Patent Publication Number: US-2023163507-A1

Title: Slidable nested conductors

Description:
TECHNICAL FIELD 
     The present disclosure relates to a system used to provide electrical power to an electrically powered load or work machine. More specifically, the present disclosure relates to a conductive rod for an electrically powered work machine, whereby the conductive rod is extendable and retractable along a length of the conductive rod to maintain an electrical and/or physical connection with a roadside power source and the work machine using the conductive rod. 
     BACKGROUND 
     Heavy work machines, such as earth-moving vehicles or hauling trucks, require significant power to carry out their functions. The machines themselves can be of substantial weight, and their loads require large amounts of power to move. Diesel engines typically provide that power, but they can have disadvantages. For instance, in some implementations, heavy work machines may need to travel large distances through rugged terrain. At a remote mining site, for example, groups of these machines are often employed to ferry extreme loads along roadways, or haul routes, extending between various locations within the mining site. Supplies of diesel fuel may be far away from such locations or not easily delivered to such locations. In addition, the groups of diesel machines can generate significant pollution. 
     Electrical power has been used to supplement these diesel engines while the work machines move. In some environments, the electrical power is delivered from wires over the haul route to a pantograph on the work machine as the machine travels the haul route, as in a cable car. But overhead wires cannot reliably provide sufficient electrical energy to power a heavy work machine during long movements. Nor can the overhead delivery provide enough current to charge backup batteries for an electric machine at the same time. In addition, connection with overhead wires tolerates only small lateral movements by the vehicle before arcing or disconnection occurs. As a result, electrical power provided through overhead wires typically supplements, rather than replaces, power generated by diesel engines in heavy work machines. 
     In some environments, such as mine sites or other worksites in which the haul routes or other paths traveled by the work machines tend to be relatively non-linear, such overhead wires may be replaced by a power rail positioned adjacent to haul route. Establishing an electrical connection with a power rail can require precise movements of a conductor from a heavy work machine, however, and maintaining an electrical connection with a power rail while a heavy work machine moves can be particularly challenging. In locations such as a mining site, the haul route may be uneven, hilly, and pocked. These variations may lead to irregular movements by the machine or unexpected changes in position by the power rail, causing the machine to disconnect from the rail. Steering deviations for the heavy work machine could also disrupt the connection of the machine with the power rail, detracting from the value of rail-based delivery of electrical power. 
     One approach for providing electrical power to a vehicle through a rigid conductor is described in U.S. Pat. App. Pub. No. 2017/0106767A1 (“the ‘767 application”). The ‘767 application describes a vehicle power supply method in which a charging arm of fixed length is deployed transversely from a vehicle to contact a power supplying apparatus. To reach the power supplying apparatus with the arm, a device is caused to slide along the side of the vehicle, which forces a damper unit to push the arm around an axis of rotation and displace its end outwardly from the vehicle. 
     A rotating arm of fixed length, as described in the ‘767 application, however, has a limited reach from the side of the vehicle, which limits the lateral movement available in steering. Moreover, support for the arm is essentially limited to one end of the arm at the axis of rotation, which may be inadequate to support a long arm of substantial weight. Such a mechanism would also be prone to failure when used in harsh conditions such as mine sites, paving sites, and construction sites. As a result, the system described in the ‘767 application is not desirable for heavy work machines having high electrical power loads or operating in environments in which the machines may substantially deviate along their paths when moving. 
     Examples of the present disclosure are directed to overcoming deficiencies of such systems. 
     SUMMARY 
     In one aspect of the presently disclosed subject matter, a conductor rod includes an arm section extending along a longitudinal axis of the conductor rod section and a barrel section extending the longitudinal axis of the conductor rod. The arm section includes a first piston conductor affixed to a connector assembly at a first end of the conductor rod, the first piston conductor extending along the longitudinal axis having a first inner diameter and a first outer diameter, a second piston conductor affixed to the connector assembly at the first end, the second piston conductor extending along the longitudinal axis having a second inner diameter greater than the first outer diameter and a second outer diameter, and an arm affixed to the connector assembly at the first end, the arm extending along the longitudinal axis having a third inner diameter greater than the second outer diameter and a third outer diameter. The barrel section includes a first cylinder conductor affixed to a head-end interface at a second end of the conductor rod, the first cylinder conductor extending along the longitudinal axis having a fourth outer diameter and a fourth inner, wherein the fourth inner diameter is greater than the first outer diameter of the first piston conductor, wherein a first inner surface of the first cylinder conductor is slidably engaged to a first outer surface of the first piston conductor at a first conducting interface, a second cylinder conductor affixed to the head-end interface at the second end, the second cylinder conductor extending along the longitudinal axis having a fifth outer diameter less than the second inner diameter of the second piston conductor and greater than the fourth outer diameter of the first cylinder conductor, wherein a second outer surface of the second cylinder conductor is slidably engaged to a second inner surface of the second piston conductor at a second conducting interface, and a barrel affixed to the head-end interface at the second end, the barrel extending along the longitudinal axis having a sixth inner diameter greater than the third outer diameter of the arm, wherein a third inner surface of the barrel is slidably engaged to a third outer surface of the second piston conductor. 
     In another aspect of the presently disclosed subject matter, a work machine includes an electric engine and a conductor rod for providing electrical energy to the electric engine from a power source, the conductor rod extending a longitudinal axis from a first end proximate the work machine to a second end spaced laterally from the work machine. The conductor rod includes an arm section inserted into a barrel section. The arm section includes a first piston conductor affixed to a connector assembly at the second end, the first piston conductor extending along the longitudinal axis having a first inner diameter and a first outer diameter, a second piston conductor affixed to the connector assembly, the second piston conductor extending along the longitudinal axis having a second inner diameter greater than the first outer diameter and a second outer diameter, and an arm affixed to the connector assembly, the arm extending along the longitudinal axis having a third inner diameter greater than the second outer diameter and a third outer diameter. The barrel section includes a first cylinder conductor affixed to a head-end interface at the first end, the first cylinder conductor extending along the longitudinal axis having a fourth outer diameter and a fourth inner, wherein the fourth inner diameter is greater than the first outer diameter of the first piston conductor, wherein a first inner surface of the first cylinder conductor is slidably engaged to a first outer surface of the first piston conductor at a first conducting interface, a second cylinder conductor affixed to the head-end interface at the first end, the second cylinder conductor extending along the longitudinal axis having a fifth outer diameter less than the second inner diameter of the second piston conductor and greater than the fourth outer diameter of the first cylinder conductor, wherein a second outer surface of the second cylinder conductor is slidably engaged to a second inner surface of the second piston conductor at a second conducting interface, and a barrel affixed to the head-end interface, the barrel extending along the longitudinal axis having a sixth inner diameter greater than the third outer diameter of the arm, wherein a third inner surface of the barrel is slidably engaged to a third outer surface of the second piston conductor. 
     In a still further aspect of the presently disclosed subject matter, a method of assembling a conductor rod includes forming a barrel section by affixing a first cylinder conductor to a head-end interface using a first terminal connector, affixing a second cylinder conductor to the head-end interface using a second terminal connector, affixing a third cylinder conductor to the head-end interface using a third terminal connector, and affixing a barrel to the head-end interface using a fourth terminal connector. The method further includes forming an arm section by affixing a first piston conductor to a conductor assembly using a fifth terminal connector, affixing a second piston conductor to the conductor assembly using a sixth terminal connector, affixing a third piston conductor to the conductor assembly using a seventh terminal connector, affixing an arm to the conductor assembly using an eighth terminal connector, and inserting the arm section into the barrel section, whereby the first piston conductor is inserted into an interior space of the first cylinder conductor, the second piston conductor is inserted into a first cylinder cavity defined by an interior surface of the second cylinder conductor and an exterior surface of the first piston conductor, the third piston conductor is inserted into a second cylinder cavity defined by an interior surface of the third cylinder conductor and an exterior surface of second piston conductor, and the arm is inserted into a third cylinder cavity defined by an interior surface of the barrel and an exterior surface of the third piston conductor. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    illustrates an isometric view of a work machine within an XYZ coordinate system as one example suitable for carrying out the principles discussed in the present disclosure. 
         FIG.  2    illustrates a longitudinal cross-section of a conductor rod with an arm disposed in a barrel, in accordance with one or more examples of the present disclosure. 
         FIG.  3    is a longitudinal cross-sectional view of a conductor rod at a first end proximate to a head-end interface, in accordance with one or more examples of the present disclosure. 
         FIG.  4    is an isometric view of a cylinder conductor illustrating a ring-type terminal connector assembly, in accordance with one or more examples of the present disclosure. 
         FIG.  5    is a cross-sectional view showing the portion of a cylinder conductor affixed to connector assembly, in accordance with one or more examples of the present disclosure. 
         FIG.  6    is a cross-sectional view of a cylinder conductor and cuboid connectors along the cut lines illustrated in  FIG.  3   , in accordance with one or more examples of the present disclosure. 
         FIG.  7    illustrates a longitudinal section of a conductor rod in an extended position, in accordance with one or more examples of the present disclosure. 
         FIG.  8    illustrates a longitudinal section of conductor rod in a retracted position, in accordance with one or more examples of the present disclosure. 
         FIG.  9    is a longitudinal isometric view of a cross-section of a conductor rod showing conductor-to-conductor interfaces, in accordance with one or more examples of the present disclosure. 
         FIG.  10    illustrates a longitudinal section of a conductor rod that is rotatable, in accordance with one or more examples of the present disclosure. 
         FIG.  11    illustrates conductor a rod in a disengaged orientation, in accordance with one or more examples of the present disclosure. 
         FIG.  12    illustrates conductor a rod in an engaged orientation, in accordance with one or more examples of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Wherever possible, the same reference numbers will be used throughout the drawings to refer to same or like parts.  FIG.  1    illustrates an isometric view of a work machine  100  within an XYZ coordinate system as one example suitable for carrying out the principles discussed in the present disclosure. The exemplary work machine  100  travels parallel to the X axis along a roadway, also termed a haul route  101 , typically from a source to a destination within a worksite. In one implementation as illustrated, work machine  100  is a hauling machine that hauls a load within or from a worksite within a mining operation. For instance, the work machine  100  may haul excavated ore or other earthen materials from an excavation area along haul route  101  to dump sites and then return to the excavation area. In this arrangement, work machine  100  may be one of many similar machines configured to ferry earthen material in a trolley arrangement. While a large mining truck in this instance, work machine  100  may be any machine that carries a load between different locations within a worksite, examples of which include an articulated truck, an off-highway truck, an on-highway dump truck, a wheel tractor scraper, or any other similar machine. Alternatively, work machine  100  may be an off-highway truck, on-highway truck, a dump truck, an articulated truck, a loader, an excavator, a pipe layer, or a motor grader. In other implementations, work machine  100  need not haul a load and may be any machine associated with various industrial applications including, but not limited to, mining, agriculture, forestry, construction, and other industrial applications. 
     Referring to  FIG.  1   , an example work machine  100  includes a frame  103  powered by electric engine  102  to cause rotation of traction devices  104 . Traction devices  104  are typically four or more wheels with tires, although tracks or other mechanisms for engagement with the ground along haul route  101  are possible. Electric engine  102  functions to provide mechanical energy to work machine  100  based on an external electrical power source, such as described in further detail below. An example of mechanical energy provided by electric engine  102  includes propelling traction devices  104  to cause movement of work machine  100  along haul route  101 , but electric engine  102  also includes components sufficient to power other affiliated operations within work machine  100 . For instance, in some implementations, electric engine  102  includes equipment for converting electrical energy to provide pneumatic or hydraulic actions within work machine  100 . While electric engine  102  is configured to operate from an external electrical power source, electric engine  102  typically includes one or more batteries for storing electrical energy for auxiliary or backup operations. 
     In accordance with the principles of the present disclosure, and relevant to the presently disclosed subject matter, the work machine  100  further includes a conductor rod  106  configured to receive electrical power from a power rail  108 . In some examples, power rail  108  is one or more beams of metal arranged substantially parallel to and a distance above the ground. In  FIG.  1   , power rail  108  is positioned to be substantially parallel to the X axis and the direction of travel of work machine  100 . Support mechanisms hold power rail  108  in place along a distance at the side of haul route  101  for work machine  100  to traverse. The support mechanisms and power rail  108  may be modular in construction, enabling their disassembly and reassembly at different locations or their repositioning along the existing haul route  101 . In many examples, such as within a mining site, power rail  108  will not be configured continuously at a fixed distance along a side of haul route  101  and at a fixed height above the ground due, at least in part, to the variation of the terrain. Therefore, it is expected that the vertical, horizontal, and angular positions of the surface of power rail  108  in the XYZ planes will vary along haul route  101 . Moreover, while shown in  FIG.  1    to the left of work machine  100  as work machine  100  travels in the direction of the X axis, power rail  108  may be installed to the right of work machine  100  or in other locations suitable to the particular implementation. 
     Power rail  108  provides a source of electrical power for work machine  100  as either AC or DC. In some examples, power rail  108  has two or more conductors, each providing voltage and current at a different electrical pole. In one implementation (e.g., an implementation in which the power rail  108  includes three conductors), one conductor provides positive DC voltage, a second conductor provides negative DC voltage, and a third conductor provides 0 volts relative to the other two conductors. The two powered conductors within power rail  108  provide +1500 VDC and -1500 VDC. These values are exemplary, and other physical and electrical configurations for power rail  108  are available and within the knowledge of those of ordinary skill in the art Further, it should be understood that the voltages described herein are merely exemplary, as various levels of AC voltage may be used, as well as a combination of AC and DC voltages, depending on the particular configuration. 
     Conductor rod  106  enables electrical connection between work machine  100  and power rail  108 , including during movement of work machine  100  along haul route  101 . In the example shown in  FIG.  1   , conductor rod  106  is an elongated arm resembling a pole.  FIG.  1    shows conductor rod  106  positioned along a front side of work machine  100 , with respect to the direction of travel of work machine  100  in the direction of the X axis. In this arrangement, conductor rod  106  is located in  FIG.  1    in the Y-Z plane essentially along the Y axis with a first end  107  near a right side of work machine  100  and a second end  111  at a left side of work machine  100 . Conductor rod  106  may be attached to any convenient location within work machine  100 , such as to frame  103 , in a manner to couple conductor rod  106  to power rail  108 . Shown in  FIG.  1    as extending to a left side of work machine  100  toward power rail  108 , conductor rod  106  may alternatively be arranged to extend to a right side and at any desired angle from work machine  100  such that conductor rod  106  may be coupled to power rail  108  for obtaining electrical power. 
     As embodied in  FIG.  1   , conductor rod  106  includes a barrel  109  mounted to frame  103  of work machine  100 . Barrel  109  has a hollow interior and may be a conductive metal having suitable mechanical strength and resiliency, such as aluminum. Within barrel  109 , an arm  110  is retained. Arm  110  is slidably engaged within conductor rod  106  such that it may be extended or retracted axially, i.e., along the Y axis in  FIG.  1   , to adjust the reach of conductor rod  106 . Specifically, in a retracted position, arm  110  is caused to slide within barrel  109  of conductor rod  106  such that a length of conductor rod  106  roughly spans the width of work machine  100 . A junction  112  serves as the junction or interface between arm  110  and barrel  109 , which is the main body of conductor rod  106 . When arm  110  is fully retracted or collapsed into barrel  109 , junction  112  essentially becomes the left edge of conductor rod  106 . On the other hand, when arm  110  is extended from barrel  109  of conductor rod  106 , arm  110  may reach from work machine  100  to proximate power rail  108  on the side of haul route  101 . 
     Within, and possibly including barrel  109 , conductor rod  106  includes a series of electrical conductors passing longitudinally, at least from a head  122  at first end  107  of conductor rod  106  to a tip  124  of the conductor rod  106 . Typically, the conductors within conductor rod  106  are formed of a metallic material and are rigid. In some examples, the conductors are concentric tubes, or hollow cylinders, of solid metal such as copper, aluminum, gold, silver, nickel, zinc, or alloys thereof nested together and sized to provide electrical capacity sufficient for powering work machine  100 . Tubular conductors within arm  110  slidably engage with corresponding tubular conductors within barrel  109  to maintain electrical continuity as arm  110  is extended or retracted. In other examples, one or more concentric copper tubes, rather than aluminum, of varying diameters may be used as tubular conductors. Other types of conductive tubes may be used and are considered to be within the scope of the presently disclosed subject matter. 
     At the tip  124 , a connector assembly  114  provides an interface to power rail  108  via trailing arms  116  and contactor  118 . Power rail  108  is typically arranged along a side of haul route  101 , and work machine  100  is steered so that it traverses haul route  101  substantially in parallel with power rail  108 . Thus, in reference to  FIG.  1   , power rail  108  and a travel path for work machine  100  are substantially in parallel with each other and with the X axis. Contactor  118  is configured to maintain an electrical connection with power rail  108  while sliding along its surface in the direction of the X axis as work machine  100  moves. In some examples, trailing arms  116  are conductors coupled to contactor  118 , each conducting voltage and current at a different electrical pole and corresponding to the conductors within conductor rod  106 . In operation, electrical power is accessed from power rail  108  via contactor  118 , which remain in contact during movement of work machine  100 , and the electrical power is conducted through trailing arms  116  into connector assembly  114 . 
     From connector assembly  114 , the electrical power is conveyed at tip  124  through the nested tubular conductors within arm  110  and barrel  109  to head  122  of conductor rod  106  and through a head-end interface  120  to work machine  100 . Head-end interface  120  provides at least an electrical connection between conductor rod  106  and work machine  100  for powering electric engine  102  and otherwise enabling operations within work machine  100 . In some examples, head-end interface  120  may also provide an interface for inputs to control mechanical operation of conductor rod  106 , such as passageways for pressurized air of a pneumatic control system to extend and retract arm  110  or signaling for electronic controls. 
     As noted above, the tubular or cylindrical nature of conductor rod  106 , lending to a degree of rigidity, can provide a mechanism to conduct electrical power from a source to a load over an unsupported distance that may vary in length as the work machine  100  travels along a path. Further, as described above, trailing arms  116  are conductors coupled to contactor  118 , each conducting voltage and current at a different electrical pole and corresponding to the conductors within conductor rod  106 . Different cylindrical conductors within conductor rod  106  can provide for the transmission of different potentials along conductor rod  106 , illustrated in more detail in  FIG.  2   , below. 
       FIG.  2    illustrates a longitudinal cross-section of conductor rod  106  when arm  110  is retracted, or collapsed, into barrel  109 , in accordance with one or more examples of the present disclosure. More specifically,  FIG.  2    depicts a longitudinal section of conductor rod  106  between head-end interface  120  and connector assembly  114 , from head  122  to tip  124 , when viewed facing in the direction of travel for work machine  100 , i.e., in the direction of the X axis. Thus, conductor rod  106  lies in the Y-Z plane, as indicated in  FIG.  2   . 
     Referring to the right side of  FIG.  2   , barrel  109  contains an arrangement of concentric conductors of tubular shape, i.e., as hollow cylinders. In this example, from the axial center outward, first cylinder conductor  202  is positioned at a center of barrel  109  and is a tubular conductor made of aluminum or a similar metal with high electrical conductivity and high mechanical strength. For instance, an aluminum alloy such as 6061-T6 may be used for first cylinder conductor  202  and other conductive tubes in conductor rod  106 . Other suitable metals or alloys thereof may be used and are considered to be within the scope of the presently disclosed subject matter. In some examples, first cylinder conductor  202  has an outer diameter of approximately 3.5 inches to 4.5 inches. However, it should be understood that dimensions provided herein are merely for purposes of illustration and are not intended to be limitations, as dimensions described in relation to various components may be greater or less than the examples provided herein. First cylinder conductor  202  begins at head  122  and extends axially along conductor rod  106  around a longitudinal Y axis to a barrel end  205 . Barrel end  205  in this example of  FIG.  2    is approximately radial to junction  112 . As a tube, first cylinder conductor  202  defines first cylinder cavity  204  within its inner surface. If arm  110  were removed from barrel  109  in  FIG.  2   , first cylinder cavity  204  would be an open space within first cylinder conductor  202  traveling the length of conductor rod  106  from head  122  to barrel end  205 . In one example, first cylinder cavity  204  has a diameter of about 2.5 to 3 inches. 
     A second cylinder conductor  206  concentrically surrounds first cylinder conductor  202 . As with first cylinder conductor  202 , second cylinder conductor  206  is a tubular conductor made of aluminum or a similar metal with high electrical conductivity and high mechanical strength. Second cylinder conductor  206  is similarly positioned around a Y axis within  FIG.  2    and spans a distance from head  122  to barrel end  205 . In one example, second cylinder conductor  206  has an outer diameter of about 5 to 5.5 inches. These dimensions, as well as other dimensions discussed below, are merely examples and could be greater or lesser than the stated values. Being arranged concentrically around and, by definition, having a larger diameter than first cylinder conductor  202 , second cylinder conductor  206  forms a radial gap between it and first cylinder conductor  202 . In the example of  FIG.  2   , that gap is filled by second cylinder insulation  208 , which is a closed cell polyurethane foam. Other types of materials for second cylinder insulation  208  that provide electrical insulation and lightweight support within conductor rod  106  will be available and apparent to those of ordinary skill in the field. In some examples, second cylinder insulation  208  has a thickness of about 0.75 inches. 
     In some examples, second cylinder insulation  208  can be a dielectric. Dielectric materials can be solids, liquids, or gases. Some solids can be used as dielectrics, such as porcelain, glass, plastics, and the closed cell polyurethane foam described above. In configurations in which a cylinder conductor or piston conductor is hermetically sealed on both ends of the cylinder conductor or piston conductor, fluidic dielectrics can be used in gaps, such as radial gap first cylinder conductor  202  and second cylinder conductor  206 . Fluid dielectrics can include some forms of oil or gaseous dielectrics such as air, nitrogen, helium, and other dry gases such as sulfur hexafluoride. In further configurations in which a cylinder conductor or piston conductor is hermetically sealed on both ends of the cylinder conductor or piston conductor, a partial vacuum can be used. In various examples, a partial vacuum can be used as a nearly lossless dielectric even though its relative dielectric constant is unity. It should be noted that the dielectrics disclosed herein are merely examples, as other dielectrics may be used and are considered to be within the scope of the presently disclosed subject matter. Different dielectrics can be used in various radial gaps of conductor rod  106  to allow for different voltages and different types of potentials to be conducted by conductor rod  106 . 
     Moving farther out radially on the right side of  FIG.  2   , third cylinder conductor  210  concentrically surrounds second cylinder conductor  206  and first cylinder conductor  202 . Third cylinder conductor  210  is a tubular conductor made of aluminum or a similar metal with high electrical conductivity and high mechanical strength. As with the other tubes discussed, third cylinder conductor  210  extends from head  122  to barrel end  205  within conductor rod  106 . In one example, third cylinder conductor  210  has an outer diameter of about 8 to 9 inches. A third cylinder cavity  212  between second cylinder conductor  206  and third cylinder conductor  210  is an open space, which, if arm  110  were removed from barrel  109  in  FIG.  2   , would form a tubular cavity extending from head  122  to barrel end  205 . 
     Concentrically around third cylinder conductor  210  and the other tubular conductors, fourth cylinder conductor  214  forms an outer conductive path from head  122  to barrel end  205 . Similarly, fourth cylinder conductor  214  is a tubular conductor made of an aluminum alloy or a similar metal with high electrical conductivity and high mechanical strength. In one example, fourth cylinder conductor  214  has an outer diameter of about 14 inches. A gap between an outer diameter of third cylinder conductor  210  and an inner diameter of fourth cylinder conductor  214 , in some examples, is about 0.75 inches and is filled with fourth cylinder insulation  216 , which is a closed cell polyurethane foam, dielectric, or similar substance. 
     Radially beyond fourth cylinder conductor  214 , a covering or barrel shell  218  encases conductor rod  106 . Barrel shell  218  is typically a metal or similar substance providing structural integrity to conductor rod  106 . Barrel shell  218  has an inner diameter in excess of an outer diameter of fourth cylinder conductor  214 . As a result, a retraction cavity  220  of a tubular shape is formed between fourth cylinder conductor  214  and barrel shell  218  that extends from head  122  to barrel end  205 . A stop  222 , which is part of a housing for conductor rod  106  at junction  112 , defines a longitudinal end for retraction cavity  220  away from head  122 . Stop  222  generally aligns radially with barrel end  205  and junction  112 . 
     The various annular or tubular cavities within barrel  109 , namely, first cylinder cavity  204 , third cylinder cavity  212 , and the head end of retraction cavity  220  (barrel shell cavity  242 , described below), are sealed or capped by the attachment of head-end interface  120  to their ends at head  122 . The attachment of head-end interface  120  is designed to provide an airtight (or hermetic) seal within these cavities, for purposes to be understood further below. 
     Viewing  FIGS.  1  and  2    together, arm  110  is a substantially cylindrical body having a smaller outer diameter than an inner diameter of barrel shell  218  and that mates and slides into barrel  109 . As well as providing a longitudinal end for retraction cavity  220 , stop  222  also defines an inner diameter through which arm  110  slides, as shown to the left of  FIG.  2   . By sliding, it is meant that arm  110  may move longitudinally along the Y axis in connection with one or more surfaces within barrel  109  as arm  110  is moved axially with respect to conductor rod  106 , from left to right in  FIG.  2    for retraction and from right to left in  FIG.  2    for extension. The result of the sliding is the increase or decrease in the overall length of conductor rod  106  via arm  110 , as illustrated in  FIG.  1   . 
     Referring now to the left side of  FIG.  2   , arm  110  also contains a series of concentric conductors of cylindrical or tubular shape. In this example, from the axial center outward, first piston conductor  224  is positioned at a center of arm  110  and is, as with the other tubular conductors of arm  110 , made of a metal such as aluminum 6061-T6 or similar substance having high electrical conductivity and high mechanical strength. First piston conductor  224  extends from tip  124  to an arm end  225 , shown at the right side of  FIG.  2   . Being tubular, first piston conductor  224  has a first piston cavity  226  within its inner diameter that is filled with air or another gas. A second piston conductor  228  concentrically surrounds first piston conductor  224  and extends from tip  124  to arm end  225 . Second piston conductor  228  is made of a conductive material, and in some examples has an inner diameter of between about 5 and 6 inches. A space defined as second piston cavity  230  is formed between the inner diameter of second piston conductor  228  and the outer diameter of first piston conductor  224 , which is left unfilled other than with air or a similar gas. 
     Moving radially outward from second piston conductor  228 , a third piston conductor  232  axially centered on the Y axis concentrically surrounds second piston conductor  228 . Similarly made of a conductive material, third piston conductor  232  is set off radially from second piston conductor  228  a distance of less than 1 inch, which is filled with a third piston insulation  234 . As with second cylinder insulation  208  and fourth cylinder insulation  216 , third piston insulation  234  can be a closed cell polyurethane foam or comparable substance providing electrical insulation and lightweight stability. Finally, an arm shell  236  of conductive material such as metal concentrically surrounds third piston conductor  232  from tip  124  to about arm end  225 . In some examples, arm shell  236  has an outer diameter of about 11.625 inches. Within an inner diameter of arm shell  236 , an arm shell cavity  238  of free space exists between arm shell  236  and third piston conductor  232 . 
     In some examples, the outer surface of arm shell  236  includes gasket  240 , which serves to stably set apart arm shell  236 , and arm  110  generally, from barrel shell  218 . As illustrated in  FIG.  2   , as arm  110  is retracted or extended within barrel  109 , gasket  240  separates retraction cavity  220  from a barrel shell cavity  242 . As well, gasket  240  can help retain arm  110  within conductor rod  106  in a state of maximum extension by butting against stop  222 . Additionally, in a manner discussed below, a radial wall of gasket  240  provides leverage for pneumatic pressure applied within retraction cavity  220  to cause arm  110  to be retracted. 
     As illustrated,  FIG.  2    represents an arrangement in which conductor rod  106  essentially has two longitudinal halves. A first half, barrel  109 , on the right side of  FIG.  2   , includes barrel shell  218  enclosing a series of tubular cylinder conductors aligned along the Y axis. Those cylinder conductors, viewed radially from the center axis, are first cylinder conductor  202 , second cylinder conductor  206 , third cylinder conductor  210 , and fourth cylinder conductor  214 . Within that concentric arrangement, tubular regions of open space exist within first cylinder cavity  204  and third cylinder cavity  212 . Further, barrel shell  218  encases barrel  109  and forms an open space within retraction cavity  220  and barrel shell cavity  242 . On the left side of  FIG.  2   , arm  110  includes arm shell  236  enclosing a series of tubular piston conductors also aligned along the longitudinal axis of conductor rod  106 . Those piston conductors, viewed radially from the center axis, are first piston conductor  224 , second piston conductor  228 , and third piston conductor  232 . Within that concentric arrangement, tubular regions of open space exist within first piston cavity  226  and second piston cavity  230 . Further arm shell  236  encases arm  110  and forms an open space within arm shell cavity  238 . 
     In an operating state for conductor rod  106 , arm  110  is inserted into barrel  109  to form a nested configuration of the piston conductors and the cylinder conductors. The radial sequence of tubular conductors within barrel  109  are the inverse of, and complementary to, the radial sequence of tubular conductors within arm  110 . For example, when arm  110  is inserted into barrel  109 , the outer diameter of first piston conductor  224  fits within the inner diameter of first cylinder conductor  202 , and the empty space within first cylinder cavity  204  enables first piston conductor  224  to slide forward into barrel  109 . During and after the sliding, first piston conductor  224  maintains electrical contact with first cylinder conductor  202 , permitting electrical conductivity between those tubular conductors. When first piston conductor  224  is mated within first cylinder conductor  202 , first piston cavity  226  and first cylinder cavity  204  extend axially through conductor rod  106  at least from head  122  to tip  124 . 
     Similarly, when the combination of second piston conductor  228 , third piston conductor  232 , and interposed third piston insulation  234  are slid as part of arm  110  into barrel  109 , the outer diameter of third piston conductor  232  fits within the inner diameter of third cylinder conductor  210 , and the inner diameter of second piston conductor  228  is slidably engaged with and is inserted over the outer diameter of second cylinder conductor  206 . As a result, the sandwich of second piston conductor  228 , third piston conductor  232 , and third piston insulation  234  slide into the empty space defined by third cylinder cavity  212 . In doing so, third piston conductor  232  slides against and electrically contacts third cylinder conductor  210 , and second piston conductor  228  slides against and electrically contacts second cylinder conductor  206 . In some examples, and as shown similarly in  FIG.  2   , when conductor rod  106  is fully collapsed, at least some volume of empty space will remain within third cylinder cavity  212 , which will have an annular or tubular shape and be defined radially by portions of second cylinder conductor  206  and third cylinder conductor  210 . 
     Conversely, when arm  110  is inserted into barrel  109 , the cylinder conductors will slide into cavities within the piston from left to right in  FIG.  2   , and the cylinder conductors will become nested with the piston conductors. For example, the combination of first cylinder conductor  202 , second cylinder conductor  206 , and second cylinder insulation  208  will slide into the open space defined by second piston cavity  230  within arm  110 , during which, as mentioned, first cylinder conductor  202  electrically contacts first piston conductor  224  and second cylinder conductor  206  electrically contacts second piston conductor  228 . Likewise, in the illustrated example, the sandwich of third cylinder conductor  210 , fourth cylinder conductor  214 , and fourth cylinder insulation  216  will slide into the open space defined by arm shell cavity  238  within arm  110 . Third cylinder conductor  210  will then slidingly contact third piston conductor  232 , and fourth cylinder conductor  214  will do the same against arm shell  236 . 
     As mentioned above, head-end interface  120  provides at least an electrical connection between conductor rod  106  and work machine  100  for powering electric engine  102  and otherwise enabling operations within work machine  100 . Head-end interface  120  also provides the physical securement of first cylinder conductor  202 , second cylinder conductor  206 , third cylinder conductor  210 , and fourth cylinder conductor  214  to work machine  100 , allowing arm  110  to extend and retract in relation to conductor rod  106 , illustrated in more detail in  FIGS.  3  and  4   , below. 
       FIG.  3    is a longitudinal cross-sectional view of a conductor rod  300  at a first end  307  proximate to head-end interface  310 , in accordance with one or more examples of the present disclosure Conductor rod  300  is constructed in a manner similar to conductor rod  106  of  FIGS.  1  and  2   . However, conductor rod  300  is illustrated as having piston conductors removed for purposes of description.  FIG.  3    depicts a longitudinal cross-sectional of a portion of conductor rod  300  when viewed facing in the direction of travel for a work machine, such as work machine  100  of  FIG.  1   , i.e., in the direction of the X axis. Thus, conductor rod  300  lies in the Y-Z plane, as indicated in  FIG.  3   . Conductor rod  300  includes first cylinder conductor  302 , second cylinder conductor  304 , third cylinder conductor  306 , and barrel  308 . Conductor rod  300  includes connector assembly  312 . In a manner similar to the conductor rod  106  of  FIG.  1   , connector assembly  312  is located proximate to a power supply to conduct power from the power supply to work machine  100  (or load). 
     First cylinder conductor  302 , second cylinder conductor  304 , and third cylinder conductor  306  are concentric conductors of tubular shape, i.e. as hollow cylinders. In  FIG.  3   , from the axial center outward, first cylinder conductor  302  is positioned at a center of barrel  308 . Second cylinder conductor  304  concentrically surrounds first cylinder conductor  302 . As with first cylinder conductor  302 , second cylinder conductor  304  is a tubular conductor made of aluminum or a similar metal with high electrical conductivity and high mechanical strength. Second cylinder conductor  304  is similarly positioned around a Y axis within  FIG.  3   . Moving farther out radially, third cylinder conductor  306  concentrically surrounds second cylinder conductor  304  and first cylinder conductor  302 . Concentrically around third cylinder conductor  306  and the other tubular conductors, barrel  308  forms an outer conductive path. In some examples, barrel  308  can act as a fourth cylinder conductor if constructed from a conductive material. First cylinder conductor  302 , second cylinder conductor  304 , third cylinder conductor  306 , and barrel  308  span a distance from head-end interface  310  to connector assembly  312 . Radially beyond fourth cylinder conductor  214 , barrel  308  encases conductor rod  300 . Barrel  308  is typically a metal or similar substance providing structural integrity to conductor rod  300 . However, in some examples, barrel  308  is a non-conductive material that isolations the electrically energized interior of conductor rod  300  from an environment. Barrel  308  has an inner diameter in excess of an outer diameter of third cylinder conductor  306 . 
     As tubes, first cylinder conductor  302  defines first cylinder cavity  314  within its inner surface, second cylinder conductor  304  defines second cylinder cavity  316  between its inner surface and the outer surface of the first cylinder conductor  302 , third cylinder conductor  306  defines third cylinder cavity  318  between its inner surface and the outer surface of the second cylinder conductor  304 , barrel  308  defines fourth cylinder cavity  320  between its inner surface and the outer surface of the third cylinder conductor  306 . First cylinder cavity  314 , second cylinder cavity  316 , third cylinder cavity  318 , and/or fourth cylinder cavity  320  can be filled with insulative materials such as closed cell polyurethane foam. In other examples, first cylinder cavity  314 , second cylinder cavity  316 , third cylinder cavity  318 , and/or fourth cylinder cavity  320  are filled with a dielectric. Dielectric materials can be solids, liquids, or gases. Some solids can be used as dielectrics, such as porcelain, glass, plastics, and the closed cell polyurethane foam described above. In configurations in which a cylinder conductor is hermetically sealed on both ends of conductor rod  300 , fluidic dielectrics can be used in cavities, First cylinder cavity  314 , second cylinder cavity  316 , third cylinder cavity 0.318, and/or fourth cylinder cavity  320 . Fluid dielectrics can include some forms of oil or gaseous dielectrics such as air, nitrogen, helium, and other dry gases such as sulfur hexafluoride. In further configurations in which a cylinder conductor or piston conductor is hermetically sealed on both ends of the cylinder conductor or piston conductor, a partial vacuum can be used. In various examples, a partial vacuum can be used as a nearly lossless dielectric even though its relative dielectric constant is unity. It should be noted that the dielectrics disclosed herein are merely examples, as other dielectrics may be used and are considered to be within the scope of the presently disclosed subject matter. 
     Different dielectrics can be used in various cylinder cavities of conductor rod  300  to allow for different voltages and different types of potentials to be conducted by conductor rod  300 . For example, first cylinder conductor  302  and second cylinder conductor  304  can be configured to conduct a DC voltage and third cylinder conductor  306  can be configured to conduct an AC voltage. Because both first cylinder conductor  302  and second cylinder conductor  304  are conducting DC voltage, there may be no need or requirement to have a dielectric other than air between first cylinder conductor  302  and second cylinder conductor  304 . However, if the AC voltage being carried on third cylinder conductor  306  is of a certain voltage level or frequency, a dielectric of suitable strength can be used to prevent a short between second cylinder conductor  304  and third cylinder conductor  306 . 
     The various annular or tubular cavities within barrel  308 , namely, first cylinder cavity  314 , second cylinder cavity  316 , third cylinder cavity 0.318, and/or fourth cylinder cavity  320 , are sealed or capped by the attachment of the ends of the cylinder conductors to an interface. In  FIG.  3   , the interface is connector assembly  312 , though the same technology and techniques can be used to attach the other ends of cylinder conductors to another interfaces, such as head-end interface  120  of  FIG.  2   . The attachment is designed to provide an airtight (or hermetic) seal within these cavities. For example, when using fluidic insulative materials or dielectrics, or a partial vacuum, a hermetic seal maintains the fluid within the particular cavity to which the fluid is inserted, or, maintains the partial vacuum from which the air was pumped out. To provide for an airtight seal, the ends of the cylinder conductors can be affixed to interfaces using various technologies, including welding, glue, adhesive, gaskets, and the like. To removably affix the ends of the cylinder conductors, whereby the ends can be installed, removed, and reinstalled, the cylinder conductors can use a terminal connector assembly. The terminal connector assemblies use a threaded member inserted into a terminal receiver. The terminal receiver is affixed to a respective cylinder conductor, thereby providing for affixing and removing the cylinder conductors from either a head-end interface, such as head-end interface of  FIGS.  1  and  2   , or connector assembly  312 . 
     Conductor rod  300  of  FIG.  3    is illustrated as using different types of terminal connector assemblies. In  FIG.  3   , first cylinder conductor  302  is affixed to connector assembly  312  using terminal connector assembly  330  and threaded members  332 A and  332 B. Threaded members  332 A and  332 B are inserted through connector assembly  312  and into terminal connector assembly  330 . At head-end interface  310 , first cylinder conductor  302  is affixed to head-end interface  310  using terminal connector assembly  334  and threaded members  336 A and  336 B. Threaded members  336 A and  336 B are inserted through head-end interface  310  and into terminal connector assembly  334 . Terminal connector assemblies  330  and  334  are affixed to first cylinder conductor  302  using various technologies such as, but not limited to, welding, soldering, and the like. 
     Terminal connector assemblies  330  and  334  are ring-type connector assemblies, explained in more detail in  FIGS.  4  and  5   , below. However, some examples of the presently disclosed subject matter us cuboid-type terminal connector assemblies rather than using ring. Ssecond cylinder conductor  304 , third cylinder conductor  306 , and barrel  308  are affixed to connector assembly  312  using cuboid connectors. More specifically, second cylinder conductor  304  is affixed to connector assembly  312  using cuboid connectors  360 A and  360 B. Third cylinder conductor  306  is affixed to connector assembly  312  using cuboid connectors  362 A and  362 B. Barrel  308  is affixed to connector assembly  312  using cuboid connectors  364 A and  364 B. As with terminal connector assembly  330 , the cuboid connectors use threaded members to affix their respective cuboid connectors to connector assembly  312 , and thus, affixing their respective cylinder conductor to connector assembly  312 . Threaded members  346 A and  346 B securely affix cuboid connectors  360 A and  360 B, respectively, to connector assembly  312 . Threaded members  348 A and  348 B securely affix cuboid connectors  362 A and  362 B, respectively, to connector assembly  312 . Threaded members  350 A and  350 B securely affix cuboid connectors  364 A and  364 B, respectively, to connector assembly  312 . Further details of an example ring-type terminal connector assembly are provided in  FIGS.  4  and  5   , below, and further details of an example cuboid-type terminal connector assembly are provided in  FIG.  6   , below. 
       FIG.  4    is an isometric view of first cylinder conductor  302  illustrating ring-type terminal connector assembly  330 , in accordance with one or more examples of the present disclosure. Ring-type terminal connector assemblies use a cylindrical ring to which a cylinder conductor is affixed. First cylinder conductor  302  has disposed within an inner diameter of first cylinder conductor  302  a terminal connector assembly  330 . Terminal connector assembly  330  is a tubular shape that has an outer diameter, when measured radially from the center of first cylinder conductor  302 , that allows an inner surface of first cylinder conductor  302  to abut and be affixed to terminal connector assembly  330  at interface  400 . Terminal connector assembly  330  includes receiving locations  402  and  404 . Receiving locations  402  and  404  are locations in terminal connector assembly  330  into which threaded members  332 A and  332 B are inserted and threaded to secure first cylinder conductor  302  and terminal connector assembly  330  to connector assembly  312 . It should be noted that because terminal connector assembly  330  is tubular in shape, first cylinder conductor  302  may be removably affixed against connector assembly  312  without mechanical affixment to terminal connector assembly  330 . For example, terminal connector assembly  330  may be removably affixed to connector assembly  312  and then first cylinder conductor  302  is inserted onto and around terminal connector assembly  330 , whereby an inner surface  406  of first cylinder conductor  302  is inserted over an outer surface  408  of terminal connector assembly  330  at interface  400 . While this may not mechanically affix first cylinder conductor  302  to connector assembly  312  in the same manner as if first cylinder conductor  302  was welded to terminal connector assembly  330 , when first cylinder conductor  302  is placed over terminal connector assembly  330 , terminal connector assembly  330  positionally secures first cylinder conductor  302 . First cylinder conductor  302  may be affixed to a particular location on connector assembly  312  using not only the secured position of terminal connector assembly  330  on connector assembly  312 , but also by the use of shaped surfaces, illustrated in more detail in  FIG.  5   , below. 
       FIG.  5    is a cross-sectional view showing the portion of first cylinder conductor  302  affixed to connector assembly  312 , in accordance with one or more examples of the present disclosure. As illustrated in  FIG.  5   , first cylinder conductor  302  is affixed to connector assembly  312  by terminal connector assembly  330 . In  FIG.  5   , first cylinder conductor  302  is engaged onto terminal connector assembly  330  at interface  400 . As noted above, first cylinder conductor  302  can be engaged onto terminal connector assembly  330  at interface  400  by affixing first cylinder conductor  302  to terminal connector assembly  330  using welding, soldering, or other similar technique. In another example, first cylinder conductor  302  can be engaged onto terminal connector assembly  330  at interface  400  by slidable engaging first cylinder conductor  302  onto terminal connector assembly  330  at interface  400 . The presently disclosed subject matter is not limited to any particular technology for affixing, either permanently or temporarily, first cylinder conductor  302  onto terminal connector assembly  330 . Also illustrated in  FIG.  5    are threaded members  332 A and  332 B. Threaded members  332 A and  332 B are inserted through connector assembly  312  thru receiving locations  402  and  404 , respectively, and into terminal connector assembly  330 . 
     As noted above in  FIG.  4   , first cylinder conductor  302  and terminal connector assembly  330  may be shaped or formed to provide additional securement capabilities. This means that and end of first cylinder conductor  302  and terminal connector assembly  330  may not be perfectly cylindrical, but rather, may be shaped in a manner to provide additional mechanical benefits. In  FIG.  5   , first cylinder conductor  302  includes flange  500  and receiving slot  502 . Terminal connector assembly  330  includes flange  504 . In some examples, the flange  504  is sized and shaped to fit securely within receiving slot  502 . Flange  500  can be sized and shaped to provide an increased surface area onto which first cylinder conductor  302  is secured to the surface of connector assembly  312 . In a similar manner, flange  504  can be sized and shaped to provide an increased surface area onto which terminal connector assembly  330  is secured to the surface of connector assembly  312 . The additional surface area provided by flange  500  and flange  504  can provide for hermetically sealing first cylinder conductor  302  to connector assembly  312 . 
       FIGS.  4  and  5    illustrate one technology for securing a cylinder conductor to connector assembly  312  or head-end interface  310 . Terminal connector assembly  330  uses a ring structure over which and onto first cylinder conductor  302  is inserted. However, other technologies may be used. The cylinder conductors can be permanently affixed to their respective cuboid connectors using welding, soldering, or other similar technology. In other examples, the cylinder conductors can be placed against their respective cuboid connectors whereby the cuboid connector provides a physical barrier to movement of the cylinder conductor. In either technology, the cuboid connector is sized and shaped to abut to an outer surface of their respective cylinder conductor, illustrated in more detail in  FIG.  6   . 
       FIG.  6    is a cross-sectional view of second cylinder conductor  304  and cuboid connectors  360 A and  360 B along the cut lines illustrated in  FIG.  3    but with first cylinder conductor  302  and terminal connector assembly  330  removed for purposes of simplicity, in accordance with one or more examples of the present disclosure. As shown in  FIG.  6   , cuboid connectors  360 A and  360 B abut to an outer surface of second cylinder conductor  304  at interfaces  600 A and  600 B. As noted above, second cylinder conductor  304  can be engaged with cuboid connectors  360 A and  360 B at interfaces  600 A and  600 B by affixing second cylinder conductor  304  to cuboid connectors  360 A and  360 B at interfaces  600 A and  600 B, respectively, using welding, soldering, or other similar techniques. In another example, second cylinder conductor  304  can be engaged into cuboid connectors  360 A and  360 B at interfaces  600 A and  600 B by slidably engaging second cylinder conductor  304  into the inner surfaces of cuboid connectors  360 A and  360 B at interfaces  600 A and  600 B. The presently disclosed subject matter is not limited to any particular technology for affixing, either permanently or temporarily, second cylinder conductor  304  onto cuboid connectors  360 A and  360 B. Also illustrated in  FIG.  6    are receiving locations  602  and  604 , into which threaded members  346 A and  346 B are inserted. 
     As described above, a conductor rod according to various examples described herein can extend and retract to accommodate a moving or changing distance between a load and a source of electrical power. In the example illustrated in  FIG.  1   , as work machine  100  travels along a path, the distance between work machine  100  and power rail  108  may change. When arm  110  is fully retracted or collapsed into barrel  109 , junction  112  essentially becomes the left edge of conductor rod  106 . On the other hand, when arm  110  is extended from barrel  109  of conductor rod  106 , arm  110  may reach from work machine  100  to proximate power rail  108  on the side of haul route  101 .  FIGS.  7  and  8    are illustrations showing the sliding, or extending/retracting, nature of a conductor rod. 
       FIGS.  7  and  8    illustrates a longitudinal section of a conductor rod  700  in an extended and retracted position, with  FIG.  7    showing an extended position and  FIG.  8    showing a retracted position, in accordance with one or more examples of the present disclosure. For the purposes of simplification, one cylinder conductor (e.g., cylinder conductor  702 ), and one piston conductor (e.g., piston conductor  704 ) are illustrated. Also illustrated are barrel  706  and arm  708 . In  FIG.  7   , head-end interface  710  is mechanically and electrically affixed to a load  711 , such as work machine  100  of  FIG.  1   . Barrel  706  is affixed to head-end interface  710  and arm  708  is affixed to connector assembly  712 . Connector assembly  712  is connected to a power source  713 . Power source  713  provides electrical power through connector assembly  712 , piston conductor  704 , cylinder conductor  702 , and through head-end interface  710  to load  711 . As illustrated in  FIG.  7   , a surface  714  of head-end interface  710  interior to conductor rod  700  is separated from a surface  716  of connector assembly  412  interior to conductor rod  700  by a distance defined by line AB. In  FIG.  8   , conductor rod  700  has been retracted from the length illustrated by line AB to the length illustrated by line CD. Line AB of  FIG.  7    is shown in  FIG.  8    for the purposes of comparison. In  FIG.  8   , in the retracted position, a distal end  720  of arm  708  and a distal end  722  of piston conductor  704  nearly abuts surface  714  of head-end interface  710 , whereas in  FIG.  7   , distal end  720  of arm  708  and distal end  722  of piston conductor  704  in  FIG.  8    a greater distance from surface  714  of head-end interface  710 . This is illustrated by showing the distance defined by line AB being greater than the distance defined by line CD. 
     As a conductor rod, such as the conductor rod  700  of  FIGS.  7  and  8   , extends and retracts, the physical and electrical interface between a cylinder conductor and its respective piston conductor is maintained. This is done to maintain electrical continuity between a load and a power source regardless of the extended or retracted length of conductor rod  700 . Examples of physical and electrical interfaces that may be used are illustrated in more detail in  FIG.  9   , below. 
       FIG.  9    illustrates a longitudinal isometric view of a cross-section of a conductor rod  900  showing conductor-to-conductor interfaces, in accordance with one or more examples of the present disclosure. Conductor rod  900  is constructed in a manner to conductor rod  106  of  FIGS.  1  and  2   . Conductor rod  900  includes first cylinder conductor  902 , second cylinder conductor  904 , third cylinder conductor  906 , and barrel  908 . First cylinder conductor  902 , second cylinder conductor  904 , third cylinder conductor  906 , and barrel  908  are mechanically affixed to head-end interface  910 . Conductor rod  900  further includes first piston conductor  912 , second piston conductor  914 , third piston conductor  916 , and arm  918 . First cylinder conductor  902  concentrically surrounds first piston conductor  912  from radius HI along axial length FG. Second piston conductor  914  concentrically surrounds second cylinder conductor  904  from radius HI along axial length FG. Third cylinder conductor  906  concentrically surrounds third piston conductor  916  from radius HI along axial length FG. Barrel  908  concentrically surrounds arm  918  from radius HI along axial length FG. First piston conductor  912 , second piston conductor  914 , third piston conductor  916 , and arm  918  are insertable into and retractable from first cylinder conductor  902 , second cylinder conductor  904 , third cylinder conductor  906 , and barrel  908  in a manner similar to the conductor rod  700  of  FIGS.  7  and  8   . First cylinder conductor  902  is mechanically affixed to head-end interface  910  by various terminal connectors, such as terminal connector  920 , by way of example. Second cylinder conductor  904  is mechanically affixed to head-end interface  910  by various terminal connectors, such as terminal connector  922 , by way of example. Third cylinder conductor  906  is mechanically affixed to head-end interface  910  by various terminal connectors, such as terminal connector  924 , by way of example. Barrel  908  is mechanically affixed to head-end interface  910  by various terminal connectors, such as terminal connector  926 , by way of example. 
     Piston conductors 912-916 and arm  918  are in electrical and physical communication with their respective cylinder conductors 902-906 and barrel  908  via one or more conducting interfaces. For example, a conducting interface  928  comprises a contacting interface between an exterior contacting surface  929  of arm  918  and an interior contacting surface  931  of barrel  908 . Conducting interface  928  provides both a slidable physical interface as well as an electrical interface between barrel  908  and arm  918 . Acting as an electrical interface, electrical power is transferred from piston conductors 912-916 to their respective cylinder conductors 902-906, allowing for the continuous transfer of electrical power while the conductor rod  900  extends and retracts. Various technologies may be used to provide for a physical and electrical interface. The arm  918  extends and retracts by sliding along the conducting interface  928 , maintaining a physical and electrical interface. 
     Another example of a conducting interface is conducting interface  930 . Rather than direct contact between a cylinder conductor and a piston conductor acting as an electrical and physical interface, conducting interface  930  uses carbon brushes, such as brush  932 . Brush  932  is a brush formed from a conductive material, such as carbon or graphite, that provides both a physical and electrical interface between second cylinder conductor  904  and second piston conductor  914 . Brush  932  may be formed by compacting a mix of materials such as carbon, graphite, and metallic power (e.g. copper) into a solid piece of material sized and shaped to be used in conducting interface  930 . 
     Another example of an electrical interface material that provides for the conduction of electrical power from a piston conductor to a cylinder conductor is a metallic alloy that is liquid at a certain temperature, such as room temperature. An example of a metallic alloys is GALINSTAN. GALINSTAN is a eutectic alloy composed of gallium, indium, and tin which melts at -19 C (-2 F) and is thus liquid at room temperature. It should be noted, however, that other metal allows with properties similar to GALINSTAN may be used and are considered to be within the scope of the presently disclosed subject matter. 
     In order to keep a metallic alloy at an interface, the metallic alloy will be contained within a space enclosed by the surfaces of the piston conductor and the cylinder conductor in which the liquid alloy is being used. For example, conducting interface  934  is a space defined by an interior surface  939  of first cylinder conductor  902  and an exterior surface  941  of first piston conductor  912 . Conducting interface  934  is configured to act as a fluidic barrier, reducing or eliminating potential leaks of the liquid metallic alloy contained therein into other areas of the conductor rod  900 . As first piston conductor  912  extends and retracts within first cylinder conductor  902 , conducting interface  934  with a liquid metallic alloy contained therein provide for a constant electrical connection between first cylinder conductor  902  and first piston conductor  912 . 
     During use, the conducting interface  934  may be filled with additional liquid metallic alloy.  FIG.  9    illustrates one manner in which this may be accomplished, though other technologies for filling or refilling conducting interface  934  with additional liquid metallic alloy may be used and are considered to be within the scope of the presently disclosed subject matter. In  FIG.  9   , to introduce a liquid metallic alloy into conducting interface  934 , piston channel  936 , and interface channel  938  are used. To introduce a liquid metallic alloy into conducting interface  934 , conductor rod  900  is retracted so that first piston conductor  912  abuts or nearly abuts interface channel  938  so that interface channel  938  is in liquid communication with piston channel  936 . Terminal connector  920  is removed, providing for interface channel  938  to extend from an outer surface of head-end interface  910  to piston channel  936 . The liquid metallic alloy can be introduced at input  940 , through interface channel  938 , through piston channel  936 , and into conducting interface  934 . 
     An example process to assemble or manufacture conductor rod  900  of  FIG.  9    commences with assembling a barrel section  960 . Barrel section  960  includes a barrel and any other cylinder conductor affixed to a head-end interface. Conductor rod  900  further includes an arm section  962 . Arm section  962  includes an arm and any other piston conductor affixed to a terminal connector. As described above, an arm section  962  is designed to slide into and out of a barrel section  960 . Barrel section  960  is formed by affixing first cylinder conductor  902 , second cylinder conductor  904 , third cylinder conductor  906 , and barrel  908  to head-end interface  910  using the terminal connectors. As described above, first cylinder conductor  902  is mechanically affixed to head-end interface  910  by various terminal connectors, such as terminal connector  920 , by way of example. Second cylinder conductor  904  is mechanically affixed to head-end interface  910  by various terminal connectors, such as terminal connector  922 , by way of example. Third cylinder conductor  906  is mechanically affixed to head-end interface  910  by various terminal connectors, such as terminal connector  924 , by way of example. Barrel  908  is mechanically affixed to head-end interface  910  by various terminal connectors, such as terminal connector  926 , by way of example. Once first cylinder conductor  902 , second cylinder conductor  904 , third cylinder conductor  906 , and barrel  908  are affixed to head-end interface  910 , the assembly of the barrel end is complete. To assemble arm section  962 , first piston conductor  912 , second piston conductor  914 , third piston conductor  916 , and arm  918  are affixed to a conductor assembly, such as connector assembly  114  of  FIG.  1   . Once first piston conductor  912 , second piston conductor  914 , third piston conductor  916 , and arm  918  are affixed to a conductor assembly, the arm end assembly is complete. Arm section  962  is thereafter inserted into barrel section  960 , whereby first piston conductor  912  is inserted into first cylinder conductor  902 , second piston conductor  914  is inserted over an outer surface  952  of second cylinder conductor  904 , third piston conductor  916  is inserted into an interior surface  954  of third cylinder conductor, and arm  918  is inserted into an interior surface  956  of barrel  908 . In some examples, the assembly process continues by affixing the barrel  109  to the work machine  100 . In an operating state for conductor rod  900 , arm section  962  is inserted into barrel section  960  to form a nested configuration of the piston conductors and the cylinder conductors. The radial sequence of tubular conductors within barrel section  960  are the inverse of, and complementary to, the radial sequence of piston or tubular conductors within arm section  962 . For example, when arm section  962  is inserted into barrel section  960 , the outer diameter of first piston conductor  912  fits within the inner diameter of first cylinder conductor  902 , second piston conductor  914  fits onto an outer diameter of second cylinder conductor  904 , and an inner diameter of third piston conductor  916  fits within an inner diameter of third cylinder conductor  906 . 
     As noted above, various configurations of a conductor rod, such as the conductor rod  900  of  FIG.  9   , provide for the extension and retraction of the conductor rod  900  to suit dynamic distance changes between a load, such as work machine  100  of  FIG.  1   , and a source of power, such as power rail  108  of  FIG.  1   . As the load moves transversely in relation to the power source, there may be lengths of the conductor rod that are not suitable for maintaining an electrical and physical connection between the load and the power source. For example, if work machine  100  of  FIG.  1    moves too close to power rail  108 , it may be desirable to have conductor rod  106  disengage trailing arms  116  and contactor  118  from power rail  108  to, among other reasons, prevent damage to either work machine  100  or power rail  108 . In another example, if work machine  100  moves too far away from power rail  108 , it may be desirable to have conductor rod  106  disengage trailing arms  116  and contactor  118  from power rail  108 . Thus, in some examples, it may be desirable to use a retaining pin and retaining groove to cause a rotational motion of a conductor rod, whereby when rotated, the conductor rod is disengaged from a power rail, illustrated in more detail in  FIGS.  10 - 12   , below. 
       FIG.  10    illustrates a longitudinal section of a conductor rod  1000  that is rotatable, in accordance with various examples described herein. Conductor rod  1000  is shown without a barrel, such as barrel  109  of  FIG.  1   , or arm, such as arm  110  of  FIG.  1   , solely for purposes of illustration and not by way of limitation. Conductor rod  1000  includes head-end interface  1002  used to mechanically and electrically connect conductor rod  1000  to a load, such as work machine  100  of  FIG.  1   . Conductor rod  1000  further includes connector assembly  1004 . Connector assembly  1004  provides an interface to a power rail, such as power rail  108  of  FIG.  1   , though trailing arms and a contactor, such as trailing arms  116  and contactor  118  of  FIG.  1   . Connector assembly  1004  includes power connectors, such as power connector  1006 , that electrically and physical connect connector assembly  1004  to trailing arms  116 . 
     Conductor rod  1000  has cylinder conductor  1008  mechanically connected to head-end interface  1002  and junction  1012 . Piston conductor  1010  is mechanically connected to connector assembly  1004  through junction  1012 . Cylinder conductor  1008  and piston conductor  1010  are cylindrical in nature, each having an inner diameter and outer diameter, the sizes of which depend on the particular configuration. As noted above, conductor rod  1000  is shown without a barrel or arm, which would enclose cylinder conductor  1008  and piston conductor  1010 . Piston conductor  1010  is slidable within junction  1012  and an interior space of cylinder conductor  1008  in a manner similar to the piston conductor/cylinder conductor arrangements described hereinabove. 
     To provide for a rotation of connector assembly  1004  about central axis RT extending longitudinally through the center of conductor rod  1000  based on the position of piston conductor  1010  within cylinder conductor  1008 , cylinder conductor  1008  includes retaining groove  1014 . Retaining groove  1014  is a channel formed through surface  1015  of cylinder conductor  1008 . The retaining groove  1014  extends a length of cylinder conductor  1008 . Piston conductor  1010  includes retaining pin  1016  mechanically affixed to an outer surface  1027  of piston conductor  1010  and sized to fit and be slidable within retaining groove  1014 , illustrated in more detail in inset  1018 . Inset  1018  is a close-up, cross-sectional illustration viewed from head-end interface  1002  towards junction  1012 . Shown in inset  1018  is piston conductor  1010  and retaining pin  1016 . Retaining pin  1016  is mechanically affixed to outer surface  1027  of piston conductor  1010 . Retaining pin  1016  is disposed within retaining groove  1014  formed within cylinder conductor  1008 . As piston conductor  1010  extends and retracts within cylinder conductor  1008 , retaining pin  1016  slides within retaining groove  1014 . 
     Returning to  FIG.  10   , retaining groove  1014  includes disengaging sections  1022  and  1024  and engaged section  1026 . Engaged section  1026  is illustrated as being the area of retaining groove  1014  between length EF, whereas disengaging sections  1022  and  1024  are illustrated as being the areas outside of length EF. Disengaging sections  1022  and  1024  are defined by curves that modify the retaining groove  1014  from one position, such as engaged section  1026 , to disengaging sections  1022  and  1024 . As noted above, as a load, such as work machine  100  of  FIG.  1   , moves transversely in relation to a power source, there may be lengths of conductor rod  1000  that are not suitable for maintaining an electrical and physical connection between the load and the power source. The use of disengaging sections  1022  and  1024  and engaged section  1026  provide for the rotation of connector assembly  1004 . As piston conductor  1010  extends and retracts, retaining groove  1014  sets the rotational position of piston conductor  1010  caused by the position of retaining pin  1016  in retaining groove  1014 . Because piston conductor  1010  is mechanically connected to connector assembly  1004 , a rotation of piston conductor  1010  will cause a rotation of connector assembly  1004 . Thus, connector assembly  1004  will have a first orientation when retaining pin  1016  is in retaining groove  1014  while in engaged section  1026 . Further, connector assembly  1004  will have a second orientation different from the first orientation (disengaged) when retaining pin  1016  is in retaining groove  1014  outside of engaged section  1026 , such as disengaging sections  1022  and  1022 , shown in more detail in  FIGS.  11  and  12   , below. 
       FIG.  11    illustrates conductor rod  1000  in a disengaged orientation, in accordance with one or more examples of the present disclosure. In the disengaged orientation, illustrated by demarcation  1040  on the exterior of piston conductor  1010 , connector assembly  1004  is in a rotational configuration whereby power connectors, such as power connector  1006 , are rotationally positioned away from a horizontal position defined by axis X. It should be noted that a disengaged orientation means that connector assembly  1004  has rotated to a degree such that trailing arms and contactor attached to connector assembly  1004 , such as trailing arms  116  and contactor  118  of  FIG.  1   , are disengaged (physically or electrically disengaged) from a power rail. It should be noted that the disengaged orientation may be an electrical disengagement, a physical disengagement, or both. In  FIG.  11   , piston conductor  1010  is inserted within cylinder conductor  1008  so that retaining pin  1016  is positioned within retaining groove  1014  in disengaging section  1024 . It should be noted that demarcation  1040  on piston conductor  1010  is merely used to illustrate the rotation of piston conductor  1010 . 
       FIG.  12    illustrates conductor rod  1000  in an engaged orientation, in accordance with one or more examples of the presently disclosed subject matter. As illustrated in  FIG.  12   , piston conductor  1010  extracted from cylinder conductor  1008  at a greater distance than illustrated in  FIG.  11   . The extraction of piston conductor  1010  from an interior of cylinder conductor  1008  causes retaining pin  1016  to move from disengaged section  1024  of retaining groove  1014  and into engaged section  1026  of retaining groove  1014 . The movement of retaining pin  1016  through retaining groove  1014  into engaged section  1026  causes piston conductor  1010  to rotate about central axis RT extending the length of conductor rod  1000 , illustrated by the movement of demarcation  1040  from the position in  FIG.  11    to the position illustrated in  FIG.  12   . 
     In the engaged orientation of  FIG.  12    whereby retaining pin  1016  is in engaged section  1026  of retaining groove  1014 , connector assembly  1004  is in a rotational configuration. In a rotational configuration, power connectors, such as power connector  1006 , are rotationally positioned towards a horizontal position defined by axis X. It should be noted, however, that an engaged orientation is not limited to a horizontal orientation. As noted above in  FIG.  10   , an engaged orientation provides for connector assembly  1004  to be rotated to a degree such that trailing arms and contactor attached to connector assembly  1004 , such as trailing arms  116  and contactor  118  of  FIG.  1   , are engaged (physically or electrically disengaged) to a power rail. It should be noted that the engaged orientation may be an electrical engagement, a physical engagement, or both. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure provides a work machine powered electrically by an extendable and retractable conductor rod. The conductor rod has a barrel with an extendable arm axially moveable within the barrel. Both the barrel and the arm have tubular-shaped concentric conductors that slide against each other as the arm moves axially and maintain electrical conductivity for the electrical power from the power rails to the work machine. An axial passageway of open space passes through the centermost tubular-shaped conductors. Voids between selected conductors in the barrel and in the arm are filled with insulation so that a radial interface between the arm and the barrel is substantially solid, but for the axial passageway. 
     As noted above, an example work machine that is electrically powered generally includes an electric engine and a conductor rod  106 . The conductor rod  106  extends from head  122  proximate to the work machine  100  to a tip  124  spaced laterally from work machine  100 . A barrel  109  extending from head  122  toward tip  124  has cylinder tubes concentrically positioned around the central passageway and cylinder cavities between the cylinder tubes. An arm  110  extending from tip  124  toward head  122  has piston tubes concentrically positioned around the central passageway and piston cavities, where the cylinder tubes are radially offset from the piston tubes and arm  110  is slidably mated with barrel  109 . Cylinder conductors are maintained in both physical and electrical communication with their respective piston conductors using an electrical interface. As a result of the configurations described herein, electrical power may be maintained between a load and power source over various lengths between the load and the power source. For example, conductor rod  106  is extendable and retractable as work machine  100  moves closer to, or further away, from an electrical power source, thus maintaining the delivery of electrical power to work machine  100 . 
     Unless explicitly excluded, the use of the singular to describe a component, structure, or operation does not exclude the use of plural such components, structures, or operations or their equivalents. As used herein, the word “or” refers to any possible permutation of a set of items. For example, the phrase “A, B, or C” refers to at least one of A, B, C, or any combination thereof, such as any of: A; B; C; A and B; A and C; B and C; A, B, and C; or multiple of any item such as A and A; B, B, and C; A, A, B, C, and C; etc. 
     While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.