Abstract:
An improved semi-articulated railway power bogie has a pair of multiple axle sub-bogies semi-articulated for creep force turning control while retaining freedom of rocking and relative longitudinal motion. An equalized centered bolster suspension and low load transfer rod linkage maintain high equalization of loads and tractive forces at the wheels to provide overall high adhesion and curving efficiency. Various improvements may include a preloaded resilient compression element in an articulating mechanism for improved sub-bogie turning control, two piece bearing adapters carrying primary spring suspensions and with rubber bushed traction rods and lateral thrust control for transmitting longitudinal and lateral forces to sub-bogie frames, and rubber bushed nose links connecting traction motor nose connections to transoms of the frames.

Description:
TECHNICAL FIELD  
       [0001]     This application claims priority from U.S. Provisional Patent Application No. 60/547,007 filed Feb. 12, 2004. 
     
    
     TECHNICAL FIELD  
       [0002]     This invention relates to railway power trucks, or bogies, and in particular to high efficiency semi-articulated railway power bogies having improved features.  
       BACKGROUND OF THE INVENTION  
       [0003]     U.S. Pat. No. 4,485,743 discloses an eight wheel, four axle semi-articulated railway locomotive power truck. The truck includes dual two axle sub-truck frames connected by a span bolster and semi-articulated for steering control.  
         [0004]     The delivery of tractive effort from the sub-truck frames is through a low mounted traction rod linkage. The truck also features centered support of the bolster between the axles of each sub-truck frame and the retention of freedom for vertical and longitudinal motion between the semi-articulated truck frame ends while maintaining the desired lateral interconnection for steering control.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention provides an improved high efficiency semi-articulated railway power bogie of the general type described in the previously mentioned U.S. Pat. No. 4,485,743.  
         [0006]     The new bogie provides advantages such as improved distribution of locomotive weight to the rails and reduced wheel and rail wear resulting from steering interaction between front and rear power sub-bogies, as well as other features which are inherent in articulated power bogie arrangements. In addition, certain components of the assembly have been modified or replaced by improved designs or mechanisms that improve control, reduce wear, increase operational life or improve serviceability, thus reducing the cost of utilizing bogies of this type in railway operation.  
         [0007]     The semi-articulating lateral tie rod of the previous design is provided with pre-compressed resilient (rubber) bushings in place of spherical bearings. The bushings eliminate clearance and provide controlled stiffness of the lateral end frame connection that increases steering stability and reduces hunting of the connected sub-bogies.  
         [0008]     The pedestals and journal boxes of the previous design are replaced by bearing adapters, which may house sealed axle bearing assemblies carried on the ends of the wheel set axles. The bearing adapters support primary suspension coil spring members with body roll motions controlled by dampers connected between the adapters and the bogie frames. Longitudinal traction and braking forces are carried by traction rods connected between the bearing adapters and the frames, with rubber bushings at connecting joints to provide preloaded frictionless connections. The bushings are preloaded to provide clearance-free guidance, which improves stability at higher speeds.  
         [0009]     Bonded rubber thrust pads on the bearing adapters engage plastic (such as nylon) wear plates on the bogie side frames and control lateral thrust forces from the wheel assemblies. The combination provides improved ride control and life with wear-free traction rod bushings.  
         [0010]     Two-piece bearing adapters are provided which allow wheel/axle assemblies to be easily replaced by removing lower bearing retainers without requiring separation of the adapter upper bearing housings and other connected components. Replacement of the wheel and axle assemblies is simplified by this feature.  
         [0011]     Traction motor support includes a nose link with preloaded rubber bushings. The nose link replaces a nose pack assembly that includes wearing parts with a wear-free assembly.  
         [0012]     These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a fragmentary side view of a railway locomotive having a semi-articulated four axle railway power bogie in accordance with the invention;  
         [0014]      FIG. 2  is a plan view of the railway bogie as seen from the plane indicated by the line  2 - 2  of  FIG. 1 ;  
         [0015]      FIG. 3  is a bottom view of the railway bogie of  FIGS. 1 and 2 ;  
         [0016]      FIG. 4  is a fragmentary cross-sectional view from the plane of the line  4 - 4  of  FIG. 3  showing a resilient bushing joint connection of an articulating transverse link to a sub-bogie frame;  
         [0017]      FIG. 5  is an enlarged fragmentary side view of an end-axle bearing adapter with traction rod connection to a sub-bogie frame;  
         [0018]      FIG. 6  is a cross-sectional view of the bearing adapter application from the plane of the line  6 - 6  of  FIG. 5 ;  
         [0019]      FIG. 7  is a cross-sectional view of a traction rod joint from the plane of the line  7 - 7  of  FIG. 5 ; and  
         [0020]      FIG. 8  is a cross-sectional view of traction motor support link applications from the plane of the line  8 - 8  of  FIG. 3 .  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]     Referring now to the drawings in detail, numeral  10  generally indicates a portion of one end of a railway locomotive having a carbody  11  supported, in an exemplary embodiment, by a four axle semi-articulated railway bogie shown in  FIGS. 1-3  and generally indicated by numeral  12 .  
         [0022]     Railway bogie  12  includes a span bolster  14  that is pivotably connected at its center to the carbody by a center plate  15 . From the center plate the bolster extends longitudinally forward and rearward approximately one-quarter the total length of the bogie to transversely extending support legs  16 ,  18 .  
         [0023]     The bolster is supported in a manner to be subsequently described by first and second interconnected sub-bogies  20 ,  22  having separate frames  23 ,  24  respectively. Each of the frames comprises a pair of generally linear side rails  26  connected together by laterally extending center transoms  27 . The side frames are also connected across the adjacent ends of the associated bogies by end transoms  28 ,  30 , respectively, which are interconnected in a manner to be subsequently described.  
         [0024]     Each of the sub-bogies also includes two pairs of rail engaging wheels  31 , supporting a pair of rotatable axles  32  carrying on their ends preferably sealed cartridge bearings  34  retained in bearing adapters  35  of the sub-bogie frames. Primary suspension means, such as coil springs  37 , are provided between the bearing adapters  35  and slightly raised portions  38  near the ends of the sub-bogie frames for supporting the frames on the wheel and axle assemblies. Secondary suspension means, in the form of resilient pads  39  or other suitable devices, are sandwiched vertically between the ends of the bolster support legs  16 ,  18  and linear portions  41  of the sub-bogie frames, the suspension pads being longitudinally centered between the axles and equidistant from the bolster center plate.  
         [0025]     The primary suspension means permit vertical motion of the individual axle ends relative to the sub-bogie frames within their respective bearing adapters  35  while maintaining substantial equalization of wheel loads. The secondary resilient pad suspensions not only carry vertical loads between the bolster and the sub-bogie frames with resilient cushioning thereof but also permit limited pivoting and lateral motion of the sub-bogie frames with respect to the bolster as will be subsequently more fully described. Placement of the secondary suspension devices equidistant from the bolster center plate and centered between their respective bogie axles provides substantial equalization of vertical loads on the bogie axles.  
         [0026]     Each of the sub-bogies also includes a pair of traction motors  42 , each geared to drive one of the axles  32  and supported between its respective axle and the adjacent center transom  27  of the respective sub-bogie frame. Brake rigging is provided in the form of frame carried brake cylinders  43  acting through brake levers  44  and links  46  to actuate wheel engaging brake shoes  47  in conventional fashion.  
         [0027]     In accordance with the invention, the tractive forces and the dynamic and mechanical braking forces are transmitted from the wheel and axle assemblies to the sub-bogie frames through the axle mounted cartridge bearings  34  and associated bearing adapters  35  by traction rods  48  to be subsequently more fully described. These forces are then transmitted from each of the sub-bogie frames to the locomotive carbody by means of a low level horizontal transfer rod linkage system connected with a pair of stanchions  49  that extend downwardly from opposite sides of the locomotive carbody to locations laterally opposite the longitudinal center of the bogie  12  and the associated center plate  15 . If desired, the stanchions may, alternatively, be formed as extensions of the bolster  14  with the tractive and braking forces being transmitted to the carbody through the center plate  15 .  
         [0028]     Separate linkages from each sub-bogie include longitudinal transfer rods  50  that extend horizontally along the sides of the bogie toward the front and rear from the bottoms of the stanchions  49 , at a level preferably as low as possible and generally about ten inches above the rail. The transfer rods  50  connect with laterally projecting arms  51  of transfer levers  52  that are pivotally connected to the side rails of the respective sub-bogie frames near the longitudinal centers thereof. Levers  52  also include generally longitudinal arms  54 , thereby forming two bell crank mechanisms that are interconnected by a lateral transfer link  55  which extends through the transverse center transom  27  of its respective sub-bogie to interconnect the longitudinal portions of the transfer linkage extending along the bogie sides.  
         [0029]     The transfer linkage not only provides for the transfer of traction and braking loads between the sub-bogie frames and the locomotive carbody through the stanchions but also allows for relative turning and rocking motions of the individual sub-bogie frames with respect to the associated ends of the bolster, which they support. Such turning and rocking motions, generally about the centers of the sub-bogie frames, as well as limited lateral motion with respect to the bolster are permitted by the resilient secondary suspension devices (pads)  39  located between the bolster legs and the sub-bogie frames.  
         [0030]     To properly relate steering or turning motions of the sub-bogies  20 ,  22 , in a manner similar to the disclosure of the referenced U.S. Pat. No. 4,485,743, the adjacent ends of the sub-bogie frames  23 ,  24  are interconnected in semi-articulated fashion to provide interlocking control of the sub-bogie frame turning motions while permitting freedom of the adjacent end portions of the sub-bogie frames for relative vertical and longitudinal motions. In the illustrated embodiment, each end transom  28 ,  30  is fitted with connections at diagonally opposite locations of the bogie frames. These connections are pivotally connected laterally by a transverse link, such as a tie rod  56 . The tie rod positively interconnects the two sub-bogies  20 ,  22  of the bogie  12  for concurrent lateral motions of their adjacent ends, thus requiring equal and opposite turning motions of the two sub-bogies during curving.  
         [0031]     The interconnecting arrangement described provides a construction, referred to herein as semi-articulated, which positively interconnects the two sub-bogie frames to require concurrent lateral motions of their ends. Thus they are interconnected for steering, or relative interrelation of their turning motions to be constrained to equal amounts in opposite directions of rotation or oscillation.  
         [0032]     This provides a balancing of creep forces acting on the two sub-bogies during turning, thus giving a steering function between the sub-bogies that reduces wheel flange loads during turning by causing the axles to take a more normal or radial position with respect to the curving rails during a turn than would be the case if the sub-bogies were not laterally interconnected at their ends. At the same time, freedom is provided in the longitudinal and vertical directions for relative motion between the interconnected end transoms of the sub-bogies. This permits them to freely move with respect to one another in the longitudinal and vertical directions so as to avoid interfering with the weight transfer and load equalization characteristics otherwise provided by the bogie  12 .  
         [0033]     In this regard, the design of the bogie is such as to provide substantially equal distribution of the locomotive weight through the bolster to the separate sub-bogies combined with equal distribution of the weight on each sub-bogie to the axles spaces equidistant from the secondary suspension elements supporting the bolster. This, combined with the low traction linkage system, which efficiently transfers traction forces from the rail to the carbody, provides a very low amount of weight transfer of traction or braking forces from one axle to another.  
         [0034]     Thus, there is provided a very high degree of adhesion efficiency for the bogie. The overall result of the low weight transfer characteristics of the bogie and the steering interconnection of the sub-bogies in a manner that does not adversely affect these good weight transfer characteristics is such as to provide a bogie having substantially greater traction efficiency than conventional four, three or even two axle bogies during curve negotiation as well as during operation on tangent or straight track. Curving efficiency is improved and wheel and rail wear are reduced by the steering interconnection of the sub-bogies.  
         [0035]     In accordance with the present invention, the features of the transverse link described above are improved by the application of pre-compressed resilient bushings in the pivotal connections between the transverse link, or tie rod  56 , and the adjacent end frames  23 ,  24  of the sub-bogies. In particular, referring to  FIGS. 1-4 , the tie rod  56  has an eye  58  at both ends, each eye having a cylindrical opening  59  receiving a connecting pin  60  with an annular or tubular rubber bushing  62  compressed between the pin and the opening. The pin  60  includes end flanges  63 , which are bolted to bifurcated fingers  64  of a connector  66 , provided, one on each bogie frame, on laterally opposite sides of the bogie  12 .  
         [0036]     The pre-compressed resilient (rubber) bushings  62  provide non-wearing connections without clearance and allowing limited pivoting, but having a controlled stiffness that positively turns the sub-bogies together to provide improved stability in curve negotiation at higher speeds.  
         [0037]     Referring to  FIGS. 1, 3 ,  5  and  6 , the pedestals and journal boxes of the prior patented truck are replaced in accordance with the invention by the cartridge, or other, bearings  34  received in downwardly open recesses  68  in upper housings  69  of the bearing adapters  35 . The adapters include two pieces, including upper housings  69 , which receive and transfer vertical, lateral and longitudinal loads from the bearings  34 . Separate bearing caps or retainers  70  are secured across open ends of the recesses  68  to maintain the bearings in position. The retainers  70  are removable to facilitate easy removal of wheel and axle assemblies from the bogie for service or replacement. The upper housings  69  and connected components remain in place without requiring disturbance of their fasteners during wheel assembly and bearing service.  
         [0038]     The connected components referred to include the primary suspension coil springs  37  which are received in pockets  72  in the slightly raised portions  38  of the frames  23 ,  24  (see  FIGS. 5 and 6 ). One of telescoping dampers  73 , connected vertically between the frames and a bearing adapter  35  for each axle, is also shown.  FIG. 6  also illustrates in cross section, one of rubber-bonded thrust pads  74 , mounted on upstanding abutments  76  of the adapter upper housings  69  and engagable with suitable wear plates  77 , such as nylon or other plastic, mounted inside the frame pockets  72 .  
         [0039]      FIGS. 1, 3  and  5  best illustrate the traction rods  48  connected longitudinally between the adapter upper housings  69  and depending connecting walls  78  of the sub-bogie frames  23 ,  24 . A cross-sectional view of the attachment to frame  23  is shown in  FIG. 7 .  
         [0040]     Each traction rod  48  has an eye  78  with a cylindrical opening  80  at each end. Within the opening  80  a resilient rubber bushing  81  is compressed between the eye and a steel insert  82 . The insert has a slight barrel shape to retain the bushing  81  in place in the eye  78 . The insert  82  is secured to the frame  23  by a bolt  84  extending through cooperating openings of the insert and the frame walls  78 . A similar connection is provided between the other eye  78  of each traction rod  48  and its associated bearing retainer upper housing  69 .  
         [0041]     In use, lateral motion of the axles  32  in the frames  23 ,  24  is constrained by the retainer mounted thrust pads  73  engaging the frame mounted wear plates  76  to resist lateral thrust forces imposed on the wheels and axles during locomotive operation. Longitudinal traction and braking forces are transmitted between the axles  32  and the frames  23 ,  24  by the traction rods  48 . The rubber compression bushings  81  provide preloaded resilient connections without clearance, which assures the same characteristics, with and without traction forces, which do not change over time due to absence of wear in the connections. The preloaded connections of the traction rods provide more stable operation of the bogie at high speeds due to the absence of clearance in the connections.  
         [0042]     As a further feature, the bogie  12  also provides an improved traction motor nose suspension, which utilizes the benefits of rubber compression bushings to provide longer service life and improved serviceability to the traction motor mounting.  FIG. 8  best illustrates the arrangement which provides a nose link  85  for supporting the nose, or inner side, of each traction motor  42  from the center transom  27  of the associated sub-bogie frame  23 ,  24 . Each nose link has upper and lower support pins  87  received with pre-compressed rubber bushings  88  in eye openings  89  adjacent each end of the link. The pins have flattened ends  90  which are bolted to the transom  27  or to support arms  92  extending from the traction motor noses. The opposite end of each traction motor is conventionally supported by bearings carried on the associated axle.  
         [0043]     The nose link suspension replaces a nose pack arrangement which includes wearing components that are eliminated in the new suspension, thereby extending the service life of the nose suspension. Removal of a traction motor is also simplified, since detachment of the nose end requires only unbolting of the pins from the support arms while the motor nose is supported.  
         [0044]     While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.