Abstract: A saw chain is disclosed which includes cutting links having a central pivot on the bottom or inner edge of such cutting link which contacts the track of a saw bar on which the chain is mounted. A front foot portion and a rear foot portion which extend from the central pivot to the front end and the rear end, respectively, of the cutting link are normally spaced from such track when it is not cutting. The cutting link tilts about the pivot rearwardly and forwardly during cutting to provide a smooth rocking motion which reduces vibration and injury to the operator. One embodiment of the cutting link employs a single pivot located centrally between the front rivet opening and rear rivet opening. Another embodiment of the cutting link employs two pivots which are spaced apart and are both located centrally between the front and rear rivet openings. The saw chain includes side cutting links and side tie strap links connected by rivets to central drive links.

Abstract: A sprocket assembly including a sprocket adapter driven by the motor of a chain saw. The adapter includes an adapter shaft which has a defined inner opening to fit around the drive shaft of the chain saw. A sprocket is mounted on the adapter shaft. Splines on the adapter shaft exterior fit into spline grooves of the sprocket. The thickness at the roots of the splines provide the strength to resist breakage. The exterior areas of the adapter shaft between the splines are flat landings which define relieved thickness areas between the splines and are aligned with tang-receiving pockets in the sprocket. The relieved areas permit an optimum sizing of the sprocket to the saw chain with sufficient pocket depth to fully receive the drive tangs of a saw chain. The sprocket rims are provided with mated inner edges that mate to the flat landings of the adapter shaft to facilitate transmission of the turning power from the drive shaft.

Abstract: A hook angle gauge having a bar with a straight bottom edge that lays across the cutting corners of successive cutting links in a length of saw chain. A face plate includes a series or row of holes or openings that simulate the cross section of the file used to sharpen the cutting links. Different height placements of the openings relative to the bar edge indicate different hook angles. An operator slides the face plate across a selected cutting link side plate until an opening therein matches the configuration of the side plate cutting edge. Each opening is marked with the hook angle setting indicated by that opening to enable the operator to determine the cutting link's hook angle.

Abstract: A cutting link having a cutter portion and a depth gauge. And a guide edge extending between the depth gauge peak and cutter portion for guiding a file to sharpen the cutting edge of the cutter portion. In the process of sharpening the cutting edge, the cutter portion is abraded away along a line that furthers the guide edge and thereby continues the guiding of the file to properly file the cutting edge.

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.