oblique lines of action, act both vertically and laterally.

The provision f a freely floating bolster, with all of the relative movements fully accommodated between the bolster and the truck frame, en-

ables us to make the truck frame itself rigid, as it is not called upon at all to accommodate any relative movements. That rigidity of truck-framing is desirable, as it eliminates any relatively moving and frictionally wearing parts and provides accurate rectangular alignment oi the frame assembly. And at the same time we make provision for easy and quick disassembly of the truck frame by the simple operation of lifting the spring plank from the two side frames.

All of these features, and others, together with corresponding accomplishments, will .be most fully understood from the following detailed descriptions of the preferredembodiments shown in the accompanying drawings in which:

Fig. 1 is a transverse vertical section showing one form of our improved truck;

Fig. 2 is a sideelevation and, Fig. 3 is a plan of the same at a. reduced scale;

Fig. 4 is a detail horizontal section taken on line 4-4 of Fig. 2; v

Fig. 5 is an enlarged detail section taken on line -55 of Fig. 1;

Fig. 5a is a horizontal section on line 50-51! of Figs. 1 and 5.

Fig. 6 is an enlarged detailed section taken as indicated by line 6-6 on Fig. 3, showing one preferred form of snubber which may be used in our" invention;

Fig. 7 is a fragmentary sectional enlargement of certain portions of Flg. 6;

Fig. 8 is a fragmentary section, similar in aspect to that of Fig. l, and showing a modification;

Fig. 9 is a fragmentary plan and Fig. 10 is a fragmentary side elevation, showing a modification; and

Fig. 11 is a section taken as indicated by line llll on Fig. 8.

Figs. 1 to 4 illustrate general organization of one preferred form of the truck. There the two wheel-and-axle units 22 and their association with the side frames 22, and the particular design of the side frames, are of no special import in our invention, except that the side frames are designed, in some particulars, to cooperate with other elements of our invention. The side frames may be directly carried by the axle journals 2|, or springs may be interposed if desired.

The two side frames 22 form the lateral elements of the truck frame, of which the laterally extending spring plank 25 forms the transverse interconnecting element. Side frames 22 are formed with central openings 26 to accommodate several parts as hereinafter described. At the lower part of opening 26 each side frame is formedwith a wide spring plank platform 21, the shape of which in plan is best shown in Fig. 4. Rib formations 26a, which surround the central frame openings 26, extend out to the outer edges of the platforms to stiffen them. The approximate outlines of one pair of these ribs is shown in dotted lines at the right side of Fig. 1. The upper faces of these platforms 21 form broad surfaces upon which the two end portions 25a of spring plank 25 rest. These end portions 25a of the spring plank are of approximately the same plan dimensions as platforms 21 (see for instance Figs. 1, 2 and and the under faces of end portions 25a are centrally relieved, as shown at 28 in the sections of Figs. 1 and 5 so as to form a circumferential bearing surface which bears upon the circumferential portions of platform 21. The general configuration of this circumferential bearing faceis shown at 29 in dotted lines in Figs. 3 and 4. The purpose of forming the bearing face in such a manner is to concentrate the area of that bearing face at the greatest practicable radius from the vertical central axis A of each side frame 22, and thus to gain as much rigidity as possible from the frictional interfacial contacts of the spring plank and side frames.

The spring plank is positively and rigidly connected with each side frame by four vertical dowel pins 30 which are accurately fitted to both elements to hold them in rigid relationship, and are also located at maximum radii from the central vertical axis of the frame. The spring plank being joined to the side frames in such manner as described, and the spring plank being uniformly wide from end to end, the whole assembled truck frame is exceptionally rigid in a horizontal plane. At the same time the frame may be easily disassembled by lifting the spring plank with the dowel pins from the side frames. Fig. 3 shows the general plan of the spring plank, bounded at its longitudinal edges by the longitudinal upstanding flanges 25b.

The truck bolster, designated generally by the numeral 35 extends in a lateral direction across the truck frame, lies over the spring plank 25, and is substantially co-extensive in length with the spring plank. At its center it has the usual swivel arrangements 36 for carrying car bolster 21, indicated in dot-dash lines in Fig. 1. We

contemplate no changes in the relation and connection of the car bolster to the truck bolster. and our improved truck as a unit may be substituted for present trucks without making any other changes.

The details of structure and design of truck bolster 35 need no particular attention except insofar as the bolster is designed to take and be supported by the set of suspension springs. Ateach outer end, over the outer end portions 25a of spring plank 25, the bolster is formed with downwardly depending flanges 35a and 35b which form inverted circular cup-shaped recesses to take the upper ends of the several suspension springs. The complete spring set is composed of two spring units, one spring unit at each end of the bolster for the purpose of resiliently and independently supporting each of the two ends of the bolster upon the two opposite side frames. In general, each of these spring units may be composed of one or any suitable number of individual springs.

In the design shown in the figures now under discussion, each spring unit is composed of two nests of springs, each nest composed of a plurality, here shown as three, concentric coil springs. Thus the drawings show a spring unit at each end of the bolster composed of two nests of springs 40, with the two nests arranged on the central lateral axis of the bolster and of the spring plank. The two spring nests 40 composing each spring unit are seated on a spring seat plate 4|, and these two spring seat plates 3| are supported upon the end portions 25a of the spring plank directly above the supporting platforms 21 of the side frames. In fact, as will be seen from an inspection of Fig. 1, the arrangements of the spring unit 40, spring seat 4| and frame platform 21 are symmetrical about the vertical central axis A of the side frame in a transverse plane; and from Figs. 2 and 3 it will be seen that the same is true in a longitudinal plane. The spring supported bolster projects its ends through side frame openings 26, with adequate vertical clearance between the top of the bolster and the upper boundary of the frame opening (see Figs. 1 and 3) and also with adequate clearance for free fore-and-aft movement of the bolster (see Figs. 2 and 3). The bolster is thus unconfined by the frame with regard to its move- .ments both vertically and longitudinally with reference to the frame, and also with regard to movements laterally with reference to the frame. All of those relative movements of the bolster are primarily opposed, and the resulting thrusts taken, by the springs alone. The frame neither guides nor normally limits the movement of the bolster in any direction.

Throughout this description we are using the term "longitudina1ly as meanin longitudinally with relation to the truck frame; and consonantly the term laterally is used to denote a direction across the truck frame-the length directions of the lateral bolster and spring plank.

Figs. 1 and 2 show the bolster at approximately the level it assumes when carrying an empty car body; the dotted line indications at 35L in Fig. 1 indicate the typical level to which the bolster will lower under full car loading. The vertical clearance of the side frames above the bolster is designed to be large enough to freely allow maximum bolster oscillation in a vertical direction under all loading conditions, without the bolster contacting the frame. The longitudinal clearance shown in Fig. 2 is designed to be suficient to allow maximum longitudinal oscillation of the truck frame with reference to the bolster and car body, without the bolster contacting the frame. And there are no stops or other positive limitations to relative lateral movement of the bolster under normal service conditions. The stops shown at I! in Figs. 2 and 3 allow lateral movements somewhat larger than the maximum movement allowed in normal service by the bolster supporting springs or springs and rollerv unit, and only engage the side frames under abnormal circumstances (e. g. derailment).

In the particular design and arrangement shown in Figs. 1-5, spring seats ll have upwardly projecting circular peripheral flanges lla surrounding the lower ends of the nests. As is best seen in Fig. l and in the enlarged sections of Figs. 5 and 5a, the outermost large coil spring 40a of each spring nest has its upper end confined by flanges 35a, 35b of the bolster and its lower end confined by flange a of the spring seat. Inside the outer spring 40a .at each end, there is an annular channel or troughshaped seat, 43, these seats taking the ends of intermediate spring 40b, and serve to space all three springs in a spaced concentric group. The inner small spring 400, like the large spring Illa, can bear directly on spring seat II and on bolster 35.

The two spring units of the truck may be seated at their lower ends directly on end portions 25a of the spring planki that is, the spring seat plates 4| might be directly seated upon or formed as parts of the spring plank portions 25a. Fig. 8 shows a simplified design in which the springs seat directly on the spring plank. But in the form of Fig. 1 we prefer, in order to introduce a modification in the lateral action of the spring units, to mount spring seats 4| on the spring plank through the medium of a mounting means which introduces a relative lateral movement having certain inherent characteristics under load, as hereinafter explained. As shown in the drawings, spring seats 4| are formed on their under faces with roller seats 50, and the upper faces of spring plank portions 25a are formed with similar opposed seats 5|. The opposed seats take rollers 52 between them, the axes of the rollers being in a horizontal plane and at right angles to the lateral axes of the spring plank and bolster. In a vertical lateral plane, such as that of Fig, 1, the opposed roller seats are concavely curved on radii greater than that of the rollers. Preferred details of the seat shape will be discussed later.

Fig. 8 is a fragmentary sectional view similar to the left hand end of Fig. 1, but showing the springs seated directly on the outer end portions of spring plank -25d. In this figure the spring plank is shown as having a raised spring seat portion lid on which the spring seat directly instead of on the special spring seat ll of Fig. 1. Other than this diiference and the elimination of rollers 52, the form of Fig. 8 is like that of Fig. 1. This structure of Fig. 8 has relative advantages of simplicity, weight saving and low cost. Its action, as will be later explained, is somewhat different from that of Fig. 1. as re- Bards lateral movements.

Two canted snubbers or dampers are utilized, acting upon the opposite ends of the bolster and arranged symmetrically with relation to the vertical central axis of the bolster and the truck. In the design shown in the figures at present under discussion the two snubbers fill are arranged on axe S which (see Fig. 3) lie in vertical lateral planes equally and oppositely spaced from the central lateral axial plane 01' the bolster, and (see Fig. 1 are inclined upwardly and inwardly. The angle of inclination may be varied; it is shown in these figures as being about 45. The upper ends of these snubbers are connected universally at points 6! to the side frames. See Fig. 1 for the location of those connecting points. The lower ends of the snubbers are universally connected to the holster at points 52, the location of which is indicated diagrammatically for the snubber at the right-hand side of Fig. l. The lower connection of the left-hand snubber in Fig. 1 is at a corresponding point but, for clarity of the drawings, is not indicated in Fig. l but is shown in Fig. 6.

The lower connection of each snubber is to a bracket G3 which is secured to and depends from the end of bolster 35 at one side; see Figs. 2 and 3. Fig. 6 shows the lower end 53a of bracket 63, and the lower oint of universal connection, which has been desi nated 62. may be taken as the center of the universally swivelling joint which is formed by 63a and the lower end formation 64 of the snubber mechanism. The interior surface of 64 and the bracket end 63a are both spheric, to allow of the limited universal movement necessary at that point, At its upper end each snubber has a universally swivelling joint which comprises a ball 65, seated in or against a spheric socket 66 in the side frame. A pin 61, fitting loosely enough through a hole 61a in ball 65 to allow the limited necessary universal movement, may be utilized to prevent accidental separation of the two parts. Connection point 6!, previously referred to, may be taken to be the center of ball 65.

Generally speaking, the action of each snubber is to resist either upward movement or inward lateral movement of the bolster end to which it is connected. Each snubber acts along its inclined axis S to resist axial compression of itself. And thus, with the upper end of each snubber connected with the truck frame, and the lower end connected with the bolster, the action of each snubber is to resist any movement of its end of the bolster which has a component upwardly and inwardly along the axis of the snubber. The relative inclination angles at which the snubbers are set will depend upon the proportionate amount of damping action desired to be applied respectively to upward vertical movement of the bolster and inward horizontal movement ofthe bolster. The inclination angles shown in Fig. l are typical.

Any suitable snubber having a suitable damping action may be utilized. Figs. 6 and 'I show one simple type of structure. Fig. '7 is a fragmentary enlargement of portions of Fig. 6, but showing the snubber in its position of full compression. A plunger 10, reciprocating in an inner cylinder 1 l, is permanently connected at its outer end to the head 55 which is attached to the truck frame. An outer cylindric wall 12 concentrically and spacedly surrounds the inner cylinder wall, to form an oil reservoir I3 between the two. The cylinder wall and outer wall 12 are preferably formed as an integral casting, and the lower connector head 64 of the snubber is formed integrally in the same casting. The outer wall 12 near its upper end has a spring seat shoulder I4, seating a coil spring 15 which presses at its opposite end against head flange 65a and thus tends at all times to expand the snubber in length and to move plunger out of cylinder 1|. The strength of the spring is intended to be only sufflcient to keep ball 65 against its seat 66. The spring does not play any substantial part in the action of the snubber. A cover sleeve 18 is attached at one end to head flange 65a and surrounds outer wall 12. A wiper or oil seal is provided at I1, and a dust wiper is also provided at 18 at the end of cover sleeve 19. A combined oil wiper and packing gland is provided at 80 in an annular plug member 8| which closes the otherwise open annular space between cylinder wall II and reservoir wall 12.

Two valvular means are provided for controlling the amount and the character of damping action exerted by the snubbers. At the end of cylinder II a passage 85 leads into a transverse bore 86 from which a small transverse orifice 81 leads into reservoir I3. This orifice is controlled by an adjustable needle valve 88 and provides an orifice which, although adjustable, is an orifice of fixed size in the operation of the snubber. The snubbing or damping action due to the flow of liquid through this fixed orifice is therefore approximately proportionate to the square of the velocity of liquid flow, and of the velocity at which movement of plunger It! takes place.

Inserted in the larger bore 86 there is a valve body 90 having a central bore 9| accommodating a ball valve 92 which is spring-pressed against a seat 93 by a spring 94 whose compression may be adjusted by means of a screw-threaded plug 95. Bore 9| below valve 92 communicates with reservoir 13 via ports 9la. Ball valve 92, as will be seen, closes kite its seat to prevent flow of oil from reservoir I3 into cylinder II, and opens, against the pressure of spring 94, to allow liouid fiow from cylinder H to reservoir 13. The initial pressure at which the valve will open depends on the setting of spring 94; but once the valve has opened its degree of opening then depends, in substantially straight-line relation, on the pressure and velocity of liquid fiow through it. The gradient of that straight line function depends upon the setting of the valve spring.

A relatively large valve 96, seated on passages 91 by a light spring 98, opens to allow free passage of liquid from reservoir 13 to cylinder II when plunger 10 moves upwardly.

Damping action due to orifice 8! alone is proportional to the square of the velocity of bolster and plunger moverrent. Damping due to the valve 92 alone is a constant force whose magnitude is governed by the force of spring 94. At any given setting of spring 94, the damping action is due to orifice 81 as long as the oscillation velocities are below the point of raising pressure sufficient to open valve 92. At higher velocities that valve opens and the damping force is then substantially constant until the velocity falls to the point where valve 92 closes. With valve 92 open, its linear damping effect, in general, predominates over that of orifice 81, although its relative predominance depends on the setting of needle valve 88 and on the area of valve 92.

Figs. 9, 10, and 11 are fragmentary views showing a modified arrangement of the supporting springs and snubber. In these views the side frame of the truck is designated generally by the numeral 22d, and the bolster by the numeral 35d. The spring plank is designated 25c and the frame platform on which the end of the spring plank rests is designated 21d.

The opening 26d in the frame which accommodates the spring plank, the bolster and the supporting springs, is somewhat wider than that shown in the preceding figures, owing to the fact that the springs are arranged in plan in a triangular formation. The frame opening is of suflflcient dimensions not to limit the threedimensional movement of the bolster in the springs and rollers.

The spring unit as here shown is composed of three single springs 40d which are arranged, in plan, in a triangular formation symmetrically with relation to the lateral axis B of the bolster, as may be seen from Fig. 9. As seen in that figure one of the three springs is arranged on axis B and the other two are equally and oppositely spaced with relation to that axis. And, although the three springs of the unit are not specifically arranged symmetrically witfirelation to the vertical central axis of side frame 22d, they are arranged so that the central vertical axis of their combined vertical thrust is substantially coincident with the central vertical axis of the side frame. The three springs are seated at their lower ends on the outer end of spring plank 25c, as seen in Figs. 9 and 10. Their upper ends carry a spring seat plate 4 Ie the plan configuration of which is shown in dotted lines in Fig. 9. This spring seat plate has roller seats 50d, and the underside of the upper wall of bolster 35c has downwardly facing roller seats Sid, these seats taking rollers 52d between them and being of the same configurations and functional performances as has been before mentioned and will be later described in detail. The spring seat plate Me is in no manner confined or guided by the frame; the frame opening 26d being large enough to allow all movements of that plate without contact.

Although we show this form of our invention as including the lateral roller action; that may be omitted in the same general manner as we have explained in connection with Figs. 1 and 8.

In this modified form of our truck the snubber 60d, at each end of the bolster, may conveniently be located directly on the central lateral bolster axis B, owing to the fact that there is sufiicient space between the two outer springs to accommodate the snubber in the manner shown in the drawings.

Generally speaking, the actions and functions of the modified form of Figs. 9 to 11 are the same as those of the form first described, and the subsequent discussion of functional performance will deal with both forms. The form of the last described figures has the advantage that the snubbers may be axially located with reference to the bolster, with the snubbers still kept within the clearance limits which are imposed by recognized railway practice. 0n the other hand, the general design shown in Figs. 1, 2, 3 and 8 has the relative advantage of allowing a shorter wheel base for the truck. In both forms the brakes and brake rigging (not shown) are hung solely on the side frames-not on the bolster-so as not to interfere with the free floating action of the bolster.

As we have previously stated, a purpose of the present invention is to provide a truck, preferably interchangeable with trucks in present use, which will give the car body a, free floating suspension enabling safe operation at speeds substantially higher than present safe speeds, on existing roadbeds and under the limitations existing at present in railway practice. One of those limitations is the permissible coupler height variation between empty and full loaded conditions, limited by present rules to a maximum of three inches. To keep safely within that figure we have selected two and one-quarter'inches as the allowable height variation due to load, and within that limitation have designed the spring sets to be as soft as possible in their vertical rate. Assuming that limitation and a lading of, say, fifty tons, or 12.5 tons per car corner, then the vertical spring rate for each of the two spring units on the truck becomes 11,100 pounds per inch. This rate, which gives about 110 cycles per minute in vertical oscillations, is much softer, and has lower frequencies than most spring systems which have been used or proposed for freight cars. (For the last figure a total load of 130,000 pounds, including 30,000 pounds of car body is allowed.)

In association with this relatively soft vertical action, and to carry the car body in fully floating condition on a single set of springs, it is desirable to make the transverse rate of those springs relatively high. as springs go. In our design of the springs. the transverse rate is about as high as the vertical rate: under li ht load the transverse rate for each spring unit is about 11.000 pounds per inch. The transverse rate (relative to axial rate) of the s rings for the form of Fig. 8. or when no lateral roller action is used, may be somewhat less than that just given. This relation of rates is attained in the design of the springs, one controlling factor being the ratio of coil length to coil diameter. As a specific instance of design for the particular load figures given above. the following spring figures are given. In the form of Fig. 1 where each unit comprises two nests. the large outer springs have a pitch diameter pf 10.5 inches. The steel spring rod is ill inches diameter. Overall diameter is 12.2". The material of all spring coils is highcarbon spring steel with a tension modulus of about 30.000900 p. s. i. and of shear about 11.000.000.

The intermediate sprin coil is composed of 11%" diameter rod on a pitch diameter of about 7%". The inner s ring is of ii" rod on a pitch diameter of about 4%".

The full height of all three coils is about 111'; inches and the height under li ht load, say 15.000 pounds per truck is about 10.875 inches. Height under maximum total load (car, and the fifty ton lading) is about 2% inches less than the full height, or about ill-l inches. The minimum, closed. height is about '7 inches, allowing about 1%" for relative downward movement of the fully loaded body without closing the springs. The dotted line showings at 35L in Fig. 1 show the bolster in about its lowermost position. Under light load (empty car) a vertical distance of about 2.25" is allowed over the bolster in frame openings 28 for relative upward movement. The same figures of spring rates per unit, and of relative height and clearance apply to the three spring unit shown in Figs. 8, 10. Each of the three springs is composed of 1%" diameter rod on a pitch diameter of 9 Fore and aft (longitudinal) clearance .of the bolster in frame openings 26 is about one inch each way. This is much more than ample to take care of the relative longitudinal movement of the truck with relationto the body; the high transverse spring rate limits the relative longitudinal movements of the truck" and at the same time prevents transmission of longitudinal truck vibrations to the car body. The longitudinal forces which have to be absorbed by the springs are relatively small because the truck, of much W65 given above are an illustration) to take full.

10 less mass than the body, is freely movable longitudinally.

It is desirable that the car body be given a rather large lateral freedom of spring opposed movement; and that fact, together with the fact that the transverse rate of a coil spring decreases with increase in axial (vertical) load.

lead to the desirability of modifying the lateral action of the spring units. That is done by utilizing the described roller cam action whose lateral rate is directly proportional to the imposed load. The ratio of imposed load to lateral cam rate'for different lateral displacements is determined by the shape of the roller seats. The seat design shown here is one in which the two opposite seats for each roller in normal position, form the opposing halves of an elliptic formation having a minor diameter (diameter of the roller) 01' two inches, and a major diameter of about four inches. With this seat formation the rollers allow a total lateral movement of about one inch each side of center. From about V inch to 1% inches each side of center is allowed by the springs depending on load. The total result is to allow a somewhat greater lateral movement-under any given lateral thrust-than would be allowed by the springs alone; and also to provide an opposing force-rate of the combined spring and rollercam mechanism -which is more nearly proportional to the vertical load, or mass of the car body and its load.

The spring units allow and take the threedimensional bolster movements wholly by resilient distortion. Movements transverse of the springs (longitudinal and lateral movements of the bolster) are taken purely by transverse spring distortions and do not cause rocking movements of the springs with reference either to the frames or the bolster. The action is as if the lower and upper bases of the springs were positively secured to the frame and bolster.

tact with the frame and bolster throughout all transverse distortional actions. The transverse rate of the springsgcan be assumed to be constantfor any particular load. This is essentially true since the springs are designed to be very stable under all axial loads experienced in service. Since the supported mass is much less at light car than at maximum load, and the transverse spring rate is essentially constant, much higher transverse accelerations are required to produce a given deflection at light car than with a loaded car, i. e., the transmissibility of the springs to transverse shocks will be much greater at light car than at the loaded car condition.

The lateral rollers have a lateral characteristic v which the lateral roller movement is not used, the v lateral movement of the bolster is under the control of the springs alone, preferably at a somewhat lesser transverse spring rate.

In all cases the springs are designed (the fig- The springs have sufficiently large diameters in proportion to their lengths that their bases remain stably in concognizance of the additional stresses induced by lateral forces and lateral distortions of the springs; so that, within at least the limits of lateral movements given above, the lateral spring rates remain substantially constant.

Each spring unit supports its respective .bolster end independently so that each end may move vertically and laterally independently of the other-end. The independence of those vertical movements is one factor that plays an important part in the action of the snubbers in preventing or minimizing rolling of the car body when lateral movement takes place.

The snubbers, lying normally in lateral planes, have little or substantially no action with reference to longitudinal relative movements between the bolsterand the car body-and the truck frame. Their real action is with reference to relative vertical and lateral motions; their proportionate actions vertically and laterally depending on the angles at which they are set. At 45, as in Fig. 7, each snubber will have equal damping actions on vertical and lateral components of movement. At an angle more nearly vertical, as in Fig. 10, the vertical action will be preponderant. An angle of 45 from the vertical may be taken as typical; but the angle may be either greater or less than that.

On straight vertical movement, or on the vertical component of any movement, each snubber acts simply to check upward rebound oi the bolster and body.

This vertical action not only damps straight vertical oscillation of the bolster and body, but also damps and checks rolling action of the body by checking the relative upward movement of either side. (It will be understood that the connection between the body and bolster is such as to allow relativemovement of only one degree between them-mlative swivelling rotation in a horizontal plane about the vertical axis of the swivel connection at 36. The usual side bearings at 360 prevent relative rolling movements.)

Typically, but not as a limitation, the snubbers may be designed and adjusted for any given installation to have approximately a damping factor on a fully loaded car, with relation to movement along the axis of the snubber. If set at 45, each snubber then has a damping factor of approximately 7% on either a vertical or a lateral component of movement.

The snubber actions on lateral movements, or lateral components, require some further analysis. Assume for example that the body and bolster tend to move relatively toward the right in Fig. 1. The left hand snubber then comes into play, it being compressed in length. The right hand snubber, lengthening, is temporarily inactive. The left hand snubber opposes, damps, that movement toward the right. At the same time it tends to push the left end of the bolster and the left side of the body down. In that manner the side of the body, away from which the lateral movement is taking p ace, is either moved down or is opposed in rising. The tendency to lateral rolling is thus reduced or minimized.

The rollers and their seats also play a part in that action. On lateral movement the action of the rollers is to lift the bolster and body vertically. The lift at the right hand side (still considering movement toward the right) has little or no efiect on the right hand snubber as it is expanding. But the roller lift of the left hand and of the bolster tends to compress the left hand snubber in length and therefore tends to increase its snubbing action tending to push or hold the left side of the bolster and body down.

We claim:

1. In trucks of the type which include a pair of wheel and axle units, a pair of side frames carried thereon, and a truck bolster extending laterallybetween the two side frames and having a central swivel connection with a car body; the combination of two spring units which respectively and independently support the two ends of the bolster on the side frames, each spring unit embodying a coil spring having a normally vertical axis, stably supported at its lower end on the side frame and stably connected at its upper end with the bolster, and allowing three dimensional movement of the supported bolster end by longitudinal and transverse elastic distortion of the spring, each bolster end being free of constraint by the side frame, and two independently acting movement resistors connected between the respective side frames and of wheel and axle units, a pair of side frames carried thereon, and a truck bolster extending laterally between the two side frames and having a central swivel connection with a car body; the combination of two spring units which respectively and independently support the two ends of the bolster on the side frames, each spring unit embodying a coil spring having a normally vertical axis, stably supported at its lower end on the side frame and stably connected at its upper end with the bolster, and allowing three dimensional movement of the supported bolster end by longitudinal and transverse elastic distortion of the spring, each bolster end being free of constraint by the side frame, and two independently acting movement resistors of the hydraulic damper type each connected to the respective side frames and bolster ends by universal connections which normally lie on a diagonal line extending upwardly and laterally inwardly, each resistor acting to resist movement of the respective bolster end inwardly and upwardly along said line.

3. In trucks of the type which include a pair of wheel and axle units, a pair Of side frames carried thereon, and a truck bolster extending laterally between the two side frames and having a central swivel connection with a car body; the combination of two spring units which respectively and independently support the two ends of the bolster on the side frames, each spring unit embodying a coil spring located on a normally vertical axis with its lower end stably supported by a side frame and its upper end stably engaging the respective bolster end for its support, the axial length and the diameter of the spring being approximately equal, and the vertical axial spring rate and horizontal transverse spring rate being approximately equal, said spring unit allowing relative vertical, lateral and longitudinal movements of the bolster end solely by elastic spring distortion, and each bolster end being free of constraint by the respective side frame in all said directions of movement, and roller-and-cam means in series arrangement with each spring unit and allowing lateral movement only.

4. In trucks or the type which include a pair of wheel and axle units, a truck frame including a pair of side frames carried on said units and a truck bolster extending laterally between the two side frames and having a central swivel connection with a car body; the combination of two elastic units which respectively and independently support the two ends of the bolster on the side frames, each elastic unit being stably sup-' ported on its respective side frame and stably connected to its respective bolster end and allowing relative vertical, lateral and longitudinal movements of the bolster end solely by elastic distortion, each bolster end being free of constraint by the side frame in all said directions, two independently acting movement resistors connected to the truck frame and applied each to one end of the bolster and each resisting upward and laterally inward movements of its respective bolster end with reference to the frame. and roller-and-cam means in series arrangement with each spring unit and allowing lateral movement only with reference to the frame.

5. In trucks of the type which include a pair of wheel and axle units, a truck frame including a pair of side frames carried on said units and a truck bolster extending laterally between the two side frames and having a central swivel connection with a car body; the combination of two spring units which respectively and independently support the two ends of the bolster on the side frames, each spring unit embodying a coil spring located on a normally vertical axis with its lower end stably supported by a side frame and its upper end stably engaging the respective bolster end for its support, the axial length and the diameter of the spring being approximately 14 6 equal, and the vertical axial spring rate and horizontal transverse spring rate being approximately equal, each said spring unit allowing relative vertical, lateral and longitudinal movements of its respective bolster end solely by elastic spring distortion, and each bolster end' being free of constraint by the respective slde' frame in all said directions of movement, two*- independently acting movement resistors connected to the truck frame and applied each to one end of the bolster and each resisting upward and laterally inward movements of its respective bolster end with referenceto the frame, and roller-and-cam means in series arrangement with each spring unit and allowing lateral movement only with reference to the frame.

, PAUL K. BEEMER.

FRANCIS L. CARL-ISLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,044,847 Barber Nov. 19, 1912 1,550,307 Elliott Aug. 18, 1925 1,866,167 Lolley July 5, 19 2 2,058,623 Protzeller et al Oct. 27, 1936 2,161,811 Grebe June 13, 1939 2,165,702 Haushalter July 11, 1939 2,222,321 Pflanger Nov. 19, 1940 2,264,702 Latshaw Dec. 2, 1941 2,237,056 Manning Apr. '1, 1941 2,319,623 Nystrom et al May 18, 1943 2,371,621 Harwick Mar. 20, 1945

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