Patent Publication Number: US-2021179170-A1

Title: Motor drive assembly for a dual path electric powertrain of a machine

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to a powertrain of a machine and, for example, to a motor drive assembly for a dual path electric powertrain of a machine. 
     BACKGROUND 
     An electric powertrain or drive may be used as a source of driving power in a machine, such as, for example, a track-type tractor (e.g., an excavator, a bulldozer, and/or the like). The electric powertrain may drive, using power provided by an internal combustion engine, ground engaging elements of the machine to cause the machine to move. Using the electric powertrain to supplement the internal combustion engine may reduce emissions generated during operation of the machine and may increase fuel efficiency of the machine. In operation, the electric powertrain may generate an output torque that is transferred to ground engaging components on the machine (e.g., such as tracks on a track-type tractor). 
     Generally, an electric powertrain for a relatively large machine (e.g., a machine with an operational mass over 45,000 kilograms (kg)) requires certain minimum performance capabilities and/or performance standards that enable a certain level of steering responsiveness, drawbar pull, propulsion power, retarding power, and/or the like for operations of the machine. Furthermore, to meet such performance capabilities and/or performance standards, previous designs and/or configurations of motor drive assemblies for electric powertrains of machines that include a single motor on each drive element of the machine may result in motor drive assemblies that are physically too large to fit within a desired compartment and/or configuration of the machine (e.g., in association with certain desired packaging, inertia, weight, cost, and/or the like). 
     One approach for an electric powertrain for a work machine is disclosed in U.S. Pat. No. 7,950,481 that issued to Betz et al. on May 31, 2011 (“the &#39;481 patent”). In particular, the &#39;481 patent discloses two electric motors respectively coupled to driving members and power electronics that control the two electric motors such that the two electric motors may operate in a coordinated manner to propel the work machine. Furthermore, the &#39;481 patent discloses braking devices configured to selectively apply a braking force resulting in a slowing of either or both driving members. 
     The motor drive assembly of the present disclosure provides one or more additional benefits to solve one or more of the problems set forth above and/or one or more other problems in the art. 
     SUMMARY 
     According to some implementations, a motor drive assembly for a machine may include a final drive assembly to engage a ground engaging element of the machine; an electric motor to provide torque to the final drive assembly; a planetary gear assembly mechanically coupled to a rotor shaft of the electric motor and an axle of the final drive assembly; and a brake assembly to engage a component of the planetary gear assembly to retard the rotor shaft and the axle. 
     According to some implementations, a dual path electric powertrain for a machine may include a first motor drive assembly that is positioned toward a first lateral side of the machine, the first motor drive assembly including a first final drive assembly to engage a first ground engaging element of the machine, a first electric motor to provide torque to the first final drive assembly, a first planetary gear assembly mechanically coupled to a first rotor shaft of the first electric motor and a first axle of the first final drive assembly, and a first brake assembly to engage a component of the first planetary gear assembly to retard the first rotor shaft and the first axle; and a second motor drive assembly positioned toward a second lateral side of the machine that is opposite the first lateral side, the second motor drive assembly being coaxially aligned with the first motor drive assembly and including: a second final drive assembly to engage a second ground engaging element of the machine, a second electric motor to provide torque to the second final drive assembly, a second planetary gear assembly mechanically coupled to a second rotor shaft of the second electric motor and a second axle of the second final drive assembly, and a second brake assembly to engage a component of the second planetary gear assembly to retard the second rotor shaft and the second axle. 
     According to some implementations, a machine may include a power source; and a dual path electric powertrain powered by the power source, the dual path electric powertrain including: a left-side motor drive assembly positioned on a left-side of the machine, the left-side motor drive assembly including: a left-side final drive assembly to drive a left-side track of the machine, a left-side electric motor to provide torque to the left-side final drive assembly, a left-side planetary gear assembly mechanically coupled to a left-side rotor shaft of the left-side electric motor and a left-side axle of the left-side final drive assembly, and a left-side brake assembly to engage the left-side planetary gear assembly to retard the left-side rotor shaft and the left-side axle; and a right-side motor drive assembly positioned on a right-side of the machine, the right-side motor drive assembly being coaxially aligned with the left-side motor drive assembly and including: a right-side final drive assembly to drive a right-side track of the machine, a right-side electric motor to provide torque to the right-side final drive assembly, a right-side planetary gear assembly mechanically coupled to a right-side rotor shaft of the right-side electric motor and a right-side axle of the right-side final drive assembly, and a right-side brake assembly to engage the right-side planetary gear assembly to retard the right-side rotor shaft and the right-side axle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of an example machine in which an example motor drive assembly described herein may be implemented. 
         FIG. 2  is an isometric view of an example dual path electric powertrain that may be implemented, as described herein, within the machine of  FIG. 1 . 
         FIG. 3  is a diagram of an example motor drive assembly that may be implemented within the dual path electric powertrain of  FIG. 2 . 
         FIG. 4  is a top view of an example dual path electric powertrain within an example frame of the machine of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a side view of an example machine  100  (shown as a track-type tractor) in which a dual path electric powertrain described herein may be implemented. 
     As shown in  FIG. 1 , machine  100  may include a frame  105  that encloses and/or supports a power source (e.g., an internal combustion engine) and/or one or more components of a dual path electric powertrain described herein. For example, machine  100  may include an engine, a generator, an inverter, and/or one or more electrical lines, fluid lines, and/or the like to control motor drive assemblies of the dual path electric powertrain to drive final drive assemblies  110  of machine  100 . 
     A generator includes a device that converts mechanical energy into electrical energy for use in an electrical system of machine  100  (e.g., the dual path electric powertrain, a battery, and/or the like). Such mechanical energy may be provided by the power source of machine  100  to power motor drive assemblies of the dual path electric powertrain and/or received from motor drive assemblies (e.g., during braking and/or retarding operation) of machine  100  for storage in a battery of machine  100  and/or use in one or more other electrical systems of machine  100 . 
     An inverter may include one or more electrical devices or components that manipulate electrical power of an electrical system of machine  100 . For example, the inverter may filter (or clean) and/or route electrical power to motor drive assemblies of the dual path electric powertrain, to a battery, and/or to one or more other electrical systems of machine  100 . In this way, power and/or current may flow from the generator to the inverter (e.g., to control power to the motor drive assemblies) and/or from the motor drive assemblies to the inverter (e.g., to absorb power from the motor drive assemblies). 
     Machine  100  may include one or more electronic control modules (ECMs) that control the power of the dual path electric powertrain described herein. For example, an ECM may include a processor and/or memory component to control the dual path electric powertrain described herein according to one or more inputs (e.g., from an operator station of machine  100 ), one or more conditions of machine  100  (e.g., as sensed by one or more sensors of machine  100 ), and/or the like. 
     A motor drive assembly of the dual path electric powertrain may include a final drive assembly  110 , on each side  115  of machine  100 , that is mechanically configured to engage and/or support a ground engaging element  120  (e.g., a track chain, a wheel, or other type of ground engaging element). Accordingly, movement of machine  100  may correspond to rotation of final drive assemblies  110  and, correspondingly, ground engaging elements  120 . In the example of  FIG. 1 , machine  100  includes a blade  125  (e.g., to move ground material or other substances). As described herein, ground engaging elements  120  may include a set of tracks. A dual path electric powertrain, as described herein, may provide propulsion and braking capabilities for machine  100  with a threshold blade width to track gauge ratio (e.g., when a between 1.0 and 3.0). A track gauge may correspond to a distance between a center line of each track of a track-type tractor. 
     As indicated above,  FIG. 1  is provided as an example. Other examples may differ from what is described in connection with  FIG. 1 . In some implementations, machine  100  may include additional components, fewer components, different components (e.g., a different implement other than blade  125 ), or differently arranged components than those shown in  FIG. 1 . 
       FIG. 2  is an isometric view of an example dual path electric powertrain  200  that may be implemented, as described herein, within machine  100  of  FIG. 1 . As shown in  FIG. 2 , frame  205  (shown with dashed lines, and corresponding to frame  105 ) forms an electric motor cavity  210  that is axially situated between frame mounts  212  (shown as “ 212 - 1 ” and “ 212 - 2 ”) on a left-side  214 - 1  and right-side  214 - 2  of frame  205 . Electric motor cavity  210  may be a compartment of frame  205  formed beneath a support structure  216  of frame  205  that is configured to provide structural integrity to frame  205  and/or support one or more components or systems of machine  100  (e.g., an operator station). Dual path electric powertrain  200  includes two motor drive assemblies  220  (shown as, and referred to herein, individually as a “left motor drive assembly  220 - 1 ” and a “right motor drive assembly  220 - 2 ”) mounted, via frame mounts  212 , to frame  205 . 
     Motor drive assemblies  220  enable dual path electric powertrain  200  via a set of modular components. In  FIG. 2 , the modular components include motor assemblies  230  (shown as and referred to herein as a “left motor assembly  230 - 1 ” and a “right motor assembly  230 - 2 ”), brake assemblies  240  (shown as and referred to herein as a “left brake assembly  240 - 1 ” and a “right brake assembly  240 - 2 ”), and final drive assemblies  250  (shown as and referred to herein as a “left final drive assembly  250 - 1 ” and a “right final drive assembly  250 - 2 ”). 
     Left motor drive assembly  220 - 1  is shown mounted (e.g., with fasteners such as bolts for mechanical attachment, with electrical connections being connected, with fluid passageways being joined, and/or the like) to a left-side  214 - 1  of frame  205  such that a motor housing of left motor assembly  230 - 1  is positioned within electric motor cavity  210 , and brake assembly  240 - 1  is positioned outside of electric motor cavity  210 . Similarly, right motor drive assembly  220 - 2  is shown mounted to a right-side  214 - 2  of frame  205  such that a motor housing of right motor assembly  230 - 2  is positioned within electric motor cavity  210 , and right brake assembly  240 - 2  is positioned outside of electric motor cavity  210 . Accordingly, in the example of  FIG. 2 , other than mounting flanges  232  (shown as “ 232 - 1 ” and “ 232 - 2 ”) of the motor assemblies  230 , the remainder of the motor housings of motor assemblies  230  are within a bore (e.g., an opening of frame  205  that receives a motor drive assembly  220 ) of frame  205  and/or electric motor cavity  210 . 
     According to some implementations, brake assemblies  240  of motor drive assemblies  220  may be included within electric motor cavity  210 . The position of brake assemblies  240  may be based on a design and/or dimensions of components of a configuration of motor drive assemblies  220  described herein, a design and/or configuration of machine  100 , and/or the like. For example, for relatively smaller machines (e.g., machines with an operating mass of less than 60,000 kg) motor assemblies  220  may be configured to have brake assemblies  240  positioned within electric motor cavity  210 , relatively medium sized machines (e.g., machines with an operating mass between 60,000 kg and 100,000 kg), motor drive assemblies  220  may be configured to have brake assemblies  240  either positioned within electric motor cavity  210  or outside of electric motor cavity (e.g., depending on a size and/or shape of frame  205 ), and for relatively larger machines (e.g., machines with an operating mass greater than 100,000 kg) motor assemblies  220  may be configured to have brake assemblies positioned outside of electric motor cavity  210 . Such positioning of brake assemblies  240  in various machines  100  may depend on axial lengths of motors of motor assemblies  230  and an axial width of electric motor cavity  210 . 
     Left motor drive assembly  220 - 1  may be coaxially aligned with right motor drive assembly  220 - 2 . For example, a rotor shaft of left motor assembly  230 - 1  may be coaxially aligned with a rotor shaft of right motor assembly  230 - 2 . Additionally, or alternatively, an axle of left final drive assembly  250 - 1  may be coaxially aligned with an axle of right final drive assembly  250 - 2 . Accordingly, as shown, motor drive assemblies  220  may be adjacently aligned with one another when mounted within frame  205  for operation of machine  100 . 
     In some implementations, left motor drive assembly  220 - 1  can be a same type of motor drive assembly as right motor drive assembly  220 - 2 . Correspondingly, left motor assembly  230 - 1 , left brake assembly  240 - 1 , and left final drive assembly  250 - 1  may be a same type of motor assembly, brake assembly, and final drive assembly as right motor assembly  230 - 2 , right brake assembly  240 - 2 , and right final drive assembly  250 - 2 , respectively. Multiple components may be considered to be a same type based on being associated with a same make/manufacture, being identified by a same model number (or serial number, part number, etc.), having the same dimensions, having the same design or performance specifications, and/or the like. 
     As indicated above,  FIG. 2  is provided as an example. Other examples may differ from what is described in connection with  FIG. 2 . In some implementations, dual path electric powertrain  200  may include additional components (e.g., a clutch system, such as a slip clutch), fewer components, different components, or differently arranged components than those shown in  FIG. 2 . 
       FIG. 3  is a diagram of an example motor drive assembly  300  that may be implemented within dual path electric powertrain  200  of  FIG. 2 . Motor drive assembly  300  may correspond to left motor drive assembly  220 - 1  and/or right motor drive assembly  220 - 2 . 
     As used herein, components are “mechanically coupled” when the components are attached to (e.g., fastened to, fit to, adhered to, and/or the like via one or more fasteners, couplings, bearing assemblies, and/or the like) and/or in contact with one another indirectly via one or more intervening parts, or directly (without any intervening components other than fasteners or couplings that connect the components). Further, as used herein, components are “mechanically connected” when the components are attached to one another and/or in contact with one another without any intervening components (other than fasteners or couplings). 
     Motor drive assembly  300  includes a motor assembly  302  that includes an electric motor  304 , a motor housing  306  with a motor mounting flange  308  (e.g., corresponding to mounting flange  232 ), a rotor  310  with a rotor shaft  312 , and a stator  314 . Electric motor  304  may be a switched reluctance motor that provides mechanical power (e.g., rotational mechanical power) via rotor shaft  312  (e.g., to drive ground engaging element  120  of machine  100 ) and/or absorbs rotational power from rotor shaft  312  (e.g., when electric motor  304  is performing as a generator to provide electrical energy to an electrical system of machine  100 ). Rotor  310  may have a length to diameter (L/D) ratio between 0.5 and 2.2, where the length and the diameter correspond to a lamination stack length and a lamination diameter of rotor  310 . 
     Motor drive assembly  300  includes a final drive assembly  316  that includes a final drive  318 , a final drive housing  320  with a drive mounting flange  322 , an axle  324  (e.g., an input shaft of final drive  318 ), and a sprocket  326  that is configured to engage with ground engaging element  120 . Final drive  318  may include one or more final drive gear assemblies (e.g., positioned within final drive housing  320 ) that provide a gear reduction between rotations of axle  324  and sprocket  326 . 
     Motor drive assembly  300  includes a gear assembly  328  with a sun gear  330 , one or more planet gears  332 , a ring gear  334 , and a carrier  336 . As shown, gear assembly  328  includes a sun-in, carrier-out planetary gear assembly. Gear assembly  328  may provide a gear reduction (e.g., a gear reduction between 2.5 and 6.5) between rotational speeds rotor of shaft  312  (and correspondingly, sun gear  330 ) and carrier  336 . 
     Motor drive assembly  300  includes brake assembly  338  with a brake pack  340 , a brake housing  342  with a spring retainer plate  344 , a brake spring  346 , and a brake piston  348 . Brake assembly  338  may include a wet disc brake assembly that is configured to retard (or provide retarding power) rotation of rotor shaft  312  and axle  324  (and, correspondingly, ground engaging element  120  of machine  100 ). For example, brake spring  346  may be configured to apply a force against brake piston  348 , which is situated between brake pack  340  and brake spring  346 . Accordingly, when brake piston  348  is controlled to reduce a force against brake spring  346 , brake spring  346  is able to apply a force (e.g., through brake piston  348 ) to brake pack  340  (e.g., to compress brake pack  340  to slow rotation of (and/or provide a retarding force on) rotor shaft  312  and axle  324 ). Alternatively, brake piston  348 , when controlled to apply force against brake spring  346  may reduce or remove any force against brake pack  340  (e.g., to permit rotation of rotor shaft  312  and axle  324 ). 
     As shown in  FIG. 3 , electric motor  304  is configured within motor drive assembly  300 , such that when motor drive assembly  300  is mounted to frame  105  of machine  100 , electric motor  304  is within electric motor cavity  210 . Electric motor  304  may be configured as a high torque switched reluctance motor that is capable of providing torque to rotor shaft  312  to enable movement of machine  100 . For example, electric motor  304 , according to the configuration of motor drive assembly  300 , may provide enough torque to satisfy one or more performance requirements associated with machine  100 , as described herein. 
     Gear assembly  328  operates according to rotation of rotor shaft  312  and/or axle  324 . As shown, rotor shaft  312  extends from motor housing  306  beyond motor mounting flange  308  to engage with sun gear  330  (e.g., via splines of rotor shaft  312  and/or gear teeth of sun gear  330 ). Furthermore, sun gear  330  is mechanically coupled to planet gears  332 , which are mechanically coupled to ring gear  334 . Carrier  336 , of gear assembly  328 , is mechanically connected to planet gears  332  (e.g., carrier  336  may be fit within bearing assemblies associated with planet gears  332 ) and axle  324  (e.g., via one or more splines of axle  324  and/or carrier  336 ). Accordingly, torque from rotor shaft  312  may cause gear assembly  328  to drive axle  324  (e.g., to drive ground engaging element  120 ), and torque from axle  324  may cause gear assembly  328  to drive rotor shaft  312  (e.g., to enable electric motor  304  to generate electrical energy). 
     As shown, gear assembly  328  is fit within brake housing  342  (e.g., or enclosed within brake housing  342  between spring retainer plate  344  and motor mounting flange  308 ). Accordingly, gear assembly  328  may be axially positioned between motor mounting flange  308  of motor assembly  302  and spring retainer plate  344  of brake assembly  338 . In some implementations, ring gear  334  is fixed (or splined) relative to a gear reaction hub of brake assembly  338 . For example, ring gear  334  may be fixed or splined with brake housing  342  (e.g., to prevent rotation of ring gear  334  when sun gear  330  and/or planet gears  332  are rotating) and/or spring plate  344 . As shown, gear assembly  328  is positioned within brake housing  342 , toward final drive assembly  316  relative to brake pack  340 . Accordingly, rotor shaft  312  extends through a component of brake housing  342  that supports brake pack  340  to enable brake pack  340  to engage a component of gear assembly  328  to provide retarding power to motor drive assembly  300 . 
     Brake pack  340  is configured to engage with a component of gear assembly  328  to retard rotation of rotor shaft  312  and/or axle  324  (e.g., to enable performance of a braking operation, a steering operation, and/or the like). For example, brake pack  340  may include a set of friction discs and a set of separator plates. Each friction disc, of the set of friction discs, is situated between pairs of separator plates or between a separator plate and brake housing  342 . The friction plates may be mechanically connected to carrier  336 , and, therefore, may rotate in accordance with a rotation of carrier  336 . In other examples, the friction plates of brake pack  340  may be mechanically connected to sun gear  330  and/or ring gear  334  (e.g., if ring gear  334  is not mechanically connected to brake housing  342 ). The separator plates are mechanically connected to (e.g., splined with) brake housing  342 . Accordingly, when brake spring  346  applies a retarding force to brake pack  340  (e.g., according to a condition or operator input of machine  100 ), friction is increased between one or more of the friction discs and one or more of the separator plates of brake pack  340 . In this way, torque from the retarding force is applied to axle  324  (e.g., via carrier  336 ) and rotor shaft  312  (e.g., via planet gears  332  and sun gear  330 ). 
     As indicated above,  FIG. 3  is provided as an example. Other examples may differ from what is described with regard to  FIG. 3 . In some implementations, motor drive assembly  300  may include additional components, fewer components, different components, or differently arranged components than those shown in  FIG. 3 . 
       FIG. 4  is top view of an example dual path electric powertrain  400  within a frame  405  of machine  100  of  FIG. 1 . Frame  405  may correspond to frame  105  of  FIG. 1  and include an electric motor cavity  410  situated between frame mounts  412  on a left-side  414 - 1  and a right-side  414 - 2  of frame  405 . The dual path electric powertrain  400  includes motor drive assemblies  420  (shown as “ 420 - 1 ” and “ 420 - 2 ” and corresponding to motor drive assembly  300  of  FIG. 3 ). Accordingly, motor drive assemblies  420  may include and/or be fit within motor housings  430  (shown as “ 430 - 1 ” and “ 430 - 2 ” and corresponding to motor assembly  302 ), brake housings  440  (shown as “ 440 - 1 ” and “ 440 - 2 ” and corresponding to brake housing  342 ), and final drive housings  450  (shown as “ 450 - 1 ” and “ 450 - 2 ” and corresponding to final drive housing  320 ). 
     Frame  405  may be a frame of a relatively smaller machine (e.g., a smaller track-type tractor relative to a track-type tractor associated with frame  205  of  FIG. 2 ). Accordingly, dimensions and/or a shape of electric motor cavity  410  may be relatively smaller than dimensions and/or a shape of electric motor cavity  210  of  FIG. 2 . However, performance requirements of motor drive assemblies  420  may be different from the performance requirements of motor drive assemblies  220  because a machine associated with frame  405  is smaller than a machine associated with frame  205  of  FIG. 2 . 
     In  FIG. 4 , an example electric motor cavity  410  of frame  405  may be configured to fit motor housings  430  and brake housings  440  within electric motor cavity  410 . For example, as shown, electric motor cavity  410  may be formed from frame mounts  412  protruding a distance “D” from sides  415  of frame  405 . In some implementations (e.g., depending on dimensions of the motor drive assemblies  420  and/or machine that is to use the motor drive assemblies  420 ), motor housings  430  and brake housings  440  of motor drive assemblies  420  may fit within a frame that does not include frame mounts protruding from sides of the frame. 
     As indicated above,  FIG. 4  is provided as an example. Other examples may differ from what is described with regard to  FIG. 4 . 
     INDUSTRIAL APPLICABILITY 
     Developing and integrating a high-performance, long-life electric powertrain into a machine can be challenging due to size constraints of the machine (e.g., a size of a cavity to house the powertrain), inertia requirements of the powertrain, maximum weight constraints, cost constraints, and/or the like. Performance requirements (e.g., steering capability, drawbar pull and/or single track pull, propulsion capability, retarding capability, and/or the like) and/or durability standards previously required a dual path electric powertrain to be too large to fit within a desired compartment of a machine. For example, previous configurations of motor drive assemblies with motors that provide low enough inertia are too long to meet performance standards while still being able to fit coaxially between final drives of a track-type tractor. Accordingly, previous configurations required displacing and/or angling final drives relative to electric motors, which increases complexity, increases costs and/or quantities of components (e.g., to account for non-coaxially aligned components), and reduces durability (e.g., due to the increased number of working components and/or joints). 
     As described herein, a motor drive assembly for a coaxially aligned, dual path electric powertrain is configured to include a brake assembly and/or gear assembly configured between an electric motor and final drive that satisfies performance requirements for use in a track-type tractor while satisfying size constraints of the track-type tractor. Specifically, using a set of motor drive assemblies described herein, dual path electric powertrain  200  provides a compact modular design that provides a left electric motor and a right electric motor on a single axis, of a left final drive and right final drive, without increasing a track gauge of a machine (e.g., an existing track-type tractor of a particular size or having particular dimensions). The compact design may be achieved via a coaxially aligned dual path electric powertrain with shorter rotor shafts (relative to previous techniques), brake assemblies positioned externally from a powertrain compartment of a frame of the machine, and high-torque, switched reluctance motors with planetary gear reductions. In this way, at least a portion of a dual path electric powertrain, comprised of a pair of motor drive assemblies, as described herein, can fit into a same space as a mechanical transmission being replaced in a frame compartment of an existing machine (e.g., an existing track-type tractor that utilizes the mechanical transmission). 
     As described herein, to satisfy propulsion, steering, and/or braking requirements of a track-type tractor (e.g., a track-type tractor with an operating mass over 45,000 kilograms), a motor drive assembly can be configured to provide enough torque and steady state retarding power to facilitate effective braking capability and propulsion capability of a final drive, within a desired response window. Accordingly, pairs of motor drive assemblies, as described herein, can be coaxially aligned within a powertrain compartment of a machine, to form a dual path electric powertrain that provides enough torque, with low enough inertia, to satisfy minimum performance requirements of the machine and/or improve upon corresponding performance specifications of a similar machine that uses a mechanical powertrain. 
     As described herein, a configuration of a motor drive assembly (e.g., corresponding to motor drive assembly  300 ) that includes a brake assembly, as described herein, that can be utilized within a machine (e.g., a track-type tractor) to enable a machine operating mass to single track brake power ratio between 250 kg/kilowatt (kW) and 650 kg/kW (e.g., according to a desired responsiveness, a minimum duration of application, and/or the like without failing due to excessive temperature). Furthermore, a motor drive assembly, as described herein, may be included within a dual path electric powertrain of a track-type tractor to enable the track-type tractor to have a single track pull to machine operating weight ratio between 0.6 and 1.2, a machine operating mass to single track motor power ratio between 150 kg/kW and 300 kg/kW, a single track power to track gauge ratio between 90 and 225 kW/meter, and/or the like. Meanwhile, a set of motor drive assemblies, configured as described herein within a machine, may enable the machine to have a powertrain to machine inertia ratio between 1.5 and 3.5. Such performance specifications may be varied according to varying dimensions of the components of the motor drive assembly and/or varying positions of the components of the motor drive assembly relative to a frame of the machine. 
     Moreover, as described herein, a motor drive assembly may comprise modular components that are configured to enable access to individual assemblies (e.g., assemblies within the motor housings, brake housings, and/or final drive housings). This may improve serviceability of such components relative to current powertrain solutions. For example, serviceability of a brake assembly of the dual path electric powertrain is improved because the brake assembly of the dual path electric powertrain described herein can be positioned externally from an electric motor cavity or external side of a frame of a machine, thus reducing an amount of time to access the brake assembly and/or parts of the machine that are to be removed to access the brake assembly. 
     Furthermore, both motor drive assemblies of a dual path electric powertrain, configured as described herein, can be a same component and/or comprised of a same set of interchangeable components. Accordingly, the dual path electric powertrain, as described herein, can be configured from a limited quantity of interchangeable parts, thus reducing complexity and costs associated with designing and manufacturing components for different motor drive assemblies of the dual path electric powertrain.