Patent Publication Number: US-2018031102-A1

Title: Differential assembly for machine

Description:
TECHNICAL FIELD 
     The present disclosure relates to differential assemblies, and more particularly relates to a lockable differential assembly for a machine. 
     BACKGROUND 
     Typically, a differential assembly may be used in machines for driving wheels of the machine while also permitting a difference in rotational speed between the wheels. The differential assembly utilizes a gear system that permits two output shafts to rotate at different speeds. When the machine is operating on a surface where there is limited traction for different wheels, e.g., on a slippery road surface, one wheel may lose traction while the other wheel loses input torque. In order to avoid such a situation, differential action of the differential assembly needs to be locked. 
     Often, the differential assemblies are provided with a locking feature, referred to as a differential lock mechanism, to lock the differential action as and when required. The differential lock mechanism in a locked state thereof, allows both the output shafts to rotate at the same speed by transferring all available torque to both the output shafts. One example of differential locking mechanism includes a set of friction discs associated with a differential housing and the axle shafts. A piston applies force to engage the set of friction discs together. Therefore, when the differential is locked, power is transmitted through locked differential housing, gearing, and output shafts rather than through the differential gearing. However, there is no direct engagement of the output shaft even when the differential assembly is locked. Further, the size and configuration of the differential assembly may be critical when the differential assembly needs to fit within tight space constraints offered by the machine. 
     For reference, U.S. Pat. No. 4,344,335 relates to a power distributing device for four-wheel-drive vehicle including an input shaft, a first output shaft for transmitting power to rear wheels, a second output shaft for transmitting power to front wheels, a plane planetary gear set, a power train changing means and a synchronizing means. The plane planetary gear set includes a sun gear having a hollow shaft, a ring gear connected with the first output shaft, a planet carrier drivably connected with the input shaft, and planet gears carried by the planet carrier and engaged with the sun gear and the ring gear. The power train changing means includes a sliding sleeve and a sliding tube slidably mounted on the hollow shaft, engaged movably with the hollow shaft only in its axial direction, the sliding sleeve being selectively movable to engage either with a stationary portion of the device in a rear-wheel-drive condition or with the sun gear in a direct four-wheel-drive condition and a power distributing four-wheel-drive condition, the sliding tube being selectively movable to engage with the planet carrier in the direct four-wheel-drive condition. The synchronizing means is provided to inhibit nonsynchronous engagement of the sun gear with the stationary portion or the second output shaft. 
     SUMMARY OF THE DISCLOSURE 
     In one aspect of the present disclosure, a differential assembly for a drive train having a first axle shaft and a second axle shaft is provided. The differential assembly includes a differential gear set, a first pinion gear disposed on the first axle shaft, a second pinion gear disposed on the second axle shaft, each of the first pinion gear and the second pinion gear being in meshing engagement with the differential gear set, and a differential locking arrangement mounted on at least one of the first axle shaft and the second axle shaft. The differential locking arrangement is adapted to selectively lock the first axle shaft with the second axle shaft. 
     In another aspect of the present disclosure, a drive train for transmitting driving power from a power source to a first axle shaft and a second axle shaft is provided. The drive train includes an input shaft configured to receive the driving power from the power source, a drive gear drivably coupled to the input shaft, and a differential assembly for transmitting the driving power from the drive gear to the first axle shaft and the second axle shaft. The differential assembly includes a differential gear set connected to the drive gear, a first pinion gear disposed on the first axle shaft, a second pinion gear disposed on the second axle shaft, each of the first pinion gear and the second pinion gear being in meshing engagement with the differential gear set, and a differential locking arrangement mounted on at least one of the first axle shaft and the second axle shaft. The differential locking arrangement is adapted to selectively lock the first axle shaft with the second axle shaft. 
     In yet another aspect of the present disclosure, a method of transmitting driving power by a differential assembly, is provided. The method includes providing a connection between a first axle shaft and a first pinion gear via a first locking member of the differential assembly, providing a connection between a second axle shaft and a second pinion gear, wherein a second locking member of the differential assembly is connected to the second pinion gear. The method further includes engaging a first friction surface of the first locking member with a second friction surface of the second locking member for synchronizing rotational speeds of the first axle shaft and the second axle shaft. The method further includes engaging the first locking member with the second locking member by moving the first locking member with respect to the second locking member, and locking the first axle shaft with the second axle shaft. 
     Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a drive train of a vehicle; 
         FIG. 2  is a side sectional view of a differential assembly of the drive train, in accordance with an embodiment of the present disclosure; 
         FIG. 3  is a perspective exploded view of the differential assembly of the drive train, in accordance with an embodiment of the present disclosure; 
         FIG. 4  is a side sectional view of a differential assembly of the drive train, in accordance with another embodiment of the present disclosure 
         FIG. 5  is a perspective sectional view of the differential assembly of the drive train in a first position, in accordance with an embodiment of the present disclosure; 
         FIG. 6  is a perspective sectional view of the differential assembly of the drive train in a second position, in accordance with an embodiment of the present disclosure; 
         FIG. 7  is a perspective sectional view of the differential assembly of the drive train in a third position, in accordance with an embodiment of the present disclosure; and 
         FIG. 8  is flowchart of a method of transmitting driving power from a differential assembly, in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts. Moreover, references to various elements described herein are made collectively or individually when there may be more than one element of the same type. However, such references are merely exemplary in nature. It may be noted that any reference to elements in the singular is also to be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claims. 
     Referring to  FIG. 1 , a schematic view of a drive train  100  of an exemplary machine  102  is illustrated. The machine  102  may be embodied in the form of a backhoe loader, an excavator, a dozer, a wheel loader, a motor grader, an off-highway vehicle, an on-highway vehicle or other machines typically employed in applications, such as mining, forestry, waste management, construction, agriculture, transportation and the like. The present disclosure is generally relevant to any machine having the drive train  100 , as will become evident from the following description. 
     The machine  102  includes a frame  104  and a set of ground engaging members rotatably supported on the frame  104 . The frame  104  may also support the drive train  100 . The set of ground engaging members may be configured to provide mobility to the machine  102 . In the embodiment of  FIG. 1 , the set of ground engaging members are wheels. Further, the set of ground engaging members may include a pair of front ground engaging members  106 ,  108  disposed proximate to a front side of the machine  102 . The set of ground engaging members  106  may also include a pair of rear ground engaging members  110 ,  112  disposed proximate to a rear side of the machine  102 . Alternatively or additionally, the set of ground engaging members may include tracks (not illustrated). Although figures illustrate, the pair of front ground engaging members  106 ,  108  and the pair of rear ground engaging members  110 ,  112 , it may be recognized that the machine  102  may include any number of ground engaging members. 
     The machine  102  includes a power source  114  configured to generate driving power for various components including, but not limited to, the front and/or the rear set of ground engaging members  106 ,  108  and  110 ,  112 . The power source  114  may be an internal combustion engine. For example, the power source  114  may be embodied in the form of a diesel engine, a gasoline engine, a gaseous fuel-powered engine, or any other engine known in the art. It is also contemplated that the power source  114  may alternatively include a non-combustion source such as, for example, an electric motor, or be embodied in any other known non-combustion source of power. 
     The drive train  100  is configured to selectively transmit the driving power generated by the power source  114  to at least one of the pair of front ground engaging members  106 ,  108  and the pair of rear ground engaging members  110 ,  112 . In the illustrated embodiment of  FIG. 1 , the drive train  100  is configured to transmit the driving power only to the pair of rear ground engaging members  110 ,  112 . 
     The drive train  100  includes an input shaft  116  defining an axis A-A′. The input shaft  116  may be configured to receive the driving power from the power source  114  via a transmission system  118 . The transmission system  118 , also alternatively referred to as a gear box, may be operatively coupled between the power source  114  and a first end  120  of the input shaft  116 . The transmission system  118  may include various components such as, for example, gears, pinions, and the like to transmit the driving power from the power source  114  to the input shaft  116  at various speed-to-torque ratios. The input shaft  116  may rotate about the axis A-A′ upon receiving the driving power through the transmission system  118 . In various examples, the transmission system  118  may include a power-shift transmission, a continuously variable transmission, a hybrid transmission, or any other types of transmission systems known in the art. 
     The drive train  100  further includes a pair of axle shafts that are associated with the pair of rear ground engaging members  110 ,  112 . As shown in  FIG. 1 , a first axle shaft  122  and a second axle shaft  124  may be coupled to the rear ground engaging members  110 ,  112  respectively. Each of the first axle shaft  122  and the second axle shaft  124  may include first ends  126 ,  128  and second ends  130 ,  132  respectively. The first ends  126 ,  128  of the first axle shaft  122  and the second axle shaft  124  may be coupled to the rear ground engaging members  110 ,  112  respectively, for rotation therewith. 
     The drive train  100  also includes a differential assembly  200  disposed adjacent to a second end  119  of the input shaft  116 . In general, the differential assembly  200  may be configured to receive driving power from the input shaft  116  and provide a rotational output to the pair of the first axle shaft  122  and the second axle shaft  124  associated with the pair of rear ground engaging members  110 ,  112 . The differential assembly  200  may allow the pair of rear ground engaging members  110 ,  112  to rotate at different speeds and different torques relative to one another when required. As shown, the differential assembly  200  may be disposed in the proximity of the first ends  126 ,  128  of the first axle shaft  122  and the second axle shaft  124 , respectively. 
     The differential assembly  200  will be explained hereinafter in conjunction with the drive train  100  of  FIG. 1 . However, it may be noted that the differential assembly  200  disclosed herein may be configured for implementation in powertrains of various other configurations known in the art. For example, the differential assembly  200  may be configured to transmit the driving power to the pair of front ground engaging members  106 ,  108 , the pair of rear ground engaging members  110 ,  112 , a combination thereof, or as desired. 
       FIG. 2  depicts side sectional view a differential assembly  200  and  FIG. 3  depicts a perspective exploded view of the differential assembly  200 . Referring to  FIG. 2  and  FIG. 3  simultaneously, the differential assembly  200  includes a drive gear  202  for receiving a rotational input from the input shaft  116 . The drive gear  202  may be fixedly coupled to the input shaft  116  at the second end  119  thereof. Further, the input shaft  116 , as disclosed earlier herein, may receive the driving power from the power source  114  through the transmission system  118 . In the illustrated embodiment of  FIG. 2 , the drive gear  202  is a bevel gear. 
     The differential assembly  200  also includes a differential gear set  204 . In the illustrated embodiment, the differential gear set  204  includes a driven gear  206 , and differential gears  208  carried by the driven gear  206 . The driven gear  206  is configured to engage with the drive gear  202  so as to rotate in unison with the drive gear  202  during operation of the differential assembly  200 . In the illustrated embodiment, the driven gear  206  is embodied in the form of a ring gear. The driven gear  206  has an axis of rotation B-B′ about its center. The driven gear  206  may be disposed in mesh with the drive gear  202  such that the axis A-A″ of the input shaft  116  and the axis of rotation B-B′ of the driven gear  206  are disposed perpendicularly to each other. Further, the drive gear  202  may transmit the rotatory power to the driven gear  206  causing the driven gear  206  to rotate about the axis of rotation B-B′. 
     With continued reference to  FIGS. 2 and 3 , the differential assembly  200  may also include a first pinion gear  210 , a second pinion gear  212 , and a cover member  214 . The cover member  214  (also alternatively referred to as ‘differential case  214 ’ or ‘differential housing  214 ’) is rigidly coupled to the driven gear  206 , and houses the first pinion gear  210  and the second pinion gear  212 . In the illustrated embodiment of  FIG. 3 , the differential assembly  200  includes two cover members namely, a first cover member  214 A and a second cover member  214 B. However, in other embodiments, the differential assembly  200  may include a single-piece cover member or a cover member that is formed from more than two pieces. The specific number of pieces that form the cover member  214  of the present disclosure is merely exemplary in nature and hence, non-limiting of this disclosure. Persons ordinarily skilled in the art will appreciate that the cover member  214  disclosed herein may be made from any number of pieces without deviating from the spirit of the present disclosure. 
     The first cover member  214 A may be disposed adjacent to a first side of the driven gear  206 . Further, the first cover member  214 A may be configured to at least partially enclose the first side of the driven gear  206 . The second cover member  214 B may be disposed adjacent to a second side of the driven gear  206 . Further, the second cover member  214 B may be configured to at least partially enclose the second side of the driven gear  206 . 
     The first and second cover members  214 A,  214 B are rigidly coupled to the driven gear  206 . In the illustrated embodiment, each of the first and second cover members  214 A,  214 B may be coupled to the driven gear  206  with the help of fasteners  216  (shown in  FIG. 3 ). In an example as shown in  FIG. 3 , the fasteners  216  are embodied in the form of bolts. However, it may be contemplated to use other structures and methods known in the art for coupling each of the first and second cover members  214 A,  214 B to the driven gear  206 . 
     In an embodiment, the differential assembly  200  may operate so that a substantially equal amount of torque may be transmitted to each the first axle shaft  122  and the second axle shaft  124 . As such, the first axle shaft  122  and the second axle shaft  124  can rotate at different speeds relative to each other. 
     Each of the first pinion gear  210  and the second pinion gear  212  is housed within the cover member  214  and are configured to receive a rotational input from the driven gear  206 . The first pinion gear  210  may be disposed on a first side of the driven gear  206  and the second pinion gear  212  may be disposed on a second side, opposite to the first side, of the driven gear  206 . Moreover, the first pinion gear  210  and the second pinion gear  212  may be in a meshing engagement with each of the differential gears  208 . 
     Further, the first pinion gear  210  is coupled with the first axle shaft  122 , and the second pinion gear  212  is coupled with the second axle shaft  124 . As such, the first pinion gear  210  is coupled with the first axle shaft  122 , and the second pinion gear  212  is coupled with the second axle shaft  124  adjacent to the first ends  126 ,  128  of the respective axle shaft. The first pinion gear  210  and the second pinion gear  212  rotate with the corresponding axle shaft. 
     The differential assembly  200  further includes a differential locking arrangement  220 , positioned within the cover member  214 . The differential locking arrangement  220  is associated with at least one of the first axle shaft  122  and the second axle shaft  124 . In an embodiment illustrated in  FIGS. 2 and 3 , the differential locking arrangement  220  is mounted on the first axle shaft  122 . The differential locking arrangement  220  is adapted to selectively lock the first axle shaft  122  with the second axle shaft  124 . 
     The differential locking arrangement  220  includes a first locking member  222 , a lock actuator  224  and a sleeve member  226 . The first locking member  222  is engaged with the first axle shaft  122  and the first pinion gear  210 , while the lock actuator  224  is operably connected to the first locking member  222 . The lock actuator  224  may be adapted to engage the first locking member  222  with the second axle shaft  124  in order to lock the first axle shaft  122  with the second axle shaft  124 . It may herein be noted that in alternative embodiments, the first locking member  222  may be engaged with the second axle shaft  124  and the second pinion gear  212 , and in such an arrangement the lock actuator  224  may be adapted to engage the first locking member  222  with the first axle shaft  122  to lock the first axle shaft  122  with the second axle shaft  124 . When locked, the first axle shaft  122  and the second axle shaft  124  rotate at a same speed and therefore an equal amount of torque is transmitted to each of the pair of rear ground engaging members  110 ,  112 . 
     Specifically, as best illustrated in  FIG. 3 , the first locking member  222  has a hollow cylindrical profile having a first end portion  228 , a second end portion  229  opposite to the first end portion  228  and a set of splines formed on inner and outer surface of the first locking member  222 . The first end portion  228  of the first locking member  222  is associated with at least one return spring member, such as a return spring member  230 , positioned within the differential case  214 . In an embodiment of the present disclosure, the first end portion  228  of the first locking member  222  includes a circumferential tubular groove  232  to accommodate an end portion of the return spring member  230 . 
     An opposite end of the return spring member  230  may be engaged with at least one of the second axle shaft  124  and the second pinion gear  212 . Owing to such placement, the return spring member  230  may apply a force on the first locking member  222 . The return spring member  230  may be a coiled helical spring. The force applied by the return spring member  230  on the first locking member  222  is directionally opposite to the force applied by the lock actuator  224  on the first locking member  222 . Therefore, the force applied by the return spring member  230  on the first locking member  222  may assist in disengagement of the first locking member  222  from the second axle shaft  124 , when the force applied by the lock actuator  224  is removed. 
     The set of splines formed on the first locking member  222  include a first inner splined surface  234 , a second inner splined surface  236 , and an outer splined surface  238 . Each of the set of splines includes a set of elongated grooves. The first inner splined surface  234  of the set of splines is slidably engaged with the sleeve member  226 . The sleeve member  226  (also referred to as “sliding sleeve  226 ”) also includes an inner splined surface  240  slidably engaged with splines on an extension  242  on the first end  126  of the first axle shaft  122 . Owing to such engagement, the sleeve member  226  is adapted to slide along the axis B-B′ on the first axle shaft  122 . In order to selectively restrict such sliding movement of the sleeve member  226 , with respect to the first locking member  222 , a resilient mechanism  244  is located between the sleeve member  226  and the first locking member  222 . 
     The resilient mechanism  244  includes a set of balls, such as, a ball  246  and a set of spring members, such as, a spring member  248 . Each of the set of balls and spring members is positioned within a set of radial slots, such as, a radial slot  250  on the sleeve member  226 . In each of the radial slots, a spring member, such as, the spring member  248  is positioned and a ball, such as, the ball  246  is provided on top of the spring member  248 . The ball  246  is also engaged with a slot  252  on the first locking member  222 . The spring member  248  applies a pushing force on the ball  246  in contact with the slot  252  on the first locking member  222 , thereby engaging the sleeve member  226  with the first locking member  222 . Therefore, when a force along the axis B-B′ (a pushing force) is applied on the first locking member  222 , the first locking member  222  moves along with the sleeve member  226 . However, when a force applied on the first locking member  222  (along the axis B-B′) is greater than the force of the spring members, the set of balls get pushed and as a result, the sleeve member  226  gets disengaged from the first locking member  222 . In such a situation, the first locking member  222  may move relative to the sleeve member  226  along the first inner splined surface  234  on the first end portion  228  of the first locking member  222 . In an example of the present disclosure, the spring members may be coiled helical springs, and the balls may be metallic spheres. 
     The sleeve member  226  further includes a friction surface. The friction surface of the sleeve member  226  is adapted to frictionally engage with a friction surface of the second axle shaft  124 . In accordance with one embodiment of the present disclosure, the friction surface of the sleeve member  226  is embodied as a first conical surface  254 , and the friction surface of the second axle shaft  124  is embodied as a second conical surface  256 . As illustrated, the second conical surface  256  is disposed at the first end  128  of the second axle shaft  124 . An engagement of the first conical surface  254  with the second conical surface  256  frictionally connects the second axle shaft  124  with the sleeve member  226 , and thus with the first locking member  222 . Frictional engagement of the second axle shaft  124  with the first axle shaft  122  enables synchronization of rotational speeds of the first axle shaft  122  and the second axle shaft  124 . 
     In various examples, one or more of the first conical surface  254  and the second conical surface  256  may be provided with a friction lining made of a suitable and durable material, to increase friction coefficient of the first conical surface  254  and the second conical surface  256 . In various other examples, the first conical surface  254  may have any other shape and profile, e.g., a vertically flat profile and the second conical surface  256  may have a complimentary shape and profile, e.g., a vertically flat profile. 
     As shown in  FIG. 3 , a first set of engaging members  258  are disposed on the first locking member  222 . The first set of engaging members  258  are adapted to engage with the second axle shaft  124 . Specifically, the first set of engaging members  258  are adapted to engage with a second set of engaging members  260  of the second axle shaft  124 . In an embodiment, the first inner splined surface  234 , connecting the first locking member  222  with the sleeve member  226 , also aids in connecting the first locking member  222  with the second axle shaft  124 . Specifically, an end portion of the first inner splined surface  234 , defines the first set of engaging members  258  adapted to engage with a set of outwardly projecting tabs  262  located on the first end  128  of the second axle shaft  124 . As illustrated, a number of tabs on the set of outwardly projecting tabs  262  correspond to number of elongated grooves defining the first inner splined surface  234 . Further, each tab of the set of outwardly projecting tabs  262  may be shaped to engage with the first inner splined surface  234 . When the first set of engaging member  258  of the first locking member  222  are attached with the second set of engaging members  260 , relative rotation of the first axle shaft  122  with respect to the second axle shaft  124  is restricted, and thus the first axle shaft  122  is locked with the second axle shaft  124 . 
     The second inner splined surface  236  of the first locking member  222  is slidably engaged with splined surface  237  at the first end  126  of the first axle shaft  122 . The outer splined surface  238  of the first locking member  222  is engaged with a splined surface (not illustrated) on the first pinion gear  210 . In alternative embodiments of the present disclosure, the first locking member  222  may be coupled with the first end  126  of the first axle shaft  122  and the first pinion gear  210 , using any other means such that the first locking member  222  remains movable along the axis B-B′, with respect to the first axle shaft  122  and the first pinion gear  210 . The second end portion  229  of the first locking member  222  extends out of the differential case. A flange portion  264  is disposed at the second end portion  229  of the first locking member  222 . 
     The lock actuator  224  is carried by the differential case  214 , and is connected to the first locking member  222 . Specifically, the lock actuator  224  is connected to the flange portion  264  of the first locking member  222 . During operation of the differential assembly  200 , the lock actuator  224  can rotate independent of the first locking member  222 . The lock actuator  224 , when actuated, is adapted to apply pushing force on the first locking member  222  in order to move the first locking member  222  along the axis B-B.′ In various examples, the lock actuator  224  may be powered by a pneumatic actuating system, a hydraulic actuating system, mechanical, electromechanical, or magnetic actuating system. 
     Referring to  FIG. 4 , a differential assembly  400  in accordance with another embodiment of this disclosure is illustrated. Since the differential assembly  400  is generally reminiscent of the differential assembly  200  from  FIG. 2  and  FIG. 3 , components which are similar between the differential assembly  400  and the differential assembly  200  will be annotated by similar numbers increased by 200. Moreover, it should be noted that for purposes of brevity, re-capitulation in the explanation pertaining to components similar between the differential assembly  200  and the differential assembly  400  has been avoided herein. 
     In the illustrated embodiment of  FIG. 4 , the differential assembly  400  includes a differential locking arrangement  420  positioned within a cover member  414 . The differential locking arrangement  420  is associated with each of a first axle shaft  322  and a second axle shaft  324 . The differential locking arrangement  420  includes a first locking member  422 , and a second locking member  425 . The first locking member  422  is engaged with the first axle shaft  322  and a first pinion gear  410 . The second locking member  425  is engaged with at least one of the second axle shaft  324  and a second pinion gear  412 . Particularly, a first end  328  of the second axle shaft  324  may be connected to the second pinion gear  412  and the second pinion gear  412  may be connected to the second locking member  425 . The differential locking arrangement  420  is adapted to selectively engage the first locking member  422  with the second locking member  425  to lock the first axle shaft  322  with the second axle shaft  324 . 
     The second locking member  425  includes an end plate  426  facing the second axle shaft  324 , and a cylindrical peripheral member  428  extending from the end plate  426 . Further, the first locking member  422  has a cylindrical profile having an intermediate plate  431 , a first cylindrical member  432 , and a second cylindrical member  434 . Each of the first cylindrical member  432  and the second cylindrical member  434  extend from, and in opposite directions of, the intermediate plate  431 . Further, the first cylindrical member  432  faces the cylindrical peripheral member  428  to define a hollow cavity therebetween. A return spring member  430  is positioned within the first cylindrical member  432  and the cylindrical peripheral member  428 . Owing to such placement, the return spring member  430  applies a force on the first locking member  422 , and an opposite force on the second locking member  425 . 
     The second cylindrical member  434  of the first locking member  422  includes an inner splined surface  436  slidably engaged with the splined surface (not numbered) at a first end  326  of the first axle shaft  322 . An outer splined surface  438  on the second cylindrical member  434  of the first locking member  422  is engaged with splined surface (not numbered) on the first pinion gear  410 . In alternative embodiments of the present disclosure, the first lock member  422  may be coupled with the first end  326  of the first axle shaft  322 , and the first pinion gear  410  using any other means such that the first locking member  422  remains movable along the axis B-B′, with respect to the first axle shaft  322 , and the first pinion gear  410 . A flange portion  464  is disposed at a second end portion  429  of the first locking member  422 . 
     A lock actuator  424 , such as the lock actuator  224 , is carried by the differential case  414 , and is connected to the first locking member  422 . Specifically, the lock actuator  424  is connected to the flange portion  464  of the first locking member  422 . The lock actuator  424 , when actuated, is adapted to apply pushing force on the first locking member  422  in order to force the first locking member  422  along the axis B-B.′ In various examples, the lock actuator  424  may be a powered by a pneumatic actuating system, a hydraulic actuating system, mechanical, electromechanical, or magnetic actuating system. 
     The cylindrical peripheral member  428  of the second locking member  425  includes at least one channel  452  adapted to hold at least one synchronizing spring  454  connected to a friction surface  455 . The friction surface  455  faces a second friction surface  456  on the first cylindrical member  432  of the first locking member  422 . The friction surface  455  of the second locking member  425  is adapted to frictionally engage with the second friction surface  456  on the first cylindrical member  432  of the first locking member  422 . An engagement of the friction surface  455  with the second friction surface  456  frictionally connects the second axle shaft  324  with the first axle shaft  322 . Accordingly, frictional engagement of the second axle shaft  324  with the first axle shaft  322  enables synchronization of rotational speeds of the first axle shaft  322  and the second axle shaft  324 . 
     The first cylindrical member  432  of the first locking member  422  includes a first set of engaging members  458 . The first set of engaging members  458  in an embodiment of the present disclosure may be a set of splines. Further, the cylindrical peripheral member  428  of the second locking member  425  includes a second set of engaging members  451 . The first set of engaging members  458  of the first locking member  422  are adapted to engage with the second set of engaging members  451  of the second locking member  425  to lock the first axle shaft  322  with the second axle shaft  324 . 
     Referring now to  FIGS. 5, 6, and 7 , showing the differential locking arrangement  220  of the differential assembly  200  in three different positions.  FIG. 5  illustrates the differential locking arrangement  220  in a first position wherein the first axle shaft  122  is disengaged from the second axle shaft  124 . In the first position, there is no force applied by the lock actuator  224 , and owing to the return spring member  230  (shown in  FIGS. 2, and 3 ), the first axle shaft  122  is disengaged from the second axle shaft  124 . In such a position of the differential locking arrangement  220 , the first axle shaft  122  and the second axle shaft  124  may rotate at differential speeds, as the differential assembly  200  is unlocked.  FIG. 6  illustrates the differential locking arrangement  220  in a second position wherein the first axle shaft  122  is frictionally engaged with the second axle shaft  124 . 
     In the second position, force is applied by the lock actuator  224 , as a result the first locking member  222  slidably moves along the axis B-B′, with respect to the first axle shaft  122 . The sleeve member  226  remaining connected with the first locking member  222  may also move along the axis B-B′, with respect to the first axle shaft  122 . Further, the friction surface of the sleeve member  226 , such as the first conical surface  254  may come in contact with the second conical surface  256  at the first end  128  of the second axle shaft  124 , and accordingly the first axle shaft  122  is frictionally engaged with the second axle shaft  124 . The frictional engagement of the first axle shaft  122  with the second axle shaft  124  enables the synchronization of rotational speeds of the first axle shaft  122  and the second axle shaft  124 . 
     As per another embodiment of the present disclosure illustrated in  FIG. 4 , when the force is applied by the lock actuator  424 , the first locking member  422  slidably moves along the axis B-B′ with respect to the first axle shaft  322 . Further, the friction surface  455  of the second locking member  425  gets frictionally engage with the second friction surface  456  on the first cylindrical member  432  of the first locking member  422 . Further the force applied by the lock actuator  424 , presses the friction surface  455  towards the second friction surface  456 , pressing the synchronizing spring  454 . Such frictional engagement of the friction surface  455  of the second locking member  425  with the second friction surface  456  of the first locking member  422  frictionally connects the second axle shaft  324  with the first axle shaft  322 . Accordingly, frictional engagement of the second axle shaft  324  with the first axle shaft  322  enables synchronization of rotational speeds of the first axle shaft  322  and the second axle shaft  324 . 
       FIG. 7  illustrates the differential locking arrangement  220  in a third position wherein the first axle shaft  122  is locked with the second axle shaft  124 . In the third position, force is applied by the lock actuator  224 , as a result the first locking member  222  slidably moves further, along the axis B-B′, with respect to the first axle shaft  122 . The sleeve member  226  is displaced with respect to the first locking member  222 , as the force applied by the lock actuator  224  overcomes the force applied by the resilient mechanism  244  engaging the sleeve member  226 . Further, the first set of engaging members  258  of the first locking member  222  lock with the second set of engaging members  260  of the second axle shaft  124 , and accordingly the first axle shaft  122  is locked with the second axle shaft  124 . In such a position of the differential locking arrangement  220 , the first axle shaft  122  and the second axle shaft  124  may rotate at a same speed, as the differential assembly  200  is locked. 
     As per another embodiment of the present disclosure illustrated in  FIG. 4 , when the further force is applied by the lock actuator  424 , the first locking member  422  slidably moves further along the axis B-B′ with respect to the first axle shaft  322 . Because of the force applied by the lock actuator  424 , the return spring member  430  gets compressed, and the first set of engaging members  458  get locked with the second set of engaging members  451  and accordingly the first axle shaft  322  is locked with the second axle shaft  324 . In such a position of the differential locking arrangement  420 , the first axle shaft  322  and the second axle shaft  324  may rotate at a same speed, as the differential assembly  400  is locked. 
     Various additional components and features associated with the differential assembly  200 / 400  such as, seals, rings, bushings, spacers, bearings and the like have been omitted in the illustrations and explanation for the sake of simplicity and aiding clarity in understanding of the present disclosure. Therefore, such omission of the additional components and/or features must not be construed as being limiting of this present disclosure, rather the differential assembly  200 / 400  may be implemented with such additional components and/or features depending on specific requirements of an application. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure relates to a differential assembly for a machine. More specifically, the present disclosure relates to a lockable differential assembly for a machine. 
       FIG. 8  is a flowchart for a method  800  of transmitting driving power by a differential assembly, such as the differential assembly  200  or the differential assembly  400 , according to various embodiments of the present disclosure. For purposes of the present disclosure, embodiments disclosed in conjunction with  FIGS. 1 to 7  may be considered as being pursuant to the method  800 . Therefore, for the sake of brevity, the aspects of the present disclosure which are already explained in detail in the description of  FIG. 1 , through  FIG. 7  are not explained in detail with regard to the description of the method  800 . 
     At step  802 , the method includes providing a connection between a first axle shaft, such as the first axle shaft  122  or the first axle shaft  322 , and a first pinion gear, such as the first pinion gear  210  or the first pinion gear  410 . The connection between the first axle shaft and the first pinion gear may be provided via a first locking member, such as the first locking member  222  or the first locking member  422 . At step  804 , the method includes providing a connection between a second axle shaft, such as the second axle shaft  124  or the second axle shaft  324 , and a second pinion gear, such as the second pinion gear  212  or the second pinion gear  412 . The connection between the second axle shaft and the second pinion gear may be made by splines. The second pinion gear may be connected to a second locking member, such as the second locking member  425 . 
     At step  806 , the method includes engaging a friction surface  455  of the first locking member  422  with a second friction surface  456  of the second locking member  425  for synchronizing rotational speeds of the first axle shaft  322  and the second axle shaft  324 . In order to engage the friction surface  455  of the first locking member  422  with the second friction surface  456  of the second locking member  425 , a force is applied on the first locking member  422 , by a lock actuator, such as the lock actuator  424 , to move the first locking member  422  towards the second locking member  425 . Meanwhile, an opposing force is applied on the first locking member  422  and the second locking member  425 , by a return spring member  430 , to disengage the first locking member  422  from the second locking member  425  once the force applied by the lock actuator  424  is removed. 
     At step  808 , the method includes engaging the first locking member  422  with the second locking member  425  by moving the first locking member  422  with respect to the second locking member  425 . Further, at step  810 , the method includes locking the first axle shaft  322  with the second axle shaft  324  when the first locking member  422  is engaged with the second locking member  425 . 
     Embodiments of the present disclosure have applicability for implementation and use in reducing an overall weight and size of a differential assembly. Accordingly, embodiments of the present disclosure can help reduce an overall weight and size of a differential casing that is used to enclose components of a differential assembly therein. Previously known differential assemblies were conventionally produced using complex, bulky, and/or expensive components, for example a plurality of locking friction discs present on the differential case  214 , and one or more springs on the differential case  214 . However, with use of the differential locking assembly  220 / 420  (shown in  FIGS. 2 and 4  respectively) disclosed herein, a need of having plurality of locking frictions discs and one or more springs on the differential case  214  on the differential case  214  has been precluded, and accordingly the complexity and cost associated with the differential assembly has been reduced. 
     Moreover, the differential assemblies  200 / 400  of the present disclosure also allow for complete, slip proof, locking of the first axle shaft  122  with the second axle shaft  124 , when the first set of engaging members  258  of the first locking member  222  lock with the second set of engaging members  260  of the second axle shaft  124 . Further, the friction surface of the sleeve member  226 , such as the first conical surface  254  comes in contact with the second conical surface  256  at the first end  128  of the second axle shaft  124 , prior to engagement of the first locking member  222  with the second set of engaging members  260 . Because of such engagement of the friction surfaces, synchronization of the speed of the first axle shaft  122  with the second axle shaft  124  occurs. 
     Furthermore, as the components used in the differential assemblies  200 / 400  are simple and light-weight, such components may help manufacturers offset time and costs previously incurred with the use of complex, bulky, and/or expensive components when nesting differential gears inside a given differential assembly. Therefore, an overall size, weight, and production cost for the differential assemblies  200 / 400  of the present disclosure is minimized. Additionally, elimination of components such as springs, set of locking discs from outside the differential case, may provide space for fitment of other components of the drive train  100 . 
     While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.