Axle stabilizer for railway truck
RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. Patent Application Ser. No. 575,346, filed Jan. 31, 1984 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a vibration damping device for use on an axle of a railway truck. 
     2. Description of the Prior Art 
     Vibration dampers used to prevent sporadic oscillations or &#34;hunting&#34; of an axle of railway trucks are old and well known. Such dampers have generally been of the hydraulic type in which a piston having valving reciprocates within a fluid filled cylinder. The cylinder is generally connected to the car body of the railway car and the piston is connected to the axle housing. 
     The axle housing, in which an end of the axle is journaled for rotation, is generally engaged with and supports a resilient suspension member, such as a leaf spring, which resiliently supports the car body of the railway car, as well as any cargo with which the car body is laden. 
     Due to the resiliency of the spring, the axle and the wheels mounted on it tend to, under some conditions, &#34;hunt&#34; at high speeds or make sporadic jerky movements as the truck is forced to accomodtae frequently occuring track curves or rough sections of track. Such movements tend to require a rough, energy inefficient pulling of the car and may, under extreme conditions, cause derailment. Vibration dampers have been used to smooth out or damp such oscillations. These commercially available prior art dampers are of the hydraulic piston and cylinder type having hydraulic flow control valves and relatively complex and expensive seals. 
     Due to the conditions of stress and temperature extremes in which they are forced to operate, the durability of currently commercially available hydraulic type vibration dampers leave much to be desired. Leakage of fluids and stickikng or wear of valves often cause them to be relatively ineffective and require the need for frequent maintenance, repair or replacement. 
     SUMMARY OF THE INVENTION 
     A solid elastomeric pad is interposed between a portion of a railway car body and an axle housing to damper undesirable oscillations of the axle but allow sufficient resilience in curves to provide for steering. The pad, such as a commercially available machine mounting pad, is formed of an elastomeric material sandwiched between and bonded to two metal plates. 
     One of the plates is affixed to a portion of the car body. The second plate is engaged with a linkage which connects it to an axle housing. Upon commencement of erratic movements by the axle the movements are effectively resisted and controlled through the linkage to the rubber pad placed in shear. The rubber pad thus serves to dampen such movements to maintain the axle running in a smooth, energy efficient manner. Due to the essentially solid state of the elastomeric pad the vibration damper so formed is very durable and maintenance free. 
     It is further an object of this invention to provide a design of elastomeric shear pad yaw damper where problems of wear and stress on the linkage are minimized. 
     To accomplish this, the linkage is lengthened considerably, reducing its angular movement relative to its mounts. The linkage is connected to the mounts with spherical bearings, which allow for angular movement without wear. The linkage arm is mounted at an inclined angle when the car is unloaded so that the vertical travel of the railway car due to the variation of weight loads in the car produces minimum strain in the linkage. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view of a railway car having trucks having the vibration damper of this invention; 
     FIG. 2 is an enlarged side elevation view of a truck mounted to a railway car as shown in FIG. 1 and having a vibration damper of this invention; 
     FIG. 3 is a partial top plan view of the truck shown in FIG. 2; and 
     FIG. 4 is an enlarged partial view of FIG. 3 showing the vibration damper in greater detail; 
     FIG. 5 is a partial side elevation view of a truck mounted to a railway car as shown in FIG. 1, and having the alternate-design vibration damper of this invention where the railway car is in a light load condition; 
     FIG. 6 is a partial side view of the truck in FIG. 5 where the railway car is in a heavy load condition; 
     FIG. 7 is a partial top plan view of the truck in FIG. 5; 
     FIG. 8 is an enlarged partial view of FIG. 7 showing the vibration damper in greater detail. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a skeleton type railway car 2 adapted to carry one highway cargo trailer 3. Car 2 has a car body portion comprised of a longitudinally extending center sill 4 having appropriate coupling means, such as conventional railway couplers 5 and 6 at each of its two ends. 
     A plurality of transverse load carrying members, such as bolsters 7 and 8 and bolsters 9 and 10 are rigidly engaged with center sill 4 and extend transverse to sill 4. Bolsters 7 and 8 serve to support a cargo carrying platform, such as platform 11, on each of two sides of sill 4. The tires 12 of trailer 3 are supported by the platforms. A fifth wheel hitch stanchion 13 is engaged with a portion of sill 4 to engage the fifth wheel 14 of trailer 3 to removably engage the trailer with the railway car. 
     Bolsters 7 and 8 are rollingly supported by a truck assembly 15 having an axle 16 to which are mounted a pair of wheels, such as wheel 17, which are flanged to rollingly engage a pair of rails. 
     Axle 16 has at each end an axle housing 18 which supports a resilient suspension means, such as leaf spring 19. 
     Spring 19 is engaged at each of two ends 20 with a set of links which are engaged with a pair of axle stops 21 cantilevered from and rigidly affixed to bolsters 7 and 8. 
     Bolsters 9 and 10 serve to be supported on a truck assembly 22 by having substantially the same structure as at truck 15, described immediately above. 
     Referring now to FIGS. 2 and 3, which are enlarged detail views of truck assembly 15 of FIG. 1, it will be seen that spring 19, of which a portion on each side of axle housing 18 has been cut away for clarity in FIG. 3, is surrounded at an intermediate portion by a spring shackle 82 which maintains the intermediate or center portion of the spring 19 supportingly engaged by a top surface portion 23 of axle housing 18. Adjacent the ends 20 of spring 19 the spring is pivotally engaged by pivotally mounted linkage means, such as links 24 to cantilevered axle stop members 21. With this arrangement the axle and wheel assembly is capable of resiliently supporting the car body of car assembly 2 and, due to the resilience of spring 19 and resilience of pad 26 and the pivotally mounted linkage of links 24 of the spring to the car body, the wheel and axle assembly and axle housings can shift laterally, longitudinally and vertically with respect to the car body to enable the railway car to negotiate track curves and anomalies. 
     However, due to the resilience of the spring, the wheel and axle assembly tends to, under some conditions, undergo sporadic periods of undersirable oscillatory or chattering movement as the wheels seek to follow the tracks. These undesirable &#34;hunting&#34; motions as the wheels seek to follow the track can transmit unwanted vibrations to the car body and its cargo, be detrimental to the track over which the car is travelling and make the car more difficult to pull, which renders it less energy efficient. 
     As best shown in FIGS. 2 and 3, a solid state shock or motion absorber assembly 25 is connected between a cantilevered axle stop member 21, which is rigidly attached to a bolster 8 and comprises a portion of the rigid car body of railway car 2, and an axle housing 18 resiliently connected to the car body by spring 19. 
     Shock or motion absorber assembly 25 is comprised of a resilient solid state slab or pad 26 having a first mounting surface 27 to which is attached, such as by bonding, a mounting plate 28. Mounting plate 28 is rigidly affixed to the member 21 by appropriate mounting means, such as mounting brackets 29 and 30, which are affixed to member 21 by appropriate means, such as welding. 
     Pad 26 has a second surface 31 to which is affixed by appropriate means, such as bonding, a mounting plate 90. A linkage attachment means, such as linkage attachment plate 32, is, as shown, preferably attached to mounting plate 90 of pad 26 by a plurality of mechanical fasteners, such as bolts 33. 
     Plate 32 has an attachment end portion 34 which extends toward axle housing 18. An attachment means, such as clevis 35, having pivot pin holes 36 is provided at end 34. 
     A pivot pin 37 engages a linkage member 38 at a first end portion 39. Linkage arm 38 has an opposite end portion 40 pivotally linked to an attachment bracket 41 which is affixed to an axle housing engagement means, such as extension bracket 42, which is rigidly engaged with the axle housing 18. 
     FIG. 4 is an enlarged detail view of damper assembly 25, as shown in FIG. 3. As shown more clearly in this enlarged view attachment plate 28 and elastomeric pad 26 are secured to attachment brackets 29 and 30 by appropriate means, such as mechanical fasteners 43 and 44. Clevis 35 is formed by having a connector bar 45 rigidly affixed to and extending between position 34 of plate 32 and an extension member 46 for forming substantially U-shaped clevis 35. 
     Cylindrical pivot pin 37 is placed through an opening in each member 34 and 46 and an opening in member 39. The opening in member 39 is just slightly larger than the outside diameter of pin 37 to prevent any substantial longitudinal play or loss of motion between member 39 and 37. With this relationship, movement of linkage 38 is effectively transmitted to plate 32 and linkage 38 is capable of pivotal movement about pin 37 with respect to plate 32. As shown, pin 37 is maintained engaged with clevis 35 by an enlarged head 47 at a first end and removable fastener means, such as cotter key 48, at a second end. A plurality of washers 49 are placed on the pin to prevent end play and rattling. 
     Linkage member 38 is comprised of a connector member 50 welded to an appropriate member, such as round, bar 51, having a threaded portion 52. Threaded portion 52 is threadedly engaged with a coupling nut 53 and is maintained in a desired relationship by means of a jam nut 54. 
     A pair of connector plates 55 and 56 are welded to coupling nut 53 in laterally spaced relation as shown to form a substantially U-shaped connection clevis at end 40 of linkag 38. 
     Attachment bracket 41 has extending longitudinally outwardly from it a connection tongue 57 which is rigidly attached, such as by welding, at end 58 to bracket 41. 
     A pivot pin 59 is placed through suitable openings in the clevis at end 40 and through an opening in connection tongue 57 to pivotally engage tongue 57 to pivot pin 59. The opening in tongue 57 is slightly larger than the diameter of pin 59 to enable linkage 38 to pivot with respect to tongue 57 and to effectively transmit longitudinal motions from the tongue to the clevis at end 40 without any substantial play, and consequently, without any substantial loss of motion between the connection tongue and the clevis. 
     Pivot pin 59 is substantially identical to pin 37 as it has an enlarged head 60 at one end and a cotter key 61 and a plurality of washers 62 at the other end to maintain it engaged in the clevis in a substantially non-rattling manner. 
     An alternate embodiment is shown in FIGS. 5, 6, 7, and 8. 
     As best shown in FIG. 8, the mounting plate 90 is affixed by appropriate means, such as bonding, to the second surface 31 of pad 26. A linkage attachment plate 100, is, as shown, preferably attached to mounting plate 90 of pad 26 by a plurality of mechanical fasteners, such as bolts 33. 
     Plate 100 has an attachment end portion 102 which extends away from axle housing 18 and curves to extend away from pad 26. An attachment means, such as clevis 104, having pivot pin holes 106 is provided on end 102. Clevis 104 is formed by having the inside of curved end 102 rigidly affixed to two plates 105 and 107 for forming substantially U-shaped clevis 104. Additional structural support of end 102 and clevis 104 is provided by gusset 108. 
     Cylindrical pivot pin 110 is placed through an opening in each member 105 and 107 and is journaled through a spherical bearing 112 in linkage end member 114. Linkage end member 114 is attached at one end of linkage 116. The spherical bearing 112 allows for omnidirectional angular movement of linkage 116 without wear on pivot pin 110 or pivot pin holes 106. 
     As shown, pin 110 is maintained engaged with clevis 104 by an enlarged head 111 at a first end and removable fastener means, such as cotter key 113, at a second end. A plurality of washers 115 are placed on the pin 110 to prevent end play and rattling. 
     Linkage member 116 is comprised of a linkage end member 114 welded to an appropriate member, such as round bar 118, having a threaded portion 120. Threaded portion 120 is threadedly engaged with a coupling nut 122 and is maintained in a desired relationship by means of a jam nut 124. 
     A connector plate 126 is welded to coupling nut 122. 
     Attachment bracket 41 has extending longitudinally outwardly from it a pair of clevis plates 128 and 129 which are rigidly attached, such as by welding, to bracket 41 and form a clevis structure. 
     A pivot pin 132 is placed through suitable openings in the clevis plates 128 and 129 and through a spherical bearing 134 in connector plate 126 to engage connector plate 126 to pivot pin 132. 
     The spherical bearing 134 allows for omnidirectional angular movement of linkage 116 with respect to clevis plates 128 and 129 without wear on the clevis plates 128 and 129, the connector member 126, or the pivot pin 132. 
     Pivot pin 132 is substantially identical to pin 110 as it has an enlarged head 130 at one end and a cotter key 131 and a plurality of washers 133 at the other end to maintain it engaged in the clevis plates 128 and 129 in a substantially non-rattling manner. 
     DESCRIPTION OF OPERATION 
     One dampening assembly is preferably placed on each axle housing and therefore each wheel and axle assembly of a single axle truck, as shown, will normally have two dampening structures of this invention. Each of the structures will engage the axle housing in which the axle is journaled for rotation. 
     Each axle housing is allowed a maximum amount of horizontal movement between axle stop surfaces 70, as best shown in FIG. 3. Also each axle housing is allowed to move vertically with respect to surfaces 70 as the movement of the car body causes flexing of the resilient leaf spring 19 and the pivotally mounted linkage comprised of links 24. 
     During installation of damper assembly 25 linkage 38 is adjusted lengthwise by turning threaded portion 52 of round bar 51 into or out of coupling nut 53 so that when connector plate 50 is connected with pin 37 axle housing 18 is substantially centered between surfaces 70 under the normal empty weight of the car. Jam nut 54 is then tightened against coupling nut 53 to maintain the desired length of linkage 38. 
     As car 2 moves, horizontal and vertical forces imposed on an axle housing of the truck are transmitted through the linkage connection from the axle housing into the elastomeric pad with substantially no loss of motion. Due to the resistance to movement of the elastomeric pad in shear the pad effectively serves to absorb and retard motion of the axle housing with respect to the car body and, consequently, provides an effective axle housing stabilizer for an axle housing at each end of the wheel and axle assembly. Although &#34;hunting&#34; is controlled, the pad is sufficiently flexible to allow steering around curves. Also, due to the presence of the pivot pins 37 and 59 linkage 38 enables the axle housing to move vertically up and down with respect to surfaces 70 affixed to the car body and pad 26 imposes a damping effect upon the axle housing as it does move vertically. Also, due to the spacing between the clevises the tongues 39 and 57 are allowed lateral movement along pivot pins 37 and 59, respectively, to enable the axle housing lateral movement with respect to the car body. 
     The operation of the alternate embodiment shown in FIGS. 5 through 8 inclusive is similar to that of the embodiment described above, but differences are present which reduce wear between the moving parts of the arrangement. 
     The linkage 116 is mounted between clevis plates 128 and 129 on bracket 41 and clevis 104 attached to elastomeric pad 26. 
     The connection of the linkage 116 to the clevis 104 at one end the clevis plates 128 and 129 at the other end is accomplished using pivot pins 110 and 132. During the transfer of motion to the elastomeric pad 26, the linkage 116 is deflected in varying directions relative to the pivot pins 110 and 132. 
     To minimize wear on the linkage 116 during the damping movement, the linkage 116 is made as long as is feasible, extending from the bracket 41 to attachment plate end portion 102. The end portion 102 is located substantially away from the edge of the shear pad 26 which is horizontally closest to the axle housing 18. The added length of the linkage 116 minimizes the angular deflections of the linkage 116 relative to the pivot pins 110 and 132. 
     Also, spherical bearings 112 and 134 are used for the journal of the pivot pins 110 and 132 in the ends of the linkage 116. This allows the linkage omnidirectional angular deflection relative to the pivot pins 110 and 132 and virtually eliminates wear at the journal of pivot pins 110 and 132 with linkage 116. 
     As shown in FIG. 7, the linkage 116 in the alternate embodiment is mounted at an inclined angle so that when the railway car 2 is in its lightest-load condition, the linkage 116 is higher at pivot pin 110 than at pivot pin 132. As weight is added to the car 2, the additional load presses downward on the spring 19 and causes the car body, including axle stop members 21, the shear pad 26, and the pivot pin 110 to move downward. In its heaviest-load condition, (See FIG. 8), the linkage is lower at pivot pin 110 than at pivot pin 132. 
     The angle of inclination upward of the linkage 116 and the vertical displacement upward of pin 110 in the lightest-load condition is approximately equal to the angle of deflection downward of the linkage 116 and the vertical displacement downward of pin 110 in the heaviest-load condition. 
     This arrangement minimizes the longitudinal strain on the linkage 116 and the shear strain on the elastomeric shear pad 26 caused by the vertical travel of the railway car body over the range of loads carried by the car 2. 
     The foregoing description and drawings merely explain and illustrate the invention and the invention is not limited thereto, except insofar as the appended claims are so limited, as those skilled in the art who have the disclosure before them will be able to make modifications and variations therein without department from the scope of the invention.