Powered tool for tightening threaded connections

Abstract

There is provided herein a powered tool for tightening threaded connections, comprising: a housing (1600) comprising a slotted opening (200); a slotted gear (120, 210) mechanism comprising a slotted gear (120, 210) and a plurality of rotating gripper cams; a transmission plate (130) rotationally coupled to the slotted gear (120, 210), wherein the transmission plate (130) is linked to the gripper cams via the slotted gear (120, 210) mechanism such that rotation of the transmission plate (130) causes rotation of the gripper cams; a biasing means arranged to urge the transmission plate (130) such that the gripper cams are rotated towards the circumference of the housing (1600); and a linkage, in mechanical communication with both the slotted gear (120, 210) and the transmission plate (130), comprising a biased ratchet (105), the linkage arranged such that: rotation of the slotted gear (120, 210) in a first direction causes the linkage to engage on the ratchet (105), thereby rotating the transmission plate (130) to compress the biasing means and rotate the gripper cams such that, in use, their grip on a bar (135) passing through the slotted housing (1600) is loosened; and rotation of the slotted gear (120, 210) in a second direction causes the transmission plate (130) to rotate and rotate the gripper cams such that, in use, their grip on a bar (135) passing through the slotted housing (1600) is tightened.

Description

POWERED TOOL FOR TIGHTENING THREADED CONNECTIONSBackground

[0001] Reinforcing bars, commonly known as "rebars," are steel bars used to reinforce concrete structures by adding tensile strength to the material. In reinforced concrete structures, rebars are joined together to form a network of interconnected bars that provide additional strength and durability to the structure. Two common methods of joining rebars are lapping and screwing.

[0002] Lapping involves laying two rebars next to each other and locking them together by pouring concrete around them. This creates an overlapping region where the two rebars are connected, which increases the overall strength of the structure. Screwing involves connecting two rebars end-to-end using a screwed connector. Screwed connectors are devices that allow two rebars to be rotated relative to each other and then locked in place. These connectors are typically set to a pre-defined torque, which ensures that the joint is strong enough to withstand the loads it will experience over the life of the structure.Summary

[0003] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0004] There is provided herein a compact and automated tool for tightening standard rebar connectors. Other types of bar may additionally or alternatively be used in conjunction with this tool. A slotted drive gear is placed over the connector barrel or rebar. Rotation in one direction causes finger cams, also referred to interchangeably as gripper cams or clamping fingers, to lock on, transferring rotation to the barrel or bar.

[0005] The slope on the finger cam may be such that significant forces are generated perpendicular to the surface of the barrel or bar. If there is external resistance to the barrel or bar rotating, then the finger cams lock on harder, enabling higher torque to be transferred. The torque applied via the drive gear is monitored and recorded to confirm the correct connector setting torque is applied.

[0006] Reverse rotation of the slotted drive gear causes the finger cams to loosen on the connector barrel or rebar. Reverse rotation continues until the slot in the slotted drive gearaligns with the slot in the housing. During the last stages of alignment the finger cams may retract fully into the slotted gear such that the tool can be removed ready for positioning on the next connector.

[0007] The combination of finger cam angles and activation mechanism result in a side access “slot over” tool that can manage a relatively large diametric range of couplers and bars. This makes the tool more versatile in use, with fewer tools necessary to cover the range of coupler diameters encountered on a construction site.

[0008] A first aspect provides a powered tool for tightening threaded connections, comprising: a housing comprising a slotted opening; a slotted gear mechanism comprising a slotted gear and a plurality of rotating gripper cams; a transmission plate rotationally coupled to the slotted gear, wherein the transmission plate is linked to the gripper cams via the slotted gear mechanism such that rotation of the transmission plate causes rotation of the gripper cams; a biasing means arranged to urge the transmission plate such that the gripper cams are rotated towards the circumference of the housing; and a linkage, in mechanical communication with both the slotted gear and the transmission plate, comprising a biased ratchet, the linkage arranged such that: rotation of the slotted gear in a first direction causes the linkage to engage on the ratchet, thereby rotating the transmission plate to compress the biasing means and rotate the gripper cams such that, in use, their grip on a bar passing through the slotted housing is loosened; and rotation of the slotted gear in a second direction causes the transmission plate to rotate and rotate the gripper cams such that, in use, their grip on a bar passing through the slotted housing is tightened.

[0009] A further aspect provides a method of tightening threaded connections, comprising: using a powered tool having: a housing comprising a slotted opening; a slotted gear mechanism comprising a slotted gear and a plurality of rotating gripper cams; a transmission plate rotationally coupled to the slotted gear, wherein the transmission plate is linked to the gripper cams via the slotted gear mechanism such that rotation of the transmission plate causes rotation of the gripper cams; a biasing means arranged to urge the transmission plate such that the gripper cams are rotated towards the circumference of the housing; and a linkage, in mechanical communication with both the slotted gear and the transmission plate, comprising a biased ratchet: the method comprising: rotating the slotted gear in a first direction causing the linkage to engage on the ratchet, thereby rotating the transmission plate to compress the biasing means and rotate the gripper cams such that, in use, their grip on a bar passing through the slotted housing is loosened; and rotating the slotted gear in a second direction causing the transmission plate to rotate and rotate the gripper cams such that, in use, their grip on a bar passing through the slotted housing is tightened.

[0010] The preferred features may be combined as appropriate, as would be apparent to a skilled person, and may be combined with any of the aspects of the invention.Brief Description of the Drawings

[0011] Embodiments of the invention will be described, by way of example, with reference to the following drawings, in which:

[0012] Figure 1 shows a cross sectional view of a tool for screwed rebar connections;

[0013] Figure 2 shows a start condition for the tool;

[0014] Figure 3 shows the tool as it begins clockwise rotation;

[0015] Figure 4 shows the tool as the clamping fingers first touch the bar;

[0016] Figure 5 shows the tool as the bar is beginning to rotate;

[0017] Figure 6 shows the tool as the bar continues to rotate;

[0018] Figure 7 shows the tool as the bar continues to rotate further;

[0019] Figure 8 shows how rotation increases until a predetermined torque;

[0020] Figure 9 shows the tool beginning anti-clockwise rotation;

[0021] Figure 10 shows the tool continuing to perform anti-clockwise rotation;

[0022] Figure 11 shows the tool further continuing to perform anti-clockwise rotation;

[0023] Figure 12 shows a state at which the clamping fingers of the tool are fully retracted;

[0024] Figure 13 shows a state at which the slotted gear of the tool is at rest;

[0025] Figure 14 shows further detail with respect to the clamping fingers;

[0026] Figure 15 shows the tool gripping bars of different sizes;

[0027] Figure 16 shows an external view of an exemplary housing for the tool;

[0028] Figure 17 shows an external view of the underside of the exemplary housing;

[0029] Figure 18 shows a top view of the tool with the upper housing removed;

[0030] Figure 19 shows three views of the tool, with the slotted gear having undergone different amounts of rotation; and

[0031] Figure 20 shows a similar view to Figure 19, but with the top part of the slotted gear removed.

[0032] Common reference numerals are used throughout the figures to indicate similar features.Detailed Description

[0033] Embodiments of the present invention are described below by way of example only. These examples represent the best ways of putting the invention into practice that are currently known to the Applicant although they are not the only ways in which this could be achieved. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

[0034] Where rebars being joined are axially well aligned and threads are clean, a threading or tightening process can be carried out with relative ease. In practical construction environments, bars are rarely aligned and threads can be dirty. This increases the torque required to form a sufficiently robust connection. If most of the thread can no longer be threaded by hand, the time and effort taken to perform the construction increase significantly when a construction worker is required to use a wrench.

[0035] Typically, as bar and connector sizes increase, so the required torque increases. A point is reached where the effort itself becomes significant, slowing the tightening operation further. Since connector make up will typically lie on the critical path of a construction plan, the slow progress on tightening connectors can slow down an entire project. Further, on large sites the labour available may be restricted, meaning labour used screwing up connectors is preventing progress elsewhere.

[0036] Therefore, described herein a tool that enables an electric motor to power the rotation of a connector part. Since the tool may be reusable, the means for transferring torque to the connector cannot involve a complete encircling of a rebar or connector part, as this could render the tool permanently fixed to a bar. In practice, the tool may be presented to a rebar or connector from a side, and so may be removable from the same side once the connector is made up to the correct torque.

[0037] Optionally, a two part open plain bearing is used, one part mounted on the slotted gear, the other part in the tool housing. In this manner, the slotted gear can rotate without being locked onto a rebar or coupler. The bearing may be formed from bronze, brass, plastic, or any other material capable of enduring the necessary stresses and strains. A selflubricating material may be used to form at least a portion of the bearing.

[0038] The locking mechanism may comprise a plurality of, for example five, finger cams that are activated by rotation of the gear. The finger cam arranged to swing over the gear slot may be arranged to extend out first. Continued gear rotation in the same direction may then cause all finger cams to extend in unison, capturing the bar or connector. Subsequent rotation causes the finger cams to grip the bar or connector. The shape of the finger cams is such that the higher the torque required, the greater the clamping force. Optionally, the finger cams may have a substantially “teardrop” shape profile.

[0039] Unlocking is achieved by reverse rotation, compared with the locking rotation. This removes the pressure on the finger cams, which slide over the bar surface. As the gear slot approaches alignment with the slot in the housing, a lever on the housing engages with an actuating lever on the slotted gear and withdraws the clamping fingers. The gear stops in alignment with the housing slot, and the tool may be removed from the bar.

[0040] The tool may be arranged to accommodate with bars and connecters of a variable range of diameters. This enables a single tool to be used in a variety of situations.

[0041] Optionally, the tool is equipped with a digital memory, processor, and / or other electronic equipment arranged to store a memory and / or database of all the bars and / or connectors that have been tightened. Such a record may provide useful a useful checklist for construction workers, all well as avoiding unnecessary reinspection.

[0042] The weight of the tool may be within the handling limits of a human user, such as a construction worker, but may nevertheless be towards the heavy end of such a limit. For this reason the tool may be provided without an integral motor drive unit, although this could be integral in other embodiments. A specific gearbox may be selected for weight reduction.

[0043] The tool may be used according to the following steps:

[0044] In a first step, the tool is slotted over a bar or connector part to be rotated. The tool weight may be supported on a hoist or counterbalance system.

[0045] In a second step, the tool is wedged to prevent rotation as it tightens, typically against adjacent rebar.

[0046] In a third step, a battery powered hand drill is connected to the drive gearbox and activated in the forward direction. This releases the clamping fingers which grip onto the bar or connector. Subsequent rotation causes the bar or connector part to rotate.

[0047] In a fourth step, forward rotation continues until the required torque, optionally as set on the battery hand drill, is reached.

[0048] In a fifth step, reverse rotation is then activated. Reverse rotation continues until the gear and housing slots align, at which stage the clamping fingers have withdrawn.

[0049] In a sixth step, the tool is removed from bar or connector.

[0050] Figure 1 shows a number of components of an exemplary clamping finger operating mechanism, also referred to as a coupling module 100. The rotating transmission plate 130 moves relative to a slotted gear (not shown). The clamping fingers 120 (partially shown) are mounted on shafts which have bearing surfaces through the body of the slotted gear. A finger lever 125 attaches to one end of the shaft, the clamping finger 120 to the other. Rotation of the transmission plate 130 causes rotation of the finger levers 125 and hence of the clamping fingers 120. A system of closing springs 115 act on the rotating transmission plate 130, causing it to rotate the clamping fingers 120 such that they close the clamping fingers 120 onto a bar 135. It is appreciated that other biasing means than springs may be used in any or all of the applications herein. The process of “closing” the clamping fingers 120 is when the clamping fingers 120 rotate so as to move at least partially away from the circumference of the slotted gear 210, thereby, in use, gripping a bar 135 placed within the slotted gear 210. The process of “opening” the clamping fingers 120 is when the clamping fingers 120 rotate in an opposite direction so as to move at least partially towards from the circumference of the slotted gear 210, thereby, in use, loosening the grip on a bar 135 placed within the slotted gear 210.

[0051] Figure 1 also shows an exemplary open lever system 105, also referred to as a ratchet 105. The small open lever 105 may pivot in both directions (as further shown in Figure 7). In a first direction there is a soft spring 105’ such that the open lever 105 easily pivots out of the way of the actuating lever 110. In a second direction there is a hard spring 105” such that the rotating transmission plate 130 is rotated relative to the slotted gear as the actuating lever 110 catches on the open lever 105. However, if the gear rotates more than a predetermined amount, the rotating transmission plate 130 will reach the end of its travel andlock relative to the slotted gear. Further rotation of the slotted gear may cause mechanical damage to either the open lever 105 or the actuating lever 110. The hard spring 105” is rated to compress before such damage occurs. The open lever system 105 may be mounted on the housing (not shown).

[0052] Figures 2-8 show the sequence for tightening up a coupler:

[0053] Figure 2 shows a start condition. A gear slot 200 is aligned with the slot in the housing (not shown). The actuation lever 110 is engaged on the open lever 105. The rotating transmission plate 130 has rotated relative to the slotted gear 210. This compresses the springs 115. In this condition the slotted gear 210 can be positioned over a bar 135. The finger levers 120 have been rotated by the rotating transmission plate 130 such that the clamping fingers 120 are fully retracted. The open lever 105 is indexed to the transmission plate 130 such that under continued rotation, optionally anticlockwise rotation, alignment of the slotted opening of the housing with a slotted opening 200 of the slotted gear 210 coincides with the slotted opening 200 being substantially clear of any portion of the finger levers 120. This allows for the ingress and egress of bars or other equipment on which tightening is to be performed.

[0054] Figure 3 shows the arrangement as the gear 210 starts to turn clockwise. It is appreciated that the tool may alternatively be configured such that anticlockwise rotation of the gear 210 closes the clamping fingers 120 over the bar 135, and clockwise rotation of the gear 210 loosens the clamping fingers 120 over the bar 135. A first clamping finger 120’ closing over the slot immediately start to rotate. Since the pins 305 linking the finger levers 120 with the transmission plate 130 run in slots 310 for the other clamping fingers 120, they remain in their start position (or move out due to nominal friction in the system, but are unable to apply any force). Continued rotation of the gear 210 results in a relative rotation of the transmission plate 130 as the actuating lever 110 is still engaged with the open lever 105. Rotation continues until the transmission plate 130 has rotated sufficient for the pins 305 linking the finger levers 120 to have all reached the end of their respective slots 310. At this point the transmission plate 130 causes all the clamping fingers 120 to rotate out in unison.

[0055] Figure 4 shows the situation where transmission plate 130 rotation has continued until the clamping fingers 120 contact a bar 135. At this point the arrangement locks up. It is then not possible for the transmission plate 130 to rotate relative to the gear 210. The closing springs 115 continue to apply an initial clamping force to the transmission plate 130. The actuating lever 110 now loses contact with the open lever 105. The shape of the clamping fingers 120 result in the bar 135 being gripped. The higher the torque needed to rotate the bar135, the more the clamping fingers 120 grip. Once sufficient grip has been attained, the bar 135 will rotate with the gear 210.

[0056] Figures 5 and 6 show the situation where the gear is in the process or rotating the bar. In Figure 5, the clamping fingers 120 have been automatically rotated by the closing spring 115. The closing spring 115 has been released. In Figure 6 the actuating lever is just about to contact the open lever.

[0057] Figure 7 shows the situation where there has been further rotation. The actuating lever 110 is now in contact with the open lever 105 which is pushed out of the way since the soft spring 105’ of the open lever 105 provides lower resistance than the hard spring 105” of the open lever 105.

[0058] Figure 8 shows how rotation continues until a predetermined torque, such as a torque pre-programmed into the tool, is reached. As a screwed coupling tightens, the setting torque of the coupler will be reached. This may be determined by an input torque of a battery operated screwdriver being used to rotate the slotted gear 210. Once the coupler torque has been reached, it is necessary to remove the slotted gear 210 from the bar. To do this the clamping fingers 120 must be retracted back under the slotted gear 210. Since there may be a housing provided (not shown), which also has a slot as well as the gear 210, the two slots must be aligned.

[0059] The procedure for releasing the gear 210 is described with reference to Figures 9-13.

[0060] Figure 9 shows the slotted gear starting to rotate anti-clockwise. As it does, the clamping fingers 120 relax pressure on the bar 135 enabling rotation without undoing the screwed coupler. The closing springs 115 maintain a predetermined amount of pressure on the clamping fingers 120. The actuating lever 110 is not engaged with the open lever.

[0061] Figure 10 shows that as rotation continues, the actuating lever 110 engages with the open lever 105. The open lever 105 is held in position in this direction by the strong spring 105”, hence it does not hinge out the way.

[0062] Figure 11 shows that as anti-clockwise rotation continues, the actuating lever 110 is caught by the open lever 105. The rotating transmission plate 130 starts to rotate relative to the slotted gear 210, pulling back first the slot covering clamping finger 120’ and then the other clamping fingers 120. Rotation causes the closing springs to be compressed.

[0063] Figure 12 shows that as the slot 200 in the gear 210 aligns with the slot in the housing (not shown), all the clamping fingers 120 been fully retracted. At this stage the transmission plate 130 locks up relative to the slotted gear 210. Accidental further anticlockwise rotation of the slotted gear may cause damage as the actuating lever 110 cannot pass the open lever 105. Damage is prevented by the open lever 105 hinging out of the way first, before damage can be cased. The force at which this happens may be carefully predetermined, as the open lever 105 must not hinge out the way until all the clamping fingers 120 are fully retracted and the closing springs 115 are compressed. However, the opening lever 105 must hinge out the way before damage occurs.

[0064] Figure 13 shows the slotted gear 210 at rest. The bar 135 may now be pulled out of the gear slot 200, or, in use, the tool pulled off the bar 135. Figure 13 is similar to Figure 2, which shows the start of the tool use process.

[0065] As shown in Figure 14, for the clamping fingers 120 to grip onto the bar, it is necessary that they don’t slip on a bar 135 or connector barrel. Slip may be at least partially prevented by having serrated teeth on the clamping fingers 120 and applying a degree of preload via the transmission plate and closing springs. However, in some cases, the spring force 1405 alone may not be enough to transmit the torque necessary to tighten a coupler or rotate the bar 135. The shape of the clamping fingers may be designed so that rotation of the slotted gear 210 in the clockwise direction results in an increasing frictional force 1410 perpendicular to the surface of the bar 135 where the bar 135 and clamping finger 120 touch. This perpendicular force 1410 causes the clamping fingers 120 to grip the bar. The clamping finger 120 geometry may be selected so that the tangential grip force 1415, causing the bar to rotate, is always greater than the torque required. Alternatively or additionally, the clamping fingers 120 may have a bar contact profile, comprising a flat surface that is oriented perpendicular to the direction of motion of the clamping fingers 120, which allows them to make contact with a relatively large surface area of the bar 135. One or more of the forces applied at the reaction point may be measured by one or more strain gauges so that the torque applied to the bar 135 can be determined and controlled.

[0066] Figure 15 shows a range of bar 135 sizes that the tool in this example is capable of achieving. Figure 15A shows the tool gripping a smaller diameter bar 135’. Figure 15B shows the tool gripping a larger diameter bar 135”. The clamping fingers 120 are arranged to only extend from under the transmission plate 130 until the bar 135 is sufficiently gripped. In this example, the smaller diameter bar 135’ has a diameter of 25mm, and the larger diameter bar 135” has a diameter of 46mm. It is appreciated that other diameters of bar 135 may be used in conjunction with this tool, both larger and smaller than the examples provided.

[0067] Figure 16 shows an external view of an exemplary housing 1600 used to cover one or more mechanical parts of the tool. A gearbox 1610 may be provided on a first side, and the slotted gear 120 on another side. The open lever system 105 for opening the clamping fingers 120 may be arranged between the gearbox 1610 and the slotted gear 120. A handle 1605, and a lifting eye 1615, may be provided on the housing 1600 to assist a use position the tool over the bar 135.

[0068] Figure 17 shows a view of the underside of a similar housing 1600. An additional handle 1705 is shown, which may be used to help the user position the tool over the bar 135.

[0069] Figure 18 shows a top view with the upper housing 1600 removed. In this example, the gearbox 1610 is on the right side, with a square socket 1805 to connect with a battery powered drill. The gearbox 160 outputs to a large overdrive (OD) gear, which transfers drive via two idler gears to the slotted gear 210. An overdrive gear is a type of gear that has a higher gear ratio than 1 :1 , resulting in the output shaft of the gearbox 1610 turning faster than the input shaft connected to the socket 1805. This may improve efficiency of power transfer and reduce wear on the tool. As the slotted gear 210 rotates, the gap 200 in the gear teeth will pass over one of the idler gears 1810. Drive is maintained by the other idler gear 1810. In this manner a full 360 degree revolution can be made without loss of drive.

[0070] Figure 19 shows three views of the tool, with the slotted gear 210 having undergone different amounts of rotation. It can be seen from this Figure how the clamping fingers 120 have extended as the rotation takes place.

[0071] Figure 20 shows a similar view to Figure 19, but with the top part of the slotted gear 210 removed so as to show greater detail of the internal mechanism. This shows the mechanism for extending the clamping fingers 120 more clearly.

[0072] Any range or device value given herein may be extended or altered without losing the effect sought, as will be apparent to the skilled person.

[0073] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages.

[0074] Any reference to 'an' item refers to one or more of those items. The term 'comprising' is used herein to mean including the method blocks or elements identified, but that suchblocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements.

[0075] The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought.

[0076] It will be understood that the above description of a preferred embodiment is given by way of example only and that various modifications may be made by those skilled in the art. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention.

Claims

Claims1 . A powered tool for tightening threaded connections, comprising: a housing comprising a slotted opening; a slotted gear mechanism comprising a slotted gear and a plurality of rotating gripper cams; a transmission plate rotationally coupled to the slotted gear, wherein the transmission plate is linked to the gripper cams via the slotted gear mechanism such that rotation of the transmission plate causes rotation of the gripper cams; a biasing means arranged to urge the transmission plate such that the gripper cams are rotated towards the circumference of the housing; and a linkage, in mechanical communication with both the slotted gear and the transmission plate, comprising a biased ratchet, the linkage arranged such that: rotation of the slotted gear in a first direction causes the linkage to engage on the ratchet, thereby rotating the transmission plate to compress the biasing means and rotate the gripper cams such that, in use, their grip on a bar passing through the slotted housing is loosened; and rotation of the slotted gear in a second direction causes the transmission plate to rotate and rotate the gripper cams such that, in use, their grip on a bar passing through the slotted housing is tightened.

2. The tool of any preceding claim, wherein the biased ratchet is a sprung ratchet.

3. The tool of claim 2, wherein the sprung ratchet comprises a soft spring in a first direction and a hard spring in a second direction,4. The tool of claim 3, wherein the hard spring has a spring rate set to allow deflection of the ratchet at predetermined stress levels within the slotted gear mechanism.

5. The tool of any preceding claim, wherein the transmission plate comprises one or more slotted holes.

6. The tool of claim 5, wherein the one or more slotted holes control the point at which rotation of the transmission plate causes one or more of the gripper cams to rotate.

7. The tool of any preceding claim, wherein one or more of the gripper cams has any of: a bar contact profile, and / or serrated teeth.

8. The tool of claim 7, wherein the serrated teeth are oriented to, in use, dig into a bar surface under rotation of the slotted gear in the second direction, and perform a sharpening action when running over a bar surface under rotation of the slotted gear in the first direction.

9. The tool of any preceding claim, wherein the slotted gear is rotationally held in position by an open plain bearing located between the slotted gear and the housing.

10. The tool of any preceding claim, wherein the slotted gear is driven by one or more idler gears.11 . The tool of claim 10, wherein the one or more idler gears are driven by a single drive gear.

12. The tool of claim 10 or 11 , wherein the idler gear spacing is such that the slotted gear remains driven at all times.

13. The tool of claim 11 , wherein the single gear is driven by a motor assembly.

14. The tool of claim 13, wherein the motor assembly comprises a gearbox.

15. The tool of claim 13 or 14, wherein the motor is separate from the tool and is connected either to a gearbox or directly to the single drive gear via a socket.

16. The tool of any preceding claim, wherein the housing is operable to substantially encapsulate two or more bars in contact with one another.

17. The tool of any preceding claim, further comprising one or more strain gauges.

18. The tool of any preceding claim, wherein the ratchet is indexed to the transmission plate such that under rotation in a first direction, alignment of the slotted opening of the housing with a slotted opening of the slotted gear coincides with the slotted opening being substantially clear of any portion of the gripper cams.

19. A method of tightening threaded connections using a powered tool as claimed in any preceding claim.

20. A method of tightening threaded connections, comprising: using a powered tool having: a housing comprising a slotted opening; a slotted gear mechanism comprising a slotted gear and a plurality of rotating gripper cams; a transmission plate rotationally coupled to the slotted gear, wherein the transmission plate is linked to the gripper cams via the slotted gear mechanism such that rotation of the transmission plate causes rotation of the gripper cams; a biasing means arranged to urge the transmission plate such that the gripper cams are rotated towards the circumference of the housing; and a linkage, in mechanical communication with both the slotted gear and the transmission plate, comprising a biased ratchet: the method comprising: rotating the slotted gear in a first direction causing the linkage to engage on the ratchet, thereby rotating the transmission plate to compress the biasing means and rotate the gripper cams such that, in use, their grip on a bar passing through the slotted housing is loosened; and rotating the slotted gear in a second direction causing the transmission plate to rotate and rotate the gripper cams such that, in use, their grip on a bar passing through the slotted housing is tightened.

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