Shearex HM-100SV2 front-mount mulcher

A machine you cannot specify from a website

Every other head in the Shearex HM front-mount mulcher range can be narrowed down from published figures. The HM-100SV2 cannot, and that is the most important thing to understand before enquiring. Shearex describes its drive as a high-flow dual-motor system and does not publish a continuous flow range for it in the material available to us. There is no L/min figure on this page because there is none to quote, and any site that offers one has invented it.

What is published is enough to place the machine: 250 hp minimum carrier power, 254 cm of cutting width, a 60 cm optimal target material diameter and 2,311 kg of mass, more than double the entry HM-60. Below it, the HM-90SV is the 170 hp head with a 40 cm target that most heavy right-of-way contractors will actually run. This one belongs on high-horsepower purpose-built carriers doing industrial clearing, and it only makes sense when large timber is the year’s work rather than part of it.

Why the missing figure is the story

A single-motor head has one flow window and a compatibility question. A dual-motor head has a build: two motors whose displacement is chosen against the carrier’s circuit, and the resulting flow and pressure requirement belongs to that build rather than to the model. Two HM-100SV2 heads supplied to two different carriers are not necessarily asking for the same thing.

The practical consequence is that the entire specification conversation moves to the factory data sheet for the build being quoted. Ask for it in writing, before anything else, and expect it to state the flow and pressure requirement for both motor circuits, the recommended carrier configuration, and the case drain and return arrangement. Without that document there is nothing to check a carrier against, and a purchase at this level should not proceed on a brochure.

Once the sheet exists, the arithmetic is ordinary: flow multiplied by pressure, divided by 600, gives hydraulic power in kilowatts, as worked through on the VM-50SR page. As a purely illustrative sense of scale, a circuit supplying 400 L/min at an assumed 350 bar would be about 233 kW, roughly 313 hp of hydraulic power, which is the order of magnitude a 250 hp carrier is operating in once losses are counted. Neither number is published for this head; run the real ones through the hydraulic power calculator. See hydraulic matching for how to ask, and hydraulic cooling and heat, because a machine of this size working large timber in an Australian summer is a thermal problem before it is anything else.

254 cm, 60 cm and 2,311 kg

The 254 cm swath is the widest in the Shearex catalogue. The 60 cm published target diameter is a continuous production figure and it reaches mature eucalypt and pine, but the volume arithmetic that applies to every head in the range applies here with the most force: a 60 cm stem holds roughly nine times the wood of a 20 cm stem. A sparse stand of large trees is production work for this machine. A dense one can still be cheaper to fell and extract before mulching the residue, as maximum diameter versus production diameter explains and Australian hardwood reinforces for local species.

At 2,311 kg the head has to be assessed with the carrier manufacturer rather than against a capacity figure, particularly for stability on slopes and ground pressure on soft sites. The skid steer and track loader class page is included here only to make the point that this head sits entirely outside that class.

Where the work justifies it

The contracts are mining and pipeline corridors, large solar and wind farm site preparation and plantation thinning and re-establishment, where entire pushed-up rows and heavy leftover trunks are broken down on site across long campaigns. Rock, spoil and buried stumps are the norm on that ground, which is a carbide argument; blades remain the better choice only in clean green material. Blades versus carbide teeth sets out the trade.

A 2.5 metre head on a 250 hp tractor is a wide and heavy load to float, so transport permits and site access belong in the tender rather than in the mobilisation plan; transport and mobilisation covers what that involves.

Downtime is the real operating cost

Tooling at this scale is expensive and predictable. Downtime is expensive and not, which is why the parts conversation matters more here than on any other page in the family. A head this specialised is unlikely to have a twin sitting in the next state, and a carrier built around it has nothing else to do while it waits. Ask Machinery Specialist for Australian stock positions and honest lead times on the items that stop the machine, not just the items that wear out, and budget consumables per hectare across the campaign; wear parts to price before buying lists the set.

The sensible step down

On batters, drains and steep corridors the VM-65SV on a 25 to 40 tonne excavator will produce where this head cannot go at all; excavator mulcher versus skid steer mulcher covers the architectural trade. Within the front-mount range, step down to the HM-90SV if regular material is under 40 cm or the carrier sits between 170 and 250 hp, which describes most heavy clearing work in Australia. There is nothing to step up to, and for most buyers that is a reason to look down rather than a reason to look here.

What the factory data sheet has to tell you

Since the purchase rests on a document rather than on published figures, it is worth being specific about what that document needs to contain. Ask for it in writing, for the exact build being quoted, and expect it to state at minimum:

• The continuous flow and working pressure requirement for the dual-motor drive, given as a range with the pressure at which the flow applies.
• The motor displacement of each motor in the build, and the rotor speed that results at the stated flow.
• Maximum permissible return back-pressure, and the case drain requirement for each motor.
• The recommended carrier configuration, including cooling capacity and the circuit architecture the drive expects.
• The head’s mass and centre of gravity with the mounting arrangement quoted, for the carrier manufacturer to assess.

If any of those is missing, the gap moves onto the buyer. A dual-motor head fed by a circuit that was never checked against its stated requirement will run, and it will run at a rotor speed nobody specified, in timber that punishes exactly that.

The economics of a single-purpose machine

A 250 hp carrier with a 2,311 kg head on the front does one job. That is not a criticism, it is the whole proposition, and it means utilisation carries the entire commercial case. Finance, insurance, the operator, transport and the machine’s own depreciation accrue whether or not there is timber in front of it, so the rate has to be built on realistic annual hours rather than on the rate the machine achieves when it is working.

The businesses this suits are those with long campaigns and a visible pipeline: large corridor programmes, industrial site clearing and plantation rehabilitation measured in seasons rather than weeks. For anyone else, the honest comparison is hiring this capability when it is needed and owning something more flexible the rest of the time. Total cost of ownership and hire versus buy both apply with unusual force here, because there is no second use to fall back on when the pipeline thins.

Ground pressure, slopes and where a machine this size cannot work

Mass at the front of a carrier governs ground pressure and stability, and at 2,311 kg it governs them absolutely. On soft ground the combination rutts deeply, which on a rehabilitation or renewable site is rework somebody has to pay for. On side slopes the head sets the limit rather than the carrier’s own stability rating, and that limit belongs to the carrier manufacturer rather than to the operator’s judgement.

The result is that a machine capable of 60 cm timber is often excluded from parts of a site by the ground rather than the vegetation, which is why contracts of this scale usually run mixed fleets: this head on the traversable country, an excavator head on the slopes, drains and margins. Planning that split before mobilisation is far cheaper than discovering it with a bogged carrier.

Inspection, and a thin used market

A head this specialised turns over rarely, and the few that come to market are usually sold with the carrier, which makes inspection unusually important and comparison unusually hard. Establish which motor build is fitted and against which carrier it was specified, since a head matched to a different machine may not suit yours. Check both drive motors for case drain history and heat damage, examine the rotor for balance and for repaired holders, and look at the structure and mounting for cracking, because mass and vibration at this scale find weld repairs that a smaller head would tolerate. Inspecting used forestry attachments sets out the general method; the specific question here is always the build, not the model.

Confirm before ordering

• Factory data sheet for the quoted dual-motor build, stating flow and pressure for both circuits
• Carrier meets 250 hp and its high-flow circuit meets that stated requirement continuously at pressure
• Case drain and return arrangement specified against the data sheet, not adapted from another head
• Cooling capacity assessed for large timber in Australian summer conditions
• 2,311 kg assessed with the carrier manufacturer for stability and ground pressure
• Transport width, mass and permits for the carrier and head as a combination
• Australian stock and honest lead times on the parts that stop the machine, not only those that wear
• Delivered price including mounting plate, hoses, electrical harness and commissioning

Frequently asked questions