521B Track Felller Buncher

521B Track Felller Buncher

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.

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Gross Power

Operating Specifications

Max Reach w/ Attachment


Operating Weight w/o Attachment

Service Refill Capacities

Cooling System
Engine Oil
Hydraulic System
Swing Drive
Fuel Capacity

Hydraulic System

Electric hydraulic oil fill pump
Dedicated variable displacement pump for travel circuit - 200 cc
Dedicated variable displacement pump for boom and implement functions - 200 cc
Dedicated variable displacement pump for saw motor - 55 cc

Tractive Effort


Boom System

Track Feller Buncher - Lift over front of tracks: Bare Pin Lift @ Maximum Reach (without head)
6100 kg @ 6.2 m (13,500 lb @ 20 ft 6 in)
Track Feller Buncher - Lift over front of tracks: Maximum Reach (with head)

Power Train

Engine Model
Cat® C9 ACERT™
Gross Power
Gross Power @ 1,800 rpm
Rated Power @ 2,100 rpm

Track Length

Track Length

Ground Clearance

Ground Clearance

Track Gauge



Cab meets FOPS/OPS/ROPS/WCB/OR-OSHA requirements

Operating Weights (without heads, standard counterweight)

Track Feller Buncher - 521B


330 EX (D7)

Standard Equipment

  • Electrical
    • 24 volt electrical system
    • Two 12 volt maintenance free batteries with 950 CCA
    • 95 Amp alternator
    • IQAN programmable controls
    • MD3 monitor display screen
  • Guards
    • Hydraulically actuated hinged engine enclosure with warning alarm
    • Engine fan guard
    • Bottom guards
    • Isolation mounted cab and engine
    • Heavy duty radiator guard door
  • Operator Environment
    • OPS/FOPS/ROPS/WCB/OR-OSHA certified cab
    • Dual joystick control
    • Reverse slope windshield
    • Air ride seat
    • Skylight - alternate escape hatch
    • Top escape hatch
    • 76.2 mm (3 in) retractable seat belt
    • DIN mount radio ready with speakers
    • Operator sound suppression to standards
    • Travel alarm
    • Cup holders (2)
    • Two 12 volt and one 24 volt power outlets
    • Front window, 32 mm (1.25 in) thick Margard
    • Positive filtered ventilation, pressurized cab with bi-level air conditioner, heater and defroster with manual control
    • Left side fresh air window with screen
    • Forced air fan
    • Washable floor mat
    • Neutral lever (lockout) for all controls
  • Power Train
    • C9 ACERT engine meets U.S. EPA emission standards
    • Variable travel speed (3 ranges)
    • Under hood primary air filter
    • 43° C (109° F) degree ambient temperature cooling package: - Aluminum core ATAAC and side-by-side radiator and oil cooler - Removable debris screen - Swing out A/C condenser
    • Electric fuel priming pump
    • Fuel water separator
  • Undercarriage
    • Track roller guards with access holes
    • Hydraulic track adjusters
    • Double flange track rollers
    • GFT80 Lohmann final drives
    • Cat 330 size undercarriage components
    • Nine (9) track rollers and two (2) carrier rollers per side
    • Welded, non-leveling carbody
  • Hydraulics
    • Dedicated fixed displacement pilot pump
    • Dedicated variable displacement pumps for track and implement functions
    • Variable displacement saw pump for feller buncher hydraulics only
    • 325 EX swing drive and swing motor
    • Electric hydraulic oil fill pump
    • High flow hydraulic arrangement for felling heads with two cylinder arm design 180 L/min (48 gal/min)
    • Low flow hydraulic arrangement for felling heads with single cylinder and link design 120 L/min (32 gal/min)
    • 265 L (70 gal) hydraulic tank
  • Antifreeze
    • 50% concentration extended life coolant
  • Other Standard Equipment
    • Heavy duty hood enclosure
    • Flexxaire fan
    • Vandalism protection
    • Spare hose storage area
    • Grease gun bracket and storage area
    • 856 L (226 gal) fuel tank

Optional Equipment

  • Linkages
    • Intermittent
    • Feller Buncher
    • Omission - Linkage
  • Hydraulics
    • Intermittent
    • Feller Buncher - Low Flow
    • Feller Buncher - High Flow
  • Felling Heads
    • HF201B*
    • *Heads available with Full Tilt 330 degree, or Partial Tilt 40 degree
  • Track Systems
    • 610 mm (24 in) SG pads, clipped corners, with mud/snow reliefs
    • 711 mm (28 in) SG pads, clipped corners, with mud/snow reliefs
    • 711 mm (28 in) DG pads, clipped corners, with mud/snow reliefs
    • 914 mm (36 in) Tri-track, clipped corners, with mud/snow reliefs
    • Star Carrier Rollers
    • Standard Carrier Rollers
  • Other Equipment
    • Lighting Gp-HID, replaces certain standard lights
    • Heavy Counterweight
    • Starting Aid, Cold Weather - includes two additional batteries
    • Starting Aid, Arctic - includes engine and hydraulic oil Arctic heater
  • Field Installed Attachments
    • Skylight, peaked, removable