US2956692A - Draft gear with supplemental resistance mechanism - Google Patents

Description

DRAFT GEAR WITH SUPPLEMENTAL RESISTANCE MECHANISM Filed June 4, 1958 Oct. 18, 1960 D. s. CAMPBELL 4 Sheets-Sheet 1 F I J 7 7 H W 3. 1. .wn 3 w. w 4 I) a l K fizz/ea Z02 Z M Z Z a Oct. 18, 1960 D. s. CAMPBELL 2,956,692

DRAFT GEAR wnu SUPPLEMENTAL RESISTANCE MECHANISM Filed June 4, 1958 4 Sheets-Sheet 2 Oct. 18, 1960 D. s. CAMPBELL DRAFT GEAR WITH SUPPLEMENTAL RESISTANCE MECHANISM Filed June 4, 1958 4 Sheets-Sheet 3 74 35 44 m m w. .m m

fizvezu ow DaudS C'anz vell w 6W c figyst l GEAR TRAVEL Oct. 18, 1960 DRAFT GEAR WITH D. S. CAMPBELL Filed June 4, 1958 4 cl Hydraulia I any 2 GEAR CLOSURE INCHES SUPPLEMENTAL RESISTANCE MECHANISM Sheets-Sheet 4 United States Patent DRAFT GEAR WITH SUPPLEMENTAL RESISTANCE MECHANISM David S. Campbell, Glen Ellyn, Ill., assignor to Cardwell Westinghouse Company, a corporation of Delaware Filed June 4, 1958, Ser. No. 739,934

13 Claims. (Cl. 213- 34) This invention relates to draft gears for railroad cars and has for its principal object the provision of separately acting intermediate followers for a draft gear arrangement that includes a casing having an open end receiving a main spring cushioning element that acts through an individually acting intermediate follower for yieldably setting up and releasing and resetting a friction mechanism of a type that includes a slidable friction plate arrangement that is disposed between and under lateral compression between the casing and a wedge-shaped main plunger, with a supplemental resistance mechanism acting through a separate intermediate follower to yieldably oppose movement of the friction plate arrangement during closure of the gear and provide a gear of high capacity in which the energy absorption progressively increases as the gear closes.

Another object is to provide a draft gear of the above type wherein the supplemental resistance mechanism is a velocity-responsive, variable-rate device providing increased resistance to closure when subjected to highspeed application of load.

Still another object is to provide a draft gear of the above type, the parts of which are constructed and arranged to permit of assembly of the entire gear from the open end of the casing.

Other objects and advantages will become apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same:

Fig. 1 is a reduced horizontal section through familiar parts of a railway freight car showing the draft gear mounted in a draft gear pocket in association with the coupler-yoke of the draft gear rigging;

Fig. 2 is an enlarged horizontal section through the draft gear of the present invention, with the gear being shown in full release position;

Fig. 3 is a view similar to that of Fig. 2 and showing the draft gear in closed position;

Fig. 4 is a vertical, sectional view through the draft gear showing the gear in full release;

Fig. 5 is a developed vertical cross-sectional view taken approximately on the line 5-5 of Fig. 2 and illustrating, in phantom, the movable friction plates of the friction mechanism;

Fig. 6 is a perspective view of the intermediate followers;

Fig. 7 is a capacity curve for the gear;

Fig. 8 is an enlarged horizontal section of an alternative form of draft gear according to the invention; and

Fig. 9 is a performance curve for the gear arrangement of Fig. 8.

For purposes of disclosure, in Fig. 1 the draft gear of the invention is shown mounted in a draft gear pocket in association with the familiar surroundings of center sills 20, front and rear draft gear lugs or stops 21 and 22, respectively, a vertical yoke 23 connected to 'a coupler shank 24 by a draft key 25, with a conventional front 'ice 2 follower 26 within the yoke 23 to abut against lugs 21.

The present draft gear, generally designated as 28, in: cludes a casing 29 having a rear chamber 30 for resilient cushioning mechanism generally designated as 31 and a front chamber 32 for a familiar type of friction-cushioning mechanism generally designated as 33, with the front chamber being in open communication with the reart chamber and having an opening 34 through the front end of the casing.

The draft gear casing 29 is an oblong, generally rectangularly shaped, hollow steel body having top, bottom and side walls designated, respectively, 35, 36 and 37 and interconnected by a transverse rear wall 38, with the portions of the top and bottom walls that define the rear chamber each being formed with a pair of laterally (see Fig. 5).

mechanism that is to be compressed against the portions of the rear wall 38 which overlie the rear lugs 22 so that the added resistance to closure of the gear that is provided by these supplemental units produces reaction forces in direct alignment with the rear lugs and no' added strain is imposed upon the casing of the gear either 1ongitudinally or laterally thereof.

Each of the supplemental resistance units in this form of the invention has a generally arcuate or kidney-shaped configuration and conforms generally to the contoursof' the auxiliary spring chambers and is shown as comprising, a longitudinally aligned stack of alternating rubber spring units 65 and spacer plates 66, with each rubber unit in cluding a mounting plate 67. The spacer plates 66 and mounting plates 67 areof a hollow pan construction to provide edge flanges 66F and 67F that confine the rubber friction part of the gear, and so that the supplementalduring compression of the gear and avoid conflict thereof with the outer coil spring 40. Each spacer plate is .ofiset' locally to form a pair of aligning and locating nubsfor mating engagmeent with the adjacent rubber mats. In

this form of the invention, a separate spring seat 68 provided at the forward end of each stack of rubber sprin'g In the arrangement illustrated for purposes of disclosure, the following parts of the friction mechanism are of the general form shown in, Sproul Patent No. 2,121,833: the central wedge-shaped thrust member or plunger 46; the Wedge shoes 54 and 55; the friction plate arrangement comprising the stationary plates 42, the wear} units.

plates 43 and the movable plates 44; and therelease ele': ment 71. r i

In the illustrated form of' the invention, however, a novel arrangement of intermediate followers is provided; so that the movable friction plates 44 at the open endofi the casing react against and compress the supplemental resistance mechanisms and only the central wedging sys-' tem reacts against the triple-coil spring cushioning mecha nism with the wedging system also loading the friction plate arrangement in transverse directions for dissipat-j ing energy during relative longitudinal movement thereof. The arrangement is such that the front follower 26 abuts H and actuates both the plunger 46 and the movable friction plates 44 during closure of the gear so that the triple-coil; spring, in acting through the central wedging system to resist closure movement of the plunger 46, sets upthe Patented Oct. 18, 1960 the front resistance mechanisms resist closure movement of the friction plates 44 without, however, changing the essential resistance-to-closure characteristic of the wedging system and triple-coil spring part of the gear. In addition to releasing and restoring the wedging system to its release position, the main spring cushioning element, acting through the intermediate follower arrangement, returns the movable friction plates 44 to their release position with or without the assistance of the supplemental resistance mechanism. This provides a measure of safety since, even if the supplemental mechanism should fail, the main elements of the gear continue to operate.

While, for purposes of disclosure, a central main coil spring element is shown flanked on opposite sides thereof by supplemental rubber spring elements, it will be understood that the inventive concept may be embodied in numerous arrangements of main springs and supplemental resistance elements cooperating with various types of friction mechanisms of the above character through intermediate follower arrangements having separably operable parts. In the illustrated arrangement the intermediate follower mechanism consists of a main intermediate follower 74 and supplemental intermediate followers 75 for the supplemental resistance mechanism. The main intermediate follower comprises a hollow, box-shaped, open-ended casting 74B and an integral base plate 74F having a generally circular central portion 74C and integral abutment ears 74E projecting laterally from opposite sides thereof. The base plate is centrally apertured as indicated at 74A in Fig. and provides a seat 748 (see Fig. 2) for the outer coil springs 40 and 40A of the triple-coil spring arrangement, with the hollow, box-shaped casting receiving the release member 71 in longitudinally slidable guiding relation. The supplemental intermediate followers are of generally arcuate shape to conform generally to their arcuate mounting chambers and they are recessed through their front face to form open-sided pockets 751 that receive the abutment ears 74E in longitudinally slidable nesting relation.

As best seen in Figs. 2, 3 and 4, the release member 71 is in the form of a tubular guide stern having an external abutment shoulder 71A forming a spring seat for the inner coil spring 40B.

The shoulder 71A on the tubular release member is arranged for abutment with the base plate 74F to limit forward movement of the release member relative to the main intermediate follower. Preferably the rear end of the release member extends a substantial distance through the inner coil spring 40B to provide desired columnar stability and the forward end of the release member terminates in a contoured abutment face 71F that is engageable with the inner end of the plunger 46 for disengaging the wedging system by returning the plunger during initial release of the gear.

The intermediate follower mechanism cooperates with the conventional parts of the friction system in a novel manner in that the supplemental intermediate followers 75 are driven inwardly by contact with the movable friction plates 44, the outer ends of which project through the open end of the casing for direct engagement with the front follower 26 after limited initial travel thereof. These movable plates are illustrated in phantom lines in Fig. 5 to better disclose their mounting position relative to the intermediate followers 74 and 75. It will be seen that they bridge across the pockets 75P of the supplemental intermediate followers 75. It will be noted from a consideration of Figs. 2 and 3 that the pockets 75P are deeper than the thickness dimension of the ears 74E that are nested therein. This arrangement provides required op erating clearance and permits the main intermediate follower to function independently of the supplemental intermediate follower during compression of the gear.

As is conventional, the main intermediate follower 74 actively cooperates with the wedge shoes 54 and 55 for setting up this friction system and for this purpose it is provided on its front face with outwardly inclined wedge surfaces 74W cooperating with mating wedge surfaces 54W and 55W on the wedge shoes.

Assembly To assemble the gear, the rubber units 65 and spacer plates 66 of the supplemental resistance mechanisms are fed into the supplemental chambers in alternating sequence, with the nubs of the spacer plates assisting in the alignment of these parts. Due to their kidney shape, these elements are tilted during insertion and then rotated to their operative positions. The rubber units are preferably arranged to provide required clearance for the spring seats 68 and for the supplemental intermediate followers 75, which are applied on top of the stack. Then the triple coil spring is inserted, with the release member 71 and main intermediate follower then being applied in order. The main intermediate follower 74 is then forced inwardly into the casing to compress the triple-coil spring and the rubber units until the holes 71H and 74H are brought into registry with aligned holes 351-1 and 36H provided in the casing, with an assembly pin (not shown) being insertable to hold these parts compressed. Finally, the friction mechanism itself is assembled in the front, end of the gear in the conventional manner. The parts are further compressed for removing the assembly pin and releasing the gear.

Operation Upon closure of the gear either in buff or draft loading, relative movement occurs between the front follower 26 and the open end of the casing 29, with the front follower initially engaging and advancing the central plunger 46 to set up the wedging system for transmitting the plunger travel to the main intermediate follower 74 and initially compressing the coil springs. It will be noted that when the gear is in its release position, approximately /1 clearance exists between the base plate 74P of the main intermediate follower 74 and the base of the supplemental follower 75, while only /2 of clearance exists between the front follower 26 and the movable friction plates 44. With this arrangement, the front follower engages the outer ends of the movable friction plates 44 and drives the inner ends of these plates against the front surface of the supplemental followers to transmit loads to the supplemental resistance mechanism through the friction plates rather than through the wedging system itself. This action is apparent from a consideration of Fig. 3, which illustrates the gear in fully closed condition. It will be seen that a slight clearance exists, as indicated at 79, between the intermediate follower and the supplemental followers.

One of the novel characteristics of this gear resides in the fact that the supplemental mechanism does not alter the essential action of the wedging system, the capacity curve for which is shown at in Fig. 7, but rather, the supplemental mechanism, acting through the friction plates 44 to resist closure movement of the front follower 26, develops a separate supplemental capacity curve 81 to give the gear an overall capacity characteristic represented by the curve 82. The supplemental mechanism develops its capacity at regions of the draft gear pocket that are normally empty, but more importantly, the reaction forces transmitted by the supplemental mechanism are developed in direct alignment with the rear lugs and dangerous additional stressing of the casing is avoided. Lateral strains are not aggravated by the supplemental mechanism since it functions independently of the wedging system, and bending or buckling strains at the rear wall of the casing are avoided since the supplemental mechanism acts in line with the rear lugs and merely adds to the compression loading of the rear wall.

During release of the gear, the inner coil spring 40B acts through the release member 71 to displace the plunger n disengage the Wedge system. The other coil springs 40 and 40A return the intermediate follower for restoring the wedge shoes 54 and 55 and, if necessary, the movable plates 44, to their release position. Normally, the supplemental mechanism, through the supplemental followers 75, returns the movable plates to their release position, but should the supplemental mechanism fail, the projecting abutment ears 74E of the intermediate follower will move forwardly of the pocket in which they normally nest and will also engage the inner end of the movable plates to restore the entire friction mechanism to its initial release position. Thus, the present gear has a completely operable arrangement that can and will function independently of the supplemental mechanism, though the overall capacity is correspondingly reduced.

For purposes of disclosure, the draft gear has been illustrated as a type having a nominal closure travel of 2%", though an actual clearance of 2%" is provided between the front end of the plunger and the open end of the casing. The curves shown in Fig. 7 are based on the standard A.A.R. capacity drop test and illustrate the closure performance of the gear.

In this preferred arrangement, the rubber spring units provide a supplemental resistance that is soft during initial closure travel of the gear, and this is desirable for handling light loads, with the rubber units, due to the characteristic parabolic force-closure curve thereof, developing extremely high capacity under severe loading.

It will be apparent that individual corner coil springs may be used in place of the arcuate rubber spring elements.

According to the alternative embodiment of the invention that is illustrated in Fig. 8, the supplemental resistance mechanism is in the form of a set of four hydraulic shock absorbers, generally designated at 86, each of which comprises a base pad '87 forming a closure for one end of a cylinder formed by a circular tube 88, the other end of which is sealed by a wall 89 having a central opening at the axis of the tube, with a piston in the form of a ported disc 90 in reciprocably slidable, sealing relation with the cylinder walls. The piston disc has an outer ring of ports 91 that are open at all times and an inner ring of ports 92 that are normally blocked by a sealing ring 93 under the control of a coil spring 94 that reacts against an internal abutment shoulder 90A provided on the rod 90R for the piston. The piston rod 90R projects through the opening in the front wall 89 of the cylinder and is formed with an external abutment plate 901 that serves as a spring seat for a coil spring 95 that telescopes over the cylinder for automatically restoring the piston to its forward release position following a gear closure.

The intermediate follower 75 in this arrangement is of a generally U-shaped configuration to define a lengthwise pocket that opens completely and accommodates relative movement of the main intermediate follower 74. The parts are otherwise essentially the same as were described in the embodiment of Figs. 1-8 and their mode of operation is similar.

The hydraulic shock absorber units 86, however, have advantageous closure characteristics in that their resistance to closure increases in proportion to the speed of application of the loads on the gear. For example, highvelocity impact loads cause the gear to develop a capacity characteristic as indicated by the curve 96, which is comprised of the characteristic capacity curve 97 attributable to the friction wedge portion of the gear, and the capacity curve 98, which is attributable to the hydraulic mechanism. It will be seen from curve 98 that the hydraulic mechanism exerts its maximum resistance as soon as it comes into play, and this is desirable for enabling the unit to handle the enormous energy involved in the case of high-velocity impact loads. The typical curve for lowvelocity impact loads is shown at 99 and again consists of the portion attributable to the friction part of the gear (curve 97) plus the portion developed by the hydraulic mechanism under low-speed loading (curve 100). Lowspeed, low-energy loads are best handled by soft initial resistance.

The versatile speed-responsive closure characteristics of the supplemental hydraulic mechanism permit the load I response of the gear to be more perfectly conformed to It should be understood that the description of the preferred form of the invention is for the purpose of complying with Section 112, Title 35, of the US. Code and that the claims should be construed as broadly as priorart will permit.

I claim:

1. In a draft gear, a longitudinally extending casing.

having an open end and a closed end, spring means extending longitudinally in said casing and abutting the closed end thereof, resiliently yieldable supplemental resistance means in said casing extending longitudinally alongside said spring means and abutting the closed end of said casing, a friction mechanism in said casing at the open end thereof and including an externally actuatable, longitudinally movable thrust wedge and externally actuatable, longitudinally movable friction-plate means flanking said thrust wedge, said friction mechanism having means loading said friction-plate means transversely in response to longitudinal inward movement of said thrust wedge, and follower means between said friction mechanism and the free ends of said spring means and having an open end and a closed end, spring means ex-f tending longitudinally in said casing and abutting the closed end thereof, a plurality of resiliently yieldable supplemental resistance means in said casing extending longitudinally along opposite sides of said spring means and abutting the closed end of said casing, a friction mechanism in said casing at the open end thereof and including an externally actuatable, longitudinally movable plunger and externally actuatable, longitudinally movable friction plates flanking said plunger, said friction mechanism having intermediate structure loading said friction plates transversely in response to longitudinal inward movement of said plunger, and intermediate follower means comprising a main intermediate follower overlying said spring means and responsive to inward movement of said plunger for compressing said spring means and supplemental intermediate followers overlying said resistance means and responsive to inward movement of said friction plate to compress the re sistance means longitudinally, said main intermediate follower having transverse projections, and said supplee mental intermediate followers having open-sided pockets receiving said projections to accommodate relative longitudinal movement of the parts of said intermediate follower means during closure of said gear, said projections overlying said friction plates for returning said plates during release of said gear.

3. In a draft gear, a hollow casing having an internal peripheral abutment defining a rear chamber and a front chamber, with the front chamber in open communication with the rear chamber and open at its front end, main spring cushioning element disposed centrally in The combination of said rear chamber, a plurality of supplemental, resiliently yieldable resistance elements in said rear chamber flanking said main element, supplemental intermediate followers for said resistance elements and disposed longitudinally between said resistance means and said abutment, a main intermediate follower for said main element and disposed inwardly thereof, said main follower having transverse projections and said supplemental followers having open-sided pockets receiving said projections for independent longitudinal movement therein, and a friction mechanism in said front chamber and including an externally actuatable, longitudinally movable plunger and externally actuatable, longitudinally movable friction plates flanking said plunger, with each of said friction plates overlying one of said upplemental followers and the projection of the main intermediate follower that is nested therein, said friction mechanism including intermediate structure for moving said main intermediate follower inwardly and for loading said friction plates transversely in response to longitudinal, inward movement of said plunger.

4. In a draft gear arrangement, the combination with a hollow casing having an open end, main cushioning means extending longitudinally in said casing and reacting against the other end thereof, supplemental resiliently yieldable resistance means extending longitudinally in said casing alongside said cushioning means, a friction mechanism in said casing at the open end thereof and including an externally actuatable, longitudinally movable plunger and externally actuatable, longitudinally movable friction-member means flanking said plunger, said friction mechanism including means for loading said friction-member means transversely in response to inward movement of said plunger, and main follower means adjacent the open end of said casing and engageable with said plunger and said movable friction-member means for moving the same longitudinally inwardly in said casing; of intermediate follower means inwardly of said friction mechanism and comprising a main intermediate follower overlying said main cushioning means and engageable with said friction mechanism to compress said main cushioning means in response to inward movement of said plunger, and supplemental intermediate follower means overlying said supplemental resistance means and engageable by said movable friction-member means in response to inward movement of said main follower means for compressing said supplemental resistance means, said supplemental intermediate follower means having an open-sided pocket with said main intermediate follower having abutment means projecting intonesting relation within said pocket for longitudinal movement therethrough, said abutment means overlying a portion of said friction-member means.

5. In a draft gear, a hollow, longitudinally extending casing having an open end, main cushioning means extending longitudinally in said casing to react against the other end thereof, a plurality of resiliently yieldable supplemental resistance elements extending longitudinally in said casing in flanking relation to said cushioning means, supplemental intermediate follower means in said casing forwardly of and overlying said resistance means for longitudinal movement therewith, a main intermediate follower member forwardly of and overlying said cushioning means for longitudinal movement therewith, said supplemental follower means and said main intermediate follower member having adjacent portions thereof spaced apart longitudinally to accommodate relative longitudinal movement therebetween, and a friction mechanism in said casing at the open end thereof and including an externally actuatable plunger and externally aetuatable longitudinally movable friction members flanking said plunger, said friction mechanism including means responsive to longitudinal inward movement of said plunger for loading said friction members transversely and for moving said main intermediate follower member'inward- 8 1y, each of said friction members having at the inner end thereof an abutment face presenting adjacent abutment surfaces for separate engagement with said supplemental intermediate follower means and said main intermediate follower member, the overlying portions of said abutment face and said supplemental intermediate follower means being more closely spaced together when said gear is in its release position than the overlying portions of said abutment face and said main intermediate follower memher.

6. The arrangement of claim 5 wherein each friction member is in the form of a plate, said plunger is in the form of a thrust wedge, said main intermediate follower includes a thrust wedge facing said plunger, and transversely spaced wedge shoes are engageable between said thrust wedges for transversely loading said plates.

7. The arrangement of claim 6 wherein said supplemental intermediate followers have open-sided pockets, said main intermediate follower comprises a base plate having abutments projecting transversely into said pockets for longitudinal movement therethrough and a boxshaped casting integral with said base plate and formed with oppositely, outwardly inclined wedge faces on its front end.

8. In a draft gear arrangement for mounting in the draft pocket of a railway car frame, said pocket having front and rear stops, said arrangement including a casing of a length substantially less than the distance between said stops and extending longitudinally in said pocket, a cushioning mechanism in said casing and reacting longi tudinally between said stops through engagement with front and rear follower means, said cushioning mechanism including spring means extending longitudinally in said casing and abutting one of said follower means, a plurality of resiliently yieldable supplemental resistance means extending in lengthwise flanking relation alongside said spring means to abut said one follower means at regions thereof overlying said stops, a pair of supplemental follower means in said casing at opposite sides thereof and disposed forwardly of and in longitudinal abutting relation with the adjacent resistance means, a main intermediate follower member disposed forwardly of and in longitudinal abutting relation with said spring means, each of said supplemental follower means having a pocket therein opening towards said main intermediate follower member, with said main intermediate follower member having integral abutments projecting transversely into nesting relation within said pockets, and a friction mechanism in said casing and including an externally actuatable plunger movable lengthwise through said casing and externally actuatable friction-plate means flank ing said plunger and movable lengthwise through said casing, said friction mechanism including means responsive to inward movement of said plunger for loading said movable friction plates laterally and for moving said main intermediate follower member inwardly, said plunger and said movable friction plates projecting through said casing for engagement wit-h the other of said front and rear follower means for moving said plunger and friction plates inwardly, with the inner end of each one of said friction plates overlying one of said supplemental follower means and the abutment nested therein for compressing said supplemental resistance means independently of said intermediate follower and for restoring said friction plates independently of said supplemental resistanee means.

9. The arrangement of claim 8 wherein said main intermediate follower member and said plunger constitute longitudinally spaced apart, oppositely directed thrust wedges and said friction mechanism includes laterally spaced wedge shoes engageable with said thrust wedges for transversely loading said friction plates.

10. The arrangement of claim 1 wherein said supplemental resistancemeans comprises a pair of longitudinal- 1y aligned stacks of rubber spring units having a generally kidney-shaped cross-sectional configuration.

11. The arrangement of claim 8 wherein each of said supplemental resistance means is in the form of a longitudinally aligned stack of rubber spring units having a generally kidney-shaped cross-sectional configuration.

12. The arrangement of claim 1 wherein said supplemental resistance means is in the form of a set of hydraulic shock absorber mechanisms having a resistanceto-closure characteristic that is variably responsive in proportion to the speed of load application to the gear.

13. The arrangement of claim 8 wherein each of said proportion to the speed of load application to the gear. 7

References Cited in the file of this patent UNITED STATES PATENTS 1,378,393 Woernley May 17, 1921 1,939,303 Herndon Dec. 12, 1933 2,341,699 Dentler et a1. Feb. 15, 1944

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