Patent Application
20120051678
The present invention relates to an improved side bearing for mounting on a railway car truck bolster that provides improved control to limit rock and roll characteristics of the railway car in service.
In a typical railway freight train, such as shown in
As is better shown in
Typical side bearing arrangements are designed to control hunting of the railroad car. As a railroad car travels along the railroad track, a yaw excess motion can be induced in the railroad car truck. As the truck yaws, part of the side bearing is made to slide across the underside of a wear plate bolted to the railroad car body bolster. The resulting friction produces an opposing torque that acts to prevent such yaw motion. Another purpose of railroad car truck side bearings is control or limit the rock or roll motion of the car body. Most prior side bearing designs limited vertical travel of the side bearings. The maximum vertical travel of side bearings is specified in the Association of American Railroad Standards. Such vertical travel has limits based on the allowable height of the freight car and the design loading of the freight car.
Accordingly, it is an object of the present invention to provide an improved side bearing which will be selectably responsive to the design loading of a freight car.
A side bearing is provided with improved characteristics to enhance the performance of rail cars with selectable side bearings being available based on the design loading of a freight car.
One embodiment of a side bearing in accordance with the present invention includes a base having a bottom portion and a base wall structure extending generally upwards therefrom. The base wall structure forms a base receiving structure with a generally open centrally located top and a smaller diameter opening in the bottom. A spring is positioned in the base receiving structure. A base insert is placed in the base receiving structure and provides support for the spring.
An elastomer spring of a generally cylindrical shape is positioned within the base receiving structure.
A cap of a generally inverted cup structure has a top portion and a cap wall structure extending generally downward from the top portion. The cap wall structure forms the cap receiving structure having an open bottom.
The top portion of the spring extends into the cap receiving structure open bottom to support the cap.
The base is usually a unitary cast steel or cast iron structure, but could be fabricated. The cap structure is also usually a generally cast steel or cast iron unitary structure, but also in certain embodiments could be fabricated.
The spring is usually formed of a urethane polymer, or other suitable elastomer.
The side bearing base insert is usually a unitary structure made of a structural plastic, but could be a metal structure.
At the standard set-up height of 5.0625 inches (12.8 cm), the cap will be supported by and will preload the elastomer spring for an empty railway car. The base insert can be of varying thickness to affect the support height of the bottom of the spring. Depending on the desired load capacity of the freight car, the height of the base insert and compression characteristics of the spring can vary. The elastomer spring will have a selected load rating to increase the spring stiffness during further travel downward into or over the base of the side bearing. By limiting such downward travel of the cap, the rock of the railway freight car, especially in an unloaded condition, is kept within preselected design parameters. A base insert is provided of varying thickness to support springs of the same height to provide preselected varying load capacities.
In the drawings,
and
Referring now to
Cap 14 is seen to be comprised of a top portion 26 with a wall structure 28 extending generally downward from the outer edge of cap 14. Again, cap 14 is usually a cast steel or cast iron unitary structure, but can be fabricated or machined as well.
Base 12 is seen to also include a base wall top stop surface 38 which is located at the top of base wall 24. Similarly, cap 14 is seen to include a cap inner stop surface 30 which is formed by an inner surface within cap 14 and is adjacent and complementary to base wall top stop surface 38. An elastomer spring 20 is seen to be formed in a generally cylindrical structure, with a bottom 25 supported on base insert 21 top surface 23. Base insert 21 is a unitary structure, usually comprised of a structural plastic, but is could be comprised of steel. Cap inner center projection 32 is received in opening 27 of elastomer spring 20.
Elastomer spring 20 is a typical polymer elastomer available from companies such as the Steinmetz Polymers, and is seen to be comprised of a cylindrical structure. Of course other cross sectional structures of elastomer spring 20 would be operable in this embodiment such as squares or multiple edges such as octagons, but as elastomer spring 20 is located within base wall 24, a cylindrical structure would be preferred.
Referring now to
In
Similarly, base insert 21A would be preselected of a thickness TA that would be as thin as possible to accomplish the necessary support for spring 20 which itself would be selected of a length and compression to accomplish the desired load support for side bearing 10.
In this embodiment, thickness of base insert 21A-TA would be 0.11 inch (0.28 cm) and a complementary designed spring 20 would have a pre-compressed height of 5.30 inch, (13.5 cm) a setup height of 4.45 inch (11.3 cm) and a fully compressed height of 3.82 inch (9.7 cm).
In
Similarly, base insert 21B would be preselected of a thickness TB that would be a bit thicker than thickness TA to accomplish the necessary support for spring 20 which itself would be selected of a length and compression to accomplish the desired load support for side bearing 10.
In this embodiment, thickness of base insert 21B-TB would be 0.178 inch (0.45 cm) and a complementary designed spring 20 would have a pre-compressed height of 5.30 inch, (13.5 cm) set up height of 4.38 inch (11.1 cm) and a fully compressed height of 3.75 inch (9.5 cm).
In
Similarly, base insert 21C would be preselected of a thickness TC that would be as thin as possible to accomplish the necessary support for spring 20 which itself would be selected of a length and compression to accomplish the desired load support for side bearing 10.
In this embodiment, thickness of base insert 21C-TC would be 0.33 inch (0.84 cm) and a complementary designed spring 20 would have a pre-compressed height of 5.30 inch, (13.5 cm) a set up height of 4.23 inch (10.7 cm) and a fully compressed height of 3.60 inch (9.1 cm).
