Abstract:
Railway three-axle, three-motor locomotive trucks are provided with a bolster spring-supported on the truck frame for lateral and vertical movement and having a central opening to accommodate the middle axle motor while minimizing the over-all height of the truck, a plurality of vertically nonyielding body-support bearing elements on the bolster spaced apart transversely and longitudinally of the truck to prevent tipping of the bolster relative to the body, a swivel connection between the body on the bolster, and a draft connection between the bolster and truck frame at a level at least as low as the axles to provide low-level transmission of traction forces between the truck frame and bolster and thereby reduce axle-to-axle load transference and thereby improve adhesion.

Description:
BACKGROUND OF THE INVENTION: 
     1. Field of the Invention 
     The invention relates to railway rolling stock and consists particularly in a three-axle, three-motor electric locomotive truck with improved adhesion characteristics. 
     2. The Prior Art 
     The prior art discloses trucks having bolster suspensions similar to that of the invention, as exemplified by Thomas J. Kolesa, U.S. Pat. No. 2,741,996, and James C. Travilla, U.S. Pat.No. 2,821,149. Neither of these patented trucks, which are each directed to nonmotorized trucks, provides the desirably low level of longitudinal force transmission from the truck frame to the bolster whereby axle-to-axle load transference is minimized in the present invention, nor does either patent disclose a bolster contruction capable of accommodating a large middle axle motor while supporting the locomotive body underframe at a relatively low level. Locomotive trucks have been built with low level longitudinal force transmitting devices between the truck frames and bolsters, but none has provided longitudinally widely spaced bolster mounted body support bearings which cooperate with the low level of truck frame-to-bolster longitudinal force transmission to minimize axle-to-axle load transference. 
     SUMMARY OF THE INVENTION 
     The invention provides a three-axle electric motor truck having motors on each axle with a soft body suspension and means for accommodating a large middle axle motor without elevating the supported locomotive body and for minimizing axle-to-axle load transference. 
     An object of the invention is to provide a three-axle three-motor locomotive truck with a spring-supported bolster in which over-all height of the truck is maintained at substantially the same level as trucks with rigid bolsters. 
     Another object is to provide a three-axle locomotive truck having a spring-supported bolster with means for minimizing axle-to-axle load transference. 
     A further object is to locate the body-support bearings with reference to the bolster support springs such that the bolster members may be relatively shallow to reduce the over-all height of the truck and provide additional vertical clearance for the traction motors. 
     A further object is to depress all truck frame parts underlying bolster parts to the lowest practical level whereby to cooperate with a shallow bolster construction to minimize the over-all height of the truck. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a truck embodying the invention. 
     FIG. 2 is a side elevational view of the truck illustrated in FIG. 1. 
     FIG. 3 is a transverse vertical sectional view taken along line 3--3 of FIG. 1. 
     FIG. 4 is a fragmentary longitudinal vertical sectional view taken along the longitudinal center line 4--4 of FIG. 1. 
     FIG. 5 is a plan view of a truck embodying a modified form of the invention. 
     FIG. 6 is a transverse vertical sectional view along line 6--6 of FIG. 5. 
     FIG. 7 is a longitudinal vertical sectional view taken along the longitudinal center line 7--7 of FIG. 5. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The truck comprises gauged pairs of flanged railway wheels 1 mounted respectively on spaced axles 3, 5 and 7, the ends of which are rotatably received in journal boxes 9. A rigid truck frame comprising a pair of transversely spaced longitudinally extending side members 11 connected at their ends by end transoms 13 and 15 and intermediate their ends by spaced intermediate transoms 17 and 19 has three pairs of spaced pedestal legs 21 depending from each side member 11 and each forming a pedestal jaw vertically slidably receiving a journal box 9. Upright coil springs 23 seated on journal boxes 9 extend upwardly into the hollow interiors of frame side members 11 above the respective pedestal jaws and resiliently support the truck frame on the axles to cushion the truck frame from vertical shocks caused by track irregularities. 
     Traction motors M3, M5 and M7 are respectively journaled on axles 3, 5 and 7 with their noses extending in the same direction from the respective axles and resiliently supported in the usual manner respectively from intermediate transoms 17 and 19 the center portions of which are offset longitudinally of the truck away from the axles 3 and 5 to accommodate the motor noses, and from end transom 15, to provide motor reaction connections to the respective transoms such that all motors apply vertical forces in the same direction to the frame, tending to maintain it parallel to the track and thus avoid varying the load from axle to axle. Gear boxes G3, G5 and G7 drivingly connect the respective motors to the corresponding axles. 
     For vertically yieldably supporting the body underframe U from the truck frame and accommodating swivel and relative lateral movement between the truck frame and underframe U, each truck frame side member is formed with a pair of outboard shelf-like brackets 25 between the middle axle and the end axles, and an elastomeric pad device comprising a plurality of flat horizontal pads 27 of elastomeric material bounded and interleaved by metal plates 29 is seated on each bracket 25 and mounts an upwardly open spring seat 31, in which is seated an upright coil spring 33. 
     A body-support bolster has longitudinally extending side members 35 positioned outwardly of frame side members 11 and each formed with a pair of downwardly open spring caps 37 seated on springs 33. At their ends side members 35 are connected to each other by longitudinally spaced transverse end members 39 and 41, which extend on frame side members 11 between the axle locations, side members 11 being depressed to a low level between middle and end axle pedestals 21, 21. 
     The central portion of end member 39 is offset longitudinally inwardly toward central axle 5 to clear motor M3 and the central portion of end member 41 is correspondingly offset longitudinally toward end axle 7 to clear motor M5, the space above the latter being unobstructed by reason of the opening in the bolster defined by bolster side members 35 and end members 39 and 41. 
     For stably supporting the body underframe U on the bolster, the latter is provided with four transversely and longitudinally spaced upwardly facing, substantially vertically nonyielding, bearing surfaces 43, 43 preferably directly above coil springs 33 at the intersection of bolster end member 39 and side members 35, and 45, 45 preferably directly above coil springs 33 at the intersection of bolster end member 41 and side members 35. The underframe U is provided with four correspondingly postioned downwardly facing vertically substantially nonyielding bearing pads 47, 47 and 49, 49, all elongated on axes tangent to an arc concentric with the swivel axis of the truck for horizontal sliding engagement with upwardly facing bearings 43 and 45 respectively. The location of bearings 43 and 45 directly above springs 33 provides a direct vertical load path through the bolster to the springs, permitting the usage of relatively shallow and light bolster side and end members. 
     For transmitting traction forces from the truck frame to the bolster at the level nearest the rail as possible and thereby minimize the vertical moment arm about which traction forces would act to tip the truck frame, each side member 11 is formed near a middle axle pedestal leg with an outboard bracket 51 at the lowest level consistent with clearance limitations, preferably substantially below the axle centers, and spaced longitudinally of the truck therefrom, the depressed center portion 36 of each bolster side member 35 is formed with a depending bracket 53 at the same level, and at each side of the truck, a longitudinally extending anchor link 55 is pivotally connected to brackets 51 and 53. 
     For transmitting longitudinal forces from the truck to underframe U and defining a swivel axis for the truck, the offset center portion of bolster end member 39 is formed with a center projection toward the middle axle, i.e., in the direction of the center of the quadrilateral defined by bearings 43 and 45 and is formed with an upwardly open vertical cylindrical recess, in which is pivotally received a mating cylindrical boss or spigot 59 depending from underframe U, the bottom of spigot 59 being vertically spaced from the bottom of recess 57 so that these elements function solely as a pivot and horizontal force transmitting member and do not transmit any vertical load from the body underframe U to the truck. 
     All vertical loads are transmitted at the four points defined by bearings 43 and 45 and because of the spacing of these longitudinally and transversely of the truck, the bolster is constantly held against tipping with respect to underframe U, and because of this, the effective point at which traction forces are transmitted from the truck frame to the body underframe is at the level of anchor link 55, thus minimizing the length of moment arm about which the traction forces would act to tip the truck frame and transfer the load from axle to axle. 
     In the embodiment shown in FIGS. 5-7, the truck parts (unless otherwise specified) are substantially the same as in FIGS. 1-4 and corresponding reference numerals are applied to unchanged parts, but consistent with the application of different motors M3a, M5a and M7a the shapes of intermediate transoms 17a and 19a are different as are bolster end members 39a and 41a which are straight transversely of the truck and not offset longitudinally in the manner of end members 39 and 41 of the embodiment of FIGS. 1-4. 
     This construction permits a simplified arrangement of the body support bearings, with bearings 43 eliminated and replaced by loaded center plate comprising an upwardly open vertical cylindrical recess 61 at the center of bolster end member 39a substantially in transverse alignment with springs 33, and underframe U has a depending cylindrical boss or spigot 63 matingly received in recess 61 with its bottom surface 65 in load bearing engagement with the bottom surface 67 of recess 61. 
     Thus in this embodiment, the body load is supported at three instead of four points on the bolster, one of the points, center plate 61, 63 serving both as a load support and swivel connection. Because of the spacing of the center plate and bearing 45 longitudinally of the truck, the bolster cannot tip with respect to the underframe, and this, combined with the low level location of anchor link 55 minimizes axle-to-axle load transference. 
     It will be understood that the invention is applicable to other than three-axle trucks, e.g., to a two-axle truck having a single motor between the axles. 
     The trucks may be modified in various respects as may occur to those skilled in the art without departing from the spirit of the invention and the exclusive use of all such modifications as come within the scope of the appended claims is contemplated.