- Diameter at breast height — stem diameter measured about 1.3 m above ground. The single most important stand figure when specifying a harvester head, because head productivity is a curve against diameter rather than a single number.Optimum vs maximum diameter →
- The diameter band in which a manufacturer states a head is most productive. Distinct from both the recommended maximum regular DBH and the absolute maximum cutting capacity — three different numbers that are routinely conflated.Harvester heads →
- An hour in which the machine is actually producing. Distinct from engine hours, which include idling, and from scheduled hours, which include delays. Costing on engine hours understates cost per unit.Cost of ownership →
- An hour in which the machine was rostered to work, whether or not it produced. The denominator in the mechanical availability calculation.
- Scheduled time lost waiting on a truck, breakdown, fuel, operator, weather, road access or a downstream processing bottleneck.
- Available scheduled hours ÷ total scheduled hours × 100. Raising availability from 85% to 95% is often worth more than a 5% gain in theoretical production, and is usually cheaper to buy.Machine availability →
- The share of available time a machine actually works, and the variable that governs cost per hour more than any other. The same machine costs double per hour at half the annual hours.Machine cost calculator →
- The standard data format for forestry machine production reporting. StanForD compatibility matters commercially because it allows machine-recorded volumes to reconcile against mill measurement.Data and telematics →
- A log grade or product class — sawlog, pulpwood, peeler and so on. A harvester's control system optimises bucking across assortments to maximise stem value.
- Crosscutting a felled stem into logs of specified length and quality, under computer optimisation in a modern harvester.
- The portion of a stem that can be sold, as opposed to total standing volume. Cost per cubic metre should always be calculated against merchantable volume.
- Total machine operating cost divided by production. At $280/hour and 25 m³/hour it is $11.20/m³; at 18 m³/hour it is $15.56/m³ — a 39% increase with no change in hourly cost.Cost per cubic metre →
- The unit that mulching, tilling and establishment work is sold in. At $350/hour, 0.75 ha/hour is $466.67/ha and 0.35 ha/hour is $1,000/ha — which is why vegetation density must be assessed on site.
- The slowest critical stage in a production chain, which sets the whole system's output. Investment anywhere else adds cost without adding production.Bottleneck analyser →
- A cut-to-length machine that fells, delimbs, measures, bucks and sorts in a single cycle, recording production data as it goes.Harvesters →
- Carries cut-to-length logs completely off the ground in a load bunk. Economics reduce to payload per trip multiplied by trips per productive hour.Forwarders →
- Cuts standing trees and places them into bunches for extraction, without processing them into logs. The opening stage of the full-tree system.Feller bunchers →
- Drags stems or logs to a landing rather than carrying them. Faster and simpler than a forwarder, at the cost of more soil disturbance and wood contamination.Skidders →
- Converts whole stems into logs at the landing in a full-tree system — the same function a harvester performs at the stump in cut-to-length.
- The attachment that grips, fells, feeds, delimbs, measures, bucks and sometimes debarks. It contains much of the technology responsible for production, and most of the unplanned downtime.Harvester heads →
- An attachment that grabs, cuts, retains and places a stem, turning an ordinary excavator into a controlled tree-cutting machine.Tree shears →
- Grips the limb or stem before or during the cut and keeps control of the severed section — the attachment for working near buildings, roads, rail and utilities.Grapple saws →
- Penetrates, splits, loosens, extracts and handles a stump rather than grinding it, removing the root mass and creating a potential biomass stream.Stump shears →
- A slow-speed stump reduction system, attractive where high-speed chip projection is undesirable — near glazing, traffic or livestock.
- Reduces standing vegetation to mulch in place. The strongest crossover market between forestry, civil construction and vegetation management.Forestry mulchers →
- Works below the soil surface to destroy root systems, incorporate stumps, break compaction and prepare planting sites. Not an agricultural rotary hoe.Forestry tillers →
- Converts stems, tops and slash into chips. Rarely the bottleneck itself — the feed system and haulage usually are.Whole-tree chippers →
- Reduces dirty, mixed, contaminated or stump-heavy material with hammers rather than knives. The correct machine where a chipper's knives would not survive.Chipper vs grinder →
- An extraction system carrying bunched stems in a clamped bunk, used for very long extraction distances in tree-length systems.
- A tethering system providing controlled line tension to a machine working on a slope, mechanising terrain that previously required manual falling.Winch-assist systems →
- Extracts stems by cable on steep terrain where ground-based machines cannot operate.
- Tracks fitted over paired wheels to spread load and improve traction. In wet or steep regions they determine whether the machine works at all, not merely how well.Tracks and tyres →
- The powered swivel between boom and attachment. Its mass subtracts directly from usable lift capacity, and rotator play is among the first things to check on a used grapple or head.
- The carrier's rated lifting capacity at each radius and height. Attachment, rotator and coupler weight all come off it before any timber is lifted.Hydraulics and carrier matching →
- A low-pressure return line taking internal leakage directly back to tank. Many high-flow attachments require one, and its absence will destroy a motor.
- The hydraulic flow a carrier can sustain at working pressure for a full shift — as opposed to peak flow, which it can reach briefly. Continuous-duty attachments such as mulchers need the first figure.
- Back-pressure in the return line. Excessive return pressure damages attachment motors and is routinely omitted from specification discussions.
- A mulching rotor design that controls engagement depth, lowering peak load, reducing rotor stalls and improving speed recovery and travel consistency.
- A durable mulching tool resisting impact and wear in difficult conditions, at higher cost and often a rougher finish than knife-type tools.
- Drives the stem through a harvester head. Roller configuration is species-specific — eucalyptus rollers differ substantially from softwood.
- Strips branches from the stem as it feeds through the head. A significant consumable, and heavily species-dependent.
- Records stem length as it feeds. Calibration drift here is a direct revenue leak against mill reconciliation.
- The high-speed circular cutting system used on most feller buncher heads. Tooth consumption is a primary operating cost.
- The pulling force a machine can develop at the ground — the figure that matters on grades, in soft soils and when extracting loaded.
- The rotational force available to swing the upper structure. It governs how quickly a machine can cycle between stems.
- The bunk area of a forwarder, measured in square metres. Load space rather than rated payload is frequently the binding constraint, particularly in hardwood.
- Machine weight distributed over its contact area. Determines rutting risk, wet-weather trafficability and compliance with harvest plan conditions.
- The track frame, chains, rollers, idlers and sprockets of a tracked machine, and a major cost driver over the machine's life.
- Engine hours recorded by the control module. On a used machine, compare these against idle hours — 10,000 hours with 4,000 idle is a very different wear profile from 10,000 under load.
- A measurement of internal pump leakage that exposes pumps approaching failure. The test most often skipped on used-machine inspections, and the one that finds the expensive problems.Used machine inspection →
- Combustion gas escaping past the piston rings into the crankcase — an indicator of engine wear.
- Laboratory testing of oil samples for wear metals and contamination, giving evidence of component condition that hours alone cannot.
- Harvesting all merchantable stems in a coupe in a single operation. The highest-production harvesting regime and the one most machine specifications are written around.
- Selective removal of some stems to concentrate growth on the remainder. Rewards manoeuvrability and restraint — the largest machine is usually the wrong answer.Pine thinning package →
- The trees left standing after thinning. Damage to them is a real cost that does not appear until the next rotation, which is why it is so often omitted from machine comparisons.
- The practice of establishing, tending and regenerating forest stands — including site preparation, planting, pruning and thinning.
- A defined harvesting area operating under a single harvest plan.
- The cleared area where stems are processed, sorted and loaded onto trucks in a full-tree system. Landing capacity frequently constrains the whole chain.
- The distance wood must travel from stump to roadside. The dominant variable in forwarder and skidder cycle time.
- The route along which stems are dragged to the landing. Trail quality and gradient drive skidder productivity and fuel burn.
- Branches, tops and non-merchantable residue left after harvesting. A feedstock for biomass, and an obstacle to site preparation.
- Forming raised planting positions to improve drainage and early seedling growth in plantation establishment.
- Disturbing the soil surface to expose mineral soil and improve planting or natural regeneration conditions.
- Removing bark during processing. Particularly important in eucalyptus plantation harvesting, where mills specify bark limits.
- One of eleven Australian government-designated concentrations of forest resource, processing, transport infrastructure and industry development. They shape where equipment demand, technicians and parts actually sit.Regional guide →
- Purchase price less residual value, plus finance, insurance, fuel, operator, service, repairs, tracks, attachments, consumables, transport, telematics, downtime and administration.Total cost of ownership →
- What the machine is expected to be worth at the end of the ownership period. It sets depreciation, and a narrow resale market makes it harder to predict.
- Hiring a machine or attachment without an operator. Commercially useful because it lets a contractor win the work, measure real productivity, and buy only once utilisation is proven.Buy vs hire →
- An arrangement where hire payments contribute to eventual purchase — suited to contractors who expect future work but need the asset to prove itself first.
- The contract to buy the product — chips, biomass or logs. In biomass it must precede the fleet decision, because it defines specification, moisture, contamination limits and delivery point.Biomass contractor package →
- The cost and time of getting equipment onto site. For machines moving frequently between small jobs it can exceed the productivity advantage of a larger machine.
- A weighted scoring method that deliberately prevents purchase price from dominating — reliability, local service and parts availability together carry 40%, against 3% for price.Decision framework →
- The high-velocity ejection of a broken saw chain fragment. A specific forestry hazard that operator protective structures are designed to address.
- Guarding and cab protection designed for forestry hazards — falling trees, branches, chain shot, timber penetration and rollover. A general civil excavator should not be assumed to have it.Operator protection →
- The state-level code governing mechanised felling, extraction, machinery, landings and transport. Tasmania and NSW both maintain current codes, and machine specification must comply with the one applicable to your state.
- Detection and suppression systems fitted to forestry machines, which operate in highly combustible environments with multiple ignition sources including exhaust, turbocharger, DPF, hydraulic oil and accumulated debris.