The present invention generally relates to machines for use in the maintenance of a railroad track, and more particularly to a toggle slide-plate for use in a railroad spike-pulling machine.
Maintenance of railroad tracks and the periodic replacement of wooden railroad ties or worn rails or rail segments require the removal of spikes from the ties and corresponding tie plates to separate the rails from the ties and position the new ties. In the present application, “spikes” will be understood to mean rail fasteners including standard “cut” spikes, hairpin spikes, screw spikes, and other equivalent rail fasteners. Railroad spike-pulling machines, of the type disclosed in commonly assigned U.S. Pat. No. 4,538,793, incorporated by reference, accomplish the removal of these spikes with a gripping or clamping assembly generally including a pair of reciprocating jaws, where each jaw is located on a corresponding side of the rail. Each jaw also has a claw member at a distal jaw end that is operable for gripping the head of the spike. Once the claw member has gripped the spike, a mechanical linkage lifts the jaws upward so that the spike is pulled from the tie and the tie plate. The mechanical linkage for lifting the clamping assembly generally includes fluid power cylinders, as known in the art.
One problem that arises during operation of these assemblies is that as the machine travels along the track, the jaws are subjected to a perpendicular force. This force can cause the jaws to twist, misaligning them and preventing the claw members from properly gripping the tie spikes.
To address this potential problem, supporting connecting links were developed to maintain the alignment between the jaws and prevent them from twisting. A lower end of each pair of connecting links is attached by brackets to the pivotable intermediate section of the jaws. A hydraulic cylinder is configured to maintain a connection between the lower ends of the connecting links, and helps to prevent the jaws from twisting. An upper end of each of the connecting links is connected to a pair of spaced apart guide slots which define the travel limits of the links during movement of the jaws.
The opposite ends of the guide slots are generally supported by a plate assembly. Current plate assemblies generally include a pair of endplates supported for vertical movement by a mid-plate. The opposite ends of the mid-plate are slidably housed in channels in a supporting frame member. The mid-plate slides up and down the channels as the jaws move away and towards the spike, respectively. One problem that arises with these plate assemblies is that the ends of the mid-plate become worn down through sliding on the channels, requiring the plate to be replaced. To replace the plate assembly, the connecting links must be unscrewed from the endplates, and then the endplates must be removed from the mid-plate, so the mid-plate can be removed from the machine.
However, this process can be very time consuming because the plate assembly is virtually inaccessible after assembly of the machine, thus reducing operating efficiency. Furthermore, replacement of the mid-plate requires the use of special tools that can access the plate assembly. Also, the entire mid-plate needs to be replaced in current plate assemblies, even though only the ends of the mid-plate have been worn down. Therefore, replacement of the entire mid-plate is not cost-effective. In addition, during operation of the tool, the plurality of welds that secure the endplates to the mid-plate can become loosened, reducing the effectiveness of the plate assembly by permitting twisting of the jaws.
Therefore, there exists a need for a plate assembly that can be easily replaced after the ends of the mid-plate become worn down. There also exists a need for a plate assembly where the ends of the mid-plate can be replaced without the use of special tools and without the need to disassemble the spike-pulling machine. Also, there exists a need for a method of replacing the worn down ends of the mid-plate without the need to replace the entire mid-plate. Finally, there exists a need for a plate assembly that is accessible after assembly of the machine, so that adjustments can be easily made.
The above-listed needs are met or exceeded by the present toggle slide-plate, which allows the user to easily replace the ends of the mid-plate after they have become worn down from repeated operation of the machine. Also, the present slide-plate provides a method for replacing only the worn down portion of the assembly, increasing cost-effectiveness and eliminating the need to replace the entire mid-plate. In addition, replacement of the ends of the mid-plate does not require the use of special tools. The present plate is also easily accessible after assembly of the spike-pulling machine, so that adjustments can easily be made when necessary.
More specifically, the present slide-plate provides a mid-plate having a first end and a second end, a first endplate connected to the first end, a second endplate connected to the second end, and a wear pad secured to each of the first endplate and the second endplate.
In another embodiment, a toggle slide-plate is provided for use in a spike-pulling machine and configured for facilitating the movement of a pair of pivotable arms each having a spike-pulling claw configured for removing a spike from a railroad tie, the pair of pivotable arms being configured for moving in a direction perpendicular to a longitudinal axis of a rail and the toggle slide-plate being configured for preventing twisting of the pair of pivotable arms. The toggle slide-plate includes a mid-plate having a first end and a second end, a first endplate connected to the first end and a second endplate connected to the second end. A groove portion is located in a middle of both the first endplate and the second endplate, each groove portion further including at least one hole. A wear pad is configured to be removably secured to each groove portion, each wear pad further including at least one throughbore corresponding with the at least one groove portion hole, and a pair of fasteners are configured for insertion into each pair of groove portion holes and wear pad throughbores. Each pair of fasteners is configured for securing the first endplate or the second endplate to each wear pad.
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A mechanism is provided for supporting the pivotable arms 14 during movement in directions perpendicular to the longitudinal axis of the rail 25, and for preventing twisting of the arms. This mechanism generally includes a pair of connecting links 26, the upper ends 27 of which are pivotally connected to the slide-plate 10. Lower ends 29 of the connecting links 26 are each pivotally connected by a corresponding bracket 30 to a midpoint 32 of the corresponding pivotable arm 14. It is contemplated that the connecting links 26 are provided for supporting the pivotable arms 14 against forces on the pivotable arms in the direction of the longitudinal axis of the rail 25. While shown as adjustable, the links 26 may alternately be fixed, depending on the application.
The present toggle slide-plate 10 is configured for preventing twisting of the pair of pivotable arms 14 during operation of the machine 12. For controlling operational movement of the arms 14 in a direction perpendicular to the longitudinal axis of the rail 25, a fluid power cylinder such as a hydraulic cylinder 34 is provided to connect the arms 14 at their respective midpoints 32.
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In the preferred embodiment, the mid-plate 36 and the first and second endplates 42 and 44 are secured together, as by welding, to form a unitary piece, preferably manufactured out of ASTM A36 steel, or other materials having equivalent durability, strength and cost characteristics, as are known in the art. Unlike current plate assemblies which can become loosened during operation of the machine 12, it is contemplated that by providing the present toggle slide plate 10 as a unit, it will not be as greatly affected by the torque generated during operation. The first and second endplates 42 and 44 preferably have a thickness of approximately 0.75 inch, while the mid-plate 36 preferably has a thickness of approximately 1 inch. While other thicknesses are envisioned, it is contemplated that the preferred first endplate 42 and second endplate 44 thicknesses will provide a greater stability for the slide-plate 10 when compared to current plate assemblies, which generally have endplate thicknesses of approximately 0.5 inch. In addition, the increased thicknesses of the first endplate 42 and second endplate 44 will provide increased support to the pivotable arms 14.
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A method for replacing each old wear pad 46 of the slide-plate can be practiced using the present slide-plate assembly, best seen in
The above-identified method for the present slide-plate assembly is advantageous over current plate assemblies because only the wear pad 46 needs to be replaced, not the entire mid-plate. In addition, it is contemplated that in the present method, the fasteners 58 are easily accessible after assembly of the spike-pulling machine 12, so that replacement of the wear pads 46 can be easily accomplished in a time-effective manner. The present method is more cost-effective than current plate assemblies because only the wear pad 46 needs to be replaced, compared to the entire mid-plate in current plate assemblies.
While a particular embodiment of the present toggle slide-plate has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.
Number | Name | Date | Kind |
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2826446 | Hursh | Mar 1958 | A |
3066913 | Leeson | Dec 1962 | A |
3883118 | Miller | May 1975 | A |
4538793 | Dieringer et al. | Sep 1985 | A |
5253844 | Cotic et al. | Oct 1993 | A |
Number | Date | Country | |
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20070113752 A1 | May 2007 | US |