Guide bearing for mounting unit brake beams

In a railroad car truck including spaced side frames riding on a pair of first and second wheeled truck axles, a bolster intermediate said axles and resiliently supported at either end of same from the respective side frames by a spring group interposed between the spring seats of the respective bolster ends and the side frames supporting same, first and second unit brake beams disposed one on either side of the bolster, with the first brake beam having brake heads adjacent each end of same each equipped with a brake shoe for braking application to the wheels of the first truck axle, and with the second brake beam having brake heads adjacent each end of same each equipped with a brake shoe for braking application to the wheels of the second truck axle, said brake beams each having generally flat metallic guide lugs at their respective ends each defining upper and lower, relatively flat, slide mount surfaces, with the side frames on their in board sides defining for the first brake beam a first pair of integral, opposed, substantially coplanar, guide brackets each defining a guide slot lying on the same radius of the first truck axle for defining the first brake beam movement plane, in which said first brake beam guide lugs are respectively mounted for movement longitudinally of said first brake beam guide slots, and with the side frames on the in board sides defining for the second brake beam a pair of integral, opposed, substantially coplanar, guide brackets each defining a guide slot lying on the same radius of the second truck axle for defining the second brake beam movement plane, in which said second brake beam guide lugs are respectively mounted for movement longitudinally of said second brake beam guide slots, and power means for moving the respective brake beams along the respective slots to seat the respective brake shoes against the respective truck wheels to apply the truck brakes,

• the improvement wherein:
• a bearing structure is seated in the guide slot that is formed by each side frame guide bracket and forms a mounting and movement guiding slideway for the brake beam guide lug mounted in the respective guide slots,
• said bearing structures each comprising:
• a plastic material body formed from a resiliently flexible polymer material of dry self lubricating antifriction characteristics,
• said body being of elongate, rectilinear, open top, trough configuration defining a web portion and spaced apart side walls,
• said spaced apart side walls having opposed inner surfacings defined by said polymer material of said body with said inner surfacings defining said slideway,
• said body being seated in its guide slot with said open top facing outward of such slot,
• said side walls having outer surfacings substantially coextensive therewith that include means for frictionally retaining said body in its said guide slot,
• with said inner surfacings of said body side walls being smooth and forming slide surfaces that closely receive within said slideway defined thereby the brake beam guide lug mounted thereby in complementary face to face, cock free, but free slip fit relation thereto,
• said polymer material being characterized by said body side wall inner surfacings defined thereby being corrosion free and resistant to adherence thereto of foreign matter,
• said slideway of said body being oriented relative to its said guide slot in said seated position of said body to dispose same and the brake beam guide lug received therein in coplanar alignment with the brake beam movement plane of its said guide slot,
• whereby, on actuation of said power means, said brake beam guide lugs in being moved in either direction relative to said guide slots respectively are disposed in substantial coplanar relation with the guide slot movement plane of the guide slot in which the respective guide lugs are mounted, and are freely movable therealong, and the respective brake shoes on brake application are presented in flush relation to the respective axle wheels they service,
• said polymer material being further characterized by said inner surfacings of each said body that are defined thereby, effecting through said face to face free slip fit relation, during said movement of said brake beam guide lugs in their respective mounting slideways, resurfacing of the upper and lower surfaces of same, with said body inner surfacings and said guide lug resurfacings hardening in use, whereby same become effectively resistant against wear, in use, for maintaining said coplanar relation of said guide lugs and the flush relation of presentation of the respective brake shoes to the respective wheels they service.