Patent Publication Number: US-6035788-A

Title: Bogie for rail vehicles

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a bogie for rail vehicles with a frame, two wheel sets and a steering linkage for achieving radial positions of the wheel sets in a rail curve, wherein springs are arranged between the bogie frame and the bearings of the wheel sets, wherein the wheel set bearings are respectively oscillatingly maintained around an axis of rotation above their horizontal central plane in the longitudinal direction of the bogie, and the steering linkage is connected to the wheel set bearings below their horizontal central plane. 
     A bogie with the above mentioned features is known from DE-OS 34 24 531, see FIGS. 4 and 5. In this bogie the wheel set bearings, held in the manner of a suspended pendulum on the frame, are coupled by means of a so-called Watt linkage (see FIG. 2 in particular) for being adjustable in accordance with the radius of the curve. Additional steering rods (FIG. 13), extending diagonally in respect to each other, are provided for stabilization, which are considered to be disadvantageous because of the large structural outlay. 
     It is the object of the invention to achieve a tie-in of the wheel sets with the bogie frame which is free of wear to a large extent and permits radial adjustments of the wheel sets in curved rails. 
     This object is attained in accordance with the invention in that the wheel set bearings are respectively guided in the longitudinal and transverse direction by a laminated steering rod having the axis of rotation located above the horizontal plane, wherein each laminated steering rod is designed to be resilient and acts parallel to the springs. 
     All transverse forces between the wheel sets and the bogie frame are transferred by the resiliently designed laminated steering rods with the axis of rotation integrated into the primary spring system of the bogie, i.e. the laminated steering rods also take over the transverse guidance of the wheel sets. On a straight track the laminated steering rods, together with the steering linkage, furthermore result in a rigid connection of the wheel sets to the frame in the longitudinal direction, which is important for axial parallelism. Regarding the movement over curved tracks, the laminated steering rod connections of the wheel set bearings are used as pivots which permit radial adjustments of the wheel sets by means of a force balance between the wheel and the rail in relation to the curved rail. 
     In order to keep the effects of play in the joints of the steering linkage as little as possible, it is provided in accordance with an embodiment of the invention for the laminated steering rod and the steering linkage to be connected with the respective wheel set bearing asymmetrically in relation to the horizontal center plane in such a way, that the lever arm on the steering rod side is smaller than the lever arm on the linkage side. 
     In view of wear-free pivot movements of the wheel set bearing around the pivot existing on the laminated steering rod, a further embodiment of the invention resides in that the laminated steering rod is connected to the wheel set bearing by a rubber-metal bushing. 
     In accordance with a next embodiment of the invention it is possible to achieve exact measuring conditions in an assembly-friendly manner in that the laminated steering rod is connected with the bogie frame so that it is adjustable in the longitudinal direction, preferably via corresponding toothed strips. 
     The invention will be described in more detail in what follows by means of an exemplary embodiment, which is schematically represented in the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1, a bogie in a perspective view, 
     FIG. 2, a partial area of the bogie in a lateral view. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The bogie has two wheel sets 2 with associated wheel set bearings 4, wherein springs 5 being used as primary springs are arranged between theses bearings 4 and the bogie frame 1. Above the horizontal central plane M a laminated steering rod 6 acts on each wheel set bearing 4 with the interposition of a rubber-metal bushing 7 constituting the axis of rotation 7, and is clamped with its other side on the bogie frame 1. Corresponding toothed strips 1a and 6a formed in the area of this clamping spot make possible the true-to-measurement adjustment of the wheel sets 2 in a simple way. The wheel set bearings 4 are guided in the longitudinal and transverse direction on the bogie frame 1 by the laminated steering rods 6. The laminated steering rods 6 are embodied to be resilient and, together with their rubber-metal bushing 7 as the axis of rotation, act parallel with the springs 5 in all directions; i.e. they are a component of the primary spring system. 
     A steering linkage 3 is connected below the horizontal central plane M of the wheel set bearings 4, which consists of steering rods 3a, reversing levers 3b seated on the bogie frame 1 and a transverse rod 3c connecting the reversing levers 3b. A transverse damper 8 is arranged between the transverse rod 3c of the steering linkage 3 and the bogie frame 1. The entire steering linkage 3 is located in the horizontal plane, so that the installation height in the bogie is very low. In curved tracks, the steering linkage 3 allows the oppositely acting turning of the two wheel sets 2 around their central vertical axis H in the sense of radial adjustments. In the process the wheel set bearings 4 are pivoted around the axis of rotation 7 constituted by the rubber-metal bushing 7 of the laminated steering rods 6. As can be seen in FIG. 2, the laminated steering rods 6 and the steering rods 3a of the steering linkage 3 are asymmetrically connected with the wheel set bearing 4 in relation to the horizontal center plane M, wherein the lever arm a on the steering rod side is smaller than the lever arm b on the linkage side. By means of this the effects of play in the joints of the steering linkage 3 on the radial adjustment of the wheel sets 4 is kept small. 
     The bogie in the arrangement in accordance with FIG. 1 is auto-adjusting, i.e. radial adjustments of the wheel sets 2 result from the force balance between the wheel and the rail in relation to the curved rail. These auto-adjustments are considerably furthered by a profile of the wheel tire, matched to the rail, in the form of a hollow or adaptation profile with a progressively increasing diameter of the running circle in the direction toward the wheel flange. 
     By a slight alteration of the arrangement represented in FIG. 1 it is possible to achieve adjustments of the wheel sets 2 which are a direct function of the turn-out angle between the bogie and the vehicle chassis. To this end the connection of the transverse rod 3c of the steering linkage 3 with a lever at the journal on the vehicle side, for example, is sufficient.