1. Field of the Invention
In general, this invention relates to a rail fastening system, and in particular, to a method and device for securing a rail to a concrete rail tie.
2. Description of the Related Art
Conventional fastening systems for concrete rail ties generally have a cast shoulder, an elastic rail spring clip, and a rail insulator. In this conventional system, the tie is formed with a portion of the cast shoulder imbedded into the tie. To secure the rail to the tie, the elastic rail spring clip is applied to the cast shoulder such that spring arms of the elastic spring clip press the insulator downwardly against a top portion of the rail flange to exert a rail hold down force. At the same time, the body or base of the elastic rail spring clip is secured to the cast shoulder to prevent movement of the rail flange.
This conventional system requires the loose components such as the insulator and the elastic rail spring clip to be wholly installed at the construction site. This process requires a large labor force and considerable time to place the components into a working position. Accordingly, the handling and application of the loose rail fastening components typically comprises a significant part of the overall cost of the installation of concrete railroad ties and rails. Moreover, the loose parts can be easily lost, misplaced or stolen.
In addition to the labor cost of installation, the rail fastening assembly may need to be removed after the rail has been installed to allow the rail to be serviced. Currently, the conventional method requires the elastic rail spring clip element to be xe2x80x9csprayedxe2x80x9d completely out of the cast shoulder to release the other components. After servicing the rail, additional effort must be invested to reset and secure the spring clip, similar to the effort required to mount the spring clip originally.
Thus, there is a need for a rail fastening system which facilitates the installation of the rail fastening components, reduces the cost of installing rails on concrete ties and facilitates and reduces the cost of post-installation rail servicing.
The present invention satisfies the above-described need by providing a method and device for coupling a rail to a railroad tie including a cast shoulder and an elastic spring clip which can be pre-assembled together to reduce the work required at the track site and minimize loss of parts.
Generally described, the present invention provides a fastening system for mounting a rail to a rail tie which includes a spring clip having a pair of arms that can be deflected toward one another from a normal non-deflected position wherein the arms define a normal width of the spring clip. The fastening system also includes a shoulder having an anchoring portion adapted to be anchored to the rail, a receiving portion for receiving the spring clip, and a notch. The receiving portion includes a pair of opposing sides angled to converge as they extend toward the rail and providing a throat location at which the distance between the opposing sides is less than the normal width of the spring clip. The notches provide a width greater than the distance between the opposing sides at the throat location to thereby provide a catch structure which prevents movement of the spring clip out of the receiving portion in a direction away from the rail.
In another aspect of the present invention, the invention provides a method for pre-assembling an elastic rail spring clip to a shoulder. The elastic spring clip includes a substantially horizontal base as well as the two spring arms. The method involves application of the elastic rail spring clip to the receiving portion of the shoulder and movement of the clip into the receiving portion until the spring clip arms reach and pass the throat. The elastic rail spring clip arms compress as they move along the converging sides toward the throat, and the arms thereafter spring outwardly and are caught in the notches.
By providing the converging sides and the notches adjacent to the throat location of the sides, the present invention allows the spring clip and cast shoulder to be pre-assembled prior to the on-site final installation of the rail to the rail tie, thereby reducing the amount of field labor required to install the rail tie. Additionally, the notch prevents a complete decoupling of the spring clip from the cast shoulder thereby reducing the labor required to remove and reattach the spring clip once the rail is installed.