US3795201A

US3795201A - Railway car roll dampening friction device

Info

Publication number: US3795201A
Application number: US00321236A
Authority: US
Inventors: C Tack
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-01-28
Filing date: 1973-01-05
Publication date: 1974-03-05
Anticipated expiration: 1991-03-05

Abstract

An energy-absorber for swaying motion between the body and sideframe portions of a railroad car has a housing and a fulcrum adapted for mounting on the same portion of the car and has a lever pivoted on the fulcrum and adapted for sliding engagement with the other portion of the car. The housing contains a friction shoe having inclined wedging surfaces at its opposite ends and inner and outer wedge members having inclined surfaces mating with those of the shoe. The drive rod of the energyabsorber is pivoted to the operating lever and has an abutment engaging the outer wedge and has a compression spring around its inner end engaging the inner wedge. A spring of greater capacity in the housing produces friction increasing with the insertion of the rod and the shoe into the housing. Structure for providing maintenance-free operation over long periods of use is described.

Description

United States Patent FRICTION DEVICE [76] Inventor: Carl E. Tack, 157 Linden St.,

Elmhurst, 111. 60126 [22] Filed: Jan. 5, 1973 [21] Appl. No.: 321,236

Related U.S. Application Data [63] Continuation-impart of Ser. No. 6,473, Jan. 28,

1970, Pat. No. 3,731,638.

[52] U.S. Cl 105/199 A, 105/199 CB, 105/453, 267/9 A, 267/9 C, 308/138 [51] Int. B6lf 5/14, B61f 5/24, F16c 17/04 [58] Field of Search ..105/197 D, 197 R, 199 A, 105/199 C; 199 CB, 199 F, 199 R, 105/453; 267/9 A, 9 C; 308/138 [56] References Cited UNITED STATES PATENTS 1,347,898 7/1920 Eaton 105/199 R 2,497,829 2/1950 Baselt 267/9 C 2,574,788 11/1951 Janeway et a1 t 267/9 C 2,844,366 7/1958 Butterfield 267/9 C X 2,961,974 11/1960 Seelig, Jr. 105/453 X 3,043,241 7/1962 Ortner 105/199 CB 3,439,631 4/1969 Cope 105/199 R X Tack 1 Mar. 5, 1974 [5 1 RAILWAY CAR ROLL DAMPENING 3,514,169 5 1970 MacDonncll 308/138 3,731,638 5/1973 Tack 105 199 A Primary ExaminerRobert G. Sheridan Assistant ExaminerHoward Beltran Attorney, Agent, or Firm-Gary, Juettner, Pigott &

Cullinan [57] ABSTRACT An energy-absorber for swaying motion between the body and side-frame portions of a railroad car has a housing and a fulcrum adapted for mounting on the same portion of the car and has a lever pivoted on the fulcrum and adapted for sliding engagement with the other portion of the car. The housing contains a friction shoe having inclined wedg ing surfaces at-its opposite ends and inner and outer wedge members having inclined surfaces mating with those of the shoe. The drive rod of the energy-absorber is pivoted to the operating lever and has an abutment engaging the outer wedge and has a compression spring around its inner end engaging the inner wedge. A spring of greater capacity in the housing produces friction increasing with the insertion of the rod and the shoe into the housing. Structure for providing maintenance-free operation over long periods of use is described.

7 Claims, 14 Drawing Figures RAILWAY CAR ROLL DAMPENING FRICTION DEVICE This is a continuation-in-part of an application of the same inventor filed Jan. 28, 1970, Ser. No. 6,473, now

U.S. Pat. No. 3,731,638 issued May 8, 1973.

This invention relates to energy-absorption devices for railroad cars, and more particularly to a friction strut or frictional energy absorber for application to a freight car to permit high speed operation thereof without the problems of derailment, particularly on curves, limiting the operating speed before the invention.

In the interest of brevity, there are omitted from this application certain aspects of the fuller discussion of region 'of normal compression and, in addition, provides means to disable the energy absorber during return motion occurring immediately after separative motion substantially faster than the body-oscillation motion which occurs at critical car speed. As more fully discussed in'the co-pending application, the latter feature of operation permits rapid downward and return motions of the wheels at crossings and the like without transfer of shock to the body which would result if all approach motions of the side-frame and the body were opposed without discrimination therebetween.

The invention will best be understood, both generally and in detail, from consideration of the embodiments thereof illustrated in the annexed drawing, in which:

FIG. 1 is a more or less schematic fragmentary eleva-v tion view of a frictional energy-absorbing device of the invention mounted on a car body and slidingly engaged with the side frame of thetruck;

FIG. 2 is a vertical sectional view of a frictional energy-absorbing device embodying certain aspects of the invention;

FIG. 3 is a horizontal sectional view taken along the line 3--3 of FIG. 2;

FIG. 4 is a fragmentary view, partially in section and partially in elevation, of an improved embodiment of the invention;

FIG. 5 is a sectional view similar to the section of FIG. 4, but showing an altered position of the parts;

FIG. 6 is'a top plan view of the upper of two wedge members shown in FIGS. 4 and 5;

FIG. 7 is a sectional view of the wedge member taken along the line 77 of FIG. 6; 7

FIG. 8 is a view partially in elevation and partially in section taken along the line 8-8 of FIG. 4 in the direction indicated by arrows, with certain parts shown in elevation successively broken away in section for clarification of the relationship of the parts;

FIG. 9 is a top plan view of the lower of the wedges shown in FIGS. 4 and 5;

FIG. 10 is a side elevational view of the wedge of FIG. 9;

FIG. 11 is a sectional view along the line 11-11 of FIG. 5 in the direction indicated by arrows;

FIG. 12 is a sectional view along the line l2--12 of FIG. 5 in the direction indicated by arrows;

FIG. 13 is an angled or offset sectional view along the line l3l3 of FIG. 11; and

FIG. 14 is an enlarged fragmentary sectional view corresponding generally to a portion of FIG. 11 or 12, but showing the effect of wear-in of certain of the parts.

The illustration of FIG. 1 shows one manner of mounting an energy-absorbing device of the invention on a railroad car (four being normally employed but only one being shown) for the purposes set forth in the co-pending application earlier mentioned. The energyabsorbing device, generally designated 10, is mounted by. brackets 12 to a web 14 associated with the body bolster and extending across the lower portion of the end of the car body (not shown). A drive rod or actuator 16 of the energy-absorber l0 depends downwardly and its lower end is pivotally attached at 18 to the outer end of a lever or crank 20, the opposite end of which is pivoted at 22 on suitable ears 24 depending from the shear panel portion 26 of the body bolster assembly. The ears 24 thus constitute a fulcrum for the lever or crank 20. The crank 20 is in sliding engagement with a bearing plate 28 on the upper surface of the sideframe 30 of the car, upon which the wheels 32 are mounted in conventional fashion. The conventional spring-mounted truck bolster and pivotal mounting thereon of the body bolster are omitted from the drawing, the showing thereof being superfluous to understanding of the present invention.

The internal construction of the energy-absorbing device is shown in FIGS. 2 and 3. The housing or casing is formed by four corner-angle members 34. In the lower region, these are joined, preferably by welding, to four internal plates 36, which thus enclose the lower portion of the housing and also serve as friction surfaces as later described. At the top, the-angle members 34 are welded to an internally seated end cap 38 having a central aperture 40.

Loosely surrounding the rod or shaft 16 are upper and lower wedges or

wedge rings

42 and 44. Each wedge has a central aperture 46 of tapered diameter, being largest at the adjacent or facing surfaces and smallest at the opposite surfaces, but passing the rod 16 freely and loosely at all points to accommodate the slightly arcuate motion of the lower end of rod 16 to be later described. The periphery of each wedge ring is generally square and each wedge has the general outer shape of a truncated pyramid having minimum dimensions in the inner or facing region and maximum dimensions in the opposite region.

' Between the wedge surfaces of the

rings

42 and 44 are disposed friction shoes 48, each of an L-shaped horizontal cross-section having the outer surface of one arm in sliding engagement with one of the plates 36 and the outer surface of the other arm in sliding engagement with an adjacent plate 36. The upper and lower end portions of the shoes 48 are internally inclined in correspondence with the inclination of the wedge rings, which are in contact therewith only at the orthogonal faces, the comers of the pyramidal wedges being bevelled at 49 to avoid contact with the internal corner portions of the shoes 48. A flange or collar 50 on the external lower portion of the rod 16 constitutes an abutment engaging the outer surface of the lower ring 44, with a suitable washer 52 interposed. A coiled spring 54 surrounds the inner or upper end of the rod 16 and is compressed between the surface of the upper wedge ring 42 and a disk flange or washer 56, which is adjustably positioned by a nut 58 on the threaded inner or upper end of the rod 16.

A coiled spring 60, of much larger restoring-force or capacity than the spring 54, surrounds the entire upper portion of the movable assembly just described, being normally under relatively small compression between the end cap 38 and the radially outer portion of the upper wedge ring 42. The latter is formed with a rib 62 separating the radially inner seating of the end of the spring 54 from the radially outer seating of the surrounding heavier spring 60.

The energy-absorption characteristics of the construction shown in FIGS. 2 and 3, which may be called a friction strut, may be understood from consideration of the above-described construction. The moving portion of the assembly (the rod 16, the

wedges

42 and 44 and the shoes 48) slides in the housing against a frictional force determined by the lateral force spreading apart the shoes 48, which is in turn determined by the magnitude of the spring forces urging the

wedge rings

42 and 44 together. A minimum or biasing force is provided by the small spring 54. This spring exerts no longitudinal force urging the rod 16 in either direction, and the lateral force exerted on the shoes 48 by this spring may be considered more or less uniform at all times.

The larger spring 60 serves a dual purpose, both biasing the entire movable assembly outward and exercising variable control of the frictional resistance to motion. The friction established by the light biasing spring 54 is relatively small and is normally effective primarily when the rod 16 is in a wholly extended position, i.e., with the spring 60 under substantially no compression and no inward force exerted at the outer-end pivot point 18. The position assumed by the rod 16 in this condition may be determined by the adjustment of the nut 58, which is usually adjusted to sufficient tightness so that lifting of the lever from engagement with the side-frame which normally supports it does not produce removal of the shoes 48 from the housing. A pin or similar stop-member (not shown) is normally inserted across the housing at the outer end to limit the outward motion and thus facilitate assembly as well as permit adjustment of the nut 58 to be made without restriction to such a minimum friction requirement if it is desired to make the first portion of an inward stroke of the rod 16 essentially entirely frictionless. If so desired, the adjustment of the nut 58 can be used as a trimming adjustment, to provide a pre-established frictional damping or opposing force to inward motion of the rod 16 at any predetermined inward position.

The motions and forces produced by the energyabsorbers of the invention in the coupling between the body and the side frames will now be briefly described, omitting certain more detailed explanation of the purposes served and advantages obtained in operation of a railroad car which appears in the earliermentioned co-pending application. As already indicated, the lowermost portion of the crank is in frictional sliding contact on the bearing plate 28 atop the side frame 30 leaving the truck free for pivotal motion at curves without the use of universal joints or any similar constructions introducing problems of complexity and mechanical failure. The energy-absorbers 10 are installed at a height such that with the car stationary on a level track, the rod 16 is driven by the weight of the car body part-way into the housing. The degree of pen etration in this median or normal position will of course vary somewhat with the weight of the load in the car. It is of course possible to match a particular detailed description or adjustment to the car each time it is loaded (or emptied) but the mode of operation is to a large extent self-compensating for degree of loading because of inertia change. In this normal or median position, the compression of the large spring 60 is relatively small as compared with the degree of compression which occurs on alternate sides upon the occurrence of rocking relative motion between the body and the side frames.

When rocking motion occurs on a straight track, damping action occurs alternately on one side of the car and then the other. As the rod is driven into the housing, the pressure of the spring 60 on the wedge rings 42 and 44 increases, thus increasing the friction between the shoes 48 and the plates 36 to dissipate oscillation energy of the springs of the car (not shown). However, this frictional dissipation is essentially unidirectional. When the motion reverses, i.e., as the car body and the side frame commence to separate, the spring 60 forces the rod 16 outward. Obviously, the energy-absorber 10 presents no frictional resistance to this separative motion. On straight uninterrupted track in well-maintained condition, cranks 20 on both sides of the car are at all times in contact with their corresponding side-frame plates 28. However, in the event of relatively large separative excursions, the rod 16 may reach the outer limit of its travel before the separative motion ends, in which event contact between the crank 20 and plate 28 may be broken, until the motion is arrested by the action of the absorber on the oppsite side, and then again reestablished to commence the compression of the spring 60. Such a departure from contact also occurs for a short time in the event a downward wheel excursion, even though of small magnitude, is too fast to be followed by the lever as now to be discussed.

Despite its effectiveness in damping car body oscillations, the energy-absorber of the invention produces a minimum of interference with the action of the car springs in isolating the car body from impact-type rapid excursions of the wheels such as at crossings, sudden clips at very soft joints, etc., and in high-speed operation on rough track. Although the release of friction within the damping device and outward return of the actuator rod are sufficiently fast so that swaying of the car (except of very large magnitude) does not produce disengagement of the crank or lever 20 from the bearing plate 28, small downward excursions and returns of the wheels, if sufficiently fast, are not followed due to the finite time required for release of friction within the damping device at the instant when the side frame suddenly drops down and also the minimum friction established by the bias spring 54, which limit the speed of ejection of the rod and the shoe. The greater the compression of the spring 60 at the time of such an occurrence, the greater the time lag before the lever 20 is able to follow such a rapid downward motion. Accordingly, the rapid upward return of the wheels produces minimal jarring of the load even when (as is uncommon) such a track discontinuity is encountered at an instant when the frictional force within the damping device is very high. The minimum friction is desirably adjusted (or may less advantageously be fixed by suitable precise selection of the larger springs, if bias springs are omitted) so that moderatly large body oscillations are wholly followed at the cars critical speed but separative motions occurring very much faster than this at either side quickly break the contact.

I An improved embodiment of the energy-aborber or friction strut of the invention is shown in FIGS. 4 through 14, in which portions or elements which are substantially identical with the embodiment already described bear the same reference characters. Portions of the assembly are altered in a manner found to greatly improve smooth and maintenance-free operation over long periods of use.

The external corners of the upper and

lower wedges

64 and 66 and the corresponding portions of the shoes 68 are differently shaped and related than in the embodiment of FIGS. 2 and 3. As already indicated, in that embodiment clearance is provided at the internal angles of the L-shaped shoes, all contact between the wedges and the shoes being along orthogonal interfaces excluding the corners. It will be noted that with this construction, i.e., with sufficient of the pyramidal corners of the wedges bevelled away to avoid all contact with the internal corner of a shoe, both the internal shaping of the .corner of the shoe and the shape of the mentioned bevel are unimportant. In the embodiment of FIGS. 2 and 3, the internal corner or angle of each L-shaped shoe is merely formed with a convenient arbitrary degree of roundness and the corner bevels 49 on the wedges are likewise more or less arbitrarily determined, subject only-to the limitation of having suffi-' cient corner-removal in all horizontal planes to avoid contact with the rounded internal corner of the shoe. Thus in the illustration of FIG. 3, it will be seen that the bevelled corners 49 of the wedge form planes of an inclination producing greater bevel width with increasing horizontal dimension, the slope of the plane of the bevel being more or less arbitrarily selected.

The improved embodiment employs a substantially different relation between the external corners of the pyramidal wedges and the internal corners of the L- shaped shoes (i.e., the end portions of the shoes which receive the oppositely disposed wedges). The construction of FIGS. 2 and 3 is found to require great precision of matching of the abutting surfaces of the wedge and the shoe, respectively, to produce and maintain the desired smooth and troublefree operation. Any roughness or deviation from smooth and exact correspondence between the internal half-pyramidal shape of the end of the shoe and the external pyramidal shape of the wedge fitting therein except at the corners is found to produce jamming and locking.

In theory, such effects may be avoided by sufficiently high precision in manufacture, but this is difiicult as a practical matter. As a result, the construction of FIGS. 2 and 3 in practice requires a prolonged period of break-in, either installed on a railroad car or with artificial simulation of the action thereof, before operation is fully reliable. In such break-in, it is normally found necessary to occasionally free the device from a jammed or locked condition, which occurs with decreasing frequency as use continues until reliably smooth operation is'ultimately obtained when wear on the parts finally produces exact mating.

The difficulty in producing this smooth mated condition without prohibitive precision in manufacture, and without extended break-in during which jamming and locking may occur, it avoided by the improved construction.

In essence, the construction of FIGS. 4 to 14 provides what might be termined a temporary or short-term manner of cooperation of the parts which gives fully satisfactory maintenance-free operation during a breaking-in period which is not externally observable as a distinct performance phase but produces a transition to a final or longterm mode of operation which is not only equivalent to, but indeed somewhat superior to, the long-term operation obtainable only after a long break-in period involving freeing of occasional jamming with the construction previously described.

In the

wedges

64 and 66 of the improved construction, the bevelled planar corner surfaces 70 which separate the inclined planar sides 72 are mated to corre sponding inclined planar surfaces 74 in the angles of the L-shaped shoes 68. Both the external corner surfaces 70 on the wedges and the internal corner surfaces 74 on the shoes are rectangular, i.e., of equal width along their length. As best seen in FIGS. 11 and 12, in the as-manufactured condition, the internal corner surfaces 74 of the shoes are slightly wider than the external corner surfaces 70 on the wedges. The effect of this is that in the as-manufactured condition, contact between the shoes and the wedges is solely at the corners, the arms of the L-shaped shoes being substantially entirelyout of contact with the sides 72 of the wedges in this condition. The force on the shoes producing friction with the plates 36 is thus exerted substantially solely at the corners, but is distributed between the orthogonal components into which this force is inherently resolved in producing the friction. The application of the wedging action at only the two diagonally opposite corners, rather than at the four sides of a square, eliminates the primary cause of problems with jamming during the period of break-in. 7

As use progresses, the difference in width of the wedging surfaces at the diagonally disposed interfaces is gradually reduced until there is ultimately reached the condition of abutment of all of the mating surfaces, both at the four sides and at the'diagonally opposite corners, as shown in the enlarged view of FIG. 14, showing an exemplary pair of adjacent wedging interfaces. To prevent any possible binding, grooves 75 (seen only in the enlarged FIG. 14) are formed at opposite edges of the corner surfaces of shoes 74. After the break-in period, all of the mating surfaces thus cooperate in the wedging action. In addition to the advantage regarding elimination of malfunction, and thus fully practicable usability during break-in, the already-long useful life of the device is further extended by the longterm utilization of the corner portions in the wedging action, as compared to the previously described construction wherein the corners are not utilized. it will be noted (best seen in FIG. 12) that in the regions where the cross-section of the wedges is small, and the cross section of the shoes correspondingly large, the added contribution of the corner portions to the wedging action is major.

The improved embodiment also differs from the one earlier described in the construction by which the drive rod 76,'otherwise similar to the drive rod 16, is coupled to the wedge-and-shoe assembly to produce reciprocation thereof in the housing. The drive rod 76 has a flange 78 welded thereto at 80, on which is seated a washer 82. The flange 78 and washer 72, rather than being planar, have a concave generally spherical curvature, and the lower end 84 of the lower wedge 66 is spherically convex to match. As seen by comparison of FIGS. 4 and 5, the lower wedge 66 is thus efficiently isolated from all non vertical components of motion of the rod 76. Such components of motion arise from two sources. First, as earlier mentioned, although the motion of the pivot 18 at the outer end of the rod 16 (rod 76 in the improved embodiment) is generally linear, it has an arcuate component about the pivot 22 as a center. Also, pivoting of the car truck with respect to the car body inherently produces slight sidewise motion of the outer end of the rod with practical constructions.

With the spherical-interface coupling between the rod 76 and the lower wedge 66, a substantial angle of tilt of the rod in any direction with respect to the housing of the energy-absorber produces no adverse effect on its proper operation. The radius of curvature of the spherical interface constituting, in essence, a ball-andsocket coupling between the drive rod and the lower wedge, is substantially at the longitudinal center of the shoe, so that the aperture size in the wedges required to accommodate the tilting of the rod is minimized. This predetermination of the direction of tilt also permits the shaping of the apertures in the wedges in a manner wherein the apertures are largest in crosssection where the wedges are largest in cross-section.

Persons skilled in the art will readily devise many variants substantially departing from the illustrated embodiments, but nevertheless utilizing the teachings of the invention. The scope of the protection to be afforded the invention should accordingly not be limited to the specific embodiments illustrated.

What is claimed is:

l. A motion-damping device for a railroad car having body and side-frame portions comprising an elongated housing adapted to be attached to one of said portions and having a longitudinally extending internal friction surface, a friction shoe guided for sliding motion along said surface and having inclined wedging surfaces at opposite ends thereof, inner and outer wedge members having inclined surfaces mating with the respective inclined surfaces of the shoe, a drive actuator extending into the housing and having its inner end inward of the inner wedge members, an abutment on the actuator engaging the outer wedge member in the direction to drive it inwardly, a compression spring on the inner end of the actuator urging the inner wedge member outwardly to maintain a minimum friction, and a compression spring of greater capacity seated in the inner end of the housing and also urging the inner wedge member outwardly to produce friction increasing with insertion of the actuator and the shoe into the housing in response to external force and to return the actuator and.

the shoe outward when external force is withdrawn.

2. The motion-damping device of claim 1 having the wedge members of generally square cross-section and having two shoes of L-shape cross-section.

3. The motion-damping device of claim 2 having additional mating wedging surfaces on the internal corners of the shoes and the diagonally opposite external corners of the wedge members thereby engaged, the wedging surfaces at the corners being initially substantially the sole points of contact between the wedging members and the shoes.

4. The motion-damping device of claim 1 having the abutment and the portion of the wedge member engaged thereby of mating generally spherical shape.

5. The motion-damping device of claim 1 having a lever pivotally engaged with the outer end of the actuator and adapted to slidingly engage the other portion of the car and a fulcrum member adapted to be mounted on the same portion of the car as the housing and pivotally engaged with the lever.

6 A motion-damping device for a railroad car having body and side-frame portions comprising a housing adapted to be mounted on one of said portions, an actuating member extending from the housing, a lever pivotally engaged with the outer end of the actuator and adapted to slidingly engage the other said portion of the car, and a fulcrum member adapted to be mounted on the same portion of the car as the housing and pivotally engaged with the lever, the housing containing friction means opposing insertion of the actuating member and responsive to inward driven motion of the actuating member to increase the friction, spring means to return the actuating member outwardly to follow the separating relative motion of said portions of the car produced by car-spring oscillations, and means to maintain substantial friction opposing said spring means to prevent following by the actuating member of the fast separative and return relative motions of said portions of the car produced by track discontinuities at crossings and the like.

7. The motion-damping device of claim 6 having a sliding assembly within the housing having an apertured outer member, the actuator member extending through the outer member and having an abutment portion engaging the portion of the outer member surrounding the aperture, said abutment portion and said surrounding portion being of mating spherical shape.

Claims

1. A motion-damping device for a railroad car having body and side-frame portions comprising an elongated housing adapted to be attached to one of said portions and having a longitudinally extending internal friction surface, a friction shoe guided for sliding motion along said surface and having inclined wedging surfaces at opposite ends thereof, inner and outer wedge members having inclined surfaces mating with the respective inclined surfaces of the shoe, a drive actuator extending into the housing and having its inner end inward of the inner wedge members, an abutment on the actuator engaging the outer wedge member in the direction to drive it inwardly, a compression spring on the inner end of the actuator urging the inner wedge member outwardly to maintain a minimum friction, and a compression spring of greater capacity seated in the inner end of the housing and also urging the inner wedge member outwardly to produce friction increasing with insertion of the actuator and the shoe into the housing in response to external force and to return the actuator and the shoe outward when external force is withdrawn.

6. A motion-damping device for a railroad car having body and side-frame portions comprising a housing adapted to be mounted on one of said portions, an actuating member extending from the housing, a lever pivotally engaged with the outer end of the actuator and adapted to slidingly engage the other said portion of the car, and a fulcrum member adapted to be mounted on the same portion of the car as the housing and pivotally engaged with the lever, the housing containing friction means opposing insertion of the actuating member and responsive to inward driven motion of the actuating member to increase the friction, spring means to return the actuating member outwardly to follow the separating relative motion of said portions of the car produced by car-spring oscillations, and means to maintain substantial friction opposing said spring means to prevent following by the actuating member of the fast separative and return relative motions of said portions of the car produced by track discontinuities at crossings and the like.