Railcar truck roller bearing adapter pad systems
A railcar truck and adapter pad system for placement between a roller bearing and side frame pedestal roof of a three-piece railcar truck. Many different features of the pad and/or the adapter-pad interface are configured to improve stiffness characteristics to satisfy both curving and high speed performance of the railcar truck.
1. A roller bearing adapter pad configured for use with a three-piece truck comprising:
a continuous top plate having a central portion, first and second upturned regions projecting upwardly from opposite edges of the central portion, a first lateral flange projecting outwardly from the first upturned region, and a second lateral flange projecting outwardly from the second upturned region;
a continuous bottom plate having a central portion, first and second upturned regions projecting upwardly from opposite edges of the central portion, a first lateral flange projecting outwardly from the first upturned region, and a second lateral flange projecting outwardly from the second upturned region;
a first outer elastomeric member disposed between the first lateral flanges of the top and bottom plates;
a second outer elastomeric member disposed between the second lateral flanges of the top and bottom plates;
a central elastomeric member disposed between the central portion of the top and bottom plates;
a first substantially hollow portion disposed between the top plate and the bottom plate and between the central elastomeric member and the first outer elastomeric member;
a second substantially hollow portion disposed between the top plate and the bottom plate and between the central elastomeric member and the second outer elastomeric member;
wherein the combined top plate, bottom plate, and elastomeric members provide a longitudinal stiffness of at least 45,000 pounds per inch through a longitudinal displacement of the top plate relative to the bottom plate of up to 0.139 inches from a central position, a lateral stiffness of at least 45,000 pounds per inch through a lateral displacement of the top plate relative to the bottom plate of up to 0.234 inches from the central position, and a rotational stiffness of at least 250,000 pound *inches per radian of rotation through a rotational displacement of the top plate relative to the bottom plate of up to 41 milliradians from the central position when a vertical load of 35,000 pounds is applied to the central portions of the adapter pad.
2. The roller bearing adapter pad of claim 1 , wherein the top plate, bottom plate, and elastomeric member of the adapter pad provide a vertical stiffness of at least 5,000,000 pounds per inch through a vertical displacement of the top plate relative to the bottom plate up to 0.05 inches.
3. The roller bearing adapter pad of claim 1 , wherein the top plate has a uniform thickness, and the bottom plate has a non-uniform thickness.
4. The roller bearing adapter pad of claim 1 , wherein the combined top plate, bottom plate, and elastomeric members of the adapter pad provide a shear strain that does not exceed 120% under maximum displacement.
5. The roller bearing adapter pad of claim 1 , wherein the longitudinal hysteresis is less than about 1500 lbs.
6. The roller bearing adapter pad of claim 1 , wherein the lateral displacement hysteresis is less than about 6,000 lbs.
7. The roller bearing adapter pad of claim 1 , wherein the twist hysteresis is less than about 16,000 lbs*in.