Patent ID: 7882865

Claim:
A boom unit for a tree processing machine having: a boom with a square cross-section; a boom support in the form of a straight sleeve; front boom mounting means at the front end of the sleeve and rear boom mounting means at the rear end of the sleeve, the boom movably mounted through the sleeve and the front and rear boom mounting means and positioned to have a corner of the boom on the bottom and an opposite corner of the boom on the top directly over the bottom corner; the front mounting means having a pair of front, bottom rollers arranged in a v shape to cradle the boom; the front mounting means having a top guide wheel rotatable on a horizontal axis above the bottom rollers and centered with respect to the bottom rollers, the top guide wheel having a groove in its periphery to ride on the top corner of the boom to hold the boom against the bottom rollers; the rear boom mounting means having a pair of rear, top rollers arranged in an inverted v shape riding on the top portion of the boom, a bottom guide wheel rotatable on a horizontal axis below the top rollers and centered with respect to the top rollers, the bottom guide wheel having a groove in its periphery receiving the bottom corner of the boom, the rear top rollers holding the boom against the bottom guide wheel and boom moving means for moving the boom relative to the boom support, the boom moving means having a single cable generally mounted above, and spaced from, the boom with the ends of the cable attached to the upper ends of the sleeve, the cable passing over cable guide means at the ends of the boom, the cable passing above the sleeve through a cable drive unit, the drive unit mounted on the top of the sleeve and spaced from the boom.