Feller Buncher Product

Overview

The feller buncher is a tracked harvesting machine designed to fell trees and bunch them for extraction. It combines a rotating saw unit with hydraulic accumulator arms mounted on an articulated boom, allowing the operator to cut and hold multiple trees in a single grip before laying them down in neat piles. Feller bunchers are essential in mechanized forestry operations, reducing labor and increasing productivity compared to chainsaw felling.

The machine comprises a tracked carrier chassis with a diesel engine, hydraulic pump, and boom assembly. The boom rotates ±180° and extends 6–8 m, positioning the Felling Head above target trees. The felling head combines a high-speed Saw Unit with two opposing Left Accumulator Arm and Right Accumulator Arm, forming a clamp that grabs the stem after cutting.

How it works

The operator controls the machine from an enclosed Operator Cabin using a proportional joystick that pilots proportional spool valves in the Valve Block. The diesel Diesel Engine drives a variable displacement Main Pump supplying 280 bar to all circuits.

To fell a tree, the operator positions the machine by actuating the Left Track Drive and Right Track Drive independently, using steering Coupling Block cylinders for articulation. Once positioned, the boom is raised via the Boom Cylinder, extending the cutting head toward the stem. The joystick simultaneously engages the accumulator arm cylinders, closing the gripper fingers around the stem. The Saw Spindle rotates the Saw Blade at 800–1200 rpm, cutting through the timber at the stump.

After cutting, the operator retracts the boom cylinder and arm cylinders, bunching the felled tree with others against the accumulator. The head rotator motor on the Boom Rotator allows the operator to orient the bunched stems horizontally before laying them on the ground. A single feller buncher can bunch 10–15 trees per turn.

Hydraulic pressure is maintained constant by the pump's pressure-compensating swashplate and load-check spool valve. The Cooler Radiator continuously cools the return oil to prevent overheating during intensive cutting cycles. The Hose Bundle carries all power lines from pump to actuators in a single spiral wrap, reducing hose routing complexity.

The tracked chassis provides excellent ground grip on soft or steep terrain. The Track Assemblies are composed of Track Link and Track Pin assemblies, tensioned by floating Track Idler wheels. Each track drive includes a bent-axis Final Drive motor connected to a sprocket, rotating a 12-tooth drive sprocket. Three Bogie Roller sets distribute machine weight across the track.

Saw and Accumulator Design

The Saw Unit is a spindle-driven circular saw delivering a kerf of 4.8 mm, typical for clean conifer cuts. The Saw Spindle is mounted on Spindle Bearing radial bearings and rotates at variable speed up to 1200 rpm. A hydraulic motor on the boom rotates the entire head including the saw, allowing cross-cuts of multiple stems in a single grab cycle.

The accumulator arms use double-acting cylinders (80 mm bore, 1200 mm stroke) that close the gripper fingers against the stem. The Gripper Fingers are elastomer-coated steel pads that grip without marring bark; they return to open via coil springs on loss of hydraulic pressure. A pair of arms provides balanced clamping force of ~120 kN, sufficient for stems up to 800 mm diameter.

Control and Safety

The operator sits in a rollover-protective structure (ROPS) Cab Frame equipped with a suspended Seat Assembly and harness. The Control Joystick outputs proportional pilot signals (4–20 mA) to spool valve stages, giving smooth multi-axis control. Pressure transducers in each pilot circuit provide proportional feedback, allowing precise arm positioning.

A load-check pilot relief in the Main Pump ensures no circuit exceeds design pressure. The large Rotator Bearing (400+ mm bore slew bearing) and articulation Frame Cross-Member are sized to handle reaction forces from felling impact, protecting the boom structure.

Applications

Feller bunchers are deployed in coniferous harvesting (pine, spruce, larch) and hardwood operations. Models range from compact 15 tonne machines for selective thinning to heavy-duty 24 tonne units for clear-cutting campaigns. In tropical regions, smaller models are paired with cable skidding to minimize ground disturbance. A modern feller buncher can harvest 30–50 tonnes per shift depending on timber size and slope.