Railway switches and signals – Switch stands – Spiral-cam actuated
Utility Patent
1998-10-05
2001-01-02
Morano, S. Joseph (Department: 3617)
Railway switches and signals
Switch stands
Spiral-cam actuated
C074S097100, C246S412000, C246S413000, C246S414000, C246S393000
Utility Patent
active
06168120
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to operators for railroad implements, such implements including derails and switches. Specifically, the invention relates to actuating mechanisms and safety features for operators for railroad implements.
Railroad implements, such as derails and switches, typically require automatic operators for facilitating movement thereof. Such operators provide the driving force for moving the railroad implement, which is usually rather massive, between an engaged and disengaged position. In the case of a derail, the engaged position is characterized by the derail being disposed above the railroad track so as to engage and derail the wheel of an oncoming railcar. In the disengaged position, the derail is positioned adjacent the track and out of the path of the wheels of the railcar.
Many different types of operators are known. For example, as exemplified in U.S. Pat. No. 5,775,647 to Wyatt, an operator for a railroad switch may include a hydraulic actuator that is driven by hydraulic pressure which may be provided by a hydraulic pump. The pump may be partially energized by solar power. Such prior art operators are characterized by a direct link between the actuator and the railroad implement. As a result, impact forces experienced by the railroad implement, for example, when the implement moves to its engaged position, may be transmitted back to the actuator, thereby resulting in damage to and/or excessive wear on the actuator. Such operators therefore require rather robust and expensive actuators that can withstand such impact forces. It would therefore be desirable to provide an operator in which the actuator is isolated from impact forces, such as those that may be generated by movement or engagement/disengagement of the railroad implement or by impact forces originating within the operator itself.
Hydraulic systems such as the one disclosed in U.S. Pat. No. 5,775,647 typically consume large amounts of energy to operate. These energy requirements may render such hydraulic actuating systems unfeasible as a means to provide dependable low power operation, as might be required if solar energy is desired to be the sole source of power for the operator. As a result, operators that incorporate these hydraulic systems cannot rely on solar power as the sole means for providing energy to the operator. Rather, such operators require supplemental energy sources, such as hydraulic rail pumps actuated by the wheels of a passing train, to ensure dependable operation. Since there is a desire in the industry for operators which provide for maximal use of and sole reliance on inexpensive energy sources, such as solar power, it would also be desirable to provide an operator with a low power actuator that permits energization using only solar power, without the need for supplemental energy sources.
There is also needed an operator with improved safety features for manual operation. It is known to provide for manual operation of automatic operators. Such configurations provide for the use of a manual hand lever, actuated by a human operator to move the railroad implement between the engaged and disengaged positions. Incorporating manual features on automatic operators may present a hazard to human operators because there is potential for accidental energization of the actuator while the human operator is attempting to manually operate the railroad implement. These consequences can have catastrophic results and may result in serious injury. It would therefore be desirable to provide an automatic operator that has manual features with improved safety features that would prevent injury to a human operator during manual operation.
There is also needed an improved operator which provides for easy on-site assembly, maintenance or repair. Many operating mechanisms, including the one disclosed in U.S. Pat. No. 5,775,647, rely on compressed spring members to provide a locking mechanism or to store energy to later be used to provide momentum or power to move the railroad implement. Such springs or biasing elements make assembly and repair of the operator difficult because spring installation typically requires compression of the springs and the application of large forces, sometimes on the order of 150 pounds or more. It would therefore be desirable to provide that a railroad operator provides for the easy and safe installation and removal of spring members which are used in the operator assembly.
SUMMARY OF THE INVENTION
The aforementioned problems and others are solved by the present invention which, in a preferred embodiment, provides an operator incorporating a linkage that isolates the actuator from impact forces. The actuator is adapted to rotate a cam shaft with cams that selectively engage the linkage. In a preferred embodiment, the linkage may take the form of a spring biased toggle which is provided with a pair of tapered rollers to engage respective cams on the cam shaft. Spring elements in a biasing assembly bias the toggle into one of first and second positions and assist rotation of the linkage and movement of the implement without contact from the cam. When the implement moves into its engaged position, the linkage is not in contact with the cam. Thus, impact forces are not transmitted back to the cam, camshafts or actuator. Adjustable stop members may be provided on the toggle to limit its movement. First and second stop positions of the toggle are defined by contact of the adjustable stop members with a stop block that is formed on the operator case.
In accordance with another primary aspect of the invention, the aforementioned isolation permits the operator to be provided with a low power, low-cost actuator, for example, a ball screw driven by an electric motor through a reduction gear assembly. Because the actuator need not be constructed to withstand impact forces transmitted through the linkage, low power actuators suitable for energization using only solar power without the need for hard wiring or supplemental energy sources, may be incorporated into the operator. Alternatively, in accordance with this same aspect of the present invention, a low cost and low power hydraulic actuator may be provided
In accordance with another primary aspect of the invention, the operator is provided with an electric interlock for a hand lever. The hand lever is stored on the battery and controller pack which is provided with a bracket assembly that includes a micro switch engaged by the stored hand lever and in electrical communication with the electric circuit that provides power to the actuator. Removal of the hand lever from the bracket opens the power circuit and prevents accidental energization of the actuator. Thus, the present invention ensures that the actuator will not be energized when a human operator is manually operating the operator using the hand lever.
In accordance with another primary aspect of the invention, a spring assembly tool is provided on the case of the operator so as to assist a technician in installing or removing the compression springs utilized in the operator biasing assembly. In a preferred embodiment, the spring assembly tool includes an angled bracket mounted to the case and an extendable element, such as a threaded fastener extending through the angled bracket and adapted to engage the biasing assembly. When the biasing assembly is moved to an appropriate position, rotation of the extendable member results in compression of the springs to thereby permit an operator to safely assemble or disassemble the biasing assembly.
REFERENCES:
patent: 5052642 (1991-10-01), Peters
patent: 5375796 (1994-12-01), Turner et al.
patent: 5775647 (1998-07-01), Wyatt
patent: 5809833 (1998-09-01), Newport et al.
Banner & Witcoff , Ltd.
Jules Frantz
Morano S. Joseph
Western-Cullen-Hayes Inc.
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