Closure fasteners – Bolts – Sliding
Reexamination Certificate
2001-09-12
2003-03-04
Estremsky, Gary (Department: 3677)
Closure fasteners
Bolts
Sliding
C292SDIG005, C292SDIG003
Reexamination Certificate
active
06527311
ABSTRACT:
DESCRIPTION
This invention relates in general to a door lock for a railroad car, and more particularly to a lubricant free door lock which is mounted on a door of a railroad car to secure the door in an open position or a closed position.
BACKGROUND OF THE INVENTION
The railroad industry employs a variety of railroad cars for transporting products. Many of these cars, such as boxcars or auto rack railroad cars, are enclosed to protect the products or vehicles being transported. Enclosed railroad cars generally include one or more sliding doors to provide access to the interior of the cars. The doors are generally mounted on upper and lower tracks which are attached to the frame of the car. The doors have conventional door locks to maintain the doors in an open position or a closed position. The conventional door locks must be lubricated with a standard lubricant such as grease. The grease attracts particles and other materials, generally creates a dirty environment and causes grease contamination in the interior of the cars.
This problem is especially undesirable in auto rack railroad cars which transport newly manufactured vehicles, including automobiles, vans and trucks. Auto rack railroad cars, known in the railroad industry as auto rack cars, often travel thousands of miles through varying terrain. The typical auto rack car is compartmented, having two or three decks or floors, a frame, two sidewalls, a roof and a pair of doors at each end of the car. The doors protect the auto rack car from illegal or unauthorized entry and prevent theft or vandalism of the vehicles. The doors also prevent flying objects from entering the car and damaging the vehicles. In transit, the doors are secured in the closed position. When the automobiles are being loaded or unloaded, the doors are secured in the open position. Examples of such doors for auto rack cars are generally illustrated in U.S. Pat. Nos. 3,995,563 and 4,917,021.
Each door in an auto rack car includes at least one door lock having a locking pin which engages a socket attached to the frame of the auto rack car. The grease and dirt builds up on these door locks, creates a dirty environment and causes grease contamination inside the auto rack cars which is highly undesirable for the transport of newly manufactured vehicles because the grease and dirt can damage the finishes of the vehicles. The grease also tends to drip or fall off the door locks onto the floor or door tracks of the auto rack car. Workers step in this grease and then track the grease into the new vehicles. Thus, the grease sometimes damages the interior carpeting in the new vehicles.
The Association of American Railroads (“AAR”) requires that the door locks and rollers be lubricated or greased every twelve months or sooner if necessary. The AAR also requires that the date on which the doors and rollers are lubricated be painted on the inside of the auto rack cars for tracking purposes. This requires extensive tracking procedures for this regular maintenance which increases the cost of operating the auto rack cars and decreases the efficiency of the use of the auto rack cars.
Accordingly, there is a need for a new door lock for railroad cars, and in particular auto rack cars, which does not need to be lubricated on a regular basis.
SUMMARY OF THE INVENTION
The present invention solves the above problems by providing a lubricant-free door lock for railroad cars and particularly auto rack railroad cars, which eliminates the need to use grease or other lubricants to lubricate the door locks. The lubricant-free door lock of the present invention generally includes a stainless steel or aluminum cylindrical tube or housing and a cylindrical replaceable plastic bushing, bearing member or collar (primarily referred to herein as a “bushing”) mounted in the housing to prevent the metal-on-metal contact between a stainless steel or aluminum locking pin and the inner walls of the housing. The bushing is preferably molded from a polymer such as an ultra high molecular weight (UHMW) polyethylene although it could be made from other suitable materials such as manganese, bronze, ceramics, moly disulfide filled nylon, delrin or urethane. The bushing eliminates the need for a lubricant between the steel locking pin and the steel inner walls of the housing.
A washer or plate connected to the bottom end of the housing maintains the bushing in the housing. The door lock also includes a spring mounted in the housing between the bushing and an end cap positioned over the locking pin. A limiter or stop extends transversely though the housing, end cap and locking pin to limit the movement of the locking pin.
It is therefore an object of the present invention to provide a lubricant free door lock for doors on railroad cars.
Another object of the present invention is to provide a door lock for doors on railroad cars which eliminates the need to lubricate the door locks.
Other objects, features and advantages of the present invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings, wherein like reference numerals refer to like parts.
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Diagrams of the Radial Door written by Thrall published Jul., 1989.
Burke Michael K.
Peach Walter J.
Pedersen Jake C.
Bell Boyd & Lloyd LLC
Estremsky Gary
ZefTek, Inc.
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