Inspecting Used Forestry Attachments

The second-hand market for forestry attachments is genuinely attractive. These are simple, heavily built machines with long lives, and a well-maintained head that has done a few thousand hours can be excellent value against a new one with a manufacturing lead time attached. The risk is not that used attachments are bad. It is that the two things which decide whether a particular unit is worth buying, its exact build specification and the condition of its structure, are the two things hardest to establish from photographs and a yard demonstration. This guide sets out how to confirm both, what to look at in each family, and what should and should not move the price.

Start with the serial number and the build, not the condition

The first question on any used attachment is not how worn it is. It is what it actually is. Attachments are sold with options that change weight, hydraulic requirement and capability substantially: rotation, accumulators, oscillation, tilt, grapples, heels, saw motor displacement, chain pitch, door control, blade or carbide tooling. A head described as a given model may be several different machines depending on what was ordered in the first place and what has been changed since.

The Trevi Benne WT Series is the clearest worked example, because it is the range most likely to appear second-hand in Australia and the one most often described loosely. The WT family covered six models, from the lightest units at around 340 kg through to the largest at around 1,835 kg, with published maximum diameters from 150 mm up to 500 mm and indicative flow requirements spanning roughly 50 to 180 L/min, and several models were offered with additional rotation configuration that changes the working weight. The family has since been superseded by the current WL and WR ranges. A listing that says only “Trevi Benne WT tree shear, six-size range” tells you almost nothing. The serial number, matched to the factory build record, tells you the model, the original diameter rating, the flow requirement, whether rotation was fitted and which bracket it left the factory with.

Ask the seller for photographs of the data plate and the serial, and take those to the Australian distributor rather than relying on the seller’s description. The three answers that matter commercially are whether the original carrier pairing was appropriate for the work the unit has done, what the current hydraulic requirement is for that build, and whether blades, pins and bushes for that serial are still available and at what price. A legacy attachment with no parts pathway is a short-term asset regardless of how good it looks.

Structural red flags that apply to every family

Structure is where a used attachment is either sound or a liability, and the same signs recur across the families. Look for cracking or repair around the mounting bracket and headstock, since that is where the highest loads concentrate and where a previous owner’s side-loading shows up first. Look for twisting or misalignment between jaws, blades or tines, which is evidence the attachment has been used as a lever rather than a cutter. Check that pin bores are round rather than ovalled, and that pins and bushes are not simply worn but worn evenly, because uneven wear indicates a frame that is no longer square.

Cylinder rods should be clean, unpitted and unscored, with no weeping at the gland. Hoses should be routed and protected rather than patched, and a head full of temporary repairs is a good indication of how it has been maintained generally. Rotators deserve their own attention: check for play, for leakage and for how the hoses pass through the swivel, because a rotator is a slow and expensive thing to rebuild and a failure stops the whole attachment.

What to inspect, family by family

On a tree shear, inspect blade straightness, the blade edge and any previous hard-facing, the main pivot pins and bush wear, the cylinder rods and seals, frame cracking, rotator play and leakage, hoses, bracket welds and the accumulator arms if fitted. Pay particular attention to repairs around the blade carrier, which is the highest-stress area on the head.

On a Trevi Benne WE root and stump cutter, check jaw alignment and cutting edges, pin bores, bushes, cylinder rod and barrel, the mounting frame and any weld repairs, hose routing and the coupler bracket. Signs of twisting or heavy side loading matter more here than anywhere else, because extraction work applies leverage the attachment was never intended to carry.

On a Dipperfox stump grinder, inspect centre screw wear and blade condition, listen for gearbox noise and look for gearbox leakage, check the hydraulic motor and hoses, the mounting frame and bracket, and look for evidence of shock loading or repaired structure. Ask for operating video and service records, since gearbox history is not visible from outside.

On a forestry mulcher, check rotor straightness and run it at full speed to assess vibration, then check rotor bearing play, missing tools, cracked or torn holders, wear liners, skid shoes, the drive belt, hydraulic motor leakage, and the door, grapple and tilt pivots if fitted. Vibration is the single most informative test on a mulcher, because an out-of-balance rotor destroys bearings and a repaired rotor rarely balances as it did when new.

On a grapple saw, inspect grapple pins and tine wear, rotator play and leakage, the saw box, the saw motor, the bar mount, the automatic tensioning system, the chain lubrication system, hose routing through the rotator, frame cracking, the adaptor and the cab controls. Confirm which mounting architecture the unit actually is, since rigid, tiltrotator and tree-care configurations differ in weight and capability and are easily conflated.

On a forestry grapple, check tine wear and tine bending, jaw alignment, main pins and bush wear, cylinder rods, rotator leakage and bearing play, the hose swivel, frame cracking and the attachment bracket. Load real timber and watch how the jaws meet under pressure rather than closing them empty.

On mechanical pruning equipment, inspect blades and discs, bar straightness, pins, the cutting cylinder, the motor, the valve block, rotation, the bracket, hose condition and any cracking from impact. Long bars are particularly sensitive to bending, and a bent bar is often uneconomic to repair.

On compactors and auger drives, check the vibration system, the isolation buffers, the base plate, the hydraulic motor and frame cracking on a compactor, and teeth, pilot, flight condition, gearbox oil, output shaft and bracket pins on an auger drive. Collapsed isolation buffers are both a wear item and a sign the unit has been run hard past its service point.

Insist on a live test under load

The most important part of the inspection is the part sellers are least keen on. An attachment that opens and closes in a yard has demonstrated that the cylinder strokes. What you need to see is the attachment doing its actual job, in material comparable to yours, on a carrier with documented hydraulics.

1. Confirm serial and build
2. Fit to a documented carrier
3. Work under loadin real material
4. Run to temperature
5. Inspect again, hot

For a shear, that means cutting stems across your normal diameter range and watching whether the stroke stays decisive through the last third of the cut. For a root cutter, splitting an actual stump or heavy timber section. For a mulcher, running at full rotor speed under load long enough to assess vibration, bogging and oil temperature. For a grapple saw, running the saw through a cut and then checking chain tension, lubrication delivery and the rotator under a suspended load. For a grapple, closing on real timber. For a stump grinder, drilling a representative stump and listening to the gearbox under changing resistance.

Then inspect again while everything is hot, because seals that look dry cold will often weep at working temperature, and that is precisely the condition in which the attachment will spend its life. The material should reflect your work, which in most of Australia means hardwood; the reasons are covered in Australian hardwood and attachment performance.

Weld repairs, records and what they mean

Welding on a used forestry attachment is not automatically disqualifying. These machines work hard and competent repairs are normal. What matters is whether the repair was engineered and documented, or improvised.

Ask for repair records, photographs of the repair in progress, and the name of whoever carried out the work. A repair to a wear surface, a liner, a skid shoe or a tine tip carried out to the manufacturer’s procedure is routine. A repair to a main structural member, a pin boss, a headstock or a rotor with no records is a different matter, because you cannot tell from the outside whether the underlying member was cracked, how far the crack ran, or whether the repair introduced its own stress. Extensive undocumented structural welding is the clearest reason to walk away from an otherwise attractive unit.

What devalues a unit, and what does not

Buyers frequently price the wrong things. Paint, surface rust, scratched decals, worn hoses and consumed cutting tools are cheap and expected, and a seller who has left the teeth or blades worn out has simply left you the bill for the next set. Price those items and subtract them, but do not treat them as evidence of a bad machine.

The genuine value destroyers are structural: an ovalled pin bore, a twisted frame, undocumented repairs to load-bearing members, a rotor that will not balance, a rotator with play, a gearbox with unexplained noise, and a build specification that does not suit your carrier. Add to that list the commercial factors, which are a serial with no parts pathway, missing options that you would then have to buy, and a bracket that does not match your hitch. A useful way to settle on a number is to work backwards from the new price.

Set against that, some things add real value and are worth paying for: a documented service history, original brackets and hoses, a known single owner, an attachment that has been stored on a stand under cover, and a serial that the Australian distributor can still support with blades, pins, bushes and seal kits. Those are the units that hold their price when you come to sell, which matters more than most buyers expect; see total cost of ownership for how residual value moves the hourly cost, and hire versus buy for when a used purchase beats both.

Confirm before buying

• Serial number, data plate photographs and the factory build specification for that serial
• Current hydraulic requirement for that exact build, and whether your carrier meets it under load
• Attachment weight in its actual configuration, including bracket and rotator, checked against your lift chart
• Bracket and hitch compatibility, and the cost of changing it if not
• Parts availability for that serial: blades or teeth, pins, bushes, seal kits, rotator and gearbox components
• Written repair history, including any structural welding, with photographs and the repairer's name
• Service records for gearboxes, rotators and saw motors
• A live test under load in material comparable to your work, on a carrier with documented hydraulics
• A second inspection at working temperature, looking specifically for weeping seals
• A written list of the wear parts and repairs needed immediately, priced, before you agree a number

Frequently asked questions