Railway car truck friction shoe spring group

Abstract

A friction shoe for a railway car truck is provided. The railway truck comprises two parallel side frames, a suspension spring assembly supported by the side frames, and a bolster transversely mounted between the side frames and supported by the suspension spring assembly. Each side frame has at least one vertical support face, and the bolster has at least one sloped support face. The friction shoe comprises a sloped wall engaging the sloped support face of the bolster, a vertical wall engaging the side frame vertical support face, and a bottom base engaging and supported by a suspension control spring group which comprises three concentrically nested coil springs which provide a normal force on the column wear plate of between 3000 and 5000 pounds in the static empty railway car truck condition and between 7,500 and 12,000 pounds force under the static loaded railway car truck condition.

What is claimed is: 
     
         1 . A railway car truck comprising:
 two parallel side frames,   a suspension spring assembly supported by the side frames,   a bolster transversely mounted between the side frames and supported by the suspension spring assembly,   each side frame having at least one vertical support face,   the bolster having at least one sloped support face,   and a friction shoe comprising   a bottom base engaging and supported by a support spring group,   the bottom base including a cylindrical spring lug extending downwardly therefrom,   at least one sloped wall engaging the sloped support face of the bolster,   and a vertical wall engaging the vertical support face of the side frame,   and a suspension control spring group having an outer coil spring, a middle coil spring concentric within and inside the outer coil spring,   and an inner spring located concentric with and inside the middle coil spring.   
     
     
         2 . The railway car truck of  claim 1  wherein
 the inner coil spring is shorter than the middle coil spring and the outer coil spring such that the inner coil spring is compressed only when the railway car truck is loaded. 
 
     
     
         3 . The railway truck of  claim 1  wherein
 the proportion of combined spring rates of the suspension control spring group engaging with the friction shoes to the combined spring rates of the suspension springs engaging with the bolster is between 12 and 18 percent in the empty railway car truck condition and between 20 and 27 percent in the loaded railway car truck condition. 
 
     
     
         4 . The railway car truck of  claim 1  wherein the inner coil spring interfaces with the bottom surface of the friction shoe spring lug. 
     
     
         5 . The railway car truck of  claim 1  wherein a composite facing is bonded to the friction shoe vertical support face. 
     
     
         6 . The railway car truck of  claim 1  wherein a polymer wear liner is bonded to the friction shoe sloped support. 
     
     
         7 . The railway car truck of  claim 1  wherein
 a single friction shoe inner, middle and outer coil spring provide a normal force on the column wear plate of between 3000 and 5000 pounds in the static empty railway car truck condition and between 7,500 and 12,000 pounds force under the static loaded railway car truck condition. 
 
     
     
         8 . The railway car truck of  claim 1  wherein
 the friction shoe is comprised of cast iron. 
 
     
     
         9 . The railway car truck of  claim 1  wherein
 the friction shoe is comprised of cast steel. 
 
     
     
         10 . The railway car truck of  claim 1  wherein
 the sloped wall of the friction shoe extends to direct contact with the bottom base. 
 
     
     
         11 . The railway car truck of  claim 1  wherein
 the sloped wall of the friction shoe is comprised of two laterally spaced surfaces with a spacing wall located between the two laterally spaced surfaces. 
 
     
     
         12 . A friction shoe for a railway car truck,
 the railway car truck comprising   two parallel side frames, a suspension spring assembly supported by the side frames, and a bolster transversely mounted between the side frames and supported by the suspension spring assembly,   each side frame having at least one vertical support face,   the bolster having at least one sloped support face,   the friction shoe comprising:   a bottom base engaging and supported by a support spring group,   the bottom base including a generally cylindrical spring lug extending downwardly therefrom,   a sloped wall engaging the sloped support face of the bolster,   and a vertical wall engaging the vertical support face of the side frame, and wherein the friction shoe support spring group is comprised of an outer coil spring, a middle coil spring and an inner coil spring.   
     
     
         13 . The friction shoe of  claim 13  wherein
 the bottom base spring lug includes a hollow opening extending vertically through the spring lug. 
 
     
     
         14 . The friction shoe of  claim 13  wherein
 the friction shoe support spring group is comprised of an outer coil spring, a middle coil spring located concentric with and inside the outer coil spring, and an inner coil spring located concentric with and inside the middle coil spring. 
 
     
     
         15 . The friction shoe of  claim 13  wherein
 the friction shoe support spring group is comprised of an outer coil spring, a middle coil spring located concentric with and inside the outer coil spring, and an inner solid elastomer spring located concentric with and inside the middle coil spring. 
 
     
     
         16 . The friction shoe of  claim 13  wherein
 the friction shoe provides a damping force of between 7500 and 16,250 pounds when the friction shoe is moving at a velocity of between 0 and 19 inches per second. 
 
     
     
         17 . The friction shoe of  claim 13  wherein
 the friction shoe provides a normal force of between 2000 and 12,000 pounds. 
 
     
     
         18 . The friction shoe of  claim 13  wherein
 the friction shoe is comprised of cast iron. 
 
     
     
         19 . The friction liner of  claim 13  wherein
 the friction shoe is comprised of cast steel. 
 
     
     
         20 . The friction shoe of  claim 13  wherein
 the sloped wall extends to direct contact with the bottom base. 
 
     
     
         21 . The friction shoe of  claim 13  wherein
 the sloped wall is comprised of two laterally spaced surfaces with a spacing wall located between the two laterally spaced surfaces.