Open End Ratchet Wrench

Abstract

An open end ratchet wrench is made from three parts: The wrench body, a single ratcheting pawl, and a spring actuator for retaining the pawl in its operating position and actuating the pawl to permit insertion of a nut. In one embodiment the pawl is pivotally mounted about the end of one wrench jaw between drive and open positions. This wrench is provided with three drive surfaces for contacting the nut during drive operation, including the drive surface of the pawl, the inner surface of the jaw opposite the pawl, and a projection from the working surface between the jaws contoured to contact the nut approximately 120.degree. from the other two contact points. The working surface is further contoured to provide room for the pawl to swing clear from the nut during ratcheting and to permit the nut to contact as much of the working surface as possible during ratcheting. In a second embodiment, the pawl is both pivotable and slidable with respect to a slot in the wrench jaw and has two drive surfaces for engaging a nut in two different nut positions relative to the wrench jaws. In this embodiment the working surface is contoured to accommodate the nut in both of its drive positions and provides three-point drive contact in at least one of these positions. Moreover, the adjacent surfaces of the pawl and wrench jaw are contoured to prevent binding of the pawl during ratcheting, irrespective of the point about which the wrench is rotated. In yet another embodiment two drive positions of the nut are made possible without the necessity of a pawl actuator to permit nut insertion by providing two pawls, rotatable about opposite jaws, and arranged so that each has its drive surface contacting the nut in a respective one of the nut drive positions. With the pawls in their normally retracted position the wrench jaws may be slipped over a nut head.

Description

BACKGROUND OF THE

This invention relates to new and improved wrenches, and more particularly to open-end ratchet wrenches of simple construction and capable of imparting greater torque to a nut or bolt to be driven than is possible with prior art open-end ratchet wrenches.

Open-end ratchet wrenches have heretofore been characterized by complex designs featuring large numbers of coacting movable elements and close tolerances. In addition, prior art wrenches of this type are usually characterized by a number of undesirable features which limit their utility, among which are: a lack of compactness which renders them impractical in limiting working space; insufficiently rugged construction making their jaws vulnerable to excessive spreading and even rupture under the relatively heavy loads to which this type of wrench is often subjected; and a high cost to manufacture.

Accordingly, an important object of the present invention is to provide a wrench construction which will obviate the foregoing disadvantages characterizing known wrench structures.

Another primary object of this invention is to provide an improved open-end ratchet wrench.

A further object of this invention is to provide an open-end ratchet wrench having sufficient strength for conventional utility yet constructed of a minimum number of parts.

Still another object of the present invention is to provide an improved open-end ratchet wrench characterized by simplicity of design and capable of performing satisfactorily for those who must adjust fittings and other fasteners which are connected to tubing, shafting, conduit, cable and the like in a coaxial manner.

Still another object of this invention is to provide a new and improved open end ratchet wrench which is easy to manufacture, functional in design, and low in cost.

Another object of the present invention is to provide a novel open-end ratchet wrench having a single ratcheting element and which is capable of driving a nut or bolthead in at least two positions of the nut or bolthead relative to the jaws of the wrench.

Yet another object of the present invention is to provide an open-end ratchet wrench having a single ratcheting element yet which maintains substantial contact with a nut or bolthead during ratcheting operation.

It is another object of the present invention to provide an open-end ratchet wrench which requires no actuating device to enable the wrench to be slipped into working engagement over a nut or bolthead.

It is another object of the present invention to provide an open-end ratchet wrench having a minimum number of parts and which is capable of smoothly ratcheting about a hexagonal nut or bolthead with a minimum resolution of 30.degree..

It is alleged by the manufacturers of certain open-end ratchet wrenches that they are capable of providing a smooth ratcheting action. Upon a superficial observation of these wrenches these allegations appear to be true; however, when one attempts to use these wrenches, their ratcheting capability is found to be somewhat limited. More particularly, depending upon the point about which the wrench handle is rotated during ratcheting operation, the smoothness of the ratcheting varies. This is due to the fact that the ratcheting element tends to bind (i.e., frictionally engage the wrench body) to a greater degree for some pivot points than for others. Thus, the user of the wrench is forced to jiggle the wrench considerably during ratcheting operation in order to free the ratcheting element from frictional engagement with the wrench body. Consequently there is a distinct need for an open-end ratchet wrench which is capable of smooth ratcheting action for every possible point about which the wrench handle may be rotated during ratchet operation.

Thus it is another object of the present invention to provide an open-end ratchet wrench which is simple in construction and capable of smooth ratcheting action irrespective of the point about which the wrench handle is pivoted during ratchet operation.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention an open-end ratchet wrench employs a single ratcheting pawl and consumes no more space than a conventional open-end wrench of the nonratcheting type. The pawl is rotatable over the end of one wrench jaw between a drive position, in which a drive surface of the pawl engages a surface of the nut, and an open position in which the pawl is completely clear of the working area between the wrench jaws. In the drive position the working surface of the pawl provides one of three drive points which engage the nut or boltheads, the other two drive points comprising the inner surface of the opposite wrench jaw and a projecting portion of the working surface between the wrench jaws, this projecting portion being displaced approximately 120.degree. from the other two drive points.

The end of the jaw about which the pawl rotates is of reduced thickness to provide a shoulder at the junction of that jaw end and the remainder of the wrench working head. A pivot hole is defined transversely through the wrench head near the juncture of the shoulder and the outer contour of the working head. The pawl has a cylindrical portion which is journaled in the pivot hole and two support members which depend from this cylindrical portion along opposite sides of the jaw end to the working surface of the pawl, whereby the pawl structure substantially encircles a portion of the jaw end about which it is designed to rotate. A compression spring extends through the working head to retain the pawl in a position whereby the depending members abut the shoulder between the jaw end and working head. When a nut or bolthead is placed between the wrench jaws in position to be driven, the pawl experiences only compressive rather than tensile or torsional forces and therefore is capable of transmitting relatively large forces to the driven element without rupturing. By selectively compressing the retention spring for the pawl it is possible to swing the pawl over the end of the jaw, the inner surface of which is cut back to permit the pawl to be swung clear of the working area and therefore permit relatively easy insertion of a nut or bolthead between the wrench jaws.

In another aspect of the present invention, a wrench of the type described above is provided with a second pawl which encircles and is rotatable about the opposite wrench jaw in a similar manner. The pawls are arranged so that the working surfaces of each engages a nut or bolthead to be driven in different respective one of two possible driving positions of the nut relative to the wrench jaws. In addition the second wrench jaw is cut back sufficiently so that when both spring-loaded pawls are in their retained position the working head of the wrench can be slipped over a nut or bolthead without the need for an actuating mechanism for either pawl.

In still another aspect of the present invention a nut or bolthead, for example, of hexagonal configuration, may be driven from either two possible positions relative to the wrench jaws, yet only a single pawl member is required to provide a ratcheting capability. In this embodiment, the pawl includes two drive surfaces, each engaging a driven element in a different drive position of that element relative to the wrench jaws. The pawl in this embodiment is both pivotable about and slidable along the end of one wrench jaw so that the pawl may be pushed away from the nut or bolthead during ratchet operation and yet rotated as required so that the appropriate pawl drive surface engages the driven element in a respective one of the two drive positions. Adjacent surfaces of the pawl and working head are contoured so that the pawl, during ratcheting operation, can be displaced from work area without significant frictional engagement, irrespective of the point about which the wrench handle is pivoted.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of specific embodiments thereof, especially when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a view in perspective of one embodiment of the open-end ratcheting wrench of the present invention;

FIG. 2 is an enlarged fragmentary plan view of the working head of the wrench of FIG. 1, with a nut disposed between the wrench jaws in position to be driven;

FIG. 3 is an enlarged fragmentary plan view of the working head of a modified version of the wrench of FIG. 1, with a nut illustrated between the wrench jaws in one of two drive positions;

FIG. 4 is identical to FIG. 3 with the nut illustrated in the other of its two drive positions;

FIG. 5 is a plan view of the working end of another embodiment of the open-end wrench of the present invention, the pawl being removed to show details of the wrench head configuration;

FIGS. 6 and 7 are respective plan and perspective views of the ratcheting pawl employed with the wrench of FIG. 5;

FIGS. 8 and 9 are both enlarged fragmentary plan views of the working head of the wrench of FIG. 5, each illustrating a nut in a respective one of two drive positions;

FIG. 10 is an enlarged fragmentary plan view of the working head of the wrench of FIG. 5 with the pawl illustrated in position to permit insertion of a nut between the wrench jaws.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now specifically to FIGS. 1 and 2 of the accompanying drawings, there is illustrated an open-end ratchet wrench 10 made of steel or similar structural material and having an handle 11 and a working head 13. Working head 13, as in most open-end wrenches, is substantially wider than handle 11 and is preferably, though not necessarily, somewhat thicker than handle 11. The working head is characterized by a pair of opposed receiving jaws 15 and 17 which are preferably formed integral with handle 11. Jaws 15 and 17 circumscribe a central bore therebetween defined by an interior surface 18 extending between extreme ends of the jaws. Interior surface 18 differs from that of conventional nonratcheting open-end wrenches in that the working surface of the conventional open-end wrench includes two parallel sections extending from the ends of respective receiving jaws inwardly toward the interior of the working head; these sections are then joined by an arcuate section of length dependent upon the size of the nut or bolthead for which the wrench is designed. In FIG. 2, on the other hand, wherein a nut 20 is illustrated in drive position between receiving jaws 15 and 17, it may be seen that the interior surface 18 is segmented to a much greater extent, the details of such segmentation being described fully below. Nut 20 is illustrated as being of hexagonal configuration having apices A, B, C, D, E and F disposed in counterclockwise sequence such that parallel nut sides A-B and D-E are adjacent respective jaws 15 and 17.

The extreme end 19 of jaw 15 is of reduced thickness (thickness meaning the dimension into the plane of the drawing of FIG. 2), thereby providing shoulders 21 and 23 at the junctions between jaw end 19 and the remainder of the working head 13. Jaw end 19 is configured to form a sector of a circle when viewed in plan (i.e., in FIG. 2) wherein the portion thereof comprising a part of the interior surface 18 is the arc of the sector, shoulders 21 and 23 lie on one radius of the sector, and the outer surface of jaw 15 lies on the other radius of the sector.

Defined transversely through the thickness of end 19, proximate the juncture of its two radii, is a pivot hole or bore 25. The latter is preferably a section cutout from the outer surface of jaw 15 adjacent the shoulders 21 and 23, the cutout section being substantially narrower at the outer jaw surface than interiorily thereof. Journaled in hole or bore 25 is a generally cylindrical pin 27 comprising part of a pawl 30, the latter being shown in two positions in FIG. 2. The pawl further comprises a pair of support members 31 and 33 depending from opposite sides of pin 27 along opposite sides of end 19 of jaw 15. A working member 29 extends between support members 31 and 33 at their ends opposite pin 27 and has a flat working surface 35 which is arranged to abut nut surface A-B whenever pawl 30 is positioned such that support members 31 and 33 rest against shoulders 21 and 23 respectively. As illustrated in FIG. 2, working surface 35 of the pawl is substantially larger than the opposite surface of member 29 to permit a relatively large area of the pawl to contact surface A-B of nut 20 whenever the latter is to be driven.

Extending from the rear or closed end of working head 13 through jaw 15 to interior surface 18 is a small-diameter bore or passage, from which a channel extends, the latter being defined in working surface 18 and extending to the terminus of jaw 15. The opposite end of the bore terminates in a cylindrical chamber 37 of substantially greater width than the bore and in which is disposed a helically coiled end of a wire 39, for example, 0.045-inch piano wire. A longitudinal section 41 of wire 39 extends from the coiled end through the bore and along the channel and is soldered or otherwise connected to working member 27 of pawl 30. If the normally relaxed coil is compressed in chamber 37, longitudinal section 41 of the wire forces pawl 30 away from shoulders 21 and 23 and toward the extreme end of jaw 15. The pawl thus pivots about pivot hole 25 to swing working member 29 clear of the wrench working area and thus permit the wrench jaws to be inserted over the head of nut 20. To this end, the portion of working surface 18 comprising part of jaw end 19 is contoured to permit working member 29 to completely clear the working area of the wrench (as illustrated by the dashed line position of pawl 30 in FIG. 2). When the pawl is so pivoted, longitudinal section 41 of wire 39 rides in the channel defined in interior surface 18.

Segmentation of interior surface 18 of the wrench is accomplished with an eye toward optimizing two considerations, namely: maximization of torque applied to nut 20 during drive operation; and achieving the smoothest possible ratcheting action. As to the first consideration, it can be shown by mathematical analysis that an interior wrench surface configured to provide a three-point drive capability places significantly less stress on the wrench jaws than does an interior wrench surface configured to provide a two-point drive capability. Three-point drive operation is achieved for wrench 10 by means of

a. working surface 35 of pawl 30;

b. segment 43 of interior surface 18, disposed at the extreme end of jaw 17 and configured to abut approximately one-quarter of nut side E-F adjacent apex E; and

c. segment 45 of interior surface 18, configured to abut approximately one-quarter of nut surface C-D adjacent apex C.

It is to be noted that the three contact points (working surface 35 and segments 43 and 45) are spaced by approximately 120.degree., thereby providing wrench 10 with the maximum possible torque transfer capability for a three-point drive wrench.

Viewing wrench 10 in FIG. 2, it will now be appreciated that by rotating the handle 11 clockwise, the three 120.degree. spaced drive points will transmit clockwise torque to nut 20 and the latter may be tightened.

To achieve a ratcheting operation for wrench 10 as viewed in FIG. 2 the handle 11 must be rotated counterclockwise about either point X, at the counterclockwise end of surface segment 43, or point Y, at the counterclockwise end of surface segment 45. To maximize ratcheting smoothness, as much of interior surface 18 as possible should contact nut 20 during the ratcheting operation. This provides a guide for the wrench and minimizes the possibility of the wrench and nut becoming disengaged. However, if too much of interior surface 18 contacts nut 20 during the ratcheting operation, there will be insufficient clearance for the various apices of the nut and ratcheting will not be possible. I have found that by providing an additional segment 47 of interior surface 18 adjacent but not abutting the nut, the nut is provided with an additional guide surface which significantly improves ratcheting smoothness. More particularly, segment 47 is disposed adjacent but not abutting the end of nut side D-E at a location approximately 60.degree. displaced from each of segments 43 and 45. I have found that when, during ratcheting, there is relative rotation between the wrench and nut about either of points X and Y, the apices of the nut sweep out an area which does not overlap segment 47, and consequently this segment does not interfere with the ratcheting operation. Moreover, in the drive operation, should there be any flexure of the wrench jaws, segment 47 serves as a backup drive point and reduces the stresses on the wrench.

The remainder of the contour of interior surface 18, with one exception, is made to conform to the area swept by the apices of nut 20 when there is relative rotation between the nut and wrench about points X and Y. In this manner smooth ratcheting action is assured because alignment of the wrench and nut can be maintained. This is very important in the case of cocked wrenches where handle 11 and head 13 are not coplanar. The one exception mentioned about concerns the portion of surface 18 in the vicinity of pawl 30. In the latter case the contour of the interior surface of the wrench must be made to conform to the clearance requirements of the pawl.

Viewing the ratcheting operation in FIG. 2, upon counterclockwise rotation of the wrench handle 11 about either of points X or Y, the wrench head 13 tends to rotate counterclockwise relative to nut 20. Nut side A-B tends to push the pawl 30 toward the end of jaw 15 until such time as apex B is disposed clockwise of the pawl. At this time the pawl is returned into abutting relation with shoulders 21 and 23 and the nut is in a position to be driven; in this new position however the nut is disposed 60.degree. clockwise from the position illustrated in FIG. 2.

It is pertinent to pause here and consider the significance of the embodiment described above. For one thing the position of a body confined to a plane is determined by three points because there are three degrees of freedom in that plane (two translational and one rotational). By providing the three symmetrically disposed drive points, approximately 120.degree. apart, I have provided the minimum number of drive points to prevent the wrench from slipping off the nut during the drive operation. By making only one of these drive points movable and having the other two fixed, I have also provided ratcheting with only one ratcheting element. I have thus provided an open-end ratcheting wrench which holds the nut in the optimum manner in view of the number of possible degrees of freedom of motion and at the same time minimizing the number of moving parts that permit ratcheting. Important in the ratcheting scheme is the fact that the surfaces and apices of the nut itself are employed to maintain wrench and nut alignment.

The positioning of pawl 30 on receiving jaw 15 bears some consideration at this point. For one thing, it is noted that the pawl pivot point (bore 25) is further back toward wrench handle 11 than is drive surface 53, so that in the drive position support members 31 and 33, which abut shoulders 21 and 23 respectively, are not perpendicular to nut surface A-B. Similarly, of course, shoulders 31 and 33 are not perpendicular to nut surface A-B. There are reasons for so placing the pivot point; more particularly the further back (i.e., closer to the handle 11) the pivot point is moved the smaller the angle through which pawl 30 must move in order to provide clearance for apex B during ratcheting. Also aiding to decrease the ratcheting angle for pawl 30 is the fact that the pawl pivot point (bore 25) is proximate the outer surface of jaw 15 and as far away from working member 29 as possible. There are limitations to how far back the pivot may be moved. For example if the pivot point is moved too far back toward handle 11, surface 35 will tend to slip off nut surface A-B during drive operation. On the other hand if the pivot point is moved too far forward toward the open end of the wrench, the pawl might tend to bind during ratcheting. I have found that the angle between nut surface A-B and shoulders 21 and 23 is optimized between 70.degree. and 80.degree. for most purposes. For extremely clean smooth oily surfaces an angle greater than 80.degree., but less than 90.degree., may be used. For extremely dirty, dry or rough surfaces an angle of 70.degree. may be preferable to insure proper ratcheting.

Another important feature of the open-end ratchet wrench of FIGS. 1 and 2 is the fact that pawl 30 is placed under compression only when nut 20 is tightened. It is important for the life and reliability of the wrench that pawl 30 does not experience either tension or torsion stresses during drive operation because the latter stresses require substantially less applied force to produce rupture of the pawl than does compressive stress.

In summary, some of the advantages of wrench 10 may be enumerated as follows:

a. It grips the nut during drive operation at three drive points spaced approximately 120.degree. apart, thereby placing substantially less stress on the wrench jaws than is the case for the conventional two-point drive in conventional open-end wrenches;

b. It requires only a single ratcheting element;

c. The pawl experiences compressive forces only during tightening operation;

d. It occupies no more space than that occupied by a conventional open-end wrench;

e. Manufacture of the wrench is extremely simple because it can be made with only three parts namely the wrench body including handle 11 and working head 13, pawl 30, and the retention spring 39.

It should be pointed out that the pawl 30 may be arranged to contact surface A-B of the nut closer to apex A than is illustrated, whereby even less stress would be experienced by the wrench jaws during tightening; however, this makes the wrench more cumbersome during ratcheting and would require enlarging jaw 15 somewhat.

For some applications it is desirable to have an open-end ratchet wrench which requires no special actuator to permit the wrench jaws to be inserted over the nut head from the side. In other applications it is desirable that the nut be capable of being driven from more than one position relative to the wrench jaws; this means that the minimum ratcheting angle for the hexagonal nut shown in FIG. 2 should be less than 60.degree.. An embodiment of the present invention which encompasses both of these features is illustrated in FIGS. 3 and 4 of the accompanying drawings and employs two pawls of the type described above, arranged so that each is in position to drive the nut in a respective one of two drive positions of the nut relative to the wrench jaws. More particularly, the open-end ratchet wrench 50 of FIGS. 3 and 4 includes a handle 51 and a working head 53, the latter being characterized by opposed receiving jaws 55 and 57. The receiving jaws circumscribe a central bore defined by interior surface 59 extending interiorily of working head 53 between extremities of jaws 55 and 57. Interior surface 59 is contoured to permit nut 60 to be fixedly positioned thereagainst in two positions, namely the position illustrated in FIG. 3 wherein parallel nut surfaces A-B and D-E are substantially parallel to the direction in which receiving jaws 75 and 57 extend, and the position illustrated in FIG. 4 wherein nut 60 is rotated 30.degree. counterclockwise relative to its position in FIG. 3. Interior surface 59, in order to accommodate the nut in both of these positions, is segmented to a greater degree than is interior surface 19 in FIG. 2 as described in detail below.

The extreme end 63 of receiving jaw 55 is of substantially reduced thickness relative to the remaining portion of working head 53, and is separated therefrom by a pair of shoulders 65, only one of which is illustrated and which are similar to shoulders 21 and 23 in FIG. 2. A pawl 70, substantially identical in configuration to pawl 30 of FIG. 2, is pivotally engaged to end portion 63 of receiving jaw 55 in the same manner as pawl 30 is engaged to end 19 of jaw 15 in FIG. 2. Pawl 70 can thus be pivoted so as to be displaced along the segment of interior surface 59 which is part of the end portion 63 of jaw 55. The pawl may thus be pushed away from interference with nut 60 during ratcheting operation. A generally cylindrical compartment 71 is located in jaw 55, closer to handle 51 than to end 63 of jaw 55. A narrow passage 73 extends coaxially from chamber 71 and terminates at working surface 59 slightly rearward (to the left in FIG. 3) of end portion 63. A channel 75 is defined in interior surface 59, extending from the terminus of passage 73 to the end of jaw 55.

A compression spring 77 is disposed in chamber 71 and has secured thereto flexible wire element 79 which is secured to pawl 70 in a manner similar to that by which wire section 41 is secured to pawl 30 in FIG. 2. Spring 77 thus normally retracts pawl 70 to the position shown in FIGS. 3 and 4 whereby the pawl abuts shoulders 65. When biased against shoulders 65, pawl 70 has its working surface 74 abutting nut surface A-B near apex A when nut 60 is positioned as in FIG. 3.

A somewhat similar pawl arrangement is provided at jaw 57, however not at the extreme end of jaw 57; rather, the section 81 of reduced thickness at jaw 57 is isolated between the extreme end of jaw 57 and the remainder of the working head 53. A pawl 80 is configured substantially the same as pawl 70 and is pivotable about a bore 83 formed transversely through jaw 57 at the forwardmost (to the right in FIG. 3) portion of section 81 of jaw 77 and substantially adjacent the outer surface of the jaw. A pair of shoulders 85 define the juncture between the extreme end portion of jaw 77 and the jaw section 81 of reduced thickness. Pawl 80 is biased against shoulders 85 by a compression spring 87 disposed in a chamber 89 in working jaw 57 rearwardly of section 81.

Pawl 80 has its working surface 95 positioned in abutting relationship with side D-E near apex D of nut 60 when the latter is oriented as illustrated in FIG. 4.

The contour of interior surface 59 is arranged so that there are at least two drive points for nut 60 in each of its two drive positions, yet clearance for pawls 70 and 80 is provided so that they do not interfere with the ratcheting operation. More specifically, surface 59 is provided with a segment 101 which abuts side D-E near apex D of nut 60 (when the latter is positioned as in FIG. 3) at a point displaced from working surface 74 of pawl 70 by approximately 180.degree.. To provide the second drive point when nut 60 is positioned as illustrated in FIG. 4, interior surface 59 projects inwardly to contact side A-B of nut 60 near apex A. This segment designated 103 in the drawings, provides contact with side A-B across the thickness of the interior surface 59 of the wrench. Contact segment 103 is spaced approximately 180.degree. from working surface 95 of pawl 80 when the latter is in its drive position.

The portion of working surface 59 extending between contact segments 103 and 101 is divided into five toothlike projections, spaced by 30.degree., the spaces between alternate projections being arranged as illustrated to receive the apices of nut 60 in each of its two drive positions.

The portion of interior surface 59 immediately clockwise of contact segment 103 and counterclockwise of jaw end 63 is contoured to provide clearance for the apices of nut 60 during ratcheting (counterclockwise rotation of wrench 50) irrespective of which projection the wrench is pivoted about. The segment of interior surface 59 which coextends with end 63 of jaw 55 is contoured to permit clearance for pawl 70 during ratcheting so that the pawl does not interfere with the apices of the nut. Likewise the segment of surface 59 which is counterclockwise of contact segment 101 is contoured to permit clearance for the nut apices during ratcheting, and is also recessed at 105 to receive pawl 80 during ratcheting.

Operation of the wrench, with nut 60 positioned as in FIG. 3, is as follows: to tighten the nut the wrench handle is rotated clockwise whereupon working surface 74 of pawl 70 and contact segment 101 of interior surface 59 provide the primary drive points. For ratcheting operation the handle is rotated counterclockwise, causing relative motion between working surface 59 and nut 20. More specifically, as the relative rotation between nut and wrench progresses, nut side D-E pushes pawl 80 into recess 105. After 30.degree. of ratcheting the nut will be in a drive position similar to that of FIG. 4 and the pawls will return to their spring-loaded position.

When the nut is positioned as in FIG. 4, the following operation is possible: When the wrench is rotated clockwise, nut 60 is driven primarily by contact segment 103 and working surface 95 of pawl 80. In the ratcheting mode, nut side A-F displaces pawl 70 and neither pawl interferes with the ratcheting operation.

Important to note with regard to wrench 50 is that the wrench may be inserted over nut 60 from the side, without actuating either pawl, so that the nut is positioned as illustrated in FIG. 3. This is made possible as shown in FIG. 3 by the fact that the pawls 70, 80, when in their normal positions, are spaced by a distance which is slightly greater than the distance between parallel sides of nut 60. This distance between the pawls can in fact be smaller than this because, upon insertion of the nut, pawl 80 will be pushed into recess 105 and thereby provide sufficient clearance to complete the insertion.

The embodiment illustrated in FIGS. 3 and 4, as described above, does in fact permit nut insertion without a special actuator and also permits 30.degree. ratcheting. However it achieves these features with two ratcheting elements and by utilizing only two primary drive points. The embodiment illustrated in FIGS. 5-10, while requiring an actuator for nut insertion, has a 30.degree. ratcheting capability and three-point drive with only one ratcheting element. More specifically, and referring now to FIGS. 5-10 of the accompanying drawings, a wrench 110 comprises a handle 111 and working head 113. The working head comprises two receiving jaws 115 and 117 which circumscribe a working area therebetween, bounded by interior surface 119 extending between extremities of the two jaws.

The forwardmost (to the right in FIG. 5) section 121 of jaw 115 is of reduced thickness from that of the rest of working head 113, there being a pair of shoulders 123 (only one illustrated) on either side of section 121 defining the juncture between that section and the rest of the working head. Section 121 is provided with a slot 125 disposed in accordance with considerations to be described in detail below.

A pawl member 130 includes a pair of opposed sidewalls 131, 132 each having one edge 133 configured to substantially match the contour of shoulders 123. A second edge 134 of sidewalls 131, 132 intersects edge 133 at an apex point and is configured to substantially match the configuration of the outer edge 129 of jaw section 121; however, it should be noted that edge 134 is longer than edge 129 so that the former may be viewed as an extended version of the latter. A third edge 136 of sidewalls 131 and 132 joins edges 133 and 134 and is configured in accordance with considerations to be described below.

Joining sidewalls 131 and 132 in precise alignment and extending therebetween are spaced working members 135 and 137, each having a working surface which is coplanar with a respective portion of edge 136 of sidewalls 131, 132. The spacing between sidewalls 131, 132 afforded by working members 135 and 137 is sufficient to permit section 121 of wrench jaw 115 to be inserted between the pawl sidewalls so that edges 133 and 134 of the sidewalls are in precise registration with shoulders 123 and surface 129 respectively of the wrench.

The pawl 130 is secured to the wrench body by means of a pin 143 extending through slot 125 and through aligned transverse holes 141, 142 defined through sidewalls 131, 132 respectively. Pin 143, combined with slot 125, provides pawl 130 with the capability of both rotational (about the pin) and translational (along the slot) motion relative to wrench jaw 115.

A compression spring 145, inserted in a compartment 147 provided in handle 111, has extending therefrom a wire 149. The latter passes through a passage 151 which is defined through the wrench body and terminates at that portion of interior surface 119 which is part of jaw section 121. The end of wire 149 which extends through passage 151 terminates in a loop 153 which is of sufficiently large diameter to prevent the loop from being drawn into passage 149. Loop 153 receives pin 155 which also passes through aligned transverse holes 157, 159 defined through sidewalls 131, 132 respectively. Holes 157, 159 are slightly more rearward and closer to the axis of handle 111 than are holes 141, 142.

An actuator arm 161 is pivotally mounted at one end on handle 111 at pivot point 163. Secured to actuator arm 161 at a point displaced from pivot point 163 is a linkage member 165 which connects the pivot arm to spring 145. When actuator arm 161 is in the position indicated by the solid lines in FIG. 5, spring 145 is placed in tension so that loop 153 is retracted against interior surface 119. In this condition the pawl 130 is in its drive position relative to the wrench head as illustrated in FIGS. 8 and 9.

If actuator arm 161 is now pivoted counterclockwise to the position illustrated by the dashed lines in FIG. 5, spring 145 is compressed and loop 153 is extended to its position illustrated by dashed lines in FIG. 5. In this condition pawl 130 is extended to its open position as illustrated in FIG. 10.

The contour of edge 135 of pawl 130 includes a first surface S1 which is coextensive with a portion of the bottom edge of forward working member 135 and therefore extends rearwardly from pawl edge 134. With the pawl in its drive position and a nut 100, having apices A, B, C, D, E and F, arranged in counterclockwise sequence, positioned as illustrated in FIG. 8, surface S1 is parallel to and abuts nut side A-B adjacent apex B. A second surface S2, coextensive with a portion of the bottom edge of rearward working member 137, is coplanar with surface S1 and abuts nut surface A-B adjacent apex A. Between surfaces A and B edge 136 forms a recess comprising two edge sections intersecting at an angle of 120.degree.. This recess is adapted to receive an apex (for example, apex A) of nut 100 when the latter is positioned in its second drive position as illustrated in FIG. 9. Rearwardly of surface S2 the pawl edge 136 is configured to avoid interference with the area of the path swept by nut 100 during ratcheting about even the most disadvantageous pivot point, which, it turns out, is point Z, the terminus of interior surface 119 at the end of jaw 117.

Interior surface 119, in its portion coextensive with jaw 117, comprises a series of five toothlike projections, including that whose apex is point Z, spaced 30.degree. apart. The recessions between these projections are formed by two surfaces, intersecting at a 120.degree. angle, so that each sequence of alternate recessions receives respective sequential apices of nut 100 in a respective one of the wrench drive positions.

In the vicinity of jaw 115, interior surface 119 is contoured to permit clearance between jaw section 121 and rearward working member 137. In this regard, the uppermost portion of the contour of interior surface 119 is seen to be curved so that the pawl 130 may be moved from its drive position (FIGS. 8, 9) to its open position without frictional engagement between the upper surface of rearward working member 137 and the interior wrench surface 119. Proceeding clockwise from this uppermost portion of its contour, surface 119 curves back down toward forward working member 135 so as to contact the upper surface of the latter at region P. Still proceeding clockwise, surface 119 curves up and away from region P and working member 135 until terminating at the end of jaw 115.

The contours of interior surface 119 and the upper surface of working member 135 at their region of contact are of crucial importance. This is best appreciated from an operational description of the wrench. More specifically, and referring to FIG. 8, there are three driving points for nut 100 with the nut in the illustrated position. These are:

a. Surface S1 of the pawl which contacts nut side A-B adjacent apex B;

b. Surface segment 171, a defining surface of one of the toothlike projections from interior surface 119, which abuts nut side E-F adjacent apex F at a point displaced approximately 120.degree. counterclockwise from drive point (a) above; and

c. Surface segment 173, the segment extending immediately clockwise from point Z, which abuts nut side C-D adjacent apex D at a point approximately 120.degree. displaced from each of drive points (a) and (b) above.

When the wrench is rotated clockwise from its position in FIG. 8, a clockwise torque is applied to the nut by surface segments 171 and 173 from jaw 117. The torque applied by surface S1 is received from jaw 115 via jaw section 121 and forward working member 135. Thus it is region P at which jaw 115 transmits forces to pawl 130 for this position of nut 100. It is important that the upper surface of member 135 be contoured so that it does not slide to the right relative to region P; for if such were to occur, the pawl would move relative to nut 100 and would be unable to drive the nut.

Let us now examine the ratchet operation, initiated with the nut positioned as in FIG. 8. As the wrench is rotated counterclockwise, nut side A-B at apex A tends to push working member 137 upward and to the right. Upward movement is restricted somewhat but not entirely by pin 143 abutting the upper wall of slot 125. Upward movement of member 135 is restricted by contact region P. As a consequence the net movement is part rotational, part translational whereby the upper surface of forward working member 135 rides clockwise along the contour of interior surface 119 and the upper surface of rearward working member 137 moves clockwise toward the uppermost point in the contour of interior surface 119. This motion continues, with nut apex A progressing clockwise along surface S2 until it reaches the clockwise end thereof, at which time the pawl is retracted by spring 147 and apex A resides in the recess defined in edge surface 136 between surfaces S1 and S2. This new position of the nut corresponds to the second drive position illustrated in FIG. 9.

An important aspect of the above-described ratcheting sequence is that the rearward section of the upper surface of forward working member 135 must be contoured to permit that member to slide clockwise along interior surface 119. It is noted that it was precisely this motion which must be prevented during a drive operation, as discussed above. Consequently the relative contours of the upper surface of member 135 and the interior surface 119 to the right of region P must be optimized against these counterbalancing considerations. Obviously the coefficient of friction of the material employed comes into play here, so that the optimum angle will vary. In general, the following analysis will be helpful: If we imagine a circle, centered at point Z (the worst case pivot point) and having a radius extending to region P, surface 119 must make a positive angle with the tangent to that circle at P in order to prevent binding between member 135 and the wrench during ratcheting; the greater this angle, the less the tendency to bind; however if this angle is too great, member 135 will slip during drive operation.

Referring now specifically to FIG. 9 and the position of the nut therein, there are two primary drive points, namely:

a. Surface 177 in the recess of pawl edge 136 which abuts nut side A-F adjacent apex A; and

b. Surface 179, comprising the edge of one of the toothlike projections in surface 119 disposed 30.degree. counterclockwise of surface 173, which abuts nut surface C-D adjacent apex D at a point displaced approximately 180.degree. from drive point (a).

In this case, surface 179 receives its driving force directly from jaw 117 of which it is a part; surface 177 receives the force transmitted to pawl 130 by jaw 115 at shoulder 123.

To ratchet from the position illustrated in FIG. 9, the wrench is again rotated counterclockwise. In this case apex A of the nut tends to push forward working member 135 to the right of jaw section 121 and at the same time slides clockwise along the recess in pawl edge surface 136. Upon clearing the recess apex A no longer pushes the pawl, and the latter is retracted back towards the drive position illustrated in FIG. 8. Here, the major consideration to be kept in mind is that pawl edges 133 must not bind against shoulders 123 and sufficient clearance must be provided in this region.

One consideration which bears mentioning is that the retraction force exerted by spring 145 on the pawl should be directed substantially in the direction of slot 125 so that the spring does not exert a rotational force on the pawl. Such rotational force could cause the pawl to bind on the wrench jaw in region P. In other words if the retracting force of the spring tended to rotate the pawl clockwise, the angle between surface 119 at point P and the tangent to the imaginary circle, centered at point Z and extending to P, would be reduced.

On the other hand, the extension force applied by the spring when placing the pawl in its open position should have a slight counterclockwise component in order to initially raise the rear end and lower the forward end of the pawl. This permits member 135 to readily clear the wrench jaw.

The direction of the forces applied by spring 145 can be readily controlled by properly orienting passage 151 relative to slot 125.

While I have described and illustrated specific embodiments of my invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.

Claims

I claim:

1. An open-end ratchet wrench for driving a polygonal-shaped element of specified size such as a nut, bolt, and the like when rotated, said wrench comprising: a handle having a working head secured thereto, said working head comprising a pair of receiving jaws circumscribing a work area therebetween for receiving said polygonal-shaped element, said work area being defined by an interior surface extending between respective extremes of said receiving jaws; a first pawl having a working surface and mounted on said working head such that said pawl is movable relative to one of said jaws; means for defining a first limit position of said pawl wherein said working surface extends into said work area; means for biasing said pawl toward said first limit position; means for defining a second limit position of said pawl wherein said pawl is sufficiently retracted from said work area to permit rotational motion between said work head and said polygonal-shaped element when said wrench is rotated about the latter in a first direction; and wherein said interior surface is contoured to provide two projections which combine with said working surface when said pawl is in said first limit position to provide three 120.degree. spaced drive points which engage and rotate said polygonal-shaped element when the latter has a predetermined orientation within said work area and said wrench is rotated in a second direction opposite said first direction.

2. The wrench according to claim 1 wherein said one of said jaws has an end section of reduced thickness so as to define a pair of shoulders on opposite sides of said end section at the junction between said end section and the remainder of said one jaw; and wherein said pawl comprises a working member of which said working surface is a part and which is disposed adjacent said interior surface at said one jaw, a pivot pin extending between a transverse bore defined through said end section of said one jaw for pivotally mounting said pawl to said jaw, and a pair of support members extending from said pivot pin along respective sides of said end section of said first member to said working member, said transverse bore being disposed such that said support members abut respective ones of said shoulders when said pawl is in said first limit position.

3. The wrench according to claim 2 wherein said transverse bore is located closer to said handle than is said working surface when said pawl is in said first limit position, whereby said shoulders subtend an angle of less than 90.degree. with the surface of said element which is engaged by said working surface.

4. The wrench according to claim 3 wherein said angle is approximately 60.degree..

5. The wrench according to claim 1 wherein at least part of said interior surface is contoured to conform with the area swept by said polygonal-shaped element during ratcheting about a specified point.

6. The wrench according to claim 5 wherein said one of said jaws has an end section of reduced thickness and wherein said pawl is bifurcated to fit over said end section without extending beyond the exterior confines of said working head.

7. The wrench according to claim 6 wherein said pawl is mounted to said end section for both rotational and translational motion relative thereto, said pawl having a second working surface which combines with a third projection from said interior surface when said pawl is in said first limit position to provide two 180.degree. spaced drive points which rotate said element when the latter has a further predetermined orientation within said work area and said wrench is rotated in said second direction.

8. The wrench according to claim 7 wherein said interior surface in the vicinity of said end section of said one jaw is contoured to force said pawl into a combined rotational and translational motion relative to said end section when said wrench is rotated in said first direction.

9. The wrench according to claim 1 wherein the angle made by said working surface in said first limit position with the tangent of a circle centered at the apex of the other of said receiving jaws and having a radius equal to the distance between said apex and said working surface is an acute angle which is sufficiently small that said pawl does not slip from said first limit position when said wrench is rotated in said second direction and yet sufficiently large as to prevent binding of said pawl against said one jaw when said wrench is rotated in said second direction.

10. The wrench according to claim 1 further comprising: only one additional pawl having a working surface and mounted on the other of said jaws for relative motion thereto; means for defining a first limit position for said additional pawl wherein said working surface of said additional pawl extends into said work area; means for biasing said additional pawl toward said first limit position; means for defining a second limit position for said additional pawl wherein it is retracted into said interior surface at said other jaw; said polygonal-shaped element having a second orientation in said work area in which it may be driven by two 180.degree. spaced drive points comprising said working surface of said additional pawl in its first limit position and a projection from said interior surface, the opening at the open end of said wrench being sufficiently large when both pawls are in their first limit position to permit said working head to be inserted on said polygonal-shaped element in the plane of the latter.

11. The wrench according to claim 1 wherein said pawl has a work area defining surface, said latter surface having a triangular-shaped depression lying between two coplanar flat surfaces, said surfaces arranged such that at least one of said coplanar surfaces contacts said polygonal-shaped element when it has said predetermined orientation within said work area and one of said surfaces defining said triangular-shaped depression in said pawl engages said polygonal-shaped element when it has a second orientation within said work area.