The present invention relates, in general, to a self-lubricating system, and more particularly, to a self-lubricating system for a slackless coupling system for a railcar.
Prior to the present invention, a slackless coupling system for a railcar requires periodic lubrication in order to perform efficiently. Typical examples of slackless coupling systems are railcar drawbars and articulated connectors. One type of a slackless-type coupling system uses a ball and race connection assembly. The ball member has a sufficiently smooth surface. Currently used ball member surfaces include electroless nickel-plated, chrome plated, or the like to improve the corrosion resistance of the ball member. The race connection assembly comprises a metal member having a machined surface. This race connection assembly surrounds the ball member so that the ball can rotate within the race assembly and allow the angling movements and maneuverability required to properly negotiate railway track geometry. With the slack removed, greater frictional forces are exerted between the spherical surfaces and the connecting parts. In order to ensure unrestricted movement of the ball member with the race member, care must be taken to ensure that the contacting surfaces are machined to a requisite smoothness. In order to overcome these forces, slackless coupling system manufacturers specify periodic maintenance requirements, such as grease or silicon lubrication at regular intervals to maintain maximum performance, increase product life, and improve efficiency. One known technique for obtaining this lubrication is to provide a substantially solid lubricating liner member, such as manufactured by Kahr Bearing Company, and marketed by them under the trade name “KARLON”, disposed between the outer surface of the ball member, and the inner surface of the race assembly.
Although many lubricating techniques are well known in the art, it is still difficult to maintain a reduced amount of friction between rotating metal-to-metal surfaces. Additionally, machining of both the ball member and the race member to sufficient smoothness and continuously providing adequate lubrication between the ball and race surfaces can be costly and time consuming.
The railway industry is continuously seeking ways to cut costs whether these cuts be in the cost of materials, labor-manufacturing costs, and/or in maintenance costs. Another way to cut costs is to reduce the weight of the freight cars and components for connecting the cars together. This reduction in weight allows for a reduction in the amount of energy or fuel used to pull the train, which ultimately results in higher payloads. Although higher payloads are the ultimate goal of manufacturers, a high level of safety must be maintained.
One way to measure the safety of the railway vehicle is through what is known as an L/V ratio, which is the lateral force over the vertical force of the vehicle. An acceptable L/V ratio limit, as established by the Mechanical Committee of the Standard Coupler Manufacturers (MCSCM) is 0.82, and the recommended L/V ratio limit is less than or equal to 0.74. As manufacturers reduce the weight of these cars, care must be taken to ensure that the L/V ratio is not exceeded. If the L/V ratio exceeds the acceptable limit, the lateral force on the car(s) during turning can exceed the vertical force of the car's weight on the wheels, thus causing the wheels of the car(s) to lift off of the track and the train to derail.
One of the ways in which the L/V ratio can be reduced is by reducing the amount of friction in the joint between the male and female connection members of the coupling system.
The present invention provides self-lubrication to a slackless coupling system for a railway vehicle. A self-lubricating member having a predetermined size and shape is integrally formed from a non-stick material. The self-lubricating member has an inner surface and an outer surface. The non-stick material provides sufficient lubrication between the inner surface of the self-lubricating member, and a first surface of a spherical member coming in contact with the inner surface of the self-lubricating member. The non-stick material of the self-lubricating member allows unrestricted movement of the spherical member, which causes a reduction in the L/V ratio when the self-lubricating member is used in a railcar coupling system.
It is therefore a primary object of the present invention to provide self-lubrication to a slackless coupling system for a railway vehicle.
It is a further object of the present invention to minimize manufacturing costs and time by providing adequate lubrication between the ball and race members of a slackless coupling system.
Still a further object of the present invention is to maintain a reduced amount of friction between rotating metal-to-metal surfaces of a slackless coupling system.
Still a further object of the present invention is to prevent train derailment by reducing the L/V ratio.
In addition to the various objects of the invention that have been described above, various other objects and advantages will become more readily apparent to those persons skilled in the relevant art from the following more detailed description of the invention, particularly, when such description is taken in conjunction with the attached drawing figures and the appended claims.
Prior to proceeding to a more detailed description of the invention, it should be noted that identical components having identical functions have been designated with identical reference numerals for the sake of clarity.
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The invention taught in the present application is closely related to the invention taught in U.S. Pat. No. 6,390,313 B1, “Slackless Drawbar Assembly Using An Improved Ball and Race Connection Assembly”. This patent is assigned to the assignee of the present application. The teachings of this patent are incorporated herein by reference thereto.