Patent Application
20220266626
The present invention relates to the railway industry and, more particularly, to a two-piece rail wheel assembly for use on rail cars.
Conventional rail wheels comprise a single component that is secured to an axle of a rail car utilizing an interference press fit at the wheel/axle interface. The process of securing the wheel to the axle requires a specialized press capable of forces over 100 tons (e.g., a specialized 400-ton press) to remove and attach the wheel. The operation requires highly-specialized knowledge by the press operators to assure proper and safe fit of the wheel to the axle. A typical interference may be 0.004-0.006 inches. This press fit design has a high risk of damage to both the wheel during installation and removal. Therefore, any method to replace a wheel while eliminating removal of press fit components would be of great benefit to the vehicle operator.
In order to replace and/or repair a conventional rail wheel, the entire truck must be removed from the rail car and the axle/wheel assembly must be removed from the truck. Then it is possible to remove the wheel from the axle using press equipment. Indeed, as the current state of the art requires a large, factory-based press machine, it is not possible to change wheels in the field or on the rail. Instead, the current state of the art requires changing the wheels at the factory where the specialized press machine is available. As a result, the process to replace or repair a wheel of a rail car requires significant time out of service. Additionally, because conventional rail wheels comprise a single component, any damage to the wheel requires removing and potentially replacing the entire wheel in order to place the train back in service.
A wheel design that does not require removing and disassembling the truck (and the frame that holds the axles) when changing a wheel and that allows less than the entirety of the rail wheel to be removed and replaced when a wheel is damaged would be a significant improvement.
Aspects of this disclosure relate to a rail wheel assembly that allows a tire to be replaced without requiring disassembly of the rail vehicle or removal of components directly attached to the axle. In various embodiments, the rail wheel assembly may comprise a center wheel hub and a tire configured to engage a rail. The center wheel hub may be attached to an axle of a railway vehicle with an interference press fit and include an outward facing stepped interface located at an outer edge of the center hub. The tire may include an inward facing stepped interface located at an inner edge of the tire. In various embodiments, the outward facing stepped interface of the center hub may be configured to receive the inward facing stepped interface of the tire. Each of the outward facing stepped interface on the center wheel hub and the inward facing stepped interface of the tire may include a plurality of holes configured to receive bolts configured to secure the tire to the rail wheel assembly via the center wheel hub. In various embodiments, the outward facing stepped interface of the center hub interfaces directly with the inward facing stepped interface of the tire (i.e., without any components between the outward facing stepped interface and the inward facing stepped interface).
The two-piece rail wheel assembly described herein may serve a replacement for a one-piece solid steel wheel conventionally used on rail cars and other rail vehicles. Unlike conventional rail car wheels, however, the tire of the rail wheel assembly described herein may be removed and replaced without requiring removal of any of the components affixed directly to the axle. For example, in an in-board bearing configuration, a tire may be replaced on the rail wheel assembly described herein by simply lifting the rail car up, unbolting the tire from the center hub, sliding the tire off the axle, sliding a new tire on, bolting the new tire to the center hub, and lowering the rail car down onto the track. Unlike the process for removing conventional rail wheels, this process does not require using a press machine, detaching the truck assembly from the rail car, or detaching the wheelset (which includes at least the axle, gearbox, bearings, and wheels) from the truck. In order to replace a tire in an out-board bearing configuration using the rail wheel assembly described herein, the truck assembly will need to be detached from the rail car, and the wheelset removed from the truck assembly. However, unlike the process for removing conventional rail wheels in out-board bearing configurations, the rail wheel assembly described herein eliminates the need to use a press machine or remove any other components of the wheelset from axle, including the bearings, brake discs, gearbox, grounding system, and/or any other components of the wheelset. As such, the likelihood of these components being damaged or these components needing to be requalified or replaced is reduced.
These and other objects, features, and characteristics of the invention disclosed herein will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
The present invention is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements and in which:
These drawings are provided for purposes of illustration only and merely depict typical or example embodiments. These drawings are provided to facilitate the reader's understanding and shall not be considered limiting of the breadth, scope, or applicability of the disclosure. For clarity and ease of illustration, these drawings are not necessarily drawn to scale.
In the following description of various examples of the invention, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration various example structures, systems, and steps in which aspects of the invention may be practiced. It is to be understood that other specific arrangements of parts, structures, example devices, systems, and steps may be utilized, and structural and functional modifications may be made without departing from the scope of the present invention. Also, while the terms “top,” “bottom,” “front,” “back,” “side,” and the like may be used in this specification to describe various example features and elements of the invention, these terms are used herein as a matter of convenience, e.g., based on the example orientations shown in the figures. Nothing in this specification should be construed as requiring a specific three-dimensional orientation of structures in order to fall within the scope of this invention.
The invention described herein relates to a two-piece railroad wheel assembly that allows a tire to be replaced without requiring disassembly of the rail vehicle or removal of components directly attached to the axle. While this wheel assembly is designed specifically for rail wheels on rail cars, this wheel assembly design and the corresponding methods described herein may be utilized with any transit system or railway vehicle that utilizes press-fit wheel/axle assemblies.
In various embodiments, front axial interface 124 of center hub 120 directly interfaces with rear axial interface 134 of tire 130. In other words, front axial interface 124 of center hub 120 is flush against rear axial interface 134 of tire 130. Any components, material, or space between front axial interface 124 of center hub 120 and rear axial interface 134 of tire 130 would cause tire 130 to move relative to center hub 120, which would reduce the load carrying capacity of two-piece railroad wheel assembly 100 and the speed with which two-piece railroad wheel assembly 100 would be able to travel. For example, any components between center hub 120 and tire 130 would reduce the load carrying capacity and maximum speed of two-piece railroad wheel assembly 100 such that it would be suitable for use with freight cars or heavier passenger cars. As such, in various embodiments, center hub 120 interfaces directly with tire 130 (i.e., without any components between front axial interface 124 and rear axial interface 134).
In some embodiments, stepped interface 140 may include a taper on corresponding horizontal portions of front axial interface 124 and rear axial interface 134 to ease mounting of tire 130 onto center hub 120. In some embodiments, corrosion prevention features may be utilized in stepped interface 140 (i.e., between front axial interface 124 and rear axial interface 134). For example, rust prevention features may be utilized in stepped interface 140 (i.e., between front axial interface 124 and rear axial interface 134).
In various embodiments, the plurality of holes 126 on front axial interface 124 may align with the plurality of holes 136 on rear axial interface 134 to form a plurality of holes via which tire 130 may be bolted to center hub 120. For example, bolts 150 may be inserted into the plurality of holes 126, 136 and secured via nuts 160 on the opposite side to affix or “lock” tire 130 to axle 110 via center hub 120. In various embodiments, bolts 150 may comprise screws, pins, and/or any other mechanical fastener that is known and used in the art, and nuts 160 may comprise any corresponding component known and used in the art that is configured to receive bolts 150. In various embodiments, the nuts 160 may comprise self-contained locking nuts. In some embodiments, the nuts 160 may include multiple locking features for redundancy. For example, one or more individual nuts 160 may include slits in the side of the nuts 160 (one on each side) that force the nuts to bind on themselves when removed. The top part above the slit will not want to move where the part below the slit does. In some embodiments, the nuts 160 may include slits on each side of the nut that run the entire way through the nut. In some embodiments, the nuts 160 may be used in connection with a Belleville-style washer. A Belleville-style washer is a type of conical spring washer that spreads out as you tighten it and acts as a spring force to further lock bolts 150 in place using nuts 160. In some embodiments, the combination of bolts 150 and nuts 160 may include a custom fastener specifically designed for use in two-piece railroad wheel assembly 100. For example, in some embodiments, a no mare fastener may be used to further secure tire 130 to center hub 120 without marking either the tire 130 or center hub 120.
In various embodiments, a plurality of bolts 150 may be utilized to secure tire 130 to center hub 120 via the plurality of holes 126, 136. The number of bolts 150 may range from two bolts to ten or even more bolts. In various embodiments, the plurality of holes 126, 136 may be geometrically and even spaced around axle 110. For example, twelve bolts 150 evenly spaced around the wheel may be utilized to secure tire 130 to center hub 120 via the plurality of holes 126, 136.
In various embodiments, bolts 150 may be configured to provide only clamping force between tire 130 and center hub 120 and not carry shear forces perpendicular to the bolt centerline. In some embodiments, one or more alignment/shear pins may be utilized in conjunction with bolts 150 and nuts 160 to secure tire 130 to center hub 120. For example, in an example embodiment, one or more of the plurality of bolts 150 may be replaced with alignment/shear pins. The alignment/shear pins may be utilized to carry loads between center hub 120 and tire 130 to avoid shear forces on the bolts.
In some embodiments, two-piece railroad wheel assembly 100 may include one or more bolt retaining plates (also interchangeably referred to herein as “bolt retainers”) positioned on the rear (or interior) side of center hub 120 and configured to hold two or more of bolts 150 in place. For example,
Utilizing a two-piece railroad wheel assembly 100 comprising a center hub 120 and a tire 130 may provide many benefits over prior art designs. For example, two-piece railroad wheel assembly 100 may allow replacement of tire 130 without the need for major disassembly of the rail vehicle. For example, in order to replace and/or repair a conventional rail wheel, the entire rail vehicle must first be moved to a maintenance facility and then lifted with a crane in order to detach the truck assembly. The truck assembly must then be moved to a maintenance stand where the wheelset (which includes the axle, gearbox, bearings, and wheels) is detached from the truck. As described herein, removing a conventional rail wheel requires the use of a large, factory-based press machine that cannot be used to remove the wheel if the wheelset is attached to the truck. The wheelset must then be moved to a wheel press facility wherein the wheels, journal bearings, brake discs, and gearbox are removed from the axle. As described herein, the components of conventional rail wheels are mounted to the axle with interference press fits. As such, disassembly places all the components of the wheelset at risk of damage.
Once disassembled, various components must be requalified or replaced per Association of American Railroads (AAR) requirements depending on whether the rail car has a in-board or out-board bearing configuration. Trucks are attached to axles at journal bearings. In an in-board bearing configuration, the journal bearings are located inside the wheels. In an out-board bearing configuration, the journal bearings are located outside the wheels. Because removing conventional rail wheels requires use of a press machine, and press machines require the wheelset be removed from the truck, the wheelset must be removed from the truck to replace a conventional rail wheel regardless of whether it is in an in-board or out-board bearing configuration. In an out-board bearing configuration (in which the bearing is located outside the wheels), the bearings must also be removed because conventional rail wheels cannot be slid over the bearing. According to AAR Manual of Standards and Recommended Practices, Section G-II, Sub-Section 1.1.9, when a journal bearing is removed from an axle, the axle must be wet magnetic particle tested prior to remounting a bearing. AAR Manual of Standards and Recommended Practices, Section G-II, Sub-Section 1.8.1.2.4 further requires that any journal bearing that is removed from an axle for any reason be sent for reconditioning or replaced with a new bearing. As such, when removing a conventional rail wheel from an out-board bearing configuration (which is more common for freight cars and heavier passenger cars), the axles must also be requalified dimensionally and by magnetic particle inspection, and the bearings must be requalified or replaced. In some instances, the brake disc may also need to be requalified or replaced, and the gearbox may need to be rebuilt. Only once these components have been requalified, replaced, and/or rebuilt can the wheelset be reassembled with new wheels.
In order to reassemble the wheelset with new wheels, the wheels, journal bearings, brake discs, and gearbox must all be press fit on the axle. Similar to disassembly, reassembly of these interference fit components places each component at risk of damage. The reassembled wheelset must then be moved to a truck maintenance stand where the truck is rebuilt before being replaced under the vehicle. Before being replaced under the vehicle, however, the same extensive process performed for one wheelset must also be performed on its mate. Per AAR Manual of Standards and Recommended Practices, Section G-II, Sub-Section 1.4.7.3, any time a single wheel is dismounted from an axle, it's mate must also be dismounted regardless of condition.
The process required to replace and/or repair a conventional rail wheel is both labor, cost, and time-intensive. Indeed, in addition to requiring a large, factory-based press machine and posing increased risk of damage to the wheelset and its components, the process to replace or repair a wheel of a rail car also requires significant time out of service. Unlike the labor, cost, and time-intensive process required to replace a conventional rail wheel, replacing tire 130 of two-piece railroad wheel assembly 100 does not require even removing or disassembling the truck assembly when two-piece railroad wheel assembly 100 is utilized in an in-board bearing configuration.
When used in an out-board bearing configuration, the process to replace tire 130 of two-piece railroad wheel assembly 100 also represents an improvement over the process to replace a conventional rail wheel in the same configuration.
Accordingly, in both in-board and out-board bearing configurations, two-piece railroad wheel assembly 100 represents an improvement over conventional rail wheels. Two-piece railroad wheel assembly 100 does not require special tools to remove or replace the wear surface on the wheel (i.e., tire 130). Indeed, the large hydraulic press machine required to change a conventional rail wheel is not needed to change tire 130. Two-piece railroad wheel assembly 100 also eliminates the need to remove certain components when removing and replacing tire 130, including any components directly attached to axle 110. As such, the risk of damage to axle 110 when replacing a wheel is reduced compared to common practices for replacing conventional interference press fit wheels. Indeed, when removing a conventional rail wheel, the axle itself is frequently gauged in the process, which often requires replacing the axle. By reducing the risk of damage to axle 110 and other components affixed to axle 110, the two-piece railroad wheel assembly described herein reduces the number of scraped axles and other components, resulting in less steel consumed each time the wear surface of the wheel is renewed, which is good for the environment as it uses less energy to manufacture and machine. Also, as described above, if any components of a truck are removed from an axle (e.g., pressed on wheel, bearing, brake, or gearbox), the axle and bearings must be fully requalified per Association of American Railroads (AAR) requirements. For example, as provided above, AAR Manual of Standards and Recommended Practices, Section G-II, Sub-Section 1.8.1.2.4 currently states that if a journal bearing is removed from an axle for any reason, it must be sent for reconditioning or replaced with a new bearing. However, bearings have a performance life upwards of 5 times the life of a wheel. Thus, by allowing a wheel to be changed without having to recondition or replace bearings or other components, two-piece railroad wheel assembly 100 represent a significant operating cost advantage compared to prior art wheel designs by reducing labor cost, as well as by reducing the time the rail car spends out of service when replacing worn or damaged wheels.
It is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth herein. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It should be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention.
While the preferred embodiments of the invention have been shown and described, one skilled in the relevant art will recognize that numerous variations and modifications may be made to the examples described above without departing from the scope of the present disclosure. Thus, the spirit of the invention should be construed broadly as set forth in the appended claims.
This application claims priority to U.S. Provisional Patent Application No. 63/152,041, filed Feb. 22, 2021, the content of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63152041 | Feb 2021 | US |
