Railroad car truck damper wedge fittings
A damper wedge for a railroad car truck includes a friction member that rides on the wear plate of the side frame column of the railroad car truck and a non-metallic wear surface; and a spring seat that, in use, engages a spring of the railroad car truck. The inclined damper wedge surface has a primary angle alpha, and a secondary angle beta. The spring seat has an axial centerline. The inclined damper wedge surface has a curvature. The curvature has a working point. The damper wedge has a datum plane that is normal to the non-metallic wear surface and that contains the axial centerline. The axial centerline meets the inclined damper wedge surface at an intersection point that is the center of a contact patch. The working point is located in a central region of the contact patch, or working surface patch, downslope of the intersection point.
1 . A damper wedge for a railroad car truck, said damper wedge being formed to co-operate with a corresponding bolster pocket, wherein said damper wedge comprises:
a friction member that, in use, is configured so as to movably engage a wear surface of a side frame column of the railroad car truck, said friction member having a non-metallic wear surface; a spring seat that, in use, engages a spring of the railroad car truck, said spring seat having an axial centerline; and an inclined damper wedge surface, said inclined damper wedge surface having a primary damper wedge angle, and a secondary damper wedge angle;
said inclined damper wedge surface having a compound curvature;
said inclined damper wedge surface being a machined surface;
in operation, said curvature of said inclined damper wedge surface engaging the bolster pocket in rolling point contact;
said curvature of said inclined damper wedge surface having a working point that engages the bolster pocket when the railroad car truck is at rest;
said damper wedge having a datum plane that is normal to said non-metallic wear surface and that contains said axial centerline of said spring seat, said axial centerline meeting said inclined damper wedge surface at an intersection point; and
said working point is located on said inclined damper wedge surface downslope relative to said intersection point; and said working point is located at a center of a contact patch, said contact patch having a radius of less than 1.5 inches.
2 . The damper wedge of claim 1 wherein said inclined damper wedge surface is a spherical surface.
3 . The damper wedge of claim 1 wherein said working point is offset between ¼″ and ¾″ further away from said non-metallic wear surface of said friction member than is said axial centerline.
4 . The damper wedge of claim 1 wherein said non-metallic wear surface is offset from said axial centerline by a first distance, x 1 ; said working point is offset from said axial centerline by a second distance x 2 ; and a ratio of x 1 :x 2 is in the range of one of (a) 21:2 to 21:8; and (b) 10:3 to 40:3.
5 . The damper wedge of claim 1 wherein said non-metallic wear surface has an overall height y 1 and said working point lies in the range of ⅜ to ⅝ of y 1 up the height of said non-metallic wear surface.
6 . The damper wedge of claim 1 wherein said curvature has a radius of curvature of less than 35 inches.
7 . The damper wedge of claim 6 wherein said radius is in range of 15-30 inches.
8 . The damper wedge of claim 6 wherein said radius is 20 inches, +/−½ inch.
9 . The damper wedge of claim 1 wherein said angle alpha is between 30 deg and 50 deg., and said angle beta is between 5 degrees and 20 deg.
10 . The damper wedge of claim 1 wherein said contact patch that has a radius of less than 1 inch.
11 . The damper wedge of claim 1 wherein said damper wedge has first and second end walls; said inclined damper wedge surface is located between said first and second end walls; and said datum plane is mid-way between said first and second end walls.
12 . The damper wedge of claim 1 wherein said damper wedge includes an internal web extending between said inclined damper wedge surface and said friction member, and said working point is aligned with said internal web.
13 . The damper wedge of claim 1 wherein said working point is along said datum plane.
14 . The damper wedge of claim 1 wherein said damper wedge is at least partially hollow.
15 . The damper wedge of claim 1 in combination with the bolster pocket.
16 . A railroad car truck comprising the damper wedge of claim 1 and at least one self-steering apparatus.
17 . The railroad car truck of claim 16 wherein said self-steering apparatus includes a rocker located between a side frame pedestal and a wheelset axle bearing.
18 . The railroad car truck of claim 17 wherein said railroad car truck has a side frame mounted to rock laterally sideways, said side frame having a lateral rocking stiffness k pendulum ; said railroad car truck has a bolster mounted on spring groups; and said spring groups have a lateral stiffness k springshear , and k pendulum is less than k springshear .
19 . The damper wedge of claim 1 wherein said damper wedge has first and second end faces, said datum plane is defined mid-way between said end faces, and said damper wedge is asymmetric.