Railway rolling stock – Special car bodies – Freight
Reexamination Certificate
2000-06-06
2001-12-04
Pape, Joseph D. (Department: 3612)
Railway rolling stock
Special car bodies
Freight
C105S411000, C105S396000, C296S029000, C403S403000, C049S504000
Reexamination Certificate
active
06324996
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to railroad cars, and in particular, to structures defining doorway openings in boxcars.
Railway boxcars are made with two general types of doorway closures. The first is a simple sliding door arrangement in which the boxcar door slides along a track into a position that closes a doorway opening, where it is kept in place by latching the door to the car body structure that surrounds the doorway opening. The second type of boxcar door is a “plug door” arrangement in which the boxcar door is mounted on a track and first rolls longitudinally of the car body into a position aligned with the doorway opening, then moves laterally inward into a sealing position in the doorway when a latching mechanism is operated.
For a plug door, the railway boxcar structure that defines the doorway typically provides a sealing surface around the doorway perimeter, facing laterally outward toward the plug door. The plug door typically has a gasket or other sealing device extending along the perimeter of its interior face to press against the sealing surface.
Doorways for some previously-known boxcars with plug door assemblies have had square corners. This construction creates difficulties, as forces carried through the car body structures concentrate in the car structures defining the corners of such doorway openings and, over time, may lead to stress fractures in the car structure at the doorway corners. The sealing surface of the doorway is typically located on a portion of an inner doorpost, where it is vulnerable to being damaged by equipment used to load or unload the car. Such damage also results in stress concentrations leading to cracks which may progress into a side sill of the car.
In response, boxcar manufacturers designed plug door assemblies with rounded corner gussets in the doorways. Because of the curved surfaces of such rounded corners, there is no point at which stresses can concentrate excessively.
Rounded corners, while improving resistance to damage, diminish the available doorway width at the threshold. If the rounded doorway opening is enlarged to leave as much clear width at the threshold as in a square-cornered doorway, then a larger, heavier door is required, necessitating heavier framing structure surrounding the doorway.
What is desired, then, is a way to achieve required usable doorway width without increasing total doorway width, yet avoid stress concentrations in doorway corners.
BRIEF SUMMARY OF THE INVENTION
The present invention provides an answer to the aforementioned shortcomings of previously known boxcar doorways. Broadly, the present invention provides for corner assemblies that define a doorway opening free from intruding gussets yet carrying structural loads through connections using arcuate surfaces to avoid stress concentrations in the structures defining the corner.
In one preferred embodiment of the invention a railroad car doorway opening for a plug door is defined by a corner connecting member for interconnecting a doorway threshold and a vertical doorway side post, with the corner connecting member including a part of the plug door sealing surface, and a corner insert that fits together with the corner connecting member providing another part of the door sealing surface and defining an angular corner of the doorway opening. The corner connecting member includes a concave connecting surface that extends between the sill and the side post and is spaced outwardly away from the doorway opening, and the corner insert has a convex margin whose shape corresponds to the shape of the connecting surface. The corner insert also has two marginal surfaces that respectively define portions of vertical and horizontal boundaries of the doorway opening and intersect to define an angular corner.
In one embodiment of the invention the corner connecting member has a concave, generally horseshoe-shaped connecting surface. The concave space defined by the connecting surface is filled by a corner insert with a matching convex outer surface and with inner surfaces that form the requisite angular corner to the boxcar doorway.
It is an important feature of one embodiment of the invention that the corner insert which provides a portion of the door seal face and defines a square corner interior angle in the corner of the doorway is attached to the car body structure at a single point, but not to the corner connecting member. With this configuration, significant stresses are not transmitted between the corner connecting member and the insert.
It is another feature of one preferred embodiment of the invention that concave surfaces and mating convex surfaces of the corner connecting member and the corner insert, respectively, are shaped to prevent the corner insert from rotating about the single fastener.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4889055 (1989-12-01), Jamrozy
patent: 5054403 (1991-10-01), Hill et al.
patent: 5088417 (1992-02-01), Richmond et al.
patent: 5802984 (1998-09-01), Thoman et al.
Gunderson, Inc., Boxcar Side Assembly, Jul. 13, 1998.
Baker Andrew A.
Saxton Gregory J.
Blankenship Greg
Chernoff Vilhauer McClung & Stenzel LLP
Gunderson, Inc.
Pape Joseph D.
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