Patent Publication Number: US-2023145067-A1

Title: Drawworks apparatus and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. Patent Application Publication No. 2020/0386061, filed Aug. 25, 2020, which is a continuation application of U.S. Pat. No. 10,982,495, filed Sep. 8, 2016, which are incorporated by reference herein in their entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND 
     Hydrocarbon drilling systems utilize drilling fluid or mud for drilling a wellbore in a subterranean earthen formation. In some applications, drilling systems include a drawworks for controlling the displacement of a drillstring of the drilling system into and out of the wellbore. Particularly, the drawworks is configured to control the displacement of a drilling line of the drilling system that helps support the drillstring via a travelling block coupled to the drilling line, where the drillstring is suspended from the travelling block via a hook coupled to the travelling block. The drilling line is reeled over a stationary crown block forming a “block and tackle” arrangement to provide mechanical advantage in manipulating the drillstring. In some applications, the drawworks includes a drum about which the drilling line is spooled, where the drum is powered by one or more electric motors that supply the drum with torque via a gearbox coupled between the drum and one or more electric motors. In some applications, the drum includes one or more disk brakes or clutches to provide braking and positional control of the drum. In certain applications, the gearbox of the drawworks is coupled to the drum by a rotational shaft that extends into the drum, where torque is transferred between the gearbox and drum via the rotational shaft. 
     SUMMARY 
     An embodiment of a drum for a drawworks assembly comprises a drum body comprising a first end, a second end, and a longitudinal axis, a first planar engagement surface disposed at the first end of the drum body, and a second planar engagement surface disposed at the second end of the drum body, wherein both the first and second engagement surfaces comprise a plurality of circumferentially spaced first apertures, the first apertures configured to receive a plurality of fasteners configured to releasably couple the drum to the drawworks assembly, wherein the first and second engagement surfaces comprise a plurality of circumferentially spaced second apertures, the second apertures configured to receive a plurality of pin assemblies configured to transmit torque between the drum and a driveshaft of the drawworks assembly. In some embodiments, the first and second engagement surfaces comprise annular engagement surfaces. In some embodiments, the first planar engagement surface of the drum is configured to releasably couple with a planar engagement surface of a coupling assembly of the drawworks assembly. In certain embodiments, the plurality of fasteners are configured to extend through a plurality of circumferentially spaced first apertures disposed in the engagement surface of the coupling assembly and threadably engage the first apertures of the first engagement surface to releasably couple the coupling assembly with the drum body. In certain embodiments, the plurality of pin assemblies are configured to extend through both a plurality of circumferentially spaced second apertures disposed in the engagement surface of the coupling assembly and the plurality of second apertures of the first engagement surface to provide for the transmission of torque between the coupling assembly and the drum body. In some embodiments, the second planar engagement surface of the drum is configured to releasably couple with a planar engagement surface of a cradle assembly of the drawworks assembly. In some embodiments, the plurality of fasteners are configured to extend through a plurality of circumferentially spaced first apertures disposed in the engagement surface of the cradle assembly and threadably engage the first apertures of the second engagement surface to releasably couple the cradle assembly with the drum body. In certain embodiments, the plurality of second apertures each comprise a diameter this greater than a diameter of each of the plurality of first apertures. 
     An embodiment of a drawworks assembly comprises a drum comprising a first end, a second end, and a longitudinal axis, a coupling assembly configured to transmit torque to the drum, and a cradle assembly configured to support the drum, wherein the coupling assembly is releasably coupled to the drum at a first planar engagement interface disposed at the first end of the drum, wherein the cradle assembly is releasably coupled to the drum at a second planar engagement interface disposed at the second end of the drum. In some embodiments, the first engagement interface and the second engagement interface are both disposed substantially orthogonal to the longitudinal axis of the drum. In some embodiments, the first end of the drum comprises a first planar engagement surface comprising a plurality of circumferentially spaced first apertures and a plurality of circumferentially spaced second apertures. In certain embodiments, the drawworks assembly further comprises a plurality of circumferentially spaced fasteners extending through a hub of the coupling assembly, wherein each fastener threadably engages one of the plurality of first apertures to releasably couple the coupling assembly with the drum. In certain embodiments, the drawworks assembly further comprises a plurality of circumferentially spaced pin assemblies extending through a hub of the coupling assembly, wherein each pin assembly is disposed in one of the plurality of second apertures to provide for the transmission of torque between the coupling assembly and the drum. In some embodiments, each pin assembly comprises an outer sleeve comprising a first end, a second end, and a bore extending between the first and second ends, a pin disposed in the bore of the outer sleeve, wherein the pin comprises a an outer surface having a diameter that varies across the longitudinal length of the pin, and a threaded fastener extending into an aperture of the pin, wherein rotation of the threaded fastener is configured to longitudinally displace the pin through the bore of the outer sleeve and adjust a diameter of an outer surface of the sleeve. In some embodiments, a diameter of each pin assembly is greater than a diameter of each fastener. In certain embodiments, the drum comprises a bore extending between the first and second ends of the drum, and neither the coupling assembly nor the cradle assembly extend into the bore of the drum. 
     An embodiment of a method of manipulating a drum of a drawworks assembly comprises removing a first plurality of fasteners releasably coupling a drum with a coupling assembly, removing a second plurality of fasteners releasably coupling the drum with a cradle assembly, and lifting the drum vertically from the drawworks assembly. In some embodiments, as the drum is lifted vertically from the drawworks assembly, a longitudinal axis of the drum remains substantially parallel with a longitudinal axis of the drawworks assembly. In some embodiments, as the drum is lifted vertically from the drawworks assembly, the coupling assembly and the cradle assembly are disposed stationary on a frame of the drawworks assembly. In certain embodiments, the method further comprises vertically lowering the drum until a longitudinal axis of the drum is aligned with a longitudinal axis of the drawworks assembly, inserting the first plurality of fasteners into a plurality of circumferentially spaced apertures disposed in a first planar engagement surface of the drum to releasably couple the coupling assembly with the drum, and inserting the second plurality of fasteners into a plurality of circumferentially spaced apertures disposed in a second planar engagement surface of the drum to releasably couple the cradle assembly with the drum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a detailed description of exemplary embodiments, reference will now be made to the accompanying drawings in which: 
         FIG.  1    is a schematic view of an embodiment of a drilling system in accordance with principles disclosed herein; 
         FIG.  2    is a first perspective view of an embodiment of a drawworks assembly of the drilling system shown in  FIG.  1    in accordance with principles disclosed herein; 
         FIG.  3    is a second perspective view of the drawworks assembly shown in  FIG.  2   ; 
         FIG.  4    is a side cross-sectional view of the drawworks assembly of  FIG.  2    shown in a first position; 
         FIG.  5    is a side view of an embodiment of a drum of the drawworks assembly shown in  FIG.  2    in accordance with principles disclosed herein; 
         FIG.  6    is a cross-sectional view alone line  6 - 6  of  FIG.  5    of the drum shown in  FIG.  5   ; 
         FIG.  7    is a perspective view of an embodiment of a spherical coupling assembly of the drawworks assembly shown in  FIG.  2    in accordance with principles disclosed herein; 
         FIG.  8    is a side view of the spherical coupling assembly shown in  FIG.  7   ; 
         FIG.  9    is a cross-sectional view along line  9 - 9  of  FIG.  8    of the spherical coupling assembly shown in  FIG.  7   ; 
         FIG.  10    is an exploded, perspective view of the spherical coupling assembly shown in  FIG.  7   ; 
         FIG.  11    is a zoomed-in, cross-sectional view along line  9 - 9  of  FIG.  8    of an embodiment of a fastener assembly of the spherical coupling assembly shown in  FIG.  7    in accordance with principles disclosed herein; 
         FIG.  12    is a side view of an embodiment of a cradle assembly of the drawworks assembly shown in  FIG.  2    in accordance with principles disclosed herein; 
         FIG.  13    is a cross-sectional view alone line  13 - 13  of  FIG.  12    of the cradle assembly shown in  FIG.  12   ; 
         FIG.  14    is an exploded, perspective view of a hub of the cradle assembly shown in  FIG.  12   ; 
         FIG.  15    is a cross-sectional view alone line  14 - 14  of  FIG.  12    of an embodiment of a fastener assembly of the cradle assembly shown in  FIG.  12   ; and 
         FIG.  16    is a side cross-sectional view of the drawworks assembly of  FIG.  2    shown in a second position. 
     
    
    
     DETAILED DESCRIPTION 
     In the drawings and description that follow, like parts are typically marked throughout the specification and drawings with the same reference numerals. The drawing figures are not necessarily to scale. Certain features of the disclosed embodiments may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. The present disclosure is susceptible to embodiments of different forms. Specific embodiments are described in detail and are shown in the drawings, with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce desired results. 
     Unless otherwise specified, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Any use of any form of the terms “connect”, “engage”, “couple”, “attach”, or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described. The various characteristics mentioned above, as well as other features and characteristics described in more detail below, will be readily apparent to those skilled in the art upon reading the following detailed description of the embodiments, and by referring to the accompanying drawings. 
     Referring now to  FIG.  1   , a schematic diagram of an embodiment of a drilling system  10  in accordance with the principles described herein is shown. Drilling system  10  includes a drilling assembly  90  for drilling a borehole  26 . In addition, drilling system  10  includes a derrick  11  having a floor  12 , which supports a rotary table  14  that is rotated by a prime mover such as an electric motor (not shown) at a desired rotational speed and controlled by a motor controller (not shown). In other embodiments, the rotary table (e.g., rotary table  14 ) may be augmented or replaced by a top drive suspended in the derrick (e.g., derrick  11 ) and connected to the drillstring (e.g., drillstring  20 ). 
     Drilling assembly  90  comprises a drillstring  20  including a drill pipe  22  extending downward from the rotary table  14  through a pressure control device  15  into the borehole  26 . The pressure control device  15  is commonly hydraulically powered and may contain sensors for detecting certain operating parameters and controlling the actuation of the pressure control device  15 . A drill bit  50 , attached to the lower end of drillstring  20 , disintegrates the earthen formations when it is rotated with weight-on-bit (WOB) to drill the borehole  26 . Drillstring  20  is coupled to a drawworks assembly  100  via a kelly joint  21 , swivel  28 , and drilling line  29  through a travelling block  30 . In this arrangement, drawworks  100  may be actuated to reel in or out drilling line  29 , which acts to raise or lower travelling block  30 . During drilling operations, drawworks  100  is operated to control the WOB, which impacts the rate-of-penetration of drill bit  50  through the formation. In this embodiment, drill bit  50  may be rotated from the surface by drillstring  20  via rotary table  14  and/or a top drive, rotated by downhole mud motor  55  disposed in drilling assembly  90 , or combinations thereof (e.g., rotated by both rotary table  14  via drillstring  20  and mud motor  55 , rotated by a top drive and the mud motor  55 , etc.). For example, rotation via downhole motor  55  may be employed to supplement the rotational power of rotary table  14 , if required, and/or to effect changes in the drilling process. In either case, the rate-of-penetration (ROP) of the drill bit  50  into the borehole  26  for a given formation and a drilling assembly largely depends upon the weight-on-bit and the drill bit rotational speed. Further, while in this embodiment drawworks  100  is used in drilling system  10 , in other embodiments drawworks  100  may be used in other drilling systems, including offshore drilling systems. 
     During drilling operations a suitable drilling fluid  31  is pumped under pressure from a mud tank  32  through the drillstring  20  by a mud pump  34 . Drilling fluid  31  passes from the mud pump  34  into the drillstring  20  via a fluid line  38 , and the kelly joint  21 . Drilling fluid  31  is discharged at the borehole bottom through nozzles in face of drill bit  50 , circulates to the surface through an annular space  27  radially positioned between drillstring  20  and the sidewall of borehole  26 , and then returns to mud tank  32  via a solids control system  36  and a return line  35 . Solids control system  36  may include any suitable solids control equipment known in the art including, without limitation, shale shakers, centrifuges, and automated chemical additive systems. Control system  36  may include sensors and automated controls for monitoring and controlling, respectively, various operating parameters such as centrifuge rpm. It should be appreciated that much of the surface equipment for handling the drilling fluid is application specific and may vary on a case-by-case basis. 
     Referring to  FIGS.  2 - 4   , views of an embodiment of drawworks assembly  100  are shown. In this embodiment, drawworks  100  generally includes a central or longitudinal axis  105 , a skid or support frame  102 , a transmission or gearbox  110 , a drum or drum body  120 , a coupling or spherical coupling assembly  200 , and a cradle assembly  300 . Support frame  102  is disposed on floor  12  of derrick  11  (shown in  FIG.  1   ) and is configured to physically support the components of drawworks  100  and to transmit operational loads of drawworks  100  to the substructure of floor  12 . Drawworks  100  additionally includes one or more motors or power sources (not shown) configured to generate and provide rotational torque to a driveshaft  112  of gearbox  110 . In certain embodiments, the one or more motors comprise electric motors, while in other embodiments the one or more motors may comprise diesel engines. Gearbox  110  is configured to receive rotational torque from the one or more motors and provide a desired rotational speed and/or mechanical advantage to driveshaft  112  via one or more gears disposed therein. 
     Spherical coupling assembly  200  is coupled between gearbox  110  and drum  120  and is generally configured to transmit rotational torque received from gearbox  110  (via driveshaft  112 ) to drum  120 . While drawworks assembly  100  is shown as including spherical coupling assembly  200 , in other embodiments, drawworks  100  may comprise other components configured to transmit torque between drum  120  and gearbox  110 . In this embodiment, spherical coupling assembly  200  is configured to transmit rotational torque between driveshaft  112  of gearbox  110  and drum  120  even when a longitudinal axis of driveshaft  112  and a longitudinal axis of drum  120  are angularly misaligned. In this manner, drum  120  may be rotated about its longitudinal axis via torque transmitted from gearbox  110  and spherical coupling assembly  200 . Cradle  300  is coupled between drum  120  and support frame  102  and is configured to physically support drum  120 . As will be described further herein, cradle  300  includes a bearing assembly configured to provide a rotational coupling between drum  120  and cradle  300  to allow for relative rotation between drum  120  and stationary components of cradle  300 . In this arrangement, spherical coupling assembly  200  and cradle  300  provide for physical support of drum  120  at each longitudinal end of drum  120 . 
     In the embodiment shown in  FIGS.  2 - 4   , drawworks assembly  100  additionally includes a pair of disk brakes  114 , with one disk brake  114  coupled to each longitudinal end of drum  120  such that drum  120  and brakes  114  rotate in concert. In the embodiment shown, each disk brake  114  comprises a pair of arcuate sections extending approximately 180°; however, in other embodiments each disk brake  114  may comprise a single annular member. Drawworks  100  further includes a pair of caliper assemblies  116 , where each caliber assembly  116  is positioned proximal a corresponding disk brake  114  to provide for selectable frictional engagement between a brake pad (not shown) of the caliber assembly  116  and the corresponding disk brake  114  to control the rotation of drum  120  about its longitudinal axis. Although in the embodiment shown in  FIGS.  2 - 4    drawworks  100  includes disk brakes  114  and associated caliper assemblies  116 , in other embodiments drawworks  100  may include other mechanisms for providing braking of drum  120  or otherwise controlling the rotation or rotational position of drum  120 . 
     Referring to  FIGS.  5  and  6   , an embodiment of drum  120  of drawworks  100  is shown. In the embodiment shown in  FIGS.  5  and  6   , drum  120  is generally cylindrical and includes a central or longitudinal axis  125 , a first longitudinal end  120   a , a second longitudinal end  120   b  axially spaced from first end  120   a , a central bore or passage  122  extending between ends  120   a ,  120   b , and defined by a generally cylindrical inner surface  124 , and an outer surface  126  extending between longitudinal ends  120   a  and  120   b . When drum  120  is coupled with spherical coupling assembly  200  and cradle assembly  300  (shown in  FIGS.  2 - 4   ), the longitudinal axis  125  is disposed substantially coaxial with longitudinal axis  105  of drawworks assembly  100 . The outer surface  126  of drum  120  includes a pair of radially outwards extending flanges  128  disposed proximal longitudinal ends  120   a  and  120   b , and a groove  130  extending between flanges  128 . In certain embodiments, groove  130  comprises a Lebus groove configured to prevent snagging of drilling line  29  during spooling and/or unspooling of line  29 . 
     In this embodiment, each longitudinal end  120   a  of drum  120  includes a radially inner engagement surface  132  and a radially outer engagement surface  134  radially spaced from inner engagement surface  132 . In some embodiments, radially inner engagement surface  132  comprises a planar and/or inner engagement surface  132 . Inner engagement surface  132  of drum  120  extends radially outwards from inner surface  124  while outer engagement surface  134  extends radially inwards from outer surface  126 . Inner engagement surface  132  disposed at first end  120   a  is configured to matingly engage and releasably couple with a corresponding engagement surface of spherical coupling assembly  200  while the inner engagement surface  132  disposed at second end  120   b  is configured to matingly engage and releasably couple with a corresponding engagement surface of cradle assembly  300 , as will be discussed further herein. In this embodiment, inner engagement surfaces  132  each comprise annular planar surfaces disposed orthogonal longitudinal axis  125  of drum  120 . In other words, a diameter of each planar inner engagement surface  132  orthogonally intersects longitudinal axis  125 . Similarly, outer engagement surfaces  134  each comprise annular planar surfaces disposed orthogonal longitudinal axis  125 . 
     In this embodiment, each inner engagement surface  132  of drum  120  includes a first plurality of circumferentially spaced threaded apertures  138  and a first plurality of circumferentially spaced unthreaded apertures  140  extending therein, where threaded apertures  138  and unthreaded apertures  140  are disposed along a common circumference. Additionally, each threaded aperture  138  and unthreaded aperture  140  extends along an axis disposed substantially parallel with longitudinal axis  125  and orthogonal inner engagement surface  132 . As will be discussed further herein, each threaded fastener  138  is configured to receive a corresponding threaded fastener while each unthreaded aperture  140  is configured to receive a corresponding unthreaded fastener or shear pin assembly. As shown particularly in  FIG.  5   , each unthreaded aperture  140  is disposed circumferentially between a pair of flanking threaded apertures  138 . As shown particularly in  FIG.  6   , each unthreaded aperture  140  includes a first or outer bore  142  and a second or inner bore  144  where outer bore  142  extends axially into inner engagement surface  132  from a longitudinal end of drum  120  (either first end  120   a  or second end  120   b ) and inner bore  144  extends further axially into engagement surface  132  from a terminal end of outer bore  142 . In this configuration, outer bore  142  comprises a diameter that is greater than a diameter of inner bore  144 . Additionally, in this embodiment the diameter of the outer bore  142  of each unthreaded aperture  140  is greater than a diameter of each threaded aperture  138 . 
     Each outer engagement surface  134  of drum  120  also includes a second plurality of circumferentially spaced threaded apertures  138  and a second plurality of unthreaded apertures  140  extending axially therein, with the second plurality of threaded apertures  138  and the second plurality of unthreaded apertures  140  disposed along a common circumference. In addition, each unthreaded aperture  140  of the second plurality is flanked circumferentially by a pair of threaded apertures  138 , similar to the arrangement of apertures  138  and  140  on inner engagement surfaces  132 . Although in the embodiment shown in  FIGS.  5  and  6    includes second pluralities of threaded apertures  138  and unthreaded apertures  140  extending in each outer engagement surface  134 , in other embodiments, outer engagement surface  134  may not include apertures  138  and  140 . In this embodiment, each outer engagement surface  134  is configured to matingly engage and releasably couple with a corresponding disk brake  114 . In certain embodiments, drum  120  may not include outer engagement surface  134 , such as in embodiments of drawworks  100  that do not include disk brakes  114 . 
     Referring to  FIGS.  7 - 10   , an embodiment of spherical coupling assembly  200  is shown. As described above, spherical coupling assembly  200  is generally configured to transmit torque from gearbox  110  to drum  120  via driveshaft  112 . In the embodiment shown in  FIGS.  7 - 9   , spherical coupling assembly  200  generally includes an annular outer hub or body  202 , an annular spherical coupler  240 , a first or inner annular connecting flange  260 , and a second or outer annular connecting flange  280 . Spherical coupler  240  is configured to receive torque from driveshaft  112  and transmit the received torque to hub  202  via a splined connection interface disposed radially therebetween while connecting flanges  260  and  280  are configured to restrict relative axial movement and thereby secure spherical coupling  240  to hub  202 . 
     In this embodiment, hub  202  has a central or longitudinal axis  205 , a first or longitudinally inner end  202   a , a second or longitudinally outer end  202   b , a central bore  204  extending between ends  202   a ,  202   b , and defined by an inner surface  206 , and an outer surface  208  extending between ends  202   a  and  202   b . As shown particularly in  FIG.  9   , the inner surface  206  of hub  202  includes a plurality of circumferentially spaced splines  210  extending radially inwards therefrom for engaging a corresponding plurality of splines of spherical coupler  240 . Inner surface  206  additionally includes a radially extending annular flange  212  for matingly engaging and releasably coupling with inner connecting flange  260 . The outer surface  208  of hub  202  includes a radially outwards extending flange  214  disposed at inner longitudinal end  202   a . As shown particularly in  FIGS.  9  and  10   , the longitudinally inner end  202   a  of hub  202  comprises an annular engagement surface  216  configured to matingly engage and releasably couple with the inner engagement surface  132  of the first end  120   a  of drum  120 . In this embodiment, engagement surface  216  comprises a planar surface disposed orthogonal longitudinal axis  205  of hub  202 . In other words, a diameter of planar engagement surface  216  orthogonally intersects longitudinal axis  205  of hub  202 . 
     As shown particularly in  FIG.  10   , engagement surface  216  of hub  202  includes a plurality of circumferentially spaced first apertures  218  and a plurality of circumferentially spaced second apertures  220 , where first apertures  218  and second apertures  220  are disposed along a common circumference. Particularly, the circumference upon which apertures  218  and  220  are disposed comprises a diameter that is equal in size to a diameter of the circumference on which apertures  138  and  140  of drum  120  are disposed. Additionally, each first aperture  218  and second aperture  220  extends along an axis disposed substantially parallel with longitudinal axis  205  and orthogonal engagement surface  216 . Further, each second aperture  220  is disposed circumferentially between a pair of flanking first apertures  218 . In this arrangement, when the longitudinal axis  205  of hub  202  and the longitudinal axis  125  of drum  120  are aligned, and apertures  218  and  220  of hub  202  are circumferentially aligned with apertures  138  and  140  of drum  120 , apertures  218  and  220  of hub  202  are aligned with apertures  138  and  140  of drum  120 , allowing for the passage of a fastener or pin through corresponding pairs of apertures  138  and  218 , and apertures  140  and  220 . 
     Moreover, in this embodiment each first aperture  218  of hub  202  comprises a diameter that is similar in size to the diameter of each threaded aperture  138  of drum  120 , and each second aperture  220  of hub  202  comprises a diameter that is similar in size to the diameter of each unthreaded aperture  140 . However, in other embodiments the diameter of each first aperture  218  may vary from the diameter of each threaded aperture  138 , and the diameter of each second aperture  220  may vary from the diameter of each unthreaded aperture  220 . As will be discussed further herein, first apertures  218  are configured to receive threaded fasteners  222  while second apertures  220  are configured to release pin assemblies  400 , where fasteners  222  and pin assemblies  400  are configured to releasably couple spherical coupling assembly  200  with drum  120 . In certain embodiments, a washer is used in conjunction with each threaded fastener to distribute loads from the fastener  222 . 
     In the embodiment shown in  FIGS.  7 - 10   , spherical coupler  240  generally includes a bore  242  defined by a generally cylindrical inner surface  244 , and a curved or hemispherical outer surface  246 . The inner surface  244  of coupler  240  includes a groove or slot for receiving a corresponding spline of driveshaft  112  to restrict relative rotation between driveshaft  112  and coupler  240  and thereby allow for the transmission of torque between gearbox  110  and spherical coupling assembly  200 . The curved outer surface  246  of spherical coupler  240  includes a plurality of circumferentially spaced splines  248  extending radially outwards therefrom, where splines  248  are configured to matingly engage the circumferentially spaced splines  210  of hub  202  to thereby provide for the transmission of torque between spherical coupler  240  and hub  202 . Inner connecting flange  260  includes a curved or partially spherical inner surface  262  and a radially extending engagement interface  264  configured to matingly engage and releasably couple with flange  212  of hub  202  via a plurality of circumferentially spaced fasteners. Similarly, outer connecting flange  280  includes a curved or partially spherical inner surface  282  and a radially extending engagement interface  284  configured to matingly engage and releasably couple with the longitudinally outer end  202   b  of hub  202  via a plurality of circumferentially spaced fasteners. In this arrangement, connecting flanges  260  and  280  secure spherical connector  240  within hub  202  while allowing for angular misalignment between the longitudinal axis  205  of hub  202  and a longitudinal axis of spherical coupler  240 . In this manner, hub  202  may be rotated and torque may be transmitted from coupler  240  to hub  202  even when the longitudinal axis  205  of hub  202  and the longitudinal axis of coupler  240  are angularly misaligned. 
     Referring to  FIGS.  12 - 15   , an embodiment of cradle assembly  300  is shown. In this embodiment, cradle assembly  300  generally includes a support frame  302 , a housing  310 , a bearing assembly  320 , and an annular hub  360 . Support frame  302  is configured to assist in physically supporting drum  120  and is coupled to support frame  102  (shown in  FIGS.  2 - 4   ) of drawworks assembly  100 . Housing  310  is supported on frame  302  and houses and supports bearing assembly  320 , where bearing assembly  320  is configured to provide for relative rotation between hub  360  and the housing  310  and support frame  302 . Particularly, bearing assembly  320  is disposed within a chamber  312  of housing  310  and generally includes a plurality of roller bearings  322  disposed radially between a radially outer annular bearing race  324  and a radially inner annular bearing race  326 , where relative rotation is permitted between bearing races  324  and  326  via roller bearings  322 . In this embodiment, roller bearings  322  are inclined or angled relative a longitudinal axis  345  of hub  340  to provide support both radial and axial or thrust loads applied against hub  340  of cradle assembly  300 . 
     In the embodiment shown in  FIGS.  12 - 15   , hub  340  of cradle assembly  300  is configured to releasably couple with the second longitudinal end  120   b  of drum  120  and generally includes a first or longitudinally inner end  340   a , a second or longitudinally outer end  340   b , a central bore  342  extending between ends  340   a ,  340   b  and defined by an inner surface  346 , and an outer surface  348  extending between ends  340   a  and  340   b . The outer surface  346  of hub  340  couples with the radially inner bearing race  326  of bearing assembly  320  proximal longitudinal outer end  340   b  to couple hub  340  with bearing assembly  320 . Outer surface  346  includes a radially outwards extending flange  348  disposed proximal inner longitudinal end  340   a . As shown particularly in  FIG.  13   , the longitudinally inner end  340   a  of hub  340  comprises an annular engagement surface  350  configured to matingly engage and releasably couple with the inner engagement surface  132  of the second end  120   b  of drum  120 . In this embodiment, engagement surface  350  comprises a planar surface disposed orthogonal longitudinal axis  345  of hub  340 . In other words, a diameter of planar engagement surface  350  orthogonally intersects longitudinal axis  345  of hub  340 . 
     As shown particularly in  FIGS.  13  and  14   , engagement surface  350  of hub  340  includes a plurality of circumferentially spaced first apertures  352  and a plurality of circumferentially spaced second apertures  354 , where first apertures  352  and second apertures  354  are disposed along a common circumference. Particularly, the circumference upon which apertures  352  and  354  are disposed comprises a diameter that is equal in size to a diameter of the circumference on which apertures  138  and  140  of drum  120  are disposed. Additionally, each first aperture  352  and second aperture  354  extends along an axis disposed substantially parallel with longitudinal axis  345  and orthogonal engagement surface  350 . Additionally, each second aperture  354  is disposed circumferentially between a pair of flanking first apertures  352 . In this arrangement, when the longitudinal axis  345  of hub  340  and the longitudinal axis  125  of drum  120  are aligned and apertures  352  and  354  of hub  340  are circumferentially aligned with apertures  138  and  140  of drum  120 , apertures  352  and  354  of hub  340  are axially aligned with apertures  138  and  140  disposed at the second end  120   b  of drum  120 , allowing for the passage of a fastener or pin through corresponding pairs of apertures  138  and  352 , and apertures  140  and  354 . 
     Moreover, in this embodiment each first aperture  352  of hub  340  comprises a diameter that is similar in size to the diameter of each threaded aperture  138 , and each second aperture  354  of hub  340  comprises a diameter that is similar in size to the diameter of each unthreaded aperture  140 . However, in other embodiments the diameter of each first aperture  352  may vary from the diameter of each threaded aperture  138 , and the diameter of each second aperture  354  may vary from the diameter of each unthreaded aperture  354 . Further, first apertures  352  are configured to receive threaded fasteners  222  (along with a washer in this embodiment) while second apertures  354  are configured to release pin assemblies  400  to releasably couple hub  340  and cradle assembly  300  with drum  120 . 
     Referring to  FIGS.  8 ,  11 ,  12  and  15   , cross-sectional views of an embodiment of pin assembly  400  are shown. Particularly,  FIG.  11    illustrates a pin assembly  400  disposed in a second aperture  220  of the hub  202  of spherical coupling assembly  200  while  FIG.  15    illustrates a pin assembly  400  disposed in a second aperture  354  of the hub  340  of cradle assembly  300 . In the embodiment shown in  FIGS.  11  and  15   , each pin assembly  400  generally includes an outer sleeve  402 , a generally cylindrical pin  420  at least partially disposed in the sleeve  402 , and a threaded fastener  440  at least partially disposed in an aperture of the pin  420 . As shown particularly in  FIGS.  8  and  12   , an arcuate cover plate  450  extends over a longitudinally outer end of each pin assembly  400 , where each cover plate  450  is secured into position via a pair of threaded fasteners  222  circumferentially flanking the pin assembly  400 . In some embodiments, cover plates  450  may be used to prevent debris or particulates from entering the second apertures  220  of hub  202  and/or the second apertures  354  of hub  340 . In some embodiments, a seal may be disposed longitudinally between cover plate  450  and the radially outer end of the corresponding pin assembly  400  to assist in preventing debris from entering apertures  220  and/or  354 . Outer sleeve  402  of pin assembly  400  has a first or longitudinally inner end  402   a , a second or longitudinally outer end  402   b , a central bore  404  extending between ends  402   a ,  402   b  and defined by a generally cylindrical inner surface  406 , and an outer surface  408  extending between ends  402   a  and  420   b . In some embodiment, sleeve  402  comprises a c-ring including a slot extending between ends  402   a  and  402   b  to allow for the radial expansion and/or contraction of bore  404 . 
     In this embodiment, pin  420  of pin assembly  400  generally includes a first or longitudinally inner end  420   a , a second or longitudinally outer end  420   b , and a generally cylindrical outer surface  422  extending between ends  420   a  and  420   b . In addition, pin  420  includes an aperture  424  extending longitudinally into second end  420   b , where aperture  424  includes a threaded inner surface. Fastener  440  includes a threaded outer surface  442  for threadably connecting with the threaded inner surface of the aperture  424  of pin  420 . In this arrangement, rotation of fastener  440  (e.g., via the application of a tool, etc.) results in longitudinal displacement of pin  420  through the bore  404  of sleeve  402 . Further, bore  404  of sleeve  402  increases in diameter moving from inner end  402   a  to outer end  402   b  while the outer surface  422  of pin  420  decreases in diameter moving from inner end  420   a  to outer end  420   b . In other words, the outer surface  422  of pin  420  comprises a frustoconical surface that varies in diameter along the longitudinal length of pin  420 . 
     In this configuration, longitudinal displacement of pin  420  in a first direction towards the outer end  402   b  of sleeve  402  results in an increase in the diameter of bore  404  and the outer surface  408  of sleeve  402  as the larger diameter section of the outer surface  422  of pin  420  disposed proximal inner end  420   a  enters the bore  404  of sleeve  402 , forcing sleeve  402  to expand radially outwards. Conversely, longitudinal displacement of pin  420  in a second direction towards the inner end  402   a  of sleeve  402  results in a decrease in the diameter of bore  404  and the outer surface  408  of sleeve  402  as the larger diameter section of outer surface  422  is displaced from the bore  404  of sleeve  402 . In this manner, the diameter of the outer surface  408  of sleeve  402  may be adjusted via the longitudinal displacement of pin  420  within bore  404 , which is controlled by rotation of fastener  440 . 
     Referring to  FIGS.  2 ,  3 ,  5 ,  6 ,  9 ,  11 ,  13 ,  15 , and  16   , when drawworks assembly  100  is disposed in an assembled position shown in  FIGS.  2  and  3   , a pin assembly  400  is received in each unthreaded aperture  140  and a threaded fastener  222  is received in each threaded aperture  138  to releasably couple drum  120  to both spherical coupling assembly  200  and cradle assembly  300 . In this position, torque may be transmitted from gearbox  110  to drum  120  via spherical coupling assembly  200 . In particular, torque applied to spherical coupling assembly  200  is transmitted to drum  120  via the plurality of threaded fasteners  222  and pin assemblies  400  extending between each corresponding pair of first apertures  218  and threaded apertures  138  for threaded fasteners  222 , and second apertures  220  and unthreaded apertures  140  for pin assemblies  400 . Particularly, fasteners  222  and pin assemblies  400  transmit torque to drum  120  via a shear force applied to each fastener  222  and assembly  400 . 
     In this embodiment, pin assemblies  400  comprise a larger diameter and cross-sectional area than fasteners  222 , increasing the amount of shear force that may be applied to each assembly  400  and thereby allowing each pin assembly  400  to transmit a greater amount of torque to drum  120  from gearbox  110 . Moreover, each threaded fastener  222 , when it is threadably connected with drum  120 , is placed under tension, reducing the amount of shear force that may be applied to each fastener  222  before failure. Given that pin assemblies  400  are not threadably coupled to drum  120 , assemblies  400  are not placed under a tension load, freeing them to absorb more shear load when applying torque to drum  120 . Therefore, the inclusion of pin assemblies  400  reduces the overall number of fasteners and/or pins required to releasably couple drum  120  with spherical coupling assembly  200  and cradle assembly  300  and transmit torque between gearbox  110  and drum  120 . The reduced number of fasteners provided for by pin assemblies  400  allows for the diameter of each inner engagement surface  132  to be reduced, thereby reducing the necessary diameter or size of drum  120 . Moreover, the reduction of fasteners provided by pin assemblies  400  reduces the amount of time required to couple or decouple drum  120  from drawworks assembly  100 . 
     In the arrangement described above, a pair of annular, lateral or orthogonal coupling interfaces  146  (shown in  FIG.  4   ) are formed between drum  120  and the spherical coupling assembly  200  and cradle assembly  300 , where drum  120  is releasably coupled to spherical coupling assembly  200  at a first interface  146  and drum  120  is releasably coupled to cradle assembly  300  at a second interface  146 . In certain embodiments, coupling interfaces  146  comprise planar and/or annular engagement interfaces  146 . A first annular coupling interface  146  is formed between the inner engagement surface  132  of drum  120  at first end  120   a  and the engagement surface  216  of the hub  202  of spherical coupling assembly  200 , and a first annular coupling interface  146  is formed between the engagement surface  132  of drum  120  at second end  120   b  and the engagement surface  350  of the hub  340  of cradle assembly  300 . Each annular interface  146  is disposed orthogonal the longitudinal axis  125  of drum  120 . In other words, the diameter of each annular interface  146  intersects longitudinal axis  125  at a substantially normal or 90° angle. 
     Given that drum  120  is releasably coupled to assemblies  200  and  300  of drawworks  100  at orthogonal coupling interfaces  146  instead of via a stub-shaft or other member extending into the bore  122  of drum  120 , drum  120  may be removed from drawworks  100  without removing or otherwise displacing spherical coupling assembly  200  and cradle assembly  300 . As shown particularly in  FIG.  16   , to remove drum  120  from drawworks  100  the threaded fasteners  222  and pin assemblies  400  are removed from each aperture  138  and  140 , respectively, of drum  120 , allowing for drum  120  to be displaced vertically (as indicated by arrow  160  in  FIG.  16   ) with longitudinal axis  125  remaining parallel with the longitudinal axis  105  (i.e., parallel the ground and/or rig floor  12  shown in  FIG.  1   ) or of drawworks assembly  100 . During operation of drawworks  100 , drum  120  may be removed to refurbish groove  130  or for other reasons. The ability to remove drum  120  via vertically lifting drum  120  as shown in  FIG.  16    reduces the amount of time required for removing drum  120  from drawworks  100  by eliminating the need for decoupling spherical coupling assembly  200  and cradle assembly  300  from frame  102  such that assemblies  200  and  300  may be displaced or manipulated to provide sufficient room for removing drum  120 . Moreover, as discussed above, the use of pin assemblies  400  decreases the total number of fasteners and/or pins required for coupling drum  120  to drawworks  100 , further decreasing the time required for removing drum  120  from drawworks  100 . 
     Following removal of drum  120  from drawworks  100 , drum  120  may be reinstalled (or a new drum  120  may be installed in its place) by vertically lowering drum  120  with longitudinal axis  125  disposed parallel with longitudinal axis  105  of drawworks  100  until longitudinal axis  125  of drum  120  is disposed substantially coaxial with longitudinal axis  105  of drawworks assembly  100 . Once drum  120  is substantially coaxially aligned with drawworks  100 , drum  120  is rotated until threaded apertures  138  are circumferentially aligned with first apertures  218  and  352  of hub  202  and hub  340 , respectively, and unthreaded apertures  140  are circumferentially aligned with second apertures  220  and  354  of hubs  202  and  340 , respectively. 
     Following the circumferential alignment of drum  120  with hubs  202  and  340 , pin assemblies  400  are inserted into their corresponding unthreaded apertures  140  of drum  120 . In this arrangement, pin assemblies  400  disposed at the first end  120   a  of drum  120  extend across interface  146  and are received within both unthreaded apertures  140  of drum  120  and second apertures  220  of hub  202 , restricting relative rotation between hub  202  and drum  120 . Similarly, pin assemblies  400  disposed at the second end  120   b  of drum  120  extend across interface  146  and are received within both unthreaded apertures  140  of drum  120  and second apertures  354  of hub  340 , restricting relative rotation between hub  340  and drum  120 . Once pin assemblies  400  are received within unthreaded apertures  140 , the fastener  440  of each assembly  400  may be rotated to longitudinally displace the corresponding pin  420  to adjust the diameter of sleeve  402 . For instance, in some embodiments pin  420  of each assembly  400  may be retracted into the bore  404  of sleeve  402  to expand the diameter of sleeve  402  and pin assembly  400  to reduce or eliminate any “play” or clearance between the outer surface  408  of sleeve  402  and the inner surface of the unthreaded aperture  140 . Once pin assemblies  400  are received within unthreaded apertures  140  of drum  120 , threaded fasteners  222  (including cover plates  450 ) are threadably coupled to their corresponding threaded apertures  138  of drum  120 , thereby releasably coupling drum  120  to spherical coupling assembly  200  and cradle assembly  300 . 
     Thus, a method is provided for manipulating a drum (e.g., drum  120 ) of a drawworks assembly (e.g., drawworks assembly  120 ) that comprises removing a first plurality of fasteners (e.g., fasteners  222 ), releasably coupling a drum with a coupling assembly (e.g., spherical coupling assembly  200 ), removing a second plurality of fasteners (e.g., fasteners  222 ), releasably coupling the drum with a cradle assembly (e.g., cradle assembly  300 ), and lifting the drum vertically from the drawworks assembly. In certain embodiments, the method comprises vertically lowering the drum until a longitudinal axis of the drum is aligned with a longitudinal axis of the drawworks assembly, inserting the first plurality of fasteners into a plurality of circumferentially spaced apertures disposed in a first annular engagement surface of the drum to releasably couple the coupling assembly with the drum; and inserting the second plurality of fasteners into a plurality of circumferentially spaced apertures disposed in a second annular engagement surface of the drum to releasably couple the cradle assembly with the drum. 
     The above discussion is meant to be illustrative of the principles and various embodiments of the present disclosure. While certain embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the disclosure. The embodiments described herein are exemplary only, and are not limiting. Accordingly, the scope of protection is not limited by the description set out above, but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims.