Forestry Attachments for 16 to 25 Tonne Excavators

What this class is commercially good at

The 20 tonne excavator is the most common heavy machine in Australian civil fleets, and the 16 to 25 tonne band is where every attachment family on this site has a model published for it. A WR15 shear, a WE10 or WE15 stump cutter, an SC850 Pro, a VM-50SR or VM-60SR mulcher, an EX36 grapple saw and an EX36 or EX40 grapple all sit inside the band, which means one carrier can be specified for the entire clearing chain from standing tree to compacted backfill.

The commercial sweet spot is production clearing where the carrier is already on the project for earthworks: subdivision and solar farm clearing, transmission and pipeline corridors, road widening, plantation conversion and biomass harvesting. The subdivision, solar and wind farm, mining and pipeline and biomass and chipper applications are built around this class because the timber is large enough that holding and placing it, not just cutting it, is where the money is made or lost.

What it is bad at

Two things. The first is mobilisation: a 20 tonne machine is a float move with permits and pilots to think about, so a contract with a dozen small scattered sites often suits the 10 to 16 tonne class better even though the bigger machine would be faster on each of them. The second is utilisation: at this size the attachment economics compete with dedicated machines. A contractor mulching 2,000 hours a year should compare a purpose-built carrier, and a contractor felling plantation timber for thousands of hours should compare a feller buncher, as the tree shear versus feller buncher comparison sets out. The excavator wins when clearing is one stage of a project, not the whole business.

Attachment families that make sense

Felling centres on the Trevi Benne WR15, indicatively matched to 17 to 22 tonne carriers with a nominal 500 mm cutting class, twin Hardox blades, hydraulic rotation options, an optional accumulator and an optional fork tower for handling larger stems. The WR10 covers the 16 tonne end and the WR20 enters at 23 tonnes with a nominal 550 mm class. For stumps the Dipperfox SC850 Pro (13 to 30 tonnes, 580 kg, 850 mm, 43,000 Nm) grinds in place, while the Trevi Benne WE15 (20 to 28 tonnes, 2,240 kg, 1,400 mm jaw) and the WE10 to 18 tonnes extract and split the root ball for civil work or biomass.

Mulching is a hydraulics conversation in this class. The Shearex VM-50SR for 15 to 20 tonne carriers weighs 975 kg, cuts 123 cm with a 25 cm optimal target diameter and needs 159 to 238 L/min continuous with an 80 hp minimum carrier. The VM-60SR for 20 to 25 tonne carriers weighs 1,188 kg, cuts 149 cm with a 40 cm target diameter and needs the same 159 to 238 L/min but a 130 hp minimum carrier, which many 20 tonne machines do not have to spare.

Handling and controlled cutting scale with the timber. The Powerhand EX36 forestry grapple (16 to 25 tonnes, 837 kg with rotator, 0.36 m², 1,928 mm opening) and the EX36 grapple saw (1,176 kg, 1,000 mm bar, 650 mm cut) are the heavy brash and large-stem tools, the EX28 pair spans the whole class at lower mass, and the EX40 grapple enters at 20 tonnes with 1,091 kg and a 2,137 mm opening for high-volume chipper feeding. The Terragrip (around 14 to 25 tonnes) rips, rakes and grabs in the clean-up phase, the OMEF CS400H prunes 420 mm limbs to 24 tonnes, and the CPT910 compactor runs to 20 tonnes.

Attachment families that do not make sense

The VM-65SV mulcher is published from 25 tonnes with a 170 hp minimum carrier, so it belongs to the 25 to 40 tonne class even though a 25 tonne machine touches its band. Everything published for mini and mid-class carriers, from the SC400 and SC600 to the CS100 to CS300 pruners, the TRI and BTD bars, the VM-25SK and VM-35SK and the CPT180 and CPT425, will bolt on but wastes the carrier and often the reach; the SC600 stops at 12 tonnes and the VM-40SL at 15. A used WT Series shear at the WT015 or WT020 size may be offered for this class and deserves a serial-specific assessment.

Stability, lift chart and hydraulic realities

Assume, purely for illustration, that a 21 tonne machine is rated at 3,500 kg over the side at the radius it fells at. A WR15 somewhere in the family’s 1,250 to 2,225 kg span, say 1,800 kg with rotation, plus a 150 kg hitch leaves about 1,550 kg for the tree. A 500 mm green eucalypt of any real height can exceed that, which is why the nominal 500 mm class describes what the blades will sever, not what the machine will carry to the windrow. The WE15 is the extreme case: 2,240 kg of attachment before a soil-laden root ball is added, on a machine indicatively matched from 20 tonnes. The lift chart guide and lift capacity calculator do the arithmetic; the heavy counterweight and the long or standard boom choice change the answer and belong in the quotation. Operators should establish exclusion zones and follow applicable WHS procedures and manufacturer instructions, and no saw or shear capacity is a safe suspended-load figure.

Flow demand in this class runs from roughly 100 to 240 L/min, with the VM-50SR and VM-60SR at 159 to 238 continuous, the SC850 Pro at 110 to 230 and the EX saws depending on the saw motor displacement chosen to suit the carrier. The hydraulic power calculator is worth running: 238 L/min at 350 bar is roughly 139 kW of theoretical hydraulic power, which is a large share of what a 20 tonne engine produces, so the question becomes what the carrier can sustain under load, not what the pump can peak at. Case drain, electrical door control and second double-acting circuits for tilt or grapple options are normal here, and cooling is the buying issue that most often surfaces after delivery on a 20 tonne machine bought for earthworks. See cooling and heat and hydraulic matching.

Transport and mobilisation

This class is a float class. In general terms a 20 tonne excavator travels on a low loader with the permit, pilot and route considerations that apply to that combination, and every attachment adds mass and, on stands, deck length. A WE15 at 2,240 kg and a VM-60SR at 1,188 kg are not incidental to the load, and the choice between carrying attachments on the float or on a separate truck is a cost decision to make before tendering. Mobilisation is also why this class suits long project stages rather than scattered short jobs. The transport and mobilisation guide covers the planning.

Fleet-building logic

The economics rest on the carrier already being financed for earthworks and on the clearing stage otherwise going to a subcontractor. A 21 tonne machine with a bucket, a WR15, an SC850 Pro, an EX36 grapple and a CPT910 can fell a subdivision, stack for the chipper, drill the stumps, load the biomass and compact the trenches, then move to bulk earthworks on the same site. As an illustration only, assume the carrier costs $220 per hour to own and run. If the attachments keep it earning 500 paid hours a year at an assumed $340 charge-out, that is $170,000 of revenue against $110,000 of running cost, or about $60,000 of contribution, plus the margin on subcontract clearing that stays in the business. A full set of heads for this class is a six-figure decision, so that contribution has to be repeatable rather than a one-project number. The comparison that matters is “20 tonne excavator plus attachments” against “dedicated felling machine plus the existing excavator”, and the total cost of ownership and hire versus buy guides set that out.

Step up or step down

Step up to the 25 to 40 tonne class when 550 mm hardwood is routine, when the VM-65SV target diameter and cutting width are needed for industrial corridors, or when the EX40 saw in tiltrotator configuration is the right tool for dangerous-tree dismantling at scale. Step down to the 10 to 16 tonne class when the float bill outweighs the production gain on scattered sites, or when the timber rarely exceeds 400 mm. Stay in class when the contract is a full clearing chain on a large site and the carrier will go straight into earthworks afterwards; that is the job this class was bought for.

Confirm before ordering

• Over-side lift at the real felling or extraction radius against the attachment, rotator, fork tower and hitch, with the counterweight and boom option stated.
• Continuous auxiliary flow and pressure under load for the exact carrier, and the minimum carrier power the mulcher data sheet specifies.
• Case drain, second double-acting circuit and electrical control requirements for door, tilt and grapple options.
• Cooler capacity and acceptable oil temperature for continuous mulching in summer, and any additional cooling the distributor recommends.
• Float, permit and route requirements with every attachment and stand loaded, or the cost of a separate attachment truck.
• Blade, cutting edge, centre screw, chain, bar and tooth pricing and Australian availability for each model quoted.
• A demonstration in Australian hardwood of the diameter class the contract actually contains.

Frequently asked questions