Patent ID: 7959169

Claim:
An oscillation joint, comprising: a stationary frame member configured to rotatable support a first drive sprocket; an oscillating frame member configured to support a second drive sprocket and rotate about the stationary frame member, the first and second drive sprockets being aligned along a plane; a drive chain extending about the first and second drive sprockets; a first thrust washer located between a first surface of the stationary frame member and a substantially parallel first surface of the oscillating frame member; a second thrust washer located between a second surface of the stationary frame member and a substantially parallel second surface of the oscillating frame member, the second thrust washer disposed substantially parallel to the first thrust washer, wherein the first and second thrust washers are located substantially symmetrical with respect to the plane; a first wear sleeve, wherein the first wear sleeve is substantially perpendicular to the first thrust washer; and a second wear sleeve disposed substantially perpendicular to the second thrust washer and substantially parallel to the first wear sleeve, wherein the first and second wear sleeves are located substantially symmetrical with respect to the plane.