The new B Series track feller bunchers feature smoother hydraulic performance, increased engine HP, a more comfortable operator station and better right side operator visibility. The Cat 521B Series are zero tail swing machines designed for medium to high production clear cut and or select cut on rough terrain. These machines perform in a variety of small through larger tree size applications. A robust undercarriage utilizes proven components, customized for demanding forestry conditions. The unique boom design provides industry leading lift capacity throughout full reach range, a benefit in large timber.