US1797639A - Friction draft gear - Google Patents

Description

March 24, 1931. G F. CQUCH FRICTION DRAFT GEAR Filed Jan. 19, 1926 Patented Mar. 24, 1931 UNITED STATES PATENT OFFICE GLENN IE. COUCH, OF ROCHESTER, NEW YORK, ASSIGNOR T'O THE'GOULD'COUPLER COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MARYLAND FRICTION DRAFT GEAR Application filed January 19, 1926. Serial No. 82,364.

This invention relates to draft gear and, more particularly, to a combined spring and friction n'lechanism in which the frictional resistance is generated by a rotary motion between component members of the gear, said mechanism being particularly suitable as cushioning mechanism in railway car draft rigging.

The principal object of the invention, generally considered, is the provisionof a compact and economically constructed cushioning unit for railway draft rigging in which a rotary element or plunger is threadably mounted in a casing or housing whereby, when the gear is compressed, frictionis generated at the threaded engagement between the parts, said frictional resistance being preferably supplemented by spring resistance.

An object of my invention is the provision of a draft gear inwhich a pair of followers are mounted for axial movement in the opposite ends of a housing, said housing being threaded to an internal plunger adapted to move axially and rotatably with respect thereto, one end of said plunger being preferably frictionally engaged by one follower and the other end receiving a spring resiliently engaging the other follower whereby, when the gear is compressed, the plunger generates frictional resistance with respect to the housing and one follower and spring resistance is provided between the plunger and the other follower.

Another object of my invention is the provision of a cushioning mechanism for railway draft gear involving a follower with a conical recess in one surface thereof, aplunger formed with a corresponding conical end engaged in said recess and threadably mounted in a cooperating housing and spring pressed against the follower whereby, when the gear is compressed, the plunger is rotated with respect to the follower and frictional resistance generated therebetween, said frictional resistance being preferably supplemented by spring resistance.

A further object of my invention is the provision of a draft gear comprising a housing in which is threadably mounted a plunger and on opposite sides of said plunger are mounted followers, said followers being arranged for only axial motion with respect to said housing and one of said followers frictionally engaged by the plunger and the other resiliently engaged by a spring extending from the plunger, said spring being so fastened to the plunger and engaging follower upon its opposite ends that, upon compression of the gear, said spring is stressed torsionally.

Other objects and advantages of the in-' vent-ion relating to the particular arrangement and combinationof the various parts will become apparent as the description proceeds. i

Referring to the'drawings illustrating my invention, the scope whereof is defined by the appended claims:

Figure 1 is a plan View, partially in section, of a railway draft rigging mounted on a car underframe.v and embodying my invention.

Figure 2 is ahorizontal central section of the draft gear or cushioning mechanism em-. bodying my invention.

Figure 3 is an end elevation of the draft gear or cushioning mechanism illustrated in Figure 2. '7

Referring to the drawings in detail, like 'parts being designated by like reference characters, the draft of center sills l of a railway car are illustrated in Figure 1 and on the inner surfaces of the webs of said sills are fastened the usual draft lugs 2, said draft lugs engaging a follower 3 and rear follower l, said rear follower 4 forming a cap or cover over the rear end of the gear or cushioning mechanism casing 5. Around the draft gear or cushioning mechanism a yoke 6 extends, said yoke, in the present instance, being illustrated as of the vertical type and supported at its rear and intermediate portions by carrier irons 7. Said carrier irons 7 are preferably connected to the lower flanges of the draft sills 1 by means of bolts or the like, as illustrated;

The forward portion of the yoke 6 is connected with the stem of the coupler 8, in the present embodiment, by means of a horizontal draft key 9, said draft key extending through corresponding slots in the coupler, yoke and through registering slots 10 in the center sills and similar slots 11 in the associated draft lugs 2.

The follower 3, which engages the front draft lugs 2 at its forward surface, engages at its rear, 01' is formed as a part of, the front follower 12 of the gear or cushioning mechanism proper.

cal surface 13 which is frictionally engaged by a complementary and similarly formed conical surface 14 on a plunger or friction element 15 which is threaded into the body of the housing or casing 5. Said plunger 15 is preferably formed generally hollow so that the opposite end from the friction surface 14 is formed with a recess or cup-shaped portion 16 in which is preferably received a coil spring 17. The coil spring 17 is preferably, but not necessarily, formed of material square or rectangular in section, as illustrated. One end of said coil spring engages the bottom of the recess 16 in the plunger 15and the other end engages the adjacent face of an intermediate follower 18. Positioned between the intermediate follower 18 and the rear follower & is spring means which preferably takes the form of a pair of coil or helical springs 19 and 20, said springs preferably nesting one within the other and being oppositely wound to avoid interference between the coils thereof. For holding all the parts of the gear or cushioning mechanism proper in assembled relation under a predetermined initial tension, a bolt or longitudinal retaining means 21 is preferably inserted through alined axial apertures in the end followers, intermediate follower and plunger, the head of the. bolt, as well as the nut on the opposite end thereof, being preferably countersunk beneath the end surfaces of the front and rear followers to avoid interference between the same and the engagingmei-nbers of the draft rigging, as illustrated particularly in Figure 2, said construction also permitting compression of the gear to the normal extent either by 'countersinking to a corresponding extent or by forming the cooperating follower 3' with a corresponding aperture.

The threaded engagement between the plunger 15 and the housing 5 is preferably ef fected by forming internal threads '22 on the housing, said threads being preferably of relatively great pitch and formed with friction surfaces 23 preferably arranged substantially transverse with their axial sections substantially normal or vertical with respect to the axis ofthe gear, as illustrated in Figure 2. The other portions of" the threads 22 may be defined by sloping substantially conical or helical planes21 joined with the transverse or normal surfaces 23 at the crowns and bases of the threads 22 by cylindrical surfaces '25 and 26, respectively. The threads '22 ap- The inner face of the "front I follower 12 is preferably formed with a com ing, there are formed substantially normal or transverse friction surfaces on the threads of the housing and plunger and sloping oppositely-disposed surfaces which generally engage only when the gear is released, the main friction surfaces normally engaging when the gear is compressed. v

It will be apparent that, on account of the threaded engagement betwen the housing 5 and plunger 15, when the gear is compressed,

the follower 12 moves axially with respect to said housing 5 and the plunger 15 moves axially therewith to the-same extent but is rotated, at the same time, due to its threaded engagement in the housing. The relative rotation between these members depends upon the pitch of the threads, as will be understood, the greater the pitch, the less the relative rotation between theparts. It will be obvious, however, that, in order to effect a closure or compression of the gear, the pitch cannot be smaller than a given ratio which would depend on the angle of friction between the plunger and housing. Between this limiting pitch and a greater pitch, the capacity of the gear may be varied-to agreat degree in accordance with the varying pitch of the threads, 7

In order to utilize the strength of the spring 17 torsionally as well as compression ally, a lug-27 is preferably formed on the bottom of the recess 16 of the plunger 15 and engaged by the corresponding end of the spring 17. A complementary lug 28 is formed on the intermediate follower 18 engaged by the corresponding end of the spring 17. In order to prevent the intermediate follower 18 from turning with respect to the housing 5, the same is preformed noncircular in cross section or provided with an extension or extensions 29 fitting into a corresponding groove or grooves 30 in thehousing 5. This construction permits axial movement of the intermediate follower 29- with respect to the housing 5 but preventsrot'ary or turning movement therebetween. On account of this construction, when the gear is compressed, the plunger 15 is rotated as well as moved axially withrespect to the housing 5 thereby compressing the spring 17 as well as twisting or stressing the same torsiona lly because of the holding lugs 27 and 28 engaging the corresponding ends-of said spring.

In order to prevent the follower 12 from rotating with respect to the housing, insteadof being held for rotary movement of the p'lunger'15 with respeot thereto,'said follower is formed in a manner similar to the follower 18, that is, it is non-circular in cross section or provided with a lug or lugs 31 fittinginto a corresponding recess or recesses 32 in the easing thereby permitting only axial motion between the parts. For uniformity, the rear follower or cap 4 preferably cooperates in a similar manner with respect to the corresponding end of the housing 5, that is, it may be formed of a contour correspondingwith that of the housing 5 so that only axial motion between the parts is permitted, as will be understood.

In assembling the gear, the plunger is preferably first positioned with respect to the housing 5 substantially as shown in Figure 2, the spring 17 placed in position with the end thereof engaging the lug 27 and the follower 29 slipped in place so that the lug 28 thereon engages the other end of the spring 17. The springs 19 and 20 and the end followers may then be applied, the bolt 21 inserted in place and the nut thereon tightened to place the gear under the desired initial compression.

\Vhen the gear is compressed, for example, when associated with draft rigging, as shown in Figure 1, either upon buffing or draft forces being applied to the coupler, a compression will first probably be effected of the springs 19 and 20 until sufficient force is applied to overcome the friction between the conical surfaces 13 and 14 and the friction surfaces on the threads 22 and 22*. hen the gear is further compressed, the end followers move 9;; inwardly, the plunger 15 moves inwardly with the front follower 12 and, at the same time, rotates with respect to the housing 5 generating frictional resistance where it is threaded into said housing as well as at tho conical engaging surfaces 13 and 1 1. This rotary movement between the plunger 15 and the housing 5 causes, in addition to the compression of the spring 17, a torsion or twisting of said spring due to the engagement of the lugs 27 and 28 with the corresponding ends thereof.

In view of the foregoing, it will be apparent that I have devised a desirable draft gear or cushioning mechanism especially adapted for railway, draft rigging in which resistance to compression of the gear is developed, not only by spring means, but also by the frictional engagement between the rotating threaded plunger 15 and the associated housing and front follower. In addispring with the adjacent surfaces for the transmission of tensile rather than merely compressive stress. In addition to the forces mentioned, a slight amount of frictional resistanceis also generated by the movement 1. In a draft gear, a pair of followers, an

internally threaded member receiving both followers, a correspondingly externally threaded member cooperating with the first threaded member and engaged by one of the followers, resilient means between said memher and the other follower, and opposing resilient means to hold said follower in place.

2. In a draftwgear, .a pair of followers, a

housing extending the entire distance be-- tween said followers, a plunger frictionally engaging one follower and threaded into the housing, and a coil spring extending between the plunger and the other follower and engaging lugs on the respective members whereby, when the plunger is rotated with respect to the second follower, the spring is placed under torsional stress.

3. In a draft gear, a pair of followers, a hollow housing provided with opposite recesses into which said followers fit, a hollow I plunger fitting in said housing and threaded thereto, one end of said plunger being closed by a wall frictionally engaging one follower and the open end of the plunger containing a coil spring acting on the other follower and being stressed when the gear is compressed.

l. In a draft gear, a pair of followers, an

internally threaded member engaged by one follower, a member threaded into said internally threaded member and cooperating with the other of said followers, resilient means between said member and the first follower and resilient means between said first follower and another follower for receiving the initial load 011 the gear. 7

5. In a draft gear, a pair of end followers and an intermediate follower, a housing slidably engaged by said end followers and slid ably inclosing the intermediate follower, coil spring means extending between the intermediate and an end follower and frictional spring means extending between the other end follower and the intermediate follower, said means comprising a plunger threaded into said housing and frictionally engaging the end follower, and a coil spring received in said plunger and resiliently engaging the intermediate follower.

6. In a draftgear, an end follower formed with a conical recess, a plunger formed with a complementary conical end fitting in said,

recess and provided with relatively large threads arranged at a relatively great pitch on the exterior surface thereof, a housing surrounding said plunger and in which the follower fits, said housing being formed with internal threads complementary to and engaging the external threads on the plunger for receiving frictionalresistance therebetween, the other end of said housing containing an intermediate follower, a spring positioned between said follower and the plunger, another en-d follower fitting the other end of the housing, and spring means extending between said follower and the intermediate follower.

7Q In a draft gear, a pair of end followers, a housing fitting between said followers, a plunger frictionally engaging one of said end followers and threadably engaging the housing, an intermediate follower contained in said housing and arranged for only longitudinal motion with respect thereto, a coil spring fitting in a recess in the plunger and engaging the intermediate follower, said intermediate follower and plunger being provided with lugs adjacent the ends of the spring whereby, when the gear is compressed and the plunger rotated with respect to the second follower, the spring is placed under torsional stress, and resilient means extending between said intermediate follower and the other end follower.

8. In a draft gear, a pair of end followers, a hollow housing, the ends of which slidably engage said followers, an intermediate follower positioned between said end followers and contained in said housing, a hollow plunger fitting in said housing and threaded thereto, one end of said plunger being formed as a'cone frictionally engaging a complementary surface on the adjacent end follower and the other end of the plunger containing a coil spring acting on the intermediate follower for being stressed when the gear is placed in compression, spring means extending between the intermediate follower and the other end follower, and-a retaining bolt extending through central perforations in the followers and plunger for holding the gear in assembled relation. 7

In testimony whereof I alfix my signature.

GLENN F. COUCH. V

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