US2814392A

US2814392A - High capacity shock absorber for freight cars

Info

Publication number: US2814392A
Application number: US388787A
Authority: US
Inventors: David S Campbell
Original assignee: Cardwell Westinghouse Co
Current assignee: Cardwell Westinghouse Co
Priority date: 1953-10-28
Filing date: 1953-10-28
Publication date: 1957-11-26
Anticipated expiration: 1974-11-26
Also published as: BE531748A

Description

5 SheetsFSheet 1 QN IIIII Nov. 26, 1957 D. s. CAMPBELL HIGH CAPACITY SHOCK ABSORBER FOR FREIGHT CARS Filed Oct. 28, 1953 5 Sheets-Sheet 2 D. s. CAMPBELL HIGH CAPACITY SHOCK ABSORBER FOR FREIGHT CARS Nov. 26, 1957 Filed oct. 2a, 1953 Nov. 26, 1957 D. s. CAMPBELL HIGH CAPACITY SHOCK ABSORBER FOR FREIGHT CARS Filed Oct. 28. 1953 5 Sheets-Sheet 5 d y H 2 2 2 w f .a n l. J 0 y 4 W 9685 Nov. 26, 1957 D. s. CAMPBELL 2,814,392

HIGH CAPACITY SHOCK ABSORBER FOR FREIGHT CARS Filed UCL. 28, 1953 5 Sheets-Sheet 4 amg/ffl l JNVENTOA BY m, @Mw/Maman Nov. 26, 1957 n. s. CAMPBELL HIGH CAPACITY SHOCK ABSORBEIR FOR FREIGHT CARS 5 Sheets-Sheet 5 Filed Oct. 28, 1953 United States Patent HIGH CAPACITY SHCK ABSORBER FOR FREIGHT CARS David S. Campbell, Glen Ellyn, Ill., assigner to Cardwell Westinghouse Company, a corporation of Delaware Application October 28, 1953, Serial No. 388,787

3 Claims. (Cl. 213-33) This invention relates to shock absorbers for railroad cars, and has for its principal object to increase the capacity of the absorber and the travel of the coupler head in buff while retaining the presently required draft gear pocket and draft gear attachments together with low reaction to the car.

Generally speaking, this is accomplished by offsetting the front follower and the draft gear housing to let the coupler head move further from the striking plate in full release than is possible with existing devices, and increasing the energy absorbing and dissipating means through increased travel thereby permitted, and thus maintaining the desired low reaction forces.

The existing draft gears in service were for the most part designed and built to properly cushion the bufling shocks of SO-ton cars moving at a speed of four miles an hour, whereas present practice in freight yards is to switch cars at eight to ten miles per hour. That increase in speed or velocity of the cars enormously increases the energy to be absorbed in buff, for the energy of the buing shock is a function of the square of the velocity.

It is thus apparent that existing cars are being so handled as to make the bufling shocks far beyond the capacity of the draft gears to handle, and neither the equipment nor the lading is adequately protected. Two million such cars present a major problem to all concemed.

The function of a draft gear is to absorb and dissipate the energy of shocks received by the coupler. With increased travel, that energy can be absorbed with proportionately less reaction to the car-without exceeding the column strength of the coupler shank or the elastic limit of that shank.

Further objects and advantages of the invention will appear as the description is read in connection with the accompanying drawings, in which Fig. 1 is a horizontal section through familiar parts of a freight car showing the draft gear pocket and the draft gear attaching devices, as specified by the Association of American Railroads;

Fig. 2 is a vertical section through the same on a smaller scale;

Fig. 3 is a horizontal section through the same familiar parts of a freight car with the coupler and draft gear attachments shifted forwardly in accordance with this invention;

Fig. 4 is a vertical section of the saine on a reduced scale;

Fig. 5 is an enlarged horizontal section through a draft gear of increased capacity and travel made according to this invention, the draft gear being shown in full release;

Fig. 6 is a similar section showing the draft gear compressed;

Fig. 7 is a vertical section along the medial line of the draft gear in full release;

Fig. 8 is a perspective view of the draft gear and the front follower;

Fig. 9 is a perspective view of the draft gear housing;

2,814,392 Patented Nov. 26, 1957 ICC Fig. 10 is a perspective view of the friction plates and wedge shoes; and

Fig. l1 is a perspective view of the plunger or central wedge member.

But these drawings and the corresponding description are for the purpose of illustrative disclosure only, and are not intended to impose unnecessary limitations on the claims.

ln Figs. l and 2, there is shown center sills 10, front and rear draft gear lugs 11 and 12, vertical yoke 13 connected to a coupler shank 14 by a draft key 15 in the positions they assume in full release with a coupler horn 16 spaced from a striking plate 17 and a front follower 18 within the yoke 13 and against the front draft lugs 11, all substantially in accord with the specifications of the Association of American Railroad Operations and Maintenance Department Mechanical Division M-901-4l, Approved Draft Gears for Freight Service.

The sills ll) and the yoke 13 are broken away in the mid portion of the draft gear pocket in Fig. l to shorten the drawing, and the draft gear is omitted in that figure.

The coupler carrier iron is shown at 19, and the draft gear carrier iron at 20.

ln Figs. 3 and 4, the front follower 18 is shown provided with a projection or extension 21, which may be a plate, for example, V2" thick and narrow enough to lit within the arms of the yoke 13 and welded to the follower at 22.

As illustrated in Figs. 3 and 4, the effect of that projection is to shift the coupler horn 16, the key 15, and yoke 13 forwardly or to the left l/z, giving 31/2" clearance between the coupler horn 16 and the striking plate 17 instead of the 3" clearance in the specified standard illustrated in Figs. 1 and 2. That affords clearance of 3%" of travel for the coupler horn 16, leaving 1A" clearance from the striking plate 17 on full compression, and that makes it possible to greatly increase the capacity of the draft gear without increasing the reaction forces transmitted through the coupler shank to the gear and without exceeding the column strength of the coupler shank 14.

With the longer stroke and the consequent longer travel of the energy absorbing and dissipating devices in the draft gear, increased capacity can be had while retaining reaction forces low enough to be well Within the strength of the coupler shank.

The draft gear herein illustrated, particularly in Figs. 5S, is similar to the well known Westinghouse draft gear (Car Builders Cyclopedia, 1946, p. 942), but with greatly increased capacity.

The draft gear housing (Figs. 8 and 9) generally indicated by 24 is an oblong, rectangular, hollow steel casting having its rear or inner end offset at 25 an amount corresponding to the projection 21 on the front follower 18.

In the rear of the housing 24, there are in this instance three

helical springs

26, 27, and 28 adapted to be compressed between the rear wall 29 of the housing and a spring seat and follower 30. Instead of three springs, two double coils in parallel will afford ample spring capacity.

In the front portion of the housing 24 and projecting through the open front end is a friction mechanism including groups of intercalated plates of which 5, 6, and 7 are stationary and 8 and 9 are movable.

Between the stationary plates 7 of each group there are wedge shoes 32 having wedge surfaces 34 on a central plunger 35. The shoes 32 also have inclined surfaces 36 cooperating with like surfaces 37 and a projection 38, here shown as a part of the spring seat and follower 30, but which may be separate from them.

The central plunger and the projection 38 have opposed spring seats 39 and 40 for a coil spring 41, which constantly urges the plunger 35 toward released position.

The inclined surfaces 36 and 37 are on the angle of repose of the material, and are inclined mainly to prevent sticking, which would likely occur if the surfaces were at right angles to the axis of the car.

The capacity of the draft gear can be made whatever is required mainly by the angle of the

wedge surfaces

33 and 34 on the plunger 35 and the wedge shoes 32, and the number of intercalated friction plates in the groups.

As illustrated in Figs. and 6, the plunger 35 takes the thrust of the drawbar shank 14 through the front follower 18.

Operation In operation, the bufting shock is transmitted to the plunger 35, forcing it to the right in Figs. 5, 6, and 7, causing it to act through the wedge shoes 32 and the projection 38 to transmit the travel to the spring seat 39 on the follower 30 and compress the

springs

26, 27, and 28. These parts will furnish sufficient cushioning for light bung shocks. After suitable travel, however, on the order of 1/2", the follower 18 will come against the outer ends of the movable plates 9, introducing energy absorbing friction between the movable plates 9 and the stationary plates 6 and 7, which have been pressed together by the action of the wedge shoes 32. With additional travel, the follower 18 will come against the outer ends of the movable plates 8, adding friction between those plates and the

stationary plates

5 and 6. Meanwhile, the pressure between the adjacent surfaces of the intercalated plates has been enormously increased by the action of the wedge shoes 32. The energy absorption and dissipation through friction and compression of the springs continues until the gear is closed, if necessary, as indicated in Fig. 6.

The nominal capacity of a freight draft gear for use in the standard draft gear pocket and draft gear attachments illustrated in Figs. l and 2 is on the order of 21,000 foot pounds, approximately one-half of which may be in intercalated plates and the remainder in the springs, substantially as appears in the Westinghouse draft gear (Car Builders Cyclopedia, 1946, p. 942).

With the additional travel, the addition of intercalated plates, the appropriate angles on the

surfaces

33 and 34 and the

appropriate springs

26, 27, and 28, a great increase in capacity over the nominal is readily accomplished, and the absorption and dissipation of the energy of shocks of freight cars having increased velocity can be taken care of in 3% of travel with a minimum reaction.

The 5" X 7 coupler shank customarily used in 50-ton cars has a column strength of 500,000 pounds, and with a draft gear such as illustrated and described herein capacity necessary to absorb the high buing shocks is had with low reaction well within the ability of the coupler shank to stand.

In Fig. 5, it will be seen that the movable plates 8 are considerably shorter than the movable plates 9. That is to protect the former in the instance where the buing shock comes when the car is on a curve and the drawbar is at an angle to the center line of the car. A clearance of on the order of l", as illustrated in Fig. 5, is sufficient to prevent distortion of the plates 8 by such angular blows.

Assembly To facilitate assembling, the housing 24 is provided with openings 44. and the spring seat and follower 30 are provided with an opening 45 into which assembly pins may be inserted upon suitable compression of the

springs

26, 27, and 28, which will give ample clearance to assemble the friction devices; first, the stationary plates, then the wedge shoes, then the spring 41 and the central plunger 35, the latter being first rotated toward the horizontal position to enter the open front of the housing 24, and then brought to vertical position in order to put the arms 42 in the position they appear in Fig. 7. Finally, the movable plates 8 and 9 are inserted.

The stationary plates 5 are held by

vertical ribs

46 and 47, and the stationary plates 6 and 7 by horizontal ribs 48 and 49 above and below in the housing.

The central thrust member 35 has arms 42 which cooperate with the inner sides of the horizontal ribs 48.

In order to shorten the gear temporarily for inserting it into the draft gear pocket, the arms 42 are provided with projections 49. After a few normal operations of the gear, those projections 49 will cut into the ribs 48 and allow full release of the gear between the lugs 11 and 12.

I claim:

l. In a railway freight car of the type having a coupler, a yoke, and a center sill having spaced front and rear lugs defining a draft gear pocket, which pocket conventionally has associated with it a friction draft gear of a given capacity that closes after a given travel with a given reaction force on the center sill of the car; a draft gear arrangement mounted in said pocket in association with said yoke and coupler in place of said conventional gear and in comparison therewith, having a substantially in* creased travel before closure during which increased travel substantially increased energy absorption occurs to provide a substantially increased gear capacity without the development of forces in excess of the column strength of the coupler, said arrangement including a draft gear housing having an open front end and a forwardly or inwardly offset rear end center portion accommodating a forward displacement of said yoke, cushioning means reacting against the offset rear end of said housing, an energy absorbing friction mechanism in the housing in tandem relation with said cushioning means, an intermediate follower located between said cushioning means and said friction mechanism and movable longitudinally of the housing, a front follower bearing on one side against the front lugs when the gear is under no load and bearing on its other side against said friction mechanism, said friction mechanism including a front wedge reacting against the front follower, a rear wedge longitudinally spaced therefrom and movable with said intermediate follower, laterally spaced wedge shoes positioned between and coacting with said front and rear wedges and having outwardly facing friction surfaces, inwardly facing friction surfaces in said housing and engaging said outwardly facing friction surfaces of the wedge shoes, said friction mechanism being actuated by relative movement between said front follower and said housing to translate at least a portion of the longitudinal forces applied to the gear into lateral forces to develop friction at said opposed friction surfaces, said housing having an abutment surface against which said front follower closes to limit actuation of said friction mechanism, the distance between said front fol lower and said abutment surface when the gear is under no load being equal to the sum of said given travel and the amount by which the rear end is offset, said follower having a forward extension cngageablc with the rear end of said coupler to displace the same forwardly an amount equal to that of the rear end offset of the housing.

2. The invention of claim l wherein a group of intercalated stationary and movable friction plates disposed within the housing at each side thereof provide said inwardly facing friction surfaces, with the movable plates of said groups projecting longitudinally outwardly of said abutment surface for engagement with said front follower during a portion of the relative movement between said front follower and said housing.

3. The invention of claim l wherein a group of intercalated stationary and movable friction plates disposed within the housing at each side thereof provide said inwardly facing friction surfaces, with the movable plates of said groups projecting longitudinally outwardly of said References Cited in the le of this patent UNITED STATES PATENTS OConnor Dec. 22, 1925 Woernley Jan. 13, 1931 Waldin Feb. 9, 1932 Wllison Apr. 2l, 1953 Willison et al. June 2, 1953