A tong for use at a wellbore includes a tong body; at least one door pivotally coupled to the tong body and movable between an open position and a closed position; a carrier ring rotatable relative to the tong body; and a brake plate coupled to the carrier ring. The tong also includes a brake band configured to move with the at least one door between the open and closed positions, and a braking member for moving the brake band into contact with the brake plate to stop rotation of the carrier ring.

BACKGROUND

Field

Embodiments described herein generally relate to a tong for use at a wellbore. In particular, embodiments described herein relate to a braking assembly for a tong. In particular still, embodiments described herein relate to a brake band for a braking assembly for a tong.

Description of the Related Art

Wellbore tongs are well known in the art for making and breaking threaded connections between tubulars as strings are assembled or disassembled for use in a wellbore. Typically, a back-up or lower tong holds a tubular extending from the wellbore while an upper tong grasps and then rotates a new tubular into or out of the string. In most cases, the upper tong includes a mechanism to grasp the tubular and then, in a separate step, rotates the tubular to perform threading or unthreading. During the grasping step, one rotating portion of the assembly must be held in place while the gripping assembly operates. Thereafter, both portions are rotated as a unit during the threading operation. There is a need for an improved braking assembly for preventing or stopping a rotatable component of the tong.

SUMMARY

In one embodiment, a tong for use at a wellbore includes a tong body; at least one door pivotally coupled to the tong body and movable between an open position and a closed position; a carrier ring rotatable relative to the tong body; and a brake plate coupled to the carrier ring. The tong also includes a brake band configured to move with the at least one door between the open and closed positions, and a braking member for moving the brake band into contact with the brake plate to stop rotation of the carrier ring.

In another embodiment, a method of operating a tong includes opening a door of the tong, wherein the tong includes a tong body; the door pivotally coupled to the tong body; a carrier ring rotatable relative to the tong body; a brake plate coupled to the carrier ring; and a brake band having a door band portion attached to the door. The method also includes moving the door band portion of the brake band with the door as the door opens; closing the door; moving the brake band into contact with the carrier ring, thereby preventing rotation of the carrier ring; and rotating a gear ring relative to the carrier ring.

In another embodiment, a method of operating a tong includes opening a door of the tong. The tong may include a tong body; the door pivotally coupled to the tong body; a carrier ring rotatable relative to the tong body; a brake plate coupled to the carrier ring; and a brake band having a door band portion attached to the door. The method also includes moving the door band portion of the brake band with the door as the door opens; closing the door; rotating the carrier ring; and moving the brake band into contact with the brake plate, thereby stopping rotation of the carrier ring.

In one embodiment, a tong for use at a wellbore includes a tong body; at least one door pivotally coupled to the tong body and movable between an open position and a closed position; a gripping assembly rotatable relative to the tong body; and a brake plate coupled to the gripping assembly. The tong may also include a brake band configured to move with the at least one door between the open and closed positions; and a braking member for moving the brake band into contact with the brake plate to stop rotation of the gripping assembly.

DETAILED DESCRIPTION

FIG. 1is a perspective view of a wellbore tong. The tong has two functions: it grasps a tubular (not shown) using a gripping assembly generally shown as110and thereafter, it rotates the tubular relative to a tubular therebelow in order to make or break a threaded connection therebetween. A door120, shown in a closed position, permits the tubular to be inserted into the gripping assembly110of the tong100. A hydraulic motor assembly generally shown as130rotates a gear ring (not visible) that is responsible for rotation of the tubular when a connection is made. Separately, a “cage” or brake plate140is rotatable independent of the gear ring. In the embodiment shown, the gripping assembly110is associated with the rotatable brake plate140and rotates therewith. Separately, inwardly facing ramps (not visible) are formed on an inner surface of the gear ring. To grip a tubular with the tong100, it is necessary to rotationally fix the brake plate140with its gripping assembly110while rotating the gear ring in order to urge the ramps of the gear ring under a plurality of wheels associated with the gripping assembly110. The action of the wheels and ramps acts to close gripping members112,115around the tubular. With the tubular gripped, both the gear ring and the brake plate140rotate together to make (or break) a connection.

FIG. 2is a perspective view of a portion of the tong100including the rotatable brake plate140, the gripping assembly110rotatable therewith and a separately rotatable gear ring150. The gear ring includes teeth formed on a perimeter thereof for engagement with corresponding teeth associated with the motor assembly130(FIG. 1). Also shown inFIG. 2is a braking assembly for the brake plate in order to stop its rotation during the gripping portion of the operation. The breaking assembly, as will be described in additional detail herein, includes a brake band160that can be tightened thereby providing friction between the band160and the brake plate140. The tightening takes place at each end of the band with piston-actuated braking members165a,165b.

FIG. 3is a top view of the assembly ofFIG. 2showing gripping members112,115that are a part of the gripping assembly110. As illustrated, the gripping members can be actuated towards or away from the centerline of a tubular.

FIG. 4is a perspective view of the gear ring150showing a plurality of ramps205a,210a,215bformed on an inner surface thereof opposite an opening or throat of the ring. The upper and lower ramps205a,210aare constructed and arranged to operate with a set of double wheels305,310(FIG. 5) in order to actuate one gripping member115of the gripping assembly110when a threaded connection is being made. The center ramp215b, as is evident by its direction is constructed and arranged to actuate a single wheel315associated with gripping member112when a connection between tubulars is being broken. An opposite group of ramps, two of which215a,205bare visible inFIG. 4are responsible for a reverse arrangement wherein a second set of double ramps (upper ramp205bis visible) operates with the double wheels305,310to break a connection and a second single ramp215aoperates with the single wheel315when a connection is made.

FIG. 5is a perspective view of the gripping assembly110illustrating the double pair of wheels305,310on a first side and the single wheel315on a second side. The gripping assembly110is made up of two gripping members112,115, each operating like a slip with an inner surface having a concave shape to match the outer surface of the tubular to be grasped by the tong100. As illustrated, the gripping assembly110utilizes the single wheel315associated with one gripping member112and the two-wheel set305,310operating with a second gripping member115. In operation, the wheels (along with the brake plate140) remain rotationally fixed while the gear ring150with its various ramps rotates to a position wherein each wheel has ridden up a ramp. The result is a clamping action forcing the gripping members112,115into contact with the tubular to be grasped. The make or break nature of the operation determines which set of ramps is utilized by the wheels as the tubular is gripped.

FIG. 6is a top view partially in section, taken through one wheel305of the double pair of wheels305,310andFIG. 7is a top view partially in section, taken through the single wheel315. In both Figures, the gripping mechanism is de-activated, meaning that the wheels and ramps are not in contact with one another as indicated by the open position of the gripping members112,155in each Figure. For example, inFIG. 6, upper wheel305of the pair of wheels305,310is visible above the ramp215athat is designed to operate in conjunction with single wheel315when a connection is being made up. Similarly inFIG. 7, on the left side of the Figure, the single wheel315is visible with the lower ramp210bbelow it.

FIG. 8is a top view partially in section, taken through the single wheel315and showing the gripping assembly110actuated around a tubular400. More specifically,FIG. 8is a top section view of the assembly shown inFIGS. 7 and 8with the view taken through the single wheel315. However, inFIG. 8the gear ring150with its sets of ramps has been rotated clockwise while the brake plate140and gripping assembly110have been rotationally held in the same orientation as they are inFIGS. 7 and 8. The result is that the ramps have changed location relative to the wheels305,310,315in a manner whereby the wheels have mounted the ramps215a,205a,210athat are designed to be utilized in actuating the gripping mechanism in order to make a connection. Because the wheels have been actuated by the ramps, the gripping mechanism110is actuated and the tubular400is gripped.

FIG. 9is a top view partially in section, taken through the single wheel315and showing the tubular member400having been rotated in a clockwise direction to make a wellbore connection between tubulars. ComparingFIGS. 8 and 9, inFIG. 9the entire tong unit including gear ring150and brake plate140has been rotated as a unit. In this manner the tubular400retained by the upper portion of the tong100is rotated relative to a tubular gripped by a lower portion (not shown) in order to make a threaded connection. It will be appreciated the operation can be reversed, using the same wheels but operating on another set of ramps having reverse formations. In this manner, the tong assembly can be used to make or break a threaded connection between tubulars.

As described above, in order to actuate the gripping assembly110, the brake plate140and gripping assembly must be rotationally fixed or at least rotationally limited relative to the gear ring while the gear ring150with its inwardly facing ramps rotates to a location whereby the ramps interact with the wheels of the gripping assembly to close the gripping members112,115around a tubular400. Thereafter, the gear wheel150and brake plate140rotate together to make or break a threaded connection. In one embodiment, rotation of the brake plate140is prevented with the use of a brake band160that is tightened around an outer surface of the plate in order to prevent its rotation. The brake band160and braking members165a, bare shown inFIGS. 2 and 3. As shown, the band160extends around an outer perimeter of the plate140and is held at each end by one of the braking members. By holding the band at each end, the brake members can tighten the band160by urging each end towards the door120of the assembly, essentially removing slack in the band and thereby increasing its friction with the side of the brake plate140. In one embodiment, the braking members each include a piston that urges a corresponding end of the brake band160in order to tighten it.

FIGS. 10 and 11are top views showing the operation of one of the braking members165band its relationship with the brake plate140. InFIG. 10the brake is un-actuated as shown by a gap146formed between the band and an outer edge of a brake pad145disposed around an outer edge of the plate.FIG. 11is a similar view however, inFIG. 11the brake band has been tightened as apparent by the absence of gap146in the Figure. Arrow149illustrates the direction of a force placed upon the band in order to tighten it.

One novel aspect of the invention relates to brake pads and their location relative to the brake band and brake plate. In prior art devices, friction and heat generated between the tightened band and brake plate create wear and can cause failure of the entire tong assembly, essentially shutting down operations at a well site. In prior art devices, brake material including non-metallic, semi metallic and ceramic materials has been used on an inner surface of the brake band in order to effect braking between the band and brake plate. In order to extend the life of the brake band and to reduce friction and resulting heat between the surfaces, grease is applied at the intersection of the band and plate. The addition of grease reduces the heat and wear but must be replaced regularly requiring precious time at the working wellsite. Additionally, with or without grease, flexing of the band as it is tightened or loosened can cause the brake material to separate from the band. In one embodiment of the present invention, these problems and others are overcome by placing brake pads made of breaking and friction-reducing material not on the band but on the outer perimeter of the brake plate where it contacts the band.

FIG. 12is a perspective view of the brake plate having apertures142around its perimeter for attachment of brake pads. One exemplary brake pad145is shown in the Figure. By fastening the brake pads with fasteners around the perimeter, a braking surface is provided in a manner whereby the material is protected from the flexing of the brake band. Additionally, the pieces can be replaced in any area where excessive wear has occurred without replacing the entire band or a large strip of the braking material. In one example, the brake pads are constructed primarily of bronze or sintered bronze. Bronze is an alloy consisting primarily of copper, commonly with about 12% tin and often with the addition of other metals and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon.

FIG. 13is a perspective view of another embodiment of a wellbore tong300. The tong300includes a body505and two doors321,322pivotally connected to the body505. The doors321,322are opened to allow ingress or egress of a tubular. The doors321,322can be opened using any suitable manner, such as a piston and cylinder assembly or manually. The tong300includes a gripping assembly having a carrier ring350housing one or more gripping members. It is contemplated that any suitable carrier ring and gripping members, such as those shown inFIGS. 1, 2, 16, and 17may be used.

In one embodiment, the carrier ring350is a segmented carrier ring having a body ring portion and two door ring portions. When the tong300is in the unactivated position, the body ring portion is coupled to the body505, and each door ring portion is coupled to a door321,322. The door ring portion is movable with the respective door321,322, when the door321,322opens or closes. A gear ring (e.g., gear ring459shown inFIG. 17) is coupled to the carrier ring350.

The tong300includes a segmented brake plate340having a body plate343and two door plates341,342. The body plate343is attached to the body ring portion, and each door plate341,342is attached to a door ring portion. The brake plate340is rotatable with the carrier ring350. In this embodiment, the brake plate340is attached to an upper surface of the carrier ring350. In another embodiment, the brake plate340is attached to a lower surface of the carrier ring350. The door plates341,342are movable with the respective door321,322, when the door321,322opens or closes. In one embodiment, a brake pad345is attached to a perimeter wall surface of the brake plate340. An exemplary brake pad345is the brake pad145described inFIGS. 10-12. As discussed, one or more of the brake pads345can be attached to apertures in the perimeter wall surface of the brake plate340. In another embodiment, the brake pads can be attached to the brake band361,362.

In one embodiment, the tong300includes one or more segmented brake bands361,362. As shown inFIG. 13, two brake bands361,362are provided on the tong300. For sake of clarity, only one brake band361will be described.FIGS. 14 and 15show the brake band361disposed on the tong300, which is shown with only one door321.FIG. 14shows the door321in the closed position. The brake band361includes a first band portion371coupled to a second band portion372using a braking member365. In one example, the braking member365such as a cylinder assembly is used to couple the first and second band portions371,372. A piston extends out of one end of the cylinder assembly and is pivotally coupled to one end of each band portion371,372. The outer end of the first band portion371is pivotally coupled to the first door321, such as via a first pin connection376. The outer end of the second band portion372is pivotally coupled to the tong body505, such as via second pin connection377. In one embodiment, the distance between the first and second pin connections376,377is from 25% to 75% of the circumference of the brake plate340or from 35% to 60% of the circumference of the brake plate340. It is contemplated the braking member can be a dual piston and cylinder that pivotally couples the first band portion371and the second band portion372.

FIG. 15shows the door321in the open position. As the door321swings out, the brake band361is allowed to pivot about both pin connections376,377. The band portions371,372also pivot about the connections with the pistons of the braking member365.

The brake band361is shown inFIG. 14in the unactuated position. A gap exists between the brake band361and the brake plate340. To stop rotation of the brake plate340, the braking member365is actuated to tighten the brake band361. For example, one or both of the pistons of the braking member365are retracted to move at least a portion of the brake band361into contact with the brake plate340. As a result, friction between the brake band361and the brake plate340is increased, thereby stopping rotation of the brake plate340and the carrier ring350.

FIG. 16is a perspective bottom view of another embodiment of a wellbore tong400.FIG. 17is a perspective view of the tong400with one door422in the open position. The tong400includes a body405and two doors421,422pivotally connected to the body405. The doors421,422are opened to allow ingress or egress of a tubular. The doors421,422can be opened using any suitable mechanism, such as a piston and cylinder assembly or manually. The tong400includes a gripping assembly having a carrier ring450housing one or more gripping members408.

In one embodiment, the carrier ring450is a segmented carrier ring having a body ring portion453and two door ring portions451,452. When the tong400is in the unactivated position, the body ring portion453is coupled to the body405, and each door ring portion451,452is coupled to a door421,422. The door ring portion451,452is movable with the respective door421,422, when the door421,422opens or closes. A gear ring459is coupled to the carrier ring450and is selectively rotatable relative to the carrier ring450. The gear ring459is segmented to accommodate movement of the door ring portions451,452with the doors421,422.

The tong400includes a segmented brake plate440having a body plate443and two door plates441,442. The body plate443is attached to the body ring portion453, and each door plate441,442is attached to a door ring portion451,452. The brake plate440is rotatable with the carrier ring450. In this embodiment, the brake plate440is attached to a lower surface of the carrier ring450. In another embodiment, the brake plate440is attached to an upper surface of the carrier ring450. The door plates441,442are movable with the respective door421,422, when the door421,422opens or closes. In one embodiment, a brake pad445is attached to a perimeter wall surface of the brake plate440. An exemplary brake pad445is the brake pad145described inFIGS. 10-12. As discussed, one or more brake pads445can be attached to apertures in the perimeter wall surface of the brake plate440. In another embodiment, the brake pads can be attached to the brake band460.

In one embodiment, the tong400includes a brake band460having a plurality of segments461,462,463.FIG. 18shows an exemplary embodiment of the brake band460. The brake band460is disposed around a perimeter of the brake plate440and configured to make contact with the brake plate440. The brake band460includes a body band463coupled to the body405of the tong400. The brake band460may be attached to the body405using a bracket466. One or more retainers467may be used to keep the brake band460in position around the brake plate440. The first and second door bands461,462are coupled to the doors421,422, respectively, and are movable with the doors421,422as the doors421,422open or close. In this embodiment, the door bands461,462are coupled to the doors421,422using a braking member465such as a piston and cylinder assembly. In one embodiment, the door bands461,462include a hinge456for pivotally coupling with the piston of the braking member465. For example, a pin can be inserted through a hole457in the hinge456and a hole in the piston. In this manner, the door bands461,462can be moved by the respective braking member465.

In one embodiment, the door bands461,462are connected to the body band463using a latch470, as shown inFIG. 18. The latch470includes a catch471,472on the door bands461,462for receiving a dog473,474protruding from the body band463. In one example, the catch471,472has a hook shape. When the dog473,474is engaged in the catch471,472, a pull force from the braking member465is transferred to the body band463to tighten the brake band460around the brake plate440. The latch470is configured such that as the doors421,422open, the catch471,472disengages from the dogs473,474.FIG. 17shows the catch471on the first door band461engaged with the dog473on the body band463, and the catch472on the second door band462fully disengaged from the dog474on the body band463.FIG. 19shows the catch471on the first door band461fully disengaged from the dog473on the body band463, and the catch472on the second door band462partially disengaged from the dog474on the body band463.FIG. 20shows the catch471,472on both door bands461,462fully disengaged from the dogs473,474of the body band463as a result of opening the doors421,422.

In operation, the doors421,422are opened to allow a tubular to enter the tong400. As the doors421,422open, the door bands461,462move with the doors421,422and disengage from the dogs473,474on the body band463.FIG. 20shows the door bands461,462disengaged from the body band463. After the tubular enters the tong400, the doors421,422are closed. As the doors421,422rotate back, the catch471,472will engage the respective dog473,474.FIG. 19shows the first door band461still disengaged from the body band463, and the second door band462partially engaged with the door band463. It can be seen the dog474is partially engaged with the catch472on the second door band462. When the doors421,422are closed, the door bands461,462are engaged with the body band463.FIG. 18shows the catch471,472on both door bands461,462engaged with the dogs473,474of the body band463as a result of closing the doors421,422.

To grip a tubular, the braking member465is activated to tighten the brake band460around the brake plate440. The brake band460applies a frictional force against the brake plate440to prevent rotation of the carrier ring450. In this respect, the gear ring459is allowed to rotate relative to the carrier ring450. The gear ring459may act as a cam to urge the gripping members408into contact with the tubular.

FIG. 21is a partial, perspective view of another embodiment of a wellbore tong500.FIG. 22is a perspective view of the tong500with one door522in the open position. Because the tong500has many of the same features described in the tong400shown inFIG. 17, the tong500will be described with respect to only one of the doors522. The door522pivots at the door hinge526relative to the tong body. The door522is opened to allow ingress or egress of a tubular. The door522can be opened using any suitable mechanism, such as a piston and cylinder assembly or manually. The tong500includes a gripping assembly having a carrier ring550housing one or more gripping members. It is contemplated that any suitable carrier ring and gripping members, such as those shown inFIGS. 16 and 17may be used.

In one embodiment, the carrier ring550is a segmented carrier ring having a body ring portion and two door ring portions, e.g., carrier ring450ofFIGS. 16, 17. Only one door522is shown inFIG. 22. The door ring portion is movable with the door522, when the door522opens or closes. However,FIG. 22shows the door ring portion in the closed position while the door522is open in order to more clearly show the features of the brake band560.

The tong500includes a segmented brake plate540having a body plate543and two door plates541,542. The body plate543is attached to the body ring portion, and each door plate541,542is attached to a door ring portion. The brake plate540is rotatable with the carrier ring550. In this embodiment, the brake plate540is attached to a lower surface of the carrier ring550. In another embodiment, the brake plate540is attached to an upper surface of the carrier ring550. The door plate542is movable with the respective door522, when the door522opens or closes. In one embodiment, a brake pad is attached to a perimeter wall surface of the brake plate540. An exemplary brake pad is the brake pad145described inFIGS. 10-12. As discussed, one or more brake pads can be attached to apertures in the perimeter wall surface of the brake plate540.

In one embodiment, the tong500includes one or more brake bands560for holding or stopping rotation of the carrier ring550. InFIG. 22, the brake band560is coupled to the door522. While not shown, another brake band560is preferably coupled to the other door. The brake band560includes a first segment561pivotally coupled to a second segment562. In another embodiment, the brake band560is a single segment or includes three or more segments. A first end of the brake band is pivotally coupled to a braking member565, and a second end of the brake band is pivotally coupled to the tong body. In this embodiment, a band hinge plate563is attached to the tong body. The first segment561of the brake band560is pivotally attached to a pin574on the door hinge plate563. In this embodiment, a hinge cut out528is formed in the door hinge plate527to accommodate the pin574and the door band560. The second segment562is pivotally attached to a hinge567of the braking member565. The hinge567extends from the piston of the braking member565and is movable with the piston.

In operation, the doors of the tong500are opened to allow a tubular to enter the tong500. For sake of clarity, only the operation of one of the doors522will be described. As the door522opens, the brake band560moves with the door522and pivot about the pin574on the band hinge plate575. The brake band560also pivots relative to the braking member565. The piston of the braking member565also moves the hinge567as the door522opens.FIG. 22shows the brake band560in the open position with the door522. After the tubular enters the tong500, the door522is closed. As the door522rotates back, the brake band560will rotate with the door522about the pivotal connections574,567.FIG. 20shows the brake band560in the closed position. The hinge567has moved from the position shown inFIG. 22. The braking member565is activated to tighten the brake band560around the brake plate540. The brake band560applies a frictional force against the brake plate540to prevent rotation of the carrier ring550. In this respect, a gear ring is allowed to rotate relative to the carrier ring550, thereby urging the gripping members into contact with the tubular.

FIG. 23is a partial, perspective view of another embodiment of a wellbore tong600.FIG. 24is a perspective view of the tong600with one door621in the open position. Because the tong600has many of the same features described in the tong400shown inFIG. 17, the tong600will be described with respect to only one of the doors621. The other door is not shown for sake of clarity. The door621pivots at the door hinge626relative to the tong body605. The door621is opened to allow ingress or egress of a tubular. The door621can be opened using any suitable mechanism, such as a piston and cylinder assembly or manually. The tong600includes a gripping assembly having a carrier ring (such as carrier ring450ofFIGS. 16, 17) and a gripping member, which are not shown for sake of clarity. It is contemplated that any suitable gripping assembly, such as those shown inFIGS. 1-2 and 16-17may be used. In one embodiment, the carrier ring is a segmented carrier ring having a body ring portion and two door ring portions. The door ring portion is movable with the door621, when the door621opens or closes.

The tong600includes a segmented brake plate640having a body plate643and two door plates641,642. The body plate643is attached to the body ring portion, and each door plate641,642is attached to a door ring portion. The brake plate640is rotatable with the carrier ring. In one embodiment, the brake plate640is attached to a lower surface of the carrier ring. In another embodiment, the brake plate640is attached to an upper surface of the carrier ring. The door plate641is movable with the respective door621, when the door621opens or closes. In one embodiment, a brake pad645is attached to a perimeter wall surface of the brake plate640. An exemplary brake pad is the brake pad145described inFIGS. 10-12. As discussed, one or more brake pads can be attached to apertures in the perimeter wall surface of the brake plate640.

In one embodiment, the tong600includes a brake band660having a plurality of segments.FIG. 23shows an exemplary embodiment of the brake band660. The brake band660is disposed around a perimeter of the brake plate640and configured to make contact with the brake plate640. The brake band660includes a body band663coupled to the body605of the tong600. The brake band660may be attached to the body605using a bracket and one or more retainers may be used to keep the brake band660in position around the brake plate640. The brake band660also includes a first door band661and a second door band. For sake of clarity, this embodiment will be described with respect to the first door band661since the second door band operates in a similar manner. The first door band is coupled to the door621and is movable with the door621as the door621opens or closes. The first door band661is coupled to the door621using a braking member665such as a piston and cylinder assembly. In one embodiment, the first door band661includes a hinge for pivotally coupling with the piston of the braking member665. For example, a pin can be inserted through a hole in the hinge and a hole in the piston. In this manner, the first door band661can be moved by the respective braking member665.

In one embodiment, the door bands661are connected to the body band663using a guide slot670, as shown inFIG. 23. In this embodiment, the guide slot670is attached to the body band663. A pin671on the first door band661is disposed in the guide slot670. The guide slot670is configured to accommodate movement of the pin671as the first door621opens or closes. In one example, the guide slot670has a curved shape. The pin671may be coupled to the first door band661using an adapter674. InFIG. 23, the first door621is in a closed position. When a pull force from the braking member665is applied to the first door band661, the pull force is transferred from the first door band661to the body band663via the pin671and guide slot670. In this respect, the braking member665can apply the pull force to tighten the brake band660around the brake plate640.FIG. 24shows the first door621in the open position. The pin671has moved outwardly with the first door621and along the guide slot670.

In operation, the doors of the tong600are opened to allow a tubular to enter the tong600. For sake of clarity, only the operation of one of the doors621will be described. As the door621opens, the first door band661moves with the door621and the pin671of the first door band661moves along the guide slot670.FIG. 24shows the door621and the first door band661in the open position. After the tubular enters the tong600, the door621is closed. As the door621rotates back, the pin671of the first door band661moves back along the guide slot670toward the body band663.FIG. 23shows the door621and the first door band461in the closed position. The braking members665are activated to tighten the brake band660around the brake plate640. Force from the braking member665is applied to the first door band661and transferred to the body band663via the pin671and the guide slot670. The brake band660applies a frictional force against the brake plate640to prevent rotation of the carrier ring550. In this respect, the gear ring is allowed to rotate relative to the carrier ring550, thereby urging the gripping members into contact with the tubular.

In one embodiment, a method of operating a tong includes opening a door of the tong. The tong may include a tong body; the door pivotally coupled to the tong body; a carrier ring rotatable relative to the tong body; a brake plate coupled to the carrier ring; and a brake band having a door band portion attached to the door. The method also includes moving the door band portion of the brake band with the door as the door opens; closing the door; rotating the carrier ring; and moving the brake band into contact with the brake plate, thereby stopping rotation of the carrier ring.

In one embodiment, a tong for use at a wellbore includes a tong body; at least one door pivotally coupled to the tong body and movable between an open position and a closed position; a carrier ring rotatable relative to the tong body; a brake plate coupled to the carrier ring; a brake band configured to move with the at least one door between the open and closed positions; and a braking member for moving the brake band into contact with the brake plate to stop rotation of the carrier ring.

In one embodiment, a tong for use at a wellbore includes a tong body; at least one door pivotally coupled to the tong body and movable between an open position and a closed position; a gripping assembly rotatable relative to the tong body; and a brake plate coupled to the gripping assembly. The tong may also include a brake band configured to move with the at least one door between the open and closed positions; and a braking member for moving the brake band into contact with the brake plate to stop rotation of the gripping assembly.

In one or more of the embodiments described herein, the brake band includes a body band attached to the tong body; and a door band attached to and movable with the door, wherein the door band is engaged with the body band when the door is in the closed position, and the door band is disengaged from the body band when the door is in the open position.

In one or more of the embodiments described herein, the door band includes a catch configured to receive a dog of the body band when the door is in the closed position.

In one or more of the embodiments described herein, the braking member is attached to the door.

In one or more of the embodiments described herein, the brake plate includes a body plate attached to the tong body and a door plate attached to and movable with the door.

In one or more of the embodiments described herein, the tong includes a first door and a second door, and the brake band includes a body band attached to the tong body; a first door band attached to and movable with the first door; and a second door band attached to and movable with the second door, wherein the first and second door bands are engaged with the body band when the doors are in the closed position, and the first and second door bands are disengaged from the body band when the doors are in the open position.

In one or more of the embodiments described herein, the first end of the brake band is pivotally attached to the door, and a second end of the brake band is pivotally attached to the tong body.

In one or more of the embodiments described herein, the second end of the brake band is pivotally attached to a pin on the tong body.

In one or more of the embodiments described herein, the braking member is attached to the door, and wherein the first end of the brake band is pivotally coupled to the braking member.

In one or more of the embodiments described herein, the brake band includes a first brake band portion pivotally coupled to a second brake band portion.

In one or more of the embodiments described herein, the door includes a hinge cut out to accommodate the pin.

In one or more of the embodiments described herein, the brake band includes a first brake band portion pivotally coupled to a second brake band portion.

In one or more of the embodiments described herein, the braking member pivotally couples the first brake band portion to the second brake band portion.

In one or more of the embodiments described herein, the braking member includes a first piston coupled to the first brake band portion and a second piston coupled to the second brake band portion.

In one or more of the embodiments described herein, the tong includes a first door and a second door, wherein the first end of the brake band is pivotally attached to the first door and the second end of the brake band is pivotally attached to the tong body. The tong may further include a second brake band having a first end pivotally attached to the second door and a second end pivotally attached to the tong body.

In one or more of the embodiments described herein, the brake band includes a body band attached to the tong body and having a guide slot; and a door band attached to and movable with the door, wherein the door band is coupled to the guide slot.

In one or more of the embodiments described herein, the door band includes a pin disposed in the guide slot.

In another embodiment, a method of operating a tong includes opening a door of the tong, wherein the tong includes a tong body; the door pivotally coupled to the tong body; a carrier ring rotatable relative to the tong body; a brake plate coupled to the carrier ring; and a brake band having a door band portion attached to the door. The method also includes moving the door band portion of the brake band with the door as the door opens; closing the door; moving the brake band into contact with the carrier ring, thereby preventing rotation of the carrier ring; and rotating a gear ring relative to the carrier ring.

In one or more of the embodiments described herein, moving the door band portion includes disengaging the door band portion from a body band portion of the brake band attached to the tong body.

In one or more of the embodiments described herein, closing the door includes engaging the door band portion with the body band portion.

In one or more of the embodiments described herein, moving the brake band into contact includes transferring a force from the door band portion to the body band portion.

In one or more of the embodiments described herein, moving the door band portion includes moving a pin of the door band portion along a guide slot of a body band portion of the brake band.

In one or more of the embodiments described herein, moving the brake band into contact with the brake plate includes actuating a braking member to apply a force to the brake band to move the brake band relative to the brake plate.