Abstract: An element for serial configuration with an adjacent element in an abrasive tool, wherein the element is arranged to be mounted on a flexible drive carrier having a drive direction D. The element comprising at least one protruding member extending in a direction parallel to the drive direction D. The at least one protruding member being configured to overlap with the adjacent element at least when the flexible drive carrier has a straight configuration, and to reduce a width of a gap G formed between the element and the adjacent element when the flexible drive carrier is configured bent in an arcuate form.

Abstract: Embodiments of chain saw cutter links, and related apparatuses and methods. For example, in some embodiments, a cutter link may include a top plate, a sharpened surface having an upper end and a lower end, and a depth gauge having a top surface. The sharpened surface may define a reference line tangent to the sharpened surface at the upper end such that the reference line extends between the top plate and the sharpened surface, a sharpened width may be defined by a minimum distance between the reference line and the lower end of the sharpened surface, an opening width may be defined by a minimum distance between the reference line and the top surface of the depth gauge, and the sharpened width may be greater than the opening width.

Abstract: A cutting chain (100) moving in a cutting direction (120) is disclosed in the present invention. The cutting chain (100) includes a cutting link (106), which further includes a cutting portion (120), a depth gauge (118) and a space (122) between the cutting portion (120) and the depth gauge (118). The cutting chain (100) further includes a bumper drive link (104) which is pivotally connected to the cutting link (106) and immediately precedes the cutting link (106) in the cutting direction (124). The bumper drive link (104) further includes a tail (204) and a body (202). The tail (204) of the bumper drive link (104) further includes a bent portion (206) and a straight portion (208). Further, the bent portion (206) is oriented in a substantially perpendicular direction relative to a plane (P) of the body (202) of the bumper drive link (104). Moreover, the bent portion (206) of the tail (204) extends into the space (122) between the cutting portion (120) and the depth gauge (118) of the cutting link (106).

Abstract: Embodiments herein provide a cutter link having an end of life indicator to provide feedback to the user that the saw chain, and more specifically the cutter link(s), has been worn and/or sharpened to an undesirable state or degree. There is provided one or more disruptions to the cutting surface of a cutter link in a region that is past the manufacturer's recommended wear limit. When exposed, such disruptions in the cutting surface provide perceptible indications to the user that the chain should no longer be used.

Abstract: Embodiments herein provide a modified pitch sprocket to provide an orientation of a saw chain link, such as a cutter link or drive link, with respect to the direction of travel of the link, as it traverses the sprocket that is different than the orientation of the link as it traverses a straight portion of the guide bar. In some embodiments, the modified pitch sprocket may orient the cutter link to provide radial extension for a depth gauge of the cutter link relative to a cutting element of the cutter link. This may facilitate shaping of the depth gauge and/or cutting element, such as by a sharpening element, as the cutter link traverses the sprocket.

Abstract: Embodiments provide various components of a chain saw, including saw chain elements, sprockets, and other fixtures, that may facilitate sharpening of cutter links during operation. In various embodiments, the components may increase stability during sharpening, provide nose mounted sharpening fixtures, and/or facilitate the resizing and/or reshaping of a sharpening element.

Abstract: Embodiments provide various components of a chain saw, including saw chain elements, sprockets, and other fixtures, that may facilitate sharpening of cutter links during operation. In various embodiments, the components may increase stability during sharpening, provide nose mounted sharpening fixtures, and/or facilitate the resizing and/or reshaping of a sharpening element.

Abstract: A cutting link (1) for a saw chain includes a base body (2) and a cutting tooth (3) mounted thereon and made of hard metal. The base body (2) has rivet openings (4) and a recess (6) is formed in the base body (2) for chip removal with the recess (6) being ahead of the cutting tooth (3) in running direction. A connecting leg (8) of the cutting tooth (3) is brought into surface contact laterally of the base body (2) and the cutting tooth (3) is firmly bonded to the base body (2) by brazing. The connecting leg (8) extends so far downwardly that a lower edge (13) thereof lies lower than the recess (6). The connecting leg (8) has an upwardly raised edge (15) in its rearward region opposite the neighboring rivet opening (4).

Abstract: Safety chain and rotatable devices, used on saws or other machines for cutting or abrading material, include a plurality of holding members on which replaceable teeth are retained. Safety lobes prevent the teeth from being dislodged during operation of the saw. The safety lobes may be disposed on a link located in front of the holding member or disposed on a link located in back of the holding member, or both. The teeth can include sharp edges adapted for cutting various materials including wood, plastic and metal and can be formed with abrasive surfaces for abrading materials including brick and concrete. The teeth are quickly removable from the saw without the need for fasteners. While the teeth may be retained by engagement between the teeth and holding member, the chain and rotatable devices may retain the teeth on the holding members using only the safety lobes or safety surfaces. The rotational device can include two blades each including holding members and safety lobes.

Abstract: A disc saw blade includes a saw chain mounted around the circumference of a circular disk, which saw chain is provided with driving links, connecting links and cutting links. Due to the driving links, the chain is guided in at least one chain groove arranged around the periphery of the disk. The bottom of the groove has radial projections distributed around the circumference, and the driving link has a cam surface on a projecting part that projects radially inwards, for interaction with the respective radial projection. The chain can move from a neutral position, in which the respective projecting part is loosely disposed between two adjacent radial projections, to a working position, in which the respective cam surfaces are in contact with the associated radial projections.

Abstract: A safety saw chain for chain saw and more particularly to the configuration of drive links and cutter links so as to get a high cutting power, to decrease the vibration, kickback, and the friction of the saw chain on the guide bar.

Abstract: A saw chain for a power chain saw is provided and comprises drive links and side links that connect them, whereby alternatingly disposed on one and the other longitudinal side of drive links, in place of a side link, are a cutter link and a leading safety link. The cutter link has a cutter tooth and a leading depth limiter, whereby the safety link is provided with a projecting nose for support against the base of a cut. The nose extends in the direction toward the depth limiter. The safety link is provided with a side portion disposed in front of the nose. The side portion has an elevated contact surface, which, when the saw chain is curved in the reversing region, is disposed on the path of a top cutting edge of the cutter tooth, and when the saw chain is extended reaches at least nearly to the height of the depth limiter.

Abstract: A saw chain for a motor-driven chain saw (1), including for a harvester for the lumber industry, is formed from center drive links (10) and lateral connecting links (11). The drive links (10) and the connecting links (11) are pivotally connected to each other via rivets (9). The connecting links (11) are configured, in part, as cutting links (14). These cutting links include a cutting tooth (15) and a forward running surface (16) and a rearward running surface (17). The forward running surface (16) is approximately at the elevation of the leading rivet opening (12) and the rearward running surface (17) is approximately at the elevation of the trailing rivet opening (13). The rearward running surface (17) is configured extended in a direction opposite to the running direction (8) of the saw chain (5). A first radius (18) is the maximum distance of the axis (22) of the leading rivet opening (12) to the region (19) facing toward the forward running surface and lying in the running direction.

Abstract: A high speed harvester cutting chain has increased cutter height to provide an increased space for removal of the cut material from the saw kerf. The increased height of the cutter links eliminates the compacting of the material cut away by the cutter links between the saw chain and the base of the saw kerf. The foot of the cutter links are flared outward to contact the guide bar rails at a different position than the tie straps to increase the wear life of the guide bar and saw chain.

Abstract: A saw chain is automatically sharpened during use by causing top sides of the cutter links to be pressed against a stationary abrasive block when the saw chain is running around a rim type sprocket. The cutting link includes a cutting edge, and a depth gauge recessed radially from the cutting edge by a distance defining the cutting depth. The generally cylindrical outer periphery of the drive sprocket has raised steps or ramps formed thereon which lift the front end of the cutter links relative to the rear ends, thereby allowing a sufficiently large cutting depth to be achieved without locating the depth gauge far in front of the front rivet. This reduces vibration and instability of the saw chain when sawing.

Abstract: A saw chain made according to the present invention includes cutter teeth having a single slicer. Sequentially, the cutter tooth having a slicer on the left-hand side is followed by a raker tooth having an open face on the left-hand side. A cutter tooth having a single slicer on the right-hand side is followed by a raker tooth having an open face on the right-hand side. The wood is cut sequentially by the left-hand slicer, the raker tooth having an open face on the left-hand side, the right-hand slicer and the raker tooth having an open face on the right-hand side. The particular sequence of cutting provides a fast and smooth cut that avoids binding in the kerf. Alternatively, the cutter tooth having a single slicer on the left-hand side may sequentially follow a cutter tooth have a single slicer on the right-hand side. A raker tooth having a full-width raker may follow the sequential cutter teeth or two raker teeth having respective half-width rakers may follow.

Abstract: A chain guiding rail for use in power chain saws has a tip part defining an arcuate run-in section extending from an end point of a forward-run section to the vertex of the tip part, and a run-out section extending from the vertex point to a start point of a return-run section. The run-out section has a substantially larger diameter and a tangential line at its center point forms an angle (b8) of 40.degree. to 70.degree. with a center axis of the rail. To eliminate kickbacks during operation of the chain saw the vertex is situated in a sector of the tip part which is delimited by reference line coinciding with the center axis or extending in parallel thereto, a perpendicular line relative to the forward-run section at the end point (E) and to the parallel reference line or the center axis, and an arc whose center of curvature coincides with the point of intersection of the parallel reference line with the perpendicular line.

Abstract: A hay bale cutting chain with each pair of side links including a cutting link. The chain is without any protrusions other than the cutter portions, e.g. depth gauges and bumper portions are eliminated. The cutting edge, from a side view, is substantially vertical, and the side plate configuration is otherwise without a hook angle. The top plate is terminated short of the chain's mid-point to allow long strands that can get trapped under the top plates of the cutting links to escape. The chain is a small pitch chain, e.g. three-eights inch pitch, and drive at a rapid speed so that small bits are removed that more closely simulate sawdust than wood chips as in typical wood cutting.

Abstract: A center drive cutter chain for mounting on a cutter bar. The chain comprises center drive cutter links having forward and rearward pivot openings and pairs of oppositely disposed side links pivotally interconnected by pins to the cutter links and alternating non-cutter drive links. The side links each have forward and rearward pivot openings and forward and rearward bar engaging undersides. For the side links following a center drive link, the width of each side link between its forward pivot opening and forward bar engaging underside is less than the width between its rearward pivot opening and rearward bar engaging underside. When the axes of the pins extending through the pivot openings of the cutter links and following side links are substantially in a plane, the forward bar engaging undersides of the side links are spaced apart from the adjacent side rails of the bar.

Abstract: A sawchain designed for resharpening while it is idling around the drive sprocket has cutting links (16) on the left and right sides with depth gauges (10) and spade-shaped cutters (22) which between their front (12) and rear borders (14) have a fold (13) substantially perpendicular to the lengthwise direction of the sawchain with the concave side outwards away from the central plane, permitting the rear border (14) and the side edge (12) to contact the side walls of the kerf. The depth gauge (10) is placed so far forward on the cutter links (16) that the chip thickness (19) is sufficient when the sawchain is straight. The intermediate drivelinks (21) may be provided with raker teeth (17) located so far to the rear that they do not touch the bottom of the kerf when the chain is straight, but only loosen and convey the chips cut by the cutters (22) of the cutter links (16).

Abstract: A cutting link for a saw chain useful in heavy workload operations includes spaced-apart longitudinally-extending planar side portions adapted to straddle a guide bar support and a cutting element mounted on one of the side portions and extending toward the other side portion, the side portions being connectable to other links in the chain. A cross piece interconnects the side portions forwardly of the cutting element. The cross piece forms with the side portions a continuous U-shaped zone which defines a depth gauge to determine the depth of cut of the cutting element. A depending nose tab integral with the cross-piece serves to close off a portion of the forward open channel between the planar side portions to minimize accumulation and packing of sawdust under the U-shaped zone.

Abstract: A lightweight disposable cutting chain for use with small, compact power supplies comprises in one embodiment a series of links formed of wire. On certain links an end of the wire loop forming the link is cut to form a sharp edge capable of shaving material, such as wood, being cut. The links are arranged so that a narrow kerf is first cut by the links, other links being formed with cutting edges to shave material and widen the kerf. In other embodiments some or all of the links comprise metal plates formed by stamping from sheet metal.

Abstract: A chain saw blade having a plurality of linked cutting segments having serrated or saw teeth on the cutting edge is provided with depth-control surfaces parallel to the plane of the peaks of the teeth to limit the depth of penetration of the teeth. At the leading end of the leading depth-control surface there is a canted portion which slopes to the end edge of the segment to a point essentially coincident with the plane of the valleys of the teeth.

Abstract: A brush cutting blade having a curved slitter type/non-raker type primary cutting tooth and a preceding appendage forming a combination depth gauge and small stem slitter. The primary tooth terminates over the blade body with the cutting edge provided by that curved portion of the tooth between its most lateral point and the point of termination over the blade body. The cutting edge is curved but outwardly directed in a slitter configuration throughout its length. The lateral point of the cutting edge determines the kerf width to prevent binding. The slitter cutting edge of the appendage is hook shaped to cut small willowy-type stems and the appendage has an upper inclined guide edge that guides the larger rigid-type stems into the primary cutting tooth. The uppermost point of this guide edge of the appendage provides a depth gauge for the primary cutting tooth.

Abstract: A side cutter tooth includes an element having a tip which extends upwardly substantially parallel to the plane of the body. Improved performance is achieved by designing the inner surface of the cutter tip to reduce "clearance" or to create "interference."A single-element side cutter tooth for scoring only one side of a kerf is also described.

Abstract: A saw chain has pivotally interconnected chain links which includes cutting links and safety links and these links are effective as working links. The cutting links are each provided with a cutting tooth for cutting into wood and the safety links are each provided with a projection which limits the depth of the cut of the cutting tooth which follows the safety link. The pivot axes of the chain links lie in an action plane above the guide bar in the stretched portion of the saw chain when the latter is subjected to the pulling force exerted by the drive of the chain saw. The cutting links are pivotable with respect to this plane. In addition, the safety links can also be pivotable in this manner. When the cutting links are in their pivoted-out position under this pulling force, no clearance angle is available at the roof of the cutting tooth so that the cutting edge has no cutting effect. For this reason, there is no kickback when the saw chain is placed against the wood.

Abstract: With motor-driven chain saws, there is the danger that the chain saw will be thrown upwardly and rearwardly when it is applied to wood by the user with a forward thrust. Serious injuries can then occur. The invention is directed to a saw chain which is so configured that the cutting forces are automatically reduced in response to the occurrence of excessive reaction forces so that the reaction force is immediately reduced to a tolerable amount thereby eliminating the kickback effect. The drive links of the saw chain which engage into the nose sprocket of the guide bar are so dimensioned that they can further pivot in the tooth gaps of the nose sprocket out of their normal position and, in this way, take the cutting links with them in such a manner that the free angle .alpha. of the cutting teeth is reduced.

Abstract: An improved cutter chain construction for a bottom unloader of a storage structure. A cutter arm is mounted for rotation about the center of the storage structure, and an endless chain travels in an endless path on the cutter arm and carries a plurality of cutting members or hooks that are mounted at spaced intervals along the length of the chain. Each cutting member has a relatively thin body with a sharp leading edge and an outer enlarged head. The cutting members are mounted in a sequence along the length of the chain. A first cutting member in the sequence extends laterally outward from the chain and is disposed in a first plane, while the next succeeding cutting member lies in a second plane disposed at an acute angle to the first plane, whereby movement of the cutting members through the stored material will cut a wedge shaped mass.

Abstract: An automatically sharpenable saw chain cutting link having primary and secondary depth gauge elements. The primary depth gauge element controls the penetration of the top plate cutting edge into a kerf and is positioned a greater distance forward of the center of the cutting link than the top plate cutting edge is rearward of the center of the cutting link as required for automatic sharpening. The secondary depth gauge element is positioned adjacent the side plate cutting edge in the front to back and lateral directions but below the top plate cutting edge to avoid interference of the automatic sharpening function.

Abstract: A chain saw having a bar (51) with a sprocket (50) rotatably mounted in the nose, and a chain with cutter links (52) mounted to travel along the periphery of the bar (51). The driving tongues (54) of the chain and the gullets (50a) between the teeth of the sprocket (50) being shaped so that when they interfit as the chain passes around the nose of the bar, the rear end (6) of each cutter link (52) is raised relative to cutting edge (67) so that said rear end (6) follows a path about the sprocket (50) outwardly of the path travelled by the cutting edge (67).

Abstract: A gulletless saw chain having a cutting link with a cutter portion that is configured to be top sharpenable. A depth gauge portion is positioned in close proximity to the cutting edge corner of the cutter portion. The depth gauge is laterally offset to position the outer most edge of the depth gauge at the corner of the cutting edge to thereby control side penetration as well as depth penetration of the cutting edge. A drive link preceding the cutting link includes a guide portion with an inclined leading edge that corresponds with the leading edge of the depth gauge. A shallow V shaped opening is formed between the depth gauge and drive link guide portion to assist the cutting link in tracking in the kerf.

Abstract: A side cutter tooth 10 or other chain saw tooth includes a tip 36 which extends upwardly substantially parallel to the plane of the body 24 or which is inclined inwardly at an angle of 0.degree.-50.degree. towards the angle of the body 24 to create improved resistance to crimping and breakage of the cutter element 34 of the tooth 10 so that the tooth will not deflect outwardly when exposed to a downward force, such as often experienced during a bind or pitch. Protection of the tooth 10 is also provided by including at least one corrugation 42 in the vincinty of the curl outwardly from the body 24 to reinforce this curl and to further reduce crimping and breakage. That is, the corrugation 42 includes a stamped portion of the link 20 or 22 spanning the intersection of the cutter element 34 with the body 24.

Abstract: The invention is directed to a saw chain for a power-driven chain saw. The saw chain includes a plurality of cutting links, a plurality of connecting links and a plurality of driving links. The links are interconnected by rivets to define the saw chain. The cutting links include a cutting tooth and a rearward foot defining a tilt edge. The cutting link tilts about the tilt edge when the cutting tooth penetrates the wood to be cut. In tilting about the tilt edge, the cutting edge of the cutting tooth is raised from a first elevation to a second elevation and the difference between these elevations is the tilt displacement. The tilt edge lies in a vertical plane which is perpendicular to a traverse plane containing the axes defined by the forward and rearward openings for the linkage rivets connecting the cutting link to the rest of the saw chain.

Abstract: An anti-kickback saw chain having a drop-away articulated depth gauge link preceeding each cutting or fibre removing link in a link sequence utilizing V-shaped cutter tooth links, each followed by a generally L-shaped raker tooth link. The depth gauge surface of the depth gauge link is spaced forwardly of the cutting tooth and the trailing edge thereof is located aft of the pivotal connection with the cutting tooth link when the pivot points of the links are aligned. The depth gauge link is designed to maintain cutting efficiency on the bar nose and to "drop away" from the kerf when an obstruction is encountered and to initiate a depth gauge restoring action with the associated cutting tooth so as to avoid jamming or locking of the chain and attendant kickback.

Abstract: A saw chain includes a non-cutting guard link having a base with rivet-receiving openings, and a top portion with a nose extending rearward of the base portion. The nose is formed by coining, rolling, or bending, such as in a progressive die system, so that the width of the nose is approximately equal to the width of the base portion of the guard link plus the width of a center link to which the guard link is pivotally connected. Right-hand and left-hand cutter links follow, respectively, left-hand and right-hand guard links, the guard links cooperating with the cutter link depth gauges to present a facial area approximately equal to the chain width to thereby minimize kick-back.

Abstract: An anti-kickback saw chain including a cutter link having a cutter portion which includes a shoulder located rearwardly of a cutting edge at the forward end of the cutter portion.

Abstract: To provide better performance for a saw chain by enhancing the life and performance of side cutter teeth, this invention discloses a novel side cutter tooth which includes a cutter element having either a continuously curved portion attached to the body of the cutter tooth or a substantially straight portion extending outwardly from the body of the tooth. The continuously curved portion or substantially straight portion causes the cutter element to bend substantially at the intersection between the body and the cutter element when the cutter element is exposed to inwardly directed forces which tend to flatten the curved or substantially straight portion out of its half-space into the plane defined by the body of the cutter tooth. Removal of the complex curve ordinarily used in the center-mounted cutting teeth of saw chain greatly enhances the performance of the cutting teeth, reduces breakage of the teeth, and improves the efficiency of a saw chain using the improved cutting teeth.

Abstract: An anti-kickback saw chain including a series of left and right cutter links disposed alternatively on opposite sides of the chain. A novel safety link disposed in front of each cutter link functions to prevent a cutter portion in the cutter link, when rounding the nose of a saw bar, from cutting deeply into the wood. The safety link includes a leading projection adjacent the forward end of the link and a trailing projection adjacent the rear end of the link, the leading and trailing projections being separated by a gullet intermediate the projections.

Abstract: A saw chain for chain saws, particularly portable power chain saws, comprising chain members which are pivotally connected with each other. At least some of the chain members are provided with a safety marking to show the extent of wear.

Abstract: A cutting attachment for a chain saw which substantially reduces the problems of kickback, lubrication and maintenance, is described. The attachment comprises a guide bar, a saw chain and a drive sprocket. The guide bar is smoothly and symmetrically convexly curved along both its longitudinal edges with a first radius of curvature and is provided with a nose portion with a second and smaller radius of curvature. The edge of each of the cutter and balancing links in contact with the bar is provided with two curved surfaces, one surface having a radius of curvature corresponding to the radius of curvature of the nose portion of the bar, and the other surface having a radius of curvature corresponding to the radius of curvature of the longitudinal edge of the bar. The height of the cutter links is chosen in relation to the length of the cutter to prevent rearing of the cutter links.

Abstract: To reduce the possibility of a kick by a chain saw when cutting on the end of the bar, this invention provides cutter elements having spurs to cock the elements when the elements engage the idler sprocket on the end of the bar. As the elements begin to move in an arc around the idler sprocket, the spurs ensure that the leading depth gauge of the element does not fall away to expose the trailing teeth to too great a depth of cut. Instead, at any position in the arc, the spurs ensure that the depth between the depth gauge and the tooth of each element remains substantially no greater than the depth between the depth gauge and the tooth when the element is moving in a straight line. Preferably, the spur cocks the element so that the depth gauge is effectively higher than the tooth (i.e., the radius of the arc of the outside edge of the depth gauge is larger than the radius of the arc of the outside edge of the tooth).

Abstract: A saw chain includes a cutter link having a depth gauge with a rearwardly and upwardly sloping edge, and a guard link having a top edge generally paralleling the bottom of the kerf being cut by the saw chain. The guard link is further provided with a steep forward edge inclined upwardly and rearwardly toward the said top edge, and a rearward edge inclined upwardly and rearwardly wherein the rearward most portion of the guard link adjacent the following cutter link depth gauge is beneath a line extending between the top of the cutter link's cutting tooth and the peak of the depth gauge.

Abstract: A saw chain, for motor chain saws, provided with depth limiters, gauges, or members, and with cutting teeth respectively arranged, in the direction of cutting movement, behind a depth limiter. Each cutting tooth projects outwardly from a base body transverse to the direction of cutting movement of the saw chain, and is set or twisted relative to the plane of the base body, with each cutting tooth having a transverse cutter which is formed by a cutting back surface and an outer surface of the twisted cutting tooth. Each depth limiter is bent laterally out of the plane of the base body of the subsequent cutting tooth, and forms a rearwardly open, acute inclined or chamfered angle with this plane. This angle may range between 3.degree. and 20.degree., and is preferably 9.degree.. The leading region of the depth limiter may be provided with a continuously and uniformly curved, downwardly extending, rounded entry portion.

Abstract: An improved, endless safety saw chain includes a pair of side links, one of the side links being a cutter link and the other of the side links being a noncutting link and having a depth gauge in substantial alignment with a depth gauge on the cutter link. A preceding center drive link may include an upward and rearward sloping surface positioned to extend between the depth gauges of the side links. The sloping surface is preferably dimensioned so as to be in substantial alignment with the depth gauges as the saw chain articulates about the nose of the chain saw bar.

Abstract: A cutting saw chain having cutting tooth links distributed therealong. Each cutting tooth link having a portion at one end upstanding therefrom and twisted out of the plane of the link to form a cutting edge. The links on opposite sides of the chain have the upstanding portions twisted in opposite directions. Each cutting tooth link at the other end has a portion upstanding in the plane of the link and forming depth limiting means. A link in advance of each cutting tooth link also has an upstanding part forming a depth limiter for the following cutting tooth link.

Abstract: A saw chain assembly which requires a minimum of independently moving elements is disclosed in which the assembly includes a plurality of cutter links interconnected in the form of a chain by linking members. Each cutter link preferably comprises a unitary gear and cutting element. Each linking member comprises two substantially parallel side walls which are integrally connected by a bridge wall so as to form a channel between the side walls. The ends of adjacent links are disposed in the channel and hingedly connected to the side walls.

Abstract: A saw chain for a chain saw with kerf sidewall cutting, free end chisel raker teeth having positive cutting edge rake angles and with bifurcated cutters formed from paired, laterally opposed cutting elements wherein the free end chisel corners of the raker teeth project laterally outwardly beyond the bifurcated cutter forming elements so that the combined cutting width of two mirror image raker teeth is greater than the cutting width of the bifurcated cutters; the height of the bifurcated cutters being generally equal to or less than the height of the raker teeth; the cutting edges of each raker tooth and each bifurcated cutter being disposed rearwardly of the rearmost pivot point of the link which bears it, and the outer surfaces of the shank portions of the raker teeth and the outer surfaces of the bifurcated cutter forming elements being formed to engage the upper edges of the immediately following side links to lock each cutter bearing link against rearing back more than a specified amount.