US3390787A - Railway car shock protection device - Google Patents

Description

July 2 1968 v. J. GRUMBLATT 3,390,787-y RAILWAY CAvR SHOCK PROTECTION DEVICE Filed Dec. 23, 1965 vvv-vvv du 7i www United States Patent C ABSTRACT F THE DISCLOSURE At one end of a railway car sill, the car sill end of a draft gear is connected to a first sliding sill preloaded or biased outward against a first stop on the car sill by a spring element, preferably an elastomeric sandwich, connected between the sliding sill and a second stop on the car sill. The spring element supplements the draft gear by cushioning inward (buff) but not outward (draft) forces. In a preferred form, there is a second sliding sill at the other end of the car preloaded or biased outward against the second stop by an elastomeric sandwich spring element connected between the sliding sills.

The present invention cushions shocks in railway cars by elastomeric cushioning devices on a sliding sill between the draft gears. The elastomeric mountings act in series with the draft gears under both impact and squeeze loads. The construction may be applied to existing cars as well as new constructions.

In the drawing, FIG. 1 is a diagrammatic section side elevation of a preferred form of shock cushioning system, FIG. 2 is a side elevation of the sill construction partly broken away, FIG. 3 is a section on line 3-3 of FIG. 2, and FIG. 4 is a top plan view of the sill partly broken away.

In FIG. l, the car body 1 is shown supported on a frame having a center sill 2 extending the full length of the car. At opposite ends of the sill are draft gears 3 land 4 including the usual car coupler and some form of cushioning device. Draft gears are Well known and the details need not be illustrated. The draft gear 3 has a connection 5 to a beam 6 extending nearly the full length of the sill. The draft gear 4 has a connection 7 to 4a beam 8 likewise extending nearly the full length of the sill. Preferably, the beams are arranged one above the other. Between the beams 6 and 8 and connected to them are a plurality of elastomeric shear sandwich mountings each consisting of an upper plate 9 xed to the beam 6, a lower plate 10 fixed to the beam 8, and a body 11 of suitable elastomer sandwiched between and bonded to the plates 9 and 10. Relative longitudinal movement of the beams 6 and S stresses the elastomer in shear. The mountings are shown in FIG. 1 in the installed position where the beams 6 and 8 are confined between stops 12 and 13 fixed to the center sill 2, thereby placing the bodies 11 of elastomer under -a preload. Until the forces exceed the preload, the beams 6 and 8 remain against the stops 12 and 13.

In draft, the draft gears operate in their normal manner against the stops in the draft gear pocket and without any action on the sliding center sill. However, in buff, the draft gear is permitted to slide in the pocket against the force or reaction of one of the sliding sill beams, causing the shock mountings to deect in shear to 4absorb the impact. More specifically, one draft gear and one sliding sill beam move while the other gear and beam remains stationary. An impact from the other end of the car will cause that draft gear and the other sliding sill beam to move. The effect is the cush-ioning system plus one draft gear acting in series during impact.

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For example, when cars are connected by humping, the coupler of the moving car strikes the coupler of a stationary car with an energy depending upon the weight and speed of the moving car. The impact causes shock forces in both the moving and stationary cars. Assume that the car 1 is moving to the right and the coupler of its draft gear 4 strikes the mating coupler of a stationary car. If this impact force exceeds the preload, as is usually the case, the beam 6 along with the car continues to move to the right while the beam 8 is brought to a stop, deilecting the bodies of elastomer 1'1 in shear. The impact energy is absorbed by the deflection of the draft gear and of the bodies of elastomer 11 and the maximum resultant force will be encountered with a fully loaded car. Because of the large deflection permitted by the bodies of elastomer 11, the maximum force can be limited to approximately three times the combined weight of car 1 and lading. Total maximum deflection will consist of twelve inches motion of the bodies of elastomer 11 plus the regular draft gear deflection. By changing the characteristics of the bodies 0f elastomer 11, the maximum motion can be either greater or less than twelve inches.

Under some conditions, there is a squeezing force between the draft gears 3 and 4. For example, if the car 1 is the end car coupled to a stationary train through draft gear 4, the impact of a moving car striking the coupler of draft gear 3 will subject draft gears 3, 4 to a squeezing force. Under this squeezing force, the beam 8 will be held more or less stationary and the beam 6 will move to the right. To prevent damage to the mountings which have a predetermined energy capacity, the -beam-s 6 and 8 are provided with stops 14, 15 which limit the travel between the beams to the same amount used for impact cushioning of the moving car. During impact cushioning of the moving car, one draft gear and the mountings act in series. Under squeeze conditions, both draft gears act in series with the mountings.

To evaluate performance, a weight of 150,000 pounds was estimated for the car plus lading in a 50 ton box car. Calculated performance is based on assuming only 60% of the impact energy is to be absorbed by the cushioning system (the balance of the energy is absorbed in the draft gears and moving of the struck cars). The sliding beam arrangement offers protection for the car as well as the lading.

In operation, the standard draft gear is capable of 2.75 inches of travel and the elastomeric cushioning units can travel l2 inches. Stops 14, 15 should be used between beams to allow only l2 inches travel between them.

Protection offered is as follows:

Tolerances and misalignment between sliding 4beams and center sill have little effect on cushioning performance. The elastomeric parts can be 4of value in accommodating either one.

This arrangement makes use of draft gear friction and elastomer hysteresis to obtain damping. Additional energy dissipation may not be necessary. If there is a need for more friction damping, numerous methods of obtaining it Iare possible. One method is to allow approximately .06 clearance 'between the two sliding beams when assembled but not preloaded. This clearance will decrease as the mountings deflect in shear, due to the mountings having a tendency to foreshorten or decrease in thickness when deflecting in shear. This shortening or decrease in thickness may be about .50 inch. Thus, the .06 clearance free would decrease to zero and then place the elastomer in tension as shear strain increases. The tension holds the two sliding beams together with a force equal to the tension in the elastomer. For low impacts, this friction willbe low-for high impacts, friction force will be high.

Friction can be added also by locating wedge-shaped incline's on one member and similar surfaces, suitably located, on` another. Relativel motion then can apply compression strain to the mountings to obtain increasing friction forces.

FIGS. 2, 3 and 4 show the construction of the center `sill and of the mountings and beams mounted therein but are diagrammatic as to the draft gear.

The center sill comprises an inverted channel 16 with its open lower end closed by a cover plate 17. The center sill 16 is of standard construction. Within the center sill are two I- beams 18 and 19 corresponding respecf tively to the beams 6 and 8. The flanges 20, 21 of the I-beams have a sliding clearance with the sides of the center sill. Between the webs 22, 23 of the I-beams are mounted 4a plurality of sandwich mountings 24 evenly spaced along the I-beams to aid in providing stability. For a 50 ton car, there are substantially twelve of these sandwich mountings, each of a size determined by engineering practice for acceptable strain and stress levels.

Such mountings may be each approximately twentyy inches long, six inches high and six inches wide. Each mounting comprises an upper plate 25, a lower plate 26, and a body 27 of suitable elast-omer sandwiched between and bonded to the plates. The plates 25, 26 are suitably bolted to the associated webs 22, 23. As installed, there is a slight clearance between the surfaces 28, 29 of the flanges 20, 21. As the shear sandwiches are deflected longitudinally, the elastomer tends to decrease in height and to bring the plates 25, 26 closer together. This is prevented by the abutting surfaces 28, 29 of the fianges and accordingly the elastomer is placed under tension holding the surfaces 28, 29 in friction contact. This tension increases as the shear strain increases, providing increasing friction. For low impacts, the friction will be low while for high impacts the friction will be high. Other expedients are available for increasing the friction, such as wedge-shaped surfaces.

In FIGS. 2 and 3, the draft gear and the connections between the draft gear and the I- beams 18 and 19 are diagrammatically shown. Draft gear 30 at the left end of FIG. 2 has socket connections 31 to a member 32 fixed to the I-beam 18. Draft gear 33 has similar socket connections 34 to member 35 fixed to the I-beam 19. The socket connections 31 and 34 are effective to transmit compression or tension stress to the I beams 18 and 19. Compression load applied between the draft gear 30, 33 can be used to position the members 32, 35 between stops 36 and thereby apply the desired preloadto the mountings.

Among the advantages of the system are lower cost than hydraulic shock absorbers, high energy capacity, less than 3g transmitted shock for a fully loaded car impacted at ten miles per hour, and ease of installation on the center sills of existing cars. For assembly, the beams 18, 19 and the associated mountings are inserted in the center sill 16 and the cover plate 17 then attached to the open lower end of the sill holding the beams in place.

What is claimed as new is:

1. A railway car having a center sill extending between one end and the other end of the car, a first longitudinal beam having one end at said one end of the car and extending slidably inward from said one end of the car, first draft gear means including a first car coupler and cushioning means, a force transmitting connection from the first draft gear means to said first beam, a second longitudinal beam having one end at said other end of the car and extending slidably inward from said other end of the car, second draft gear means including a second car coupler and cushioning means, a force transmitting connection from the second draft gear means to said second beam, first and second longitudinally spaced stops on the sill, the first stop being adjacent said one end of the car and the second stop being adjacent the said other end of the car, a stop on said first beam inward from and presented toward said first stop, a stop on the second beam inward from and presented toward the second stop, spring means in thrust relation between the first .and second beams exerting a force in the direction to slide the first and second beams out of the sill, -said spring means being initially stressed to a preload sufficient to hold the stop on the first beam against the first stop and the stop on the second beam against the secondkstop in the absence of other forces, and said spring means yielding under inward forces in excess of said preload applied to said first and second couplers to cushion said inward forces.

2. The railway car of claim 1 in which the sill is an inverted channel open -at the bottom and the beams are held in place by a bottom cover plate fixed to the channel.

3. The railway car of claim 1 in which the beams have stops limiting relative longitudinal movement of the beams under compression load applied between the couplers at opposite ends of the sill.

4. The railway car of claim 1 in which the spring means comprises elastomeric sandwich means having elastomer sandwiched between and anchored to spaced surfaces and stressed in shear by relative longitudinal movement between the surfaces, one of the surfaces being fixed to the first beam and the other surface being fixed to the second beam.

5. The railway car of claim 4 in which the beams have webs spaced from each other and the elastomer of the -shear sandwich means is between and anchored to the webs.

`6. The railway car of claim 4 in which the beams have opposed longitudinally extending friction surfaces in overlapping relationship presented toward and held in contact with each other by the decreasein thickness of the elastomer of the shear sandwich means when deflecting `in shear.

7. The railway car of claim 4 in which the shear sandwich means comprises several mountings between and distributed along the length of the beams and each mounting comprises spaced plates respectively anchored to one and the other beam and body of elastomer sandwiched between and bonded to the plates.

8. The railway car of claim 4 in which the shear sandwich means comprises the sole load transmitting connection between the beams.

9. The railway car of claim 4 in which the first and second beams have opposed longitudinally extending friction surfaces in overlapping relationship and presented toward and held in contact with each other by the decrease in thickness of the elastomer of the shear sandwich means when deliecting in shear.

10. The railway car of claim 4 in which the shear sandwich means comprises the sole load transmitting connection for inward forces from said yfirst and second beams.

- 11. A railway car having a center sill, first and second longitudinally extending beams longitudinally slidable in the sill, first and second longitudinally spaced stops on the sill and presented toward each other, a stop on the first beam presented toward the first stop on the sill, a stop on the second beam presented toward the second stop on the sill, the stops on the beams being between the stops on the sills and facing away from each other, spring means between the beams having elastomer sandwiched between and anchored to the beam-sI 5 6 and stressed in shear by relative longitudinal movement References Cited 0f the beams, the elastomer being initially stressed in shear to a predetermined preload holding the first and UNITED STATIZS PATENTS second stops on the beams respectively against the rst 1,027,323 5/1912 Damblno 213-8 and second 4stops on the sill until the forces exceed the 5 3,102,646 9/ 1963 Clejan 105-368 X preload, a draft gea-r, and a force transmitting connee- 3,178,035 4/ 1965 Peterson 213-8 tion from the draft gear to the first beam, whereby in 3,179,067 4/ 1965 Beck et al. 10S-368 draft the draft gear operates in its normal manner and 3,203,361 8/ 1965 Sharp 10S-368 in buff the first beam is moved inward relative to the 3,223,049 12/ 1965 Peterson 10S-392.5

second beam to deflect the elastomer in shear to add to 10 lthe cushioning effect of the draft gear alone. DRAYTON E. HOFFMAN, Primary Examiner.

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