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You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. patent application Ser. No. 09/601,643, filed on Oct. 20, 2000 now U.S. Pat. No. 6,695,559, which is herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention relates to an apparatus for delivering a tubular to a well centre. 
     During the construction of oil and gas wells a plurality of tubulars are transferred from a storage area to the well centre. Typically, each tubular is transferred to the V-slot adjacent the rig flow by a conveyor. The tubular is then lifted by an elevator and swung into position over the well centre ready for attachment to a string of tubulars extending down the well. 
     One of the difficulties associated with this process is that as the elevator moves the tubular, the tubular swings back and forth like a giant pendulum. This is potentially very hazardous, particularly when handling tubulars of large diameters. 
     An aim of at least preferred embodiments of the present invention is to reduce this problem. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention there is provided an apparatus for delivering a tubular to a well centre, which apparatus comprises means which, in use, inhibit swinging motion of the tubular whilst it is suspended from an elevator. 
     Preferably, said means comprises an arm which is pivotable between a first position and a second position. 
     Advantageously, said arm is provided with a stub axle which is provided with rollers for supporting said tubular. 
     Preferably, the apparatus further comprises a ramp which can be placed against a rig floor, and a tray which can support a tubular and be moved along said ramp. 
     The ramp may define an angle with the horizontal of between 30 degrees and 70 degrees, but it is normally intended to be used at angles of from 110 to 60 degrees. 
     In one embodiment, said arm is mounted on said ramp. 
     In another embodiment, said arm is mounted on said tray. 
     Alternatively, the arm may be mounted on the derrick. 
     Advantageously, said arm is rotatable about its axis to release said tubular therefrom, for example by an hydraulic motor. 
     Preferably, the apparatus includes an hydraulic motor to pivot said means. 
     According to another aspect of the present invention, there is provided an apparatus for delivering a tubular to a well centre, which apparatus comprises a ramp which can be placed against a rig floor, a tray for carrying said tubular and means which, in use, enables said tray to ascend or descend said ramp. 
     Preferably, said ramp further comprises a rack. 
     Advantageously, said means is a pinion mounted on said tray and engageable with said rack. 
     The means by which the tray moves along the ramp may be of any suitable means, but is preferably a rack and pinion. 
     Preferably, said means comprises two pinions, one mounted adjacent each end of said tray. 
     Advantageously, said tray further comprises a support wheel. 
     Preferably, said tray further comprises a pipe sledge mounted for longitudinal movement therein. 
     Advantageously, said tray further comprises a pipe pusher mounted such that, in use, said pipe pusher moves said tubular longitudinally within said tray. 
     According to another aspect of the present invention, there is provided an apparatus for delivering a tubular to a well centre, which apparatus comprises a tray for supporting said tubular, and means which, in use, can apply a force to said tubular to move it longitudinally with respect to said tray. 
     Preferably, said means comprises a piston and cylinder. 
     Advantageously, said apparatus further comprises a ramp which can be placed against a rig floor, and a tray which can be moved along said ramp. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the present invention reference will now be made, by way of example, to the accompanying drawings, in which: 
         FIG. 1  is a side view of an apparatus in accordance with the present invention about to deliver a tubular to the well centre of a drilling platform; 
         FIG. 2  is a side view, to an enlarged scale, of part of the apparatus shown in  FIG. 1  with the tubular mounted thereon; and 
         FIGS. 3 to 9  show successive stages in the operation of the apparatus. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For a better understanding of the present invention reference will now be made, by way of example, to the accompanying drawings, in which: 
       FIG. 1  is a side view of an apparatus in accordance with the present invention about to deliver a tubular to the well centre of a drilling platform; 
       FIG. 2  is a side view, to an enlarged scale, of part of the apparatus shown in  FIG. 1  with the tubular mounted thereon; and 
       FIGS. 3 to 9  show successive stages in the operation of the apparatus. 
     Referring to  FIG. 1  there is shown an apparatus which is generally identified by reference numeral  1 . 
     The apparatus  1  comprises a ramp  3  which extends upwardly to a rig floor  2  and a pipe tray  4 . The ramp  3  extends between the pipe tray  4  and a V-slot (not shown) in a derrick  5 . The derrick  5  is provided with an elevator  6  which is supported from a top drive slidably mounted on a track  7 . 
     A tubular  8  is shown within the derrick  5  having been screwed or otherwise attached to a string of tubulars (not shown) which extend down a wellbore (not shown) at the well centre. A tubular  9  is shown resting on the pipe tray  4  and is to be attached to the tubular  8  in the process of increasing the length of the string of tubulars within the wellbore. 
     Referring now to  FIG. 2  the ramp  3  further comprises a rack  10  which extends from the lower end of ramp  3  to the upper end of ramp  3 . 
     The pipe tray  4  further comprises two pinions  11 ,  12  which can be rotated by respective hydraulic motors (not shown) so that, in use, the pipe tray  4  can move either up or down the rack  10 . The pinion  11  is located at one end of the pipe tray  4  whilst the pinion  12  is located at the opposite end of pipe tray  4 . 
     A stabbing arm  13  is pivotally mounted at the end of pipe tray  4  and may be rotated by means of a swivel drive  14 . Swivel drive  14  can be actuated by a hydraulic motor (not shown) to move the stabbing arm  13  between a first position shown in  FIG. 2  and a second position shown in  FIG. 9  as more fully described hereafter. The stabbing arm  13  is provided with a stub axle  22  which carries rollers  19  to facilitate longitudinal movement of the tubular  9 . 
     A pipe sledge  15  resides within and at the rear end of the pipe tray  4 . The pipe sledge  15  has rollers  20  mounted at each end so that in use the pipe sledge  15  can move along the longitudinal axis of the pipe tray  4 . 
     A pipe pusher  16  which comprises a piston and cylinder is located substantially in abutment with the pipe sledge  15 . The pipe pusher  16  can be hydraulically activated so that the piston of the pipe pusher  16  will exert a force on the pipe sledge  15  to move the tubular  9  longitudinally within the pipe tray  4 . 
     Elastomeric sliding plates  18  are provided along the length of pipe tray  4  and allow the tubular  9  to rest therein. In use, the elastomeric sliding plates  18  are movable within the pipe tray  4  to help support the tubular  9 . 
     A support wheel  17  is located at the rear end of the pipe tray  4  which, in use, allows movement of the pipe tray  4  towards the V-slot in the derrick  5 . 
       FIGS. 3 to 9  show the apparatus in use. 
     Prior to using the apparatus  1  the tubular  9  is rolled onto the pipe tray  4  from a pipe deck (not shown). The pinion  11  is rotated. The teeth of the pinion  11  engage the rack  10  moving the pipe tray  4  toward the V-slot (not shown) in the derrick  5 , as shown in  FIG. 3 . The pinion  12  is rotated as it nears the ramp  3  so that upon engagement with the ramp  3  the pipe tray  4  continues to move toward the V-slot in the derrick  5 . 
     As shown in  FIGS. 4 and 5  the pinion  11  has left the ramp  3  but the pipe tray  4  continues to move toward the V-slot in the derrick  5  under the effect of the pinion  12 . The pinions  11 ,  12  are stopped when the pipe tray  4  has reached the position shown in  FIG. 5 . 
     The tubular  9  is pushed out of the pipe tray  4  by extending the piston in the pipe pusher  16 . The tubular  9  is pushed to a position where the elevator  6  can be easily attached to the tubular  9  as shown in  FIG. 6 . 
       FIG. 7  shows the elevator  6  having lifted the tubular  9  to a position where the lower end of tubular  9  is near the rollers  19  of the stabbing arm  13  and the upper end is substantially above the well centre. 
     Swivel drive  14  is now engaged to rotate the stabbing lever  13  clockwise between the first position, shown in  FIG. 7 , and the second position, shown in  FIG. 9 . Movement of the stabbing lever  14  brings the longitudinal axis of the tubular  9  from an inclined position with respect to the longitudinal axis of the borehole (not shown), to a position which is substantially in alignment with the axis of the borehole ( FIG. 9 ) (well center). The rollers  19  allow substantially vertical movement of the tubular  9 . Once this is completed the stabbing lever  14  is turned through 90° so that the stabbing lever  14  may be returned to its first position. The pipe tray  4  can then return to its initial position by reversal of the pinion drives  11 ,  12  to collect another tubular so that the process may be repeated. 
     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Summary:
An apparatus for delivering a tubular to a well center, which apparatus comprises means which, in use, inhibit swinging motion of the tubular while it is suspended from an elevator.