HARVESTER HEADS
harvester or felling head. It combines the basic cutting tools necessary such as knives and in- feed rollers with not only sophisticated hydraulics but also computerised control systems to optimise the cut. Of greatest importance in this
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year’s technology review is the robustness of the heads, with an increased emphasis placed on protecting the system components while still ensuring the stem is not damaged. This is a delicate balancing act and one on which Waratah in particular has spent a lot of time working. One of the most striking innovations on this front comes from Cat, which has installed electronics and valves away from the head to protect them from the usual wear and tear that comes with operating at the front of the machine.
Another major focus was on flexibility. This is a direct result of the economic situation that has required contractors to switch quickly between multi-stem harvesting and larger, single-tree jobs where speed is more of a priority. This year’s heads have more options and this has been combined with quick installation and change-overs. Finally, the more boutique suppliers have seen a necessary switch to eucalyptus and, to a lesser degree, tropical wood harvesting. This is a response to the growing markets of the Southern Hemisphere.
Caterpillar harvester heads are field proven in Europe, Russia, North America and South America and can be customised with a variety of feed roller motors — high speed to boost productivity or high torque for the delimbing power necessary for large or ‘limby’ trees.
The PF-48, a fixed 4-roller head with up to a 610 mm cutting diameter and feed speed of 4.3 m/second, is designed for select thinning or where more control of the head is required. The 4-roller design gives the head more contact with the tree for better feeding and more torque than a two-roller head. The hydraulics and valve body are mounted on the carrier — not out on the head
ne of the most advanced pieces of technology in the logging game is the
oil. This increases the service life of the bearings and the measuring wheel.
The PE-44, a dangle head for working in softwood and small to medium hardwoods, has a cutting diameter of up to a 650 mm and feed speed of 5 m/second. It features the Dasa4, a simple, cost effective control system that is matched with three measurement encoders to provide accurate length and volume readings. The Dasa4 comes standard with a program to optimise log lengths and achieve the most value for every harvested tree. “When a tree is cut, the Dasa4 calculates the height and taper based on the species, diameter at the butt and data gathered from other trees cut in the vicinity. With this information and the logger’s cutting list, the computer calculates what logs to take from that tree to maximise profitability,” Schmidt said. The PE-44 is also versatile. “Independent feed roller and knife pressure settings for six different species give loggers the ability to switch between softwood and hardwood with just a touch of a button. The pressures are automatically changed providing the highest quality product for each species.” The PE-44 features a compact,
The Cat HF201 felling head
Not having the electronics or valves on the head makes the head more reliable and increases the uptime – no other major head manufacturer makes a fixed head quite like this – Cat’s Justin Schmidt
getting slammed into the ground and taking the abuse. “Not having the electronics or
valves on the head makes the head more reliable and increases the uptime,” Justin Schmidt, Caterpillar’s Product Specialist for harvester heads, said. “No other major head manufacturer makes a fixed head quite like this.” Other features add to the
head’s robustness: the knife cylinder pin anchors into the
30 International Forest Industries | AUGUST/SEPTEMBER 2011
frame, dissipating the stress that could cause cracking in the knife cylinder mounting. The thick saw cover reduces the chance of damage from falling limbs, and the structure was designed to prevent wood chips and debris from funnelling inside. The Independent Measuring Device (IMD) ball bearings are sealed, so even if the cover on the measuring wheel gets loose or is punctured, the IMD will not lose
well-protected mono-block valve design. Most functions are contained in one main manifold, eliminating the constant leaking between valve sections found on many competitive heads. “This design also makes it easier to do repairs,” Schmidt added. “A lot of competitors use a sectional valve design, which means that if you have a problem with the upper
The Cat PF-48
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