US3380323A - Power wrench - Google Patents

Description

April 30, 1968 A. B. CAMPBELL 3,380,323

POWER WRENCH Filed Feb. 15, 1966 5 Sheets-Sheet 1 I I I 74- g LN] 1M i i I I I 0 90 94 J I O O 7? firm/roe.

ANDREW ,8. (32441 5524, (-83 Ms flrmeueg: Himms, 1615a,, floss-e2: 5K

April 30, 1968 A. s. CAMPBELL POWER WRENCH 5 Sheets-Sheet .3

Filed Feb. 15, 1966 INVENTOR. Av qew r51 (EMPBEAL B MS firm/easy: .HlQR/S, 6155, flussszz Mp April 30, 1968 Filed Feb. 15, 1966 A. B. CAMPBELL POWER WRENCH 5 Sheets-Sheet 5 April 1963 A. B. CAMPBELL 3,380,323

POWER WRENCH Filed Feb. 15, 1966 5 Sheets-Sheet 4 133 INVENTOR. 66 Amman/,5. @MPBELL,

J RP/S Mam flussezz. #1456 12 United States Patent 0 3,380,323 PSWER WRENCH Andrew B. Campbell, San Marino, Califi, assignor to Hillman-Kelley, Los Angeles, Calif., a partnership Filed Feb. 15, 1966, Ser. No. 527,720 2 Claims. ((31. 8154) ABSTRACT OF THE DISCLOSURE A power wrench comprising a housing, an annular rotor rotatable relative to the housing, a reversible motor for rotating the rotor in either direction, a jaw assembly carried by the rotor and rotatable relative thereto about the rotor axis, a brake for restraining the jaw assembly to enable the rotor to rotate relative thereto, a double acting cam system for closing the jaw assembly in response to rotation of the rotor relative to the jaw assembly in either direction, a first set of stops on the rotor and the jaw assembly for preventing rotation of the rotor relative to the jaw assembly in one direction to prevent the cam system from closing the jaw assembly, a second set of stops on the rotor and the jaw assembly for preventing rotation of the rotor relative to the jaw assembly in the other direction to prevent the cam assembly from closing the jaw assembly, and a control system for selectively interengaging the stops of the first set and the stops of the second set. The control system includes a control lever extending circumferentially of the rotor and sloping downwardly in the direction of jaw-closing rotor rotation.

Backgrmmd of invention The present invention relates in general to power tongs or wrenches and, more particularly, to a power wrench for making or breaking threaded joints in pipe or rod strings when running such strings into or out of oil wells, for example. Still more particularly, the invention relates to a power wrench capable of lateral engagement with and disengagement from the pipe or rod string, as by mounting it for lateral swinging movement into and out of engagement with the pipe or rod string.

The invention contemplates a power wrench of the foregoing type which includes a housing, an annular rotor carried by the housing, reversible drive means for rotating the rotor in either direction, jaw means mounted on the rotor in such a manner as to permit limited rotation of the rotor relative to the jaw means in either direction, double-acting cam means for closing the jaw means in response to limited rotation of the rotor relative to the jaw means in either direction from a neutral position, braking means for restraining the jaw means upon rotation of the rotor in either direction to actuate the cam means and thus close the jaw means, and spring means for biasing the jaw means open in opposition to the action of the cam means so that the jaw means opens when it is in its neutral position relative to the rotor. Preferably, the housing, the rotor and the jaw means are provided with registerable radial throats permitting radial insertion of a pipe or rod string into the jaw means into a position to be gripped by the jaw means upon closing thereof.

With the foregoing construction, the double-acting cam means closes the jaw means in response to rotation of the rotor in either direction, as long as the braking means restrains the jaw means in order to permit the rotor to rotate relative to the jaw means in either direction from the relative neutral positions of the rotor and the jaw means. Consequently, the power wrench can be used for making or breaking a joint in a pipe or rod string merely by reversing the direction of rotation of the rotor.

Patented Apr. 30, 1968 Preferably, the braking means acts on the jaw means continuously so that the braking means continuously tends to produce rotation of the rotor relative to the jaw means upon rotation of the rotor in either direction. With this construction, the double-acting cam means automatically tends to close the jaw means in response to rotation of the rotor in either direction. Consequently, no means for actuating the braking means is required.

However, there are times during the operation of a power wrench of the foregoing nature when it is necessary or desirable to rotate the rotor in one direction or the other without closing the jaw means on a pipe or rod string therein. For example, after making or breaking a joint in a pipe or rod string, it is necessary to reverse the direction of rotor rotation to register the radial throats in the rotor and the jaw means with the radial throat in the housing so that the power wrench may be laterally disengaged from the pipe or rod string. Initially, such reversed rotor rotation opens the jaw means to disengage same from the pipe or rod string, and it is necessary to keep the jaw means open as the reversed rotor rotation continues to register the radial throats in the jaw means and the rotor with the radial throat in the housing. Otherwise, the previously-completed joint making or breaking operation would be at least partially reversed, which obviously would be undesirable.

Summary and objects of invention With the foregoing as background, the primary object of the invention is to provide means for preventing rotation of the rotor relative to the jaw means, in opposition to the continuous drag exerted on the jaw means by the braking means, when closing of the jaw means is not desired. This permits concurrent rotation of the rotor and the jaw means, with the jaw means open, for the purpose of aligning the radial throats in the jaw means and the rotor with the radial throat in the housing, or for other purposes, which is an important feature of the invention.

More particularly, an important object of the invention is to provide means for preventing jaw-means-closing rotation of the rotor relative to the jaw means which includes: firs-t interengageable stop means on the rotor and the jaw means for preventing rotation of the rotor relative to the jaw means in one direction to prevent the cam means from closing the jaw means; second interengageable stop means on the rotor and the jaw means for preventing rotation of the rotor relative to the jaw means in the other direction to prevent the cam means from closing the jaw means; and control means for selectively interengaging the first stop means and the second stop means.

Another important object of the invention is to provide a power wrench of the foregoing nature wherein: the first stop means includes a first fixed stop on the jaw means, and includes a first movable stop carried by the rotor and movable relative to the rotor from an extended position wherein it is engageable with the first fixed stop to a retracted position; the second stop means includes a second fixed stop on the jaw means, and includes a second movable stop carried by the rotor and movable relative to the rotor from an extended position wherein it is engageable with the second fixed stop to a retracted position; and the control means includes a control lever which has first and second ends respectively connected to the first and second movable stops, and which is pivotal ly mounted on the rotor intermediate its ends.

Still another object of the invention is to provide a power wrench wherein the first and second movable stops are spaced apart circumferentially of the rotor and the first and second fixed stops are spaced apart circumferentially of the jaw means, and wherein the control lever extends circumferentially of the rotor.

An additional object is to provide a construction of the foregoing nature wherein tilting the control lever relative to the rotor in a particular circumferential direction will result in closing of the jaw means when the rotor is rotated relative to the housing in that direction. Thus, it is a simple matter for the operator to determine visually whether the jaw means will close or not upon rotation of the rotor in one direction or the other, which is an important feature.

Another object of the invention is to provide first and second fixed stops on the rotor respectively engageable with the first and second fixed stops on the jaw means, after predetermined rotational displacements of the rotor relative to the jaw means in opposite directions, to limit the maximum rotational displacement of the rotor relative to the jaw means which can occur.

Yet another object of the invention is to provide a jaw means which includes two jaws and to provide a doubleacting cam means which includes means for closing both jaws in response to rotation of the rotor relative to the jaw means in either direction from a neutral position.

A further object of the invention is to provide a braking means which includes a stack of three flat, annular, disc-like braking elements having their planes perpendicular to the axis of rotation of the rotor, and which includes spring means for clamping the intermediate braking element between the other two, whereby the braking elements cooperate to restrain the jaw means, upon rotation of the rotor in either direction, to actuate the cam means for closing the jaw means. A related object is to provide a braking means of the foregoing character wherein at least one of the braking elements, preferably the intermediate braking element, is carried by the housing, the remainder being carried by the jaw means.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results of the invention which will be evident to those skilled in the power wrench art in the light of this disclosure, may be achieved with the exemplary embodiments of the invention described in detail hereinafter and illustrated in the accompanying drawings.

Description of drawings In the drawings:

FIG. 1 is a perspective view of an apparatus for making or breaking threaded joints in pipe or rod strings when running such strings into or out of oil wells, for example, which apparatus includes the power wrench of the invention;

FIG. 2 is a vertical sectional view of the power wrench which is taken as indicated by the arrowed lines 22 of FIGS. 1 and 3;

FIG. 3 is a sectional view taken as indicated by the arrowed line 33 of FIG. 2, and shows a jaw means of the power wrench of the invention in its open position;

FIG. 4 is a fragmentary sectional view similar to FIG. 3, and shows the jaw means in its closed position;

FIG. 5 is a fragmentary plan view of the portion of the power wrench of the invention which is shown in FIG. 4;

FIG. 6 is a fragmentary sectional view taken as indicated by the arrowed line 66 of FIG. 2;

FIG. 7 is a fragmentary sectional view taken as indicated by the arrowed line 77 of FIG. 4;

FIG. 8 is a fragmentary sectional view similar to the bottom part of FIG. 2, but showing an alternative and presently preferred braking means of the invention;

FIG. 9 is a sectional view taken as indicated by the arrowed line 9-9 of FIG. 8; and

FIG. 10 is a fragmentary sectional view taken as indicated by the arrowed line 1010 of FIG. 9 of the drawings.

Description of preferred embodiment of invention Referring initially to FIG. 1 of the drawings, illustrated therein is an apparatus 20 of the invention for making or breaking threaded joints in pipe or rod strings, such as a threaded joint 22 in a drill string 24. The entire apparatus 20 is shown as suspended from a hook 26 at the lower end of a cable, not shown, so that it may be swung laterally into and out of engagement with the drill string 24.

More particularly, the apparatus 20 includes a vertical post 28 shown as having at its upper end an eye 30 engageable with the hook 26. The power tongs or wrench of the invention is designated generally by the numeral 32 and is suitably carried by the post 28. As will become apparent, the power wrench 32 is designed to be engaged with or disengaged from an upper section 34 of the drill string 24 by swinging it to the left or right, as viewed in FIG. I of the drawings. It will be noted that, in the particular construction illustrated, the power wrench 32 is intended to engage the upper drill-string section 34 above the threaded joint 22 between the upper section 34 and a lower section 36. The threaded joint 22 may be of the usual pin and box type, the pin being formed at the lower end of the upper section 34 and the box being formed at the upper end of the lower section 36.

The apparatus 20 is also shown as including a backup tongs or wrench 38 engageable with the box at the upper end of the lower drill-string section 36 to prevent rotation thereof while making or breaking the joint 22. The back-up wrench 38, which is more fully described and claimed by my co-pending application Ser. No. 543,329, filed Apr. 18, 1966, is pivotable about a subpost into and out of engagement with the box at the upper end of the lower drill-string section 36, after the power wrench 32 has been swung laterally into engagement with the upper drill-string section 34. The subpost 40 is telescoped upwardly into a socket aligned with the post 28 and is detachably connected thereto by a suitable connector 42. The back-up wrench 38 is supported on the subpost 40 by a compression spring 44 seated on a removable pin 46. By removing the pin 46 and the spring 44, the back-up wrench 38 may he slipped downwardly off the lower end of the subpost 40 so that it can be turned over and re-installed on the subpost upside down relative to the position shown in FIG. I of the drawings. With this construction, the position of the back-up wrench 38 on the subpost 40 can be reversed readily when switching from making threaded joints to breaking them, or vice versa. The back-up wrench 38 per se forms no part of the present invention, and since it is fully disclosed in my aforementioned co-pending application, it will not be described further herein.

Considering the power wrench 32 of the invention more specifically now, with particular reference to FIGS. 3 to 6 of the drawings, it includes a housing 50 carried by the post 28 and provided with a radial throat 52 for lateral application of the power wrench to and lateral disengagement thereof from the upper drill-string section 34. The outer end of the radial throat 52 is normally closed by two pivoted, spring-biased guards 54 which open and close automatically as the power wrench 32 is applied to and disengaged from the upper drill-string section 34. Guards of this nature are well known in the power tongs art so that a further description of the guards 54 is not necessary.

Rotatable in the housing 50 about an axis paralleling that of the post 28 is an annular rotor 56 having a radial throat 58 registerable with the radial throat 52, as shown in FIG. 3, when the power wrench 32 is to be applied to or disengaged from the drill string 24. As shown in FIGS. 2 and 7 of the drawings, the rotor 56 is rotatably mounted in the housing 50 by means of upper and lower rollers 60 and 62 respectively engageable with upper and lower cylindrical surfaces 64 and 66 of the rotor, which cylindrical surfaces are, of course, interrupted by the radial throat 58. The weight of the rotor 56 is supported by the upper ends of the lower rollers 62, which engage an annular surface 68 of the rotor 56 in a plane perpendicular to the axis of rotation of the rotor. The foregoing mounting of the rotor 56 in the housing is generally conventional so that a detailed description is not required.

The power wrench 32 includes a reversible drive means 70 for rotating the rotor 56 relative to the housing 50 in either direction. Referring to FIG. 1, the reversible drive means 70 includes a suitable motor 72 mounted on the housing 50. Preferably, the motor 72 is a hydraulic motor having connected thereto supply and return lines 74 and 76 which are flexible to permit lateral swinging of the power wrench 32 into and out of engagement with the drill string 24.

The motor 72 may be reversible to drive the rotor 56 in either direction, or a suitable reversing means, not shown, may be interposed between the motor and the rotor. In either event, the direction of rotation of the rotor 56 is controlled by a suitable control lever 78, FIG. 1, carried by the housing 50.

Continuing to consider the reversible drive means 70, it includes a suitable gear train 80, FIG. 3, one end of which is appropriately connected to the motor 72 and the other, or output, end of which is connected to the rotor 56. More particularly, the output end of the gear train 80 includes two circumferentially spaced gears 82 meshed with a peripheral gear 84 on the rotor 56. Providing the output end of the gear train 80 with the two circumferentially spaced gears 82 insures that one of them will always be in mesh with the peripheral gear 84 on the rotor 56, which peripheral gear is interrupted by the radial throat 58 in the rotor. The foregoing connections between the rotor 56 and the motor 72 are more-orless conventional so that a further description is unnecessary.

The power wrench 32 includes a control system 86 for starting and stopping the motor 72, which control system comprises pivoted control levers 88 carried by hand grips 90 on the housing 50 on opposite sides of the radial throat 52 therein. The control system 86 also includes means 92, FIGS. 3 and 4, for stopping the rotor 56 with its radial throat 58 in register with the radial throat 52 in the housing 50. The control system 86 is more fully described and claimed in the co-pending application of Fred J. Hillman, Ser. No. 543,280, filed Apr. 18, 1966, and assigned to the same assignee as the present application. The disclosure of the co-pending application just mentioned is incorporated herein by reference the same as if it were fully set forth herein.

The power wrench 32 further includes jaw means 94 mounted on the rotor 56 in such a manner as to permit limited rotation of the rotor relative to the jaw means in either direction. More particularly, the jaw means -94 includes a jaw carrier 96 having a radial throat 98 registerable with the radial throat 58 in the rotor 56 when the jaw carrier is in a neutral position relative to the rotor. The jaw carrier 96 is provided with cylindrical upper and lower ends 102 and 104 (interrupted by the radial throat 98) which are rotatable relative to the rotor 56 in combined journal and thrust bearing recesses 106 and 108, respectively, in the rotor.

The cylindrical upper and lower ends 102 and 104 of the jaw carrier 96 are interconnected by spaced, parallel, chordal guide walls 110 and 112 located on opposite sides of the common axis of rotation of the rotor 56 and the jaw carrier. The radial throat 98 is formed in the guide wall 110.

Disposed between the guide walls 110 and 1-12 are two radially inwardly and outwardly movable, diametrically-opposed jaw members 114 carrying jaws 116 engageable with the drill string 24. The jaws 116 are shown in engagement with the upper drill-string section 34 in FIGS. 4 and 6 of the drawings, and are shown out of engagement with such drill-string section in FIG. 3 thereof. Preferably, the jaws 116 comprise removable inserts secured to the jaw members 114 by means of dovetail-like joints. With this construction, other jaws, not shown, for other pipe or rod sizes may be substituted for the jaws 116.

The jaw members 114 are biased apart, i.e., toward their open positions, by a leaf spring 118 disposed between the cylindrical upper and lower ends 102 and 104 of the jaw carrier 96 on the opposite side of the jaw carrier from the radial throat 98 therein. The ends of the leaf spring 118 project through windows 120 in the guide wall 112 into grooves 122 in the respective jaw members 114. The leaf spring 118 normally assumes the configuration shown in FIG. 3 of the drawings to bias the jaw members 114 outwardly into their open positions. When the jaw members 114 are forced inwardly into their closed positions in a manner to be described, the leaf spring 118 assumes the configuration shown in FIG. 4 of the drawings.

The power wrench 32 further includes double-acting cam means for closing the jaw means 94 upon rotation of the rotor 56 relative to the jaw means in either direction away from the relative neutral positions of the rotor and the jaw means. This double-acting cam means includes two roller cam followers 124 respectively carried by the jaw members 114 and respectively disposed in diametrically-opposite detent recesses 126 in the rotor 56 when the rotor and the jaw means 94 are in their relative neutral positions. Upon rotation of the rotor 56 in the counterclockwise direction relative to the jaw means 94, as shown in FIG. 4 of the drawings, the cam followers 124 respectively engage radially-inwardly-spiraling cams 128 on the rotor 56 to close the jaws 116 on the drill string 24. Conversely, upon clockwise rotation of the rotor 56 relative to the jaw means 94 from their relative neutral positions, the cam followers 124 respectively engage radially-inwardly-spiraling cams 130 on the rotor, which cams also act to close the jaws 116. Thus, upon rotation of the rotor 56 relative to the jaw means 94 in either direction, the jaws 116 are closed, being closed by the interaction of the cam followers 124 and the cams 128 in one direction of relative rotation, and being closed by the interaction of the cam followers and the cams 130 in the other direction of relative rotation.

The power wrench 32 is provided with continuouslyoperating braking means 132 for restraining the jaw means 94 upon rotation of the rotor '56- in either direction so that the cams 128, or the cams 130, close the jaws 116.

As suggested in FIGS. 2 and 4, the braking means 132 may comprise a brake band 134 secured to the housing 50 and encircling a brake drum 136 on the jaw carrier 96, the brake band 134 being provided with a brake lining 138 engageable with the brake drum. The brake band 134 is suitably secured at its ends to the housing 50 on opposite sides of the radial throat 52 in the housing, as disclosed, for example, in Patent No. 2,618,468, granted Nov. 18, 1952, to Chester A. Lundeen.

An alternative, and presently preferred, braking means 140 of the invention is illustrated in FIGS. 8 to 10 of the drawings. The braking means 140 comprises flat, annular, disc- like braking elements 142, 144 and 146 having their planes perpendicular to the axis of rotation of the rotor 56 and positioned in stacked relation with the braking element 144 between the braking elements 142 and 146. The intermediate braking element 144 is secured to the housing 50, as by inserting a lug 148 thereon into an opening 150 in the housing. It will be understood that the intermediate braking element 144 has a gap therein corresponding to the radial throat 52 in the housing 50. The other braking elements 142 and .146, which have gaps therein coinciding with the radial throat 98 in the jaw carrier 96, are carried by screws 152 threaded into the lower end of the jaw carrier. The screws 152 are surrounded by compression springs 154 which are seated at their upper ends against the lower end of the jaw carrier 96 and which are seated at their lower ends against the braking element 142 to clamp the intermediate braking element 144 between the upper and lower braking elements 142 and 146. Thus, the braking means 140 exerts a continuous restraint on the jaw means 94 tending to produce rotation of the rotor 56 relative to the jaw means upon rotation of the rotor relative to the housing 50.

The description which follows is applicable irrespective of whether the braking means 132 of FIGS. 2 to 7, or the braking means 140 of FIGS. 8 to 10, is used.

As will be apparent, irrespective of the direction of rotation of the rotor 56, the braking means 132 or 140 restrains the jaw means 94 against rotation to cause the cams 128 or 130 to close the jaws 116 on the drill string 24. Consequently, the power wrench 32 may be used for making or breaking the threaded joint 22 merely by reversing the direction of rotation of the rotor 56. In either case, the jaws 116 grip the drill string section to which the power wrench 32 is applied with a clamping force proportional to the torque applied to the rotor 56.

As hercinbefore outlined, there are times during the operation of the power wrench 32 when it is necessary or desirable to rotate the rotor 56 in one direction or the other without closing the jaw means 94 on a pipe or rod string therein. For example, after making or breaking the threaded joint 22, it is necessary to reverse the direction of rotor rotation to first open the jaws 116 and to then register the radial throats 98 and 58 in the jaw means 94 and the rotor 56 with the radial throat S2 in. the housing 50 so that the power wrench 32 can be disengaged from the drill string 24. During this throat-registering operation, the jaw means 94 must be kept open to prevent at least partial reversal of the previously-completed joint making or breaking operation.

The invention provides means 160 for preventing rota tion of the rotor 56 relative to the jaw means 94, in opposition to the continuous drag exerted on the jaw means by the braking means 132 or 141), when closing of the jaw means is not desired. This permits concurrent rotation of the rotor 56 and the jaw means 94, with the jaws 116 open, for the purpose of aligning the radial throats 98 and 58 in the jaw means 94 and rotor 56 with the radial throat 52 in the housing 50, or for other purposes. For example, it may simply be desirable under some circumstances to rotate the rotor 56 in one direction or the other without rotating it relative to the jaw means 94 to close the jaw means.

More particularly, the means 160 for preventing jawclosing rotation of the rotor 56 relative to the jaw means 94 includes: first interengageable stop means 162 on the rotor and the jaw means for preventing rotation of the rotor relative to the jaw means in the clockwise direction to prevent the cams 130 from closing the jaw means; second interengageable stop means 164 on the rotor and the jaw means for preventing rotation of the rotor relative to the jaw means in the counterclockwise direction to prevent the cams 128 from closing the jaw means; and control means 166 for selectively interengaging the first stop means and the second stop means.

As best shown in FIG. 6 of the drawings, the first and second stop means 162 and 164 respectively include first and second fixed stops 168 and 176 on the jaw means 94, these fixed stops being formed by circumferentially spaced ends of an arcuate, circumferentially extending rib 172 on the jaw carrier 96 and disposed in a circumferential groove 174 in the rotor 56. The first and second stop means 162 and 164 also include first and second movable stops 178 and 180 movable vertically between extended and retracted positions and respectively engageable with the fixed stops 168 and 170, when in their extended positions, in response to clockwise and counterclockwise rotation, respectively, of the rotor 56 relative to the jaw means 94. As best shown in FIGS. 2 and of the drawings, the

first and second movable stops 1'78 and 180 comprise pins vertically movable between upper, retracted and lower, extended positions in bores 182 and 184 in the rotor 56. The upper ends of the first and second movable stops 178 and 180 are pivotally connected to first and second ends 188 and 190 of a circumferential]y-extending control lever 192 which constitutes the control means 166 and which is pivotally mounted intermediate its ends, at 194, on the rotor 56.

Considering the operation of the means for preventing jaw-closing rotation of the rotor 56 relative to the jaw means 94, and referring particularly to FIGS. 2 and 4 of the drawings, it will be assumed that the control lever 192 is in the position shown in FIG. 2 and that the rotor 56 is being rotated in the counterclockwise direction, as indicated by the arrow 196 in FIG. 4. Under such conditions, the jaw means 94 is restrained by the braking means 132 or 140 to cause the cam followers 124 and the cams 128 to cooperate to close the jaws 116 on the drill-string section 34. It will be noted that with the control lever 192 in the position shown in FIG. 2, the second movable stop 180 is in its retracted position so that it cannot engage the second fixed stop to prevent closure of the jaw means 94. It will also be noted that the control lever 192 is tilted relative to the rotor 56 in the direction of rotor rotation which will produce closing of the jaw means 94. Thus, it is a simple matter for the operator to determine visually that the jaw means 94 will close when the control lever 192 is tilted downwardly in the counterclockwise direction and the rotor 56 is rotated in that direction.

After the rotor 56 has been rotated in the counterclockwise direction sufliciently to break the threaded joint 22 completely, the direction of rotor rotation is reversed, without changing the position of the control lever 192. Initially, the rotor 56 rotates relative to the jaw means 94 until the rotor and the jaw means are in their relative neutral positions, with the cam followers 124 in their detent recesses 126. Under such circumstances, the jaw means 94 is fully open. Continued rotor rotation in the clockwise direction under such circumstances cannot result in re-closing of the jaw means 94 because of the fact that the first movable stop 178 engages the first fixed stop 168 to prevent jaw-closing rotation of the rotor 56 relative to the jaw means 94. In other words, the first stop means 162, comprising the first fixed stop 168 and the first movable stop 178, precludes jaw-closing rotation of the rotor 56 relative to the jaw means 94.

The power wrench 32 has a similar mode of operation when it is desired to make the joint 22. Under such conditions, the control lever 192 is tilted downwardly inthe clockwise direction so that the first movable stop 178 can clear the first fixed stop 168 when the rotor 56 is rotated in the clockwise direction. Under such conditions, the jaw means 94 closes on the drill string section 34. Upon reversed rotation, however, the jaw means 94 opens and does not re-close upon continued reversed rotation.

Thus, in either case, the rotor 56 can rotate relative to the jaw means 94 to close the jaw means as long as the direction of rotor rotation corresponds to the direction of downward inclination of the control lever 192. However, if the direction of rotor rotation is the reverse of the direction of downward inclination of the control lever 192, the jaw means 94 merely opens and then remains open upon continued reversed rotation of the rotor. This permits registering the radial throats 98 and 58 in the jaw means 94 and rotor 56 without re-closing of the jaw means, which is an important feature of the invention.

The power wrench 32 also includes circumferentiallyspaced first and second fixed stops 198 and 200 on the rotor 56 and respectively engageable with the first and second fixed stops 168 and 170 on the jaw means 94 to limit the maximum possible relative rotation of the rotor relative to the jaw means in the clockwise and counterclockwise directions, respectively. Preferably, the fixed stops 198 and 200 are simply fixed pins carried by the rotor and respectively engageable with the ends 168 and 170 of the arcuate, circumferentially extending rib 172. Considering the purpose of the fixed stops 198 and 200 with reference to FIG. 4 of the drawings, if the rotor 56 were inadvertently driven in the counterclockwise direction without a pipe or rod between the jaws 116, it would be possible for the cam followers 124 to run off the ends of the cams 128. However, this is prevented by engagement of the fixed stop 200 on the rotor 56 with the fixed stop 170 on the jaw means 94. These fixed stops produce rotation of the jaw means 94 with the rotor 56 in opposition to the restraining action of the braking means 132 or 140, thereby preventing the cam followers 124 from running off the ends of the cams 128. The fixed stops 168 and 198 perform a similar function during clockwise rotation of the rotor 56 with no pipe or rod between the jaws 116.

Referring to FIG. 2 of the drawings, the relative-rotation-limiting actions of the fixed stops 198 and 200 are supplemented by fixed stops 202 and 204 on the rotor 56 and respectively engageable with fixed stops 206 and 208 on the jaw means 94. The fixed stops 202 and 204 are preferably fixed pins aligned with the fixed pins 198 and 200, and the fixed stops 206 and 208 are preferably the ends of an arcuate, circumferentially extending rib 210 coinciding with the rib 172.

Although exemplary embodiments of the invention have been disclosed herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiments without departing from the spirit of the invention as defined by the claims which follow.

I claim as my invention:

1. In a power wrench, the combination of:

(a) a housing;

(b) a generally horizontal annular rotor carried by said housing and rotatable relative to said housing about a generally vertical axis;

(c) reversible drive means carried by said housing for rotating said rotor in either direction;

((1) outwardly openable and inwardly closable jaw means carried by said rotor and rotatable relative to said rotor about said axis;

(e) braking means on said housing and said jaw means for restraining said jaw means upon rotation of said rotor in either direction to enable said rotor to rotate relative to said jaw means in either direction;

(f) double-acting cam means on said rotor and said jaw means for closing said jaw means in response to rotation of said rotor relative to said jaw means in either direction from a neutral position;

(g) first interengageable stop means on said rotor and said jaw means for preventing rotation of said rotor relative to said jaw means in one direction to prevent said cam means from closing said jaw means;

(h) second interengageable stop means on said rotor and said jaw means for preventing rotation of said rotor relative to said jaw means in the other direction to prevent said cam means from closing said jaw means;

(i) control means for selectively interengaging said first stop means and said second stop means;

(j) said first stop means including a first fixed stop on said jaw means, and including a first movable stop carried by said rotor and movable relative to said rotor from a lower, extended position wherein it is engageable with said first fixed stop to an upper, retracted position;

(k) said second stop, means including a second fixed stop on said jaw means, and including a second movable stop carried by said rotor and movable relative to said rotor from alower, extended position wherein it is engageable with said second fixed stop to an upper, retracted position;

(1) said first and second movable stops being spaced apart circumferentially of said rotor and said first and second fixed stops being spaced apart circumferentially of said jaw means;

(m) said control means including a control lever which extends circumferentially of said rotor, which has first and second ends respectively connected to said first and second movable stops, and which is pivotally mounted on said rotor intermediate its ends;

(n) said control lever sloping circumferentially downwardly toward said first movable stop when said first movable stop is in its lower, extended position and said second movable stop is in its upper, retracted position, and said control lever sloping circumferentially downwardly toward said second movable stop when said second movable stop is in its lower, extended position and said first movable stop is in its upper, retracted position; and

(0) whereby the circumferential direction of downward inclination of said control lever corresponds to the direction of rotation of said rotor required to close said jawrmeans.

2. A power wrench according to claim 1 wherein said control lever is an arcuate member the center of curvature of which lies on the axis of rotation of said rotor.

References Cited UNITED STATES PATENTS 425,370 4/1890 Coyle l94--12 2,550,045 4/1951 De Hetre 8157.13 2,618,468 11/1952 Lundeen 81--57.1 2,766,684 10/1956 Newmaster et a1. 188-83 X 2,846,909 8/1958 Mason 8157.1 X 3,103,357 9/1963 Borne 18872 X 3,261,241 7/1966 Cotland 8157.l

FOREIGN PATENTS 334,635 1/1936 Italy.

JAMES L. JONES, JR., Primary Examiner.

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