US2950017A - Snubbing devices - Google Patents

Description

Aug. 23, 1960 s. H. FILLION ErAL 2,950,017

SNUBBING DEVICES Filed Bay 6, 1958 3 Sheets-Sheer. 1

INVENTOR d ij ZZ a flaw Aug. 23, 1960 s. H. FILLION ETAL SNUBBING- DEVICES I5 Sheets-Sheet 2 Filed May 6, 1958 lllllll lblll 'Aug; 23, 1960 s. H. FILLION ETAL 2,950,017

- SNUBBING DEVICES Filed May 6, 195a s Sheets-Sheet. :5

FIG. 4

li ll 1 W// ATTORNE S United rates PatentG 2,950,017 SNUBBING nnvrcns Stanley H. Fillion, Scarsdaie, and Arthur E. Schaefer,

New Hyde Park, N.Y., assignors to Waugh Equipment Company, a corporation of Maine Filed May 6, 1958, Ser. No. 733,376

14 Claims. (Cl. 213-8) This invention relates to snubbing or braking devices for retarding the movement of a movable member relative to a stationary member in either of opposite directions from an initial position against the action of resilient restoring means. More particularly, the invention is concerned with a novel snubbing device, which is of simple construction and high capacity. In the new device, the braking forces are progressively applied, as the movable member is moved away from its central position, through a plurality of contacting friction surfaces and, when the member is returned to its initial position by the restoring means, the adhesion between the surfaces is progressively broken. As a result of such progressive action on release, the likelihood of the device sticking, so that restoration of the movable member, to its central position is prevented, is greatly reduced. The device may be employed in various applications but offers special advantages when installed on a railway car having a cushion underframe with a draft and bufiing column to retard the movements of the column. An embodiment of the invention for such railway car use will, accordingly, be illustrated and described in detail for purposes of explanation.

Cushion underframes have been employed on railway cars for many years and commonly include a rigid draft and buffing column extending substantially throughout the length of the car body and connected at its ends to the couplers. Movement of the column lengthwise in either direction from its initial position is resisted by resilient means in the form of one or more coil springs connected to the column and to the car underframe and part of the force applied to the column and causing movement thereof is dissipated by frictional heat generated by movement of the column on its supports, such as the bolster center filler castings.

The present invention is directed to the provision of a novel snubbing or bralc'ng device, which may be used 1 with a cushion under-frame on a railway car to provide a greater absorption of force applied to the draft and boiling column of the underframe than is possible in present installations. In addition, the new device is so constructed that it facilitates restoration of the column to its central position after release of force applied thereto through a coupler.

For a better understanding of the invention, reference may be made to the accompanying drawings, in which Fig. l is a fragmentary longitudinal sectional view of a cushion underframe provided with a new braking device;

Fig. 2 is a plan view, with parts broken away, of the device installed in a cushion underframe;

Figs. 3 and 4 are sectional views on the lines 3-3 and 44 of Fig. 2, respectively; and

Fig. 5 is a view similar to Fig. 3 showing the device in operation.

In the drawings, the snubbing device is shown in use on a tank car, in which the tank is mounted on an underframe generally designated 11 and carrying a rigid PatentedAug. 23, 1960 draft and bufling column 12. The column extends from end to end of the underframe and may be made, as is customary, of a pair of Z- bars 13, 14 having the edges of their top flanges welded together. The column is supported by the center filler castings 15 of the car bolsters, as shown in Patent 2,818,982 of McCaiferty and Johnson, issued January 7, 1958, and, at each end, it is connected to the shank of a coupler 16 by a key 17. The ends of each key 17 lie in elongated slots in the side walls of the column and the inner end of the shank of each coupler is engageable with a cushioning device 18, which is illustrated as made up of a stack of rubber springs 19 having interposed separator plates 20 and lying between follower blocks 21, 22. The block 22 lies in contact with stop plates 23 secured to the inner faces of the walls of the column and the cushioning device is supported on a plate '24 attached to the bottom flanges of the column. I

The snubbing device of the invention comprises a housing 25, which is generally of U-shape and has side walls 26, 27 secured, as by riveting, to the opposed faces of the walls of the column. A cam assembly 28 extends through the housing and the assembly illustrated is made up of three bars, of which the lowermost 28a rests on the the bottom wall of the housing. The middle bar 28b has a section at one end, which increases in width toward that end and is of increased thickness, and the end section is secured to the bottom bar 2841 and the top bar 280. The end section projects beyond the ends of the bars 23a and 280 and is secured in place between the upper and lower members of a fork 29 integral with the center filler casting 15 of adjacent bolster by pins 30 passing through openings in the bar and fork and held in place by keys 31. The portion of the top bar adjacent the housing 25 is formed at its top with cam surfaces 32, 33, which extend lengthwise of the bar and diverge upwardly.

A friction plate 34 is interposed between the bottom and middle bars 28a, 28b and the ends of the plate enter openings in the walls 26, 27 of the housing, the vertical edges of the openings at opposite sides of the plate serving as stops. A similar plate 35 lies between the middle and top bars 28b, 28c and the ends of plate 35 also lie within the openings in the walls of the housing. As shown in Fig. 3, the plates 34, 35 are of the same width and the openings in the housing walls receiving the ends of the plates are wider than the plates with the difference in width between plate 34 and its opening less than the difference in width between plate 35 and its opening. If preferred, the openings may be of the same width and the plates of different widths.

The flat surface of a shoe 36 of semi-cylindrical form rests upon the cam surfaces 32, 33 of the bar 280, when the column is in central condition, as shown in Fig. 3. A housing plate 37 rests upon the shoe with the shoe entering a semi-cylindrical cavity in the under surface of the plate. The housing plate is formed with lugs 37a, 371) at its ends, which lie within recesses 38, 39' in the opposed walls 26, 27 of housing 25. The recesses are of greater width than the lugs for a purpose to be described.

A stack of leaf springs 40 rests upon the top of the housing plate 37 and is held in contact with the plate by a cap 41, which is secured to the housing plate by a plurality of bolts 42. The assembly of the shoe, springs, and cap is held in contact with the shoe 36 by bolts. 43, which connect the cap and the bottom of the housing.

The draft and bufling column 12 of the car is provided with the usual resilient means resisting the movement of the column in either direction by forces applied to the couplers and, upon release of the forces, the resilient means act to restore the column to its initial central position. The resilient means may take the form of one or more coil springs connected to the column and to a bolster center filler casting as shown, for example, in Simonson Patent 2,652,158, issued September, 15, 1953.

The operation of the snubbing device will be understood from the following. Upon the application of a force tending to move the column to the left, as shown in the drawings, for example, the housing moves simultaneously with the column. There are, however, such clearances between the parts of the snubbing device that, during the initial travel of the column for a predetermined distance, the device is without effect. The length of the free initial travel of the column depends on the clearances in the assembly, the adjustment of the bolts 42, 43, etc., and may be, for example, 2". During the initial travel of the column, the shoe 36 moves angularly to make good contact with the cam surface 32 and the lugs 37a, 37b on the housing plate are engaged by the walls at the trailing sides of the recesses 38, 39 in the opposed walls of the housing 25. Also, during the initial travel ofthe column, the lower friction plate 3-4 is first engaged by the trailing surfaces of the openings in the housing wall and, shortly thereafter, the upper friction plate 35 is similarly engaged by such surfaces. Upon continued movement of the column past the initial stage, the housing plate 37 is moved with the housing and causes the shoe 36 to move up the slope of the cam surface 32. As a result, the spring bundle is compressed and the bars of the cam assembly 28 are caused to grip the friction plates 34, 35. As the movement of the column continues, the pressures applied to the friction plates through the cam bars by the shoe increase with the absorption of energy, which is dissipated as heat.

At the end of the travel of the column, the parts of the snubbing device are bound tightly together and, if it were necessary to release the adhesion between all friction surfaces simultaneously, a great restoring force would be required. However, in the present snubbing device, the provision of the clearances between the lugs on the shoe housing plate and the walls of the recesses in the housing and between the ends of the friction plates and the walls of the openings in the housing makes such a large restoring force unnecessary and prevents sticking of the device, which would interfere With restoration of the column to its central position. Thus, as the column starts to return to the right, the adhesion between the lower surface of bar 28a of the cam assembly and the surface of the bottom of the housing 25, on which the bar rests, is first broken. During the initial return movement of the housing relative to the cam assembly, the shoe has remained at rest because of the clearance between the lugs 37a, 371) on the shoe housing plate and the walls of the recesses 38, 39 of the housing and the friction plates 34, $5 have also remained at rest, because of the clearances between their left-hand edges and the opposed surfaces of the walls of the openings in the housing, in which the ends of the plates are received. After a short travel of the column and snubber housing to the right, for example, A, the clearance between the walls of recesses 38, 39 and the lugs 37a, 37b on the shoe housing plate 37 is eliminated and continued movement of the column breaks the adhesion between the friction surface on the shoe and the cam surface 32. At this time, the two friction plates 34, 35 are still at rest and are held tightly between the bars of the cam assembly but, after an additional movement, such as /2", of the column to the right, the left-hand edge of the lower friction plate 34 is engaged by the Opposed surfaces of the walls of the openings in the housing and its adhesion to the bars 28a, 28b of the cam assembly is broken. Finally, the left-hand edge of the upper friction plate 35 is engaged by the walls of the openings in the housing and its adhesion to plates 28a, 28c of the cam assembly is broken. The adhesion of all parts of the snubber to the bars of the cam assembly has now been broken and the restoring means can act to move the column to its initial central position against the dynamic friction only of the snubber.

The use in the compression means of the snubbing device of a damped resilient element, such as a stack of leaf springs, acting on the shoe offers a special advan tage in that, because of the dissipation of energy by damping action during compression, such damped element exerts less force on release than during compression. in the case of an undamped resilient element, such as a coil spring, the force exerted on release is substantially the same as that exerted during compression. In the device, the force exerted by the resilient element on release determines the tendency of the device to stick on release and it is thus desirable to use an element, which gives the device the maximum capacity without excessive tendency to stick. If an undamped element were, used, the liability of the device to stick would limit the permissible capacity of the device but, by the use of a damped element, increased capacity may be obtained without a corresponding increase in the tendency to stick.

It will be apparent from the foregoing that the new snubbing device provides a simple means for absorbing a substantial amount of energy and it may be employed advantageously to add to the capacity of a cushion underframe. In such use, its progressive braking action causes it to operate smoothly and its progressive release makes possible the restoration of the column of the underframe to its initial central position without the use of excessive restoring force.

We claim:

1. A device for retarding the movements of a movable member relative to a fixed member in opposite directions from a central position, which comprises a housing secured to one member, a cam assembly secured to the second member and extending through the housing, the assembly including parallel bars extending horizontally and connected in spaced relation, one bar of the assembly having surfaces at one side of the assembly extending lengthwise of the bar and diverging in a direction away from the assembly, a friction plate extending transversely between and in contact with each two adjacent bars, a pair of spaced stops on the housing at each end of each plate, the ends of each plate lying between a pair of the stops and the width of each plate being less than the distance between the stops of the pairs associated with the plate to provide a limited freedom of movement of the plate in the direction of its width between the stops, a shoe engaging the outer bar of the assembly and movable by the housing along the diverging surfaces, and means on the housing acting through the shoe to compress the bars and plates, when the shoe is on one of the surfaces.

2. The device of claim 1, in which the widths of the plates and the spacings between the stops associated with respective plates are varied to give each plate a limited freedom of movement differing from that of each of the other plates.

3. The device of claim 1, in which the compression means include a damped resilient element.

4. The device of claim 3, in which the element is a stack of leaf springs.

5. The device of claim 1, in which the compression means include a housing plate engaging the shoe and loosely engaged by the device housing, spring means engaging the housing plate, a cap engaging the spring means, and belts securing the cap to the housing.

6. The device of claim 1, in whichthe housing is secured to the movable member and the cam assembly is secured to the fixed member.

7. The device of claim 1, in which the bars of the cam assembly are connected at one end of the assembly and are elewhere spaced apart and one of the bars projects beyond its connection to the other bars and its projecting end is secured to the second member.

8. In a railway car, the combination with a car body, an underframe, and a rigid draft and bufiing column of substantially the same length as the car body and having couplers at its ends, the column being mounted on the underframe for longitudinal movement by forces applied to the couplers in a direction lengthwise of the column, of means for braking the movement of the column in either direction from a central position comprising a housing secured rigidly to the column, a cam assembly secured to the underframe and extending through the housing, the assembly included parallel bars extending horizontally and connected in spaced relation, one bar of the assembly having surfaces at one side of the assembly extending lengthwise of the bar and diverging in a direction away from the assembly, a friction plate extending transversely between and in contact with each two adjacent bars, a pair of spaced stops on the housing at each end of each plate, the ends of each plate lying between a pair of the stops and the width of each plate being less than the distance between the stops of the pairs associated with the plate to provide a limited freedom of movement of the plate in the direction of its width between the stops, a shoe engaging the outer bar of the assembly and movable by the housing along the diverging surfaces, and means on the housing acting through the shoe to compress the bars and plates, when the shoe is on one of the surfaces.

9. The combination of claim 8, in which the underframe includes a center filler casting and the cam assembly is connected at one end to the casting.

10. The combination of claim 8, in which the bars of the cam assembly are connected at one end of the assembly and are elsewhere spaced apart and one of the bars projects beyond its connection to the other bars and its projecting end is secured to the underframe.

11. The combination of claim 8, in which the widths of the plates and the spacings between the stops associated with respective plates are varied to give each plate a limited freedom of movement differing from that of each of the other plates.

12. The combination of claim 8, in which the resilient means include a damped compression element.

13. The device of claim 12, in which the element is a stack of leaf springs.

14. The combination of claim 8, in which the compression means include a housing plate engaging the shoe, a cap secured to the housing, and spring means between the housing plate and cap.

References Cited in the file of this patent UNITED STATES PATENTS 2,775,353 Tillou Dec. 25, 1956

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