Abstract:
An axle tube comprising a dry section interposing a first wet section and a second wet section, the first and second wet sections housing a liquid lubricant, the dry section having an interior isolated from the liquid lubricant, at least one of the first and second wet sections includes a power train, and at least one of the first and second wet sections includes an electric motor, wherein the electric motor is at least partially received within the dry section, wherein a fluidic seal interposes the electric motor and the dry section, and wherein the electric motor is not rigidly mounted to the dry section.

Description:
FIELD OF THE INVENTION 
       [0001]    The present disclosure relates to managing an oil level in an axle or axle tube. 
       BACKGROUND OF THE INVENTION 
       [0002]    Oil is used as a lubricant and coolant for the components in an axle or axle tube. This coolant prevents over-heating and operates to increase the life of the components within the axle. But using a coolant that is in intimate contact with the components in the axle causes some challenges for service-ability. One challenge for service-ability is the fact that at least some of the oil must be drained to access the internal components. Moreover, the internal components must be compatible with the coolant and be able to be soaked in the coolant without the coolant causing significant degradation. Further, electrical connections within the axle become bathed in oil and impart difficulty (i.e., oily and slippery) in maintaining and changing worn connections. 
         [0003]    Additionally, mechanical contact of internal axle components to the axle frame across multiple points inherently transfers some vehicle load through the bearings and rotating components. As a result, this transfer of vehicle load necessitates that using more expensive bearings or shorter longevity of lesser expensive bearings. 
         [0004]    Because of this mechanical contact to separate and keep oil out of certain axle areas is undesirable should it lead to load transfer into bearings as this will lead to more expensive bearings and/or shorter life of bearings. 
       SUMMARY 
       [0005]    The exemplary embodiments of the present disclosure include an axle tube having at least one wet section and a dry section, where the two sections are mounted to one another, but the interior of the dry section is fluidicly isolated from the interior of the wet section. 
         [0006]    It is a first aspect of the present disclosure to provide an axle tube comprising: (a) a first enclosure having an interior occupied by a first portion of a first electric motor including electrical connections; (b) a first housing within which is located a second portion of the first electric motor; (c) a first seal interposing the first enclosure and the first electric motor, the first seal inhibiting fluid flow between the first enclosure and the first electric motor, where the first housing is mounted to the first enclosure and, where the first electric motor is not rigidly attached to the first housing. 
         [0007]    In a more detailed embodiment of the first aspect, the invention also includes the first enclosure having the interior occupied by a first portion of a second electric motor including electrical connections, a second housing within which is located a second portion of the second electric motor, a second seal interposing the first enclosure and the second electric motor, the second seal inhibiting fluid flow between the first enclosure and the second electric motor, where the second housing is mounted to the first enclosure and, where the second electric motor is not rigidly attached to the first housing. In yet another more detailed embodiment, the first electric motor includes an electrical connection end opposed from a drive shaft end, the first housing includes an orifice for throughput of the electrical connection end of the first electric motor and, the orifice is sized to inhibit complete throughput of the drive shaft end of the first electric motor. In a further detailed embodiment, the first housing includes a first orifice for throughput of at least the first portion of the first electric motor, the first housing includes a second orifice for throughput of at least a first portion of a second electric motor and, the first orifice is opposite the second orifice. In still a further detailed embodiment, the housing includes a through hole to concurrently access the first portion of the first electric motor and the first portion of the second electric motor. In a more detailed embodiment, the housing includes an air supply line coupled to the first electric motor and extending outside the housing. In a more detailed embodiment, the housing includes a lubricant supply line coupled to the first electric motor and extending outside the housing. In another more detailed embodiment, the housing includes an air supply line coupled to the first electric motor and extending outside the housing and, the housing includes a lubricant supply line coupled to the first electric motor and extending outside the housing. In yet another more detailed embodiment, the first enclosure is sealed. 
         [0008]    It is a second aspect of the present invention to provide an axle tube comprising a dry section interposing a first wet section and a second wet section, the first and second wet sections housing a liquid lubricant, the dry section having an interior isolated from the liquid lubricant, at least one of the first and second wet sections includes a power train, and at least one of the first and second wet sections includes an electric motor, wherein the electric motor is at least partially received within the dry section, wherein a fluidic seal interposes the electric motor and the dry section, and wherein the electric motor is not rigidly mounted to the dry section. 
         [0009]    In a more detailed embodiment of the second aspect, the dry section is fluidicly separated from the interior of the first and second wet sections and, the dry section is sealed to egress of contaminants into its interior. In yet another more detailed embodiment, the dry section comprises a rectangular cross-section and, where at least one of the first wet section and the second wet section has a generally circular cross-section. In a further detailed embodiment, the dry section includes a pair of orifices opposite one another for accommodating partial throughput of two respective electric motors and, the dry section includes a third orifice providing access to the interior of the dry section after the electric motors are occupying the pair of orifices. In still a further detailed embodiment, the third orifice is occupied by at least one of an air supply line and a lubricant supply line in fluid communication with an interior of at least one of the two electric motors. 
         [0010]    It is a third aspect of the present invention to provide a method of fabricating an axle tube, the method comprising: (a) including a dry section along the length of an axle tube when fabricating the axle tube, the axle tube fabricated to include a wet section housing a liquid lubricant and an electric motor, and an interior of the dry section is free from liquid lubricant from the wet section; and, (b) floating at least a portion of the electric motor upon a seal, the seal interposing the dry section and the electric motor, where the electric motor is not rigidly mounted to the dry section. 
         [0011]    In a more detailed embodiment of the third aspect, the axle tube is fabricated to include at least two wet sections, the axle tube is fabricate so the dry section interposes at least two of the wet sections and, an interior of the dry section is fluidicly sealed from the at least two wet sections interposed. In yet another more detailed embodiment, the method further includes welding a housing to the dry section, the housing at least partially enclosing the electric motor and, where the electric motor, housing, and dry section cooperate to create a lubricant reservoir cavity. In a further detailed embodiment, the method further includes installing at least one of an air supply line and a lubricant supply line to the electric motor, the supply line being in fluid communication with an interior of the electric motors, wherein the supply line extends though the interior of the dry section and outside of the interior of the dry section. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is an elevated perspective view, from the top, of an exemplary axle tube in accordance with the instant disclosure, shown without external fluid and electrical lines. 
           [0013]      FIG. 2  is an elevated perspective view, from the bottom, of the exemplary axle tube in  FIG. 1 . 
           [0014]      FIG. 3  is a cross-sectional view of the exemplary axle tube in  FIG. 1 . 
           [0015]      FIG. 4  is an elevated perspective view, from the top, of the exemplary dry center section of  FIG. 1 . 
           [0016]      FIG. 5  is an elevated perspective view, from the bottom, of the exemplary dry center section of  FIG. 4 . 
           [0017]      FIG. 6  is an elevated perspective view, from the front, of the exemplary dry center section of  FIG. 1  without a pair of walls and showing the pair of electric motors mounted to the dry center section. 
           [0018]      FIG. 7  is an elevated perspective view, taken from the electric motor side, of a cross-section taken with respect to the transmission subsection and the motor subsection housing to show the position of the electric motor with respect to adjacent components. 
           [0019]      FIG. 8  is an elevated perspective view, taken from the transmission side, of a cross-section taken with respect to the transmission subsection to show the position of the electric motor and tube with respect to adjacent components. 
           [0020]      FIG. 9  is a schematic diagram showing the level of lubricant within the exemplary axle tube of  FIG. 1  prior to start-up. 
           [0021]      FIG. 10  is a schematic diagram showing the level of lubricant within the exemplary axle tube of  FIG. 1  at start-up. 
           [0022]      FIG. 11  is a schematic diagram showing the level of lubricant within the exemplary axle tube of  FIG. 1  subsequent to start-up after the air pressure within the subsections is great enough to displace a greater amount of lubricant into a reserve cavity. 
           [0023]      FIG. 12  is an elevated perspective view, from the top, of an exemplary axle tube in accordance with the instant disclosure shown with external fluid lines. 
           [0024]      FIG. 13  is a magnified view of a portion of  FIG. 12 . 
           [0025]      FIG. 14  is an exemplary flow diagram for the axle tube shown in  FIG. 12 . 
           [0026]      FIG. 15  is an exemplary flow diagram for an alternate exemplary axle tube. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    The exemplary embodiments of the present disclosure are described and illustrated below to encompass axle tubes and methods of managing fluid levels within an axle tube. Of course, it will be apparent to those of ordinary skill in the art that the exemplary embodiments discussed below are merely examples and may be reconfigured without departing from the scope and spirit of the present disclosure. However, for clarity and precision, the exemplary embodiments as discussed below may include optional steps, methods, and features that one of ordinary skill should recognize as not being a requisite to fall within the scope of the present invention. 
         [0028]    Referencing  FIGS. 1-3 , a first exemplary axle tube  100  (shown without external fluid hoses) includes a dry center section  102  and corresponding right and left wet sections  104 ,  106  mounted to opposing ends of the dry center section. In this exemplary embodiment, each right and left wet section  104 ,  106  includes two subsections  108 ,  110 . The first subsection  108  is a motor subsection that houses the majority of an electric motor  112 . The second subsection  110  is a transmission subsection and includes transmission components  114  operatively coupled to the electric motor  112 . Both the right and left wet sections  104 ,  106  are sealed in order to retain oil concurrently lubricating and cooling the transmission components  114  and cooling the electric motor  112 . Both of the wet sections  104 ,  106  include seals that are operative to retard the inflow of water and other contaminants. 
         [0029]    Referring to  FIGS. 1-6 , the dry center section  102  comprises an enclosure formed by six rectangular walls  230 ,  232 ,  234 ,  236 ,  238 ,  240  that are mounted to one another. Each of the six walls  230 ,  232 ,  234 ,  236 ,  238 ,  240  corresponds to another of the remaining five walls so that corresponding pairs of walls are generally uniformly spaced apart and oriented in parallel. This orientation provides a box-shaped enclosure that defines a dry interior cavity  246 . 
         [0030]    The first corresponding pair of walls  230 ,  234  (right and left) each include a circular through hole  250  large enough to receive a dry portion  252  of an electric motor  112 . As will be discussed in more detail hereafter, the vast majority of the electric motor  112  is housed within the motor subsection  108 . Respective elastomeric ring seals  260  interposes an outer housing  262  of each electric motor  112  and an outside surface  264  of each wall  230 ,  234 . In particular, the elastomeric ring seal  260  has a diameter that is greater than the diameter of the through hole  250  so that the ring seal circumscribes the through hole, but is mounted to the outside surface  264  of each wall  230 ,  234 . In particular, the outside surface  264  includes a circular recess  266  that bounds the through hole  250  and provides a seat for a portion of the ring seal  260 . It should be noted that the housing  262  of each electric motor  112  is concurrently mounted to the seal ring  260 , but is not rigidly fastened to the dry center section  102 . Rather, the electric motor  112  floats with respect to the dry center section  102  because of the flexibility of the seal rings  260  interposing the walls  230 ,  234  and the housing  262  of each electric motor  112 . 
         [0031]    The second corresponding pair of walls  232 ,  236  (front and back) are coupled to the right and left walls  230 ,  234  and to the third corresponding pair of walls  238 ,  240  (top and bottom). Each front and back wall  232 ,  236  includes a plurality of orifices  270  adapted to provide a mounting location for attaching the axle tube to a vehicle frame (not shown), thereby providing support to the center of the axle tube. The top and bottom walls  238 ,  240  each include a rounded, rectangular through hole  272 . In this exemplary embodiment, the rounded, rectangular through hole  272  of the bottom wall  238  is closed off by a rounded rectangular pan  276  mounted to an exterior surface  278  thereof. In particular, the rounded rectangular pan  276  includes a plurality of orifices (not shown) adapted to receive threaded fasteners  280  that extend through the orifices and into holes of the bottom wall  240  in order to allow the pan to be coupled and uncoupled from the bottom wall. In contrast, the rounded, rectangular through hole  272  of the top wall  238  is not entirely closed off. Instead, a rounded rectangular pan  284  having a pair of elongated rectangular openings  286  is mounted to an outer surface of the top wall  238 . As with the bottom pan  276 , the top pan  284  includes a plurality of orifices (not shown) adapted to receive threaded fasteners  290  that extend through the orifices and into holes of the top wall  238  to couple and uncouple the top pan from the top wall. Extending from the top pan  284  and circumscribing the elongated rectangular openings  286  are adapter boxes  294 . Each adapter box  294  receives a high voltage subassembly (not shown) that is pre-connected and fluidicly sealed in order to establish electrical communication from outside the dry center section  102  and into communication with the electric motors  112  partially located within the dry center section. The adapter boxes  294  also provide connection locations for the air, oil and low voltage lines (not shown) that connect to the electric motors  112 . The top pan  284  also includes a plurality of secondary orifices  296  that interpose the adapter boxes  294 . 
         [0032]    The dry portion  252  of each electric motor  112  includes numerous connections that provide electrical and fluid communication to the internal components of the electric motor and the transmission components  114 . Several electrical connections  300  are provided in order to supply electric current to the internal components. Those skilled in the art are familiar with the structure of electric motors and a corresponding detailed discussion of the internal components of each electric motor has been omitted only to further brevity. In addition to the electrical connections  300 , the dry portion  252  also includes an oil supply fitting  302  near the bottom of the dry portion for introducing oil into the interior of the electric motor  112 . And an air supply fitting  304  is also provided as part of the dry portion  252  near the top of the dry portion in order to introduce air into the interior of the electric motor  112 . 
         [0033]    Referring to  FIGS. 1 and 7 , the remainder of the electric motor  112  is housed within a tube  310  of the motor subsection  108 . The tube  310  comprises a dual ply  312 ,  314  cylinder having a series of fluid connections  316  that allow for fluid communication between the interior of the tube and an exterior of the tube. As will be discussed in more detail hereafter, the fluid connections  316  are coupled to hoses (see  FIGS. 12 and 13 ). In between the interior ply  314  of the tube  310  and the exterior of the electric motor housing  262  is a reserve cavity  318  that is used to store excess oil when the axle tube  100  is in operation. Both tube  310  plies  312 ,  314  are welded at one longitudinal end to the outside surface  264  of respective walls  230 ,  234 . 
         [0034]    Referencing  FIGS. 7 and 8 , the opposite longitudinal end of each tube  310  is welded to a circular flange  320  having a plurality of through holes. A first circumferentially outermost set of holes  322  receive fasteners in order to mount the flange  320  to a corresponding flange  360  of the transmission subsection  110 . A second inner circumferential set of holes (not shown) receive fasteners  324  in order to mount the flange  320  to an end plate  330  of the electric motor  112 . A gasket  332  interposes the flange  320  and the end plate  330  to ensure a fluid tight seal therebetween. 
         [0035]    The end plate  330  includes several holes having varying functionality. A first set of holes receive the fasteners  324  in order to mount the electric motor  112  to the flange  320 . A second set of through holes  336  provide communication across the end plate  330 . As will be discussed in more detail hereafter, these holes  336  provide a pathway for fluid (e.g., coolant/lubricant, such as oil) to flow between the interior of the transmission subsection  110  and the reserve cavity  318 . In order to manipulate the flow of fluid between the interior of the transmission subsection  110  and the reserve cavity  318 , the end plate  330  also includes a through hole  338  elevated above an output shaft  340  from the electric motor  112  and above the second set of through holes  336 . The through hole  338  is adapted to provide a pathway for fluid (e.g., air) to flow between the interior of the transmission subsection  110  and the electric motor housing  262 . In this manner, as air pressurizes the interior of the transmission subsection  110  and the interior of the electric motor housing  262 , coolant/lubricant is forced into the reserve cavity  318 . 
         [0036]    Referring to  FIGS. 9-11 , a schematic diagram shows the transmission subsection  110  and the motor subsection  108  coupled to one another and fluidicly sealed. In this manner, lubricant/coolant (e.g., oil)  400  is able to flow between the subsections  108 ,  110 , but the subsections generally maintain the same aggregate volume (subsection  108  plus subsection  110 ) of lubricant/coolant. And the amount of lubricant/coolant  400  located within either subsection  108 ,  110  changes depending upon whether the axle tube  100  is operable or not. 
         [0037]    Referencing  FIGS. 7-9 ), initially, as the axle tube  100  becomes operable (upon receiving electric current to drive the electric motors  112  and an air supply, and upon being on level ground), the level of lubricant/coolant  400  within the subsections  108 ,  110  is generally the same. This universal level is the result of lubricant/coolant  400  freely flowing between the subsections through the second set of through holes  336  of the end plate  330  (see  FIGS. 7 and 8 ). More specifically, the level of lubricant/coolant  400  is the same in the transmission subsection  110 , the reserve cavity  318 , and in the internal cavity  350  of the electric motor  112 . But this universal level does not stay the same during operation of the axle tube  100 . 
         [0038]    Referring to  FIGS. 6-8  and  10 , after the axle tube  100  becomes operable (upon receiving electric current to drive the electric motors  112  and an air supply (e.g., air source  572  in  FIG. 14 ), and upon being on level ground), air is fed into the internal cavity  350  of the electric motor  112  by way of the air supply fitting  304  within the dry portion  252 . The air within the internal cavity  350  of the electric motor  112  builds in pressure based upon the air supply providing air above atmospheric pressure. In exemplary form, the air supply provides air at approximately forty pounds per square inch gauge (psig), which is reduced before it reaches the air supply fitting  304 . The air pressure within the electric motor  112  may be, for example, between 0.4-1.0 psig to overcome the head pressure within the reserve cavity  318  and force oil out of the interior of the electric motor through a drain  352  at the base of the electric motor housing  262 . Eventually, as the air drives out all or almost all of the lubricant  400  within the interior  350  of the electric motor  112 , air begins to escape through the drain  352  and into the reserve cavity  318 , where it is vented via a vent  580 . In this manner, the air pressure within the interior  350  of the electric motor  112  may be self-regulated. In addition, as the air pressure builds within the internal cavity  250 , the air escapes through the through hole  338  of the end plate  330  that is elevated above the output shaft  340 . Thus, the air pressure across the through hole  338  is relatively the same. This means that the air pressure within the internal cavity  350  of the electric motor  112  is the same as the air pressure within the transmission subsection  110 . Because of this equalization of pressure, the level of lubricant/coolant  400  across the through holes  336  is generally the same in the transmission subsection  110  and in the internal cavity  350  of the electric motor  112 . But it should also be noted that the transmission subsection  110  includes a retainer wall  354  operative to retain a predetermined level of lubricant  400  within a portion of the transmission subsection that is above the level of lubricant across the through holes  336 . And the level of lubricant within the reserve cavity  318  is also higher than the level of lubricant across the through holes  336 . 
         [0039]    Referencing  FIG. 11 , as the air pressure builds within the transmission subsection  110  and the internal cavity  350  of the electric motor  112 , the higher pressure air begins to displace the lubricant/coolant  400  within these areas. As air displaces the lubricant/coolant  400 , the corresponding level of lubricant/coolant  400  within the transmission subsection  110  and the internal cavity  350  drops and the lubricant/coolant is forced into the reserve cavity  318 , thus causing the level of lubricant/coolant to drastically increase—well above the level within the transmission subsection and the internal cavity  350  of the electric motor  112 . Eventually, the level of lubricant/coolant  400  within the transmission subsection  110  and the internal cavity  350  reaches an operating level as an equilibrium is established between the air pressure pushing on the lubricant/coolant and the pressure of the lubricant/coolant pushing back on the air. This operating level of lubricant/coolant  400  is determined, in large part, based upon the operating pressure of the air supply. However, those skilled in the art will realize that the operating level of lubricant/coolant  400  may change and, thus, the air pressure supplied by the air supply may also change to accommodate for these changes in the operating level of the lubricant/coolant. 
         [0040]    When the axle tube  100  no longer is operable (not electric current to drive the electric motors  112  and no air supply, and upon being on level ground), the level of lubricant/coolant  400  within the subsections  108 ,  110  returns to being uniform (see  FIG. 9 ). Specifically, without the air pressure forcing the lubricant/coolant  400  into the reserve cavity  318 , the pressure of the lubricant/coolant within the reserve cavity operates to displace the air and become evenly distributed among the subsections  108 ,  110 . 
         [0041]    Referencing  FIGS. 11-14 , the lubricant/coolant  400  flows through a closed loop  500  that includes the interior of the subsections  108 ,  110  and a series of interconnected conduits. Each tube  310  includes an exit orifice defined by an exit orifice fitting  502  that is positioned near the lowest arcuate location on the tube. The exit orifice fitting  502  is mounted to a rigid outlet conduit  504  that is mounted to a flexible outlet conduit  506 . In this way, the fitting  502  and conduits  504 ,  506  cooperate provide sealed flow for lubricant/coolant  400  exiting the reserve cavity  318  and flowing to the end of the outlet conduit  506 . Each end of both flexible outlet conduits  506  is coupled to a T-fitting  508  operative to consolidate the dual flows into a single flexible line  514 . This flexible line  514  is operatively coupled to a pump  516  that forces the lubricant/coolant  400  into a discharge flexible conduit  520  that carries the lubricant/coolant to be cooled and cleaned. 
         [0042]    Lubricant/coolant  400  is carried by the flexible conduit  520  and directed into a radiator  526 , which has a second fluid flowing therethrough to lower the temperature of the lubricant/coolant. After the lubricant/coolant  400  has been cooled, a radiator outlet conduit  528  conveys the lubricant/coolant to a filter  530 . The filter  530  is operative to remove contaminants from the lubricant/coolant  400  and discharge clean lubricant/coolant into a feed conduit  534 . 
         [0043]    The feed conduit  534  is coupled to a manifold  536  that operates to distribute the lubricant/coolant  400  among several input conduits  540 ,  542 . The first pair of input conduits  540  are each coupled to a rigid conduit  548  that is coupled to an entrance orifice fitting  550  that defines an entrance orifice. The entrance orifice fitting  550  is mounted to the flange  360  of the transmission subsection  110  and provides an egress point for lubricant/coolant  400  to flow into the interior of the transmission subsection. The second pair of input conduits  542  extends through the secondary orifices  296  (see  FIG. 5 ) of the top pan  284  and into communication with the oil supply fitting  302  of the electric motor  112  (see  FIG. 6 ), thereby providing an egress point for lubricant/coolant  400  to flow into the interior of the electric motor. 
         [0044]    Direct fluid communication between the motor subsections  108  is made possible by a communication line  560  that is coupled to respective outlet fittings  562  mounted to the tube  310  at locations elevated with respect to the exit orifice fittings  502 . In this manner, lubricant/coolant  400  is freely able to flow between one reserve cavity  318  (see  FIG. 7 ) to the other reserve cavity. The communication line  560  comprises two mirror image sections of rigid line (that generally retains its shape) that are coupled to a box fitting  563 . The box fitting  563  is coupled to a by-pass conduit  564  that is also coupled to the manifold  536 . In this manner, if the input conduits  540 ,  542  become damaged or blocked, the manifold recognizes the resulting pressure difference (greater or lesser) and diverts the lubricant/coolant  400  from the manifold  536  into the by-pass conduit  564 , where the lubricant/coolant is directed into the respective reserve cavities  318  using the communication line  560 . Otherwise, the by-pass conduit  564  contains stagnant lubricant/coolant  400 . And, as shown in part in  FIGS. 10 and 11 , an air supply conduit  570  provides air from an air source  572  to the air supply fitting  304  of the electric motor  112 . Exemplary air sources include, without limitation, turbochargers and air compressors. In this exemplary embodiment, it is envisioned that the axle tube  100  is included as part of a larger machine having an internal combustion engine with a turbocharger, where at least a portion of the discharged, compressed air from the turbocharger is routed through the air supply conduit  570 . It should also be noted that the tube  310  includes a vent  580  that may be operatively coupled to a vent line (not shown) in order to vent air within the reserve cavity  318  as the amount of lubricant/coolant  400  increases, and at the same time allow air into the reserve cavity as the amount of lubricant/coolant decreases. 
         [0045]    Referring to  FIG. 15 , an additional diagram depict alternate closed loop flow path  600  for the lubricant/coolant  400 . In this alternate closed loop  600 , the conduits and components are the same as the first closed loop  500  with the exception of providing an air source  572  or an air supply conduit  570 . In such a circumstance, the lubricant/coolant  400  within the subsections  108 ,  110  is not actively managed to direct more lubricant/coolant to the reserve cavities  318  when the electric motor  112  and transmission components are operational. 
         [0046]    It should be noted that while the foregoing embodiment have discussed using compressed air to increase the level of lubricant/coolant  400  within the reserve cavity  318 , it is also within the scope of the disclosure to apply suction to the top of the reserve cavity to pull additional lubricant/coolant within the reserve cavity. In such a circumstance, the vent  580  may be couple to a suction line (not shown) that operates to create a low pressure area within the reserve cavity  318  to raise the level of lubricant/coolant  400 . 
         [0047]    Following from the above description and invention summaries, it should be apparent to those of ordinary skill in the art that, while the methods and apparatuses herein described constitute exemplary embodiments of the present invention, the invention contained herein is not limited to this precise embodiment and that changes may be made to such embodiments without departing from the scope of the invention as defined by the claims. Additionally, it is to be understood that the invention is defined by the claims and it is not intended that any limitations or elements describing the exemplary embodiments set forth herein are to be incorporated into the interpretation of any claim element unless such limitation or element is explicitly stated. Likewise, it is to be understood that it is not necessary to meet any or all of the identified advantages or objects of the invention disclosed herein in order to fall within the scope of any claims, since the invention is defined by the claims and since inherent and/or unforeseen advantages of the present invention may exist even though they may not have been explicitly discussed herein.