You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13,004,955 filed Jan. 12, 2011, which was a divisional application of U.S. patent application Ser. No. 12/005,032 filed on Dec. 21, 2007, which is incorporated by reference herein for all it discloses. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention is directed to top drive systems; parts thereof; and methods of their use. 
         [0004]    2. Description of Related Art 
         [0005]    The prior art discloses a variety of top drive systems; for example, and not by way of limitation, the following U.S. patent application and U.S. patents present exemplary top drive systems and components thereof: U.S. Pat. Nos. 4,458,768; 4,589,503; 4,753,300; 4,800,968; 4,807,890; 4,813,493; 4,872,577; 4,878,546; 4,984,641; 5,433,279; 6,007,105; 6,276,450; 6,536,520; 6,679,333; 6,705,405; 6,913,096; 6,923,254; 7,186,686; and 7,270,189 all incorporated fully herein for all purposes. 
         [0006]    Certain typical prior top drive drilling systems have a derrick supporting a top drive which rotates tubulars, e.g., drill pipe. The top drive is supported from a traveling block beneath a crown block. A drawworks on a rig floor raises and lowers the top drive. The top drive moves on a guide track. 
         [0007]    Certain prior systems include a top drive with a gear system with a lower or second stage planetary carrier which rotates with respect to multiple (e.g. two) vertically spaced-apart bearings which are secured in place and which do not float radially (or axially). 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The following presents a simplified summary of the present disclosure in order to provide a basic understanding of some aspects of the invention. This summary is not an exhaustive overview of the disclosure, nor is it intended to identify key or critical elements of the subject matter disclosed here. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later. 
         [0009]    The present disclosure is generally directed to certain illustrative aspects of a top drive system that may be used during wellbore operations. In one exemplary embodiment, a system is disclosed that includes a gear system having a gear housing and a lower planetary carrier disposed in the gear housing, the lower planetary carrier being adapted to rotate relative to the gear housing. The illustrative system also includes, among other things, a top drive system that is operatively coupled to the gear system, the top drive system having a top drive shaft that is adapted to be driven by the gear system. Additionally, a single bearing is positioned between the gear housing and the lower planetary carrier, the single bearing being adapted to facilitate a rotation of the lower planetary carrier relative to the gear housing. Furthermore, a motor apparatus is operatively coupled to the gear system, the motor apparatus being adapted to drive the gear system by rotating the lower planetary carrier relative to the gear housing, wherein a rotational axis of the single bearing is adapted to move in a lateral translational direction with respect to the gear housing while the motor apparatus is rotating the lower planetary carrier and while the gear system is driving the top drive shaft. 
         [0010]    In another embodiment of the present disclosure, a system is disclosed that includes a gear system having a gear housing and a lower planetary carrier disposed in the gear housing, the lower planetary carrier being adapted to rotate relative to said gear housing. The system further includes, among other things, a single bearing positioned between the gear housing and the lower planetary carrier, the single bearing being adapted to facilitate a rotation of the lower planetary carrier relative to the gear housing, and a bearing cartridge that is adapted to maintain the single bearing in position between the gear housing and said lower planetary carrier. The bearing cartridge includes an outer part that is releasably secured to the gear housing and a radially movable inner part that is encompassed by the outer part, wherein the single bearing abuts the radially movable inner part. Furthermore, the system also includes a motor operatively coupled to the gear system, the motor being adapted to rotate the lower planetary carrier relative to the gear housing, wherein a rotational axis of the single bearing and a centerline axis of the radially movable inner part are adapted to move in respective lateral translational directions during the rotation of the lower planetary carrier relative to the gear housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The disclosure may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which: 
           [0012]      FIG. 1A  is a back view of a top drive system according to the present invention. 
           [0013]      FIG. 1B  is a side view of the top drive system of  FIG. 1A . 
           [0014]      FIG. 1C  is a front view of the top drive system of  FIG. 1A . 
           [0015]      FIG. 1D  is a cross-section view along line  1 D- 1 D of  FIG. 1C . 
           [0016]      FIG. 2A  is a perspective view of a top drive system according to the present invention with a motor/gear apparatus according to the present invention. 
           [0017]      FIG. 2B  is a partially exploded view of the top drive system and motor/gear apparatus shown in  FIG. 2A . 
           [0018]      FIG. 2C  is a cross-section view of the system of  FIG. 2A . 
           [0019]      FIG. 2D  is a side view of the system of  FIG. 2A . 
           [0020]      FIG. 2E  is a front view of the system of  FIG. 2A . 
           [0021]      FIG. 3  is a rear view of a top drive system of according to the present invention. 
           [0022]      FIG. 4A  is a perspective view of a gear apparatus for a top drive system according to the present invention. 
           [0023]      FIG. 4B  is a side view partially in cross-section of the apparatus of  FIG. 4A  (along line  4 B- 4 B of  FIG. 4C ). 
           [0024]      FIG. 4C  is a top of the apparatus of  FIG. 4A . 
           [0025]      FIG. 4D  is a bottom view of the apparatus of  FIG. 4A  with part in cross-section (along line  4 D- 4 D of  FIG. 4B ). 
           [0026]      FIG. 4E  is an enlargement of part of the apparatus of  FIG. 4B . 
       
    
    
       [0027]    While the subject matter disclosed herein is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION 
       [0028]    Various illustrative embodiments of the present subject matter are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
         [0029]      FIGS. 1A-1D  illustrate a top drive system  10  according to the present invention which has a plurality of components including: a gooseneck  11 , a bonnet  12 , brakes  13 , a motor  14 , a gear system  15 , a drive shaft  16 , a bearing system  17 , a swivel body  18 , a pipe handler lock assembly  19 , a link support  22 , a swivel ring  23  and a load (or landing) collar  29 . The components can be collectively suspended in a typical derrick from a typical traveling block for up and down movement in the derrick. 
         [0030]    During certain operations, the motor  14  within a housing  14   a  rotates the drive shaft  16  which, in turn, rotates a drill string and a drill bit to produce an earth bore. Fluid pumped into the top drive system through the gooseneck  11  passes through the drive shaft  16 , a drill string, and a drill bit and enters the bottom of an earth bore. 
         [0031]    In certain aspects, the motor housing  14   a  (e.g. made of sheet metal or aluminum) includes a series of tie rods  14   b  which are secured to a top member  14   c  and a bottom member  14   d  to strengthen the housing  14   a.  In certain particular aspects the housing  14   a  is made of metal such as aluminum or steel. In one particular aspect the motor  14  is a motor as disclosed in U.S. Pat. No. 7,188,686. In another particular aspect the motor  14  (as may be any motor herein) is a salient pole permanent magnet motor. 
         [0032]    The gear system  15  is located above a bearing retainer  21  which serves to maintain the drive shaft  16  in place (radially and axially) e.g. during drilling, and houses an upper race of a thrust bearing system  16   b.  As shown in  FIG. 1D , the bearing retainer is a separate item secured to and below the housing of the gear system  15 . As discussed in detail below, in one embodiment of the present invention, a bearing retainer is made integral with the gear system housing. A load flange  16   a  of the drive shaft  16  moves on bearings  16   c.    
         [0033]    An encoder/resolver  24  (see  FIG. 1D ) measures the position and speed of the motor  14  and provides a signal indicative of the position of the drive shaft  16 . With certain salient pole motors, the encoder/resolver  24  can be deleted since motor controls for salient pole permanent magnet motors indicate the position of the rotor of the motor and, therefore, the position of the drive shaft  16  (e.g., the position of the drive shaft during tubular connection make-up and break-out and during drilling). Certain typical salient pole motors (with embedded tangential or radial rotor magnets) have relatively higher inductance than non-salient motors and provide smoother starting from a standstill. 
         [0034]    The top drive system  10  has a motor control system  20  (shown schematically,  FIG. 1A ) which, in certain aspects, includes an output reactor  20   a  (also called an “inductor”) which insures efficient operation by increasing the inductance applied to the motor. This inductor is used with certain low inductance motors. In other aspects, by using a relatively high inductance motor, e.g. a relatively high inductance salient pole motor, the inductor  20   a  is eliminated since the high inductance motor applies a sufficient amount of inductance. 
         [0035]      FIG. 2A-2D  shows a top drive system  30  according to the present invention which, in some aspects, is like the system  10 ,  FIG. 1A  (and like numerals indicate like parts). A motor  14   m  (like any of the motors  14 ) is above a gear system  25  (instead of the gear system  15 ) has a housing  14   h.    
         [0036]    Parts of the housing  14   h  including sides  14   s,  top  14   t,  and bottom  14   v  following assembly are not connected together by tie rods (as are housing parts in the top drive of  FIG. 1A ). In one aspect the housing  14   h  is made of steel and is sufficiently strong so that a portion of it is threaded to threadedly connect the bonnet  12  thereto. A steel housing motor can be relatively larger than a motor with a weaker (e.g. aluminum) housing. This novel elimination of tie rods allows a motor of a greater diameter (larger size) to be used in a similar space. This relatively larger diameter means that the motor provides relatively greater horsepower with greater efficiency. 
         [0037]    A lower portion  48  of a gear housing  46  serves as a bearing retainer to retain bearing  44 .  FIGS. 2A-2D  are exploded views or views that show parts not assembled together. 
         [0038]    When assembled, the bearing  44  is within a bearing retainer  48 . The bearing retainer, a lower portion  48  of the housing  46  is releasably secured to the housing  46 , e.g. with bolts. 
         [0039]      FIG. 3  shows a top drive system  50  (partially exploded view) according to the present invention. A motor  60  has a brake system  54  and an output shaft  56 . The output shaft  56  is connected to a gear system  100 . The gear system  100  driven by the motor  60 , drives a main drive shaft  70 . Bearings  58  (thrust bearings) are retained in place by a bearing retainer  80  which is bolted to or integral with the gear system  100 . An attachment frame  90  (a “swivel body”) provides for the connection of a torque track for conducting torque from the system to the torque track. The swivel body  90  is, typically, suspended from a block in the derrick by bails. 
         [0040]      FIGS. 4A-4D  show the gear system  100  of the top drive system  50 . A housing  102  has a motor mounting surface  104  on which the motor is positioned. A part  107  is releasably secured to the housing with bolts  107   b.  Gear reducer system  110  within the housing  102  includes a gear reducer  111  and a bearing  116 . The gear reducer system  110  includes a first stage carrier  112 ; a second stage sun pinion  113 ; a second stage carrier  114 ; and a bearing cartridge  115 . The cartridge  115  with the bearing  117  is held in place by bolts  115 x. Removing the bolts  107   b  and the bolts  115 x permits removal of the cartridge  115  for bearing replacement, in one aspect, with a single bearing  117 . 
         [0041]    There are three first stage planetary gears  127  (see  FIG. 4C ). The gear system  100  has a bottom surface  130  (see  FIG. 4D ). A temperature gauge  134  can be inserted in a tapped thread portion  132 . A tip of the gauge sits in the oil flow path and dynamically measures the temperature of the oil flow. 
         [0042]    A lower portion  120  of part  107  of the housing  102  serves as a bearing retainer to retain in place the bearing  44  (see  FIG. 4E ). An inline flow meter  121  which measures oil flow to the housing has an oil inlet port  122 . Magnetic plugs  123  are positioned in holes  124  to attract and hold metal shavings and debris. An air breather  125  is in communication with the interior of the housing  120 . 
         [0043]    As shown in  FIGS. 4B and 4E , the cartridge  115  has a part  115   b  which is adjacent a part  115   a.  The part  115   a  includes an upper part  115   g  and a side  115   f.  The part  115   b  is encompassed within structure of the part  115   a  (upper part  115   g  and side  115   f ) and a top surface  107   a  of the part  107 . The part  115   a  rests on a top surface  107   b  of the part  107  and against a side  107   c  of the part  107 . In one aspect, the top surface  107   a  is lower than top surface  107   b.    
         [0044]    Due to the tolerances between the part  115   b  and the part  115   a  some slight movement is possible of the part  115   b  with respect to the part  115   a.  An interface between the parts  115   b  and  115   a  is sealed by one or more seals--two o-ring seals  115   c  are shown in corresponding recesses  115   d  in the part  115   b.  These seals are sized, configured, and positioned to accommodate the movement of the part  115   b  with respect to the part  115   a.    
         [0045]    The bearing  117  is held in place by a holder  114   c  bolted to the second stage carrier  114  by bolts  114   b  and rests partially on a ledge  115   e  of the part  115   b  and under a shoulder  114   d  of the carrier  114 . The bearing  117  can move radially (and/or axially) the extent that the part  115   b  can move radially (and/or axially), thus permitting the bearing  117  when it is movable radially to “float” horizontally. This inhibits interference in the horizontal plane between the bearing  117  and the bearing  44  (which can cause excessive bearing wear and premature failure). The bearing  117  does not float so much that the second stage carrier  114  moves too far axially, i.e., so far that splines on the periphery of the second stage carrier  114  would not properly mesh with corresponding splines on the main shaft of the motor. 
         [0046]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a top drive system for wellbore operations, the top drive system including: a main body; a motor apparatus; a main shaft extending from the main body, the main shaft having a top end and a bottom end, the main shaft having a main shaft flow bore therethrough from top to bottom through which drilling fluid is flowable; a quill connected to and around the main shaft; and, in one aspect, the quill is part of a gearbox of a gear system; a gear system interconnected with the quill, the gear system driven by the motor apparatus so that driving the gear system drives the quill and thereby drives the main shaft, the main shaft passing through the gear system; upper components connected to the main body above the top end of the main shaft. 
         [0047]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a top drive system for wellbore operations, the top drive system including a motor and gearing system including a motor housing, a motor within the motor housing, and the motor housing comprising a top and a bottom and a plurality of rods interconnected between the top and bottom to connect the top and the bottom together. 
         [0048]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a top drive system for wellbore operations, the top drive system including: a main body; a top drive shaft; a motor apparatus; a motor shaft extending from the motor; a gear system driven by the motor shaft, the gear system driven by the motor apparatus so that driving the gear system drives the top drive shaft, the gear system including a lower planetary carrier; the gear system including gear apparatus enclosed within a gear housing; a single bearing adjacent and in contact with the lower planetary carrier; a bearing cartridge connected to the gear housing; and the bearing cartridge abutting the single bearing and in contact with and holding the single bearing in position with respect to the lower planetary carrier. Such a system may have one or some, in any possible combination, of the following: the bearing cartridge including an outer part secured to the gear housing, and an inner part within the outer part, the inner part movable radially with respect to the outer part; the single bearing abuts the inner part and the inner part is movable radially with the single bearing; the single bearing maintains the lower planetary carrier in radial position; a shaft bearing around the top drive shaft, and a bearing retainer portion on a lower part of the gear housing for retaining the shaft bearing; wherein the inner part and the single bearing are movable to inhibit interference in the horizontal plane of the single bearing with the shaft bearing; wherein the motor apparatus is a salient pole permanent magnet motor apparatus; at least one seal on the inner part, the at least one seal projecting from the inner part and abutting the outer part, and the at least one seal accommodates movement of the inner part with respect to the outer part; there are two spaced-apart seal recesses on the inner part, and the at least one seal is two seals, one seal in each seal recess; wherein the bearing cartridge is releasably secured to a first part of the gear housing; and/or wherein the first part is releasably secured to the gear housing. 
         [0049]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a top drive system for wellbore operations, the top drive system including: a main body; a top drive shaft; a motor apparatus; a motor shaft extending from the motor; a gear system driven by the motor shaft, the gear system driven by the motor apparatus so that driving the gear system drives the top drive shaft, the gear system including a lower planetary carrier; the gear system including gear apparatus enclosed within a gear housing; a single bearing adjacent and in contact with the lower planetary carrier; a bearing cartridge connected to the gear housing; the bearing cartridge abutting the single bearing and in contact with and holding the single bearing in position with respect to the lower planetary carrier; the bearing cartridge including an outer part secured to the gear housing; an inner part within the outer part, the inner part movable radially with respect to the outer part; the single bearing abuts the inner part and the inner part is movable radially with the single bearing; wherein the single bearing maintains the lower planetary carrier in radial position; a shaft bearing around the top drive shaft; a bearing retainer portion on a lower part of the gear housing for retaining the shaft bearing; and wherein the inner part and the single bearing are movable to inhibit interference in the horizontal plane of the single bearing with the shaft bearing. 
         [0050]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a method for facilitating rotation of a lower planetary carrier of a gear system of a top drive system, the top drive system having a motor and gearing system including a motor housing, a motor within the motor housing, and the motor housing being a top and a bottom and a plurality of rods interconnected between the top and bottom to connect the top and the bottom together, the method including: rotating the lower planetary carrier with respect to the single bearing, and holding the single bearing in position with the bearing cartridge. Such a method may have one or some, in any possible combination, of the following: the bearing cartridge including an outer part secured to the gear housing, and an inner part within the outer part, the inner part movable radially with respect to the outer part, wherein the single bearing abuts the inner part and the inner part is movable radially with the single bearing, the method further including allowing the single bearing to move radially to an extent of possible radial movement of the inner part; wherein the single bearing maintains the lower planetary carrier in radial position, the method further including maintaining the lower planetary carrier in position with the single bearing; the top drive system having a shaft bearing around the top drive shaft, and a bearing retainer portion on a lower part of the gear housing for retaining the shaft bearing, the method further including retaining the shaft bearing in position with the bearing retainer portion; wherein the inner part and the single bearing are movable to inhibit interference in the horizontal plane of the single bearing with the shaft bearing, the method further including inhibiting interference in the horizontal plane between the single bearing and the shaft bearing; and/or the top drive system having at least one seal on the inner part, the at least one seal projecting from the inner part and abutting the outer part, the at least one seal accommodates movement of the inner part with respect to the outer part, the method further including with the at least one seal accommodating movement of the inner part with respect to the outer part. 
         [0051]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a method for inhibiting interference in the horizontal plane between a single bearing in a gear housing adjacent a lower planetary carrier of a gear system of a top drive system and a shaft bearing around a top drive shaft of the top drive system, the top drive system having a main body, a top drive shaft, a motor apparatus, a motor shaft extending from the motor, a gear system driven by the motor shaft, the gear system driven by the motor apparatus so that driving the gear system drives the top drive shaft, the gear system including a lower planetary carrier, the gear system including gear apparatus enclosed within a gear housing, a single bearing adjacent and in contact with the lower planetary carrier, a bearing cartridge connected to the gear housing, and the bearing cartridge abutting the single bearing and in contact with and holding the single bearing in position with respect to the lower planetary carrier, the method including allowing the single bearing to move radially with respect to the gear housing in a controlled manner. 
         [0052]    In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein and those covered by the appended claims are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited in any of the following claims is to be understood as referring to the step literally and/or to all equivalent elements or steps. The following claims are intended to cover the invention as broadly as legally possible in whatever form it may be utilized. The invention claimed herein is new and novel in accordance with 35 U.S.C. 102 and satisfies the conditions for patentability in section.  102 . The invention claimed herein is not obvious in accordance with 35 U.S.C. 103 and satisfies its conditions for patentability. This specification is in accordance with the requirements of 35 U.S.C. 112. The inventors may rely on the Doctrine of Equivalents to determine and assess the scope of their invention and of the claims that follow as they may pertain to apparatus not materially departing from, but outside of, the literal scope of the invention as set forth in the following claims. All patents and applications identified herein are incorporated fully herein for all purposes. 
         [0053]    Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.

Summary:
A system includes a gear system having a gear housing and a lower planetary carrier disposed in the gear housing, the lower planetary carrier being adapted to rotate relative to the gear housing. A top drive system is operatively coupled to the gear system, the top drive system having a top drive shaft that is adapted to be driven by the gear system. A single bearing that is adapted to facilitate rotation of the lower planetary carrier is positioned between the gear housing and the lower planetary carrier. A motor apparatus is operatively coupled to and adapted to drive the gear system by rotating the lower planetary carrier relative to the gear housing, wherein a rotational axis of the single bearing is adapted to move in a lateral translational direction with respect to the gear housing while the motor apparatus is rotating the lower planetary carrier.