Drive assembly with passive pump lubrication

Abstract

A drive assembly includes a housing, upper and lower shafts, friction stacks, and a pair of meshing gears. The housing defines a container containing a volume of lubricating fluid, a brake chamber, the brake chamber having a metering hole in a lower portion of the brake chamber, and an exit port at an upper portion of the brake chamber. The upper and lower shafts are at different elevations within the housing and are configured to rotate. The friction stacks are within the brake chamber and are driven to rotate by the upper shaft. The pair of meshing gears are driven to rotate by one or more of the upper and lower shafts, and the gears convey lubricating fluid from the container to the lower portion of the brake chamber through the metering hole. The rotation of the friction stacks pumps the lubricating fluid to the exit port at the upper portion of the brake chamber.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] not applicable.

[0003] STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0004] not applicable. Field of the Invention

[0005] The present disclosure relates generally to work vehicles and, more particularly, to lubricating transmission systems and other components of work vehicles. Background Art

[0006] In the agricultural, construction, and forestry industries, among other industries, work vehicles include drive assemblies for driving various components of the machine, including various drivetrain components for driving wheels, tracks, or other propulsion members responsible for moving the work vehicle along the ground. It is important that such drive assemblies remain adequately lubricated to inhibit the adverse effects associated with various types of wear. Various active lubrication systems have dedicated pumps, valves, and other components to control the distribution of lubricating fluid to wear and heat generating areas of the machine. In certain situations where the target area is in close proximity to a source of lubricating fluid, certain passive lubrication techniques (e.g., splash lubrication) may be used, thereby saving the cost and complexity associated with active lubrication systems. Summary of the invention

[0007] The present disclosure provides a drive assembly with passive pump lubrication, wherein lubrication fluid is pumped to components of the drive assembly without a dedicated pump.

[0008] In one aspect, a drive assembly is provided and includes a housing, upper and lower shafts, friction stacks, and a pair of meshing gears. The housing defines a container containing a volume of lubricating fluid, a brake chamber, the brake chamber having a metering hole in a lower portion of the brake chamber, and an exit port at an upper portion of the brake chamber. The upper and lower shafts are at different elevations within the housing and are configured for rotation. The friction stacks are within the brake chamber and are driven to rotate by the upper shaft. The pair of meshing gears are driven to rotate by one or more of the upper and lower shafts, and the gears convey lubricating fluid from the container to the lower portion of the brake chamber through the metering hole. The rotation of the friction stacks pumps the lubricating fluid to the exit port at the upper portion of the brake chamber.

[0009] In another aspect, a drive assembly is provided and includes a housing, an upper shaft and a lower shaft, a friction stack and a pair of meshing gears. The housing defines a container containing a volume of lubricating fluid and defines a brake chamber having a metering hole in a lower portion of the brake chamber and an exit port at an upper portion of the brake chamber. The upper and lower shafts are at different elevations within the housing and are configured to rotate. The friction stack is within the brake chamber and is driven to rotate by the upper shaft. The pair of meshing gears is driven to rotate by one or more of the upper and lower shafts. The gears convey lubricating fluid from the container to the lower portion of the brake chamber through the metering hole. The rotation of the friction stack pumps the lubricating fluid to the exit port, through the exit port, and into an axial passage defined by the upper shaft.

[0010] The details of one or more embodiments are set forth in the accompanying drawings and the following description. The components in the drawings are not necessarily drawn to scale, but emphasis is placed on illustrating the principles of the present disclosure. Other features and advantages will become apparent from the specification, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is an elevation view of an example of a work vehicle including an example of a drive assembly;

[0012] Figure 2 yes Figure 1 A perspective view of a drive assembly in FIG.

[0013] Figure 3 yes Figure 2 A top plan view of the drive assembly in FIG.

[0014] Figure 4 It is along Figure 3 A side cross-sectional view taken along line 4-4 in FIG.

[0015] Figure 5 yes Figure 4 an enlarged view of area 5-5 of the cross-sectional view;

[0016] Figure 6 It is along Figure 3 an end cross-sectional view taken along line 6-6 in FIG.

[0017] Figure 7 yes Figure 2 A partial perspective view of an example of a portion of a drive assembly shown in;

[0018] Figure 8 It is along Figure 3 A partial cross-sectional view taken along line 8-8 in FIG.

[0019] Fig. 9 yes Figure 2 a side elevation view of a portion of a drive assembly shown in , with a portion of the drive assembly removed;

[0020] Fig.10 It is along Figure 3 Another side cross-sectional view taken along line 10-10 in FIG. 1 ; and

[0021] Fig.11 yes Figure 2 A perspective view of an exemplary pin and cap arrangement of a drive assembly in FIG.

[0022] Like reference numbers in the various drawings indicate like elements. DETAILED DESCRIPTION

[0023] One or more exemplary embodiments of the disclosed drive assembly with passive pump lubrication are described below, as shown in the accompanying drawings of the drawings briefly described above. Various modifications to the exemplary embodiments may be anticipated by those skilled in the art.

[0024] As used herein, unless otherwise limited or modified, a list having elements separated by conjunction terms (e.g., "and") and also preceded by the phrase "one or more of" or "at least one of" indicates a configuration or arrangement that potentially includes the individual elements of the list or any combination thereof. For example, "at least one of A, B, and C" or "one or more of A, B, and C" indicates the possibility of only A, only B, only C, or any combination of two or more of A, B, and C (e.g., A and B; B and C; A and C; or A, B, and C).

[0025] In addition, in detailing the present disclosure, directional and orientation terms may be used, such as, for example, "forward", "front", "rearward", "rear", "lateral", "horizontal", and "vertical". Such terms are defined at least in part relative to the direction in which the work vehicle or tool travels during use. For example, the terms "forward" and "front" (including "in front of" and any other derivatives and variations) refer to directions corresponding to the main direction of travel, while the terms "rearward" and "rear" (and derivatives and variations) refer to the opposite direction. The term "longitudinal axis" may also refer to an axis extending in the front and rear directions. In contrast, the term "lateral axis" may refer to an axis that is perpendicular to the longitudinal axis and extends in a horizontal plane (i.e., a plane containing the longitudinal axis and the transverse axis). The term "vertical" as it appears herein refers to an axis or direction that is orthogonal to the horizontal plane containing the front-rear axis and the transverse axis. In addition, the term "lubricating fluid" as used herein refers to any suitable liquid or semi-liquid (e.g., mixed with a gas or a flowable granular solid) that is used to lubricate and / or cool machine parts (e.g., gears, shafts, etc.). Thus, it will be understood that a "lubricating fluid" may be used for lubrication or cooling alone, or for both lubrication and cooling.

[0026] Typically, a work vehicle includes various drive assemblies for driving various components and attachment tools of a machine. For example, a propulsion transmission system may include one or more drive assemblies (e.g., final drives) that are used to rotate wheels, sprockets, or other mechanisms to move the work vehicle along the ground or terrain. The drive assembly typically has various moving parts that require sufficient lubrication to ensure the correct operation and life of the drive assembly. Without proper lubrication and cooling, the gears, shafts, friction laminations, etc. of the drive assembly may experience excessive heat, wear, and fatigue, thereby reducing the life expectancy of (multiple) components and potentially causing premature failure of components and the overall drive assembly. It is particularly difficult to lubricate components of the drive assembly located in a remote location (e.g., a higher elevation) or in a confined space within the drive assembly. Conventional methods can incorporate one or more pumps to actively control the pumping of a lubricating fluid as needed to lubricate components such as these. Incorporating such one or more pumps increases the cost, weight, and complexity of the overall assembly, and additional components that are prone to failure are provided in addition.

[0027] The present disclosure provides for pumping lubricating fluid in a passive manner without additional pumps, valves, pipelines or channels, and control devices. The present disclosure uses existing components of the assembly to deliver lubricating fluid to a target area of ​​the assembly. The lubricating fluid is not only delivered passively, but also pumped passively (i.e., moved under the action of a force, such as by a local pressure difference). Passive pumping can be established at one or more discrete pumping areas.

[0028] The present invention can also passively pump lubricating fluid from a lower elevation area of ​​the assembly to a higher elevation area of ​​the assembly. In various embodiments, the components and techniques of the present disclosure can deliver lubricating fluid from a lower reservoir or sump in which the lubricating fluid is stored or collected in the housing of the assembly to a rotating component at an upper area in the housing. For example, the lubricating fluid can be carried to a higher elevation in the housing by one or more components that are connected (e.g., physically contacted or partially immersed) with the lubricating fluid in the sump. Then, the lubricating fluid can be carried or otherwise delivered (e.g., splashed) to one or more components that passively impart a pumping action to the lubricating fluid. Therefore, the pumping action distributes the lubricating fluid strongly to one or more components at a higher elevation in the housing. Additionally or alternatively, the assembly can be configured to pump the lubricating fluid to a remote location in the housing to deliver the lubricating fluid to components in a distant and / or confined space contained in the housing. Therefore, the passive pumping action can be guided in directions other than the higher elevation (e.g., typically in the direction of the same or lower elevation).

[0029] Too much lubrication of the components in the drive assembly may also cause problems due to excessive friction losses (e.g., windage) encountered by moving parts. Therefore, conventional systems may have avoided passive lubrication technology because it cannot provide a control level commensurate with active lubrication systems. The components and technologies disclosed herein solve this problem by providing passive metering control of lubricating fluid. In various embodiments, the lubricating fluid passes through one or more metering holes of one or more controlled sizes before reaching the target component. In this way, the lubricating fluid can flow to the target component with a controlled flow rate and / or volume. When the components are housed in a dedicated compartment or other confined space, (multiple) metering openings can be sized and positioned to control the collection or collection of lubricating fluid so that the target component can obtain sufficient reserves while limiting the volume of the collected lubricating fluid to a level lower than that which would cause excessive friction losses (e.g., windage) and related operational inefficiencies.

[0030] The following discussion of one or more exemplary embodiments of the components and methods disclosed herein may sometimes focus on exemplary applications of a drive assembly configured to drive tracks to propel a tracked bulldozer along terrain. In other examples, the drive assembly may have different configurations and may be incorporated into other applications. In some embodiments, for example, the drive assembly may be used with other types of work vehicles in agriculture, construction, forestry, or other off-road industries. In addition, although the various exemplary embodiments described herein relate to drive assemblies in the context of propulsion of work vehicles, it should be understood that the disclosed assemblies and methods may also be applied to stationary drive assemblies or drive assemblies in work vehicles that are used to drive components (e.g., various work tools, etc.) for purposes other than propulsion.

[0031] One or more exemplary embodiments of the disclosed drive assembly utilized in a work vehicle are described below, as shown in the accompanying drawings of the drawings briefly described above. In general, the disclosed drive assembly (and the work vehicle in which they are implemented) provides improved lubrication of the drive assembly compared to conventional systems and arrangements.

[0032] Reference now Figure 1 , an example of a work vehicle 20 is illustrated in the form of a crawler bulldozer having a work tool 32 in the form of a blade. The work vehicle 20 includes a cab 24, an engine compartment 28, a work tool 32, and a propulsion member 36. The cab 24 can have many configurations and is the location of the work vehicle 20 occupied by the operator. The cab 24 can include, for example, controls, displays, actuators, etc. that can be manipulated by the operator to control the operation of the work vehicle 20. The engine compartment 28 can have many configurations and generally contains drive components, such as a motor or engine for providing the necessary power to the various components of the work vehicle 20. In one example, the engine can be a diesel-powered internal combustion engine. Other components associated with the engine can also be at least partially housed or contained in the engine compartment 28.

[0033] The work vehicle 20 may have various propulsion members for moving the work vehicle 20 along terrain. The type of propulsion member(s) used with the work vehicle may depend on the type of terrain and / or the type of work being performed by the work vehicle 20. In the illustrated example, the propulsion members are endless tracks 36, with one endless track 36 on each of the right and left sides of the work vehicle 20. In other examples, the propulsion members may be other types of propulsion members, including, but not limited to, ground engaging wheels. The exemplary work vehicle 20 includes a drive assembly 40 in the form of a final drive coupled to each track 36 via a sprocket 41. The drive assembly 40 is configured to drive the tracks 36 and provide braking capability to the tracks 36. In one example, the braking capability includes a parking brake assembly 72 (see Figure 4 ).

[0034] Also refer to Figure 2 and Figure 3, illustrates an example of a drive assembly 40. Although the work vehicle 20 includes multiple drive assemblies 40, only one drive assembly 40 will be described herein, wherein it should be understood that the structure and functionality of the drive assembly 40 can be applied to other drive assemblies of the work vehicle 20. In one example, the drive assembly 40 may include a mounting plate 44 for coupling the drive assembly 40 to the work vehicle 20, a rotatable drive member 48 coupled to the track 36, and a housing 52 between the mounting plate 44 and the drive member 48. The housing 52 may be an integral component or formed in one or more components (e.g., Figure 5 52A and 52B) shown in FIG. 5 , however, for simplicity, it will be referred to as housing 52 hereinafter. Drive member 48 can have a variety of configurations to cooperate with the desired type of propulsion member. In one example, drive member 48 is a cylindrical drum configured to mount a sprocket 41 for common rotation, sprocket 41 having teeth received in the open spaces of the links of track 36.

[0035] Also refer to Figures 4 to 6 , the drive assembly 40 can include a first shaft or lower shaft 56 rigidly coupled to and rotatable with the drive member 48, a first gear or large gear 60 rigidly coupled to and rotatable with the first shaft 56, a second gear 64 meshing with the first gear 60, and a second shaft or upper shaft 68 rigidly coupled to and rotatable with the second gear 64. In one example, the upper shaft 68 is disposed in the drive assembly 40 at a higher elevation than the lower shaft 56. The rotating component of the brake assembly 72 can be coupled to the second shaft 68, and the end 76 of the second shaft 68 can be splined so as to be coupled to the output (e.g., drive shaft) of the engine of the work vehicle 20. In one example, the engine of the work vehicle 20 drives or rotates the second shaft 68 via a spline connection 80, and the second shaft 68 rotates the second gear 64. The second gear 64 rotates the first gear 60 at the gear mesh 50, and the first gear 60 rotates the first shaft 56, which in turn rotates the drive member 48. Rotation of drive member 48 causes tracks or other propulsion members 36 to rotate or move, thereby moving work vehicle 20 along the terrain.

[0036] The drive assembly 40 defines a brake chamber 84, and the brake assembly 72 is at least partially positioned in the brake chamber 84. In one example, the brake assembly 72 is a wet friction plate parking brake and can include a friction stack 88 composed of a plurality of friction discs or plates 92. Each of the plurality of friction plates 92 can be generally circular in shape, can define an opening through a center thereof, and can include an inner diameter 96 and an outer diameter 100. In one example, a first set of friction plates (or separator plates) 92A can be rigidly coupled to the interior of the brake chamber 84 at its outer diameter 100 and remain stationary, while a second set of friction plates (or friction discs) 92B can be connected to the second shaft 68 at its inner diameter 96 and rotate with the second shaft 68 relative to the first set of friction plates 92A. In some examples, the first set of friction plates 92A and the second set of friction plates 92B alternate with each other in the friction stack 88. A plurality of features, such as grooves or recesses, are defined in either or both of the first set of friction plates 92A and the second set of friction plates 92B to allow lubricating liquid or fluid to pass between the respective sets of friction plates 92A, 92B. In some examples, to actuate the brake assembly 72, pressure is applied to the brake assembly 72 to cause the first set of friction plates 92A and the second set of friction plates 92B to be compressed together, thereby providing resistance to rotation of the rotating set of friction plates 92B, as described above, the friction plates 92B resist rotation of the second shaft 68 and interconnecting components.

[0037] Also refer to Figure 7 and Figure 8 In one example, the housing 52 of the drive assembly 40 can define a lubricant container or sump 104 configured to hold a supply of lubricating fluid 108. In one example, the first gear 60 is partially immersed in the lubricating fluid 108 present in the sump 104. As the first gear 60 rotates, the first gear 60 carries the lubricating fluid thereon upward and from the supply of lubricating fluid toward the second gear 64. At the gear mesh 50 of the first gear 60 and the second gear 64, the lubricating fluid 108 is forced, flung, splashed, or otherwise dispersed away from the gear mesh 50 (by Figure 5 As indicated by arrow 112 in FIG. Figure 5 As shown in FIG. 1 , the lubricating fluid 108 is dispersed in multiple outward directions from the gear mesh 50 between the first gear 60 and the second gear 64. In one example, the lubricating fluid 108 moves from the gear mesh 50 to the right (eg, Figure 5) is captured by the collection basin 116. In one example, the collection basin 116 can be coupled to the housing 52 and can define a basin container 120 that is configured to hold a certain amount of lubricating fluid. In one example, a metering hole 124 is defined through the housing 52 and is in fluid communication with the collection basin 116 and the brake chamber 84. In one example, the metering hole 124 is in fluid communication with the lower portion 128 of the brake chamber 84 and is configured to deliver the lubricating fluid to the inner diameter 96 of the friction plate 92. In one example, the longitudinal rotational axis 132 extends through the center of the second shaft 68 and can be used to define a lower portion 128 of the brake chamber 84 (the lower portion 128 is the portion of the brake chamber 84 below the longitudinal rotational axis 132) and an upper portion 136 of the brake chamber 84 (the upper portion 136 is the portion of the brake chamber 84 above the longitudinal rotational axis 132). In other examples, the upper and lower portions of brake chamber 84 may be defined in other ways, and all such possibilities are intended to be within the spirit and scope of the present disclosure.

[0038] Continue to refer Figures 4 to 8 In one example, the metering hole 124 is sized and shaped to meter or allow a desired and appropriate amount of lubricating fluid to be delivered from the sump 116 to the lower portion 128 of the brake chamber 84 and to the inner diameter 96 of the friction plate 92. The metering hole 124 may be of any size and shape depending on the lubrication requirements of the brake assembly 72. An insufficient amount of lubricating fluid in the drive assembly 40 may allow excessive friction on the components of the drive assembly and reduce the life of the components. In addition, excessive lubricating fluid in the drive assembly 40 may create excessive windage on the components of the drive assembly 40. In one example, the metering hole 124 may be between about one-eighth of an inch and about three-quarters of an inch at its maximum width or maximum diameter. In another example, the metering hole 124 may be between about one-quarter of an inch and about three-quarters of an inch at its maximum width or maximum diameter. In another example, the metering hole 124 may be about half an inch at its maximum width or maximum diameter.

[0039] Special References Figure 5 , Fig. 9 and Fig.10In one example, the rotation of the second shaft 68 and the second set of friction plates 92B can pump, force, or otherwise move the lubricating fluid from the inner diameter 96 of the friction plates 92 to the outer diameter 100 of the friction plates 92 due to the centrifugal force caused by the rotation of the second set of friction plates 92B and the friction force interacting with the lubricating fluid. In one example, a pair of exit ports 140 can be defined in the housing 52 of the brake assembly 72 in the upper portion 136 of the brake chamber 84 and can be aligned with or positioned near the outer diameter 100 of the friction plates 92. In other examples, any number of exit ports 140 can be defined in the housing 52, including one and more than two. In other examples, one or more exit ports 140 can be defined in the upper portion 136 and the lower portion 128 of the brake chamber 84. In yet other examples, one or more exit ports 140 can be defined only in the lower portion 128 of the brake chamber 84. Returning to the illustrated example, one end 144 of each of the exit ports 140 can receive lubricating fluid from the outer diameter 100 of the friction plate 92. In one example, the friction plate 92A in the friction stack 88 can include one or more anti-rotation protrusions, splines, or tabs 148 that can also be used to direct the lubricating fluid into the exit ports 140. The lubricating fluid can move away from the friction plate 92 through the exit ports 140 and downward into the lubricating fluid reservoir 152. In one example, the lubricating fluid reservoir 152 is defined between a wall or surface 156 of the housing 52 of the drive assembly 40 and a cap 160 coupled to the end of the second shaft 68 and a bearing assembly 164 that at least partially facilitates rotation of the second shaft 68 relative to the housing 52.

[0040] Reference now Fig.10 and Fig.11In one example, the second shaft or upper shaft 68 can define an axial passage 168 therethrough. In one example, the pin 172 can be axially aligned with the axial passage 168 and at least partially positioned in the axial passage 168. The pin 172 can be hollow and can define a pin cavity 176 therein. In one example, an opening or slot 180 can be defined along the length of the pin 172 and communicate with the pin cavity 176. In one example, the axial passage 168 can include a first portion 184 having a first diameter and a second portion 188 having a second diameter, wherein the first portion 184 has a larger diameter than the second portion 188. In such an example, the pin 172 is positioned in the first portion 184 of the axial passage 168 such that the second shaft 68 is configured to rotate relative to the pin 172 without engaging or interfering with the pin 172. In this example, the pin cavity 176 can have a smaller diameter than the second portion 188 of the axial passage 168. With the pin 172 positioned in one end of the second shaft 68, the slot 180 in the pin 172 is positioned in the upper half of the pin 172. In one example, the cap 160 can include a central opening 192 configured to receive the pin 172 therein and hold the pin 172 in a fixed orientation. In one example, the cap 160 includes a protrusion or key 196 defined in the central opening 192 of the cap 160, the protrusion or key 196 being positioned in the slot 180 of the pin 172 to hold the pin 172 in a fixed orientation relative to the cap 160 and the second shaft 68. In this configuration, the second shaft 68 is configured to rotate relative to the cap 160 and the pin 172.

[0041] The lubricating fluid accumulates in the lubricating fluid reservoir 152 and flows, moves, is pumped or otherwise passed from the lubricating fluid reservoir 152 through the slit 180 in the pin 172 and into the pin cavity 176. The lubricating fluid reservoir 152 can be of any size and shape to hold a desired and / or appropriate amount of lubricating fluid. The lubricating fluid flows, moves, is pumped or otherwise transferred from the pin cavity 176 into the axial passage 168. The rotation of the second shaft 68 places the lubricating fluid under centrifugal forces, which throw the lubricating fluid toward the wall 200 of the axial passage 168. As the lubricating fluid accumulates in the axial passage 168, the lubricating fluid wants to flow out of the axial passage. Because the pin 172 is positioned in one end of the axial passage 168 and has a reduced diameter, thereby resisting or inhibiting flow in the direction of the pin 172, the lubricating fluid flows in the opposite direction toward the second end of the axial passage 168. At the second end of the axial passage 168, the lubricating fluid can lubricate the splines 204 defined in the second shaft 68, wherein the engine output of the work vehicle can be coupled to the second shaft 68. Without proper lubrication between the second shaft 68 and the engine output, wear can occur between the second shaft 68 and the engine output. The lubricating fluid passing through the axial passage 168 toward the splines 204 can provide a sufficient amount of lubrication to inhibit wear between the second shaft 68 and the engine output.

[0042] Also refer to Fig.10 In one example, a drain port 208 can be defined in the housing 52 of the drive assembly 40, can be in communication with the sump 104, and can allow the lubricating fluid to return to the sump 104 after the lubricating fluid exits the axial passage 168 of the second shaft 68. The lubricating fluid exits the second shaft 68, falls to a lower elevation than the second shaft 68 under the action of gravity, enters the drain port 208, exits the drain port 208, and falls under the action of gravity into the sump 104 where the supply of lubricating fluid 108 is stored. In one example, the drain port 208 is defined in the housing 52 at a lower elevation than the metering orifice 124. In some examples, a plurality of drain ports 208 can be defined in the housing 52 of the drive assembly 40. One or more drain ports of the present disclosure can be configured and defined in the drive assembly 40 in any manner to allow the lubricating fluid to return to the sump 104, and all such possibilities are intended to be within the spirit and scope of the present disclosure.

[0043] The drive assembly 40 of the present disclosure is capable of passively pumping lubricating fluid therein without the use of a separate pump and associated valves, lines, and controls. That is, the components of the drive assembly 40 and the operation of such components provide the pumping action required to pump the lubricating fluid through the drive assembly 40 to the target component. In the illustrated example, the operation of the brake assembly 72 imparts the necessary forces (e.g., centrifugal forces and frictional forces) to the lubricating fluid to pump the lubricating fluid from the lower portion 128 of the brake chamber 84 to the inner diameter 96 of the friction plate 92 radially outward from the longitudinal rotation axis 132, and to passively pump the lubricating fluid upward to a higher elevation within the housing 52 against gravity, where it can be directed to the second shaft 68 by gravity. In addition, in the illustrated example, a second pumping action is provided to passively pump the lubricating fluid through the axial channel 168 in the second shaft 68. The reduced diameter at the connection of the pin 172 not only inhibits the flow of lubricating fluid toward the pin, but also, as the second shaft 68 rotates, the centrifugal force acting on the lubricating fluid achieves a passive pumping action, which pumps the lubricating fluid to the second end of the axial passage 168 to lubricate the splines 204 due to the pressure increase achieved at the relatively smaller opening area at the pin 172 compared to the opposite end of the second shaft 68.

[0044] In addition, the following examples are provided and are numbered for ease of reference as follows:

[0045] 1. A drive assembly comprising: a housing defining a container containing a volume of lubricating fluid and defining a brake chamber having a metering hole in a lower portion of the brake chamber and an exit port at an upper portion of the brake chamber; an upper shaft and a lower shaft at different elevations within the housing and configured for rotation; a friction stack within the brake chamber and driven to rotate by the upper shaft; and a pair of meshing gears driven to rotate by one or more of the upper and lower shafts, the gears conveying lubricating fluid from the container to the lower portion of the brake chamber through the metering hole; wherein rotation of the friction stack pumps the lubricating fluid to the exit port at the upper portion of the brake chamber.

[0046] 2. The drive assembly according to Example 1 is characterized in that the housing defines a collecting basin below the metering hole for collecting the lubricating fluid splashed from the meshing gears, and the collected lubricating fluid is connected to the metering hole.

[0047] 3. A drive assembly according to Example 1, characterized in that the upper shaft has a rotation axis extending longitudinally through its center; and wherein the exit port of the brake chamber is above the rotation axis.

[0048] 4. The drive assembly of example 3, wherein the exit port is one of a plurality of exit ports at an upper portion of the brake chamber.

[0049] 5. The drive assembly according to Example 1, characterized in that the lubricating fluid flows from the brake chamber into the exit port, and flows out from the exit port and into the axial channel through the upper shaft.

[0050] 6. The drive assembly of example 5, wherein rotation of the upper shaft pumps the lubricating fluid through and out of the axial passage.

[0051] 7. The drive assembly according to Example 5 further includes a discharge port, which is at a lower elevation than the metering hole and is connected to the container, wherein the discharge port allows lubricating fluid that has left the axial passage of the upper shaft to be discharged into the container.

[0052] 8. The drive assembly according to Example 5 further includes a lubricating fluid reservoir between the exit port and the axial channel, wherein the lubricating fluid reservoir contains a certain volume of lubricating fluid that has left the exit port and before flowing into the axial channel.

[0053] 9. The drive assembly according to Example 8 further includes a pin, which is axially aligned with the axial channel and defines an opening therein that communicates with the lubricating fluid reservoir and the axial channel, wherein the lubricating fluid in the reservoir passes through the opening in the pin to flow into the axial channel.

[0054] 10. A drive assembly comprising: a housing defining a container containing a volume of lubricating fluid and defining a brake chamber having a metering hole in a lower portion of the brake chamber and an exit port at an upper portion of the brake chamber; an upper shaft and a lower shaft at different elevations within the housing and configured for rotation; a friction stack within the brake chamber and driven to rotate by the upper shaft; and a pair of meshing gears driven to rotate by one or more of the upper and lower shafts, the gears conveying lubricating fluid from the container to the lower portion of the brake chamber through the metering hole; wherein rotation of the friction stack pumps the lubricating fluid to the exit port, through the exit port, and into an axial passage defined by the upper shaft.

[0055] 11. The drive assembly according to Example 10 is characterized in that the housing defines a collecting basin below the metering hole for collecting the lubricating fluid splashed from the meshing gears, and the collected lubricating fluid is connected to the metering hole.

[0056] 12. The drive assembly of example 10 wherein the friction laminations have an inner diameter and an outer diameter, and wherein the metering holes meter lubricating fluid to the inner diameter of the friction laminations.

[0057] 13. The drive assembly of example 12 wherein the exit port is one of a plurality of exit ports proximate an outer diameter of the friction stack.

[0058] 14. The drive assembly of example 10, wherein rotation of the upper shaft pumps the lubricating fluid through and out of the axial passage.

[0059] 15. The drive assembly according to Example 10 further includes a lubricating fluid reservoir between the exit port and the axial channel, wherein the lubricating fluid reservoir contains a certain volume of lubricating fluid that has left the exit port and before flowing into the axial channel.

[0060] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. Unless the context clearly indicates otherwise, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms. It will be further understood that the terms "comprises" and / or "comprising" when used in this specification specify the presence of stated features, wholes, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, parts and / or groups thereof.

[0061] The description of the present disclosure has been presented for the purpose of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present disclosure. The embodiments and examples explicitly referenced herein are selected and described to best explain the principles of the present disclosure and its practical application, and to enable other persons of ordinary skill in the art to understand the present disclosure and recognize many substitutions, modifications and variations to the described examples. Therefore, various embodiments and implementations other than those explicitly described are within the scope of the following claims.

Claims

1. A drive assembly, comprising: a housing defining a reservoir containing a volume of lubricating fluid and defining a brake chamber having a metering orifice in a lower portion of the brake chamber and an exit port at an upper portion of the brake chamber; an upper shaft and a lower shaft, the upper shaft and the lower shaft being located at different heights within the housing and configured to rotate; a friction stack within the brake chamber and driven to rotate by the upper shaft; and a pair of meshing gears rigidly coupled to the upper and lower shafts, respectively, and driven for rotation by one or more of the upper and lower shafts, the gears conveying lubricating fluid from the reservoir to a lower portion of the brake chamber through the metering orifice; wherein rotation of the friction stack pumps lubricating fluid to an exit port at an upper portion of the brake chamber, The housing defines a liquid collecting basin below the metering hole for collecting the lubricating fluid splashed from the meshing gear, and the collected lubricating fluid is connected to the metering hole.

2. The drive assembly according to claim 1, characterized in that: The friction stack includes a projection that directs the lubrication fluid away from the friction stack to an exit port of the brake chamber.

3. The drive assembly according to claim 1, characterized in that: The friction stack is a parking brake component.

4. The drive assembly according to claim 3, characterized in that: The parking brake assembly has an inner diameter and an outer diameter, and wherein the metering hole meters lubrication fluid to the inner diameter of the parking brake assembly.

5. The drive assembly according to claim 1, characterized in that: The upper shaft has a rotational axis extending longitudinally through a center of the upper shaft; and Wherein, the exit port of the brake chamber is above the rotation axis.

6. The drive assembly according to claim 5, characterized in that: The exit port is one of a plurality of exit ports at an upper portion of the brake chamber.

7. The drive assembly according to claim 1, characterized in that: The lubricating fluid flows from the brake chamber into the exit port, and flows out from the exit port and into the axial passage through the upper shaft.

8. The drive assembly according to claim 7, characterized in that: Rotation of the upper shaft pumps the lubrication fluid through and out of the axial passage.

9. The drive assembly of claim 7, further comprising a discharge port at a lower level than the metering orifice and communicating with the container, wherein The drain port allows lubrication fluid that has exited the axial passage of the upper shaft to drain into the container.

10. The drive assembly of claim 7, further comprising a lubricating fluid reservoir between the exit port and the axial passage, wherein: The lubrication fluid reservoir contains a volume of lubrication fluid that has exited the exit port and prior to flowing into the axial passage.

11. The drive assembly of claim 10, further comprising a pin axially aligned with the axial passage and defining an opening therein in communication with the lubricating fluid reservoir and the axial passage, wherein: Lubricating fluid in the reservoir flows into the axial passage through the opening in the pin.

12. A drive assembly comprising: a housing defining a reservoir containing a volume of lubricating fluid and defining a brake chamber having a metering orifice in a lower portion of the brake chamber and an exit port at an upper portion of the brake chamber; an upper shaft and a lower shaft, the upper shaft and the lower shaft being at different heights within the housing and configured to rotate; a friction stack within the brake chamber and driven to rotate by the upper shaft; and a pair of meshing gears rigidly coupled to the upper and lower shafts, respectively, and driven for rotation by one or more of the upper and lower shafts, the gears conveying lubricating fluid from the reservoir to a lower portion of the brake chamber through the metering orifice; wherein rotation of the friction stack pumps lubrication fluid to the exit port, through the exit port, and into an axial passage defined through the upper shaft, The housing defines a liquid collecting basin below the metering hole for collecting the lubricating fluid splashed from the meshing gear, and the collected lubricating fluid is connected to the metering hole.

13. The drive assembly according to claim 12, characterized in that The friction stack has an inner diameter and an outer diameter, and wherein the metering holes meter lubrication fluid to the inner diameter of the friction stack.

14. The drive assembly according to claim 13, characterized in that The exit port is one of a plurality of exit ports proximate an outer diameter of the friction stack.

15. The drive assembly according to claim 12, characterized in that Rotation of the upper shaft pumps the lubrication fluid through and out of the axial passage.

16. The drive assembly of claim 15, further comprising a discharge port in communication with the container, wherein: The drain port allows lubrication fluid that has exited the axial passage to drain into the container.

17. The drive assembly of claim 12, further comprising a lubricating fluid reservoir between the exit port and the axial passage, wherein: The lubrication fluid reservoir contains a volume of lubrication fluid that has exited the exit port and prior to flowing into the axial passage.

18. The drive assembly of claim 17, further comprising a pin axially aligned with the axial passage and defining an opening therein in communication with the lubricating fluid reservoir and the axial passage, wherein Lubricating fluid in the reservoir flows into the axial passage through the opening in the pin.

Images