Chain saw bars

In a chain saw bar having opposite longitudinal edges each comprising a central longitudinal guide groove and a longitudinal support surface on each side of the guide groove adapted to support a chain as the chain travels about the periphery of the bar, said chain having a plurality of alternate equi-spaced cutter and connector links and a drive link pivotally connecting each cutter link to the adjacent connector links, said cutter and connector links each having inner edge faces that slidably engage the support surfaces of the bar and each drive link having an inwardly extending tongue that is received in the guide groove, the improvement comprising an extension at the forward end of the bar,

• a discal member located on each side of said extension and rotatably supported thereby for rotation about an axis transverse to the bar, said extension and discal members defining a groove along which the tongues of the drive links travel as the chain passes around the forward end of the bar, said extension forming the base of said groove and being contoured so that the tongues of the drive links are in contact with the said base of the groove as the chain passes from the discal members to the bar, and so that the links of the chain onto the bar are raised clear of the bar as the chain passes from the discal members to the bar.

In a chain saw comprising a chain saw bar having opposite longitudinal edges each comprising a central longitudinal guide groove and a longitudinal support surface on each side of the guide groove, and a chain adapted to travel about the periphery of the bar, said chain having a plurality of alternate equi-spaced cutter links having a cutting edge, connector links, and a drive link pivotally connecting each cutter link to the adjacent connector links, said cutter and connector links each having inner edge faces that slidably engage the support surfaces of the bar and each drive link having an inwardly extending tongue that is received in the guide groove, the improvement comprising:

• a support member mounted on one end of the bar for rotation in the plane of the bar,
• a peripheral edge on said support member to support the chain as it passes from one edge of the bar to the opposite edge, said peripheral edge of the support member being constructed to guide the pivot points of the cutting links on a circumferential path of a first smaller radius and the pivot points of the connecting links on a circumferential path of a second radius, said first radius being smaller than the second radius whereby kickback of the chain saw is minimized.