Abstract:
A railway bogie includes at least two spring units per one wheel, a bogie frame and an essentially single piece adapter which bridges the spring units and is arranged between the spring units on the one side and the bogie frame on the other side.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a railway bogie comprising at least two spring units per one wheel and a bogie frame. 
       BACKGROUND DISCUSSION 
       [0002]    From UIC standard a bogie with helical springs is well known in which the axlebox suspension consists of helical springs in combination with friction damping. The springs rest on support arms integral with the lower part of the axlebox housing and are connected with the bogie frame using caps integral with the bogie frame for taking up the top of the springs. 
         [0003]    US 2002-0089 102 A1 discloses a hydraulic spring comprising a membrane. This document discloses that the hydraulic spring is for use in rail vehicles especially as a primary spring. 
         [0004]    Further, the catalogue of the company ContiTech Luftfedersysteme GmbH in Hannover, Germany, “Air Spring Systems for Modem Rail Vehicles”, printed and distributed in October 1998, discloses the use of hydraulic springs comprising a membrane in two-axle bogies. 
         [0005]    One object of the present invention is to provide an improved railway bogie comprising at least two spring units per one wheel and a bogie frame, so that various types of spring units in connection with also various types of axleboxes having all diverse dimensions can be connected to the bogie frame having standardized dimensions in an easy and reliable manner. 
       SUMMARY 
       [0006]    A railway bogie comprises at least two spring units per one wheel, a bogie frame, and an essentially single piece adapter which bridges the spring units and is arranged between the spring units on the one side and the bogie frame on the other side. 
         [0007]    The adapter is used in an advantageous manner to adapt various types of spring units in connection with various types of axleboxes having all diverse dimensions to the bogie frame having standardized dimensions without the need of modifying the bogie frame. Just the adapter is modified according to the used type of spring units and axlebox, whereby any modifying of the adapter can be done more easily and in a more cost-efficient way than it could be done with the bogie frame itself. 
         [0008]    With the accurately pre-fabricatable adapter it can further be assured that the two spring units are mounted to the bogie frame exactly with a prescribed distance between the principal axes of the two spring units, whereby every deviation from the prescribed distance would result in a tangential deviation of the spring units and therewith in an undesirable modification of the spring characteristic. 
     
    
     
       BRIEF DISCUSSION OF THE DRAWING FIGURES 
         [0009]    Further advantages, features and details of the invention are described with respect to one preferred embodiment of the invention with reference to the accompanying drawings briefly described below. 
           [0010]      FIG. 1  is a longitudinal cross section in the region of one wheel of a bogie. 
           [0011]      FIG. 2  is a sectional view along the line B-B of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION  
       [0012]      FIG. 1  shows a longitudinal cross-section in the region of one wheel  2  of a bogie of the so-called Y 25 type, whereby the cut is directed according to a plane being defined by the axes of rotational symmetry of a first and second hydraulic spring. The pictured section of the bogie comprises an axlebox  10  with a rolling bearing  4  mounted in a middle region of the axlebox  10 . The rolling bearing  4  supports one end of one of the two axles of the bogie. 
         [0013]    A base of the axlebox  10  is extended to the left and the right side forming a cup shaped region  12  at each of the sides. Each of the hydraulic springs comprises a spring element  20  which is attached to each of the cup shaped regions  12  of the axlebox  10 . A metallic centerpiece  26  is located in the center of each of the spring elements  20 . 
         [0014]    These two centerpieces  26  are attached to one bridging adapter  50 . Therefore the centerpieces  26  and the bridging adapter  50  have bores for connecting the centerpieces  26  with the bridging adapter  50  via two bolts  52  pictured uncut in  FIGS. 1 and 2 . In other embodiments, the bolts  52  can be integral parts of the centerpieces  26  or of the bridging adapter  50  or the centerpieces  26  can be connected to the bridging adapter  50  by any other connecting means. 
         [0015]    The bridging adapter  50  is attached to a longeron of a frame  6  of the bogie. This longeron extends in a longitudinal direction parallel to the rails and is pictured uncut in  FIG. 1 . Preferably the bridging adapter  50  is connected to the bogie frame  6  by welding. 
         [0016]    In the following description, just the left cup shaped region  12  in connection with the left spring element  20  is described in detail, because the same applies to the right cup shaped region  12  in connection with the right spring element  20 .  FIG. 2  shows a sectional view along the line B-B of  FIG. 1 . The spring element  20  comprises sleeve shaped elastomeric elements  22  and intermediate sleeve shaped metallic elements  24  in an alternating succession, whereby the elastomeric and the metallic elements  22  and  24  are connected by way of vulcanization. Also the centerpiece  26  is connected by way of vulcanization to its adjacent elastomeric element  22 . 
         [0017]    The spring element  20  is secured to the respective cup shaped region  12  of the axlebox  10  via a sealing ring  42 , which is attached to the axlebox  10  via screws  44 . In other embodiments the spring element  20  also can be directly vulcanized to the cup shaped region  12 . The spring elements  20  forms together with the respective cup shaped region  12  of the axlebox  10  a volume for a fluid  30 , particularly a hydraulic fluid. This volume is at least partly filled with the fluid  30 . The centerpiece  26  is prolonged into the volume forming a plunger shaped region  28 . Thereby at least a disk shaped region at the end of the plunger shaped region  28  is dipped into the fluid  30 , so that this arrangement fulfils the function of a damper. The cup shaped region  12  of the axlebox  10  together with the respective spring element  20  and the fluid  30  form together the hydraulic spring. 
         [0018]    In another embodiment of the invention, a hydraulic spring can be used, e.g. according to the already cited US 2002-0089102 A1, comprising a membrane instead of the plunger shaped section  28  of the centerpiece  26 , whereby the cup shaped region  12  of the axlebox  10  is then also one part of the housing of the hydraulic spring.