Stroke Delimber Product

Overview

The stroke delimber is a mobile log-processing machine designed to debark and limb logs at remote stump locations without transporting them to a central mill. It combines a tracked or wheeled carrier chassis with a telescoping Telescoping Boom that positions hydraulic delimbing Delimb Arms Assembly and a Topping Saw Unit directly over the log. The operator works from an enclosed Operator Cabin, using a proportional joystick to extend the boom, open the limbing arms, and activate the topping saw—all in a single work cycle.

Stroke delimbers enable integrated harvesting operations where logs are processed in-place and trucked directly to the mill as debarked stems, eliminating the cost and labor of secondary processing. They are particularly valuable in tropical hardwood operations and certified sustainable forestry where on-site processing minimizes handling and transit damage.

How it works

The operator controls the delimber from the enclosed Operator Cabin using a proportional Control Joystick. The diesel Diesel Engine drives a variable displacement Hydraulic Pump supplying 280 bar through a Valve Manifold proportional manifold.

To process a log, the operator drives the tracked carrier to position the machine alongside the felled stem. The Boom Base Turntable turntable rotates the entire boom assembly (via proportional pilot pressure to a boom rotation motor), orienting it over the log. The operator then actuates the Lift Cylinder, raising the Telescoping Boom boom, and activates the Extend Cylinder, telescoping the Inner Boom Section section to extend the boom tip over the log.

At full extension (14 m reach), the Delimb Arms Assembly assembly is positioned over the log. The operator engages the Arm Motor, oscillating the Left Delimb Arm and Right Delimb Arm arms back and forth at 30–60 cycles per minute. Each arm is fitted with three hardened Delimb Knife knives mounted in Knife Holder Block blocks along the Arm Beam. As the arms stroke, the knives shear off branches where they meet the main stem, and the severed limbs fall away from the machine.

The delimbing process takes 2–5 minutes per log depending on branch size and density. Once delimbed, the operator retracts the arm motor and engages the Topping Saw Unit, positioning the chainsaw or bandsaw blade at the log's crown (base of branches). The Saw Motor spins the Saw Chain at 2000 rpm, and the operator actuates the Saw Feed Mechanism proportional cylinder, feeding the saw downward to sever the crown. The cut log is now debarked and limbless, ready for trucking.

The operator then retracts the boom (both lift and extend cylinders) and drives the machine to the next log. A skilled operator can process 6–12 logs per shift, depending on log size and site conditions.

Boom and Arm Design

The Telescoping Boom is a two-stage telescope boom: the Outer Boom Section is a fixed 6 m section with a 50 mm pivot pin, while the Inner Boom Section telescopes 4 m into it for a maximum reach of 14 m. Both sections are seamless steel box tubes with reinforced walls (250×250 mm outer, 220×220 mm inner).

Boom lift is provided by a Lift Cylinder (100 mm bore, 1200 mm stroke), and boom extension via a Extend Cylinder (80 mm bore, 1500 mm stroke). Both cylinders are rated 280 bar and control via proportional spool valves in the valve block. Load-check relief prevents overloading if the boom hits an obstacle.

The Delimb Arms Assembly assembly houses two arms, Left Delimb Arm and Right Delimb Arm, that oscillate around a central Arm Frame pivot. The Arm Motor is a 25 cc/rev fixed-displacement motor driven by a proportional spool valve, producing 30–60 strokes per minute at full flow. Each arm is 1.5 m long and carries three Delimb Knife hardened steel knives spaced 500 mm apart. The knives are replaceable and typically last 200–400 hours of operation before dulling.

Saw and Finishing

The Topping Saw Unit performs the final topping cut, severing the branch crown above the marketable stem. A chainsaw is the most common choice due to simplicity and rapid blade change. The Saw Motor is a small fixed-displacement motor (10 cc/rev) providing 2000 rpm chain speed, adequate for cutting logs up to 700 mm diameter.

The Saw Carriage guides the saw in a vertical path, and the Saw Feed Mechanism proportional cylinder provides automatic feed—the operator modulates pilot pressure to control cut speed, typically 1–2 m/min. A mechanical depth stop can be set to ensure consistent crown removal length (typically 100–200 mm below the branch insertion).

Chassis and Carrier

The Carrier Frame is typically tracked for remote forest accessibility. The Frame Beam is a welded box-section 4.0 m long, connecting the engine mounting pads to the Boom Base Turntable turntable. The Track Drive System comprises a hydraulic final drive motor with a sprocket engaging 20–30 Track Link links, similar to compact excavators.

The Boom Base Turntable turntable allows 360° rotation of the boom, enabling the operator to position the delimber head around the log without repositioning the machine. The slew bearing integrates a pilot-operated rotation motor (typically 60 rpm at full pump flow).

Hydraulic System and Control

The Hydraulic Pump is a variable displacement bent-axis pump with pressure compensation and load-check relief. All operations—boom lift, extension, arm oscillation, saw drive, and track propulsion—are controlled via proportional spool valves in the Valve Manifold manifold, piloted by the operator's proportional joystick.

The Hydraulic Cooler is fan-driven and maintains oil temperature below 50°C during intensive processing cycles. The Hose Set is routed in a protective spiral wrap under the frame.

Performance and Applications

A stroke delimber can process 30–50 tonnes of logs per shift depending on log size and branch density. Processing at the stump eliminates transport to a secondary mill, saving fuel and labor. The debarked and limbless logs can be loaded directly onto trucks, reducing total supply-chain time.

Stroke delimbers are particularly valued in:

• Tropical hardwood harvesting (maximizing stem recovery before transport)
• Certified sustainable operations (minimizing handling damage and on-site waste)
• High-value specialty timber (precision crown removal)
• Integrated harvester systems (boom-mounted on tracked harvesters)

Models from Komatsu, John Deere, and Husqvarna deliver proven field performance in demanding environments.