US 2656182 A
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Oct. 20, 1953 D. wlLLls'oN cUsHIoNING DEVICE 2 Sheets-Sheet 1 Filed June 23, 1951 1 INVENTOR.
DONALD W/LL/so/v .BY @y @a ATTORNEY CUSHIONING DEVICE Filed June 23, 1951 2 Sheets-Sheet 2 INVENTOR. Do/VALD la//LL/so/v ATTRNEY Patented Oct. 20, l`1953 CUSHIONING DEVICE Donald Willison, Maple Heights, Ohio, assignor to National Malleable and Steel Castings. Company, Cleveland, Ohio, a corporation of Ohio Application June 23, 1951, Serial No. 233,139
13 claims. l
, This invention relates to cushioning mechanism for industrial or mine cars and more particularly to a. resilient pad for use in such a mechanism.
4In the past the usual mine car cushioning mechanism or draft gear, as it is4 generally called, comprised a simple helical spring. However, with the advent of larger mine cars the cushioning capacity of the draft gears hasV had to be correspondingly increased. Helical springs of sufficient capacity to cushion properly the larger carsv would have to be greatly increased in size and would require a larger pocket size in the car, thereby decreasing the, load-carrying space in the latter..` Moreoven, Ycorrosion conditions areA extremely bad in` most mines and the life of steel springs, isA relatively short. Y vI" have devised a cushioning pad which, when assembled with a series of similar pads, provides a, simple, compact and durable cushioning mechanism vhaving cushioning capacity several times that of a coil spring type of draft gear for use in a draft gear pocket of given size in industrial or mine cars. This pad therefore permits holding the pocket size in the car to a minimum, yet provides a gear which has adequate cushioning ca` pacity to. protect the largest size mine cars now being constructed.r The pad `comprises a metallic plate to a side of which is bonded 'ai ring-like rubberv cushion of novel construction. The pad has a central opening therethrough to receive the tail bolt or similar member of the draftA rigging of a car to en- -able operation of the car through a rotary dump while coupled to adjacent cars.
Accordingly, it is an object of my invention to provide a new and improvedv resilientv pad' of high cushioning capacity made of rubber or similar material bonded to a metallic plate.
More' specifically, it is an object of my invention to provide a resilient pad of a high cushioning capacity for use in a cushioning mechanism for industrial' or mine cars, comprising afmetallic plate and a.' rubber cushion of ring-like shape bonded: tothe plate.
Other objects and advantages of my invention will be apparent from the following description taken in conjunction with the drawings in which:
Fig. ,li is a plan view of a cushioning pad embodying. my invention.
Fig. 2 is a sectional view taken along line 2-2y of Fig. 1.
Fig..3 is a sectional view taken along line 3-3 of' Fig. 1.
Fig. 4 is. a graph illustrating the Acompression characteristics of a single pad embodying my inventionl and of a group of pads. f
Fig. 5 is a plan view, partly in section of a draft gear made` up of a group of pads of the type shown in Fig. 1.
Fig. 6-is an elevational view, partly in section, of the arrangement shown in Fig. 5.
Referring particularly to Figs. 1, 2 and 3, it will be seen that my cushioning pad comprises a thin metallic plate I to the opposite sides of which a ring-like rubber cushion I2 isbonded or otherwise secured. Plate I0 is rectangular in shape and of such dimensions as to be accommodated in the majority of conventional draft gear pocket constructions in industrial or mine cars. A central opening I4 is provided in plate I0 for receiving the usual tail bolt i6 (Figs. 5 and 6) used for connecting the coupler to the cushioning mechanism of the car to enable operation of the car through a rotary dump while coupled to adjacent cars. As best seen in Fig. 1, rubber cushion I2v is formed with its inner peripheral edge I 'I concentric about opening I4, while portions of the outer peripheral edges are also concentric about vthe opening as at I8 on the wider portions 20 of the pad. However, the outer peripheral edges ofthe narrower portions 22 are straight as 'at 24. Thus it will be seen that the cushion comprises apair of circular end portions which are joined to flattened side portions, the circular end portions being of greater width as measured in a direction radially'of the cushion than the average width of the side portions.
This configuration of the rubber cushion has been particularly devisedv for use in a draft gear pocket which is rectangular in transverse section with the dimensions thereof in the transverse direction being greater than that in the vertical direction. Moreover, it utilizes to a maximum the cushioning properties of the rubber per unit volume thereof.
The bond between the rubber and the plate prevents now ofthe base portion of theA cushion outwardly along the surface of the plate during compression of the rubber. This restriction of the flow of the rubber is highly important in determining the cushioning properties of the pad. 'Ihe bond stress is greatest along the peripheral edges of the cushion and in order to protect the bond it is important that the inner and outer sides of the rubber be sloped gradually around the entire cushion from the surface of the plate to the top or ridge of the cushion. This causes the rubber tofold or crease during compression of the pad substantially along a line spaced a sucient distance back from the peripheral edges of the cushion to assure protection of the bond.'
Without the gradual sloping of the rubber the crease during compression of the pad will occur at or very close to the peripheral edges of the cushion and will thereby cause a high bond stress at the edges, which Will result in rapid failure of the bond under repeated shock loadings. The feature of gradually sloping the sides of the rubber cushion to the ridge thereof has been disclosed in the copending application of Donald Willison and Hubert L. Spence, Serial No. 138,614, filed January 14, 1950.
I have found from lengthy endurance tests that the slope of the sides of the cushion should be less than about 30 degrees, but preferably no greater than about 23 degrees when the pads are subjected to repeated loadings which compress the rubber to about 45 per cent compression (pads compressed until rubber thickness equals 100 per cent minus 45 per cent, or 55 per cent of the thickness as measured at the crest of the ridge when the pad is under no load).
While the slope of 23 degrees is applied on the sides of the wider portions 20, it cannot be maintained on the sides of the narrower portions 22 because of the dimensional limitations of plate I0. Thus, if the sides of portions 22 were sloped at an angle of 23 degrees to the plate, the thickness of the rubber at the crest of these sections Would be considerably less than the thickness at the crest of wider portions 20. This would result in portions 20 carrying the bulk of the compressive load applied to the pad since portions 22 would be inactive in resisting the load until portions 20 had been compressed a substantial amount. Consequently, the load-carrying ability of the pad would be materially decreased, because the compression of portions 20 would determine the size of the load.
I have found that by forming the sides of the narrower portions 22 at a somewhat steeper slope than 23 degrees, 32 degrees for instance, and also holding the thickness of the rubber at the ridge thereof to a lesser dimension than that at the ridge of wider portions 20, the bond between the rubber and the plate will not be injured during compression of the pad. With the cushion thus formed, the narrower portions thereof are compressed only to about 38 per cent compression while the wider portions 20 are compressed 45 per cent. Thus, .while the steeper slope of 32 degrees on portions 22 would not provide satisfactory protection of the bond against the high bond stresses which would be set up if the rubber were compressed to about 45 per cent, these portions are now compressed only to about 38 per cent compression while the wider portions are being compressed to about 45 per cent. In this manner the bond stress which is induced along the peripheral edges of portions 20 and 22 is about the same and a cushioning pad of high durability as well as high cushioning capacity has been obtained.
It will be appreciated that in certain cases the relative length and width of plate l may be different from that shown, in order to fit the draft gear pocket in the car. Thus, in certain instances the cushion may be somewhat more elongated in appearance than shown, while in other cases it may approach the shape of a true ring. In either event, the slope of the sides of the narrower portions of the cushion should be such that the thickness of the rubber at the crest of the ridge is somewhat less than that at the crest of the ridge of the wider portions. This will assure that the narrower portions of the cushion which have the more steeply sloped sides will be compressed to a lesser degree than the wider portions when the latter have been compressed to about 45 per cent, thereby protecting the bond between the rubber and the plate.
The pad is provided with integral dowel means 30 and corresponding openings 32 for interlocking engagement with the recess and dowel of an adjacent pad to maintain a series of pads in alignment, as shown in Figs. 5 and 6. Preferably the dowel is formed at the crest of the ridge of the cushion, and one dowel and one recess are formed on each cushion with the dowel on one cushion disposed directly opposite the recess in the cushion on the other side of the plate. 'I'he dowels fit snugly in the recesses so that as the pads are compressed the dowels deflect in unison with the cushion bodies, thereby avoiding any abrasion of the rubber. This dowel construction has also been disclosed in the aforementioned application of Donald Willison and Hubert L. Spence.
In Figs. 5 and 6 there is shown a typical application of a series of pads to a conventional mine car draft rigging. The pads are arranged face-to-Iace with dowels 30 extending into recesses 32. The end pads 34 have a rubber cushion on one side only so that there is rubber-to-rubber contact throughout the entire group of pads. Followers 36 are interposed between the plates 38 of end pads 34 and front and rear stops 40 and 42, respectively, of the draft gear pocket. Plate 38 may be formed of thinner gage metal than plate l0, since it is subjected to a smaller stretching force by the single cushionA bonded thereto. The coupler shank 44 is operatively connected to the rigging by the tail bolt I6 to enable rotation of the coupler about its longitudinal axis with respect to the car. This permits revolving the car to an upside down position in a rotary dump while the car remains coupled to adjacent cars of a train. The tail bolt extends through central openings in followers 36 and through openings I4 in the pads and is formed at its forward end with a head portion 46 having shouldered engagement with front follower, as at 48. The coupler shank is formed with a bifurcated end portion 52 which is pivotally connected to head 46 by a vertical pin 54. The tail bolt is secured to the unit by a nutl 56 which is locked in place by means of auxiliary bolt and nut means 58. A transverse plate 60 secured to the car frame underlies the pads and followers to support the same.
The pads are preferably placed under an initial compression of about 5,000 pounds and. this is effected by adjusting nut 56 until the desired load has been applied. It will be seen in Fig. 5 that the pads are shown in full contact with adjacent pads. This results from the initial load applied to the pads which takes up the clearance which would exist between opposing ridges of portions 22 of the cushions if the pads Were uncompressed.
While it will be seen in Fig. 6 that the height of the pocket in the car is such as to allow the use of a pad of greater height than has been illustrated, in other car constructions the height of the pocket limits the dimension of the pad to that as shown in the drawings.
It willbe understood that more or less pads than have been illustrated in Figs. 5 and 6 may be used to form the cushioning mechanism, depending on the cushioning capacity required. A typical arrangement using ve pads (four monarca whole: pads having double: cushions; and: two single. cushionzendpadsir hasa-dynamicacushioncapacity of about 4,000 foot-pounds; which is` several: times the capacity' of: a. helicaf spring ior'use inY the, same pocketl size.
In. Fig.y iv is shown a.. graph: of the' load-travel characteristics of a; single cushioning pad and ofv a group of, pads. The; single pad andl the group of pads have been initially' subjected to af loadv of about 5,900 pounds; which corresponds to ther condition of theA pads when applied tothe draft rigging of a cari.. The top orf compression curvef ini each instance: illustrates the`- variation of travel with compressivel lbadl as the latter is slowly applied to the pads.. The releaseportion of the/curve: represents the loadatravel characteristicsasthe loadis gradually withdrawn.. The area between the twov curves represents energy absorbed' by the: rubber.. This absorptionisv approximately ieper cent of the total workv applied to the pads and.' serves to decrease theyrecoil; between-two cars' as they come together for coupling; It will be. noted that the curve for thej group of pads is considerably extended in the horizontal directionl as compared with that for the single pad, showing` the added travel' which isi obtained, for a given load.
In a cushioningv mechanism or draft gear made up of my cushioning padsA therey are nolmetallic stops to limit they amount of `compression or travel'v of the gear. Therefore, under blows of unusual severity the rubber in portions 2t#` of thepads may bey compressed more than 45 per cent and in portions 22 may exceed the 38 per cent value; IV have referred to these compression percentages andslope anglesk to illustrate my discovery that for a given degree of durability or service life there is `a certain approximate relation` between the slope of the rubber periphery and' the amount of allowable compression.v I have maintainedY this relationship throughout the different portions of my pad so that the bond stress at the peripheral edges of the cushion is substantially of the same value and a pad of maximum shock cushioning capacity and durability is produced.
It will be seen that I have provided a cushioning pad which is simple and yet durable, and when a group of such pads is arranged in the form of a cushioning mechanism a compact unit results which very adequately cushions the shocks incident to the service conditions to which it is subjected.
The terms and expressions which I have employed are used as terms of description and not of limitation, and I have no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.
l. A cushioning pad for a shock cushioning mechanism, comprising a plate having a rubber cushion secured to a side thereof, said plate having a central opening therethrough, said cushion being ring-like in shape and having its inner and outer sides sloped gradually upwardly from the surface of said plate, the sides of certain portions of said cushions being more steeply sloped than the adjacent sides, and the crest of said more steeply sloped portions being disposed at a lesser height above said plate than the crest of the adjacent portions. v
2. A cushioning pad for a shock cushioning 6, mechanism; comprising: a. plateA havingn a rubber cushion secured;- toy a side thereof, said cushion being ring-like` in shape and: having portions which are of lesser width than adjacent' portions, the sidesv of said' cushion` being sloped gradually upwardly fromthe surface of' said' plate, the thickness4 of' said cushion at the crest ofsaid portionsioflesser widthlbeing lessthan' thefthickness at the crest of adjacent portions;
3; A cushioning pad for a shock cushioning mechanism, comprising a plate having a cushion inf the form of a ring-like ridge of rubber bonded toi a. sidethereof', said cushion comprising a pair of circular end portions and a pair of substantially straight side portions, the sides of said circular portions being sloped gradually from theV surface of said' platev tol the crestA of' said ridge, the sides of said side portions having a steeper slope than the sides of said circular portions and the lcrest of` the ridge of" said side por'- tions being'disposed at' a lesser height abovesaifd plate-than the crestor' the ridge of said circular portions.
4'. A` cushioning pad for a shock cushioning mechanism, comprising a plate having a rubber cushion bondedto a side thereof, said cushion being ring-like in shape and having a pair of oppositely disposedl end portions which are of greaterwidth than the adjacent pair' of' oppositely disposed side portions, the sides of said first-named portions being sloped gradually upwardly from the surface of' said plate, the sides of said second-named portions-being more steeply slopedthan the sides of saidffi'rst-named portions and the thickness of said second-named portions being less than the thickness of said first-named portions.
5. A cushioning pad as specified in claim 4, having dowel and recess means for maintaining said pad in alignment with a similar pad when assembled therewith.
6. A cushioning paid for a shock cushioning mechanism, comprising a plate having a rubber cushion secured to a-side thereof, said cushion being ring-like in shape and having portions which are of greater width than adjacent portions, the sides of said portions of greater width being sloped upwardly from the surface of said plate at an angle no greater than about 23 degrees to permit repeated compression of said pad an amount equal to about 45 per cent of the maximum thickness of the rubber without bond failure, the sides of the narrower portions of said cushion being sloped at an angle of about 32 degrees and the maximum thickness of the rubber of said narrow portions being slightly less than that of said wider portions.
7. A cushioning pad for a shock cushioning mechanism, comprising a plate having a cushion in the form of a ring-like ridge of rubber bonded to a side thereof, portions of said cushion having the crest of said ridge disposed at a lesser height above the surface of said plate than adjacent portions, said first-named portions being of lesser width than the adjacent portions, the sides of said first-named portions being sloped at an angle of about 32 degrees and the sides of said adjacent portions being sloped at an angle of no greater than about 23 degrees.
8. A cushioning pad for a vshock cushioning mechanism, comprising a rectangular plate member having a circular central opening therethrough, a rubber cushion bonded to a side of said plate, said cushion being in the form of a ring-like ridge having its inner periphery concentric about said opening, portions of the outer periphery of said cushion being concentric about said opening and other portions of said outer periphery being straight, the sides of said rstnamed portions being sloped at an angle of no greater than about 23 degrees to said plate to permit repeated compression of said pad an amount equal to about 45 per cent of the maximum thickness of the rubber Without bond failure, the sides of said other portions being sloped at an angle of about 32 degrees and the maximum thickness of the rubber of said other portions being slightly less than that of said firstnamed portions.
9. A cushioning pad for shock cushioning mechanism, comprising a metallic plate to the opposite sides of which a rubber cushion is bonded, said cushion being in the form of a ring-like ridge and comprising a pair of circular end portions joined to substantially straight side portions, said circular portions being vvider than said side portions and having the sides thereof sloped at an angle of no greater than about 30 degrees to said plate, said side portions having the sides thereof sloped at an angle of no greater than about 32 degrees and the thickness of the cushion at the crest of said side portions being less than at the crest of said circular portions.
10. A cushioning pad as specified in claim 9, having an integral projection on said ridge and a corresponding opening spaced from said projection, said projection and opening being adapted to interlock with the opening and projection of an adjacent similar pad to maintain a group of pads in alignment.
11. A shock cushioning mechanism comprising a group of cushioning pads arranged in face-toface engagement, certain of said pads comprising a plate having a rubber cushion secured to opposite sides thereof, the end pads of said group comprising a plate having a single rubber cushion secured to a side thereof, each of said cushions comprising a ring-like ridge having certain portions of greater thickness than adjacent portions, said portions of greater thickness having the sides thereof sloped at an angle of no greater than about 30 degrees to the plate, said adjacent portions having the sides thereof sloped at an angle of no greater than about 32 degrees.
12. A shock cushioning mechanism comprising a group of cushioning pads arranged in face-toface engagement, certain of said pads comprising a plate having a rubber cushion secured to opposite sides thereof, the end pads of said group comprising a plate having a single rubber cushion secured to one side thereof, each of said cushions being ring-like in shape and having portions which are of lesser Width than adjacent portions, the sides of said cushion being sloped gradually upwardly from the surface of said plate, the thickness of said cushion at the crest of said portions of lesser Width being less than the thickness at the crest of said adjacent portions.
13. A cushioning pad for a shock cushioning mechanism, comprising a plate having a rubber cushion secured to a side thereof, said cushion comprising a ridge having a side sloped gradually upwardly from the surface of said plate, certain portions of said side of said ridge being more steeply sloped than the adjacent portions, and the thickness at the crest of said ridge at said more steeply sloped portions being lesser than the thickness at the crest of said adjacent portions.
References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,126,707 Schmidt Aug. 16, 1938 2,260,532 Lindeman Oct. 28, 1941 2,328,877 Gallagher Sept. 7, 1943 2,553,636 Dath May 22, 1951