Anti-kick saw bar

Abstract

 An anchor in a chain saw guide bar digs into the sidewall of a kerf as soon as kickback begins, to stop kickback of the guide bar while it is in the kerf. The anchor does this with a laterally projecting, impaling fluke mounted to the bar and biased towards its projecting position through a torsion spring contained completely within the bar. Bends in the torsion spring about longitudinal axes increase the bias angle of the fluke relative the kerf. Bumper faces of the fluke permit entrance of the fluke into the kerf and movement within the kerf in the longitudinal and downward directions by the fluke displacing towards the bar. A stop pivot adjacent the side of the guide bar opposite that from which the fluke extends, engages the fluke, prevents downward deflection of the fluke when it experiences kickback forces, and provides an off-center pivot for the spring to force it to resist deflection by torsion. A lateral limit stop applies a preload torque to the fluke to torsionally load the spring so that the spring urges the fluke outwardly. A retractor cam adjacent the fluke, when operated, draws the fluke within the guide bar for unusual cuts.

Description

Background of the Invention

[0001] The present invention relates to chain saws and, in particular, to a chain saw guide bar and anchor that prevents kickback.

[0002] Chain saws operated by one person were developed around the time of World War II and have become very versatile and popular tools. Examples are described in U.S. Patents 2,508,784 and 2,622,636, earlier patents of mine. A chain saw has a flat saw guide bar that provides a track around its perimeter for a power driven cutting chain and bearing support for the chain. The bar extends from the chain's power source and the end where an operator holds the saw to a nose at a free end of the bar. The chain has cutter links with cutters for cutting into the work. These links also have depth gauges preceding the cutters that limit the bite of the cutters to a prescribed depth and heels trailing the cutters that limit the bite of the cutters as they go around the nose. Drive links on the chain links track in a continuous slot in the perimeter of the bar to keep the chain on the bar. The nose end of the bar has no constraint. The chain travels unshielded over the top, nose and bottom of the bar.

[0003] The saw guide bar has evolved from the relatively thick to the thin bars of today. Today's saw guide bars are usually about 0.150 inches thick. This evolution resulted from the advantages of lightness and lower power requirements in thin saw bars. The chain of today's saws has a set of about 0.03 inches from each side of the saw bar so that the width of a cut (called a "kerf") is about 0.21 to about 0.25 inches.

[0004] An operator makes a cut by contacting the work with the moving chain and permitting the chain to cut into the work. There are different types of cuts, among them: boring, bucking, and falling. Boring refers to a cut made at the nose of the guide bar by pushing the guide bar and chain into the work nose end first. Bucking refers to a cut made by cutting down into the work with the plane of the guide bar generally vertical with respect to the ground and with the work lying horizontal with respect to the ground. Falling refers to falling a substantially upstanding tree where cuts are usually made horizontal to the ground. With the path of the cutting chain considered to be in the plane of the guide bar, the following conventions will be observed in this specification: "length" or "longitudinal" refers to the direction or dimension in the plane c: the guide bar along a line from the nose to the power source; "width" or "short transverse" refers to the direction perpendicular to the plane of the guide bar; "height", "vertical" or "long transverse" refers to the dimension or direction in the plane of the guide bar but perpendicular to the length. Thus, length, width, and height are with reference to the guide bar and not necessarily the observer or ground.

[0005] One-person-operated chain saws became a serious safety hazard to their operators as soon as the saws came into use because of "kickback." Kickback refers to rotational movement of the saw bar and cutting chain out of the kerf and towards an operator as a result of the moving chain along the nose of the bar contacting increased resistance, such as a stump, or a limb on the other side of a log from an operator, and climbing out of the kerf. Kickback often occurs when using a saw bar shorter than the diameter of the log being cut. With such a saw bar, the nose of the bar enters the log, producing a transverse kerf wall at the nose end of the bar. With a change in the position of the saw bar, the chain going around the nose can dig into this wall, causing the chain to climb up the wall, kicking the saw bar and chain back at the operator's head. The same thing happens when falling a tree, except the bar and chain are more apt to strike an operator's legs or body than the head. Kickback often occurs very quickly; so quickly that the cutting chain and saw bar can kick back and be at an operator's head before the operator realizes that kickback is occuring.

[0006] In greater detail, in kickback, the chain at the nose of the guide bar encounters increased resistance and tends to stop, but the chain under power continues to try to move with respect to the bar: the movement that occurs when the bar rotates backward is kickback. In a kickback, instead of the chain moving freely with respect to the saw bar, work, and operator, the chain tends to stop with respect to the work and operator in favor of the saw bar moving towards the operator. In other words, as the chain slows upon encountering increased resistance, the relative motion between the chain and the guide bar continues as before but now with the guide bar moving with respect to the operator in a rotational arc at a velocity as high as the surface speed of the saw chain with respect to the bar. In an analogy, a runner is the chain and the ladder is the resistance. The runner runs across the ground like the chain cutting through wood until meeting the ladder. But upon meeting the ladder, the runner must climb up it and cannot run across the ground, just as the nose of the chain must climb up a kerf wall when meeting sufficient resistance.

[0007] The problem of kickback has been addressed since chain saws came into existence without a good solution. One popular proposed solution reduces the radius at the nose of the bar; this hurts a saw's performance because the chain cutters going around the nose do not cut as much wood because their cutting edges move inwardly towards the path of the depth gauges. The use of guide bars with small radius noses does reduce kickback but does not eliminate it, and it reduces the efficiency of the saw. A second and similar approach to the problem modifies the chain to reduce its cutting ability around the nose of the bar; this approach has the same problems as the first one.

[0008] A third approach uses a chain brake. A chain brake stops a chain's rotation with respect to the bar upon sensing a kickback. But stopping the chain's rotation does not stop the motion of the bar and chain from continuing on back until it strikes an operator. _Moreover,a chain brake is a complex of levers, pivots, and springs that can easily malfunction because of environmental pitch, sawdust, dirt, grit, and debris collecting in the working parts.

[0009] Regardless of the approach, the serious safety problem of kickback has not been solved. According to one authoritative source, 22,000 injuries from kickback from chain saws occurred in 1982. Obviously, there is a great need for an effective anti-kick saw bar that positively prevents kickback while the saw bar is in the work. There is also a great need for an anti-kickback saw bar that is effective without compromising the cutting qualities otherwise available in a chain saw.

Summary of the Invention

[0010] The present invention provides an anti-kickback anchor in combination with a chain saw guide bar that positively prevents kickback while the bar is in the work with the anchor in position to engage the wall of a kerf and that permits the guide bar and chain design to be unaffected by kickback considerations.

[0011] In one form, the present invention includes an anti-kickback anchor for attachment to a chain saw guide bar. The anchor has a fluke for extending laterally from one side of the bar. The fluke has an upper edge for digging into the sidewall of the kerf at the outset of kickback. Means resiliently mount the fluke to the guide bar so that the fluke has this lateral extension but such that the fluke moves inwardly towards the plane of the guide bar in response to the wall of the kerf acting on it during normal motions -of the guide bar, during the making of a cut, inserting the guide bar into the kerf, and withdrawing the guide bar from the kerf. Bumper deflector means on the fluke bump against kerf walls to deflect the fluke inwardly during such motions.

[0012] In a more particular form of the present invention, the resilient mounting means of the anchor includes a torsion spring for mounting that lies completely within the confines of the guide bar. The fluke mounts at a free end of this torsion spring. The spring can easily twist in one direction to bring the fluke toward the plane of the bar in response to the kerf wall pressing on it, but the spring cannot easily twist in the other direction away from the plane of the bar because the kerf wall restrains the fluke. Spring pressure on the fluke and its angle with respect to the kerf wall digs the fluke into the kerf wall during kickback. Preferably, a stop in the form of a base pivot stiffens the fluke against vertical and lateral deflection. A lateral limit stop keeps the fluke under torsion at a maximum angle away from the plane of the saw bar. The lateral limit stop and pivot may be in a pocket defined by a shoulder that keeps the torsion spring from bending down or bending laterally away from the fluke while permitting the fluke to twist about the pivot toward the plane of bar in response to modest forces on it from the kerf wall. In other words, the base pivot forces the spring to rotate in torsion in response to transverse forces on the fluke towards the plane of the bar instead of bending of the entire spring about a vertical axis in the plane of the bar.

[0013] In the particular form of the invention, the spring is tall and thin so that it resists only modestly torsional displacement inwardly toward the plane of the bar in response to the benign forces associated with normal cuts, while it strongly resists bending in the plane of the bar from downward forces occurring during kickback. Ease in twisting can be enhanced by the spring being capable of some bending at right angles to the plane of the bar about axes in the plane of the bar, achieved with a spring with a mid-portion having a serpentine shape. An example of a serpentine-shaped spring is a spring having rectilinear undulations, such as generally square undulations, that, in cross-section at right angles to the plane of the bar, has an elevational dimension substantially greater than its horizontal or width dimension. Vertical legs of the undulations bend and increase the spring's flexibility. The fluke has deflector bumper faces for permitting the fluke to downwardly or longitudinally enter the top or axial ends of the kerf, contacting the bumpers and displacing the fluke towards the plane of the bar. Preferably, the torsion spring mounts to the guide bar at a base of the anchor that in turn mounts in a pocket in the bar.

[0014] In addition, the mounting means of the anchor includes means for steeply inclining the fluke relative to the plane of the guide bar plane. In the preferred form, the mounting means includes at least one bend outward from said plane of said guide bar, to angle the fluke a distance substantially equal to about the thickness of the chain saw guide bar, e.g., 40-50 degrees relative the plane of the guide bar. In the preferred form a first bend about a first longitudinal chain saw bar axis extends the foot portion, as earlier described, towards a second side of the guide bar opposite the impaling edge and is angled from about 10 to about ₂₅ degrees relative to the plane of the guide bar. The first bend may be bent in excess of this angle from about 4 to about 6 degrees. A second bend in the anti-kickback anchor about a second longitudinal chain saw guide bar axis extends the fluke outward from the plane of said foot portion to project from a side opposite the foot portion beyond the plane of the first side of the guide bar, in the preferred form from about 25 to about 35 degrees relative to the plane of the foot portion, i.e. a distance substantially equal to about the thickness of the chain saw guide bar.

[0015] The shape of the fluke is very important. The fluke must be able to enter a kerf and move freely in it without much resistance during normal saw bar motions.

[0016] The fluke, extendible upward and outward from the chain saw guide bar includes a bumper deflector means for allowing only longitudinal and downward guide bar motion and an arcuate impaling edge for precluding any substantial upward motion of said chain saw guide bar. More specifically, the bumper deflector means further includes sloping faces in the downward, forward and rearward directions relative to the chain saw guide bar. A first face, facing downward relative to the chain saw guide bar, extends upwards and outwards from the mounting means to the apex. The first bumper face forces the fluke inward when the bar moves downwardly within or to enter the kerf. A second or forward bumper face, folded towards the plane of the chain saw guide bar from the first bumper face, extends upward from the first bumper face, to define a first portion of the impaling edge. A third or rearward bumper face, folded towards the plane of the guide bar from the first bumper face extends upward from the first bumper face, to define a second portion of the impaling edge, wherein the impaling edge, when viewed from above is a substantially V-shaped surface converging to the arcuate impaling portion. The second and third bumper faces work upon the fluke entering a kerf by engaging a wall of the kerf and forcing the fluke to move toward the plane of the bar. The arcuate impaling portion of the fluke permits the fluke to slide along the kerf wall without digging into it while the bar moves parallel to its length.

[0017] An optional feature of the present invention is the ability to draw the fluke back into the guide bar when desired to make infrequent cuts, such as cuts made along the top edge of the bar. This is easily done with a retractor next to the fluke. Preferably, the retractor includes a cam wheel; operation of the cam wheel brings its rise to bear on a free end of the spring to twist the spring and rotate the fluke into the bar. The retractor cam can also have the lateral limit stop. Obviously, when actuated, the retractor disables the safety feature of the invention, and kickback becomes possible.

[0018] The use of one anchor in a saw bar is sufficient to prevent rotational kickback. However, more than one anchor may be used, and, if there are, it is recommended that they be spaced apart. An anchor should be as close to the nose of the bar as possible since a fluke must be in the kerf to stop kickback and since kickback starts at the nose. A second fluke could be located in about the middle of the bar. When more than one anchor is used, the flukes may extend alternately from each side. When spaced apart, the vertical pressure on the base of the fluke when kickback starts will cause the bar at that point to be pressed or wedged flat up against the side wall of the kerf. There is very little space between the side of the bar and the kerf wall, and a thin saw bar is flexible enough to be forced against the kerf wall at the location of the fluke when the bar has two spaced apart flukes. This makes the fluke engagement firm and unyielding.

[0019] Another important feature of the invention is_' the biasing of the fluke to induce it to engage and dig into the side wall of the kerf to stop kickback. The feature provides a balance between two elements of the invention to provide an optimum. First, the torque of the spring provides a bias pressure to the point of the fluke. But, this spring pressure should be moderated or minimized. If the spring pressure is great enough by itself to dig into a kerf wall at kickback, it makes the fluke too stiff to easily enter the kerf, and this pressure against the wall slows the cutting of the saw, unless great feed pressure is applied to the bar. The greater the bias angle of the fluke, the less spring bias that is needed. But, to reduce the spring bias enough, it is necessary to have a large bias angle, which is difficult in a very thin saw bar for lack of lateral space. Therefore, to increase the bias angle of the fluke the base of the fluke pivot is moved off center and to the side of the bar opposite the fluke. This combination of angle bias and spring bias makes an ideal combination that has a minimum resistance to entering the kerf, and moving in the kerf during normal motion, and is very effective in stopping kickback.

[0020] These and other features, aspects, and advantages of the present invention will become more apparent from the following description, appended claims, and drawings.

Brief Description of the Figures

[0021] 

FIGURE 1 is an elevational view of the preferred form of the guide bar and anti-kick anchor of the present invention;

FIGURE 2 is an elevational, sectional view of the guide bar FIGURE 1 taken in the plane 2-2 of FIGURE 1:

FIGURE 3 is a sectional view taken in the plane 3-3 of FIGURE 1 showing the anchor and its retractor in cross-section;

FIGURE 4 is a sectional view of a fluke of the anchor and the retractor taken in the plane of 4-4 of FIGURE 1;

FIGURE 5 is an enlarged view of the fluke and torsion spring of the anchor in side elevation;

FIGURE 6 is a perspective view of the fluke, a base pivot, and a lateral stop showing the cooperation of these components;

FIGURE 7 is an elevational view of an alternate but not preferred embodiment of the present invention;

FIGURE 8 is an elevational, partial view of another embodiment of the present invention;

FIGURE 9 is an elevational, sectional view of the fluke and bar of the present invention in a kerf preventing kickback;

FIGURE 10 is a cross-sectional view of a log being cut by a chain saw incorporating the anti-kickback anchors of the present invention;

FIGURE 11 and 12 are cross-sectional views of a log being cut by a pivoting of the chain saw incorporating the anti-kickback anchors of the present invention;

FIGURE 13 is a cross-sectional view of a log,, adjacent another object, being cut by a chain saw incorporating the anti-kickback anchors of the present invention;

FIGURE 14 is a cross-sectional view of a log being cut by using a top edge of the chain saw blade;

FIGURE 15-19 show, the sequential steps involved in the cutting of a log using a chain saw of FIGS. 1-9;

FIGURE 20 is a plan of an upstanding tree or log being cut by a chain saw incorporating the anti-kickback anchors of the present invention;

FIGURES 21-25 show, the sequential steps involved in using a chain saw guide bar including the anti-kickback anchors of the present invention for cutting a log using a chain saw of FIGS. 1-9;

FIGURES 26-27 is a cross-sectional view of a log linearly pinching a prior art chain saw guide bar; and

FIGURE 28 is a cross-sectional view of a log linearly pinching a chain saw guide bar including the anti-kickback anchors of the present invention.

Description of the Preferred Embodiments

[0022] Before proceeding with the description, a convention mentioned earlier will be repeated: "vertical," "up" and "down" refer to direction and dimension with respect to the guide bar, and these correspond to the vertical in Figures 1 and 2. "Length" refers to the longest guide bar dimension and the direction along that, dimension, and these correspond to the horizontal in Figure 1. "Width" is the thickness direction, and this is along the horizontal in Figure 2.

[0023] Figure 1 shows in plan view a preferred form of the chain saw guide bar and anchor combination 10 of the present invention. A guide bar 12 of standard configuration mounts a first or front and a second or rear, relative each other, tandomly-aligned anchors 14 and 16. The relationship between anchor 14 and bar 12 accurately depicts the proper relative size of the two; however, anchor 16 has been enlarged relative to bar 12 so that the anchor can be seen more readily. The bar has a nose 18, a chain track 20, and a guide bar base 22. A conventional saw chain 23 tracks on track 20 counterclockwise in the Figure. Track 20 has a continuous slot ₂4 that receives drive links of the chain that keep the chain on the track. Guide bar base 22 attaches to the power and control end 25 of the chain saw in a conventional manner.

[0024] Anchors 14 and 16 mount in slots 26 and 28 formed in the bar. As can be seen readily in Figures 1, 2, and 3, anchors 14 and 16 have flukes 30 and 32, extending upward and outward relative the plane of the guide bar from a first guide bar side 15. These flukes protrude at an angle from a first side of the plane of the guide bar, to engage at their upper edges, the lateral walls of a kerf at the start of kickback. Since: - guide bars are generally on the order of about 0.15₀ to about 0.1875 (three-sixteenths) inches thick, in the preferred form the fluke is commensurately angled from about 40 degrees to about 50 degrees relative the plane of the bar to extend laterally outward about the width of the guide bar, e.g. about 0.150 to about three-sixteenths of an inch from the guide bar surface. In addition guide bar dimensions may vary, and as such, would include a, commensurately angled and laterally projecting fluke.

[0025] With reference specifically to anchor 16 and Figures 1 and 3, fluke 32 is at a free end of a torsion spring or spring plate 36. The torsion spring is mounted to the chain saw guide bar 12 at a rivet 38 in a base portion 40 of the anchor, substantially parallel to the plane of said guide bar, to provide for increasing rotation about a longitudinal guide bar axis while limiting rotation of the fluke about lateral guide bar axis substantially perpendicular to the longitudinal guide bar axis. A pocket 42 in the bar receives base portion 40. As seen best in Figure 3, a back wall 43 of the pocket lying parallel to the plane of the bar provides attachment for rivet 38 to the bar. Extending forward from the base portion 40, is a mid-portion 45 of the torsion spring 36. In the preferred form the mid-portion includes a pair of serpentine rectilinear undulations in the form of square undulations 44 and 46. These undulations and base 40 lie in the plane of the guide bar 12. The rectilinear undulations facilitate flexibility about a longitudinal guide bar axis, i.e., "roll" motion, while maintaining rigidity or limiting rotation about the transverse axis perpendicular to the longitudinal guide bar axis, i.e. "pitch" and "yaw" motion. Generally a torsion spring may not need rectilinear undulations if the mid-portion 45 is of sufficient additional commensurate length to provide similar concurrent flexibility and rigidity. For the purposes of illustration and not limitation such additional length may be about twice the horizontal dimension of the preferred serpentine form. As can be seen by comparing Figures 3 and 5, the torsion spring has a dimension in the plane of the bar substantially greater than the width dimension of the spring.

[0026] As best seen in Figures 4, 5, and 6, the mid-portion 45 terminates in a foot portion 48 of the anchor, having a first or bottom foot portion edge 49 and an opposite second or top foot portion edge 51. The foot portion extends laterally outward and downward from the mid-portion of the anchor to displace the bottom edge off-center relative the guide bar's central longitudinal axis towards a second side 17 of the guide bar for pivotal abutment with the chain saw guide bar about a longitudinal axis. In other words a first bend 53 in said anti-kickback anchor extends the foot portion of the anti-kickback anchor towards the second side 17 of the guide bar opposite the fluke, i.e. opposite the first side of the chain saw guide, through which the fluke projects. In the preferred form, the first bend 53 about a first longitudinal guide bar axis, formed between the mid-portion and foot portion of the anchor, angles or displaces the bottom edge 49 relative the plane of the guide bar, and thus the foot portion bears against a shoulder stop in the form of a pivot 50. The pivot is L-shaped and supports the fluke at its free end against forces perpendicular to the plane of the bar that tend to bend the fluke towards the bar about a vertical axis, i.e. yaw, and vertical forces acting downwardly that tend to bend the fluke in the plane of the bar about an axis perpendicular to the plane of the bar, i.e. pitch. The pivot makes the fluke stiff against these forces. In other words, the pivot acts as a stop to bias the fluke inward towards the plane of the guide bar and restrain the downward pivotal movement of the fluke. The pivot confines spring deflection to essentially twisting about a longitudinal axis, i.e. roll. The pivot also results in a short moment arm between it and where kerf wall forces act on the fluke to produce torsion in the spring. As seen in Figure 4, vertical wall 52 of the pivot engages foot 48, resisting horizontal forces acting on the fluke toward the plane of the bar. A horizontal wall 54 of the pivot engages foot 48 on the second guide bar side 17 substantially opposite the side from which the fluke extends or projects, i.e., from the first guide bar side 15, resisting vertical forces acting downward on the fluke.

[0027] As can be seen in Figures 4 and 6, in one preferred form, the top edge 51 of foot 48 bears on a lateral stop 58 in the form of a back wall 59 of a cam wheel retractor 60 when a kerf wall is not forcing the fluke toward the plane of the bar. The back wall of the camming wheel applies a preload to foot 48 that twists the fluke clockwise in Figure 4. When a kerf wall forces the fluke toward the bar plane and the foot off from the camming wheel, the torsion in the spring increases, and with the high angle bias of the fluke, induces the fluke to dig into the wall of the kerf when kickback begins, and not to merely retract toward the plane of the bar. A preload of about one-half to about two pounds force has proved satisfactory.

[0028] As seen in Figures 1, 4, and 5, fluke 32 bends away from the plane of the torsion spring to steeply incline the fluke relative to the guide bar plane and kerf sidewalls. In the preferred form, the fluke is angled relative the vertical or long transverse axis through two bends: the first bend 53 about a first longitudinal chain saw guide bar axis, the first bend adjacent the proximate leg of undulation 46; and a second:. bend 62, about a second longitudinal chain saw guide bar axis, at the junction between the base portion of the fluke and the torsion spring. Both the fi-st and the second bend steeply incline the fluke upward and outward relative the guide bar plane, while the first bend displaces the bottom edge 49 of the foot portion towards the shoulder pivot as earlier described. The same bends are in fluke 30. Relative to the vertical and as assembled with the camming wheel bearing on foot 48, the first bend . 53 is angled outward, in the preferred form, to a working angle from about 10 degrees to about 25 degrees relative the plane of the guide bar and mid-portion 45, depending upon the gauge or thickness of the chain saw guide bar used. In the preferred form, the first bend angle is bent in excess of its working angle from about 4 degrees to about 6 degrees. Upon mounting of the anchor to the guide bar, the top edge 51 of the foot portion is abutted with the back wall 59 of the cam wheel retractor 60 as earlier described. In a second preferred form, as shown in Fig. 8, the lateral or limit stop 58 on the side of the guide bar from which the fluke extends, i.e. the first guide bar side 15, will compress the fluke about a longitudinal axis about 4 degrees to about 6 degrees. As a result, when the anchor equipped guide bar is outside the kerf, the top edge 51 rests with slight pressure against the limit stop when the anchor equipped guide bar is inserted into the kerf, the kerf sidewall pushes the fluke inward relative the guide bar plane, off the limit stop and torque biases the fluke outward relative the plane of the guide bar. In the preferred form, the pressure transmitted to the fluke limit stop may vary from about one-half to about 2 pounds, depending upon the excess bend applied.

[0029] In addition, in the preferred form, as shown in Figure 5, the second bend 62 is angled outward from about 25 degrees to about 35 degrees relative the plane of the foot portion 48 to additionally increase the angle of or steeply incline the fluke relative the plane of the guide bar and thus, the kerf sidewall. In other words, the second bend in the anti-kickback anchor, about a second longitudinal chain saw guide bar axis, extends the fluke outward from the plane of the foot portion to project beyond the plane of the first side 15 of the guide bar, a distance substantially equal to about the thickness of the chain saw guide bar. In addition, the height of the foot portion 48, i.e. the distance of top edge 51 relative the bottom edge 49, is, in the preferred form, greater than the analogous dimension in the mid-portion 45, to provide sufficient extension or projection of the fluke while maintaining flexibility. For the purposes of illustration and not limitation, the foot portion 48's height may be about one-quarter of an inch while the analogous mid-portion dimension is about three-sixteenths of an inch. In the preferred form, the final fluke angle relative the plane of the guide bar includes angles from about 4₀ degrees to about 50 degrees. The preferred angle ranges are to accommodate the variety of guide bar thicknesses earlier described, as thicker (short transverse dimension) chains and guide bars cut wider kerfs, requiring an increased fluke angle relative the guide bar plane. While the preferred angle ranges for the first and second bends have been described, the end result is that the fluke extends outward a distance substantially equal to about the thickness of the chain saw guide bar used.

[0030] As seen in Figures 3 and 5, a fluke 32, including bumper deflector means, is provided which is extendible upward and outward from said chain saw guide bar to allow only longitudinal and downward guide bar motion relative the kerf. More specifically, as shown in Figure 1 and 5, the fluke 32 includes sloping faces in the downward, forward and rearward directions relative to the chain saw guide bar. A first or downward facing bumper face 160, integral with the feet portion 48, extends upwards and outwards to an apex 64 at its outermost extremity. In the preferred form the first bumper face 160 is a triangularly shaped portion connected along a first bumper face base portion 162 at the second bend 62. By this construction, if the fluke moves out of the kerf, the downward sloping face acts as a bumper to deflect the fluke into the plane of the chain saw guide bar upon downward motion of the guide bar within the kerf and upon downward entry into the kerf.

[0031] As shown in Figures 3 and 5, in the preferred form, a second or leading bumper face 165, is folded back along a first top portion 167 of the first bumper face to extend upwards relative the first bumper face. In addition, the second bumper face has a second bumper face top portion 169 to define a first portion of a substantially horizontal impaling edge 173. A third or trailing bumper face 175, folded back along a second top portion 177 of the first or downward facing bumper face 160 to extend upwards relative said first bumper face, has a third bumper face top portion 179 to define a second portion of a substantially horizontal impaling edge 173. In the preferred form the two top edge portions 167 and 177 of the downward facing bumper face join together at the apex 64. The leading and trailing bumper face top edge portions together form or define the apex 64 within the V-shaped impaling surface or edge 173 when viewed from above the guide bar, i.e. along the "yaw" axis. By this construction, when the fluke moves out of the kerf, the acute angles of the leading and trailing bumper faces relative the chain saw guide bar act as bumpers to deflect the fluke towards the chain saw guide bar, enabling passage into the kerf, when entering the kerf longitudinally at the trailing or leading ends of the kerf, respectively.

[0032] In the preferred form, the arcuate portion ₁₈₃ includes the apex 64 joining the leading and trailing bumper face top portions. The arcuate portion, being the most laterally extendible point or outermost extremity of the fluke, engages the kerf sidewall and yet can easily move longitudinally within the kerf, providing additional deflector means for the fluke, there being no orthogonal surfaces to inhibit movement. While the inventor has specifically described the structure of the fluke, generally, other geometric permutations involving oblique surfaces in the forward, rearward and downward directions may be used. For example, an axially split frustrum or conical structure, having a wider diametered portion disposed vertically above a narrower diametered portion would suffice.

[0033] As previously mentioned, the anchor in transverse cross-section has a height dimension (long-transverse axis) substantially greater than its width (short transverse axis). Without considering shoulder pivot 50, this permits large fluke deflections at right angles to the plane of the bar as the fluke presses against the kerf wall and small downward fluke deflections in response to the resistance of the kerf wall acting vertically in the plane of the bar against upward fluke movement. Because of the thin cross-section, the anchor readily twists in torsion, and will do so because of pivot 50. Thus, in kickback the fluke exerts an upward force on the kerf wall and is resisted by the wall by downward forces parallel to the plane of the bar. The spring does not deflect much from these vertical forces because it is much stiffer in the vertical than in the horizontal, where displacement forces associated with a kerf wall during normal motion of the bar readily deflect the fluke. Foot 48 bearing on shoulder pivot 50 increases the lateral resistance of the spring to bending :. about a vertical axis in response to the fluke pressing against the kerf wall and forces the spring into torsion instead of bending. The foot and shoulder pivot also increase vertical bending resistance of the fluke against kickback forces. The foot and shoulder pivot in cocpera- tion with a kerf wall also increase the resistance of the torsional displacement at the outset of kickback. The undulations permit bending of the torsion spring by producing comparatively long moment arms in the legs of the undulations. This bending supplements the torsional' twist in permitting desired deflection o the fluke in response to kerf wall reaction forces during normal cuts.

[0034] Anchor bearing bosses 67 and 68, seen in Figure 1 for forward anchor 14, formed in the bar in the perimeter of slot 26, engage the horizontal portions of the torsion spring at the fluke to further enhance the effective vertical stiffness of the spring. (Boss 68 does this when the anchor is turned over to reverse the bottom and top of the saw bar.) As shown in Figure 6, for anchors formed of thin material it may be necessary to back the spring pivot that complements pivot 50, and this can be done with boss 67. Boss 67 has a vertical wall 69 that engages the spring and fluke base to resist lateral displacement in the manner of vertical wall 52 of pivot 50. A horizontal wall 70 of boss 69 engages the fluke and spring to resist their downward bending.

[0035] The slot in which the anchor mounts is deeper outside the bosses to provide clearance for the anchor spring perimeter when the undulations move when twisted. This also provides ample clearance to prevent clogging with debris. The clearance and the integration of the spring and fluke are major improvements over the prior art, which was prone to gumming up and inactivating moving parts. Furthermore, the reversibility or the ability of the flukes to be turned over within the slots 26 as previously described enables the operator to make use of the unworn side of the saw bar by reriveting.

[0036] As can be seen Figures 4 and 9, as the fluke tends to rise in response to the outset of kickback, its impaling edge 173 digs into a wall 71 of a kerf, and the kerf wall prevents further vertical movement of the bar by imposing a vertical downward force on the bar through the fluke. The vertical force of the kerf wall tends to rotate the fluke counterclockwise in the Figures. This tendency towards rotation is resisted by a horizontal force (the horizontal arrow in Figure 4) exerted by the kerf wall on the fluke that increases the deeper the fluke cuts into the wall. The base of the fluke cannot move downwardly or horizontally because it is in engagement with shoulder pivot 50. The horizontal force of the kerf on the fluke is resisted at the shoulder. The clockwise moment about the pivot caused by the horizontal kerf wall reaction equals the counterclockwise moment of the spring torsion and that results from the vertical force of the kerf on the fluke. During normal operation, the kerf wall only imposes a horizontal force on the fluke and the fluke readily responds to this force and moves towards the plane of the bar.

[0037] An important optional feature of the present invention is in retractor cam 60 for selectively retracting the fluke into the chain saw guide bar to disable the anti-kickback anchor, e.g. the fluke into the bar when making unusual cuts, such as a cut with the top edge of the guide bar. The retractor is seen in top and bottom views in Figure 1 (identical retractors serve both anchors), in half section in Figure 3, and in elevation in Figure 4. Retractor cam 60 mounts to a stabilizer base 72 for rotation on the base. The cam wheel has a screwdriver slot 76 to actuate it. The cam wheel mounts for rotation on the base through staked axle 78. As seen best in Figure 3, the wheel has a step or notch 80 that receives foot 48 of the fluke. This notch is bound on one side by back wall 59 that engages the top edge ₅1 of front foot portion 48 of the anchor. The cam has a cam surface 82 that can bear on foot 48 and rotate the fluke inwardly upon rotation of the wheel. Surface 82 engages the foot and exerts a bending moment on it, forcing the fluke into the bar. Stabilizer base 72 also includes shoulder pivot 50 that couples the fluke to the bar to increase its resistance to downward forces.

[0038] When the anti-kick saw bar is out of a cut, the fluke is fully expanded, and rests against its lateral stop 58. Its lateral expansion is much greater than the kerf width. Upon entering the kerf, the wall forces the fluke toward the plane of the bar. And at all times while in the kerf, the spring bias keeps the impaling edge of the fluke firmly pressed against the kerf wall. The spring bias pressure, say about one-half to about two pounds, is constant because spring torsional deflection is constant. The spring bias pressure alone is not always sufficient to cause the impaling edge of. the fluke to bite into the kerf wall at kickback. If the bias spring pressure is too strong, it is difficult to enter or move within the kerf with the bar, due to resistance caused by the spring pressure. The one-half to two pounds force on the fluke is sufficient to keep the fluke in position and ready to penetrate the wall. When kickback starts, the bar starts to rise, the high angle bias will wedge the impaling edge of the fluke into the kerf wall, and kickback stops instantly. During kickback, the angle bias of the fluke dominates. The angle bias is used only if the bar starts to rise; in all other movements of the bar, forward or back, or down, it does not come into play. Due to the limited space in a thin saw bar laterally, the base of the fluke is off center and is supported at the far side of the bar from the fluke to steeply incline or increase the angle of attack of the fluke relative the kerf wall as much as possible. The combination of the spring pressure and angle bias is very effective in stopping kickback. In conclusion the torsion spring plate of the present invention biases the fluke laterally into contact with the side wall of the kerf with a minimum of lateral pressure, and, because of the shape and construction of the fluke, can move easily relative to the kerf only, longitudinally and downwardly and yet readily engage the sidewall of the kerf as the chain saw guide bar moves upward, thereby aborting kickback.

[0039] As shown in Figure 3, base 72 has an ear 83 that extends into pocket 42. The ear attaches to the bar laterally of the pocket through a rivet 84. As can be seen by comparing Figure 1 and 3, base 72 has a recess 86 with a circular perimeter 87 that receives cam wheel 60. A transverse wall 89 of the base abuts the end of the bar that bounds the back of the pocket. As can be seen in Figure 3, foot 48 is at an angle relative to the cam wheel and the cam surface of the cam wheel can ride against the foot and force the fluke to rotate into the bar.

[0040] Figure 3 shows pocket 42 of the bar that receives a base 40 of the anchor and retractor cam 60 so as to present surfaces flush with the contiguous surface of the bar. These pockets are identical but lie on opposite sides of the bar and face each other.

[0041] As mentioned earlier, the present invention can use anchors aligned in tandem in a bar with flukes extending from either side of the bar or from the same side of the bar. It is important to have the leading anchor as close to nose 18 as possible because it is at the nose that kickback begins. The advantage of having a:.. single fluke, or of having the multiple flukes on the same side of the bar, or of having flukes extending in opposite directions from the bar can be seen in Figure ₉. When kickback begins with the preferred fluke arrangement, bar 12 moves flat against a kerf wall ₇₁a opposite the wall 71 engaged by impaling edge 173 of the fluke. The bar, in effect, wedges against wall 71a. This makes the fluke engagement firm and unyielding. It also presents the maximum bias angle of the fluke to the engaged kerf wall.

[0042] The operation of the anchor and bar at the outset of kickback will now be described with reference particularly to Figures 1, 4, 6 and 9-26.

[0043] During the making of a cut, the chain rotates counterclockwise in Figure 1. Suppose that nose 18 is within a log, not free of the log. The teeth going around the radius of the nose cut a vertical wall in the log. In the event of a sudden increase in resistance presented by the log, as when an operator changes the position of the bar, the bar will tend to react'by moving rapidly in a clockwise arc. But the bar cannot rotate because fluke 30 digs into side wall 71 of the kerf. The side wall of the kerf resists the considerable upward force imposed on it by the fluke, and the fluke will tend to bend counterclockwise in Figures 4 and 9 but cannot because shoulder pivot 50 engages the base of the fluke, the kerf wall imposes a counteracting moment, and due to the bias angle of the fluke, as the bar is forced up by kickback, the base of the fluke, as with a vaulting pole, swings the bar out, and it wedges tightly against wall 71a, enhancing the effective rigidity of the fluke. (When the fluke is in a kerf, the back wall of the camming wheel no longer supports top edge 51 of foot 48.) Accordingly, the guide bar and chain cannot move vertically, and kickback stops instantly. If kickback ;.: begins with anchor 16 also in the kerf, both flukes 30 and 32 will engage the lateral wall of the kerf to stop the kickback.

[0044] Figure 7 shows an alternate embodiment 88 of the present invention especially suitable for short saw guide bars. There, a pair of anchors 90 and 92 mounted in the bar stacked on top of each other. Each of the anchors has a fluke extending laterally outward of the plane of the bar, with the flukes extending from opposite sides of the bar. The construction of the flukes, the consideration of the torsion spring, and retractor cams are identical with those previously described, and so this description will not be extended. Although this alternate embodiment will stop kickback, it is not preferred.

[0045] Figure 8 illustrates another preferred embodiment of the present invention characterized in the use of a different approach to stabilizing the end of the torsion spring than in the previously described embodiments. In Figure 8, a saw bar 100 mounts an anchor 102 that includes a torsion spring 104, and a stabilizer base 106. Stabilizer base 106 performs all the functions of the base and cam wheel of the previously described embodiments except the retraction function of the cam wheel. As such, it provides a torsional preload on spring 104, a pivot for a foot of the torsion spring, and structure to resist the forces and moments of kickback. This is done as follows:

[0046] Base 106 has a wall 108 flush with the adjoining surface of the saw bar. The wall includes a boss 110 that serves the function of the back wall of the cam wheel by providing bearing support for a foot 111 of spring 104, the foot corresponding to foot 48 of spring 36 in the earlier described embodiment. The bar also has an interior wall 112 that together with wall 108 defines a pocket for foot 111. A horizontal wall 113 and an interior vertical wall 114 defines a shculder pivot in the manner of shoulder pivot 50 of the previously described embodiment. As such, foot 111 engages walls 113 and 114 and is capable of pivoting about an axis proximate the juncture of these two walls.

[0047] Boss 110 bears on an edge 116 of spring 104 to maintain a torsional stress in the spring and a resistance moment arm in the manner of the embodiment previously describe.

[0048] Base 106 has an ear 118 received in a pocket in the bar and in contact with an interior wall 120 of the bar to present overlapping walls secured together by a rivet 122. As in the previously described embodiment, torsion spring 104 has a fluke 124 that extends laterally from the plane of the bar towards the viewer in Figure 8. As before, the spring has undulations to induce greater deflection in bending than would otherwise occur. As before, the slot in the bar has bosses 126 to arrest vertical deflection of the spring in the plane of the bar, and the slot is made symmetrical for reversing the top and bottom of the bar.

[0049] Thus, there is more than one embodiment of the invention. The Figure 8 embodiment does not have the ability to draw the fluke back into the guide bar, thus making the bar safe from kickback at all times.

[0050] More than one anchor fluke may be mounted into a saw bar. Either both on one side or alternate. If alternate, it is recommended that they be spaced apart, lengthwise of the saw bar axis.

[0051] The most important aspect of the present invention is to arrest kickback. But the present invention also has utility for other purposes. The nose anchors provide a fulcrum holding the saw bar stationary at the fulcrum and permitting an operator to rotate the saw bar about it. With a saw bar without the anchor, this is an invitation to kickback.

[0052] The saw bar and anchor of the present invention permit the use of a large radius at the nose of the saw bar; the anchor permits elimination of the small radius in some bars to prevent kickback. This gives back maximum efficiency to the cutting chain and efficient uses while boring into or through a log.

[0053] As shown in Figure 10, in bucking or cutting generally transverse or perpendicular to the longitudinal axis of a log 130 wider than the longitudinal length of the chain saw guide bar 12, there is no danger of rotational kickback since flukes 3₀ and 32 will engage the kerf wall as previously described and prevent it. As long as one or both of the flukes are within the kerf, the engagement of the impaling edge with the kerf will preclude rotational kickback.

[0054] In bucking or cutting generally perpendicular to the longitudinal axis of a log, the log being narrower in the transverse axis than the longitudinal length of the chain saw guide bar, the presence of the pair of anchors 14 and 16 can facilitate cutting as well as prevent rotational kickback. As shown in Figure 11, the operator will set the motor hooks 131, generally adjacent the power and control end 25 or rear anchor 16 into the log 130, and, using the motor hood or anchor as a pivot, raise the power and control end 25 of the chain saw as indicated by the arrow 132, to displace the nose of the chain saw guide bar downward relative the log as indicated by the arrow 134, since the fluke ₃0 of the first anchor 14 will prevent the nose of the guide bar from rising within the cut. As a result, a single man on one side of the log can perform the work as safely as two men on opposite sides fo the log. As shown in Figure 1₂, with the nose 18 of the bar secured within the kerf by the first anchor 14, the operator may pivot the motor end 25 of the chain saw downward relative the nose end, as indicated by the arrow 138, to provide a very fast, easy and safe cutting manuever. So long as at least one anchor is within the transverse dimension of the log, the operator will always be safe from rotational kickback.

[0055] Another advantage of the chain saw guide bar incorporating the anchors of the present invention is shown in Figure 13. Often times, even though the operator is using a chain saw guide bar 12 having a length longer than the transverse dimension of the log being cut, engagement of the nose 18 of the chain saw guide bar with another object 140, e.g., another tree, the anchor 16 will preclude rotational kickback, even if the first anchor 14 is outside the kerf. However, at least one anchor must always be within the kerf to preclude rotational kickback.

[0056] In some situations, as shown in Figure 14, the log may be "lying tight" or resting close to the ground, preventing the chain saw from extending all the way down to complete the cut. In one preferred form, the chain saw equipped with the anti-kickback anchor of the present invention can be retracted if the operator decides that he or she must make an undercut (a cut directed upward relative the log). While in the operational mode, the anti-kickback anchors will preclude such motion, by rotating the cam wheel as described earlier, the fluke 14 or 16 will be retracted into the plane of the guide bar, enabling use of the top edge of the guide bar. However, it is imperative that the flukes be returned to their operational position extended outside the plane of the guide bar. Indeed this maneuver should only be practiced by professionals and cannot be practiced by one of the preferred forms having non-retractable anchors as described earlier and shown in Figure 8.

[0057] Another attribute of the anchor is the elimination of roughness, chatter and jumping of the saw bar that occurs when making a bore cut without the anchor. Without the anchor, the bar tries to climb up the end of the bore, throwing the top of the circulating chain with great force onto the top of the bore cut, causing the chain to grab and force the saw back towards the operator; the operator then shoves the saw forward again to the end of the cut, and the same thing happens again. The anchor holds the saw bar and does not permit it to rise in the bore so that the teeth of the chain do not grab the top bore wall.

[0058] Still another advantage of the invention is evidence when sawing through a fallen tree when the tree has fallen over a swale or low place, which causes the tree to have no support at its center. A bucking cut on such a log causes the log to pinch in on the top of a cut onto the chain, preventing any further cutting. As shown in Fig. 15, with a chain saw guide bar including the anti-kickback anchors of the present invention, a first saw cut is made into the top of the log, stopping before the log pinches the saw bar but with the first or nose anchor 14 well within the kerf. Then, as shown in Figure 16, the operator pulls the saw bar towards himself leaving the nose anchor fluke safely within the kerf. The operator then cuts down a few inches leaving enough uncut wood 144 above the saw bar to keep the log from pinching. As shown in Figure 17, the operator then makes a bore cut completely through the log, leaving the wood previously left uncut to keep the log from pinching. As shown in Figure 18, the operator then cuts down completely through the log as indicated by arrows 146. As shown in Figure 19, the operator then completes the cut by sawing through the uncut wood 144 left during the earlier part of the procedure.

[0059] Another significant advantage of the present invention is its ability to provide a safe and economical way to fall a tree when a tree has a diameter larger than the length of the saw bar. With a conventional saw the operator must make one-half of the falling cut from each side of the tree. In making the second cut, the saw must be turned over, making the throttle position awkward; it also causes exhaust from the motor to come up into the operator's face. To avoid this, some operators use the back side or top edge of the saw bar, which is dangerous and awkward. Use of the top edge increases the danger of lateral pinch kickback. As shown in Figure 20 so long as the operator keeps at least one anchor within the kerf, such awkward manipulations are unnecessary, since rotational kickback is precluded. Indeed the use of the anchors as fulcrums or pivots further eases the cutting trees as the saw bar can be walked about the tree's londitudinal axis, especially if the bar is long, spacing the flukes well apart.

[0060] For example, as shown in Figures 21-25, the chain saw guide bar incorporating the anti-kickback anchors of the present invention can easily and safely fell a large upstanding tree. As shown in Figure 21, with the anchor in the saw guide bar 12, the operator makes a second cut 148 behind the undercut 149, leaving some wood portion indicated by the arrow 150 between the second cut and the undercut, keeping the nose free of the tree 130 until the second anchor 16 in the middle of the bar is within a kerf. As shown in Figure 22, using this anchor as a pivot, the guide bar is swung around as indicated by the arrows 151 and 152 in an arc to bring ;-< the nose well into the wood. The guide bar is now removed and positioned as indicated in Figure 23. As shown in Figure 24, the chain saw now makes a boring cut to the center of the tree by applying axial longitudinal pressure upon the power and control end 25 of the chain saw. Finally, as shown in Figure 25, the first fluke 14 of the bar holds the nose end of the bar stationary while the operator swings the power and control end 25 of the bar around the nose anchor as a fulcrum about 180, degrees, cutting a semi-circular kerf in the tree opposite the undercut in considerably less time, falling the tree.

[0061] A further additional advantage of the chain saw guide bar including the anti-kickback anchor of the present invention is the reduction of linear pinch kickback. A shown in Figure 26, as the cut moves downward relative the top portion 154 of the log 130, the parallel sidewalls of the kerf move inward relative each other, pinching upon the chain 23. Continued pressure upon the chain eventually cannot be compensated by the continued rotation of and cutting action by the chain, pinching upon the chain at point 156 and pulling the chain upwards out of the bar groove. The chain lags further behind the downward cutting guide bar and chain until pinch pressure halts the rotational motion of the chain. The distance the cut can be advanced downward depends upon the amount of slack in the chain. When the motion of the chain is halted, the linear pinch kickback begins.

[0062] A shown in Figure 27, as the bar kicks back, the guide bar 12 raises upward relative the log 130 being cut to a position adjacent the point of pinch 156, as indicated by the arrows 158. Concurrently, the rotational inertia of the chain about the guide bar, in conjunction with the halting of its rotation by the pinching as just described, imparts a kick generally axially rearward cowards the operator. As shown in Figure 28, a chain saw guide bar including an anti-kickback anchor of the present invention, resists the upward motion of the guide bar relative the log as just described. Thus the linear kickback is reduced by the increased pull gradient indicated by the arrow 159 and/or the maintaining of the rotating chain in contact with the cutting surface of the log.

[0063] The anchor bar of the present invention eliminates the need of considering kickback in making a chain; extra parts are not needed and the chain can be designed with maximum cutting efficiency. Obviously chain brakes are no longer necessary, with their weight and cost.

[0064] It will be apparent from the foregoing that while particular forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.

Claims

1. In combination with a chain saw guide bar, an anti-kickback anchor comprising:

a fluke, extendable upward and outward from said chain saw guide bar, said fluke including bumper deflector means for allowing only longitudinal and downward guide bar motion, and an arcuate impaling edge for precluding any substantial upward motion of said chain saw guide bar; and

means for mounting said fluke to said chain saw guide bar.

2. An anti-kickback anchor as set forth in claim 1, wherein said impaling edge has an apex extending laterally outward and upward from said chain saw guide bar, said impaling edge having an arcuate portion including said apex and providing additional deflector means for said fluke.

3. An anti-kickback anchor as set forth in claim 1, wherein said bumper deflector means further includes sloping faces in the downward, forward and rearward directions relative to said chain saw guide bar, said faces together defining an apex within said impaling edge extending laterally from said chain saw guide bar.

4. An anti-kickback anchor as set forth in claim 1, wherein said bumper deflector means includes:

a first bumper face facing downward relative to said chain saw guide bar, said first bumper face extending upwards and outwards to an apex from said means_' for mounting said fluke,

a second bumper face folded towards the plane of said chain saw guide bar from said first bumper face, said second bumper face extending upward from said first bumper face, to define a first portion of said arcuate impaling edge,

a third bumper face folded toward the plane of the guide bar from said first bumper face, said third bumper face extending upwards from said first bumper face to define a second portion of said arcuate impaling edge, wherein said impaling edge includes a substantially V-shaped surface defined by said second and third bumper portions at said impaling edge.

5. An anti-kickback anchor as set forth in claim 1, and further including means for selectively retracting said fluke into said chain saw guide bar to disable said anti-kickback anchor.

6. In combination with a chain saw guide bar, an anti-kickback anchor, comprising:

a fluke, extending upward and outward relative the plane of said guide bar to project from a first side of said chain saw guide bar, said fluke including an arcuate impaling edge at its outermost extremity; and

means for mounting said fluke to said chain saw guide bar, said means for mounting said fluke to said chain saw guide bar including means for steeply inclining said fluke relative to said plane of the said guide bar plane.

7. An anti-kickback anchor as set forth in claim 6, wherein said means for steeply inclining said - fluke relative to said plane of said guide bar includes a foot portion of said means for mounting said fluke, said foot portion having a first foot portion edge, said first foot portion edge pivotally abutting said chain saw guide bar adjacent a second side of said chain saw guide bar opposite said first side of said bar through which said fluke projects.

8. An anti-kickback anchor as set forth in claim 7, wherein said chain saw guide bar includes a lateral stop and wherein said fluke includes a second foot portion edge, said second foot portion edge abutting said lateral stop to bias said fluke inward towards said plane of said guide bar and restrain the downward pivotal movement of said fluke.

9. An anti-kickback anchor as set forth in claim 7 wherein said means for steeply inclining said fluke relative said plane of said guide bar further includes at least one bend outward from said plane of said guide bar, within said means for mounting said fluke to said chain saw guide bar.

10. An anti-kickback anchor as set forth in claim 9, wherein said at least, one bend outward from said chain saw guide bar plane angles said fluke a distance substantially equal to about the thickness of said chain saw guide bar.

11. An anti-kickback anchor as set forth in claim 9 wherein said means for steeply inclining said fluke includes:

a first bend in said anti-kickback anchor about a first longitudinal chain saw guide bar axis to extend said foot portion of said means for mounting said fluke to said chain saw guide bar towards said side of said guide bar opposite said impaling edge, and

a second bend in said anti-kickback anchor about a second longitudinal chain saw guide bar axis to extend said fluke outward from the plane of said foot portion to project beyond plane of said first side of said guide bar, a distance substantially equal to about the thickness of said chain saw guide bar.

12. An anti-kickback anchor as set forth in claim 11, wherein said first bend is angled outward at about 10 to 25 degrees relative to said plane of said guide bar.

13. An anti-kickback anchor as set forth in claim 11, wherein said second bend is angled at about 24 to 35 degrees relative to the plane of said foot portion.

14. An anti-kickback anchor as set forth in claim 7, and further including means for selectively retracting said fluke into said chain saw guide bar to disable said anti-kickback anchor, said means for selectively retracting said fluke being mounted on said guide bar and abutting said anti-kickback anchor.

15. An anti-kickback anchor as set forth in claim 14, wherein said means for mounting said fluke to said guide bar includes means for increasing rotation of said fluke about a longitudinal guide bar axis and limiting said rotation of said fluke about lateral guide bar axes substantially perpendicular to said longitudinal guide bar axis.

16. An anti-kickback anchor as set forth in claim 15, wherein said means for increasing rotation of said fluke about a longitudinal guide bar axis and limiting rotation of said fluke about lateral guide bar axes substantially perpendicular to said longitudinal, guide bar axis includes serpentine undulations in said means for mounting said fluke to said guide bar.

17. An anti-kickback anchor as set forth in claim 16, wherein said means for increasing rotation of said fluke about a longitudinal guide bar axis and limiting rotation of said fluke about lateral guide bar axes substantially perpendicular to said longitudinal guide bar axis includes said mounting means having an elevational cross-section dimension substantially greater than its transverse dimension.

18. In combination with a chain saw guide bar, an anti-kickback anchor for engaging a sidewall of a kerf, comprising:

a fluke, extending upward and outward from said chain saw guide bar, said fluke including bumper deflector means for allowing only longitudinal and downward chain saw guide bar motion, said bumper deflector means defining an impaling edge for precluding any substantial upward motion of said chain saw guide bar; and

mounting means for mounting said fluke to said chain saw guide bar, said mounting means including means for steeply inclining said fluke relative to the guide bar plane.

19. An anti-kickback anchor as set forth in claim 18, wherein said impaling edge has an apex extending laterally outward and upward from said chain saw guide bar, said impaling edge having an arcuate portion including said apex and providing additional deflector means for said fluke.

20. An anti-kickback anchor as set forth in_' claim 19, wherein said bumper deflector means further includes sloping faces in the downward, forward and rearward directions relative to said chain saw guide bar, said faces together defining said apex within said impaling edge extending laterally from said chain saw guide bar.

21. An anti-kickback anchor as set forth in claim 20, wherein said means for steeply inclining said fluke relative to said plane of said guide bar includes a foot portion of said means for mounting said fluke, said foot portion having a first foot portion edge, said first foot portion edge pivotally abutting said chain saw guide bar adjacent the side of said chain saw guide bar, opposite said first side of said bar through which said fluke projects.

₂2. An anti-kickback anchor as set forth in claim 21, wherein said chain saw guide bar includes a lateral stop mounting said fluke has a second foot portion edge, said second foot portion edge abutting said lateral stop to bias said fluke inward towards said plane of said guide bar and restrain the downward pivotal movement of said fluke.

23. An anti-kickback anchor as set forth in claim 22, wherein said means for steeply inclining said fluke relative said plane of said guide bar further includes at least one bend outward from said plane of said guide bar, within said means for mounting said fluke to said chain saw guide bar.

24. An anti-kickback anchor as set forth in claim 18, and further including means for selectively retracting said fluke into said chain saw guide bar to disable said anti-kickback anchor.

25. In combination with a planar chain saw guide bar having first and second opposite sides, an anti-kickback anchor for engaging a sidewall of a kerf comprising:

a spring plate having a base portion substantially parallel to the plane of said guide bar, said base portion mounted to said chain saw guide bar, a mid-portion extending away from said base portion in said plane of said guide bar, said mid-portion having serpentine undulations lying in said plane of said guide bar, and terminating in a foot portion, having a first and a second edge, said foot portion extending laterally outward and downward from said mid-portion to displace said first edge off-center towards said second opposite side of said chain saw guide bar for pivotal abutment with said chain saw guide bar about a longitudinal axis; and

a fluke, extending upward and angled outward from said second edge of said foot portion towards said first opposite side of said chain saw guide bar, said fluke including a downward facing deflector bumper face, a leading bumper face, and a trailing bumper face, said bumper faces having sloping surfaces facing in the forward, rearward and downward directions relative said chain saw guide bar, said faces together defining a substantially V-shaped impaling edge disposed in the upward direction relative said chain saw guide bar, said V-shaped edge having an arcuate portion having an apex, said spring plate biasing said fluke laterally into contact with said sidewall of said kerf with a minimum of lateral pressure, whereby said fluke may easily move relative to said kerf only longitudinally and downwardly and yet readily engaging said sidewall of said kerf as said chain saw guide bar moves upward, thereby aborting kickback.

26. An anti-kickback anchor as set forth in claim 25, and further including means for selectively retracting said fluke into said chain saw guide bar to disable said anti-kick anchor, said means for selectively retracting said fluke including a cam rotably mounted to said chain saw guide bar and abutting a side of said anti-kick anchor, to selectively act upon said spring plate to draw said fluke within the confines of said chain saw guide bar.

Drawing