This disclosure relates to the field of machines for maintaining railroads, and in particular, to machines that remove railroad spikes embedded in railroad ties along rails of a railroad track.
Railroad spikes in railroad ties of a railroad track may need to be removed from time to time to enable railroad operators to maintain railroad tracks. Conventional railroad spike puller machines are configured to transit along railroad rails of a railroad track and are positionable over railroad spikes designated to be pulled. A typical railroad track includes a railroad rail supported by a tie plate, which is supported by a wooden railroad tie positioned transverse to the rail, where the tie plate and the rail are anchored to the railroad tie with one or more railroad spikes. When it becomes necessary to remove the railroad spikes to remove and replace, for example, the railroad rail or the railroad tie, spike pulling machines known in the art are configured to pull the railroad spike from the railroad tie. To remove the railroad spike, the spike pulling machine may be configured to grab or catch the head of the railroad spike and pull the railroad spike in a generally vertical motion.
However, prior spike pulling machines are not durable enough to withstand the rigors of pulling thousands of railroad spikes per day, every day. In addition, prior spike pulling machines are not configured to solve the problem of removing a railroad spike on one side of a rail when the other side of the rail has an obstruction, such as a horizontally-extending fastener on the opposite side of the rail for joining two adjacent rail segments together, a railroad switch, or a crossing, for example. Moreover, prior spike pulling machines are not configured to solve the problem of removing a railroad spike on one side of the rail using an independent motion from that on the other side of the rail. Further, prior spike pulling machines are not configured to solve the problem of removing a line spike and an anchor spike simultaneously, where the line spike is a railroad spike positioned along the rail to engage the base of the rail to anchor the rail to the railroad tie, and the anchor spike is a railroad spike positioned on the opposite side of the rail to anchor the tie plate to the railroad tie.
Consequently, there exists a need for an apparatus that solves these and other problems.
An embodiment of a spike puller workhead for pulling spikes from railroad ties is disclosed, comprising: (i) a frame; (ii) wheels coupled to the frame for rolling along a rail; (iii) a base carrier slidably coupled to the frame along a vertical axis; (iv) a puller cylinder coupled to the base carrier to cause the base carrier to slide along the vertical axis; (v) an inner puller arm including an inner puller proximal end and an inner puller distal end, wherein the inner puller proximal end is rotatably coupled to the base carrier about an inner longitudinal axis parallel to the rail, and wherein the inner puller distal end is configured for pulling inner spikes on or near the rail; (vi) an outer puller arm including an outer puller proximal end and an outer puller distal end, wherein the outer puller proximal end is rotatably coupled to the slide box about an outer longitudinal axis parallel to the rail, and wherein the outer distal end is configured to couple to an outer puller claw configured for pulling outer spikes along the rail; (vii) an inner puller claw cylinder configured to rotate the inner puller arm about the inner longitudinal axis to grasp the inner spikes along the rail; and (viii) an outer puller claw cylinder configured to rotate the outer puller arm about the outer longitudinal axis to grasp the outer spikes along the rail, wherein the inner puller claw cylinder is configured to rotate the inner puller arm independently of the outer puller claw cylinder rotating the outer puller arm.
The spike puller workhead may include vertical shafts that are coupled to the frame, where the base carrier may be slidably coupled to the frame via the vertical shafts. The puller cylinder may include a barrel and a rod, where the barrel may be coupled to the frame and the rod is coupled to the base carrier. The rod may be configured to: (a) actuate downward to an extended position to cause the inner puller arm and outer puller arm to descend toward the spikes on or near the rail; and (b) actuate upward to a retracted position to cause at least one of the inner puller arm and outer puller arm to pull an engaged spike from the ground while ascending.
The base carrier may define an inner housing and an outer housing, where the inner puller proximal end of the inner puller arm may be rotatably coupled to the base carrier within the inner housing, and where the outer puller proximal end of the outer puller arm may be rotatably coupled to the base carrier within the outer housing. The inner puller claw cylinder may include a barrel and a rod, the barrel may be coupled to the base carrier, and the rod may be coupled to the inner puller arm. The rod may be configured to retract to move the inner puller arm toward an inner spike. The outer puller claw cylinder may include a barrel and a rod, the barrel may be coupled to the base carrier, and the rod may be coupled to the outer puller arm. The rod may be configured to retract to move the outer puller arm toward an outer spike.
The spike puller workhead may include a spotting cylinder configured to couple the frame to a railroad car. The spotting cylinder may be configured to actuate to adjust respective longitudinal positions of the inner puller arm and the outer puller arm along the rail.
An embodiment of a spike puller workhead for pulling spikes from railroad ties is disclosed, comprising: (i) a frame; (ii) wheels coupled to the frame for rolling along a rail; (iii) a base carrier slidably coupled to the frame along a vertical axis, wherein the base carrier defines an inner housing and an outer housing; (iv) a puller linear actuator coupled to the base carrier to cause the base carrier to slide along the vertical axis; (v) an inner longitudinal linear actuator coupled to the inner housing of the slide box and configured to actuate along an inner longitudinal axis parallel to the rail; (vi) an inner carrier coupled to the inner longitudinal linear actuator to actuate along the inner longitudinal axis; (vii) an outer longitudinal linear actuator coupled to the outer housing of the slide box and configured to actuate along an outer longitudinal axis parallel to the rail; (viii) an outer carrier coupled to the outer longitudinal linear actuator to actuate along the outer longitudinal axis; (ix) an inner puller arm including an inner puller proximal end and an inner puller distal end, wherein the inner puller distal end is configured for pulling inner spikes along the rail, wherein the inner puller proximal end is pivotably coupled to the inner carrier about the inner longitudinal axis, and wherein actuation of inner carrier causes a position of the inner puller arm to be adjusted along the inner longitudinal axis; and (x) an outer puller arm including an outer puller proximal end and an outer puller distal end, wherein the outer puller distal end is configured for pulling outer spikes along the rail, wherein the outer puller proximal end is pivotably coupled to the outer carrier about the outer longitudinal axis, and wherein actuation of inner carrier causes a position of the outer puller arm to be adjusted along the outer longitudinal axis.
The inner longitudinal linear actuator may include: (a) a threaded rod coupled to the inner housing of the base carrier and extending along the inner longitudinal axis; and (b) a bushing threadably coupled to the threaded rod to travel along the inner longitudinal axis. The bushing may be configured to push the inner carrier along the inner longitudinal axis as the bushing travels along the threaded rod. The spike puller workhead may include at least one support shaft that is coupled to the inner housing of the base carrier and parallel to the threaded rod, and the inner carrier may be slidably coupled to the at least one support shaft to prevent the inner advancing block from pivoting about the inner longitudinal axis. The outer longitudinal linear actuator may include: (a) a threaded rod coupled to the outer housing of the base carrier and extending along the outer longitudinal axis; and (b) a bushing threadably coupled to the threaded rod to travel along the outer longitudinal axis. The bushing may be configured to push the outer carrier along the outer longitudinal axis as the bushing travels along the threaded rod. The spike puller workhead may include at least one support shaft that is coupled to the outer housing of the base carrier and parallel to the threaded rod, and the outer carrier may be slidably coupled to the at least one support shaft to prevent the outer carrier from pivoting about the outer longitudinal axis.
Another embodiment of a spike puller workhead for pulling spikes from railroad ties is disclosed, comprising: (i) a frame; (ii) wheels coupled to the frame for rolling along a rail; (iii) a base carrier slidably coupled to the frame along a vertical axis, wherein the base carrier defines an inner housing and an outer housing; (iv) a puller linear actuator coupled to the base carrier and configured to cause the base carrier to slide along the vertical axis; (v) an inner longitudinal linear actuator coupled to the inner housing of the base carrier and configured to actuate along an inner longitudinal axis parallel to the rail; (vi) an inner carrier coupled to the inner longitudinal linear actuator to actuate along the inner longitudinal axis; (vii) an outer longitudinal linear actuator coupled to the outer housing of the base carrier and configured to actuate along an outer longitudinal axis parallel to the rail; (viii) an outer carrier coupled to the outer longitudinal linear actuator to actuate along the outer longitudinal axis; (ix) an inner puller arm including an inner puller proximal end and an inner puller distal end, wherein the inner distal end is configured for pulling inner spikes on or near the rail, wherein the inner proximal end is pivotably coupled to the inner carrier about the inner longitudinal axis, and wherein actuation of inner carrier causes a position of the inner puller arm to be adjusted along the inner longitudinal axis; (x) an outer puller arm including an outer puller proximal end and an outer puller distal end, wherein the outer distal end is configured for pulling outer spikes on or near the rail, wherein the outer proximal end is pivotably coupled to the outer carrier about the outer longitudinal axis, and wherein actuation of inner carrier causes a position of the outer puller arm to be adjusted along the outer longitudinal axis; (xii) an inner puller claw linear actuator configured to pivot the inner puller arm about the inner longitudinal axis to grasp the inner spikes on or near the rail; and (xiii) an outer puller claw linear actuator configured to pivot the outer puller arm about the outer longitudinal axis to grasp the outer spikes on or near the rail, wherein the inner puller claw linear actuator is configured to pivot the inner puller arm independently of the outer puller claw linear actuator pivoting the outer puller arm.
Each of the inner puller claw linear actuator and the outer puller claw linear actuator may include a housing and a rod, the housing of the inner puller claw linear actuator may be coupled to the inner advancing block, and the rod of the inner puller claw linear actuator may be coupled to the inner puller arm. The housing of the outer puller claw linear actuator may be coupled to the outer advancing block, and the rod of the outer puller claw linear actuator may be coupled to the outer puller arm.
For a better understanding of the features described in this disclosure, reference may be made to embodiments shown in the drawings. The components in the drawings are not necessarily to scale, and related elements may be omitted so as to emphasize and clearly illustrate the novel features described herein. In addition, system components can be variously arranged, as known in the art. In the figures, like referenced numerals may refer to like parts throughout the different figures unless otherwise specified.
While the features, methods, devices, and systems described herein may be embodied in various forms, there are shown in the drawings, and will hereinafter be described, some exemplary and non-limiting embodiments. Not all of the depicted components described in this disclosure may be required, however, and some implementations may include additional, different, or fewer components from those expressly described in this disclosure. Variations in the arrangement and type of the components may be made without departing from the spirit or scope of the claims as set forth herein. Thus, it should be appreciated that any of the features of an embodiment discussed with reference to the figures herein may be combined with or substituted for features discussed in connection with other embodiments in this disclosure.
Turning to the figures, there are shown various embodiments of a workhead apparatus for pulling railroad spikes from a railroad tie. Each of the embodiments of the workhead apparatus includes two claw or puller arms, each of which includes a replaceable and/or interchangeable puller claw tool mounted thereon configured to engage with a head of a railroad spike to pull the railroad spike from the railroad tie. Each claw or puller arm is configured with, and may be articulated by, its own, dedicated actuator, such as a hydraulic cylinder, which may be electronically controlled to operate by a remote operator. The operator can choose to operate both claw or puller arms simultaneously, each individual claw or puller arm independently, or neither of the claw arms by, for example, selecting an appropriate switch or operating control from, for example, within the cab of the rail machine. The independent movement of the claw or puller arms allow the operator to avoid potential hazards during the work cycle, such as unfavorable ballast conditions, rail joint bars and bolts, crossings, switches and frogs, thereby preventing damage to the puller claw tool or workhead apparatus in general. Unlike prior railroad spike pulling mechanisms that are unable to pull a spike on one side of the rail when an obstruction blocks or interferes the travel of a claw or puller arm on the opposite side of the rail, the claw or puller arm of the workhead apparatus of the instant disclosure that is positioned on the side of the rail that is opposite the hazard is still able to pull the railroad spike. This functionality is made possible by the independently selectable movement of the claw or puller arms of the instant workhead apparatus, and/or due to the option of longitudinally staggering the claw or puller arms with respect to one another. In addition, the workhead apparatus of the instant disclosure is configured to allow pulling of a line spike (defined as a railroad spike whose head engages the base of the rail) and an anchor spike (defined as any other railroad spike that secures a tie plate to the railroad tie while not engaging the rail) positioned on opposite sides of a rail either simultaneously or independently as desired by the operator. This functionality is of considerable value to railroad operators because the position of a line spike relative to a rail and an anchor spike relative to the same side of the rail are quite different from one another. Consequently, pulling a line spike on one side of the rail simultaneously or independently of an anchor spike on the opposite side of the rail poses challenges that the workhead apparatus of the instant disclosure overcomes. Moreover, the workhead apparatus of the instant disclosure overcomes the challenge of obstacles or hazards that may otherwise interfere with pulling line spikes and anchor spikes on opposite sides of a rail.
For example, as shown in
In addition, at least one embodiment of the workhead apparatus of the instant disclosure is configured with a robust, dual-shaft pattern advancing block 22, which enables the claw or puller arm 29 on one side of the rail to be positioned in a longitudinally staggered relationship with the claw or puller arm 29 on the opposite side of the rail, as shown in
Workhead apparatus 100 of the instant disclosure is configured with subframe 1 to mount the apparatus to a rail machine and to act as a mount frame and datum for other components of the workhead apparatus 100, a pair of horizontally spaced apart spotting shafts 5 to allow the vertical slide carrier 16 to translate horizontally along the rail for alignment over designated spikes to be pulled, a pair of vertically spaced apart shafts 10 to allow the vertical slide carrier 16 to move up and down to effect a spike pulling operation, a pair of opposed puller arms 29 for engaging with spikes to be pulled via a replaceable puller tool mounted on the end of each puller arm 29, a pair of horizontal spaced apart advancing shafts 17 connected to a respective advancing block 22 and puller arm 29 to selective translate the puller arm 29 longitudinally along the rail via acme threaded rod 21 (or in other embodiments, any type of linear actuator, whether electronically controlled or manually operated), actuator 32 (which may be hydraulically, pneumatically or otherwise actuated) to articulate a respective puller arm 29 outwardly and inwardly to engage a designated spike to be pulled, spike puller A-frame 48 connected to the subframe 1 to resist and/or apply pulling forces to a spike being pulled, and actuator 60 to cause vertical slide carrier 16 to move up and down to effect a spike pulling operation. Workhead apparatus 100 additionally includes various features and components shown in the figures for locking the vertical slide carrier 16 in a transport position to allow the workhead apparatus 100 to be transported safely. These and other features, components, and functionality are described in more detail below.
Turning to
Workhead apparatus 100 includes vertical slide carrier 16, A-frame 48, and vertical pulling actuator 60—all of which are configured to impart and/or manage repetitive spike pulling loads, sometimes thousands of times per day, every work day. In the embodiments shown in the figures, actuator 60 is configured as a hydraulic cylinder. In other embodiments, actuator 60 may be any type of actuator, including electric, pneumatic, or otherwise, to produce vertical motion of slide carrier 16.
A-frame 48 includes a pair of wheels 55 to position the workhead apparatus 100 onto a designated railroad rail. A-frame 48 is configured to support slide carrier 16 (and all components supported by slide carrier 16), which is mounted to and configured to traverse and slide upon a pair of parallel, opposed vertical shafts 10 via sleeves or bushings 7 (see
Slide carrier 16 cantileverly extends from vertical shafts 10 in a direction opposite to side 1a of subframe 1. Slide carrier 16 includes a pair of parallel, opposed side walls 16a and transverse end wall 16b connected to the side walls 16a. Side walls 16a extend from a pair of opposed, parallel, tubular, vertical receivers 16c that connect to and are configured to traverse and slide upon the respective vertical shafts 10 via sleeves or bushings 7 housed in the receivers 16c. Slide carrier 16 is configured to support inner and outer puller arms 29, inner and outer advancing blocks 22, inner and outer parallel, opposed advancing shafts 17, inner and outer advancing rods 21, and inner and outer puller arm actuators 32.
Respective advancing shafts 17 and advancing rods 21 are configured to horizontally extend from one side wall 16a to the other side wall 16a. Respective inner and outer advancing blocks 22 are configured to traverse and slide upon respective inner and outer upper advancing shafts 17 via bushings 24. Respective advancing blocks 22 are also configured to attach to respective inner and outer advancing rods 21 configured with acme screw threads for causing the respective advancing blocks 22 to traverse laterally via bushings 25 to locations anywhere between side walls 16a when the advancing rods 21 are manually rotated and/or set by an operator. In other embodiments, a linear actuator and/or rotary actuator, or any other actuator configured to produce linear movement of advancing blocks 22, may be substituted for or used in conjunction with advancing rods 21. In such other embodiments, the operator may remotely command a rotary actuator, for example, to rotate a respective one of the inner and outer advancing rods 21, thereby causing lateral translation of the respective inner or outer advancing block 22 along respective advancing shafts 17 to the position desired by the operator. In the embodiment shown in
Respective inner and outer puller arms 29 extend downwardly from respective inner and outer lower advancing shafts 17b via bushings 30. Inner puller arm 29 is configured to extend downwardly and inwardly and then outwardly in an arc, while outer puller arm 29 is configured to extend downwardly and outwardly and then inwardly in an arc. Respective upper ends (i.e., the proximal ends) of inner and outer puller arms 29 lie between opposed side walls 22a of respective inner and outer advancing blocks 22. The upper ends (i.e., the proximal ends) of respective inner and outer puller arm actuators 32 are connected to respective inner and outer clevis pins 35, each of which extending from one side wall 22a to the other side wall 22a of respective inner and outer advancing blocks 22. The lower ends (i.e., the distal ends) of respective inner and outer puller arm actuators 32 are pivotally connected to respective inner and outer clevis pins 34, each of which extending from one side wall 29a to the opposite side wall 29a of respective inner and outer puller arms 29. In the embodiments shown in the figures, actuators 32 are configured as hydraulic cylinders. In other embodiments, actuators 32 may be any type of actuator, including electric, pneumatic, or otherwise, that impart a force upon puller arms 29.
Upper end of actuator 60 is configured to attach to upper end of A-frame 48 via clevis pin 61, and lower end of actuator 60 is configured to attach to upper end of slide carrier 16 via clevis pin 62 that extends to/from respective clevis walls 16d.
To control the extent of upper and lower vertical movement of slide carrier 16 for a spike pulling operation, various embodiments of workhead apparatus 100 may include upper and lower proximity switches 71. Upper and lower proximity switches 71 are held in a vertical relationship with one another via vertically oriented bracket 65. The vertical positions of the upper and lower proximity switches 71, including the vertical distance between them, may vary as determined by the operator according to the height of the rail relative to the heads of the spikes to be pulled. In some embodiments (see, e.g.,
In at least some embodiments (see, e.g.,
Proximity switch trigger bracket 70, which is mounted on slide carrier 16, is configured to trigger activation of the upper and lower proximity switches 71. When trigger bracket 70 moves proximate to the upper proximity switch 71, actuator 60 is commanded to stop retracting. When trigger bracket 70 moves proximate to the lower proximity switch 71, actuator 60 is commanded to stop extending.
Workhead apparatus 100 includes features to enable the apparatus to be safely transported when not in use. For example, workhead apparatus 100 includes a lock-up mechanism to restrain slide carrier 16 from moving during transport. In the embodiments shown in the figures, the lock-up mechanism includes an upward slide carrier restraint system mounted on respective lateral sides of A-frame 48, and an downward slide carrier restraint system mounted on side 1b of subframe 1. For each respective lateral side of A-frame 48, the upward slide carrier restraint system includes a lock-up bracket 80 mounted to A-frame 48, lock-up actuator 83, lock-up pivot bracket 81, and lock-up horizontal pin 82. Upper end of lock-up actuator 83 is connected to an upper end of lock-up bracket 80. Lower end of lock-up cylinder 83 is connected to upper end of pivot bracket 81. Lower end of pivot bracket 81 is pivotally connected to lower end of lock-up bracket 80. The downward slide carrier restraint system includes lock-up actuator 99a coupled to lock-up pivot bracket 99b, which is configured to engage with lock-up post 99c (see
The lock-up mechanism of workhead apparatus 100 is in slide carrier transport mode with lock-up actuators 83,99a in their respective retracted positions. Conversely, the lock-up mechanism of workhead apparatus 100 is in slide carrier operational mode with lock-up actuators 83,99a in their respective extended positions.
As described above, workhead apparatus 100 is configured to pull railroad spikes from locations on both sides (inner and outer) of a given rail. Workhead apparatus 100 is configured with a puller arm 29 on both sides of a single rail, where each of the puller arms 29 may be operated independently of one another. Independent operation of puller arms 29 enables line spikes and anchor spikes on respective sides of the rail to be pulled simultaneously or independently of one another regardless of whether the spikes are in staggered relationship with one another.
Workhead apparatus 100 is configured to be operated by a single operator. Multiple workhead apparatuses 100 may be arranged on a machine that traverses a railroad track to enable one or more operators to pull railroad spikes on adjacent parallel rails of a railroad track.
As shown in the figures, workhead apparatus 100 is configured to move longitudinally along the rail to permit an operator to “spot” the workhead apparatus 100 over a desired tie plate and over a desired one or more railroad spikes to be pulled. More specifically, as shown in
To operate workhead apparatus 100, there are adjustments that need to be made prior to starting a spike pulling operation, namely to the upper proximity switch 71, the lower proximity switch 71, the pattern or lateral positioning of outside puller arm 29, and the pattern or positioning of inner puller arm 29. The upper proximity switch 71 tells the actuator 32 when to open. This releases the spike and returns the puller arm 29 to the ready position. The lower proximity switch tells the actuator 32 when to squeeze and pull. The squeeze and pull sequence is part of the logic of the machine, but the lower proximity switch 71 is the trigger to tell it when to start the squeeze and pull sequence. The lower limit (i.e., the position of the lower proximity switch 71) is determined by the operator according to the height of the rail and the position of the claw tools positioned on the respective distal ends of the inner and outer puller arms 29. The lower proximity switch 71 should be set at a height to permit the inner and outer claw tools to slide under the head of the spike. If the lower limit is too low, it will hit the edge of the tie plate and damage the tools, tie or tie plate. If the lower limit is too high, it will miss the spike. The upper limit (i.e., the position of the upper proximity switch 71) should allow the spike to be fully removed from the tie plate. If the upper limit is too high, operational cycle time may be wasted. If the upper limit is too low, the spike will hang up in the hole and another cycle will need to be performed or the upper limit will have to be adjusted to remove the spike fully. In addition, the inner and outer adjusting advancing rods 21 comprising, for example, acme threads, can be rotated manually or remotely by an operator as described above to set the pattern of the inner and outer puller arms 29. As shown in the figures, a hex pin on the end of each respective advancing rods 21 enable an operator to rotate the advancing rods 21 with a wrench. In other embodiments, as described above, a bi-directional rotary actuator 21a may be used to set the pattern. The pattern is adjusted based on the particular tie plate configuration of interest or the specific spikes spacing/configuration that are designated to be pulled.
Turning to
At step 1006, the operator determines whether the upper and lower proximity switches 71 are set at the proper height to establish the upper and lower travel limits of the slide carrier 16. If the proximity switches 71 require repositioning, the operator does so at step 1008 by moving the proximity switches 71 as described above. If not, the process moves to step 1010.
At step 1010, the operator determines whether the inner and outer puller arms 29 are in the proper lateral position to match the spike pattern in the tie plate. If the lateral position of one or both puller arms 29 requires repositioning, then at step 1012 the operator may move the desired inner and/or outer advancing block 22 laterally within the slide carrier 16 along advancing shafts 17 by rotating advancing rods 21 to create the required offset between the inner and outer puller arms 29 to match the pattern of the spikes to be pulled.
At step 1014, the operator moves work train into position so that workhead apparatus 100 is generally positioned over a desired railroad tie having spikes to be pulled. At step 1016, the operator determines whether any fine adjustments to the lateral position of the workhead apparatus 100 are required to align the puller arms 29 over the inner and outer spikes to be pulled. If yes, then at step 1018, the operator actuates spotting cylinder 95, as shown in
At step 1020, as shown in
At step 1022, after reaching the lower limit set by lower proximity switch 71, actuator 60 ceases to further extend and one or both of the inner and outer actuators 32 are commanded, either automatically via control system logic or manually by remote operator triggering, to retract. At step 1024 and as shown in
At step 1026 and as shown in
At step 1030, the operator may move the work train to another railroad tie to repeat the process of pulling spikes using workhead apparatus 100.
Any process descriptions or blocks in the figures should be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps in the process, and alternate implementations are included within the scope of the embodiments described herein, in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those having ordinary skill in the art.
The embodiments described herein are possible examples of implementations and are merely set forth for a clear understanding of the principles of the features described herein. Many variations and modifications may be made to the above-described embodiment(s) without substantially departing from the spirit and principles of the techniques, processes, devices, and systems described herein. All such modifications are intended to be included herein within the scope of this disclosure and protected by the following claims.
This application is a continuation of U.S. patent application Ser. No. 17/647,522 filed Jan. 10, 2022, which is a continuation of U.S. patent application Ser. No. 16/399,039, filed on Apr. 30, 2019, which claims the benefit of U.S. Provisional Patent Application No. 62/832,874, filed on Apr. 11, 2019. These applications are incorporated by reference herein in their entirety.
Number | Date | Country | |
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62832874 | Apr 2019 | US |
Number | Date | Country | |
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Parent | 17647522 | Jan 2022 | US |
Child | 18193000 | US | |
Parent | 16399039 | Apr 2019 | US |
Child | 17647522 | US |